Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Election/Restrictions
Claims 13-17 withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected species D, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 05/28/2026.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1-2, 4-7, 9-12 are rejected under 35 U.S.C. 103 as being unpatentable over Kobayashi (US 20170190020 A1) in view of Qian (US 20140273749 A1) and Fujita (US 20080071414 A1).
Kobayashi discloses:
Regarding Claim 1, Kobayashi discloses A polishing method comprising:
polishing a substrate by pressing the substrate with a polishing head against a polishing surface of a polishing pad while rotating a polishing table supporting the polishing pad (See Para [0039] “Polishing of the wafer W is performed as follows. The polishing head 5 and the polishing head 3 are rotated individually in directions indicated by arrows, and the polishing-liquid supply nozzle 10 supplies the polishing liquid (or slurry) onto the polishing pad 1. While the polishing liquid is being supplied, the polishing head 5 presses the wafer W against the polishing surface 1a of the polishing pad 1.”);
producing a spectrum waveform while polishing the substrate (Kobayashi discusses 3 types of spectrums used in calculation, a measurement spectrum, taken before the wafer is polished (See Para [0056]), a sampling spectrum, taken while the wafer is being polished (See Para [0069]), and a reference spectrum, used for comparison (see Para [0059] cited below)
Para [0056] “As a result, the spectrum, produced from the reflected light from the wafer, varies according to the thickness of the upper film. The spectrometer 44 breaks up the reflected light according to the wavelength and measures the intensity of the reflected light at each of the wavelengths. The processor 32 produces the spectrum from the intensity data of the reflected light (i.e., the optical signal) obtained from the spectrometer 44. Hereinafter, a spectrum produced from the reflected light from the wafer W to be polished will be referred to as measurement spectrum. This measurement spectrum is expressed as a line graph (i.e., a spectral waveform) indicating a relationship between the wavelength and the intensity of the light. The intensity of the light can also be expressed as a relative value, such as a reflectance or a relative reflectance.”
Para [0069] “While the target wafer is being polished, the target wafer is irradiated with the light as described above. The processor 32 produces a spectrum from the reflected light from the target wafer, and selects a spectrum group containing a reference spectrum which is closest in shape to the produced spectrum. This spectrum used to select a spectrum group will hereinafter be referred to as sampling spectrum. As with the measurement spectrum, the sampling spectrum is a spectrum produced from the light reflected from the wafer W to be polished. The comparison in shape between the sampling spectrum and the reference spectrum is performed on the basis of a deviation of the reference spectrum from the sampling spectrum. More specifically, the processor 32 calculates the deviation between these two spectra with use of the following equation.”); and
selecting one reference spectrum waveform from a plurality of reference spectrum waveforms accumulated before the polishing of the substrate (See Para [0059] “The processor 32 is configured to determine the film thickness from a comparison between the measurement spectrum and a plurality of reference spectra. The optical film-thickness measuring device 25 is coupled to a storage device 58 show in FIG. 1 and FIG. 3. The plurality of reference spectra are stored in this storage device 58. FIG. 7 is a diagram illustrating a process of determining the film thickness from the comparison between the measurement spectrum and the plurality of reference spectra. The processor 32 compares the spectrum, which is produced when the wafer is being polished, with the plurality of reference spectra so as to determine a reference spectrum which is closest in shape to the measurement spectrum, and obtains a film thickness which has been associated with the determined reference spectrum. The reference spectrum which is closest in shape to the measurement spectrum is a spectrum with the smallest difference in the relative reflectance between the reference spectrum and the measurement spectrum.”),
and suggests but does not explicitly disclose polishing the substrate includes an asperity polishing process of polishing the substrate before a film thickness of the substrate reaches an asperity-eliminated film-thickness, and a flat polishing process performed after the asperity polishing process (Kobayashi discusses in Para [0080] and [0081] (cited below) discusses two halves of the polishing process, one of which being before asperities are removed (the asperity polishing process) and one after (the flat polishing process),
Para [0080] “As the polishing of the target wafer progresses, the measurement spectrum may vary greatly due to some factors, such as a temperature of the target wafer, a change in the shape of the surface of the target wafer, etc. For example, in an initial stage of the polishing process of the target wafer, asperities (or steps) may exist on the surface of the target wafer. When such asperities are removed by the polishing, the measurement spectrum may vary greatly. In a stage where the asperities remain unremoved, the measurement spectrum is relatively unstable depending on the state of the asperities, and may vary between wafers or between areas within the surface of the wafer. In contrast, in a stage where the asperities have been removed by the polishing, a stable measurement spectrum is likely to be obtained.”
Para [0081] “Thus, the processor 32 may produce a sampling spectrum again during the polishing process of the target wafer, and may select again a spectrum group containing a reference spectrum which is closest in shape to this sampling spectrum produced. Since the sampling spectrum produced during the polishing process of the target wafer is substantially the same as the measurement spectrum, the measurement spectrum may be used as the sampling spectrum. After the spectrum group has been selected again, the processor 32 selects a reference spectrum, which is closest in shape to the measurement spectrum, from the spectrum group that has been selected again. By thus selecting the spectrum group again, a more accurate film thickness can be obtained especially in a latter half of the polishing process which has an important significance for a finishing performance.”).
the asperity polishing process includes:
determining a plurality of film thicknesses at a plurality of measurement points on the substrate based on a film thickness of reference film data calculated based on a first relational expression (See Para [0088] “In step 4, the processor 32 selects the smallest one of the deviations determined in the step 3 (i.e., the smallest deviation) with respect to each of the measurement points on the target wafer, selects a spectrum group to which a reference spectrum, corresponding to the selected smallest deviation, belongs, and estimates the film thickness of the target wafer from the film thicknesses measured before and after the processing process and the polishing time of the selected spectrum group, and from the polishing time (i.e., the time that has elapsed from the polishing start) of the reference spectrum with the smallest deviation.”); and
comparing the spectrum waveform with the selected reference spectrum waveform to determine whether the asperity polishing process should be terminated (See Para [0079] “Once a spectrum group has been selected, the processor 32 produces the measurement spectrum during polishing of the target wafer, and selects a reference spectrum, which is closest in shape to the produced measurement spectrum, from the spectrum group that has been selected as discussed above. More specifically, the processor 32 uses the equation (2) to determine a reference spectrum that is closest in shape to the measurement spectrum, i.e., a reference spectrum with the smallest deviation from the measurement spectrum, and obtains a film thickness that has been associated with the determined reference spectrum. The processor 32 monitors the polishing process of the target wafer based on the determined film thickness, and determines a polishing endpoint at which the film thickness is lower than a predetermined target value. The processor 32 sends a polishing endpoint detection signal to the polishing controller 12, which in turn terminates polishing of the target wafer in response to the polishing endpoint detection signal.”), and
the flat polishing process includes determining a plurality of film thicknesses at a plurality of measurement points on the substrate based on a film thickness of reference film data calculated based on a second relational expression (Para [0081] cited above discusses repeating the process cited during Para [0079] while using the measurement spectrum as the sampling spectrum, resulting in a second relational expression).
But does not disclose:
Wherein the waveform is a torque waveform
wherein producing the torque waveform comprises producing a torque waveform from a measurement value of a torque for rotating the polishing table, a measurement value of a torque for rotating the polishing head about an axis thereof, or a measurement value of a torque for oscillating the polishing head along the polishing surface,
Wherein the asperity polishing process and flat polishing process are distinct separate process.
However, it would be obvious to one of ordinary skill in the art before the effective filling date of the invention to separate the asperity and flat polishing processes into two separate process, as Para [0081] discusses performing the same process but with a different reference spectrum (the measurement spectrum) for the second half of the polishing, as such it would be obvious to terminate the first half which uses the first relational expression at an end point, then initiate the second half, using the second relational expression, as Kobayashi in Para [0081] discusses that doing this would provide more accurate film thickness measurements which would have important significance for finishing performance.
Additionally, Qian discusses a similar polishing process including determining a bulk endpoint time, and discusses that different aspects of the polishing process can be monitored in order to determine an end point (See Para [0123] “In certain implementations, the expected bulk endpoint time is predetermined or calculated as a combination of expected endpoint times of multiple zones. In certain implementations, the bulk endpoint time may be detected using at least one of a motor torque monitoring system, an eddy current monitoring system, a friction monitoring system, or a monochromatic optical system as previously described herein.”) including an optical monitoring system and a motor torque monitoring system.
And Fujita discloses a similar polishing process including
wherein producing the torque waveform comprises producing a torque waveform from a measurement value of a torque for rotating the polishing table, a measurement value of a torque for rotating the polishing head about an axis thereof (See Para [0064]- [0065] discussing the torque measurement unit and subsequent units for producing and analyzing torque waveforms), or a measurement value of a torque for oscillating the polishing head along the polishing surface,
determining a polishing endpoint by producing a Torque waveform (See Para [0073] “Next, "detection of the polishing end point according to the torque waveform from which the periodic noise components are removed" will be explained with reference to FIG. 4(a) to 4(c).”) Wherein the Torque waveform of a substrate to be polished (Tb2) is compared to a Torque waveform (Tb1) where the endpoint of Tb1 is presumed to be correct (First See Para [0075] describing the parameters of each torque wave form, with Tb1 having a correct end point E and Tb2 having an erroneous endpoint G, Then See Para [0076]-[0079] describing how both wave forms are differentiated twice, and the changing points Q1 and Q2 are detected to determine the appropriate endpoint time). It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the polishing method of Kobayashi to monitor and analyze torque waveforms instead of the optical spectrum waveforms, as both the monitoring and comparison of both spectrum and torque waveforms for end point detection are known in the art and one of ordinary skill in the art would have found it obvious to substitute optical spectrum analysis for a torque waveform analysis. See MPEP 2143 I B.
Regarding Claim 2, Kobayashi as modified discloses all the limitations of claim 1 and in addition discloses, Wherein selecting one reference torque waveform from the plurality of reference torque waveforms accumulated before the polishing of the substrate comprises selecting one reference torque waveform from the plurality of reference torque waveforms based on a film-thickness profile of the substrate before polishing (See Para [0078]] “Alternatively, if spectrum groups have been determined using the standalone film-thickness measuring unit or the inline film-thickness measuring unit, it is possible to measure the structure and/or the thickness of the underlying layer of the target wafer with use of the inline film-thickness measuring unit assembled in the polishing apparatus and to select a corresponding spectrum group.”) but does not explicitly disclose selection based off a type of the substrate.
However, Kobayashi does disclose selecting a reference spectrum from a group of reference spectrum by having a process determine which reference spectrum is closest in shape to the measurement spectrum (measurement spectrum of the target wafer, See Para [0059] “The processor 32 compares the spectrum, which is produced when the wafer is being polished, with the plurality of reference spectra so as to determine a reference spectrum which is closest in shape to the measurement spectrum, and obtains a film thickness which has been associated with the determined reference spectrum. The reference spectrum which is closest in shape to the measurement spectrum is a spectrum with the smallest difference in the relative reflectance between the reference spectrum and the measurement spectrum.”). Additionally, Kobayashi discloses only one “type” of substrate.
Fujita discloses that the output of the torque waveform changes drastically when the type of polishing layer on the wafer undergoes a change (First see Para [0084]- [0087] discussing a set-up wherein the conductive film to be polished and the film of a material that is different from the conductive film to be polished are laminated on the wafer. Then See Figs. 5 and 6 and Para [0088] and [0089] discussing the large jump in the torque value at point A where the material forming the layer being polished changes).
It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the spectrum selection process of Kobayashi as modified to ensure that the reference waveform is of a wafer of the same type of the target wafer, as Kobayashi emphasizes selecting a reference spectrum to that is most similar to the target one, and Fujita discloses that wafers comprising different types of materials would give different torque waveforms, and one of ordinary skill in the art before the effective filling date of the invention would find it obvious that selecting a similar reference waveform would involve selecting a reference waveform from a wafer of the same type as Kobayashi in Para [0011] discloses “It is an object of the present invention to provide a polishing method and a polishing apparatus which are capable of measuring an accurate film thickness while eliminating an influence of structural variation of an underlying layer.”.
Regarding Claim 4, Kobayashi as modified discloses all the limitations of claim 1 and in addition suggests, but does not explicitly disclose wherein determining whether the asperity polishing process should be terminated includes:
after a predetermined period of time has elapsed, comparing a shape of the torque waveform with a shape of the selected reference torque waveform till a polishing time corresponding to a present polishing time, and calculating a degree of coincidence of the shape of the torque waveform and the shape of the selected reference torque waveform (See Para [0092] of Kobayashi (cited below) discussing: wherein after a number of revolutions of the polishing pad passes a predetermined amount (which would be a function of time and speed of the polishing pad), the waveforms for each measurement point on the wafer are compared to the reference waveforms and the deviations are calculated (analogous to calculating a degree of coincidence of the waveform),
[0092] “If the present number of revolutions of the polishing table 3 is larger than the predetermined number of revolutions NM, the measurement spectrum obtained in each of the measurement points on the target wafer is compared with the reference spectra which belong to the optimum spectrum group determined in the step 6, and spectrum deviations are calculated (step 7). A range of the revolutions in which the reference spectra are to be compared is not the revolutions NR in the initial stage of the polishing process, but should be determined in view of the change in the film thickness which occurs as polishing of the wafer progresses, and may be a total revolution range (i.e., a total film-thickness range).”);
comparing the calculated degree of coincidence with a predetermined reference degree of coincidence, and when the calculated degree of coincidence is more than or equal to the predetermined reference degree of coincidence, calculating a difference between a polishing time at an asperity-eliminated point estimated from the selected reference torque waveform and the present polishing time (Kobayashi in para [0093] discusses determining a polishing time based on the reference spectrum with the smallest spectrum deviation at a measurement point, and then determining if polishing should be stopped on the basis of if the total polishing time has reached the reference polishing time
[0093] “In step 8, the processor 32 determines a polishing time (i.e., a time that has elapsed from the polishing start) allocated to a reference spectrum with the smallest spectrum deviation calculated in step 7 at each of the measurement points on the target wafer, and calculates a film thickness. In step 9, the processor 32 determines whether the polishing process is to be terminated on the basis of a designated polishing time or a polishing endpoint detection or other criterion. If the polishing process is not to be terminated, then the step 1 is carried out again.”); and
determining that the asperity polishing process should be terminated when polishing time of the substrate has reached a time that is calculated by adding the present polishing time to the difference (as previously discussed above, the polishing time is determined then the processor determines when to end the polishing based on the determined polishing time, further see Para [0079] “More specifically, the processor 32 uses the equation (2) to determine a reference spectrum that is closest in shape to the measurement spectrum, i.e., a reference spectrum with the smallest deviation from the measurement spectrum, and obtains a film thickness that has been associated with the determined reference spectrum. The processor 32 monitors the polishing process of the target wafer based on the determined film thickness, and determines a polishing endpoint at which the film thickness is lower than a predetermined target value. The processor 32 sends a polishing endpoint detection signal to the polishing controller 12, which in turn terminates polishing of the target wafer in response to the polishing endpoint detection signal.”) or a value obtained by multiplying the difference by a coefficient.
It would have been obvious to one of ordinary skill in the art before the effective filling date of the invention to modify determination of when asperity polishing process is terminated (See rejection of claim 1) to include after a predetermined period of time has elapsed, comparing a shape of the torque waveform with a shape of the selected reference torque waveform till a polishing time corresponding to a present polishing time, and calculating a degree of coincidence of the shape of the torque waveform and the shape of the selected reference torque waveform;
comparing the calculated degree of coincidence with a predetermined reference degree of coincidence, and when the calculated degree of coincidence is more than or equal to the predetermined reference degree of coincidence, calculating a difference between a polishing time at an asperity-eliminated point estimated from the selected reference torque waveform and the present polishing time; and
determining that the asperity polishing process should be terminated when polishing time of the substrate has reached a time that is calculated by adding the present polishing time to the difference or a value obtained by multiplying the difference by a coefficient.
As applying the principles of end point determination to the asperity polishing process would allow for a more accurate determination of when the flat polishing process would be started, which would result in improved accuracy regarding film thickness and improve finishing performance as indicated by Kobayashi Para [0081] previously cited.
Regarding Claim 5, Kobayashi as modified discloses all the limitations of claim 1 and in addition discloses further comprising: after a predetermined period of time has elapsed, comparing a shape of the torque waveform with a shape of the selected reference torque waveform till a polishing time corresponding to a present polishing time, and calculating a degree of coincidence of the shape of the torque waveform and the shape of the selected reference torque waveform (See Para [0092] of Kobayashi (cited below) discussing: wherein after a number of revolutions of the polishing pad passes a predetermined amount (which would be a function of time and speed of the polishing pad), the waveforms for each measurement point on the wafer are compared to the reference waveforms and the deviations are calculated (analogous to calculating a degree of coincidence of the waveform),
[0092] “If the present number of revolutions of the polishing table 3 is larger than the predetermined number of revolutions NM, the measurement spectrum obtained in each of the measurement points on the target wafer is compared with the reference spectra which belong to the optimum spectrum group determined in the step 6, and spectrum deviations are calculated (step 7). A range of the revolutions in which the reference spectra are to be compared is not the revolutions NR in the initial stage of the polishing process, but should be determined in view of the change in the film thickness which occurs as polishing of the wafer progresses, and may be a total revolution range (i.e., a total film-thickness range).”);
and suggests but does not explicitly disclose
comparing the calculated degree of coincidence with a predetermined reference degree of coincidence, and when the calculated degree of coincidence is less than or equal to the predetermined reference degree of coincidence, changing a polishing condition (See Para [0079] “The processor 32 monitors the polishing process of the target wafer based on the determined film thickness, and determines a polishing endpoint at which the film thickness is lower than a predetermined target value. The processor 32 sends a polishing endpoint detection signal to the polishing controller 12, which in turn terminates polishing of the target wafer in response to the polishing endpoint detection signal. At each point in time during the polishing process of the target wafer, the processor 32 determines manipulated variables (or control variables) for obtaining a predetermined distribution of remaining film thicknesses, on the basis of the film thicknesses determined in the respective areas on the surface of the target wafer. The manipulated variables (or control variables) may be pressure command values for the pressure chambers D1 through D5. The processor 32 sends these pressure command values to the polishing controller 12, which updates the pressures based on the command values that have been sent to the polishing controller 12.”).
It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify process of Kobayashi as modified to manipulate the polishing conditions in reaction to the degree of coincidence with respect to a predetermined degree of coincidence as suggested by Kobayashi as doing so would allow for correction of the polishing process in order to increase the closeness or degree of coincidence between the target wafer waveform and the reference waveform, increasing the accuracy of the polishing process.
Regarding Claim 6, Kobayashi discloses
A polishing apparatus comprising:
a polishing table (3) configured to support a polishing pad (1);
a table motor (19) configured to rotate the polishing table (See Para [0038] “The polishing table 3 is coupled to a table motor 19 through a table shaft 3a. The table motor 19 is disposed below the polishing table 3, and is configured to rotate the polishing table 3 in a direction indicated by arrow.”);
a polishing head (5) having a plurality of pressure chambers (d1, d2, d3, d4) configured to press a substrate against a polishing surface of the polishing pad (See Para [0040] “The polishing head 5 includes a carrier 6 in the form of a circular plate, a circular flexible elastic membrane 7 which defines a plurality of pressure chambers D1, D2, D3, D4 beneath the carrier 6, and a retainer ring 8 for pressing the polishing pad 1.”);
a film-thickness sensor (31) configured to output a film-thickness signal that varies according to a film thickness of the substrate (See Para [0046] “This optical film-thickness measuring device 25 has a film thickness sensor 31 for obtaining an optical signal that varies in accordance with the film thickness of the wafer W, and a processor 32 for determining the film thickness from the optical signal.”);
a plurality of pressure regulators coupled to the plurality of pressure chambers (See Para [0042] “The pressure chambers D1, D2, D3, D4 are coupled to fluid lines G1, G2, G3, G4, respectively, so that pressurized fluid (e.g., pressurized gas, such as pressurized air) having regulated pressure(s) is supplied through the fluid lines G1, G2, G3, G4 into the pressure chambers D1, D2, D3, D4. Vacuum lines U1, U2, U3, U4 are coupled to the fluid lines G1, G2, G3, G4, respectively, so that negative pressures can be created in the pressure chambers D1, D2, D3, D4 by the vacuum lines U1, U2, U3, U4. The internal pressures in the pressure chambers D1, D2, D3, D4 can be varied independently of each other for thereby independently regulating polishing pressures on corresponding four areas of the wafer W, i.e., a central area, an inner intermediate area, an outer intermediate area, and a peripheral area.”), respectively;
an operation controller configured to control the polishing apparatus,
wherein the operation controller is configured to produce a waveform from a measurement value of the wafer (Kobayashi discusses 3 types of spectrums used in calculation, a measurement spectrum, taken before the wafer is polished (See Para [0056]), a sampling spectrum, taken while the wafer is being polished (See Para [0069]), and a reference spectrum, used for comparison (see Para [0069] cited below),
Para [0056] “As a result, the spectrum, produced from the reflected light from the wafer, varies according to the thickness of the upper film. The spectrometer 44 breaks up the reflected light according to the wavelength and measures the intensity of the reflected light at each of the wavelengths. The processor 32 produces the spectrum from the intensity data of the reflected light (i.e., the optical signal) obtained from the spectrometer 44. Hereinafter, a spectrum produced from the reflected light from the wafer W to be polished will be referred to as measurement spectrum. This measurement spectrum is expressed as a line graph (i.e., a spectral waveform) indicating a relationship between the wavelength and the intensity of the light. The intensity of the light can also be expressed as a relative value, such as a reflectance or a relative reflectance.”
Para [0069] “While the target wafer is being polished, the target wafer is irradiated with the light as described above. The processor 32 produces a spectrum from the reflected light from the target wafer, and selects a spectrum group containing a reference spectrum which is closest in shape to the produced spectrum. This spectrum used to select a spectrum group will hereinafter be referred to as sampling spectrum. As with the measurement spectrum, the sampling spectrum is a spectrum produced from the light reflected from the wafer W to be polished. The comparison in shape between the sampling spectrum and the reference spectrum is performed on the basis of a deviation of the reference spectrum from the sampling spectrum. More specifically, the processor 32 calculates the deviation between these two spectra with use of the following equation.”)
the operation controller is configured to select one reference waveform from a plurality of reference Spectrum waveforms accumulated before polishing of the substrate (See Para [0059] “The processor 32 is configured to determine the film thickness from a comparison between the measurement spectrum and a plurality of reference spectra. The optical film-thickness measuring device 25 is coupled to a storage device 58 show in FIG. 1 and FIG. 3. The plurality of reference spectra are stored in this storage device 58. FIG. 7 is a diagram illustrating a process of determining the film thickness from the comparison between the measurement spectrum and the plurality of reference spectra. The processor 32 compares the spectrum, which is produced when the wafer is being polished, with the plurality of reference spectra so as to determine a reference spectrum which is closest in shape to the measurement spectrum, and obtains a film thickness which has been associated with the determined reference spectrum. The reference spectrum which is closest in shape to the measurement spectrum is a spectrum with the smallest difference in the relative reflectance between the reference spectrum and the measurement spectrum.”),
and suggests but does not explicitly disclose
the operation controller is configured to perform an asperity polishing process of polishing the substrate before a film thickness of the substrate reaches an asperity-eliminated film-thickness, and a flat polishing process after the asperity polishing process (Kobayashi discusses in Para [0080] and [0081] (cited below) discusses two halves of the polishing process, one of which being before asperities are removed (the asperity polishing process) and one after (the flat polishing process),
Para [0080] “As the polishing of the target wafer progresses, the measurement spectrum may vary greatly due to some factors, such as a temperature of the target wafer, a change in the shape of the surface of the target wafer, etc. For example, in an initial stage of the polishing process of the target wafer, asperities (or steps) may exist on the surface of the target wafer. When such asperities are removed by the polishing, the measurement spectrum may vary greatly. In a stage where the asperities remain unremoved, the measurement spectrum is relatively unstable depending on the state of the asperities, and may vary between wafers or between areas within the surface of the wafer. In contrast, in a stage where the asperities have been removed by the polishing, a stable measurement spectrum is likely to be obtained.”
Para [0081] “Thus, the processor 32 may produce a sampling spectrum again during the polishing process of the target wafer, and may select again a spectrum group containing a reference spectrum which is closest in shape to this sampling spectrum produced. Since the sampling spectrum produced during the polishing process of the target wafer is substantially the same as the measurement spectrum, the measurement spectrum may be used as the sampling spectrum. After the spectrum group has been selected again, the processor 32 selects a reference spectrum, which is closest in shape to the measurement spectrum, from the spectrum group that has been selected again. By thus selecting the spectrum group again, a more accurate film thickness can be obtained especially in a latter half of the polishing process which has an important significance for a finishing performance.”),
the operation controller is configured to, during the asperity polishing process, determine a plurality of film thicknesses at a plurality of measurement points on the substrate based on a film thickness of reference film data calculated based on a first relational expression (See Para [0088] “In step 4, the processor 32 selects the smallest one of the deviations determined in the step 3 (i.e., the smallest deviation) with respect to each of the measurement points on the target wafer, selects a spectrum group to which a reference spectrum, corresponding to the selected smallest deviation, belongs, and estimates the film thickness of the target wafer from the film thicknesses measured before and after the processing process and the polishing time of the selected spectrum group, and from the polishing time (i.e., the time that has elapsed from the polishing start) of the reference spectrum with the smallest deviation.”),
the operation controller is configured to, during the asperity polishing process, compare the waveform with the selected reference waveform and is configured to determine whether the asperity polishing process should be terminated (See Para [0079] “Once a spectrum group has been selected, the processor 32 produces the measurement spectrum during polishing of the target wafer, and selects a reference spectrum, which is closest in shape to the produced measurement spectrum, from the spectrum group that has been selected as discussed above. More specifically, the processor 32 uses the equation (2) to determine a reference spectrum that is closest in shape to the measurement spectrum, i.e., a reference spectrum with the smallest deviation from the measurement spectrum, and obtains a film thickness that has been associated with the determined reference spectrum. The processor 32 monitors the polishing process of the target wafer based on the determined film thickness, and determines a polishing endpoint at which the film thickness is lower than a predetermined target value. The processor 32 sends a polishing endpoint detection signal to the polishing controller 12, which in turn terminates polishing of the target wafer in response to the polishing endpoint detection signal.”), and
the operation controller is configured to, during the flat polishing process, determine a plurality of film thicknesses at a plurality of measurement points on the substrate based on a film thickness of reference film data calculated based on a second relational expression (Para [0081] cited above discusses repeating the process cited during Para [0079] while using the measurement spectrum as the sampling spectrum, resulting in a second relational expression).
But does not explicitly disclose
a torque measuring device configured to measure a torque for rotating the polishing table, a torque for rotating the polishing head, or a torque for oscillating the polishing head along the polishing surface; and
wherein the operation controller is configured to produce a torque waveform from a measurement value of the torque for rotating the polishing table, a measurement value of the torque for rotating the polishing head, or a measurement value of the torque for oscillating the polishing head along the polishing surface,
Wherein the measured waveforms are torque waveforms
Wherein the asperity polishing process and flat polishing process are distinct separate process.
However, it would be obvious to one of ordinary skill in the art before the effective filling date of the invention to separate the asperity and flat polishing processes into two separate process, as Para [0081] discusses performing the same process but with a different reference spectrum (the measurement spectrum) for the second half of the polishing, as such it would be obvious to terminate the first half which uses the first relational expression at an end point, then initiate the second half, using the second relational expression, as Kobayashi in Para [0081] discusses that doing this would provide more accurate film thickness measurements which would have important significance for finishing performance.
Additionally, Qian discusses a similar polishing process including determining a bulk endpoint time, and discusses that different aspects of the polishing process can be monitored in order to determine an end point (See Para [0123] “In certain implementations, the expected bulk endpoint time is predetermined or calculated as a combination of expected endpoint times of multiple zones. In certain implementations, the bulk endpoint time may be detected using at least one of a motor torque monitoring system, an eddy current monitoring system, a friction monitoring system, or a monochromatic optical system as previously described herein.”) including an optical monitoring system and a motor torque monitoring system (analogous to a measurement value of the torque for rotating the polishing table).
And Fujita discloses a similar polishing process including a torque measuring device configured to measure a torque for rotating the polishing table (Torque measurement unit 9 See Para [0064], a torque for rotating the polishing head, or a torque for oscillating the polishing head along the polishing surface; and
wherein the operation controller is configured to produce a torque waveform from a measurement value of the torque for rotating the polishing table, a measurement value of the torque for rotating the polishing head, or a measurement value of the torque for oscillating the polishing head along the polishing surface (See Para [0064] and [0065] discussing the torque measurement unit and subsequent units for producing and analyzing torque waveforms),
and including determining a polishing endpoint by producing a Torque waveform (See Para [0073] “Next, "detection of the polishing end point according to the torque waveform from which the periodic noise components are removed" will be explained with reference to FIG. 4(a) to 4(c).”) Wherein the Torque waveform of a substrate to be polished (Tb2) is compared to a Torque waveform (Tb1) where the endpoint of Tb1 is presumed to be correct (First See Para [0075] describing the parameters of each torque wave form, with Tb1 having a correct end point E and Tb2 having an erroneous endpoint G, Then See Para [0076]-[0079] describing how both wave forms are differentiated twice, and the changing points Q1 and Q2 are detected to determine the appropriate endpoint time). It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the polishing method of Kobayashi to monitor and analyze torque waveforms instead of the optical spectrum waveforms, as both the monitoring and comparison of both spectrum and torque waveforms for end point detection are known in the art and one of ordinary skill in the art would have found it obvious to substitute optical spectrum analysis for a torque waveform analysis. See MPEP 2143 I B.
Regarding Claim 7, Kobayashi as modified discloses all the limitations of claim 6 and in addition discloses wherein the operation controller is configured to select one reference torque waveform from the plurality of reference torque waveforms based on a film-thickness profile of the substrate before polishing and a type of the substrate (See Para [0078]] “Alternatively, if spectrum groups have been determined using the standalone film-thickness measuring unit or the inline film-thickness measuring unit, it is possible to measure the structure and/or the thickness of the underlying layer of the target wafer with use of the inline film-thickness measuring unit assembled in the polishing apparatus and to select a corresponding spectrum group.”) but does not explicitly disclose selection based off a type of the substrate.
However, Kobayashi does disclose selecting a reference spectrum from a group of reference spectrum by having a process determine which reference spectrum is closest in shape to the measurement spectrum (measurement spectrum of the target wafer, See Para [0059] “The processor 32 compares the spectrum, which is produced when the wafer is being polished, with the plurality of reference spectra so as to determine a reference spectrum which is closest in shape to the measurement spectrum, and obtains a film thickness which has been associated with the determined reference spectrum. The reference spectrum which is closest in shape to the measurement spectrum is a spectrum with the smallest difference in the relative reflectance between the reference spectrum and the measurement spectrum.”). Additionally, Kobayashi discloses only one “type” of substrate.
Fujita discloses that the output of the torque waveform changes drastically when the type of polishing layer on the wafer undergoes a change (First see Para [0084]- [0087] discussing a set-up wherein the conductive film to be polished and the film of a material that is different from the conductive film to be polished are laminated on the wafer. Then See Figs. 5 and 6 and Para [0088] and [0089] discussing the large jump in the torque value at point A where the material forming the layer being polished changes).
It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the spectrum selection process of Kobayashi as modified to ensure that the reference waveform is of a wafer of the same type of the target wafer, as Kobayashi emphasizes selecting a reference spectrum to that is most similar to the target one, and Fujita discloses that wafers comprising different types of materials would give different torque waveforms, and one of ordinary skill in the art before the effective filling date of the invention would find it obvious that selecting a similar reference waveform would involve selecting a reference waveform from a wafer of the same type as Kobayashi in Para [0011] discloses “It is an object of the present invention to provide a polishing method and a polishing apparatus which are capable of measuring an accurate film thickness while eliminating an influence of structural variation of an underlying layer.”.
It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the spectrum selection process of Kobayashi as modified to ensure that the reference waveform is of a wafer of the same type of the target wafer, as Kobayashi emphasizes selecting a reference spectrum to that is most similar to the target one, and one of ordinary skill in the art before the effective filling date of the invention would find it obvious that selecting a similar reference waveform would involve selecting a reference waveform from a wafer of the same type.
Regarding Claim 9, Kobayashi as modified discloses all the limitations of claim 6 and in addition discloses: wherein the operation controller is configured to:
after a predetermined period of time has passed, compare a shape of the torque waveform with a shape of the selected reference torque waveform till a polishing time corresponding to a present polishing time; calculate a degree of coincidence of the shape of the torque waveform and the shape of the selected reference torque waveform (See Para [0092] of Kobayashi (cited below) discussing: wherein after a number of revolutions of the polishing pad passes a predetermined amount (which would be a function of time and speed of the polishing pad), the waveforms for each measurement point on the wafer are compared to the reference waveforms and the deviations are calculated (analogous to calculating a degree of coincidence of the waveform),
[0092] “If the present number of revolutions of the polishing table 3 is larger than the predetermined number of revolutions NM, the measurement spectrum obtained in each of the measurement points on the target wafer is compared with the reference spectra which belong to the optimum spectrum group determined in the step 6, and spectrum deviations are calculated (step 7). A range of the revolutions in which the reference spectra are to be compared is not the revolutions NR in the initial stage of the polishing process, but should be determined in view of the change in the film thickness which occurs as polishing of the wafer progresses, and may be a total revolution range (i.e., a total film-thickness range).”);
compare the calculated degree of coincidence with a predetermined reference degree of coincidence; calculate a difference between polishing time at an asperity-eliminated point estimated from the selected reference torque waveform and the present polishing time when the calculated degree of coincidence is more than or equal to the predetermined reference degree of coincidence (Kobayashi in para [0093] discusses determining a polishing time based on the reference spectrum with the smallest spectrum deviation at a measurement point, and then determining if polishing should be stopped on the basis of if the total polishing time has reached the reference polishing time
[0093] “In step 8, the processor 32 determines a polishing time (i.e., a time that has elapsed from the polishing start) allocated to a reference spectrum with the smallest spectrum deviation calculated in step 7 at each of the measurement points on the target wafer, and calculates a film thickness. In step 9, the processor 32 determines whether the polishing process is to be terminated on the basis of a designated polishing time or a polishing endpoint detection or other criterion. If the polishing process is not to be terminated, then the step 1 is carried out again.”); and
determine that the asperity polishing process should be terminated when polishing time of the substrate has reached a time that is calculated by adding the present polishing time to the difference or a value obtained by multiplying the difference by a coefficient (as previously discussed above, the polishing time is determined then the processor determines when to end the polishing based on the determined polishing time, further see Para [0079] “More specifically, the processor 32 uses the equation (2) to determine a reference spectrum that is closest in shape to the measurement spectrum, i.e., a reference spectrum with the smallest deviation from the measurement spectrum, and obtains a film thickness that has been associated with the determined reference spectrum. The processor 32 monitors the polishing process of the target wafer based on the determined film thickness, and determines a polishing endpoint at which the film thickness is lower than a predetermined target value. The processor 32 sends a polishing endpoint detection signal to the polishing controller 12, which in turn terminates polishing of the target wafer in response to the polishing endpoint detection signal.”).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the operation of the controller such that the determination of when asperity polishing process is terminated (See rejection of claim 6) includes after a predetermined period of time has passed, compare a shape of the torque waveform with a shape of the selected reference torque waveform till a polishing time corresponding to a present polishing time;
calculate a degree of coincidence of the shape of the torque waveform and the shape of the selected reference torque waveform;
compare the calculated degree of coincidence with a predetermined reference degree of coincidence;
calculate a difference between polishing time at an asperity-eliminated point estimated from the selected reference torque waveform and the present polishing time when the calculated degree of coincidence is more than or equal to the predetermined reference degree of coincidence; and
determine that the asperity polishing process should be terminated when polishing time of the substrate has reached a time that is calculated by adding the present polishing time to the difference or a value obtained by multiplying the difference by a coefficient.
As applying the principles of end point determination to the asperity polishing process would allow for a more accurate determination of when the flat polishing process would be started, which would result in improved accuracy regarding film thickness and improve finishing performance as indicated by Kobayashi Para [0081] previously cited.
Regarding claim 10, Kobayashi as modified discloses all the limitations of claim 6 and in addition discloses wherein the operation controller is configured to:
after a predetermined period of time has passed (See Para [0092] of Kobayashi (cited below) discussing: wherein after a number of revolutions of the polishing pad passes a predetermined amount (which would be a function of time and speed of the polishing pad)), compare a shape of the torque waveform with a shape of the selected reference torque waveform till a polishing time corresponding to a present polishing time (the measurement waveform is compared to the reference waveform, See Para [0092] ,
“If the present number of revolutions of the polishing table 3 is larger than the predetermined number of revolutions NM, the measurement spectrum obtained in each of the measurement points on the target wafer is compared with the reference spectra which belong to the optimum spectrum group determined in the step 6, and spectrum deviations are calculated (step 7). A range of the revolutions in which the reference spectra are to be compared is not the revolutions NR in the initial stage of the polishing process, but should be determined in view of the change in the film thickness which occurs as polishing of the wafer progresses, and may be a total revolution range (i.e., a total film-thickness range).”);
and suggests but does not explicitly disclose
calculate a degree of coincidence of the shape of the torque waveform and the shape of the selected reference torque waveform (the deviations between the measurement wave form and the reference waveform are calculated, which is analogous to calculating a degree of coincidence);
compare the calculated degree of coincidence with a predetermined reference degree of coincidence; and instruct the polishing apparatus to change a polishing condition when the calculated degree of coincidence is less than or equal to the predetermined reference degree of coincidence (See Para [0079]
“The processor 32 monitors the polishing process of the target wafer based on the determined film thickness, and determines a polishing endpoint at which the film thickness is lower than a predetermined target value. The processor 32 sends a polishing endpoint detection signal to the polishing controller 12, which in turn terminates polishing of the target wafer in response to the polishing endpoint detection signal. At each point in time during the polishing process of the target wafer, the processor 32 determines manipulated variables (or control variables) for obtaining a predetermined distribution of remaining film thicknesses, on the basis of the film thicknesses determined in the respective areas on the surface of the target wafer. The manipulated variables (or control variables) may be pressure command values for the pressure chambers D1 through D5. The processor 32 sends these pressure command values to the polishing controller 12, which updates the pressures based on the command values that have been sent to the polishing controller 12.”).
It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify process of Kobayashi as modified to manipulate the polishing conditions in reaction to the degree of coincidence with respect to a predetermined degree of coincidence as suggested by Kobayashi as doing so would allow for correction of the polishing process in order to increase the closeness or degree of coincidence between the target wafer waveform and the reference waveform, increasing the accuracy of the polishing process.
Regarding Claim 11, Kobayashi as modified discloses all the limitations of claim 6 and in addition discloses wherein the film-thickness sensor comprises an optical film-thickness sensor or an eddy-current sensor (See Para [0046] “The film thickness sensor 31 is disposed in the polishing table 3, and the processor 32 is coupled to the polishing controller 12. The film thickness sensor 31 rotates together with the polishing table 3 as indicated by arrow A, and obtains the optical signal of the wafer W held on the polishing head 5. The film thickness sensor 31 is coupled to the processor 32 so that the optical signal, obtained by the film thickness sensor 31, is sent to the processor 32.”).
Regarding Claim 12, Kobayashi as modified discloses all the limitations of claim 6 and in addition disclose further comprising a film- thickness measuring device configured to measure a film thickness of the substrate, the film- thickness measuring device being attached to the polishing table (See Para [0046] “The polishing apparatus includes an optical film-thickness measuring device 25 for obtaining a film thickness of the wafer W. This optical film-thickness measuring device 25 has a film thickness sensor 31 for obtaining an optical signal that varies in accordance with the film thickness of the wafer W, and a processor 32 for determining the film thickness from the optical signal. The film thickness sensor 31 is disposed in the polishing table 3, and the processor 32 is coupled to the polishing controller 12.”).
Claim(s) 3 and 8 are rejected under 35 U.S.C. 103 as being unpatentable over Kobayashi (US 20170190020 A1) in view of Qian (US 20140273749 A1) and Fujita (US 20080071414 A1) as modified in claims 1 and 6 respectively and in further view of Birang (US 5846882 A).
Regarding Claim 3, Kobayashi as modified discloses all the limitations of claim 1 but does not explicitly disclose wherein determining whether the asperity polishing process should be terminated comprises determining that the asperity polishing process should be terminated when a present torque of the torque waveform has reached an asperity-eliminated point estimated from the selected reference torque waveform.
However, Birang discloses a similar polishing endpoint detection system, wherein the motor torque is monitored, and compared to a predetermined value to determine when polishing should be ended (See Col 6 Line 57-65 In another embodiment, shown in FIG. 4, rather than summing the current draw of motor 20, the motor torque is summed. The monitor 116 of endpoint detection circuit 50' includes a torque meter 150. The torque meter 150 is placed on drive shaft 108 (see FIG. 2). The output of torque meter 150 is connected to signal processor 118. The signal processor sums the output of the torque meter. This sum may be compared to a baseline sum to determine the polishing endpoint.”), wherein the predetermined value is a reference value (See Col 4 Line 9-19 “When the sum equals a predetermined reference or baseline sum, which represents the quantity of material to be removed, the polishing endpoint is achieved. The reference sum is determined experimentally for a given layer material or substrate material for given polishing parameters. Specifically, a plurality of substrates may be polished under a variety of polishing conditions or parameters. The polishing parameters may include the pad material, rotational speed of the polishing pad and carrier head, substrate load, and slurry composition.”).
It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the polishing process of Kobayashi as modified such that determining whether the asperity polishing process should be terminated comprises determining that the asperity polishing process should be terminated when a present torque of the torque waveform has reached an asperity-eliminated point estimated from the selected reference torque waveform. Birang discloses determining endpoint by comparing a present value to a reference value is advantageous as “The described invention provides a convenient mechanism for monitoring the rate at which the material is removed from the substrate and the total quantity of material removed, without the need to remove the substrate from the polishing surface and without interruption of the polishing operation. The invention also provides a mechanism to detect a polishing endpoint where an underlying layer of a different material is not exposed. Therefore, the method and apparatus described herein may be used to determine polishing endpoint for any material being polished and for raw wafer polishing, without disturbing the polishing operation.” See Col 6 Line 11-21.
Regarding Claim 8, Kobayashi as modified discloses all the limitations of claim 6 and in addition discloses wherein the operation controller is configured to determine that the asperity polishing process should be terminated when a present torque of the torque waveform has reached an asperity-eliminated point estimated from the selected reference torque waveform.
However, Birang discloses a similar polishing endpoint detection system, wherein the motor torque is monitored, and compared to a predetermined value to determine when polishing should be ended (See Col 6 Line 57-65 “In another embodiment, shown in FIG. 4, rather than summing the current draw of motor 20, the motor torque is summed. The monitor 116 of endpoint detection circuit 50' includes a torque meter 150. The torque meter 150 is placed on drive shaft 108 (see FIG. 2). The output of torque meter 150 is connected to signal processor 118. The signal processor sums the output of the torque meter. This sum may be compared to a baseline sum to determine the polishing endpoint.”), wherein the predetermined value is a reference value (See Col 4 Line 9-19 “When the sum equals a predetermined reference or baseline sum, which represents the quantity of material to be removed, the polishing endpoint is achieved. The reference sum is determined experimentally for a given layer material or substrate material for given polishing parameters. Specifically, a plurality of substrates may be polished under a variety of polishing conditions or parameters. The polishing parameters may include the pad material, rotational speed of the polishing pad and carrier head, substrate load, and slurry composition.”).
It would be obvious to one of ordinary skill in the art before the effective filling date of the invention to modify the polishing process of Kobayashi as modified such that determining whether the asperity polishing process should be terminated comprises determining that the asperity polishing process should be terminated when a present torque of the torque waveform has reached an asperity-eliminated point estimated from the selected reference torque waveform. Birang discloses determining endpoint by comparing a present value to a reference value is advantageous as “The described invention provides a convenient mechanism for monitoring the rate at which the material is removed from the substrate and the total quantity of material removed, without the need to remove the substrate from the polishing surface and without interruption of the polishing operation. The invention also provides a mechanism to detect a polishing endpoint where an underlying layer of a different material is not exposed. Therefore, the method and apparatus described herein may be used to determine polishing endpoint for any material being polished and for raw wafer polishing, without disturbing the polishing operation.” See Col 6 Line 11-21.
Conclusion
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/T.J.M./ Examiner, Art Unit 3723
/DAVID S POSIGIAN/ Supervisory Patent Examiner, Art Unit 3723
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