Capacitive acceleration sensor and method for manufacturing the same

Abstract

The application provides a capacitive acceleration sensor and a preparation method thereof. The method comprises the following steps: sequentially forming a first metal layer, a first dielectric layer, a sacrificial layer and a structure layer on the surface of a first substrate; bonding a second substrate with the surface of the structure layer of the first substrate; forming a first supporting hole column on the surface of the second substrate, the first supporting hole column penetrating through the second substrate and reaching the first dielectric layer; forming a second supporting hole column on the surface of the second substrate, the second supporting hole column penetrating through the second substrate and reaching the first metal layer; forming a strain structure on the second substrate, the center of the strain structure being arranged on the second supporting hole column, the surface of the strain structure being provided with a plurality of first recesses, etching the bottom of the first recesses to form a sacrificial hole, releasing the sacrificial layer through the sacrificial hole to form a cavity, and the sensor can be formed by bonding only once, the controllability is high, and the center of the strain structure is provided with the supporting hole column, so that the swing beam of the strain structure can generate a larger capacitance change under a smaller displacement, and the precision of the sensor is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor, in particular to a capacitive acceleration sensor and a preparation method thereof. BACKGROUND

[0002] Acceleration sensors can be implemented by micro-electro-mechanical systems (MEMS) manufactured on silicon wafers, and MEMS force balance accelerometers applying capacitive detection and electrostatic force feedback circuit are superior to other types of acceleration sensors in terms of high sensitivity, low noise, direct current response and bandwidth.

[0003] Current capacitive acceleration sensors are generally manufactured by manufacturing a substrate layer, a sensing layer and a packaging layer respectively, and manufacturing the three wafer layers through two bonding processes. However, this will cause the problem that the precision of the manufactured sensor is difficult to control.

[0004] Therefore, how to improve the controllability of the capacitive acceleration sensor during the manufacturing process, and improve the precision of the sensor, has become a technical problem to be solved in the industry at present. SUMMARY

[0005] The present application provides a capacitive acceleration sensor and a preparation method thereof, which solves the technical problem of how to improve the controllability of the capacitive acceleration sensor during the manufacturing process, and improve the precision of the sensor.

[0006] According to a first aspect of the present application, an embodiment of the present application provides a preparation method of a capacitive acceleration sensor, comprising:

[0007] S1: providing a first substrate and a second substrate;

[0008] S2: sequentially forming a first metal layer, a first dielectric layer, a sacrificial layer and a structure layer on the surface of the first substrate;

[0009] S3: bonding the second substrate and the structure layer surface of the first substrate;

[0010] S4: forming a first support hole column on the surface of the second substrate, the first support hole column penetrating through the second substrate until the first dielectric layer;

[0011] S5: forming a second support hole column on the surface of the second substrate, the second support hole column penetrating through the second substrate until the first metal layer;

[0012] S6: forming a strain structure on the second substrate, the center of the strain structure being arranged on the second support hole column, and the surface of the strain structure having a plurality of first recesses;

[0013] S7: etching the bottom of the first recess as the etching stop layer to form the sacrificial hole;

[0014] S8: releasing the sacrificial layer through the sacrificial hole to form a cavity.

[0015] Optionally, after bonding the second substrate with the structure layer surface of the first substrate, and before forming the first support hole column on the surface of the second substrate, the method further comprises:

[0016] Thinning the second substrate.

[0017] Optionally, the step S4 comprises:

[0018] S41: forming a first mask layer on the second substrate;

[0019] S42: performing first patterning on the first mask layer to form a first patterned mask layer;

[0020] S43: using the first patterned mask layer as a mask, and using the interface between the sacrificial layer and the first dielectric layer as an etching stop layer, sequentially etching the second substrate, the structure layer, and the sacrificial layer to form a second recess;

[0021] S44: filling a first support material into the second recess to form the first support hole column.

[0022] Optionally, the method for filling the first support material into the second recess comprises:

[0023] depositing silicon oxide in the second recess by chemical vapor deposition process, and the surface of the silicon oxide is flush with the surface of the first patterned mask layer.

[0024] Optionally, the method for filling the first support material into the second recess comprises:

[0025] alternately depositing silicon oxide material, silicon nitride material, and silicon oxide material into the second recess to form a composite support material, and the surface of the composite support material is flush with the surface of the first patterned mask layer.

[0026] Optionally, the second support hole column comprises a second dielectric layer and a metal connection layer, and the step S5 comprises:

[0027] S51: performing second patterning on the first mask layer to form a second patterned mask layer;

[0028] S52: etching the second substrate, the structure layer, the sacrificial layer and the first dielectric layer to form a third recess, taking the second patterned mask layer as a mask and taking the first metal layer as an etching stop layer;

[0029] S53: depositing the second dielectric layer on the sidewall of the third recess;

[0030] S54: filling the third recess with the metal connection layer, so that the metal connection layer is connected with the first metal layer;

[0031] S55: removing the second patterned mask layer, so that the metal connection layer is flush with the surface of the second substrate.

[0032] Optionally, the method for forming a strain structure on the second substrate comprises:

[0033] S61: forming a second mask layer on the second substrate;

[0034] S62: performing a third patterning on the second mask layer to form a third patterned mask layer, the third patterned mask layer pattern comprising at least one row of skeleton pattern and at least two oppositely arranged comb patterns, the branch strip pattern of the row of skeleton pattern being arranged in parallel and staggered with the comb teeth of the comb pattern;

[0035] S63: etching the second substrate to form a fourth recess, taking the third patterned mask layer as a mask and taking the structure layer as an etching stop layer;

[0036] S64: sequentially depositing a second metal layer and a third dielectric layer on the second substrate, the second metal layer and the third dielectric layer covering the surface of the fourth recess and covering other areas of the second substrate;

[0037] S65: removing the second metal layer and the third dielectric layer in the first area;

[0038] S66: removing the structure layer in the second area to form a strain structure, the strain structure comprising a row of skeleton swing beam and a comb-shaped fixed beam, the fixed beam being located on both sides of the swing beam, the comb teeth of the fixed beam being arranged in parallel and staggered with the branches of the swing beam.

[0039] Optionally, after forming the strain structure and before step S7, the method further comprises:

[0040] depositing a protective layer on the second substrate, the protective layer covering the surface of the fourth recess and covering other areas of the second substrate, so that the surface of the strain structure has a first recess.

[0041] Optionally, the sacrificial layer is an amorphous carbon layer, and the step S8 comprises:

[0042] The amorphous carbon layer is removed by oxidation, and the generated carbon dioxide gas is released through the sacrifice hole.

[0043] According to a second aspect of the present application, embodiments of the present application provide a capacitive acceleration sensor, comprising:

[0044] a first substrate;

[0045] a first metal layer formed on a surface of the first substrate;

[0046] a first dielectric layer formed on a surface of the first metal layer;

[0047] a structure layer formed on a surface of the first dielectric layer through a sacrificial layer, the sacrificial layer being an amorphous carbon layer;

[0048] a second substrate bonded on the structure layer of the first substrate;

[0049] a first support hole column penetrating through the second substrate to the first dielectric layer and surrounding the capacitive acceleration sensor;

[0050] a second support hole column penetrating through the second substrate to the first metal layer;

[0051] a second metal layer on a surface of the second substrate;

[0052] a third dielectric layer formed on the second metal layer;

[0053] wherein the second substrate, the second metal layer and the third dielectric layer constitute a strain structure, a center of the strain structure is arranged on the second support hole column, and a surface of the strain structure has a plurality of first recesses, so that the strain structure comprises a rack-like swing beam and a comb-like fixed beam, the fixed beam is located on both sides of the swing beam, and the comb teeth of the fixed beam and the branches of the swing beam are arranged in parallel and staggered.

[0054] wherein the sacrificial layer is removed after forming the first recesses to form a cavity between the structure layer and the first dielectric layer.

[0055] Compared with the prior art, the technical scheme of the embodiments of the present application has the following beneficial effects:

[0056] The capacitive acceleration sensor and the preparation method thereof have the following advantages: the method forms a first metal layer, a first dielectric layer, a sacrificial layer and a structure layer on the surface of a first substrate in sequence, bonds a second substrate and the structure layer surface of the first substrate, forms a first support hole column on the surface of the second substrate, the first support hole column penetrates through the second substrate and reaches the first dielectric layer, forms a second support hole column on the surface of the second substrate, the second support hole column penetrates through the second substrate and reaches the first metal layer, forms a strain structure on the second substrate, the center of the strain structure is arranged on the second support hole column, the surface of the strain structure has a plurality of first recesses, the bottom of the first recess is etched to form a sacrificial hole, the sacrificial layer is released through the sacrificial hole to form a cavity, and the sensor can be formed only by one bonding, and the controllability is high; meanwhile, the strain structure has a special shape, is more sensitive to external acceleration, and has the support hole column under the center, so that the swing beam can generate a larger capacitance change under a smaller displacement, and the precision of the sensor is improved. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0058] Figure 1 FIG. 1 is a flow diagram of a preparation method of a capacitive acceleration sensor in an embodiment of the present application;

[0059] Figures 2-5 FIG. 2 is a structural diagram of a preparation process of the capacitive acceleration sensor in the embodiment of the present application; Figure 1 ;

[0060] Figure 6 FIG. 3 is a flow diagram of a preparation method of a capacitive acceleration sensor in another embodiment of the present application;

[0061] Figures 7-10 FIG. 4 is a structural diagram of a preparation process of the capacitive acceleration sensor in the embodiment of the present application; Figure 2 ;

[0062] Figure 11 FIG. 5 is a flow diagram of a preparation method of a capacitive acceleration sensor in another embodiment of the present application;

[0063] Figures 12-16 FIG. 6 is a structural diagram of a preparation process of the capacitive acceleration sensor in the embodiment of the present application; Figure 3 ;

[0064] Figure 17is a flowchart of a preparation method of a capacitive acceleration sensor in another embodiment of the present application;

[0065] Figures 18-28 is a structural diagram of a preparation process of a capacitive acceleration sensor in an embodiment of the present application Figure 4 ;

[0066] Figure 29 is a top view of a capacitive acceleration sensor in an embodiment of the present application.

[0067] Label explanation:

[0068] 101 - first substrate;

[0069] 102 - first metal layer;

[0070] 103 - first dielectric layer;

[0071] 104 - sacrificial layer;

[0072] 105 - structure layer;

[0073] 201 - second substrate;

[0074] 301 - first mask layer;

[0075] 401 - first recess;

[0076] 402 - first support material;

[0077] 403 - first support hole column;

[0078] 500 - second support hole column

[0079] 501 - third recess;

[0080] 502 - second dielectric material layer;

[0081] 503 - second dielectric layer;

[0082] 504 - metal connection layer;

[0083] 601 - second mask layer;

[0084] 701 - fourth recess;

[0085] 702 - second metal layer;

[0086] 703 - third dielectric layer;

[0087] 704 - third mask layer;

[0088] 705 - fourth mask layer;

[0089] 801 - strain structure;

[0090] 8011 - ribbed swing beam;

[0091] 8012 - comb fixed beam;

[0092] 901 - protective layer;

[0093] 1001 - fixed beam lead capacitor. DETAILED DESCRIPTION

[0094] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0095] The terms "first", "second", "third", "fourth" and the like (if any) in the description, claims and above drawings of the present application are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series or unit does not necessarily limit to those clearly listed or units, but can include other or units not clearly listed or inherent to these processes, methods, products or devices.

[0096] The technical solutions of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in some embodiments.

[0097] As described in the background, the prior art is difficult to improve the controllability of the capacitive acceleration sensor in the manufacturing process, and to improve the accuracy of the sensor.

[0098] To solve the above problems, please refer to Figure 1 The present application provides a preparation method of a capacitive acceleration sensor, comprising:

[0099] S1: providing a first substrate and a second substrate;

[0100] S2: forming a first metal layer, a first dielectric layer, a sacrificial layer and a structure layer on the surface of the first substrate in sequence;

[0101] S3: bonding the second substrate with the structure layer surface of the first substrate;

[0102] S4: forming a first support hole column on the second substrate surface, the first support hole column penetrating through the second substrate to the first medium layer;

[0103] S5: forming a second support hole column on the second substrate surface, the second support hole column penetrating through the second substrate to the first metal layer;

[0104] S6: forming a strain structure on the second substrate, the center of the strain structure being arranged on the second support hole column, the surface of the strain structure having a plurality of first recesses;

[0105] S7: taking the sacrificial layer as an etching stop layer, etching the bottom of the first recess to form the sacrificial hole;

[0106] S8: releasing the sacrificial layer through the sacrificial hole to form a cavity.

[0107] Therefore, the forming method provided by the application can form a sensor only once by bonding, has higher controllability, and meanwhile, the strain structure has a support hole column under the center, so that the swing beam can generate larger capacitance change under smaller displacement, thereby improving the precision of the sensor.

[0108] Figures 2 to 28 is a cross-sectional structure diagram of a preparation process of a capacitive acceleration sensor of an embodiment of the application, Figure 29 is a top view of a capacitive acceleration sensor in an embodiment of the application, wherein two mutually perpendicular capacitive acceleration sensors and a first support hole column surrounding the two capacitive acceleration sensors are shown, and the two mutually perpendicular capacitive acceleration sensors are respectively used for detecting acceleration components in different directions, so as to realize acceleration detection in a two-dimensional plane.

[0109] Please continue to refer to Figure 29 It can be seen that for a single capacitive acceleration sensor, the strain structure of the application includes a swing beam in the middle and fixed beams on both sides, when the swing beam moves or deforms, the distance between the swing beam and the fixed beams will change, thereby changing the capacitance value between them, and the capacitance value will be used for subsequent further signal processing or data acquisition.

[0110] It should be understood that the application is not limited to the number and position of the capacitive acceleration sensors, and the capacitive acceleration sensors can be flexibly arranged according to actual needs, for example, a plurality of capacitive acceleration sensors are arranged at different positions and directions to realize more comprehensive acceleration component detection.

[0111] For the convenience of understanding the structure, the cross-sectional structure schematic diagram provided by the application is cut along the A-A' line in Figure 29 . On this basis, please refer to Figure 1 , and in combination with Figures 2-28 , the preparation process of the capacitive acceleration sensor provided by the embodiment of the application is described.

[0112] Please refer to Figure 2 , to provide a first substrate 101 and a second substrate 201.

[0113] As an example, the first substrate 101 or the second substrate 201 can be an SOI substrate, a silicon substrate, etc., and the application does not limit this. Those skilled in the art can select a suitable substrate according to the needs.

[0114] Please refer to Figure 3 , a first metal layer 102, a first dielectric layer 103, a sacrificial layer 104 and a structure layer 105 are sequentially formed on the surface of the first substrate 101.

[0115] As an example, the material of the first metal layer 102 can be a metal material with good conductivity such as Al, Au, etc., the material of the first dielectric layer 103 can be silicon oxide, silicon nitride, etc., and the structure layer 105 can be silicon oxide, etc. Those skilled in the art can select a suitable material according to the specific process requirements and conditions.

[0116] In one embodiment, the sacrificial layer 104 is a carbon structure layer. As an example, the carbon structure layer can be an amorphous carbon layer or a graphite layer.

[0117] In the case of an amorphous carbon layer, an amorphous carbon layer with a predetermined thickness can be sequentially formed on the surface of the first dielectric layer 103 by physical vapor deposition (PVD) or chemical vapor deposition (CVD).

[0118] Please refer to Figure 4 , the second substrate 201 is bonded to the surface of the structure layer 105 of the first substrate 101, so that the first substrate 101 and the second substrate 201 are bonded.

[0119] In a preferred embodiment, after the first substrate 101 and the second substrate 201 are bonded, please refer to Figure 5 , the second substrate 201 is thinned.

[0120] As an example, the thickness of the second substrate 201 can be controlled to be 20um-200um. Of course, the required thickness of the second substrate 201 is related to the device capacitance value and the final sensitivity, and the application does not limit this. Those skilled in the art can select a suitable thickness according to the needs.

[0121] Please continue to refer to Figure 1 , execute step S4: forming a first support hole column on the surface of the second substrate 201, the first support hole column penetrates through the second substrate 201 until the first dielectric layer 103.

[0122] In an embodiment, please refer to Figure 6 , Figure 6 The flow chart of step S4, including:

[0123] S41: forming a first mask layer on the second substrate;

[0124] S42: performing first patterning on the first mask layer to form a first patterned mask layer;

[0125] S43: taking the first patterned mask layer as a mask, taking the interface between the sacrificial layer and the first dielectric layer as an etching stop layer, etching the second substrate, the structure layer, and the sacrificial layer in sequence to form a second recess;

[0126] S44: filling the support material into the second recess to form the first support hole column.

[0127] The subsequent combination Figures 7-10 will be described.

[0128] Please refer to Figure 7 , forming a first mask layer 301 on the second substrate 201; performing first patterning on the first mask layer 301 to form a first patterned mask layer.

[0129] Please refer to Figure 8 , taking the first patterned mask layer as a mask, taking the interface between the sacrificial layer 104 and the first dielectric layer 103 as an etching stop layer, etching the second substrate 201, the structure layer 105, and the sacrificial layer 104 in sequence to form a second recess 401;

[0130] Please refer to Figure 9 , filling the first support material 402 into the second recess 401.

[0131] In an embodiment, the first support material 402 can be filled into the first recess 401 by high-density plasma process (HDP), high-aspect-ratio process (HARP), flowable chemical vapor deposition process (FCVD), etc.

[0132] In a specific embodiment, the method of filling the first support material 402 into the first recess 401, comprising:

[0133] Silicon oxide is deposited in the first recess 401 by a chemical vapor deposition process, and the surface of the silicon oxide is flush with the surface of the first patterned mask layer.

[0134] In another specific embodiment, the method of filling the first recess 401 with a first support material 402 includes:

[0135] Silicon oxide material, silicon nitride material, and silicon oxide material are alternately deposited in the first recess 401 to form a composite first support material, and the surface of the composite first support material is flush with the surface of the first patterned mask layer.

[0136] In this way, the first support hole column surrounds the area where the sensor is formed and is connected to the structure layer 105, providing support for the subsequent formation of a fixed beam structure, which can improve the support strength of the fixed beam.

[0137] As a specific embodiment, in step S44, the method of forming the first support hole column includes:

[0138] The first support material 402 on the surface of the second substrate 201 is removed by chemical mechanical polishing planarization treatment with the first mask layer 301 as an etching stop layer to form the first support hole column 403.

[0139] Specifically, referring to Figure 10 The first support material 402 on the surface of the second substrate 201 is removed by chemical mechanical polishing planarization treatment with the first mask layer 301 as an etching stop layer to form the first support hole column 403.

[0140] Please continue to refer to Figure 1 Step S5 is performed to form a second support hole column on the surface of the second substrate, and the second support hole column penetrates through the second substrate to the first metal layer.

[0141] In one embodiment, the second support hole column includes a second dielectric layer and a metal connection layer, in which case, please refer to Figure 11 , Figure 11 The flowchart of step S5 includes:

[0142] S51: The first mask layer is patterned a second time to form a second patterned mask layer;

[0143] S52: The second substrate, the structure layer, the sacrificial layer, and the first dielectric layer are etched with the second patterned mask layer as a mask and the first metal layer as an etching stop layer to form a third recess;

[0144] S53: depositing the second dielectric layer on the sidewall of the third recess;

[0145] S54: filling the third recess with the metal connection layer, so that the metal connection layer is connected with the first metal layer;

[0146] S55: removing the second patterned mask layer, so that the metal connection layer is flush with the surface of the second substrate.

[0147] In one embodiment, the method of depositing the second dielectric layer on the sidewall of the third recess in step S53 comprises:

[0148] depositing a second dielectric material layer on the second substrate, the second dielectric material layer covering the surface of the third recess and covering other areas of the second substrate;

[0149] performing etching on the second dielectric material layer on the surface of the second substrate and the second dielectric material layer at the bottom of the third recess, to form the second dielectric layer.

[0150] Subsequent combination Figures 12-16 will be described.

[0151] Please refer to Figure 12 performing second patterning on the first mask layer 301 to form a second patterned mask layer; taking the second patterned mask layer as a mask and taking the first metal layer 102 as an etching stop layer, performing etching on the second substrate 201, the structure layer 105, the sacrificial layer 104 and the first dielectric layer 103 to form the third recess 501.

[0152] Please refer to Figure 13 depositing a second dielectric material layer 502 on the second substrate 201, the second dielectric material layer 502 covering the surface of the third recess 501 and covering other areas of the second substrate 201.

[0153] Please refer to Figure 14 performing etching on the second dielectric material layer 502 on the surface of the second substrate 201 and the second dielectric material layer 502 at the bottom of the third recess 501 to form the second dielectric layer 503.

[0154] In one specific embodiment, performing dry etching on the second dielectric material layer 502 on the surface of the second substrate 201 and the second dielectric material layer 502 at the bottom of the third recess 501 to form the second dielectric layer 503.

[0155] As an example, the material of the second dielectric layer 503 can be silicon oxide, silicon nitride, etc. The present application does not limit this, and those skilled in the art can select appropriate materials as needed.

[0156] Please refer to Figure 15 The metal connection layer 504 is filled into the third recess 501, so that the metal connection layer 504 is connected with the first metal layer 102.

[0157] As an example, the material of the metal connection layer 504 can be a metal layer, a doped polysilicon layer, etc. The present application does not limit this, and those skilled in the art can select appropriate materials as needed.

[0158] Please refer to Figure 16 The second patterned mask layer 301 is removed, so that the metal connection layer 504 is flush with the surface of the second substrate 201.

[0159] Please continue to refer to Figure 1 Step S6: a strain structure is formed on the second substrate, the center of the strain structure is arranged on the second support hole column, and the surface of the strain structure has a plurality of first recesses.

[0160] Regarding the method of forming a strain structure on the second substrate, in one embodiment, please refer to Figure 17 , Figure 17 is a flowchart of step S6, which includes:

[0161] S61: a second mask layer is formed on the second substrate;

[0162] S62: the second mask layer is patterned for the third time to form a third patterned mask layer, the pattern of the third patterned mask layer includes at least one row of skeleton pattern and at least two oppositely arranged comb patterns, the branch strip patterns of the row of skeleton pattern are arranged in parallel and staggered with the comb teeth of the comb pattern;

[0163] S63: taking the third patterned mask layer as a mask and the structure layer as an etching stop layer, the second substrate is etched to form a fourth recess;

[0164] S64: a second metal layer and a third dielectric layer are sequentially deposited on the second substrate, the second metal layer and the third dielectric layer cover the surface of the fourth recess and cover other areas of the second substrate;

[0165] S65: the second metal layer and the third dielectric layer in the first area are removed;

[0166] S66: removing the structure layer of the second region to form a strained structure, the strained structure comprising a row-bone-shaped swing beam and a comb-shaped fixed beam, the fixed beam being located on both sides of the swing beam, and the comb teeth of the fixed beam being arranged in parallel and staggered with the branches of the swing beam.

[0167] Subsequent combination Figures 18-21 The application will be described in detail.

[0168] Please refer to Figure 18 , a second mask layer 601 is formed on the second substrate 201; the second mask layer 601 is patterned for the third time to form a third patterned mask layer, the third patterned mask layer pattern comprising at least one row skeleton pattern and at least two oppositely arranged comb patterns, the branch strip pattern of the row skeleton pattern being arranged in parallel and staggered with the comb teeth of the comb pattern; taking the third patterned mask layer as a mask and taking the structure layer 105 as an etching stop layer, the second substrate 201 is etched to form a fourth recess 701.

[0169] As an example, the size of the fourth recess 701 can be between 5nm-10nm, of course, the application does not limit this, and the specific size depends on the design requirements.

[0170] After this step, it also includes removing the second mask layer 601.

[0171] Please continue to refer to Figure 19 , a second metal layer 702 and a third dielectric layer 703 are sequentially deposited on the second substrate 201, the second metal layer 702 and the third dielectric layer 703 covering the surface of the fourth recess 701 and covering other areas of the second substrate 201.

[0172] As an example, the thickness of the second metal layer 702 can be 1nm-100nm, and the thickness of the third dielectric layer 703 can be 10nm-1000nm, the application does not limit this, and those skilled in the art can select a suitable thickness according to the needs.

[0173] In actual application, in a specific embodiment, the material of the third dielectric layer 703 can be silicon oxide, silicon nitride, silicon oxynitride, etc., and the application does not limit this.

[0174] On this basis, step S66 is continued: removing the second metal layer 702 and the third dielectric layer 703 of the first region; removing the structure layer 105 of the second region to form a strained structure, the strained structure comprising a row-bone-shaped swing beam and a comb-shaped fixed beam, the fixed beam being located on both sides of the swing beam, and the comb teeth of the fixed beam being arranged in parallel and staggered with the branches of the swing beam.

[0175] The formed strain structure can be as shown in Figure 29 In an example of Figure 29 The strain structure 801 includes a rib-like swing beam 8011 and a comb-like fixed beam 8012, the fixed beam 8012 is located on both sides of the swing beam 8011, and the comb teeth of the fixed beam 8012 are arranged in parallel and staggered with the branches of the swing beam 8011.

[0176] The subsequent Figures 20-22 will be described.

[0177] Please refer to Figure 20 , a patterned third mask layer 704 is formed on the second metal layer 703; the area outside the patterned third mask layer 704 is the first area, and the second metal layer 702 and the third dielectric layer 703 in the first area can be removed by dry etching.

[0178] The first area corresponds to the surface of the second substrate 201 outside the part of the rib-like swing beam corresponding to the second support hole column;

[0179] Please refer to Figure 21 , a patterned fourth mask layer 705 is formed on the second substrate 201 and the remaining second metal layer 703, and the area outside the patterned fourth mask layer 705 corresponds to the second area, and the structure layer in the second area is removed by dry etching.

[0180] The second area corresponds to the gap between the branch strips of the rib-like swing beam, the gap between the comb teeth of the comb-like fixed beam, and the gap between the rib-like swing beam and the comb-like fixed beam, that is, the gap between the swing beam and the fixed beam of the strain structure. Figure 29 The white part outside the strain structure (801) in the figure, that is, the second metal layer 703, the third dielectric layer 702 and the structure layer in the second area are removed to form a strain structure; the side wall of the rib-like swing beam structure and the side wall of the comb-like fixed beam are provided with the second metal layer 703 and the third dielectric layer 702, as shown in Figures 25-28 .

[0181] Please refer to Figure 22 , the third mask layer 704 and the fourth mask layer 705 are removed.

[0182] In Figure 22In the example shown in FIG. 7, the second metal layer 702 and the third dielectric layer 703 of the portion of the swing beam corresponding to the second support hole post are not removed, because the second metal layer 702 and the third dielectric layer 703 serve as the plates of the capacitor, enabling transmission of the electrical signal, while the second metal layer 702 and the third dielectric layer 703 of the portion of the swing beam corresponding to the second support hole post are removed to enable electrical conduction between the structure layer and the second support hole post.

[0183] Please refer to Figure 23 A protective layer 901 is deposited on the second substrate 201, covering the surface of the fourth recess 701 and other areas of the second substrate 201, so that the surface of the strain structure has a first recess.

[0184] For example, the material of the protective layer 901 can be a silicon nitride layer, a silicon oxide layer, or a composite layer of silicon oxide and silicon nitride, and the present application is not limited in this regard.

[0185] Please refer to Figure 24 The bottom of the first recess is etched to form a sacrificial hole, with the sacrificial layer 104 as the etching stop layer.

[0186] In a specific embodiment, the bottom of the first recess can be etched by dry etching to form the sacrificial hole.

[0187] Please refer to Figure 25 The sacrificial layer 104 is released through the sacrificial hole to form a cavity.

[0188] In the case where the sacrificial layer 104 is an amorphous carbon layer, a specific embodiment of the step S8 includes:

[0189] The amorphous carbon layer is removed by oxidation, and the generated carbon dioxide gas is released through the sacrificial hole.

[0190] For the convenience of understanding the structure of other parts after the cavity is formed, please refer to Figures 26-28 .

[0191] Among them, Figure 26 shows a cross-sectional structure schematic diagram along the line B-B' in Figure 28 .

[0192] Figure 27 shows a cross-sectional structure schematic diagram along the line C-C' in Figure 28 .

[0193] Figure 28 A cross-sectional structure schematic diagram is shown along the line D-D' in Figure 29 A cross-sectional structure schematic diagram is shown along the line D-D' in

[0194] In summary, in the preparation method of the technical scheme of the present application, a first metal layer, a first dielectric layer, a sacrificial layer and a structure layer are sequentially formed on the surface of a first substrate, a second substrate is bonded to the surface of the structure layer of the first substrate, a first support hole column is formed on the surface of the second substrate, the first support hole column penetrating through the second substrate to the first dielectric layer, a second support hole column is formed on the surface of the second substrate, the second support hole column penetrating through the second substrate to the first metal layer, a strain structure is formed on the second substrate, the center of the strain structure is arranged on the second support hole column, the surface of the strain structure has a plurality of first recesses, the bottom of the first recess is etched to form a sacrificial hole, the sacrificial layer is released through the sacrificial hole to form a cavity, and the sensor can be formed only once through bonding, the controllability is high, at the same time, the strain structure is interlaced with the comb-shaped fixed beam and the row-bone-shaped swing beam, the acceleration of the external environment is more sensitive, and the swing beam can produce a larger capacitance change under a very small displacement, so that the precision of the sensor is improved.

[0195] Correspondingly, the present application also provides a capacitive acceleration sensor, please continue to refer to Figure 25 , comprising:

[0196] a first substrate 101;

[0197] a first metal layer 102 formed on the surface of the first substrate 101;

[0198] a first dielectric layer 103 formed on the surface of the first metal layer 102;

[0199] a structure layer 105 formed on the surface of the first dielectric layer 103 through a sacrificial layer 104, the sacrificial layer 104 being an amorphous carbon layer;

[0200] a second substrate 201 bonded to the structure layer 105 of the first substrate 101;

[0201] a first support hole column 403 penetrating through the second substrate 201 to the first dielectric layer 103, and surrounding the capacitive acceleration sensor;

[0202] a second support hole column 500, the second support hole column 500 penetrating through the second substrate 201 to the first metal layer 102;

[0203] a second metal layer 702 located on the surface of the second substrate 201;

[0204] a third dielectric layer 703 formed on the second metal layer 702;

[0205] The second substrate 201, the second metal layer 702 and the third dielectric layer 703 form a strain structure, and the center of the strain structure is arranged on the second support column 500, and the surface of the strain structure has a plurality of first recesses, so that the strain structure includes a row-bone-shaped swing beam and a comb-shaped fixed beam, the fixed beam is located on both sides of the swing beam, and the comb teeth of the fixed beam are arranged in parallel and staggered with the branches of the swing beam.

[0206] The sacrificial layer 104 is removed after forming the first recess to form a cavity between the structure layer 105 and the first dielectric layer 103.

[0207] In the example, the capacitive acceleration sensor further comprises a protective layer 901 covering the surface of the strain structure and the surface of the swing beam support column structure, so as to protect the surface of the capacitive acceleration sensor and avoid damage to the sensor in subsequent processes. Figure 25

[0208] Please refer to Figure 29 , Figure 29 for Figure 25 the corresponding top view. In actual application, the sensitivity of the sensor can be adjusted by adjusting the size of the swing beam; moreover, the support column of the swing beam can be one or more, and the specific number is designed according to the design requirement.

[0209] In the example, the capacitive acceleration sensor further comprises a fixed beam lead capacitor 1001, and the metal wire at the bottom of the swing beam support column is another lead electrode of the capacitor. Figure 29 The fixed beam lead capacitor 1001 serves as a signal output end of the capacitive sensor. When the swing beam moves or deforms, the distance between the swing beam and the fixed beam changes, thereby changing the capacitance value therebetween, and the fixed beam lead capacitor 1001 captures the change and converts it into an electric signal, which is transmitted to the electronic circuit at the back end for further signal processing or data acquisition.

[0210] It can be seen that in the capacitive acceleration sensor of the technical scheme, only one bonding is needed to form the sensor, and the controllability is high, at the same time, the strain structure is the comb-shaped fixed beam and the row-bone-shaped swing beam which are staggered with each other, and the center is supported by the hole column, so that the swing beam can produce a larger capacitance change under a small displacement, thereby improving the precision of the sensor.

[0211]

[0212] ​​It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for manufacturing a capacitive acceleration sensor, characterized by, The method comprises the following steps: S1: providing a first substrate and a second substrate; S2: sequentially forming a first metal layer, a first dielectric layer, a sacrificial layer and a structure layer on a surface of the first substrate; S3: bonding the second substrate with the structure layer surface of the first substrate; S4: forming a first support hole column on the surface of the second substrate, the first support hole column penetrating through the second substrate until the first dielectric layer; S5: forming a second support hole column on the surface of the second substrate, the second support hole column penetrating through the second substrate until the first metal layer; S6: forming a strain structure on the second substrate, the center of the strain structure being arranged on the second support hole column, the surface of the strain structure having a plurality of first recesses, the strain structure comprising a row-bone-shaped swing beam and a comb-shaped fixed beam, the fixed beam being located on both sides of the swing beam, the comb teeth of the fixed beam being arranged in parallel and staggered with the branches of the swing beam; S7: taking the sacrificial layer as an etching stop layer, etching the bottom of the first recess to form the sacrificial hole; S8: releasing the sacrificial layer through the sacrificial hole to form a cavity.

2. The method of claim 1, wherein the method further comprises forming a plurality of conductive lines on the substrate. After the second substrate is bonded with the structure layer surface of the first substrate, and before the first support hole column is formed on the surface of the second substrate, the method further comprises: Thinning the second substrate.

3. The method of claim 1, wherein the method further comprises forming a plurality of conductive lines on the substrate, and forming a plurality of insulating layers on the substrate, wherein the plurality of insulating layers and the plurality of conductive lines are alternately stacked on the substrate. The step S4 comprises: S41: forming a first mask layer on the second substrate; S42: performing first patterning on the first mask layer to form a first patterned mask layer; S43: taking the first patterned mask layer as a mask and taking the interface between the sacrificial layer and the first dielectric layer as an etching stop layer, sequentially etching the second substrate, the structure layer and the sacrificial layer to form a second recess; S44: filling a first support material into the second recess to form the first support hole column.

4. The method for fabricating a capacitive accelerometer as described in claim 3, characterized in that, The method for filling the first support material into the second recess comprises: Depositing silicon oxide in the second recess by using a chemical vapor deposition process, and the surface of the silicon oxide is flush with the surface of the first patterned mask layer.

5. The method of claim 3, wherein the step of forming the capacitor is performed by forming a first electrode on the substrate, forming a second electrode on the substrate, and forming a dielectric layer between the first and second electrodes. The method for filling the first support material into the second recess comprises: Alternately depositing silicon oxide material, silicon nitride material and silicon oxide material into the second recess to form a composite support material, and the surface of the composite support material is flush with the surface of the first patterned mask layer.

6. The method of manufacturing a capacitive acceleration sensor according to claim 3, wherein The second support hole column comprises a second dielectric layer and a metal connecting layer, and the step S5 comprises: S51: performing second patterning on the first mask layer to form a second patterned mask layer; S52: taking the second patterned mask layer as a mask and taking the first metal layer as an etching stop layer, etching the second substrate, the structure layer, the sacrificial layer and the first dielectric layer to form a third recess; S53: depositing the second dielectric layer on the sidewall of the third recess; S54: filling the metal connecting layer into the third recess so that the metal connecting layer is connected with the first metal layer; S55: removing the second patterned mask layer so that the metal connection layer is flush with the surface of the second substrate.

7. The method for fabricating a capacitive accelerometer as described in claim 1, characterized in that, A method for forming a strain structure on a second substrate, comprising: S61: forming a second mask layer on the second substrate; S62: performing a third patterning on the second mask layer to form a third patterned mask layer, the third patterned mask layer pattern comprising at least one row of skeleton pattern and at least two oppositely arranged comb patterns, the branch strip pattern of the row skeleton pattern being arranged in parallel and staggered with the comb teeth of the comb pattern; S63: etching the second substrate with the third patterned mask layer as a mask and the structure layer as an etching stop layer to form a fourth recess; S64: sequentially depositing a second metal layer and a third dielectric layer on the second substrate, the second metal layer and the third dielectric layer covering the surface of the fourth recess and covering other areas of the second substrate; S65: removing the second metal layer and the third dielectric layer in the first area; S66: removing the structure layer in the second area to form a strain structure.

8. The method for fabricating a capacitive accelerometer as described in claim 7, characterized in that, After forming the strain structure and before step S7, further comprising: depositing a protective layer on the second substrate, the protective layer covering the surface of the fourth recess and covering other areas of the second substrate, so that the surface of the strain structure has a first recess.

9. The method for fabricating a capacitive accelerometer as described in claim 1, characterized in that, The sacrificial layer is an amorphous carbon layer, and the step S8 comprises: oxidizing and removing the amorphous carbon layer, and releasing the generated carbon dioxide gas through the sacrificial hole.

10. A capacitive acceleration sensor, characterized by Comprise: a first substrate; a first metal layer formed on the surface of the first substrate; a first dielectric layer formed on the surface of the first metal layer; a structure layer formed on the surface of the first dielectric layer through a sacrificial layer, the sacrificial layer being an amorphous carbon layer; a second substrate bonded to the structure layer of the first substrate; a first support hole column penetrating through the second substrate to the first dielectric layer and surrounding the capacitive acceleration sensor; a second support hole column penetrating through the second substrate to the first metal layer; a second metal layer on the surface of the second substrate; a third dielectric layer formed on the second metal layer; wherein the second substrate, the second metal layer and the third dielectric layer constitute a strain structure, and the center of the strain structure is arranged on the second support hole column, the surface of the strain structure has a plurality of first recesses, so that the strain structure comprises a row of skeleton swing beam and a comb fixed beam, the fixed beam is located on both sides of the swing beam, and the comb teeth of the fixed beam are arranged in parallel and staggered with the branches of the swing beam; wherein the sacrificial layer is removed after forming the first recess to form a cavity between the structure layer and the first dielectric layer.

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