Microelectromechanical systems devices and their manufacturing methods

Abstract

A microelectromechanical system (MEMS) device and a method for forming the same are disclosed. The MEMS device includes a movable comb-like structure within a cavity located within a housing and a stationary structure fixed to the housing. The movable comb-like structure includes a comb shaft portion and movable comb fingers projecting laterally from the comb shaft portion. The movable comb-like structure includes a metallic portion. The movable structure and the stationary structure are used to generate an electrical output signal based on lateral movement of the movable structure relative to the stationary structure.

Description

Technical Field

[0001] This disclosure relates to a microelectromechanical system device and a method for forming the same. Background Technology

[0002] Micro-electro-mechanical systems (MEMS) devices comprise devices that can be fabricated using semiconductor technology to form mechanical and electrical characteristics. MEMS devices can include moving parts with micrometer or submicrometer dimensions and mechanisms for electrically coupling the moving parts to electrical signals. The electrical signals can be input signals that cause movement on the moving parts or output signals generated by the movement of the moving parts. MEMS devices are useful devices that can be integrated with other devices, such as semiconductor devices, to function as sensors or actuators. Summary of the Invention

[0003] According to some embodiments of this disclosure, a microelectromechanical system (MEMS) device includes a movable comb-like structure and a stationary structure. The movable comb-like structure is located in a cavity within a housing and includes a comb shaft portion and a plurality of movable comb fingers. The movable comb fingers project laterally from the comb shaft portion, wherein the movable comb-like structure includes a metallic portion. The stationary structure is fixed to the housing, wherein the movable comb-like structure and the stationary structure are configured to generate an electrical output signal based on lateral movement of the movable comb-like structure relative to the stationary structure.

[0004] According to some embodiments of this disclosure, a microelectromechanical system (MEMS) device includes a movable comb-like structure and a stationary structure. The movable comb-like structure is located in a cavity within a housing and includes a comb shaft portion and a plurality of movable comb fingers. The movable comb fingers project laterally from the comb shaft portion, wherein the movable comb-like structure includes a first metallic material portion. The stationary structure is fixed to the housing and includes a second metallic material portion having the same material composition as the first metallic material portion, wherein the movable comb-like structure and the stationary structure are used to generate an electrical output signal based on a capacitance change between the movable comb-like structure and the stationary structure.

[0005] According to some embodiments of this disclosure, a method for forming a microelectromechanical system (MEMS) device includes the following steps: forming a first trench and a second trench in a semiconductor matrix material layer; depositing at least one trench filling material in the first trench and the second trench, wherein the at least one trench filling material comprises a metallic material; and removing a portion of the semiconductor matrix material layer surrounding the first trench and the second trench, wherein multiple portions of the at least one trench filling material in the first trench include a movable comb structure, and multiple portions of the at least one trench filling material in the second trench include a stationary structure, and wherein the movable comb structure and the stationary structure are used to generate an electrical output signal based on a capacitance change between the movable comb structure and the stationary structure. Attached Figure Description

[0006] When read in conjunction with the accompanying drawings, the following detailed description is the best way to understand the nature of this disclosure. It should be noted that, in accordance with standard industry practice, the various features are not drawn to scale. In practice, for clarity of explanation, the dimensions of the various features may be arbitrarily increased or decreased.

[0007] Figure 1A This is a vertical cross-sectional view of an exemplary structure comprising a semiconductor matrix material layer after the formation of a recessed cavity, according to an embodiment of the present disclosure.

[0008] Figure 1B For along Figure 1A A horizontal cross-sectional view of an exemplary structure in the horizontal plane B–B';

[0009] Figure 2 This is a vertical cross-sectional view of an exemplary structure after a diffusion barrier spacer is formed at the periphery of the groove cavity according to an embodiment of the present disclosure.

[0010] Figure 3 This is a vertical cross-sectional view of an exemplary structure after the formation of a semiconductor oxide substrate according to an embodiment of the present disclosure;

[0011] Figure 4 This is a vertical cross-sectional view of an exemplary structure after the removal of the diffusion barrier spacer according to an embodiment of the present disclosure.

[0012] Figure 5A This is a vertical cross-sectional view of an exemplary structure after the semiconductor matrix material layer is bonded to the cap substrate according to an embodiment of the present disclosure.

[0013] Figure 5B For along Figure 5A The horizontal cross-sectional view of an exemplary structure in plane B–B'. The hinged vertical plane A–A' is... Figure 5A The plane of the vertical cross-section;

[0014] Figure 6A This is a vertical cross-sectional view of an exemplary structure after the formation of comb-shaped grooves and edge grooves according to an embodiment of the present disclosure;

[0015] Figure 6B According to Figure 6A The horizontal cross-sectional view of the exemplary structure. The hinged vertical plane A–A' is... Figure 6A The plane of the vertical cross-section;

[0016] Figure 7A This is a vertical cross-sectional view of an exemplary structure after the formation of the comb-shaped grooves and wall structure according to an embodiment of the present disclosure;

[0017] Figure 7B For along Figure 7A The horizontal cross-sectional view of an exemplary structure in plane B–B'. The hinged vertical plane A–A' is... Figure 7A The plane of the vertical cross-section;

[0018] Figures 8A to 8H Vertical cross-sectional views of various configurations of the active comb fingers according to various embodiments of this disclosure;

[0019] Figures 9A to 9H The following are vertical cross-sectional views of various configurations of the stationary comb fingers according to various embodiments of the present disclosure;

[0020] Figure 10A This is a vertical cross-sectional view of an exemplary structure after the metal material portion has been formed, according to an embodiment of this disclosure;

[0021] Figure 10B For along Figure 10A The top view of an exemplary structure with plane B–B'. The hinged vertical plane A–A' is... Figure 10A The plane of the vertical cross-section;

[0022] Figure 11A This is a vertical cross-sectional view of an exemplary structure after the formation of a patterned etched mask layer, according to an embodiment of the present disclosure.

[0023] Figure 11B for Figure 11A A partial perspective top view of an exemplary structure. The hinged vertical plane A–A' is... Figure 11A The plane of the vertical cross-section;

[0024] Figure 12A This is a vertical cross-sectional view of an exemplary structure after selectively isotropically etching the unmasked portion of a semiconductor matrix material layer for a patterned etch mask layer, a comb structure, an edge trench filling structure, and a semiconductor oxide substrate, according to an embodiment of the present disclosure.

[0025] Figure 12B For along Figure 12A The horizontal cross-sectional view of an exemplary structure in plane B–B'. The hinged vertical plane A–A' is... Figure 12A The plane of the vertical cross-section;

[0026] Figure 13A A vertical cross-sectional view of an exemplary structure after the removal of the patterned etched mask layer according to an embodiment of the present disclosure;

[0027] Figure 13B According to Figure 13A The top view of the exemplary structure. The hinged vertical plane A–A' is the plane of the vertical cross-sectional view in Figure 13A;

[0028] Figure 14 This is a vertical cross-sectional view of an accelerometer formed according to an embodiment of the present disclosure by removing the cap substrate and isolating the exemplary structure into a plurality of accelerometers.

[0029] Figure 15 The flowchart illustrates a set of processing steps that can be executed to form a MEMS device according to embodiments of the present disclosure.

[0030] [Symbol Explanation]

[0031] 10: Semiconductor matrix material layer

[0032] 10A: Central mass block section

[0033] 10F: Semiconductor frame

[0034] 10M: Semiconductor matrix layer

[0035] 11: Diffusion barrier spacer

[0036] 12A, 12B: Board material

[0037] 13: Groove cavity

[0038] 13R: Recessed bottom surface

[0039] 13S: Sidewall

[0040] 20: Cap substrate

[0041] 30, 40: Comb-like structure

[0042] 31, 41, 51: comb-like grooves

[0043] 32, 42, 110, 120, 130: Metallic material parts

[0044] 33, 52, 82, 87, 92, 97: Dielectric pads

[0045] 34, 44, 48: Semiconductor Materials Section

[0046] 36, 46: Second metallic material section

[0047] 37: Photoresist layer

[0048] 38: Second Semiconductor Material Section

[0049] 43: Extended section of comb groove

[0050] 50: Barrier Structure

[0051] 51: Inspection quality block obstruction groove

[0052] 54: Barrier Conductive Filler Material Section

[0053] 61: Cavity

[0054] 67: Etching masking material layer

[0055] 81, 86, 91, 96: Edge grooves and channels

[0056] 84, 89, 94, 99: Trench filling material section

[0057] 80: Close-proximity wall structures

[0058] 85: Suspended wall structure

[0059] 90: Intermediate wall structure

[0060] 95: Distal wall structure

[0061] 100: Accelerometer

[0062] 101: First horizontal surface

[0063] 102: Second horizontal surface

[0064] 301: First active comb-like structure

[0065] 302: Second active comb-like structure

[0066] 401: First stationary comb structure

[0067] 402: Second static comb structure

[0068] 311: First internal comb-like groove

[0069] 312: Second internal comb-like groove

[0070] 411: First outer comb-shaped groove

[0071] 412: Second external comb-shaped groove

[0072] 1500: Flowchart

[0073] 1510, 1520, 1530: Steps

[0074] A_PM: Area

[0075] A–A': Hinged vertical plane

[0076] B–B': Horizontal plane

[0077] CPI1, CPI2: Internal comb-like pattern

[0078] CPO1, CPO2: External comb-like pattern

[0079] CSEP: Comb shaft extension pattern

[0080] hd1: First horizontal direction

[0081] hd2: Second horizontal direction

[0082] MSP: Mirror-symmetric plane

[0083] PMBP: Inspection Quality Block Barrier Pattern

[0084] t: thickness Detailed Implementation

[0085] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided subject matter. Specific examples of elements and configurations are described below to simplify this disclosure. Of course, these specific examples are merely illustrative and not intended to be limiting. For example, the formation of a first feature above or on a second feature in the following description may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where an additional feature may be formed between the first and second features so that the first and second features do not need to be in direct contact. Furthermore, reference numerals and / or letters may be repeated in various instances in this disclosure. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0086] Additionally, for ease of description, spatial relative terms (such as "below," "under," "bottom," "above," "upper," and the like) may be used herein to describe the relationship between one component or feature and another, as illustrated in the accompanying drawings. Besides the orientations depicted in the drawings, the spatial relative terms are also intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and therefore the spatial relative descriptive terms used herein may be interpreted accordingly.

[0087] MEMS devices can have many useful applications. For example, CMOS image sensors can include motion stabilizers. Motion stabilizers can detect motion experienced by the image sensor and compensate for that motion in the generation of the detected image. MEMS devices can detect vibrations as changes in capacitance occur when structures within a MEMS device move toward or away from a stationary structure, causing changes in capacitance between the structures. Because the structures within a MEMS device are designed to move, they can be prone to breakage when subjected to excessive movement, such as when the device is dropped. Therefore, it may be necessary to increase the strength of the moving structures within a MEMS device.

[0088] Generally, the embodiments disclosed herein pertain to a microstructure comprising a micro-electromechanical system (MEMS) device. The MEMS device includes a precision verification mass for measuring the movement of an object to which the MEMS device is attached. For example, the MEMS device may include an accelerometer. The embodiments disclosed herein can be used to form a high-precision verification mass for a MEMS device.

[0089] Specifically, trenches can be formed on one side of the semiconductor matrix material layer. The trenches may include, for example, a first trench and a second trench. In one embodiment, the trenches may include comb-shaped trenches having a corresponding comb-shaped horizontal cross-sectional shape. These trenches are referred to herein as comb-shaped trenches. A comb-shaped trench may include two interdigitated pairs of corresponding inner comb-shaped trenches and corresponding outer comb-shaped trenches. A first portion (i.e., the central mass block portion) of the semiconductor matrix material layer, which will subsequently be patterned into a test mass block, may be located between the two inner comb-shaped trenches. The outer comb-shaped trenches may be connected by comb-axis extension trenches. The outer comb-shaped trenches and the comb-axis extension trenches together surround all the inner comb-shaped trenches and define the lateral boundaries for a cavity subsequently formed. A common comb-axis cavity portion may define the boundary of a cavity in which the subsequently formed moving parts are laterally constrained.

[0090] A dielectric liner layer and at least one conductive filler material can be deposited in the comb trenches, and excess portions of the dielectric liner layer and at least one conductive filler material located above a horizontal plane containing the top surface of the semiconductor matrix material layer can be removed by a planarization process. According to some embodiments, multiple conductive filler materials can be used to provide an enhanced fill profile and increase the mechanical and electrical properties of the electrode to be formed. The remaining portion of the dielectric liner layer and at least one conductive filler material in each comb trench includes a comb structure. The comb structure includes a movable comb structure formed in an inner comb trench and a stationary comb structure formed in an outer comb trench. The movable structure, including a central mass block portion, the movable comb structure, and the stationary comb structure, can be detached from the second semiconductor oxide substrate. The forked comb structure includes a capacitor structure that produces a capacitance change when the movable structure moves relative to the stationary structure containing the stationary comb structure. The microstructure may include an accelerometer that can detect the acceleration of the system to which the microstructure is attached. The use of multiple materials for filling the comb trenches can provide structural and electrical benefits to the microstructure. The various aspects of the embodiments disclosed herein are described in more detail below.

[0091] refer to Figure 1A and Figure 1B The illustration shows a semiconductor matrix material layer 10, which can be provided as a planar structure including a first horizontal surface 101 on a first side and a back surface (i.e., a second horizontal surface) with a consistently uniform thickness on a second side, but is not necessarily limited thereto. The semiconductor matrix material layer 10 includes a first semiconductor material, which can be a single-crystal semiconductor material or a polycrystalline semiconductor material. In one embodiment, the semiconductor matrix material layer 10 may include a single-crystal semiconductor layer, such as a single-crystal silicon layer. The uniform thickness of the semiconductor matrix material layer 10 can be in the range of 30 micrometers to 1 mm, such as in the range of 100 micrometers to 600 micrometers. Although the area used to form a single accelerometer is in... Figure 1A and Figure 1B The diagram illustrates that a two-dimensional array of accelerometers can be formed on a single wafer. Therefore, Figure 1A and Figure 1B The pattern shown in the figure can be repeated in a two-dimensional array pattern above the semiconductor matrix material layer 10.

[0092] A photoresist layer (not shown) may be applied over a first horizontal surface 101 of the semiconductor matrix material layer 10. The photoresist layer may be photolithographically patterned to form an opening having a general shape of an inspection quality block (also referred to as the central quality block portion) to be subsequently formed. In one embodiment, the periphery of the opening in the photoresist layer may be offset outward from the periphery of the inspection quality block, subsequently formed by a lateral offset distance. The lateral offset distance may, for example, range from 0.5 micrometers to 30 micrometers. Therefore, the area of ​​the opening in the photoresist layer may have a larger area than the area of ​​the inspection quality block (A_PM) to be subsequently formed. In a non-limiting illustrative example, the opening in the photoresist layer may have an elongated rounded rectangular shape, with a longitudinal dimension ranging from 300 micrometers to 6 millimeters and a lateral dimension ranging from 30 micrometers to 600 micrometers, but smaller and larger dimensions may also be used.

[0093] The pattern of openings in the photoresist layer can be transferred to the upper portion of the semiconductor substrate layer 10 by an etching process, which can include anisotropic or isotropic etching. A recessed cavity 13 can be formed vertically from the first horizontal surface 101 of the semiconductor substrate layer 10. The recessed horizontal surface can be located at the bottom of the recessed cavity 13. The recess depth of the recessed cavity 13 can range from 0.3 micrometers to 10 micrometers, such as from 0.6 micrometers to 5 micrometers, but smaller and larger recess depths can also be used. The recessed cavity 13 has sidewalls 13S that connect the recessed bottom surface 13R of the recessed cavity 13 to the unrecessed portion of the first horizontal surface 101 of the semiconductor substrate layer 10. The photoresist layer can then be removed, for example, by ashing.

[0094] refer to Figure 2 A diffusion barrier spacer 11 comprising a diffusion barrier material (also referred to as a barrier spacer) can be formed at the periphery of the recessed cavity 13. The diffusion barrier spacer 11 comprises a material that prevents oxygen from diffusing through it. For example, the diffusion barrier spacer 11 may comprise and / or may be substantially composed of silicon nitride. However, other suitable materials are also within the scope of this disclosure. In some embodiments, the diffusion barrier spacer 11 may be any material and is used to protect the sidewalls 13S of the recessed cavity 13 from the subsequently formed semiconductor oxide substrate (SOD). Figure 3The diffusion barrier spacer 11 can be formed, for example, by conformally depositing a diffusion barrier material layer (such as a silicon nitride layer or a metal nitride layer containing a metal nitride material (e.g., TaN, TiN, or WN)) on the recessed bottom surface 13R and sidewalls 13S of the recessed cavity 13 and on the unrecessed portion of the first horizontal surface 101 of the semiconductor matrix material layer 10. In other embodiments, the diffusion barrier spacer 11 can be formed by partially modifying the semiconductor matrix material layer 10. The thickness of the diffusion barrier material layer can be in the range of 30 nm to 200 nm, but smaller and larger thicknesses can also be used. The diffusion barrier material can be anisotropically etched to remove the horizontal portion of the diffusion barrier material layer deposited on the recessed bottom surface of the recessed cavity and on the unrecessed portion of the first horizontal surface 101 of the semiconductor matrix material layer 10. The remaining vertical portion of the diffusion barrier material layer constitutes the diffusion barrier spacer 11. In one embodiment, each sidewall 13S of the recessed cavity 13 may contact the corresponding outer sidewall of the diffusion barrier spacer 11. The diffusion barrier spacer 11 may have a generally tubular shape and thus be topologically isomorphic to the torus, i.e., it may be continuously deformed into the torus without creating new holes or destroying pre-existing holes.

[0095] refer to Figure 3 An oxidation process can be performed to transform the solid exposed surface portion of the semiconductor matrix material layer 10 at the bottom of the recessed cavity 13 and on the unrecessed portion of the semiconductor matrix material layer 10 into a semiconductor oxide substrate (12A, 12B). For example, a thermal oxidation process can be performed to transform the solid exposed surface portion of the semiconductor matrix material layer 10 into a semiconductor oxide portion. A diffusion barrier spacer 11 prevents oxygen atoms from diffusing through it to the semiconductor matrix material layer 10 that forms the sidewalls of the recessed cavity 13 during the oxidation process. The thermal oxidation process can use a dry oxidation process, a wet oxidation process, or a rapid thermal oxidation process. For example, dry oxidation is a thermal oxidation process using O2 as an oxidant. Wet oxidation is a thermal oxidation process using H2O as an oxidant. Rapid thermal oxidation is a thermal oxidation process that uses a single wafer processing chamber and provides thermal oxidation at high temperatures.

[0096] A first semiconductor oxide substrate 12A can be formed at the bottom of the recessed cavity 13 by transforming the underlying surface portion of the semiconductor matrix material layer 10 into a dielectric semiconductor oxide material portion via an oxidation process. A second semiconductor oxide substrate 12B can be formed on the first horizontal surface 101 of the unrecessed portion of the semiconductor matrix material layer 10 by transforming the underlying surface portion of the semiconductor matrix material layer 10 into an additional dielectric semiconductor oxide material portion. The thickness of the first and second semiconductor oxide substrates (12A, 12B) can be in the range of 50 nm to 500 nm, but smaller and larger thicknesses can also be used. In one embodiment, where the semiconductor matrix material layer 10 contains any material other than silicon (such as silicon-germanium alloy or III-V compound semiconductor materials), the first and second semiconductor oxide substrates (12A, 12B) can include silicon oxide or an oxide of the semiconductor material of the semiconductor matrix material layer 10 and / or can be substantially composed of silicon oxide or an oxide of the semiconductor material of the semiconductor matrix material layer 10.

[0097] refer to Figure 4 The diffusion barrier spacer 11 can be selectively removed from the materials of the first and second semiconductor oxide substrates (12A, 12B) and the semiconductor matrix material layer 10. For example, if the diffusion barrier spacer 11 comprises silicon nitride, a wet etching process using hot phosphoric acid can be performed to selectively remove the diffusion barrier spacer 11 from the materials of the first and second semiconductor oxide substrates (12A, 12B) and the semiconductor matrix material layer 10. The semiconductor surface of the semiconductor matrix material layer 10 can be substantially exposed at the sidewalls of the recess cavity 13.

[0098] refer to Figure 5A and Figure 5B The semiconductor matrix material layer 10 can be bonded to the cap substrate 20 via a second semiconductor oxide substrate 12B. The cap substrate 20 may include a semiconductor substrate, a conductive substrate, a dielectric substrate, or a combination thereof. The cap substrate 20 may have sufficient thickness to provide structural support during subsequent thinning of the semiconductor matrix material layer 10. For example, the thickness of the cap substrate 20 may be in the range of 60 micrometers to 1 mm, but thicker or thinner cap substrates may also be used.

[0099] The cap substrate 20 can then be attached to the semiconductor matrix material layer 10. In one embodiment, the horizontal top surface of the cap substrate 20 comprises a semiconductor oxide material that can be bonded to the second semiconductor oxide substrate 12B. The second semiconductor oxide substrate 12B can be attached to the cap substrate 20 by bonding the second semiconductor oxide substrate 12B to the cap substrate 20. Suitable bonding methods can be used to bond the second semiconductor oxide substrate 12B to the horizontal top surface of the cap substrate 20. For example, if the cap substrate 20 includes a semiconductor top surface, a semiconductor-to-oxide bonding method, such as silicon-to-silicon oxide bonding, can be used to bond the cap substrate 20 to the second semiconductor oxide substrate 12B. Alternatively, if the cap substrate 20 includes a semiconductor oxide top surface (such as a silicon oxide top surface), an oxide-to-oxide bonding method, such as silicon-to-silicon oxide bonding, can be used to bond the cap substrate 20 to the second semiconductor oxide substrate 12B. The semiconductor-to-oxide bonding or oxide-to-oxide bonding can be performed by an annealing process at an elevated temperature, which can be in the range of 200 degrees Celsius to 600 degrees Celsius.

[0100] The semiconductor substrate layer 10 can then be thinned by grinding, polishing, and / or etching the back surface of the semiconductor substrate layer 10 located on the opposite side of the second semiconductor oxide substrate 12B. The final step of the thinning process may include a polishing step that provides a horizontally flat surface on the back side (i.e., the polished side) of the semiconductor substrate layer 10. This polished back surface of the semiconductor substrate layer 10 is referred to herein as the second horizontal surface 102. The thickness t of the semiconductor substrate layer 10, as measured between the second horizontal surface 102 and the first horizontal surface 101 contacting the second semiconductor oxide substrate 12B, can range from 2 micrometers to 60 micrometers, such as from 4 micrometers to 30 micrometers, but smaller and larger thicknesses are also possible. The lower limit for the thickness t of the semiconductor substrate layer 10 can be imposed by the minimum capacitance requirement of the subsequently formed capacitor structure, while the upper limit for the thickness t of the semiconductor substrate layer 10 can be imposed by the process capability and economic feasibility of the subsequent etching process used to form comb-shaped trenches through the semiconductor substrate layer 10.

[0101] refer to Figure 6A and Figure 6BThe photoresist layer 37 can be applied to the second horizontal surface 102 of the semiconductor substrate material layer 10 and can be photolithographically patterned to form openings therethrough. The pattern of the openings in the photoresist layer 37 can include two forked comb patterns. Each forked comb pattern can include an inner comb pattern (CPI1 or CPI2) and an outer comb pattern (CPO1 or CPO2). The first forked comb pattern (CPI1, CPO1) includes a first inner comb pattern CPI1 and a first outer comb pattern CPO1. The second forked comb pattern (CPI2, CPO2) includes a second inner comb pattern CPI2 and a second outer comb pattern CPO2.

[0102] Each inner comb pattern (CPI1 or CPI2) includes a corresponding comb shaft pattern and a corresponding comb tooth pattern that may be adjacent to the corresponding comb shaft pattern. Each comb shaft pattern of the inner comb patterns (CPI1, CPI2) may extend laterally along a first horizontal direction hd1 with or without lateral undulations. Each outer comb pattern (CPO1 or CPO2) includes a corresponding comb shaft pattern and a corresponding comb tooth pattern that may be adjacent to the corresponding comb shaft pattern. Each comb shaft pattern of the outer comb patterns (CPO1, CPO2) may extend laterally along a first horizontal direction hd1 with or without lateral undulations. The comb shaft pattern within the outer comb patterns (CPO1, CPO2) may be adjacent to a comb shaft extension pattern CSEP, which extends laterally along a second horizontal direction hd2 perpendicular to the first horizontal direction hd1. Specifically, the end segment of each of the comb axis patterns within the outer comb patterns (CPO1, CPO2) can be adjacent to the end segment of the comb axis extension pattern CSEP, such that the set of the outer comb patterns (CPO1, CPO2) and the comb axis patterns within the comb axis extension pattern CSEP together form a generally rectangular shape that defines the outer boundary of the cavity to be subsequently formed in the semiconductor matrix material layer 10.

[0103] The two forked comb patterns can be configured such that the two inner comb patterns (CPI1, CPI2) are close to each other and the two outer comb patterns (CPO1, CPO2) are far apart from each other. In other words, the lateral spacing between the comb axis patterns of the two outer comb patterns (CPO1, CPO2) along the second horizontal direction hd2 is greater than the lateral spacing between the comb axis patterns of the two inner comb patterns (CPI1, CPI2).

[0104] An elongated region masked by photoresist layer 37 can be disposed between the comb axis patterns of two inner comb patterns (CPI1, CPI2), the elongated region containing the area from which the test quality block (i.e., the central quality block portion) will subsequently be patterned from the semiconductor substrate material layer 10. An opening in photoresist layer 37 can contain a test quality block barrier pattern PMBP located at the boundary of the area from which the test quality block will subsequently be formed. The comb axis patterns of the two inner comb patterns (CPI1, CPI2) can have extensions surrounding the test quality block barrier pattern PMBP to provide an etchant shrinkage structure that hinders lateral etching of portions of the semiconductor substrate material layer 10 surrounding the test quality block barrier pattern PMBP.

[0105] Each comb pattern within the inner comb patterns (CPI1, CIP2) and the outer comb patterns (CPO1, CPO2) comprises multiple comb patterns parallel to each other. Each comb pattern extends laterally away from the corresponding comb axis pattern along the common longitudinal direction of the comb patterns. Each comb pattern may be elongated in the longitudinal direction and may have a stem region having a substantially uniform width and attached to the corresponding comb axis pattern. Each comb pattern may also have a tip section having a width that gradually decreases with distance from the corresponding comb axis pattern. The common longitudinal direction of the comb patterns within the comb patterns may be at an angle between 1 degree and 10 degrees (such as 2 degrees to 8 degrees) relative to the second horizontal direction hd2 in order to optimize the capacitance change in the subsequently formed capacitor structure as the subsequently formed active structure displaces. The tip section of each comb pattern can advantageously be used to increase the capacitance change during the displacement of the subsequently formed active structure (i.e., the central mass block portion).

[0106] The comb patterns of the first inner comb pattern CPI1 and the first outer comb pattern CPO1 can be forked with respect to the parallel longitudinal direction for all of them. The forked region may include the tip segment of the first inner comb pattern CPI1 and the comb pattern of the first outer comb pattern CPO1. Similarly, the comb patterns of the second inner comb pattern CPI2 and the second outer comb pattern CPO2 can be forked with respect to the parallel longitudinal direction for all of them. The forked region may include the tip segment of the second inner comb pattern CPI2 and the comb pattern of the second outer comb pattern CPO2. The longitudinal direction of the comb patterns of the second inner comb pattern CPI2 and the second outer comb pattern CPO2 can be inclined in the opposite direction to the second horizontal direction hd2 relative to the longitudinal direction of the comb patterns of the first inner comb pattern CPI1 and the first outer comb pattern CPO1. The overall pattern of the openings in the photoresist layer 37 can have a mirror symmetry plane (MSP) extending along the first horizontal direction hd1.

[0107] In one embodiment, the region where the test mass block is subsequently formed, and the portion of the comb axis pattern of the two inner comb patterns (CPI1, CPI2) extending along the first horizontal direction hd1, may be located between a pair of longitudinal sidewalls of the first semiconductor oxide substrate 12A in a top view. While this disclosure is described using an embodiment describing an accelerometer, and the pattern of the openings in the photoresist layer 37 can be optimized for forming an accelerometer, the method of this disclosure can be used to form any microstructure containing an active structure comprising a test mass block (i.e., an active central mass block). Thus, the design of the openings in the photoresist layer 37 may or may not be symmetrical. Furthermore, while this disclosure is described using two sets of forked patterns, a single forked pattern or three or more forked patterns can be used to form a single forked comb structure or three or more forked comb structures for a microstructure, which may be a MEMS device. Generally, the test mass block can be formed within a region defined by the periphery of the first semiconductor oxide substrate 12A.

[0108] Furthermore, the pattern in the photoresist layer 37 may include a pattern of edge grooves laterally surrounding the areas of the comb tooth patterns of the first inner comb pattern CPI1 and the comb tooth patterns of the first outer comb pattern CPO1. For example, the pattern of the edge grooves may include: a pattern for a proximal edge groove laterally surrounding the area of ​​the edge groove pattern, which laterally surrounds the areas of the comb tooth patterns of the first inner comb pattern CPI1 and the comb tooth patterns of the first outer comb pattern CPO1; a pattern for a middle edge groove laterally surrounding the pattern for the proximal edge groove; a pattern for a distal edge groove laterally surrounding the pattern for the middle edge groove; and a pattern for a suspension spring edge groove, which serves to connect the corresponding pairs of patterns of the proximal edge groove pattern and the comb shaft portion.

[0109] An anisotropic etching process can be performed to transfer a pattern of openings in the photoresist layer 37 through the upper portion of the semiconductor substrate layer 10. The anisotropic etching process can be a reactive ion etching process that etches the unmasked portion of the semiconductor substrate layer 10. Therefore, the anisotropic etching process can replicate the pattern of openings in the photoresist layer in the upper portion of the semiconductor substrate layer 10. Comb trenches (31, 41, 51) can be formed through the upper portion of the semiconductor substrate layer 10. Each of the comb trenches can extend from the second horizontal surface 102 of the semiconductor substrate layer 10 toward the first horizontal surface 101 of the semiconductor substrate layer 10. In one embodiment, the comb trenches (31, 41, 51) extend vertically to a horizontal plane containing the top surface of the first semiconductor oxide substrate 12A, i.e., the horizontal plane containing the horizontal interface between the first semiconductor oxide substrate 12A and the semiconductor substrate layer 10. An anisotropic etching process may employ etching chemicals for selectively etching the semiconductor matrix material layer 10 against the first semiconductor oxide substrate 12A. For example, an anisotropic etching process may employ etching chemicals using HBr / NF3 / O2 / SF6.

[0110] Two forked comb-like grooves can be formed, each replicating a forked comb pattern. Each forked comb-like groove may include an inner comb-like groove 31 and an outer comb-like groove 41. The first forked comb-like groove includes a first inner comb-like groove 311 and a first outer comb-like groove 411 located on one side of the mirror symmetry plane (MSP). The second forked comb-like groove includes a second inner comb-like groove 312 and a second outer comb-like groove 412 located on the opposite side of the mirror symmetry plane (MSP).

[0111] Each internal comb groove 31 includes a corresponding comb groove shaft portion that replicates the comb shaft pattern and a corresponding comb groove tooth portion that replicates the comb tooth pattern and is adjacent to the corresponding comb groove shaft portion. Each comb groove shaft portion of the internal comb groove 31 may extend laterally along a first horizontal direction hd1 with or without lateral undulations. Each external comb groove 41 includes a corresponding comb groove shaft portion that replicates the comb shaft pattern and a corresponding comb groove tooth portion that replicates the comb tooth pattern and is adjacent to the corresponding comb groove shaft portion. Each comb groove shaft portion of the external comb groove 41 may extend laterally along a first horizontal direction hd1 with or without lateral undulations. The comb groove shaft portions within the external comb groove 41 may be adjacent to a comb groove extension portion 43 that extends laterally along a second horizontal direction hd2. Specifically, the end segment of each of the comb groove shaft portions within the outer comb groove 41 may be adjacent to the end segment of the comb groove extension 43, such that the collection of the outer comb groove 41 and the comb groove shaft portions within the comb groove extension 43 together forms a generally rectangular shape that defines the outer boundary of the cavity to be subsequently formed in the semiconductor matrix material layer 10.

[0112] The two finger-shaped comb grooves (31, 41) can be configured such that the two inner comb grooves (311, 312) are close to each other and the two outer comb grooves (411, 412) are far apart from each other. In other words, the lateral spacing between the comb groove axis portions of the two outer comb grooves (411, 412) along the second horizontal direction hd2 is greater than the lateral spacing between the comb groove axis portions of the two inner comb grooves (311, 312).

[0113] A first portion of the semiconductor matrix material layer 10, having a generally elongated rectangular shape, may be disposed between the comb trench axis portions of two internal comb trenches (311, 312), the first portion corresponding to the area of ​​the test mass block (i.e., the central mass block portion) to be patterned. Test mass block barrier trenches 51 may be formed below openings in the photoresist layer 37, these openings containing test mass block barrier patterns (PMBPs) located at the boundaries of the area where the test mass block will subsequently be formed. A pair of test mass block barrier trenches 51 may be laterally spaced along a first horizontal direction hd1. The comb trench axis portions of the two internal comb trenches (311, 312) may have extensions surrounding the test mass block barrier trenches 51 and may subsequently be used to form a structure constraining the lateral etching of the semiconductor matrix material layer 10 during a subsequent isotropic etching process.

[0114] Each comb-shaped groove tooth portion within the inner comb-shaped groove 31 and the outer comb-shaped groove 41 may comprise a plurality of comb-shaped groove tooth portions parallel to each other. Each comb-shaped groove tooth portion extends laterally away from the corresponding comb-shaped groove axis portion along a common longitudinal direction. Each comb-shaped groove tooth portion may be elongated in the longitudinal direction and may have a stem region having a substantially uniform width and attached to the corresponding comb-shaped groove axis portion, and may have a tip section having a width that gradually decreases with distance from the corresponding comb-shaped groove axis portion. The common longitudinal direction of the comb-shaped groove tooth portions within the comb-shaped groove tooth portion may be at an angle ranging from 1 degree to 10 degrees (e.g., from 2 degrees to 8 degrees). The tip section of each comb-shaped groove tooth portion can advantageously be used to increase capacitance changes during displacement of the subsequently formed movable structure.

[0115] The comb-shaped groove teeth of the first inner comb-shaped groove 311 and the comb-shaped groove teeth of the first outer comb-shaped groove 411 can be forked with respect to the parallel longitudinal direction for all of the comb-shaped groove teeth. The forked region may include the tip section of the first inner comb-shaped groove 311 and the comb-shaped groove teeth of the first outer comb-shaped groove 411. Similarly, the comb-shaped groove teeth of the second inner comb-shaped groove 312 and the comb-shaped groove teeth of the second outer comb-shaped groove 412 can be forked with respect to the parallel longitudinal direction for all of the comb-shaped groove teeth. The forked region may include the tip section of the second inner comb-shaped groove 312 and the comb-shaped groove teeth of the second outer comb-shaped groove 412. The longitudinal direction of the comb-shaped groove teeth portion of the second inner comb-shaped groove 312 and the comb-shaped groove teeth portion of the second outer comb-shaped groove 412 may be inclined in the opposite direction to the second horizontal direction hd2 relative to the longitudinal direction of the comb-shaped groove teeth portion of the first inner comb-shaped groove 311 and the comb-shaped groove teeth portion of the first outer comb-shaped groove 411. The overall pattern of the comb-shaped grooves (31, 41, 51) may have a mirror symmetry plane (MSP) extending along the first horizontal direction hd1.

[0116] In one embodiment, the area where the inspection quality block is subsequently formed and the portion of the comb groove axis of the two internal comb grooves (311, 312) extending along the first horizontal direction hd1 may be located between a pair of longitudinal sidewalls of the first semiconductor oxide substrate 12A in a top view. The photoresist layer 37 may then be removed, for example, by ashing.

[0117] The edge grooves (81, 91, 96, 86) may laterally surround the areas of the inner comb groove 31 and the outer comb groove 41. For example, the edge grooves (81, 91, 96, 86) may include: a proximal edge groove 81, laterally surrounding the inner comb groove 31 and the outer comb groove 41; an intermediate edge groove 91, laterally surrounding the proximal edge groove 81; a distal edge groove 96, laterally surrounding the intermediate edge groove 91; and a suspension spring edge groove 86, connecting the section of the proximal edge groove 81 and the corresponding pair of comb groove axis portions of the two outer comb grooves (411, 412).

[0118] refer to Figure 7A , Figure 7B , Figures 8A to 8H and Figures 9A to 9H At least one trench filling material may be deposited in each trench of the semiconductor matrix material layer 10. Generally, at least one trench filling material may be deposited in a first trench (such as an inner comb trench 31) and a second trench (such as an outer comb trench 41). According to the present disclosure, at least one trench filling material includes at least one metallic material. In one embodiment, the metallic material may be selected from elemental metals (such as transition metals), intermetallic alloys of at least two elemental metals, metal-semiconductor alloys, and conductive metal nitride materials (such as conductive metal nitride materials). In one embodiment, at least one trench filling material may comprise a single metallic material or may comprise multiple metallic materials deposited in multiple deposition processes.

[0119] Generally, at least one trench filler material can be deposited in the comb trenches (31, 41, 51) and the edge trenches (81, 91, 96, 86), and deposited above the second horizontal surface 102 of the semiconductor matrix material layer 10. The at least one trench filler material may additionally comprise at least one semiconductor material and / or at least one dielectric material. In one embodiment, each of the at least one trench filler material can be deposited by a corresponding conformal deposition process, such as chemical vapor deposition. In one embodiment, the total thickness of the at least one trench filler material can be greater than half the maximum width of each trench in the semiconductor matrix material layer 10.

[0120] Excess portions of at least one trench filler material can be partially or completely removed from above the second horizontal surface 102 of the semiconductor matrix material layer 10 using a planarization process. The planarization process can utilize chemical mechanical planarization (CMP) and / or trench etching processes. Each remaining portion of at least one trench filler material in a corresponding trench includes a comb structure (30, 40). Specifically, the comb structure (30, 40) includes a movable comb structure 30 and a stationary comb structure 40. A first interdigitated comb structure (301, 401) including a first movable comb structure 301 and a first stationary comb structure 401 can be formed on one side of a mirror symmetry plane (MSP), while a second interdigitated comb structure (302, 402) including a second movable comb structure 302 and a second stationary comb structure 402 can be formed on the opposite side of the mirror symmetry plane MSP. A barrier structure 50 can be formed in each inspection quality block barrier trench 51.

[0121] In one embodiment, at least one trench filling material may comprise a metallic material and a semiconductor material. Figure 8A and Figure 9A The illustrations show the first configurations of the movable comb fingers of the movable comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In the first configuration, each movable comb finger may include a combination of a metal material portion 32 and a semiconductor material portion 34 in contact with the metal material portion 32, and each stationary comb finger may include a metal material portion 42 and a semiconductor material portion 44 in contact with the metal material portion 42.

[0122] In one embodiment, at least one trench filling material may comprise a variety of metallic and semiconductor materials. Figure 8B and Figure 9B The illustrations show a second configuration of the active comb fingers of the active comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In the second configuration, each active comb finger may include a combination of a first metal material portion 32, a semiconductor material portion 34 in contact with the first metal material portion 32, and a second metal material portion 36 in contact with the semiconductor material portion 34. Each stationary comb finger may include a combination of a first metal material portion 42, a semiconductor material portion 44 in contact with the first metal material portion 42, and a second metal material portion 46 in contact with the semiconductor material portion 44. In one embodiment, each semiconductor material portion (34, 44) includes a doped polysilicon-containing material having p-type or n-type doping. For example, each semiconductor material portion (34, 44) may include doped polysilicon.

[0123] In one embodiment, at least one trench filling material may comprise a variety of metallic materials and a variety of semiconductor materials. Figure 8C and Figure 9C The diagrams illustrate a third configuration of the active comb fingers of the active comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In this third configuration, each active comb finger may comprise a combination of a first metal material portion 32, a first semiconductor material portion 34 in contact with the first metal material portion 32, a second metal material portion 36 in contact with the first semiconductor material portion 34, and a second semiconductor material portion 38 in contact with the second metal material portion 36. Each stationary comb finger may comprise a combination of a first metal material portion 42, a first semiconductor material portion 44 in contact with the first metal material portion 42, a second metal material portion 46 in contact with the first semiconductor material portion 44, and a second semiconductor material portion 48 in contact with the second metal material portion 46. In one embodiment, each semiconductor material portion (34, 44, 38, 48) comprises a doped polysilicon-containing material having p-type or n-type doping. For example, each semiconductor material portion (34, 44, 38, 48) may comprise doped polysilicon.

[0124] In some embodiments, dielectric pads (33, 43) Figures 8D to 8F , Figure 8H , Figure 9D up to Figure 9F and Figure 9H (As illustrated in the figure) The semiconductor substrate material layer 10 can be conformally formed on the solid exposed surface of the comb trenches (31, 41, 51), in the edge trenches (81, 91, 96, 86), and above the second horizontal surface 102 of the semiconductor substrate material layer 10. In one embodiment, the dielectric pads (33, 43) can be formed by an oxidation process that transforms a portion of the solid exposed surface of the semiconductor substrate material layer 10 into a semiconductor oxide pad, such as a silicon oxide pad. Alternatively, the dielectric pads (33, 43) can be formed by conformally depositing a dielectric material such as silicon oxide, silicon nitride, or dielectric metal oxides (such as aluminum oxide and / or hafnium oxide). The thickness of the dielectric pads (33, 43) can be in the range of 4 nm to 100 nm, such as in the range of 6 nm to 20 nm. In general, the thickness of the dielectric pads (33, 43) can be optimized to maximize the capacitive coupling between the comb structures that will subsequently be formed, and minimize the leakage current through the dielectric pad layer.

[0125] In one embodiment, at least one trench filling material may comprise dielectric pads (33, 43), metallic materials, and semiconductor materials. Figure 8D and Figure 9DThe illustrations show a fourth configuration of the movable comb fingers of the movable comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In this fourth configuration, each movable comb finger may include a combination of a dielectric pad 33, a metal material portion 32, and a semiconductor material portion 34 in contact with the metal material portion 32. Each stationary comb finger may include a combination of a dielectric pad 43, a metal material portion 42, and a semiconductor material portion 44 in contact with the metal material portion 42.

[0126] In one embodiment, at least one trench filling material may comprise a dielectric liner (33 or 42), various metallic materials, and semiconductor materials. Figure 8E and Figure 9E The illustrations show a fifth configuration of the active comb fingers of the active comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In this fifth configuration, each active comb finger may include a combination of a dielectric pad 33, a first metal material portion 32, a semiconductor material portion 34 in contact with the first metal material portion 32, and a second metal material portion 36 in contact with the semiconductor material portion 34. Each stationary comb finger may include a combination of a dielectric pad 43, a first metal material portion 42, a semiconductor material portion 44 in contact with the first metal material portion 42, and a second metal material portion 46 in contact with the semiconductor material portion 44. In one embodiment, each semiconductor material portion (34, 44) comprises a doped polysilicon-containing material having p-type or n-type doping. For example, each semiconductor material portion (34, 44) may comprise doped polysilicon.

[0127] In one embodiment, at least one trench filling material may comprise a dielectric liner (33 or 42), various metallic materials, and various semiconductor materials. Figure 8F and Figure 9F The illustrations show a sixth configuration of the active comb fingers of the active comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In this sixth configuration, each active comb finger may include a combination of a dielectric pad 33, a first metal material portion 32, a first semiconductor material portion 34 in contact with the first metal material portion 32, a second metal material portion 36 in contact with the first semiconductor material portion 34, and a second semiconductor material portion 38 in contact with the second metal material portion 36. Each stationary comb finger may include a combination of a dielectric pad 43, a first metal material portion 42, a first semiconductor material portion 44 in contact with the first metal material portion 42, a second metal material portion 46 in contact with the first semiconductor material portion 44, and a second semiconductor material portion 48 in contact with the second metal material portion 46. In one embodiment, each semiconductor material portion (34, 44, 38, 48) comprises a doped polysilicon-containing material having p-type or n-type doping. For example, each semiconductor material portion (34, 44, 38, 48) may comprise doped polysilicon.

[0128] In one embodiment, at least one trench filling material may be composed of a metallic material. Figure 8G and Figure 9G The illustrations show the seventh configuration of the movable comb fingers of the movable comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In the seventh configuration, each movable comb finger can be composed of a metal material portion 32. Each stationary comb finger can be composed of a metal material portion 42.

[0129] In one embodiment, at least one trench filling material may comprise a combination of a dielectric liner (33 or 43) and a metallic material. Figure 8H and Figure 9H The diagrams illustrate the eighth configuration of the movable comb fingers of the movable comb structure 30 and the stationary comb fingers of the stationary comb structure 40. In the eighth configuration, each movable comb finger may include a combination of a dielectric pad 33 and a metal material portion 32. Each stationary comb finger may include a combination of a dielectric pad 43 and a metal material portion 42.

[0130] Generally, the metallic material portions (32, 36) in the movable comb structure 30 can extend continuously through each of the movable comb fingers as a continuous structure. Similarly, the metallic material portions (42, 46) in the stationary comb structure 40 can extend continuously through each of the stationary comb fingers as a continuous structure. In one embodiment, the metallic material portions (32, 36) in the movable comb structure 30 can include areas of uniform width in each of the movable comb fingers as a continuous structure. Similarly, the metallic material portions (42, 46) in the stationary comb structure 40 can include areas of uniform width in each of the stationary comb fingers as a continuous structure. In one embodiment, each metallic material portion (32, 36) in the movable comb structure 30 can have a metallic composition, and the metallic material portions (42, 46) in the stationary comb structure 40 can include additional metallic material portions having the same material composition as the metallic material portions (32, 36) in the movable comb structure 30.

[0131] Generally speaking, it can form Figure 7A , Figure 7B , Figures 8D to 8F , Figure 8H , Figure 9D up to Figure 9F and Figure 9HThe various dielectric pads (33, 43, 52, 82, 92, 87, 97) shown in the figure. The dielectric pads (33, 43, 52, 82, 92, 87, 97) include an inner dielectric pad 33 formed in a corresponding one of the inner comb-shaped trenches 31, an outer dielectric pad 43 formed in a corresponding one of the outer comb-shaped trenches 41, a barrier dielectric pad 52 formed in a corresponding one of the inspection quality block barrier trenches 51, and an edge trench dielectric pad (82, 92, 87, 97). A barrier conductive filler portion 54 may be formed in a corresponding one of the inspection quality block barrier trenches 51, and an edge trench filler portion (84, 94, 89, 99) may be formed in a corresponding one of the edge trenches (81, 91, 86, 96). A barrier structure 50, comprising a barrier dielectric pad 52 and a barrier conductive filler portion 54, can be formed in each inspection quality block barrier trench 51. The edge trench dielectric pads (82, 92, 87, 97) can include: an inner dielectric pad 82, formed in the adjacent edge trench 81; an intermediate dielectric pad 92, formed in the intermediate edge trench 91; an outer dielectric pad 97, formed in the distal edge trench 96; and a suspension spring dielectric pad 87, formed in the suspension spring edge trench 86.

[0132] The combination of the inner dielectric pad 82 and the adjacent filler material portion 84 constitutes the adjacent wall structure 80. The combination of the intermediate dielectric pad 92 and the intermediate filler material portion 94 constitutes the intermediate wall structure 90. The combination of the outer dielectric pad 97 and the distal filler material portion 99 constitutes the distal wall structure 95. Each combination of the suspension spring dielectric pad 87 and the suspension spring filler material portion 89 constitutes the suspension wall structure 85.

[0133] Generally, each of the comb-like structures (30, 40) may include a corresponding dielectric pad (33 or 43) and a corresponding conductive filler portion (32, 34, 36, 38, 42, 44, 46, 48). Each of the comb-like structures (30, 40) extends from the second horizontal surface 102 of the semiconductor substrate material layer 10 toward the first horizontal surface 101 of the semiconductor substrate material layer 10 at the interface with the second semiconductor oxide substrate 12B. Each dielectric pad (33, 43) may be a patterned portion of the dielectric pad layer, and each conductive filler portion (32, 34, 36, 38, 42, 44, 46, 48) may be the remaining portion of the corresponding conductive filler material. In one embodiment, the comb structures (30, 40) include: a pair of movable comb structures (301, 302) laterally spaced apart by a first portion of the semiconductor matrix material layer 10; and a pair of stationary comb structures (401, 402) interdigitated with the pair of movable comb structures (301, 302). The comb shaft portions of the stationary comb structures (401, 402) extend along a first horizontal direction hd1 and subsequently along a second horizontal direction hd2 to abut each other, thereby defining a substantially rectangular region completely laterally surrounded by the combined comb shaft portions of the stationary comb structures (401, 402). In other words, the comb shaft portions of the stationary comb structures (401, 402) can form a framework laterally surrounding all the tooth portions of the stationary comb structures (401, 402) and the entire movable comb structure (301, 302).

[0134] Two finger-shaped comb structures (30, 40) can be formed, each having a horizontal cross-sectional shape that replicates the pattern in one of the two finger-shaped comb patterns. Each finger-shaped comb structure (30, 40) may include a movable comb structure 30 and a stationary comb structure 40. The first finger-shaped comb structure includes a first movable comb structure 301 and a first stationary comb structure 401 located on one side of the mirror symmetry plane (MSP). The second finger-shaped comb structure includes a second movable comb structure 302 and a second stationary comb structure 402 located on the opposite side of the mirror symmetry plane (MSP).

[0135] Each active comb structure 30 includes a corresponding comb structure shaft portion that replicates the comb shaft pattern and a corresponding comb structure tooth portion that replicates the comb tooth pattern and is adjacent to the corresponding comb structure shaft portion. Each comb structure shaft portion of the active comb structure 30 may extend laterally along a first horizontal direction hd1 with or without lateral undulations. Each stationary comb structure 40 includes a corresponding comb structure shaft portion that replicates the comb shaft pattern and a corresponding comb structure tooth portion that replicates the comb tooth pattern and is adjacent to the corresponding comb structure shaft portion. Each comb structure shaft portion of the stationary comb structure 40 may extend laterally along a first horizontal direction hd1 with or without lateral undulations. The comb structure shaft portion within the stationary comb structure 40 may be adjacent to a comb structure extension portion 46 that extends laterally along a second horizontal direction hd2. Specifically, the end segment of each of the comb structure shaft portions within the stationary comb structure 40 may be adjacent to the end segment of the comb structure extension 46, such that the collection of the comb structure shaft portions within the stationary comb structure 40 and the comb structure extension 46 together forms a generally rectangular shape that defines the outer boundary of the cavity to be subsequently formed in the semiconductor matrix material layer 10.

[0136] The two finger-shaped comb structures (30, 40) can be configured such that the two movable comb structures (301, 302) are close to each other and the two stationary comb structures (401, 402) are far apart from each other. In other words, the lateral spacing between the comb structure axis portions of the two stationary comb structures (401, 402) along the second horizontal direction hd2 is greater than the lateral spacing between the comb structure axis portions of the two movable comb structures (301, 302).

[0137] A first portion of the semiconductor matrix material layer 10, having a generally elongated rectangular shape, may be disposed between the comb-shaped axis portions of two movable comb structures (301, 302), the first portion corresponding to the area of ​​the inspection quality block (i.e., the central quality block portion) to be patterned. A barrier structure 50 may be formed in the inspection quality block barrier trench 51. A pair of barrier structures 50 may be laterally spaced along a first horizontal direction hd1. The comb-shaped axis portions of the two movable comb structures (301, 302) may have extensions surrounding the barrier structure 52, and are subsequently used to form a structure constraining the lateral etching of the semiconductor matrix material layer 10 during subsequent isotropic etching processes.

[0138] Each comb-shaped tooth portion within the movable comb structure 30 and the stationary comb structure 40 comprises a plurality of comb-shaped tooth portions that can be parallel to each other. Each comb-shaped tooth portion extends laterally away from the corresponding comb-shaped axis portion along a common longitudinal direction. Each comb-shaped tooth portion can be elongated in the longitudinal direction and can have a stem region having a substantially uniform width and attached to the corresponding comb-shaped axis portion, and can have a tip section having a width that gradually decreases with distance from the corresponding comb-shaped axis portion. The common longitudinal direction of the comb-shaped tooth portions within the comb-shaped tooth portion can be at an angle ranging from 1 degree to 10 degrees (e.g., from 2 degrees to 8 degrees). The tip section of each comb-shaped tooth portion can advantageously be used to increase capacitance changes during the subsequent displacement of the movable structure.

[0139] The comb-shaped teeth of the first movable comb structure 301 and the comb-shaped teeth of the first stationary comb structure 401 can be forked in the parallel longitudinal direction for all of the comb-shaped teeth. The forked region may include the tip section of the first movable comb structure 301 and the comb-shaped teeth of the first stationary comb structure 401. Similarly, the comb-shaped teeth of the second movable comb structure 302 and the comb-shaped teeth of the second stationary comb structure 402 can be forked in the parallel longitudinal direction for all of the comb-shaped teeth. The forked region may include the tip section of the second movable comb structure 302 and the comb-shaped teeth of the second stationary comb structure 402. The longitudinal direction of the comb teeth of the second movable comb structure 302 and the comb teeth of the second stationary comb structure 402 may be inclined in the opposite direction to the second horizontal direction hd2 relative to the longitudinal direction of the comb teeth of the first movable comb structure 301 and the comb teeth of the first stationary comb structure 401. The overall pattern of the comb structures (30, 40) and the barrier structure 50 may have a mirror symmetry plane (MSP) extending along the first horizontal direction hd1.

[0140] refer to Figure 10A and Figure 10BThe metallic material portions (110, 120, 130) can be formed over the second horizontal surface 102 of the semiconductor matrix material layer 10 and the comb-like structures (30, 40). For example, a patterned deposition mask (not shown), such as a patterned photoresist layer, can be formed over the exemplary structure, and at least one metallic material can be deposited by physical vapor deposition. The at least one metallic material can comprise, for example, a metal pad material (such as TiN, TaN, or WN) and an under-bump metallurgical material, such as Ni, Cr, Cu, and their stacks. The thickness of the at least one metallic material can be in the range of 100 nm to 2,000 nm, but smaller and larger thicknesses can also be used. For example, the patterned deposition mask and portions of the at least one metallic material covering the patterned deposition mask can be removed by a lift-off process.

[0141] The remaining portion of at least one metallic material deposited on the movable comb structure 30 includes a movable metal plate 110. The remaining portion of at least one metallic material deposited on the stationary comb structure 40 includes a stationary metal plate 120. The remaining portion of at least one metallic material deposited on the semiconductor matrix material layer 10 includes a spring structure 130, which may include an opening between an inner frame and an outer frame of the spring structure 130. The spring structure 130 may have a suitable pattern to apply a bias voltage to opposite portions of the stationary comb structure 40.

[0142] refer to Figure 11A and Figure 11B The etch mask material layer 67 can be applied over various metal material portions (110, 120, 130) and can be photolithographically patterned to form openings through it. The etch mask material layer 67 can contain a photoresist material or a hard mask material, such as silicon nitride, silicon oxide, or dielectric metal oxide. The etch mask material layer 67 can be directly patterned (where the etch mask material layer 67 contains a photoresist material), or it can be patterned by applying and patterning a photoresist layer over it and transferring the pattern in the photoresist layer to the etch mask material layer using an anisotropic etching process.

[0143] The pattern of the openings in the patterned etch mask layer 67 can be selectively chosen, such that a subset of the openings in the patterned etch mask layer 67 is formed within the boundary defined by the comb shaft portion and the comb extension portion 46 of the stationary comb structure 40. Furthermore, the pattern of the openings in the patterned etch mask layer 67 does not overlap with the comb structures (30, 40), the comb extension portion 46, the barrier structure 50, or a portion of the semiconductor matrix material layer 10 located between the intermediate wall structure 90 and the distal wall structure 95. The openings in the patterned etch mask layer 67 are located in areas where no metal material portions (110, 120, 130) are present. A subset of the openings in the patterned etch mask layer 67 can cover the gap region between adjacent comb tooth pairs. A subset of the openings in the patterned etch mask layer 67 can be formed between the barrier structure 50 and the comb extension portion 46. The openings in the patterned etch mask layer 67 are not present within the first portion of the semiconductor matrix material layer 10, which is located between a pair of comb structure axis portions and their lateral extensions of the active comb structure 30, and between a pair of barrier structures 50. A subset of the openings in the patterned etch mask layer 67 may be formed between adjacent wall structure structures 80 and comb structure extensions 46.

[0144] A portion of the semiconductor matrix material layer 10 can be removed around the trenches (such as the first trench and the second trench) forming the comb-like structures (30, 40). In one embodiment, at least one portion of the trench-filling material in the first trench includes a movable comb-like structure 30, and at least one portion of the trench-filling material in the second trench includes a stationary comb-like structure 40. Generally, the movable comb-like structure 30 and the stationary comb-like structure 40 can be used to generate an electrical output signal based on the capacitance change between the movable comb-like structure 30 and the stationary comb-like structure 40 after the semiconductor matrix material layer 10 is removed.

[0145] Generally, after depositing at least one trench filling material in the first trench and the second trench, the areas of the first trench and the second trench can be masked by patterned etching mask layer 67.

[0146] A combination of anisotropic and isotropic etching processes, or an isotropic etching process alone, can be used to etch the portions of the semiconductor substrate material layer 10 that are not masked by the patterned etch mask layer 67. In one embodiment, an anisotropic etching process can be formed to etch through the unmasked portions of the semiconductor substrate material layer 10. Deep trenches can be formed below openings in the patterned etch mask layer 67 to a depth of the first semiconductor oxide substrate 12A.

[0147] Subsequently, an isotropic etching process using an isotropic etchant can be performed to selectively etch the semiconductor material of the semiconductor matrix material layer 10 against the dielectric material of the first and second semiconductor oxide substrates (12A, 12B) and dielectric pads (33, 43, 52). A portion of the semiconductor matrix material layer 10 can be removed by the isotropic etching process. The removed portion of the semiconductor matrix material layer 10 includes the portion located within the lateral boundary defined by the comb structure axis portion within the stationary comb structure 40, the comb structure extension portion 46, and the inner wall structure 80, and outside the comb structure axis portion of the active comb structure 30. The removed portion of the semiconductor matrix material layer 10 is referred to herein as the second portion of the semiconductor matrix material layer 10. In addition, the portion of the semiconductor matrix material layer 10 located between the intermediate wall structure 90 and the distal wall structure 95 is removed. The unetched portion of the semiconductor matrix material layer 10 retained after the isotropic etching process and located outside the distal wall structure 95 is referred to herein as the semiconductor matrix layer 10M. The unetched portion of the semiconductor matrix material layer 10, which is retained after the isotropic etching process and located between the adjacent wall structure 80 and the intermediate wall structure 85, is referred to herein as the semiconductor frame 10F.

[0148] The isotropic etching process can use a wet etching process that selectively etches the semiconductor material of the semiconductor matrix material layer 10 against the materials of the first and second semiconductor oxide substrates (12A, 12B) and dielectric pads (33, 43, 52). In one embodiment, the wet etching process can use hot trimethyl-2-hydroxyethyl ammonium hydroxide (“thermal TMY”) or tetramethylammonium hydroxide (TMAH). The duration of the isotropic etching process can be selected such that the etching front of the isotropic etching process reaches the entire area of ​​the top surface portion of the second semiconductor oxide substrate 12B within the region defined by the combination of the comb structure shaft portion, the comb structure extension portion 46, and the adjacent wall structure 80 within the stationary comb structure 40. The comb structure extension portion 46 is attached to the semiconductor frame 10F via the spring wall structure 85 and the inner wall structure 80.

[0149] The active structure includes an active comb structure 30, a first portion of a semiconductor substrate material layer 10 located between the active comb structures 30 and remaining unetched after an isotropic etching process, and a pair of barrier structures 50 attached to the first portion of the semiconductor substrate material layer 10. This remaining unetched portion is detachable from the remaining unetched portion of the semiconductor substrate material layer 10 (referred to herein as the third portion), which is retained outside the combination of the comb structure axis portion, the comb structure extension portion 46, and the adjacent wall structure 80 within the stationary comb structure 40. In one embodiment, the peripheral region of the first portion of the semiconductor substrate material layer 10 may be incidentally etched by the isotropic etchant as the isotropic etchant flows through the meandering channel defined by the extension of the comb structure axis portion of the active comb structure 30 and the barrier structures 50.

[0150] The first portion of the semiconductor matrix material layer 10 includes a test mass block of an active structure, referred herein as the central mass block portion 10A. The third portion of the semiconductor matrix material layer 10 is referred herein as the semiconductor matrix layer 10M. First and second semiconductor oxide substrates (12A, 12B) and dielectric pads (33, 43, 52) serve as etch barrier structures defining the extent of the cavity 61 formed after the removal of the second portion of the semiconductor matrix material layer 10. The comb shaft portion within the stationary comb structure 40, the comb extension portion 46, and the inner sidewalls of the adjacent wall structure 80 can serve as the outer lateral boundaries of the cavity 61. The sidewalls of the comb shaft portion of the active comb structure 30 can serve as the inner lateral boundaries of the cavity 61, which surround the first portion of the semiconductor matrix material layer 10 that has not been etched by the isotropic etching process.

[0151] The volume of the recessed cavity 13 can be incorporated into the cavity 61. In embodiments where the cap substrate 20 comprises a semiconductor material such as silicon, the surface of the cap substrate 20 not covered by the second semiconductor oxide substrate 12B can be isotropically recessed to form a gap, which is added to the cavity 61. The gap can have an undercut below the periphery of the second semiconductor oxide substrate 12B. An isotropic etchant can laterally etch portions of the semiconductor matrix material layer 10 that lie beneath the boundary formed by the comb structure axis portion within the stationary comb structure 40, the comb structure extension portion 46, and the adjacent wall structure 80, as well as the undercut portions of the semiconductor matrix material layer 10 located outside the boundary.

[0152] In alternative embodiments, the anisotropic etching process can be omitted, and the isotropic etching process can be extended to etch through a second portion of the semiconductor matrix material layer 10 to form a cavity. In these embodiments, the duration of the isotropic etching process can be extended to ensure that the etch front of the isotropic etching process reaches the entire area of ​​the portion of the top surface of the second semiconductor oxide substrate 12B located in the region, which is defined by the combination of the comb shaft portion within the stationary comb structure 40, the comb extension portion 46, and the adjacent wall structure 80.

[0153] Generally, the isotropic etchant in an isotropic etching process can be applied via openings in a patterned etch mask layer 67. The isotropic etchant selectively etches the semiconductor material of the semiconductor matrix layer 10 against the material of the semiconductor oxide substrates (12A, 12B) and against the material of the comb structures (30, 40) that contact the semiconductor matrix layer 10 (which may be the material of the dielectric pads (33, 43)). The isotropic etching process can be used to selectively remove a second portion of the semiconductor matrix layer 10 laterally surrounding a first portion of the semiconductor matrix layer 10 against the comb structures (30, 40). The first portion of the semiconductor matrix layer 10 can be protected from the etchant of the isotropic etching process and covered by the comb structures 30 by the first semiconductor oxide substrate 12A, the pair of movable comb structures 30, and the patterned etch mask layer 67 located on the second horizontal surface 102 of the semiconductor matrix layer 10.

[0154] During the isotropic etching process, a portion of the patterned etch mask layer 67 covering the first portion of the semiconductor matrix material layer 10 protects the front surface of the first portion of the semiconductor matrix material layer 10. During the isotropic etching process, the first semiconductor oxide substrate 12A protects the back side of the first portion of the semiconductor matrix material layer 10. Therefore, the central mass block portion 10A of the first portion of the semiconductor matrix material layer 10 after the isotropic etching process can have a uniform thickness between the interface between the first semiconductor oxide substrate 12A and the patterned etch mask layer 67. In one embodiment, the central mass block portion 10A can have a uniform thickness throughout the entire region laterally surrounded by the comb structure axis portion of the movable comb structure 30 and the barrier structure 50.

[0155] Cavity 61 can be formed by removing a second portion of semiconductor substrate material layer 10. Semiconductor substrate layer 10M, containing an unetched third portion of semiconductor substrate material layer 10, laterally surrounds cavity 61. Movable structures (10A, 30, 50) comprising a first portion of semiconductor substrate material layer 10 and a pair of movable comb structures 30 can be detached from semiconductor substrate layer 10M by an isotropic etching process.

[0156] The movable comb structure 30 can be an element of the movable structure (10A, 30, 50) and is referred to hereinafter as the movable comb structure 30. The movable comb structure 30 includes a first movable comb structure 301 and a second movable comb structure 302. The comb structure teeth portion of the movable comb structure 30 includes the movable comb fingers of the movable structure (10A, 30, 50).

[0157] The stationary comb structure 40 can be a stationary element, and is thus referred to hereinafter as the stationary comb structure 40. The stationary comb structure 40 includes a first stationary comb structure 401 and a second stationary comb structure 402. The comb structure tooth portion of the stationary comb structure 40 includes stationary comb fingers. In one embodiment, the movable comb structure 30 includes a comb shaft portion and movable comb fingers projecting laterally from the comb shaft portion, and the stationary comb structure 40 includes stationary comb fingers that intersect with the movable comb fingers.

[0158] refer to Figure 13A and Figure 13B The patterned etch mask layer 67 can be removed, for example, by ashing. Metal material portions (110, 120, 130) are located on the top surfaces of the movable structures (10A, 30, 50), the stationary comb structure 40, the semiconductor frame 10F, and the semiconductor matrix layer 10M. The metal material portions (110, 120, 130) include: a movable metal plate 110 formed on the movable structures (10A, 30, 50); a stationary metal plate 120 formed on the stationary comb structure 40; and a spring structure 130 formed on the semiconductor frame 10F and the semiconductor matrix layer 10M, and above the gap between the semiconductor frame 10F and the semiconductor matrix layer 10M. The spring structure 130 includes an opening above the area of ​​the gap to provide elasticity.

[0159] refer to Figure 14 Each accelerometer 100 above the cap substrate 20 can be individualized, for example, by vacuum cutting. The cap substrate 20 may or may not be removed. In one embodiment, the cap substrate 20 can be removed, for example, by removing a semiconductor oxide substrate (12A, 12B). For example, a wet etching using hydrofluoric acid can be performed to remove the semiconductor oxide substrate (12A, 12B). Each accelerometer 100 can be electrically connected to controller circuitry or a control unit using wiring, which can be attached to the spring structure 130 or the stationary metal plate 120. The control circuitry or control unit can be used to measure acceleration based on changes in capacitance of a capacitor structure within the accelerometer 100.

[0160] Although this disclosure is described using an accelerometer 100 as an example, the methods disclosed herein can be used to form any micro-electromechanical system (MEMS) device comprising a movable comb structure 30 and a stationary comb structure, wherein the movable comb structure 30 moves relative to the stationary comb structure and generates electrical signals.

[0161] Common Reference Figures 1A to 14 Furthermore, according to various embodiments disclosed herein, a micro-electromechanical system (MEMS) device is provided, comprising: a movable comb structure 30 located in a cavity within a housing and including a comb shaft portion and movable comb fingers projecting laterally from the comb shaft portion, wherein the movable comb structure includes metallic material portions (32, 36); and a stationary structure (such as a stationary comb structure 40) fixed to the housing, wherein the movable comb structure 30 and the stationary structure are used to generate an electrical output signal based on lateral movement of the movable comb structure 30 relative to the stationary structure.

[0162] In one embodiment, the active comb structure 30 includes a semiconductor material portion 34 in contact with the metallic material portion (32 or 36). In one embodiment, the semiconductor material portion 34 includes a doped polysilicon-containing material having p-type or n-type doping.

[0163] In one embodiment, the movable comb structure 30 includes a dielectric pad 33 in contact with at least one metallic portion 32. In one embodiment, the surface of the dielectric pad 33 is substantially exposed to the cavity. In one embodiment, the metallic portions (32, 36) are laterally surrounded by the dielectric pad 33; and the dielectric pad 33 comprises a material selected from silicon oxide, silicon nitride, and dielectric metal oxides.

[0164] In one embodiment, the surface of the metal material portion 32 is solidly exposed to the cavity. In one embodiment, the metal material portions (32, 36) comprise a material selected from elemental metals, intermetallic alloys, metal-semiconductor alloys, and conductive metal nitride materials. In one embodiment, the metal material portions (32, 36) extend continuously as a continuous structure through each of the movable comb fingers. In one embodiment, the metal material portions (32, 36) may be included within each of the movable comb fingers a region of uniform width.

[0165] In one embodiment, the stationary structure includes a stationary comb structure comprising stationary comb fingers that intersect with the movable comb fingers. In one embodiment, the movable comb fingers include additional metallic material portions (42, 46) having the same material composition as the metallic material portions (32, 36).

[0166] According to the present disclosure, a micro-electromechanical system (MEMS) device is provided, comprising: a movable comb structure 30 located in a cavity within a housing and including a comb shaft portion and a plurality of movable comb fingers projecting laterally from the comb shaft portion, wherein the movable comb structure 30 includes a first metallic material portion (32, 36); and a stationary structure (such as a stationary comb structure 40), fixed to the housing and including a second metallic material portion (42, 46) having the same material composition as the first metallic material portion (32, 36), wherein the movable comb structure 30 and the stationary structure are used to generate an electrical output signal based on a capacitance change between the movable comb structure and the stationary structure.

[0167] In one embodiment, the MEMS device includes an accelerometer. In one embodiment, the active comb structure includes a first semiconductor material portion (34, 38); and the stationary structure includes a second semiconductor material portion (44, 48) having the same material composition as the first semiconductor material portion (34, 38).

[0168] In one embodiment, a first metallic portion (32, 36) extends continuously through each of the active comb fingers; a stationary structure includes stationary comb fingers that intersect with the active comb fingers; and a second metallic portion (42, 46) extends continuously through each of the stationary comb fingers.

[0169] refer to Figure 15 Flowchart 1500 illustrates a set of processing steps that can be executed to form a MEMS device according to embodiments of the present disclosure. Refer to step 1510 and... Figure 6A and Figure 6B A first trench (such as an internal comb trench 31) and a second trench (such as an external comb trench 41) can be formed in the semiconductor matrix material layer 10. Refer to step 1520 and... Figure 7A , Figure 7B , Figures 8A to 8H , Figures 9A to 9H At least one trench filling material (33, 32, 34, 36, 38, 43, 42, 44, 46, 48) may be deposited in the first and second trenches. The at least one trench filling material includes the metallic material forming the metallic portion (32, 36, 42, 46). Refer to step 1530 and... Figures 10A to 13BA portion of the semiconductor matrix material layer 10 can be removed around the first and second trenches. A portion of at least one trench-filling material (33, 32, 34, 36, 38, 43, 42, 44, 46, 48) in the first trench includes a movable comb structure 30, and a portion of at least one trench-filling material (33, 32, 34, 36, 38, 43, 42, 44, 46, 48) in the second trench includes a stationary structure (such as a stationary comb structure 40). The movable comb structure 30 and the stationary structure are used to generate an electrical output signal based on a capacitance change between the movable comb structure and the stationary structure, for example, as in an accelerometer.

[0170] Various embodiments disclosed herein provide a MEMS device using a metallic material in at least one movable comb structure 30. Compared to semiconductor material portions having the same geometry, metallic materials offer greater mechanical strength and fracture resistance through increased ductility, and thus can increase the reliability of the MEMS device.

[0171] According to one embodiment of this application, a microelectromechanical system (MEMS) device includes a movable comb-like structure located in a cavity within a housing and comprising: a comb shaft portion; and a plurality of movable comb fingers projecting laterally from the comb shaft portion, wherein the movable comb-like structure includes a metallic portion; and a stationary structure fixed to the housing, wherein the movable comb-like structure and the stationary structure are configured to generate an electrical output signal based on lateral movement of the movable comb-like structure relative to the stationary structure. In some embodiments, the movable comb-like structure includes a semiconductor material portion in contact with the metallic portion. In some embodiments, the semiconductor material portion includes a doped polysilicon-containing material having a p-type or n-type doping. In some embodiments, the movable comb-like structure includes a dielectric pad in contact with the metallic portion. In some embodiments, a plurality of surfaces of the dielectric pad are substantially exposed in the cavity. In some embodiments, the metallic portion is laterally surrounded by the dielectric pad; and the dielectric pad includes a material selected from silicon oxide, silicon nitride, and a dielectric metal oxide. In some embodiments, a plurality of surfaces of the metallic portion are substantially exposed in the cavity. In some embodiments, the metallic material portion comprises a material selected from an elemental metal, an intermetallic alloy, a metal-semiconductor alloy, and a conductive metal nitride material. In some embodiments, the metallic material portion extends continuously as a continuous structure through each of the movable comb fingers. In some embodiments, the metallic material portion includes a region having a uniform width within each of the movable comb fingers. In some embodiments, the stationary structure includes a stationary comb structure comprising a plurality of stationary comb fingers interleaved with the movable comb fingers. In some embodiments, the movable comb fingers include an additional metallic material portion having the same material composition as the metallic material portion.

[0172] According to another embodiment of this disclosure, a microelectromechanical system (MEMS) device includes: a movable comb-like structure located in a cavity within a housing and including: a comb shaft portion; and a plurality of movable comb fingers projecting laterally from the comb shaft portion, wherein the movable comb-like structure includes a first metallic material portion; and a stationary structure fixed to the housing and including a second metallic material portion having the same material composition as the first metallic material portion, wherein the movable comb-like structure and the stationary structure are used to generate an electrical output signal based on a capacitance change between the movable comb-like structure and the stationary structure. In some embodiments, the MEMS device includes an accelerometer; the movable comb-like structure includes a first semiconductor material portion; and the stationary structure includes a second semiconductor material portion having the same material composition as the first semiconductor material portion. In some embodiments, the first metallic material portion extends continuously through each of the movable comb fingers; the stationary structure includes a plurality of stationary comb fingers interleaved with the movable comb fingers; and the second metallic material portion extends continuously through each of the stationary comb fingers.

[0173] According to another embodiment of this disclosure, a method for forming a microelectromechanical system (MEMS) device includes the following steps: forming a first trench and a second trench in a semiconductor matrix material layer; depositing at least one trench filling material in the first trench and the second trench, wherein the at least one trench filling material comprises a metallic material; and removing a portion of the semiconductor matrix material layer surrounding the first trench and the second trench, wherein multiple portions of the at least one trench filling material in the first trench include a movable comb structure, and multiple portions of the at least one trench filling material in the second trench include a stationary structure, and wherein the movable comb structure and the stationary structure are configured to generate an electrical output signal based on a capacitance change between the movable comb structure and the stationary structure. In some embodiments, the movable comb structure includes a comb shaft portion and a plurality of movable comb fingers projecting laterally from the comb shaft portion; and the stationary structure includes a plurality of stationary comb fingers interleaved with the movable comb fingers. In some embodiments, the method further includes the following steps: attaching a cap substrate to the semiconductor matrix material layer; after depositing the at least one trench fill material in the first trench and the second trench, masking multiple regions of the first trench and the second trench with a patterned etch mask layer; using the patterned etch mask layer as an etch mask to anisotropically etch multiple unmasked portions of the semiconductor matrix material layer; and selectively isotropically etching a semiconductor material of the semiconductor matrix material layer with respect to the at least one trench fill material in the first trench and the second trench. In some embodiments, the at least one trench fill material includes a semiconductor material deposited in the first trench and the second trench before or after the deposition of the metal material. In some embodiments, the at least one trench fill material includes a dielectric material deposited in the first trench and the second trench before the deposition of the metal material.

[0174] The foregoing has outlined features of several embodiments to enable those skilled in the art to better understand the nature of this disclosure. Those skilled in the art should understand that this disclosure can be readily used as the basis for designing or modifying other processes and structures to achieve the same purposes and / or advantages as the embodiments introduced herein. Those skilled in the art should also recognize that these equivalent constructions do not depart from the spirit and scope of this disclosure, and that various changes, substitutions, and modifications can be made without departing from the spirit and scope of this disclosure.

Claims

1. A microelectromechanical system device, characterized by comprises: a comb shaft portion; and a plurality of movable comb fingers protruding laterally from the comb shaft portion, wherein the movable comb structure comprises a metallic material portion and a semiconductor material portion in contact with the metallic material portion; and a stationary structure fixed to the housing, wherein the movable comb structure and the stationary structure are to generate an electrical output signal based on lateral movement of the movable comb structure relative to the stationary structure.

2. The microelectromechanical system device of claim 1, wherein The movable comb structure comprises a dielectric liner laterally surrounding the metallic material portion.

3. The microelectromechanical system device of claim 2, wherein The semiconductor material portion comprises a doped polysilicon-containing material having a p-type or n-type doping.

4. The microelectromechanical system device of claim 1, wherein The movable comb structure comprises a dielectric liner in contact with the metallic material portion.

5. The microelectromechanical system device of claim 4, wherein Surfaces of the dielectric liner are physically exposed to the cavity.

6. The microelectromechanical system device of claim 4, wherein: the metallic material portion is laterally surrounded by the dielectric liner; and the dielectric liner comprises a material selected from silicon oxide, silicon nitride, and a dielectric metal oxide.

7. The microelectromechanical system device of claim 1, wherein Surfaces of the metallic material portion are physically exposed to the cavity.

8. The microelectromechanical system device of claim 1, wherein The metallic material portion comprises a material selected from an elemental metal, an intermetallic alloy, a metal-semiconductor alloy, and an electrically conductive metal nitride material.

9. The microelectromechanical system device of claim 1, wherein The metallic material portion continuously extends as a continuous structure through each of the plurality of movable comb fingers.

10. The microelectromechanical system device of claim 9, wherein The metallic material portion comprises a region having a uniform width within each of the plurality of movable comb fingers.

11. The microelectromechanical system device of claim 1, wherein The stationary structure comprises a stationary comb structure including a plurality of stationary comb fingers interleaved with the plurality of movable comb fingers.

12. The microelectromechanical system device of claim 11, wherein The plurality of movable comb fingers comprises an additional metallic material portion having a same material composition as the metallic material portion.

13. A microelectromechanical system device, characterized by comprises: a movable comb structure located in a cavity within a housing and comprising: a comb shaft portion; and a plurality of movable comb fingers protruding laterally from the comb shaft portion, wherein the movable comb structure comprises a first metallic material portion and a first semiconductor material portion in contact with the first metallic material portion; and a stationary structure fixed to the housing and comprising a second metallic material portion having a same material composition as the first metallic material portion, wherein the movable comb structure and the stationary structure are to generate an electrical output signal based on a change in capacitance between the movable comb structure and the stationary structure.

14. The microelectromechanical system device of claim 13, wherein: the microelectromechanical system device comprises an accelerometer; and the stationary structure comprises a second semiconductor material portion having a same material composition as the first semiconductor material portion.

15. The microelectromechanical system device of claim 13, wherein: the first metallic material portion continuously extends through each of the plurality of movable comb fingers; the stationary structure includes a plurality of stationary comb fingers interleaved with the plurality of movable comb fingers; and the second metallic material portion continuously extends through each of the plurality of stationary comb fingers.

16. A method of forming a microelectromechanical system device, comprising: comprising the steps of: forming a first trench and a second trench in a semiconductor substrate material layer; depositing at least one trench fill material in the first trench and the second trench, wherein the at least one trench fill material comprises a metallic material; and removing a portion of the semiconductor substrate material layer around the first trench and the second trench, wherein portions of the at least one trench fill material in the first trench comprise a movable comb structure comprising a first metallic material portion and a first semiconductor material portion in contact with the first metallic material portion, and portions of the at least one trench fill material in the second trench comprise a stationary structure, and wherein the movable comb structure and the stationary structure are used to generate an electrical output signal based on a change in capacitance between the movable comb structure and the stationary structure.

17. The method of claim 16, wherein, The movable comb structure includes a comb shaft portion and a plurality of movable comb fingers projecting laterally from the comb shaft portion; and the stationary structure comprises a plurality of stationary comb fingers interleaved with the plurality of movable comb fingers.

18. The method of claim 16, wherein, further comprising the steps of: attaching a cap substrate to the semiconductor substrate material layer; after depositing the at least one trench fill material in the first trench and the second trench, masking regions of the first trench and the second trench with a patterned etch mask layer; anisotropically etching unmasked portions of the semiconductor substrate material layer using the patterned etch mask layer as an etch mask; and selectively isotropically etching a semiconductor material of the semiconductor substrate material layer for the at least one trench fill material in the first trench and the second trench.

19. The method of claim 16, wherein, The at least one trench fill material comprises a semiconductor material deposited in the first trench and the second trench prior to or after deposition of the metallic material.

20. The method of claim 16, wherein, The at least one trench fill material comprises a dielectric material deposited in the first trench and the second trench prior to deposition of the metallic material.

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