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 § 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.
Claims 1-2, 4-5, 9-10, 12-13, 15, 18 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Walmsley et al. (NPL – Micro-G Silicon Accelerometer Using Surface Electrodes) in view of Guo (US 7736931 B1).
Considering claim 1, Walmsley discloses a MEMS structure comprising:
- a mechanical layer that extends parallel to a reference device plane, wherein:
- the mechanical layer includes a static electrode (Stator Electrode) and a movable electrode (Proof Mass Electrode) configured to move relative to the static electrode and parallel to the reference device plane (Figure 1, Page 972, III Next Generation Sensor).
- the static electrode and the movable electrode form a capacitor having capacitance that varies based on an overlap between the static electrode and the movable electrode (Page 972, III Next Generation Sensor, “Motion of the proof mass in response to external acceleration changes the area of overlap and thus the capacitance between the electrodes”),
- the mechanical layer includes a first silicon layer and a second silicon layer (Page 972, III Next Generation Sensor, “Three silicon wafers are bonded together to form a sealed cavity around a proof mass”),
- the movable electrode is in the first silicon layer and the static electrode is in the second silicon layer (Figure 1),
- the movable electrode is separated from the static electrode by a first gap in an interface between the first silicon layer and the second silicon layer (Figure 1), and
- the movable electrode and the static electrode include one or more comb fingers that extend parallel to the reference device plane (Figure 2; Page 972, “Interdigitated surface electrodes”; Figure 1 shows the surface electrodes extending in the same plane as the reference device plane).
The invention by Walmsley utilizes thin film bonding material between the first and second layers of the mechanical layer, and thus fails to disclose that the first and second silicon layers are in part directly bonded to one another.
However, Guo discloses an accelerometer having a mechanical layer that includes a first silicon layer 108 (Figures 10-13; Column 5, lines 42-56) and a second silicon layer 124 (Figures 5, 9 and 10; Column 6, lines 20-33) which are in part directly bonded to one another (Figure 10; Column 7, line 57 - Column 8, line 2).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to utilize silicon layers that are directly bonded to one another, as taught by Guo, in the invention by Walmsley. The motivation for doing so, as understood in the art, is to provide enhanced thermal stability by matching the coefficients of thermal expansion of the two mechanical layers, thus reducing thermal induced strain on the accelerometer package.
Considering claim 2, Walmsley discloses that the overlap of the static electrode and the movable electrode corresponds to projections of the static electrode and the movable electrode onto the reference device plane (Figure 1; Page 972, III Next Generation Sensor).
Considering claim 4, Walmsley discloses a substrate layer (Figure 1, Stator wafer).
Considering claim 5, Walmsley discloses that the one or more comb fingers of the movable electrode extend from one or more beams suspended from the substrate layer or the mechanical layer by one or more spring elements that enable back and forth movement of the one or more beams beam parallel to the reference plane (Figures 1-2; Page 972, III Next Generation Sensor, “flexural suspension is defined by etching through the MEMS wafer” and “high aspect ratio flexures”).
Considering claim 9, Walmsley discloses a cap layer (Cap Wafer) bonded to the second silicon layer, such that the movable electrode (MEMS Wafer) is separated from the cap layer by a second gap patterned into the interface between the second silicon layer and the cap layer (Figure 1; Page 972).
Considering claim 10, Walmsley discloses that the capacitance of the capacitor is configured to detect an acceleration parallel to the reference device plane (Page 972, III Next Generation Sensor, “The sensor is a variable capacitor, using surface electrodes between the MEMS wafer and the stator wafer. Motion of the proof mass in response to external acceleration changes the area of overlap and thus the capacitance between the electrodes”).
Considering claim 12, Walmsley discloses a MEMS structure including a mechanical layer that extends parallel to a reference device plane, the MEMS structure comprising:
- a static electrode (Stator Electrode) and a movable electrode (Proof Mass Electrode) configured to move relative to the static electrode and parallel to the reference device plane (Figure 1, Page 972, III Next Generation Sensor);
- a capacitor formed by the static and movable electrodes having capacitance that varies based on an overlap between the static electrode and the movable electrode (Page 972, III Next Generation Sensor, “Motion of the proof mass in response to external acceleration changes the area of overlap and thus the capacitance between the electrodes”);
- a first silicon layer and a second silicon layer (Page 972, III Next Generation Sensor, “Three silicon wafers are bonded together to form a sealed cavity around a proof mass”);
- wherein the movable electrode is in the first silicon layer and the static electrode is in the second silicon layer (Figure 1),
- wherein the movable electrode is separated from the static electrode by a first gap between the first silicon layer and the second silicon layer (Figure 1),
- the movable electrode and the static electrode include one or more comb fingers that extend parallel to the reference device plane (Figure 2; Page 972, “Interdigitated surface electrodes”; Figure 1 shows the surface electrodes extending in the same plane as the reference device plane).
The invention by Walmsley utilizes thin film bonding material between the first and second layers of the mechanical layer, and thus fails to disclose that the first and second silicon layers are in part directly bonded to one another.
However, Guo discloses an accelerometer having a mechanical layer that includes a first silicon layer 108 (Figures 10-13; Column 5, lines 42-56) and a second silicon layer 124 (Figures 5, 9 and 10; Column 6, lines 20-33) which are in part directly bonded to one another (Figure 10; Column 7, line 57 - Column 8, line 2).
Therefore, it would have been obvious to one of ordinary skill in the art to utilize silicon layers that are directly bonded to one another, as taught by Guo, in the invention by Walmsley. The motivation for doing so, as understood in the art, is to provide enhanced thermal stability by matching the coefficients of thermal expansion of the two mechanical layers, thus reducing thermal induced strain on the accelerometer package.
Considering claim 13, Walmsley discloses that the overlap of the static electrode and the movable electrode corresponds to projections of the static electrode and the movable electrode onto the reference device plane (Figure 1; Page 972, III Next Generation Sensor).
Considering claim 15, Walmsley discloses a substrate layer (Figure 1, Stator wafer), wherein the one or more comb fingers of the movable electrode extend from one or more beams suspended from the substrate layer or the mechanical layer by one or more spring elements that enable back and forth movement of the one or more beams beam parallel to the reference plane (Figures 1-2; Page 972, III Next Generation Sensor, “flexural suspension is defined by etching through the MEMS wafer” and “high aspect ratio flexures”).
Considering claim 18, Walmsley discloses a cap layer (Cap Wafer) bonded to the second silicon layer, such that the movable electrode (MEMS Wafer) is separated from the cap layer by a second gap patterned into the interface between the second silicon layer and the cap layer (Figure 1; Page 972).
Considering claim 20, Walmsley discloses a method for manufacturing a MEMS structure having a static electrode and a movable electrode configured to form a capacitor with a capacitance that varies based on movement of the movable electrode in relation to the static electrode and parallel to a reference device plane, the method including:
- patterning a recess to a first silicon wafer (Figure 1; Page 972, III Next Generation Sensor, “The proof mass and flexural suspension is defined by etching through the MEMS wafer);
- bonding the first silicon wafer to a second wafer (Figure 1, MEMS wafer bonded to Stator wafer);
- patterning static electrodes to the second silicon wafer (Figures 1 and 2; Pages 971, 972, II. First Generation Sensors “variable capacitor is formed by patterning interdigitated or comb electrodes in the device layer between the proof mass and surrounding fixed structure”, and III. Next Generation Sensors, “The sensor is a variable capacitor, using surface electrodes between the MEMS wafer and the stator wafer”);
- patterning movable electrodes to the first silicon wafer (Figures 1 and 2; Pages 971, 972, II. First Generation Sensors “variable capacitor is formed by patterning interdigitated or comb electrodes in the device layer between the proof mass and surrounding fixed structure”, and III. Next Generation Sensors, “The sensor is a variable capacitor, using surface electrodes between the MEMS wafer and the stator wafer”); and
- bonding a capping wafer (Cap Wafer) to the first silicon wafer (MEMS wafer), and
- the movable electrode and the static electrode include one or more comb fingers that extend parallel to the reference device plane (Figure 2; Page 972, “Interdigitated surface electrodes”; Figure 1 shows the surface electrodes extending in the same plane as the reference device plane).
The invention by Walmsley utilizes thin film bonding material between the first and second silicon layers, and thus fails to disclose that the first and second silicon layers are in part directly bonded to one another and that the second silicon layer is bonded to a handle wafer.
However, Guo discloses an accelerometer a first silicon layer 124 (Figures 5, 9 and 10; Column 6, lines 20-33) and a second silicon layer 108 (Figures 10-13; Column 5, lines 42-56) that are in part directly bonded to one another (Figure 10; Column 7, line 57 - Column 8, line 2), wherein the second silicon wafer 108 is bonded to handle wafer 112 (Figure 3; Column 5, lines 46-48).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to utilize silicon layers that are directly bonded to one another, as taught by Guo, in the invention by Walmsley. The motivation for doing so, as understood in the art, is to provide enhanced thermal stability by matching the coefficients of thermal expansion of the two mechanical layers, thus reducing thermal induced strain on the accelerometer package.
Claims 6-8 and 16-17 are rejected under 35 U.S.C. 103 as being unpatentable over Walmsley et al. (NPL – Micro-G Silicon Accelerometer Using Surface Electrodes) in view of Guo (US 7736931 B1), as applied to claims 5 and 15, respectively, above, and further in view of Liukku et al. (US 2015/0316581 A1).
Considering claim 6, Walmsley, as modified by Guo, discloses a square proof mass, having a plurality of comb sets, separated by trenches from an outer substrate, thus establishing an outer frame, whereby two-dimensional movement is enabled by positioning flexure suspensions on at least two perpendicular surfaces of the frame, but the combination fails to explicitly disclose four beams and oppositely supported first and second electrode comb sets.
However, Walmsley, as modified by Guo, fails to explicitly disclose that the one or more beams are part of a rectangular frame of four beams, and one beam of the frame supports movable comb fingers of a first electrode comb set and an opposite beam of the frame supports movable comb fingers of a second electrode comb set.
However, Liukku teaches a capacitive MEMS device having a rotor frame 15 flexibly suspended, via spring structures 4,4a,4b over a stator 1 and attached to a substrate 2, whereby the rotor frame 15 is a four-beam rectangular frame having first and second electrode comb sets 7 supported by opposite beams (Figure 1; [0046-54]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to utilize the four-beam frame structure of Liukku having opposite beams supporting respective first and second comb electrodes sets, in the invention by Walmsley, as modified by Guo. The motivation for doing so is to provide better common-mode rejection and increased sensitivity, as is generally understood in the art of differential output accelerometers.
Considering claim 7, Walmsley discloses that the static comb fingers of the first electrode comb set and static comb fingers of the second electrode comb set are separately coupled to a voltage source and are separated from opposing movable comb fingers by the first gap to form two capacitors configured for differential detection (Figure 3, Page 973, IV Electronics). Additionally, while not relied upon at this time, Applicant’s Admitted Prior Art, in [0033] of the originally filed specification, renders this limitation obvious as well.
Considering claim 8, Walmsley discloses that each movable comb finger is configured to overlap two static comb fingers to form two capacitors that respond in opposite phase to motions of the frame (Figure 3, this is the concept relied upon for the measurement of acceleration).
Considering claim 16, Walmsley, as modified by Guo, discloses a square proof mass, having a plurality of comb sets, separated by trenches from an outer substrate, thus establishing an outer frame, whereby two-dimensional movement is enabled by positioning flexure suspensions on at least two perpendicular surfaces of the frame, but the combination fails to explicitly disclose four beams and oppositely supported first and second electrode comb sets.
However, Walmsley, as modified by Guo, fails to explicitly disclose that the one or more beams are part of a rectangular frame of four beams, and one beam of the frame supports movable comb fingers of a first electrode comb set and an opposite beam of the frame supports movable comb fingers of a second electrode comb set.
However, Liukku teaches a capacitive MEMS device having a rotor frame 15 flexibly suspended, via spring structures 4,4a,4b over a stator 1 and attached to a substrate 2, whereby the rotor frame 15 is a four-beam rectangular frame having first and second electrode comb sets 7 supported by opposite beams (Figure 1; [0046-54]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to utilize the four-beam frame structure of Liukku having opposite beams supporting respective first and second comb electrodes sets, in the invention by Walmsley, as modified by Guo. The motivation for doing so is to provide better common-mode rejection and increased sensitivity, as is generally understood in the art of differential output accelerometers.
Considering claim 17, Walmsley discloses that the static comb fingers of the first electrode comb set and static comb fingers of the second electrode comb set are separately coupled to a voltage source and are separated from opposing movable comb fingers by the first gap to form two capacitors configured for differential detection (Figure 3, Page 973, IV Electronics), wherein each movable comb finger is configured to overlap two static comb fingers to form two capacitors that respond in opposite phase to motions of the frame (Figure 3, this is the concept relied upon for the measurement of acceleration). Additionally, while not relied upon at this time, Applicant’s Admitted Prior Art, in [0033] of the originally filed specification, renders this limitation obvious as well.
Claims 11 and 19 are rejected under 35 U.S.C. 103 as being unpatentable over Walmsley et al. (NPL – Micro-G Silicon Accelerometer Using Surface Electrodes) in view of Guo (US 7736931 B1), as applied to claims 1 and 12, respectively, above, and further in view of Geiger et al. (US 9709596 B2).
Considering claim 11, Walmsley discloses applying opposing carrier signals to the stationary stators to nullify alignment offset errors. While it is assumed this will generate motion, even minutely, of the movable electrodes, Walmsley fails to explicitly disclose that this is the result. Accordingly, the invention by Walmsley, as modified by Guo fails to disclose that the capacitance of the capacitor is configured to actuate the movable electrode into a motion parallel to the reference device plane.
However, Geiger teaches the use of a “reset voltage”, whereby voltage applied to stationary electrodes will actuate movement of the movable electrodes to return an inertial mass to a neutral position and/or provide closed-loop control (Column 2, lines 31-44; Column 7, line 63 – Column 8, line 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to actuate the movable electrode into a motion parallel to the reference device plane through capacitance between the stationary and movable electrodes, as taught by Geiger, in the invention by Walmsley, as modified by Guo. According to Geiger, the closed-loop control of the positioning of the electrodes relative to one another is placed into effect by applying a voltage to the electrodes, thus providing the alignment control suggested by Walmsley.
Considering claim 19, Walmsley discloses applying opposing carrier signals to the stationary stators to nullify alignment offset errors. While it is assumed this will generate motion, even minutely, of the movable electrodes, Walmsley fails to explicitly disclose that this is the result. Accordingly, the invention by Walmsley, as modified by Guo fails to disclose that the capacitance of the capacitor is configured to actuate the movable electrode into a motion parallel to the reference device plane.
However, Geiger teaches the use of a “reset voltage”, whereby voltage applied to stationary electrodes will actuate movement of the movable electrodes to return an inertial mass to a neutral position and/or provide closed-loop control (Column 2, lines 31-44; Column 7, line 63 – Column 8, line 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to actuate the movable electrode into a motion parallel to the reference device plane through capacitance between the stationary and movable electrodes, as taught by Geiger, in the invention by Walmsley, as modified by Guo. According to Geiger, the closed-loop control of the positioning of the electrodes relative to one another is placed into effect by applying a voltage to the electrodes, thus providing the alignment control suggested by Walmsley.
Response to Arguments
Applicant's arguments filed 6/11/2026 have been fully considered but they are not persuasive.
Applicant presents and or argues points A-F on pages 6-11 of response. The Examiner shall address each issue, as deemed necessary.
Considering point A, the Examiner generally agrees with the statement of the claimed invention, but takes notice of unclaimed features, thus moot points, pertaining to the method of manufacture of the claimed comb fingers.
Considering point B on page 7, Applicant argues that Walmsley fails to discloses interdigitated comb fingers, because it discloses flat, thin-film surface electrodes deposited on opposing surfaces of the MEMS wafer and the stator wafer. However, it is clear from Figure 2, specifically, in combination with Figure 1, the that surface electrodes are “interdigitated surface electrodes”. Figure 2, of Walmsley, has been presented below for further consideration.
It is clear from the Figure 2 image and the statement in the caption of Figure 2 on page 972 that the surface electrodes are interdigitated. Furthermore, they are in fact comb electrodes, as best shown in Figure 2, which project from the surface of the MEMS wafer and Stator wafer, as best shown in Figure 1. Applicant is invited to review the full text version of the Walmsley reference to verify color-shading of the electrodes in Figure 1.
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Continuing, Applicant argues that the two-axis group of surface electrodes on the proof mass only cooperated with a single “planar surface electrode on the opposing stator wafer”. However, this is incorrect, as evidenced by Page 973, IV. Electronics. In this section Walmsley expressly states that, for each axis, there are 4 electrodes, 2 on the MEMs wafer (already shown in Figure 2), and 2 on the Stator wafer. It is clear, then, that the stator wafer is a corresponding surface electrode pair, similar to that shown in Figure 2, as further shown by Figures 1 and 3 (schematic). Therefore, Applicant’s arguments against the lack of corresponding moveable and static comb electrodes in Walmsley is unpersuasive.
Considering point C on page 8, Applicant points out that Walmsley discusses comb electrodes with respect to the “First Generation Sensors” review. The Examiner agrees to this statement, but has not relied on any teachings from this section of the document. Therefore, this argument is moot as it is not applicable to the rejection being made.
Considering point D, also on Page 8, similar to point C, Applicant argues that Walmsley teaches away from Comb-Finger combination in the same review.
The Examiner agrees that the Walmsley’s alternative use of surface electrodes is in view of the disadvantages of the specific comb-finger electrodes of the First Generation Sensor, as outlined by the Applicant on Page 9 of the response.
However, it is specifically noted that the broadest reasonable interpretation of the comb fingers, in view of the specification, is clearly already shown in Figure 2 of Walmsley. The Examiner relies on the interdigitated comb-finger structure shown and discussed with respect to that figure as the basis for the rejection. Applicant has not provided any evidence to show that the surface electrodes, in their disclosed configuration, cannot be considered comb-finger type electrodes.
The Examiner has not suggested modification to Walmsley to include comb-finger electrodes, since the Examiner has stated and continues to maintain they are already present. Accordingly, since no suggestion of modification to the comb-finger electrodes has been made, there would not be a “teaching away” to rely upon because there is no suggested modification from which to teach away.
Applicant’s argument is found to be unpersuasive because the interdigitated comb-finger electrodes of the movable MEMS wafer and the static Stator wafer are in fact comb-finger electrodes, as clearly shown and discussed in the Figures and details thereof, thus no modification is being suggested that would be dissuaded by the discloses of Walmsley.
Considering point E, Applicant argues that there is a lack of rationale to modify Walmsley to include the claimed comb-finger electrodes. As has already been stated, above, there is no modification required to add a feature to Walmsley that is already present. This argument is not persuasive as no attempt to modify the electrodes has been suggested by the Examiner. Continuing, Guo does not purport to modify the electrodes, and Applicant has not argued against the teachings of Guo or the underlying rationale to modify the type of bonding. Accordingly, this argument is non-persuasive as well.
Considering point F, Applicant cursorily asserts that all depended claims are allowable based on their dependency upon claims 1 or 12. This argument is not persuasive as the Examiner has maintained the rejections of claims 1 and 12.
Accordingly, all rejections have been maintained and this action is made FINAL.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Jonathan M Dunlap whose telephone number is (571)270-1335. The examiner can normally be reached Mon-Fri 10AM - 7PM.
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/JONATHAN M DUNLAP/Primary Examiner, Art Unit 2855 June 26, 2026
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