MEMS RESONATOR AND MANUFACTURING METHOD

Response After Non-Final This Office action is in response to the amendment filed on 8/13/2026. Claims 1-18 are pending in the application. Claims 1-17 are rejected. Claims 1-2, 4, 6, 8, 11-12, and 15-17 are currently amended. Claim 18 is withdrawn. 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 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. Response to Arguments The applicant's arguments filed August 13, 2026 have been fully considered and are respectfully found persuasive in part and unpersuasive in part. The applicant argues the following: [1] Title and claim objections and the 112 rejection have been addressed and should be withdrawn. [2] Prior art of record fails to teach two layers of single-crystalline silicon. Regarding [1], the examiner respectfully agrees and the title and claim objections and the 112 rejection raised in the most recent office action are hereby withdrawn. Regarding [2], the examiner respectfully disagrees because the prior art of record discloses the matched element can be “any other suitable material that is electrically conductive.” First, the prior art of record does not limit layer L1 to polysilicon. Second, “any other suitable material that is electrically conductive” includes single-crystalline silicon. Therefore, the prior art of record discloses the claimed two layers of single-crystalline silicon. DETAILED ACTION Claim Rejections - 35 USC § 102 The following is a quotation of the appropriate paragraphs of AIA 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. Claims 1-17 are rejected under AIA 35 U.S.C. 102(a)(1) as being anticipated by Saarela et al. (U.S. Publication No. 20220166406; hereinafter “Saarela”). Regarding claim 1, Saarela discloses a microelectromechanical system (MEMS) resonator, comprising: a first layer of single-crystalline silicon (Fig. 12, L1; [0100]); a second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]); and a piezoelectric layer (Fig. 12, L2; [0099]) in between (Fig. 12) the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) and the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]). Regarding claim 2, Saarela discloses the MEMS resonator of claim 1, wherein the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) is an uppermost layer (Fig. 12) above the piezoelectric layer (Fig. 12, L2; [0099]) and the second layer of single-crystalline silicon (Fig. 12, L3-L4) and is used (Fig. 12; [0101]-[0102]) as an electrode (Fig. 12; [0101]-[0102]) for the MEMS resonator (Fig. 12; [Abstract]). Regarding claim 3, Saarela discloses the MEMS resonator of claim 1, wherein an average impurity doping of either the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) or the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) or both the first layer (Fig. 12, L1; [0100]) and the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) is 2*1019cm-3 or more (Fig. 12; [0012]). Regarding claim 4, Saarela discloses the MEMS resonator of claim 1, wherein a <100> crystalline direction (Fig. 12; [0012]) in the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) is in a plane (Fig. 12; [0012]) of the first layer of single-crystalline silicon (Fig. 12, L1; [0100]), or deviates less than 10 degrees therefrom (Fig. 12; [0012]), and a <100> crystalline direction (Fig. 12; [0012]) in the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) is in a plane (Fig. 12; [0012]) of the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]), or deviates less than 10 degrees therefrom (Fig. 12; [0012]). Regarding claim 5, Saarela discloses the MEMS resonator of claim 1, wherein a <100> crystalline direction (Fig. 12; [0012]) in the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) is parallel with (Fig. 12; [0012]), or deviates less than 10 degrees from (Fig. 12; [0012]), a <100> crystalline direction (Fig. 12; [0012]) in the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]). Regarding claim 6, Saarela discloses the MEMS resonator of claim 1, wherein the crystalline directions (Fig. 12; [0012]) in the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) and in the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) are parallel (Fig. 12; [0012]) or deviate at most 10 degrees (Fig. 12; [0012]). Regarding claim 7, Saarela discloses the MEMS resonator of claim 1, wherein the temperature coefficient (Fig. 12; [0110]; [0112]) of the resonance frequency (Fig. 12; [0110]; [0112]) of either the first layer (Fig. 12, L1; [0100]) or the second layer of single-crystalline silicon layer (Fig. 12, L3-L4; [0102]) is positive (Fig. 12; [0112]). Regarding claim 8, Saarela discloses the MEMS resonator of claim 1, wherein the crystalline c-axis of the piezoelectric layer (Fig. 12, L2; [0099]) is either parallel (Fig. 12; [0012]) to the direction orthogonal (Fig. 12; [0012]) to the plane (Fig. 12; [0012]) defined by (Fig. 12; [0012]) the piezoelectric layer (Fig. 12, L2; [0099]) or at an angle larger than zero (Fig. 12; [0012]) and smaller than 90 degrees (Fig. 12; [0012]) with respect to (Fig. 12; [0012]) the direction orthogonal (Fig. 12; [0012]) to the plane (Fig. 12; [0012]). Regarding claim 9, Saarela discloses the MEMS resonator of claim 1, wherein the resonance mode (Fig. 12; [0019]) of the MEMS resonator (Fig. 12) is an in-plane resonance mode (Fig. 12; [0019]) and the thickness of the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) and the thickness (Fig. 12; [0100]-[0102]) of the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) are equal within 20% or less (Fig. 12; [0100]-[0102]). Regarding claim 10, Saarela discloses the MEMS resonator of claim 1, wherein the resonance mode (Fig. 12; [0019]) of the MEMS resonator (Fig. 12) is a length-extensional mode resonance (Fig. 12; [0024]; [0051] [0089]). Regarding claim 11, Saarela discloses the MEMS resonator of claim 1, wherein the resonance mode (Fig. 12; [0019]) of the MEMS resonator (Fig. 12) is an out-of-plane flexural mode (Fig. 12; [0019]) and the thickness (Fig. 12; [0100]-[0102]) of the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) differs (Fig. 12; [0100]-[0102]) from the thickness (Fig. 12; [0100]-[0102]) of the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) at least by 20% or at least by 50% (Fig. 12; [0100]-[0102]). Regarding claim 12, Saarela discloses the MEMS resonator of claim 1, comprising a release trench (Fig. 12; [0090]; [0103]) surrounding (Fig. 12; [0090]; [0103]) the MEMS resonator (Fig. 12) and extending through (Fig. 12; [0090]; [0103]) all material layers (Fig. 12; [0090]; [0103]) of the resonator (Fig. 12). Regarding claim 13, Saarela discloses the MEMS resonator of claim 1, comprising an interconnection (Figs. 8/12, 120; [0106]) providing an electrical path (Figs. 8/12, 120; [0106]) to the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) through an opening (Figs. 8/12, 120; [0106]) in the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) and in the piezoelectric layer (Fig. 12, L2; [0099]). Regarding claim 14, Saarela discloses the MEMS resonator of claim 1, comprising an intermediate material layer (Fig. 12, L4’; [0111]) between the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) and the piezoelectric layer (Fig. 12, L2; [0099]) or between (Fig. 12, L4’; [0111]) the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) and the piezoelectric layer (Fig. 12, L2; [0099]). Regarding claim 15, Saarela discloses the MEMS resonator of claim 1, comprising an additional material layer (Fig. 12, L5) on a bottom surface (Fig. 12, bottom surface of L3-L4; [0102]) of the second layer of single-crystalline silicon (Fig. 12, L3-L4; [0102]) the additional material layer (Fig. 12, L5) facing (Fig. 12) a cavity (Fig. 12, cavity in L5) that separates (Fig. 12) the MEMS resonator (Fig. 12) from a substrate (Fig. 12, L6). Regarding claim 16, Saarela discloses the MEMS resonator of claim 1, comprising a vertical trench (Figs. 8/12, 120) extending from end to end (Figs. 8/12, 120) of the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) and vertically through (Figs. 8/12, 120) the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) the vertical trench (Figs. 8/12, 120) electrically isolating (Figs. 8/12, 120) two regions (Fig. 12, two regions of L1; [0100]) of the first layer of single-crystalline silicon (Fig. 12, L1; [0100]). Regarding claim 17, Saarela discloses the MEMS resonator of claim 1, comprising fine-tuning material layers (Fig. 12, L7-L8; [0108]) on top (Fig. 12) of the first layer of single-crystalline silicon (Fig. 12, L1; [0100]) for resonance frequency trimming (Fig. 12, L7-L8; [0107]-[0108]). 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 extension fee 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 date of this final action. Any inquiry concerning this communication should be directed to MONICA MATA whose telephone number is (571) 272-8782. The examiner can normally be reached on Monday thru Friday from 7:30 AM to 5:00 PM. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Dedei Hammond, can be reached on (571) 270-7938. The fax phone number for the organization where this application or proceeding is assigned is (571) 273-8300. Information regarding the status of an application may be obtained from the Patent Application Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). /MONICA MATA/ Patent Examiner, Art Unit 2837 14 October 2026 /EMILY P PHAM/Primary Examiner, Art Unit 2837