DETAILED ACTION
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 .
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claim(s) 1-3 and 16 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Lutker-Lee.
Lutker-Lee discloses protective layers and method of formation during plasma etching processes. Lutker-Lee discloses an embodiment that is illustrated in Figures 2A-2C. Lutker-Lee discloses that FIG. 2A illustrates a patterned mask layer overlying an etchable layer, FIG. 2B illustrates a protective layer formed over the patterned mask layer and the etchable layer, and FIG. 2C illustrates the patterned mask layer and the etchable layer after an etching process. (Para, 0029). Lutker-Lee then describes the processes associated with Figures 2A-2C in greater detail.
Lutker-Lee discloses illustrates in FIG. 2A, a workpiece 200 at an initial stage of a method of plasma etching includes an etchable layer 20 overlying a substrate 10. (Para, 0030). Lutker-Lee discloses the substrate 10 may be any suitable material or combination of materials at any stage of processing. (Para, 0030). Lutker-Lee discloses the substrate 10 includes underlying layers such as a metallization layer and may include a backside metallization layer. (Para, 0030). Lutker-Lee discloses the underlying layers may include device layers and the substrate 10 includes a semiconductor material or may be a wafer. (Para, 0030). Lutker-Lee discloses the etchable layer 20 may directly contact the substrate 10 or additional layers may be included between the substrate 10 and the etchable layer. (Para, 0031; Fig.2A). Lutker-Lee discloses the etchable layer 20 is a layer configured to be etched by the method of plasma etching and it may include a dielectric (e.g., an oxide, a nitride, etc.), and is a low-κ dielectric or ULK dielectric in some embodiments. (Para, 0031; Fig.2A). Lutker-Lee also discloses in some embodiments, the etchable layer 20 is a semiconducting material such as silicon, germanium, a III-V semiconductor, a II-VI semiconductor, and the like. (Para, 0031; Fig.2A). Lutker-Lee also discloses the etchable layer 20 may include a metal such as aluminum, copper, tungsten, and others. (Para, 0031).
Lutker-Lee discloses a patterned mask layer 230 overlies the etchable layer 20. (Para, 0032). Lutker-Lee discloses the patterned mask layer 230 may be formed using any suitable combination of deposition method, growth technique, lithographic technique, direct write method, multi-patterning techniques and the patterned mask layer 230 is a later of a single material or it may include multiple layers of similar or different materials. (Para, 0032). Lutker-Lee discloses the patterned mask layer 230 may include dielectric materials, metal materials, and/or semiconductor materials and in various embodiments, the patterned mask layer 230 includes a dielectric layer and includes an oxide or a nitride in some embodiments or a ceramic material. (Para, 0032: Fig.2A). Lutker-Lee discloses the patterned mask layer 230 is patterned to include features with upper surfaces 234 defining openings 32 that are vertically aligned with exposed regions 22 of the etchable layer 20. (Para, 0032; Fig.2A). Lutker-Lee discloses the exposed regions 22 include exposed surfaces 24 of the etchable layer 20. (Para, 0032; Fig.2A). These disclosures and the illustrations of Figure 2A teach the limitation of claim 1 and 16, ‘ A method of manufacturing a semiconductor device, the method comprising: forming a patterned hardmask over an underlying target layer on a substrate…’ Lutker-Lee discloses in a second embodiment a workpiece 300 at an initial stage of a method of plasma etching includes an etchable layer 20 overlying a substrate 10. (Para, 0045). Lutker-Lee discloses a first mask layer 336 is included overlying the etchable layer 20 and the first mask layer 336 may include a metal such as a transition metal (e.g. titanium, ruthenium, hafnium, etc.) and in some embodiments the first mask layer 336 is a nitride while in other embodiments the first mask layer 336 is an oxide. (Para, 0045). Lutker-Lee discloses the first mask layer 336 is a titanium nitride (TiN) layer but it may also be a titanium oxide layer, ruthenium oxide, hafnium oxide, among others. (Para, 0045). These disclosures teach the limitation of claims 2-3.
Lutker-Lee discloses the workpiece 200 may be provided as described at the initial stage of a method of plasma etching, where it is received into a processing chamber of a plasma processing apparatus, with openings 32 that reveal exposed surfaces 24 of an etchable layer 20 supported by a substrate 10. (Para, 0033; Fig. 2A). Lutker-Lee illustrates in FIG. 2B, the workpiece 200 after the formation of a protective layer 40, which overlies both the patterned mask layer 230 and the etchable layer 20. (Para, 0035; Fig.2B). Lutker-Lee discloses the protective layer 40 is formed in-situ (i.e. in place) during the method of plasma etching. (Para, 0035; Fig.2B). These disclosures and the illustrations of Figure 2B teach the limitation of claims 1and 16, ‘ A method of manufacturing a semiconductor device, the method comprising: …and performing plasma fabrication operations in parallel on the patterned hardmask and underlying target layer in a plasma etching chamber…’
Lutker-Lee discloses the protective layer 40 may have a higher etch selectivity than the etchable layer 20 to a particular etchant used to etch the etchable layer 20 so that the etchant may etch the etchable layer 20 at a higher rate than the protective layer 40. (Para, 0036; Fig.2B). Lutker-Lee discloses the protective layer 40 may be a conformal layer in some embodiments and its thickness is different above the upper surfaces 234 than above the exposed surfaces 24. (Para, 0036; Fig.2B). Lutker-Lee discloses the protective layer 40 has a first thickness 61 above the upper surfaces 234 and a second thickness 62 above the exposed surfaces 24 and in some embodiments the first thickness 61 is greater than the second thickness 62, between about 1 nm and about 10 nm and is about 5 nm in one embodiment. (Para, 0036; Fig.2B).
Lutker-Lee discloses the protective layer 40 is illustrated as forming on sidewalls of the patterned mask layer 230, but there is no requirement for this to be the case. (Para, 0036). Lutker-Lee also discloses the protective layer 40 may be formed using any suitable process in-situ in the processing chamber, such as silicon precursor techniques (e.g. using SiCl4, SiF4, etc.), in-situ atomic layer deposition (ALD), sputter deposition, plasma polymerization (e.g. using precursors such as CH4, etc.), direct current superposition (DCS) techniques, and the like. (Para, 0037; Fig.2B). Lutker-Lee also discloses the protective layer 40 may include any suitable material, the choice of which may depend on the details of a given process such as etch type, composition of the etchable layer 20, composition of the patterned mask layer 230, throughput requirements, cost, complexity, and others. (Para, 0038; Fig.2B). Lutker-Lee discloses the protective layer 40 may include silicon (e.g. may be silicon (Si), silicon oxide (SiO2), silicon nitride (Si3N4), etc.). (Para, 0038; Fig.2B). Lutker-Lee also discloses the protective layer 40 includes an organic material such as an organic polymer like a fluorocarbon polymer. (Para, 0038; Fig.2B). These disclosures teach the limitation of claims 1 and 16, ‘ A method of manufacturing a semiconductor device, the method comprising: …using a plasma etch gas and a selective source gas…’
Lutker-Lee then illustrates in FIG. 2C, the workpiece 200 includes recesses 250 in the etchable layer 20 after a plasma etching step is performed. (Para, 0039; Fig.2C). Lutker-Lee discloses the plasma etching step may utilize any suitable plasma etching technique including a continuous wave plasma etching technique as well as ALE or QALE may be used. (Para, 0039; Fig.2C). Lutker-Lee discloses the protective layer 40 is fully removed while the patterned mask layer 230 and the etchable layer 20 are each partially removed. (Para, 0040: Fig.2C). Lutker-Lee explains the partial removal of the etchable layer 20 results in the recesses 250 and the partial removal of the patterned mask layer 230 reduces the thickness to a second vertical thickness 264. (Para, 0040; Fig.2C). Lutker-Lee discloses the majority of the patterned mask layer 230 remains after the etching step, for example the second vertical thickness 264 is greater than 50% of the first vertical thickness 263. (Para, 0040). Lutker-Lee discsoes the corner selectivity of the patterned mask layer 230 is advantageously improved using the protective layer 40 compared to conventional processes so the shape of the corners of the patterned mask layer 230 is less rounded than those of conventional methods of plasma etching (Para, 0041; Fig.1B). Lutker-Lee explains the improved selectivity afforded by the use of the protective layer may advantageously improve one or a combination of the pattern integrity during the etching step, fidelity of the transferred pattern, improved (e.g. straighter) profile of the recesses 250, reduction or elimination of footing and other undesirable etching artifacts. (Para, 0041; Fig.2C). These disclosures and the illustrations of Figure 2C teach the limitations of claim 1, ‘ A method of manufacturing a semiconductor device, the method comprising: …the plasma fabrication operations including: forming a protective cap on the patterned hardmask; and removing portions of the underlying target layer that are not covered by the patterned hardmask.’ These disclosures and the illustrations of Figure 2C also teach the limitation of claim 16, ‘ A method of manufacturing a semiconductor device, the method comprising: …the plasma fabrication operations including: reducing an amount of patterned hardmask etching during the plasma fabrication operations by forming a protective cap on the patterned hardmask; forming a combined hardmask comprising the patterned hardmask and the protective cap; and removing portions of the underlying target layer that are not covered by the patterned hardmask.
Lutker-Lee discloses the recesses 250 include a vertical depth 65 and a first lateral width 66. (Para, 0042). Additionally, Lutker-Lee discloses, corner selectivity may be more important for small feature sizes and/or dense patterns; therefore, the patterned mask layer 230 may include regularly spaced recesses 250 that each include the first lateral width 66 and separated by a second lateral width 67, both which may be small. (Para, 0042). Lutker-Lee discloses in some embodiments one or both of the first lateral width 66 and the second lateral width 67 are less than about 25 nm and one embodiment, the first lateral width is about 20 nm and the second lateral width is about 20 nm. (Para, 0042).
Lutker-Lee discloses, in relation to the shape of the openings 32, the recesses 250 may have any suitable shape such as lines, holes, etc. (Para, 0043). Lutker-Lee discloses the aspect ratio of the recesses 250 may be large and the recesses 250 may be deep trenches. (Para, 0043). In some embodiments, the vertical depth 65 is larger than the first lateral width 66. In one embodiment, the vertical depth 65 is greater than or equal to about twice the first lateral width 66. In various embodiments, the vertical depth 65 is between about 35 nm and about wo nm and is about 40 nm in one embodiment.
Therefore, claims 1-3 and 16 are anticipated by the disclosures and illustrations of Lutker-Lee.
Claim Rejections - 35 USC § 103
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 17-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Lutker-Lee as applied to claims 1-3 and 16 in paragraph 4 above, and further in view of Baier (US 2004/0038541).
As discussed above, Lutker-Lee discloses the protective layer 40 has a first thickness 61 above the upper surfaces 234 and a second thickness 62 above the exposed surfaces 24 and in some embodiments the first thickness 61 is greater than the second thickness 62, between about 1 nm and about 10 nm and is about 5 nm in one embodiment. (Para, 0036; Fig.2B). Lutker-Lee also discloses Lutker-Lee discloses the recesses 250 may be deep trenches. In some embodiments, the vertical depth 65 is larger than the first lateral width 66. In one embodiment, the vertical depth 65 is greater than or equal to about twice the first lateral width 66. (Para, 0042). Lutker-Lee also discloses the vertical depth 65 is between about 35 nm and about wo nm and is about 40 nm in one embodiment. (Para, 0042). These disclosures of Lutker-Lee contemplate the limitations of claim 17. Lutker-Lee also discloses corners represent the intersection of feature edges; therefore, corner selectivity may be especially important when attempting to improve pattern fidelity. (Para, 0019). Lutker-Lee explains, smaller feature sizes, corners become a larger percentage of the total and features may be more easily merged during the etching process. (Para, 0019). Lutker-Lee further explains, small holes and thin lines may be particularly susceptible to merging or breaking due to low corner selectivity. (Para, 0019). Moreover, Lutker-Lee discloses that with an advantageous increase in etch selectivity of mask layer during the etching process, the corner selectivity during the etching process may be improved. (Para, 0026). These disclosures of Lutker-Lee contemplate the limitation of claim 18.
Still, the disclosures of Lutker-Lee as discussed above fail to teach and/or suggest the limitation of claim 19, ‘ The method of claim 16, wherein the plasma etching chamber uses inductively coupled plasma (ICP), capacitively coupled plasma (CCP), or electron cyclotron resonance (ECR) plasma.’ However, the disclosures of Lutker-Lee further in view of the disclosures of Baier provides such teachings.
Baier discloses a method of etching a hardmask layer and underlying metal layer on a semiconductor substrate. Baier illustrates an exemplary layer stack that is to be patterned by plasma etching. (Para, 0024; Fig.1). Baier discloses on a SiO2 base layer 4 which is usually provided on a semiconductor wafer, especially a silicon wafer, 10 nm of Ti, 400 nm of an alloy containing 99.5% Al and 0.5% Cu, 5 nm of Ti and 40 nm of TiN are deposited as a metal layer stack 3. (Para, 0024; Fig.1). Baier discloses that trenches having a width of approximately 140 nm are to be etched into the metal layer stack 3. (Para, 0024; Fig.1). Baier discloses to selectively etch the trenches, first, 180 nm of a SiON layer 2 are deposited as a hard mask material, followed by 490 nm of a generally used photoresist material 1. (Para, 0024). Baier discloses a pattern is photo-lithographically defined into the photoresist layer 1, then the SiON layer 2 is etched in a plasma etching process, and finally, the metal layer stack 3 is etched in another plasma etching process. (Para, 0024; Fig.1-4).
Baier discloses etchant for the hard mask layer, usually include a mixture of a fluorine containing gas such as CF4 or CHF3 and Cl2 is used. (Para, 0026). Baier discloses as an etchant for etching the metal layer stack, conventionally a mixture of a chlorine containing gas such as BCl3, Cl2 and, optionally, N2 and CHF3 is used. (Para, 0026). Baier discloses the hard mask opening step and the metal etching step are performed in a single plasma processing chamber in two different steps using different etchants so the two steps are performed subsequently without breaking vacuum lock. (Para, 0029). Baier discloses the plasma processing apparatus that can be used for carrying out the present invention may be any known plasma processing apparatus such as devices for dry etching, plasma etching, reactive ion etching or electron cyclotron resonance etching. (Para, 0030). Baier further discloses, the process of the present invention may be performed in a transmission coupled plasma (TCP) etching apparatus, where the energy for sustaining the plasma is inductively coupled to a reactor but in a different plasma etching apparatus, the energy could be also capacitively coupled. (Para, 0031). The disclosures of Lutker-Lee further in view of these disclosures teach and/or suggest the limitation of claim 19.
Baier discloses an etchant source gas, that is a mixture of a fluorine containing gas such as CF4 (tetrafluoromethane) or CHF3 (trifluoromethane), argon and a small amount (approximately 5 to 20% based on the flow rate of the fluorine containing gas) of oxygen is used. (Para, 0036). Baier discloses typical flow rates to be employed are 100 sccm of CF4, 150 sccm of argon and 5 to 20 sccm of O2 (oxygen). (Para, 0036). Baier discloses the pressure prevailing in the plasma processing chamber is in the order of 1 to 1.5 Pa, the RF power applied to the top electrode 7 is set to approximately 600 to 1000 W, and the RF power applied to the chuck 13 is set to approximately 150 to 300 W which are preferred settings for transformer coupled plasma (TCP) tools. (Para, 0036). Baier also discloses the radio frequency employed is 13.56 MHz. From these disclosures of Baier, one of ordinary skill in the art would reasonably understand that parameters such as pressure, temperature, power, frequency and other parameters set in the plasma etch chamber are specific to the type of plasma chamber or tool used. Therefore, the disclosures of Lutker-Lee further in view of these disclosures of Baier, contemplate the limitations of claim 20.
It would have been obvious to one of ordinary skill in the art at the time of filing the present application by Applicant modify the disclosures of Lutker-Lee further in view of the disclosures of Baier, because both are directed to methods of patterning metal layers and hardmask layers in the same process chamber and Baier discloses advantageous plasma processing chambers that can be in the process disclosed in Lutker-Lee for a more efficient device formation process.
Allowable Subject Matter
Claims 4-7 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter: The disclosures of Lutker-Lee in view of Baier fail to teach and/or suggest the limitation of claim 4, ‘The method of claim 2, wherein the selective source gas comprises a chemical compound that includes Tungsten (W) when the patterned hardmask comprises silicon.’ The disclosures of Lutker-Lee in view of Baier fail to teach and/or suggest the limitation of claim 5, ‘The method of claim 2, wherein the selective source gas comprises a chemical compound that includes the metal in the chemical compound from which the patterned hardmask is formed.’ The prior art fails to provide other relevant disclosures which are properly combinable with Lutker-Lee and/or Baier to teach and/or suggest the limitation of claims 4 and 5. Claims 6-7 depend directly from claim 5. Therefore, claims 4-7 include allowable subject matter.
The following is an examiner’s statement of reasons for allowance: The disclosures of Lutker-Lee as discussed above teach and/or suggest the limitation of claim 8, ‘ A method of manufacturing a semiconductor device, the method comprising: forming a patterned hardmask over an underlying target layer on a substrate; and performing plasma fabrication operations in parallel on the patterned hardmask and underlying target layer in a plasma etching chamber using a plasma etch gas and a selective source gas…the plasma fabrication operations comprising: … forming a protective cap on the patterned hardmask …and removing portions of the underlying target layer that are not covered by the patterned hardmask using the plasma etch gas…’ Still, the disclosures of Lutker-Lee fail to teach the limitation of claim 8, ‘ A method of manufacturing a semiconductor device, the method comprising: … wherein the selective source gas comprises a chemical compound comprising a halogen gas that can be dissociated into a metal and a halogen, the plasma fabrication operations comprising: dissociating the metal and the halogen in the selective source gas… and the halogen that has been dissociated.’ The disclosures of Baier fail to cure the deficiencies of Lutker-Lee to teach and/or suggest these limitations of claim 8. Moreover, the prior art fails to provide other relevant disclosures which cure the deficiencies of Lutker-Lee and/or Baier. Therefore, independent claim 8 and claims 9-15 depending therefrom are allowable.
Conclusion
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/CALEEN O SULLIVAN/Primary Examiner, Art Unit 2899