MEMS device and method of manufacturing the same

Abstract

The application provides a MEMS device and a manufacturing method thereof, the manufacturing method of the MEMS device comprising the following steps: a first surface of a second substrate is provided with a first MEMS structure and a second MEMS structure, the first substrate comprises a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure; a sacrificial layer and a protective layer are sequentially formed on the first surface of the first substrate; a first cavity and a first pumping hole are formed in the first region, and a second cavity is formed in the second region; a second surface of the first substrate is bonded with the first surface of the second substrate; a plurality of second pumping holes are formed in the protective layer; a third cavity is formed in the sacrificial layer; the second pumping holes are communicated with the third cavity; the first cavity is pumped through the second pumping holes, the third cavity and the first pumping hole, and a metal layer is filled in the second pumping holes. The technical scheme of the application can realize the sealing of the pumping hole without using a laser sealing process, solves the problem of sealing of a large-size pumping hole, and reduces the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a MEMS device and a manufacturing method thereof. BACKGROUND

[0002] In order to integrate different MEMS devices (such as accelerometers and gyroscopes) with different vacuum degrees in the same wafer, as shown in the prior art, a first substrate 11 is bonded with a second substrate 12, and the vacuum degrees of part of the MEMS devices are adjusted during the bonding; and the second substrate 12 is etched with a pumping hole 121, and the pumping hole 121 is used for pumping to improve the vacuum degree of the cavity connected with the pumping hole 121, that is, the vacuum degrees of the remaining part of the MEMS devices are adjusted through the pumping hole 121, and after the vacuum degree reaches the requirement, a laser hole sealing process is used to seal the pumping hole 121 one by one by using a special machine. Figure 1

[0003] However, when the thickness of the second substrate 12 is very thick, the width of the pumping hole 121 formed by etching in the second substrate 12 is large due to the influence of the etching process capability, which leads to poor effect of sealing the pumping hole 121 by using the laser hole sealing process or even cannot be sealed; and the special machine used in the laser hole sealing process is expensive, and sealing the pumping hole 121 one by one during operation leads to low sealing efficiency, and thus leads to high cost.

[0004] Therefore, it is necessary to improve the hole sealing process of the pumping hole to avoid the above problems. SUMMARY

[0005] The present application aims to provide a MEMS device and a manufacturing method thereof, which can realize the sealing of the pumping hole without using the laser hole sealing process, solve the problem of sealing the large-size pumping hole, and reduce the cost.

[0006] To achieve the above-mentioned purpose, the present application provides a manufacturing method of a MEMS device, comprising:

[0007] providing a first substrate and a second substrate, a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure, and the first substrate comprises a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure;

[0008] forming a sacrificial layer and a protective layer on the first surface of the first substrate in sequence, and the protective layer covers the sacrificial layer;

[0009] etching a second surface of the first substrate to form a first cavity and a first pumping hole in the first region, and to form a second cavity in the second region, and the first pumping hole exposes the sacrificial layer;​

[0010] bonding a second surface of the first substrate with a first surface of the second substrate, the first evacuation hole being in communication with the first cavity after the bonding;

[0011] forming a plurality of second evacuation holes in the protective layer; before the bonding of the second surface of the first substrate with the first surface of the second substrate, releasing part of the sacrificial layer through the first evacuation hole to form a third cavity in the sacrificial layer; or, after the forming of the plurality of second evacuation holes in the protective layer, releasing part of the sacrificial layer through the second evacuation hole to form a third cavity in the sacrificial layer; the second evacuation hole being in communication with the third cavity;

[0012] evacuating the first cavity through the second evacuation hole, the third cavity and the first evacuation hole, and filling a metal layer in the second evacuation hole.

[0013] Optionally, the first evacuation hole and the second evacuation hole are staggered in position.

[0014] Optionally, the width of the second evacuation hole is smaller than the width of the first evacuation hole.

[0015] Optionally, the width of the first evacuation hole is 10-20 μm, and the width of the second evacuation hole is 1-5 μm.

[0016] Optionally, the second surface of the first region further forms a fourth cavity; the steps of forming the first cavity, the first evacuation hole and the fourth cavity in the first region, and forming the second cavity in the second region, comprise:

[0017] etching the second surface of the first substrate to form the first cavity and the fourth cavity in the first region, and to form the second cavity in the second region;

[0018] etching a bottom wall of the fourth cavity to form the first evacuation hole in the bottom wall of the fourth cavity.

[0019] Optionally, before the etching of the second surface of the first substrate, the method for manufacturing the MEMS device further comprises:

[0020] forming a first bonding ring on the second surface of the first substrate;

[0021] before the bonding of the second surface of the first substrate with the first surface of the second substrate, the method for manufacturing the MEMS device further comprises:

[0022] forming a second bonding ring on the first surface of the second substrate;

[0023] The bonding of the second surface of the first substrate to the first surface of the second substrate comprises bonding the second surface of the first substrate to the first surface of the second substrate through the first bonding ring and the second bonding ring.

[0024] Optionally, the first MEMS structure comprises a comb structure of a gyroscope, and the second MEMS structure comprises a comb structure of an accelerometer.

[0025] The application further provides a MEMS device, comprising:

[0026] a second substrate, a first surface of the second substrate being formed with a first MEMS structure and a second MEMS structure;

[0027] a first substrate, a second surface of the first substrate being bonded to the first surface of the second substrate; the first substrate comprising a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure, a second surface of the first region being formed with a first cavity and a first evacuation hole, a second surface of the second region being formed with a second cavity; a first surface of the first substrate being covered with a sacrificial layer and a protective layer, the protective layer covering the sacrificial layer, a third cavity being formed in the sacrificial layer, a plurality of second evacuation holes being formed in the protective layer, the first evacuation hole being in communication with the first cavity and the third cavity respectively, the third cavity being in communication with the second evacuation hole; the second evacuation hole being filled with a metal layer.

[0028] Optionally, the first evacuation hole and the second evacuation hole are staggered in position.

[0029] Optionally, the width of the second evacuation hole is smaller than the width of the first evacuation hole.

[0030] Optionally, the width of the first evacuation hole is 10-20 μm, and the width of the second evacuation hole is 1-5 μm.

[0031] Optionally, the second surface of the first region is further formed with a fourth cavity in communication with the first evacuation hole, the first evacuation hole being located between the third cavity and the fourth cavity.

[0032] Optionally, the MEMS device further comprises:

[0033] a first bonding ring formed on the second surface of the first substrate;

[0034] a second bonding ring formed on the first surface of the second substrate, the second surface of the first substrate being bonded to the first surface of the second substrate through the first bonding ring and the second bonding ring.

[0035] Optionally, the first MEMS structure comprises a comb structure of a gyroscope, and the second MEMS structure comprises a comb structure of an accelerometer.

[0036] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0037] 1. The manufacturing method of the MEMS device, by sequentially forming a sacrificial layer and a protective layer on the first surface of the first substrate; etching the second surface of the first substrate to form a first cavity and a first pumping hole in the first region, and to form a second cavity in the second region, the first pumping hole exposes the sacrificial layer; and after bonding the second surface of the first substrate with the first surface of the second substrate, forming a plurality of second pumping holes in the protective layer; and forming a third cavity in the sacrificial layer which communicates with the second pumping hole and the first pumping hole; pumping the first cavity through the second pumping hole, the third cavity and the first pumping hole, and filling a metal layer in the second pumping hole, so that the sealing of the pumping hole can be realized without using the laser sealing process, at the same time, the problem of sealing large-size pumping hole can be solved, and the cost is reduced.

[0038] 2. The MEMS device, comprising: a second substrate, a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure; a first substrate, a second surface of the first substrate is bonded on the first surface of the second substrate; the first substrate comprises a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure, a second surface of the first region is formed with a first cavity and a first pumping hole, and a second surface of the second region is formed with a second cavity; a first surface of the first substrate is covered with a first sacrificial layer and a protective layer, the protective layer covers the first sacrificial layer, a third cavity is formed in the first sacrificial layer, a plurality of second pumping holes are formed in the protective layer, the first pumping hole respectively communicates with the first cavity and the third cavity, and the third cavity communicates with the second pumping hole; a metal layer is filled in the second pumping hole, so that the sealing of the pumping hole can be realized without using the laser sealing process, at the same time, the problem of sealing large-size pumping hole can be solved, and the cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a cross-sectional schematic view of a MEMS device;

[0040] Figure 2 is a flow chart of the manufacturing method of the MEMS device according to an embodiment of the present application;

[0041] Figures 3a to 3k is Figure 2A cross-sectional view of a device in a manufacturing method of a MEMS device.

[0042] wherein the Figures 1 to 3k The reference signs in the drawings are explained as follows:

[0043] 11-first substrate; 12-second substrate; 121-pumping hole; 21-first substrate; 211-first cavity; 212-second cavity; 213-first pumping hole; 214-fourth cavity; 22-first sacrificial layer; 221-third cavity; 23-protective layer; 231-second pumping hole; 24-first bonding ring; 25-gas absorption layer; 31-second substrate; 311-semiconductor base; 312-first insulating medium layer; 313-conductive structure; 314-second sacrificial layer; 3141-fifth cavity; 315-semiconductor layer; 3151-releasing hole; 316-second insulating medium layer; 32-second bonding ring; 41-metal layer. DETAILED DESCRIPTION

[0044] An embodiment of the present application provides a manufacturing method of a MEMS device, referring to Figure 2 , Figure 2 FIG. 1 is a flowchart of a manufacturing method of a MEMS device according to an embodiment of the present application, and the manufacturing method of the MEMS device comprises:

[0045] S1, providing a first substrate and a second substrate, a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure, the first substrate comprises a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure;

[0046] S2, forming a sacrificial layer and a protective layer on the first surface of the first substrate in sequence, the protective layer covers the sacrificial layer;

[0047] S3, etching a second surface of the first substrate to form a first cavity and a first pumping hole in the first region, and to form a second cavity in the second region, the first pumping hole exposes the sacrificial layer;

[0048] S4, bonding the second surface of the first substrate with the first surface of the second substrate, the first pumping hole and the first cavity are communicated after bonding;

[0049] Step S5, forming a plurality of second gas extraction holes in the protective layer; before bonding the second surface of the first substrate with the first surface of the second substrate, releasing part of the sacrificial layer through the first gas extraction holes to form third cavities in the sacrificial layer; or, after forming a plurality of second gas extraction holes in the protective layer, releasing part of the sacrificial layer through the second gas extraction holes to form third cavities in the sacrificial layer; the second gas extraction holes communicate with the third cavities;

[0050] Step S6, extracting gas from the first cavities through the second gas extraction holes, the third cavities and the first gas extraction holes, and filling a metal layer in the second gas extraction holes.

[0051] Hereinafter, referring to Figures 3a to 3k A method for manufacturing a MEMS device provided by the embodiment will be described in more detail, Figures 3a to 3k is Figure 2 a device schematic diagram in the method for manufacturing a MEMS device shown in the figure, Figures 3a to 3k is also a longitudinal sectional schematic diagram of a MEMS device.

[0052] According to step S1, referring to Figure 3a and Figure 3h , a first substrate 21 and a second substrate 31 are provided, a first surface of the second substrate 31 is formed with a first MEMS structure and a second MEMS structure, the first substrate 21 includes a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure.

[0053] The first substrate 21 can be only a semiconductor substrate or a wafer containing a semiconductor substrate, etc., and device structures such as transistors can be formed in the first substrate 21 as needed.

[0054] Preferably, the semiconductor substrate is a double-polished wafer, so that the structures made in the first substrate 21 have better performance.

[0055] The first MEMS structure and the second MEMS structure can each include a comb structure and a mass block.

[0056] As shown in Figure 3h , the second substrate 31 can include a semiconductor substrate 311 and a first insulating medium layer 312 covering a first surface of the semiconductor substrate 311, a conductive structure 313 connected with the semiconductor substrate 311 is formed in the first insulating medium layer 312, and the first insulating medium layer 312 exposes the conductive structure 313; device structures can also be formed in the semiconductor substrate 311 and the first insulating medium layer 312, which can include transistors, etc.

[0057] The second substrate 31 may further include a second sacrificial layer 314 and a semiconductor layer 315 covering the first insulating dielectric layer 312. The semiconductor layer 315 covers the second sacrificial layer 314. A fifth cavity 3141 is formed in the second sacrificial layer 314, and the fifth cavity 3141 exposes part of the first insulating dielectric layer 312 and part of the conductive structure 313. The comb structure and mass block in the first MEMS structure and the comb structure and mass block in the second MEMS structure are formed in the semiconductor layer 315. Release holes 3151 are formed in the comb structure, between the mass block and the comb structure, and between the mass blocks. The release holes 3151 communicate with the fifth cavity 3141. The fifth cavity 3141 is used to provide vibration space for the comb structure and the mass block.

[0058] Furthermore, the second substrate 31 may also include a second insulating dielectric layer 316 covering the second surface of the semiconductor substrate 311, so that the second surface of the semiconductor substrate 311 is insulated from other structures.

[0059] And, as Figure 3h As shown, before subsequently bonding the second surface of the first substrate 21 to the first surface of the second substrate 31, the method for manufacturing the MEMS device further includes: forming a second bonding ring 32 on the first surface of the second substrate 31. The second bonding ring 32 may be formed after the semiconductor layer 315 is formed and before the release hole 3151 is formed, and the second bonding ring 32 is formed on the semiconductor layer 315.

[0060] The step of forming the second bonding ring 32 on the first surface of the second substrate 31 may include: first, forming a metal material on the first surface of the second substrate 31 using a sputtering or evaporation process; then, forming a patterned mask layer (not shown) on the metal material; then, etching the metal material using the patterned mask layer as a mask to form the second bonding ring 32; and then, removing the patterned mask layer.

[0061] The semiconductor substrate may be made of Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs, or other III / V compound semiconductors, and may also include multilayer structures composed of these semiconductors; alternatively, the semiconductor substrate may be silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), etc. Those skilled in the art can select the appropriate substrate as needed.

[0062] The material of the semiconductor layer 315 can include Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs or other III / V compound semiconductor, and can also include a multilayer structure composed of these semiconductors, etc.

[0063] The material of the first insulating medium layer 312 and the second insulating medium layer 316 can be at least one of silicon oxide, silicon oxynitride and silicon nitride, and the first insulating medium layer 312 can be a structure stacked by at least two layers.

[0064] The material of the conductive structure 313 can be polysilicon or metal.

[0065] The material of the second sacrificial layer 314 includes but is not limited to silicon oxide.

[0066] The material of the second bonding ring 32 can include germanium, aluminum, copper, nickel or gold, etc.

[0067] According to step S2, referring to Figure 3a and Figure 3b , a first sacrificial layer 22 and a protective layer 23 are sequentially formed on the first surface of the first substrate 21, and the protective layer 23 covers the first sacrificial layer 22.

[0068] The protective layer 23 is used to protect the first sacrificial layer 22 to avoid the first sacrificial layer 22 from being corroded by cleaning process in subsequent processes.

[0069] The etching rate difference between the first sacrificial layer 22 and the protective layer 23 is large, for example, the etching selectivity ratio between the first sacrificial layer 22 and the protective layer 23 is greater than 10, so that in subsequent etching of the first sacrificial layer 22, the protective layer 23 is not etched or only a small amount of etching is performed.

[0070] The material of the first sacrificial layer 22 includes but is not limited to silicon oxide.

[0071] The material of the protective layer 23 can be silicon nitride, polysilicon or monocrystalline silicon, etc.

[0072] And, referring to Figure 3c , before etching the second surface of the first substrate 21, the manufacturing method of the MEMS device further includes forming a first bonding ring 24 on the second surface of the first substrate 21.

[0073] The step of forming the first bonding ring 24 on the second surface of the first substrate 21 can include: first, forming a metal material on the second surface of the first substrate 21 by using a sputtering or evaporation process; then, forming a patterned mask layer (not shown) on the metal material; then, etching the metal material to form the first bonding ring 24 by using the patterned mask layer as a mask; and then, removing the patterned mask layer. In this way, a pad or other structure can be formed on the second surface of the first substrate 21 at the same time as the first bonding ring 24 is formed.

[0074] The material of the first bonding ring 24 can include a metal material such as germanium, aluminum, copper, nickel, or gold.

[0075] The first surface is a front surface, and the second surface is a back surface; or the first surface is a back surface, and the second surface is a front surface.

[0076] According to step S3, referring to Figures 3d to 3f , the second surface of the first substrate 21 is etched to form a first cavity 211 and a first exhaust hole 213 in the first region, and to form a second cavity 212 in the second region, and the first exhaust hole 213 exposes the first sacrificial layer 22.

[0077] In an embodiment, the second surface of the first region can also be formed with a fourth cavity 214.

[0078] The step of forming the first cavity 211, the first exhaust hole 213, and the fourth cavity 214 in the first region, and forming the second cavity 212 in the second region can include: first, as shown in Figure 3d , etching the second surface of the first substrate 21 to form a first cavity 211 and a fourth cavity 214 in the first region, and to form a second cavity 212 in the second region; then, as shown in Figure 3f , etching the bottom wall of the fourth cavity 214 and stopping at the first sacrificial layer 22 to form a first exhaust hole 213 in the bottom wall of the fourth cavity 214.

[0079] In this way, since the etching process has a requirement for the aspect ratio of the first exhaust hole 213 formed by etching, that is, the etching process cannot be etched to form the first exhaust hole 213 with a too high aspect ratio, when the thickness of the first substrate 21 is very thick, it is preferred to first etch the second surface of the first substrate 21 to form the fourth cavity 214, and then etch the bottom wall of the fourth cavity 214 to form the first exhaust hole 213, that is, to etch through the first substrate 21 in two steps and expose the first sacrificial layer 22. It should be noted that even if the first substrate 21 is etched through in two steps, the width of the first exhaust hole 213 formed is still relatively large.

[0080] The fourth cavity 214 and the first air exhaust hole 213 are both used for air exhaust, the width of the fourth cavity 214 is greater than the width of the first air exhaust hole 213; the first cavity 211 and the second cavity 212 are respectively used for providing vibration space for the first MEMS structure and the second MEMS structure after subsequent bonding, the width and the depth of the fourth cavity 214 are both less than the first cavity 211 and the second cavity 212, the forming sequence of the fourth cavity 214, the first cavity 211 and the second cavity 212 is not limited, and the fourth cavity 214, the first cavity 211 and the second cavity 212 can be formed simultaneously or not simultaneously.

[0081] And, as Figure 3e shown, after the first cavity 211 is formed and before the first air exhaust hole 213 is formed, the manufacturing method of the MEMS device further comprises: forming a gas absorption layer 25 on the bottom wall of the first cavity 211, the gas absorption layer 25 is used for absorbing gas to improve the vacuum degree of the MEMS device. The material of the gas absorption layer 25 can be a metal material.

[0082] According to step S4, referring to Figure 3i , the second surface of the first substrate 21 is bonded with the first surface of the second substrate 31, after bonding, the fourth cavity 214 and the first air exhaust hole 213 are communicated with the first cavity 211.

[0083] And, after bonding, the first cavity 211 is aligned with the first MEMS structure, the second cavity 212 is aligned with the second MEMS structure, and the first cavity 211 and the second cavity 212 are not communicated, so that the first cavity 211 and the first MEMS structure corresponding first MEMS device and the second cavity 212 and the second MEMS structure corresponding second MEMS device are formed on the same substrate.

[0084] The bonding of the second surface of the first substrate 21 with the first surface of the second substrate 31 comprises: bonding the second surface of the first substrate 21 with the first surface of the second substrate 31 through the first bonding ring 24 and the second bonding ring 32.

[0085] The first bonding ring 24 and the second bonding ring 32 are both annular structures, the size of the first bonding ring 24 and the second bonding ring 32 can be the same or close to the same, and the first bonding ring 24 and the second bonding ring 32 can be eutectic bonding.

[0086] In the bonding, the second surface of the first substrate 21 is opposite to the first surface of the second substrate 31, the first bonding ring 24 is aligned with the second bonding ring 32, and a pressure is applied so that the first bonding ring 24 and the second bonding ring 32 are in contact and a bonding reaction occurs under a set condition to form a metal block, and the distance between the first substrate 21 and the second substrate 31 is closer. When the materials of the first bonding ring 24 and the second bonding ring 32 are different (for example, the material of the first bonding ring 24 is aluminum and the material of the second bonding ring 32 is germanium), the metal block is an alloy.

[0087] In the bonding, the vacuum control process can use the required vacuum degree of the second MEMS device corresponding to the second cavity 212, and at this time, the vacuum degree of the second MEMS device corresponding to the second cavity 212 is the same as the vacuum degree of the first MEMS device corresponding to the first cavity 211.

[0088] According to step S5, referring to Figure 3j , the protective layer 23 is etched to form a plurality of second exhaust holes 231 in the protective layer 23.

[0089] And, referring to Figure 3g , before bonding the second surface of the first substrate 21 with the first surface of the second substrate 31, part of the first sacrificial layer 22 is released through the fourth cavity 214 and the first exhaust hole 213 to form a third cavity 221 in the first sacrificial layer 22; or, after forming a plurality of second exhaust holes 231 in the protective layer 23, part of the first sacrificial layer 22 is released through the second exhaust holes 231 to form a third cavity 221 in the first sacrificial layer 22.

[0090] The second exhaust hole 231 communicates with the third cavity 221, the third cavity 221 exposes the protective layer 23, and the width of the third cavity 221 is greater than the width of the first exhaust hole 213.

[0091] Among them, the gaseous hydrofluoric acid (Vapor HF, VHF) etching process can be used to release part of the first sacrificial layer 22, that is, gaseous hydrofluoric acid is introduced into the fourth cavity 214 and the first exhaust hole 213 to etch and remove part of the first sacrificial layer 22 through the fourth cavity 214 and the first exhaust hole 213; or, gaseous hydrofluoric acid is introduced into the second exhaust hole 231 to etch and remove part of the first sacrificial layer 22 through the second exhaust hole 231.

[0092] Preferably, the first gas extraction hole 213 is staggered with the second gas extraction hole 231. Since the metal particles will fall down through the second gas extraction hole 231 when the subsequent metal layer 41 is filled into the second gas extraction hole 231, by staggering the first gas extraction hole 213 with the second gas extraction hole 231, the metal particles can be prevented from falling into the first gas extraction hole 213, thereby preventing the metal particles from falling into the device through the first gas extraction hole 213 and affecting the performance of the device.

[0093] Preferably, the metal particles will fall and accumulate in the third cavity 221 below the second gas extraction hole 231; the first gas extraction hole 213 can be aligned with the middle region of the third cavity 221, and the second gas extraction hole 231 can be aligned with the edge region of the third cavity 221, so that the metal particles fall and accumulate in the edge region of the third cavity 221.

[0094] Preferably, the width of the second gas extraction hole 231 is smaller than the width of the first gas extraction hole 213, so that the subsequent metal layer 41 can quickly fill the second gas extraction hole 231, that is, quickly realize hole sealing.

[0095] Further preferably, the width of the first gas extraction hole 213 is 10-20 μm, and the width of the second gas extraction hole 231 is 1-5 μm.

[0096] Since the etching process has a requirement for the aspect ratio of the first pumping hole 213 formed by etching, that is, the aspect ratio of the first pumping hole 213 is too high, the etching process cannot be etched to be realized, therefore, when the thickness of the first substrate 21 is very thick, the width of the first pumping hole 213 formed by etching the first substrate 21 is also larger, at this time, if the laser hole sealing process is directly used to seal the first pumping hole 213, the effect is not good or even cannot be sealed; and the special machine table used in the laser hole sealing process is expensive, and the first pumping hole 213 is sealed one by one during operation, which leads to low sealing efficiency and high cost. Therefore, the manufacturing method of the MEMS device provided by the application forms the second pumping hole 231 communicated with the first pumping hole 213 in the protection layer 23, and then fills the metal layer 41 in the second pumping hole 231 to realize sealing, so that the sealing of the pumping hole can be realized without using the laser sealing process; and compared with the sealing by the laser sealing process, the manufacturing method of the MEMS device provided by the application can solve the problem that the laser sealing process has poor sealing effect on the first pumping hole 213 with large width or even cannot be sealed, the manufacturing method of the MEMS device can realize sealing of the second pumping hole 231 with any width, and the sealing effect is better; and the conventional deposition machine table can be used to realize sealing, without using expensive special machine table, and all the second pumping holes 231 can be sealed at the same time, so that the sealing efficiency is obviously improved, and the cost is reduced.

[0097] According to step S6, referring to Figure 3k , the first cavity 211 is pumped through the second pumping hole 231, the third cavity 221 and the first pumping hole 213, so that the first MEMS device corresponding to the first cavity 211 reaches the required vacuum degree; and the metal layer 41 is filled in the second pumping hole 231 to realize sealing of the second pumping hole 231, so that the second pumping hole 231, the third cavity 221, the first pumping hole 213, the fourth cavity 214 and the first cavity 211 are sealed.

[0098] The metal layer 41 can be deposited in the second pumping hole 231 by a physical vapor deposition process or an evaporation process, etc. Before the physical vapor deposition or evaporation process is performed, the chamber needs to be pumped to vacuum. In this step, since the first cavity 211 is in communication with the outside through the second pumping hole 231, the third cavity 221 and the first pumping hole 213, the gas in the first cavity 211 can be pumped out during the vacuum pumping process, so that the vacuum degree of the first cavity 211 reaches the required degree of vacuum for the first MEMS device. The second cavity 212 is not in communication with the outside, so that the vacuum pumping process does not affect the vacuum degree of the second cavity 212, and the vacuum degree of the second cavity 212 remains the same as that during the bonding process. Thus, the first MEMS device and the second MEMS device formed on the same substrate can have different vacuum degrees. The process of depositing the metal layer 41 is also performed in the same vacuum chamber, so that after the metal layer 41 is deposited, the first cavity 211 still maintains its required vacuum degree.

[0099] In addition, the process temperature range for depositing the metal layer 41 in the second pumping hole 231 by the physical vapor deposition process is 400-500°C, and the process temperature for depositing the metal layer 41 in the second pumping hole 231 by the evaporation process is room temperature. Compared with the high temperature of 700-800°C for depositing the insulating material in the second pumping hole 231 by the chemical vapor deposition process, the process temperature for depositing the metal layer 41 by the physical vapor deposition process and the evaporation process is lower, so that the metal block formed by the bonding reaction between the first bonding ring 24 and the second bonding ring 32 can be prevented from being melted by high temperature during the hole sealing process, thereby avoiding abnormal bonding.

[0100] The first MEMS device can be a gyroscope, and the second MEMS device can be an accelerometer. The first MEMS structure can include a comb structure and a mass block of the gyroscope, and the second MEMS structure can include a comb structure and a mass block of the accelerometer. Alternatively, the first MEMS device can be an accelerometer, and the second MEMS device can be a gyroscope. The first MEMS structure can include a comb structure and a mass block of the accelerometer, and the second MEMS structure can include a comb structure and a mass block of the gyroscope.

[0101] From the above, the manufacturing method of the MEMS device of the present application, by sequentially forming a first sacrificial layer and a protective layer covering the first surface of the first substrate; etching the second surface of the first substrate to form a first cavity and a first pumping hole in the first region, and a second cavity in the second region, the first pumping hole exposes the first sacrificial layer; and after bonding the second surface of the first substrate with the first surface of the second substrate, a plurality of second pumping holes are formed in the protective layer; and a third cavity is formed in the first sacrificial layer which communicates with the second pumping hole and the first pumping hole; through the second pumping hole, the third cavity and the first pumping hole, the first cavity is pumped, and a metal layer is filled in the second pumping hole, so that the sealing of the pumping hole can be realized without using the laser sealing process, at the same time, the problem of sealing large size pumping hole can be solved, and the cost is reduced.

[0102] An embodiment of the present application provides a MEMS device, comprising: a second substrate, a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure; a first substrate, a second surface of the first substrate is bonded on the first surface of the second substrate; the first substrate comprises a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure, a second surface of the first region is formed with a first cavity and a first pumping hole, and a second surface of the second region is formed with a second cavity; a first surface of the first substrate is covered with a sacrificial layer and a protective layer, the protective layer covers the sacrificial layer, a third cavity is formed in the sacrificial layer, and a plurality of second pumping holes are formed in the protective layer, the first pumping hole respectively communicates with the first cavity and the third cavity, the third cavity communicates with the second pumping hole; the second pumping hole is filled with a metal layer.

[0103] Reference will be made to the drawings Figure 3k The MEMS device of the present embodiment will be described in more detail, Figure 3k is a schematic view of a longitudinal section of the MEMS device.

[0104] The first surface of the second substrate 31 is formed with a first MEMS structure and a second MEMS structure.

[0105] The first MEMS structure and the second MEMS structure can each comprise a comb structure and a mass block.

[0106] The second substrate 31 can include a semiconductor substrate 311 and a first insulating medium layer 312 covering a first surface of the semiconductor substrate 311, the first insulating medium layer 312 having a conductive structure 313 connected with the semiconductor substrate 311 formed therein, and the first insulating medium layer 312 exposing the conductive structure 313; the semiconductor substrate 311 and the first insulating medium layer 312 can further have a device structure formed therein, which can include a transistor and the like.

[0107] The second substrate 31 can further include a second sacrificial layer 314 and a semiconductor layer 315 covering the first insulating medium layer 312, the semiconductor layer 315 covering the second sacrificial layer 314, the second sacrificial layer 314 having a fifth cavity 3141 formed therein, the fifth cavity 3141 exposing part of the first insulating medium layer 312 and part of the conductive structure 313; the semiconductor layer 315 having the comb structure and the mass in the first MEMS structure and the comb structure and the mass in the second MEMS structure formed therein, and the release holes 3151 formed in the comb structure, between the mass and the comb structure, and between the masses, the release holes 3151 communicating with the fifth cavity 3141, and the fifth cavity 3141 being used to provide vibration space for the comb structure and the mass.

[0108] In addition, the second substrate 31 can further include a second insulating medium layer 316 covering a second surface of the semiconductor substrate 311, so that the second surface of the semiconductor substrate 311 is insulated from other structures.

[0109] The second surface of the first substrate 21 is bonded on the first surface of the second substrate 31; the first substrate 21 includes a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure.

[0110] The first substrate 21 can be only a semiconductor substrate or a wafer containing a semiconductor substrate, and the first substrate 21 can have a device structure such as a transistor formed therein as needed.

[0111] Preferably, the semiconductor substrate is a double-polished wafer, so that the performance of the structure made in the first substrate 21 is better.

[0112] The material of the semiconductor substrate can include Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs or other III / V compound semiconductor, and can also include a multilayer structure composed of these semiconductors, etc. Alternatively, the semiconductor substrate can be silicon-on-insulator (SOI), stacked silicon-on-insulator (SSOI), stacked silicon germanium-on-insulator (S-SiGeOI), silicon germanium-on-insulator (SiGeOI), germanium-on-insulator (GeOI), etc. Those skilled in the art can select as needed.

[0113] The material of the semiconductor layer 315 can include Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs or other III / V compound semiconductor, and can also include a multilayer structure composed of these semiconductors, etc.

[0114] The material of the first insulating medium layer 312 and the second insulating medium layer 316 can be at least one of silicon oxide, silicon oxynitride and silicon nitride, and the first insulating medium layer 312 can be a structure stacked by at least two layers.

[0115] The material of the conductive structure 313 can be polysilicon or metal.

[0116] The material of the second sacrificial layer 314 includes but is not limited to silicon oxide.

[0117] The second surface of the first region is formed with a first cavity 211 and a first air hole 213, and the second surface of the second region is formed with a second cavity 212.

[0118] The first cavity 211 is aligned with the first MEMS structure, and the second cavity 212 is aligned with the second MEMS structure. The first cavity 211 and the second cavity 212 are respectively used to provide vibration space for the first MEMS structure and the second MEMS structure. The first cavity 211 and the second cavity 212 are not connected, so that the first cavity 211 and the first MEMS structure correspond to a first MEMS device, and the second cavity 212 and the second MEMS structure correspond to a second MEMS device, which are formed on the same substrate.

[0119] The first surface of the first substrate 21 is covered with a first sacrificial layer 22 and a protective layer 23. The protective layer 23 covers the first sacrificial layer 22. The first sacrificial layer 22 is formed with a third cavity 221, and the protective layer 23 is formed with a plurality of second air holes (i.e. Figure 3jThe first air exhaust hole 213 is in communication with the first cavity 211 and the third cavity 221, and the third cavity 221 is in communication with the second air exhaust hole 231.

[0120] The first surface is a front surface, and the second surface is a back surface, or the first surface is a back surface, and the second surface is a front surface.

[0121] The protective layer 23 is used to protect the first sacrificial layer 22, so as to avoid the first sacrificial layer 22 from being corroded by a cleaning process or the like.

[0122] The etching rate of the first sacrificial layer 22 and the protective layer 23 is different, for example, the etching selection ratio of the first sacrificial layer 22 and the protective layer 23 is greater than 10, so that when the first sacrificial layer 22 is etched to form the third cavity 221, the protective layer 23 is not etched or is only slightly etched.

[0123] The material of the first sacrificial layer 22 includes but is not limited to silicon oxide.

[0124] The material of the protective layer 23 can be silicon nitride, polysilicon or monocrystalline silicon, etc.

[0125] The second surface of the first region can further form a fourth cavity 214 in communication with the first air exhaust hole 213, the first air exhaust hole 213 is located between the third cavity 221 and the fourth cavity 214, and the fourth cavity 214 is in communication with the first cavity 211.

[0126] The width of the fourth cavity 214 is greater than the width of the first air exhaust hole 213, and the width and depth of the fourth cavity 214 are less than those of the first cavity 211 and the second cavity 212.

[0127] The MEMS device can further include a gas absorption layer 25 formed on the bottom wall of the first cavity 211, and the gas absorption layer 25 is used to absorb gas to improve the vacuum degree of the MEMS device. The material of the gas absorption layer 25 can be a metal material.

[0128] Preferably, the first air extraction hole 213 is staggered with the second air extraction hole 231. When the metal layer 41 is filled into the second air extraction hole 231, metal particles will fall down through the second air extraction hole 231. By staggering the first air extraction hole 213 with the second air extraction hole 231, the metal particles can be prevented from falling into the first air extraction hole 213, thereby preventing the metal particles from falling into the device through the first air extraction hole 213 and affecting the performance of the device.

[0129] Preferably, the metal particles will fall and accumulate in the third cavity 221 below the second air extraction hole 231; the first air extraction hole 213 can be aligned with the middle region of the third cavity 221, and the second air extraction hole 231 can be aligned with the edge region of the third cavity 221, so that the metal particles fall and accumulate in the edge region of the third cavity 221.

[0130] Preferably, the width of the second air extraction hole 231 is smaller than the width of the first air extraction hole 213, so that the metal layer 41 can quickly fill the second air extraction hole 231, i.e. quickly realize hole sealing.

[0131] Further preferably, the width of the first air extraction hole 213 is 10-20 μm, and the width of the second air extraction hole 231 is 1-5 μm.

[0132] Since the first cavity 211 is in communication with the second air extraction hole 231, the third cavity 221 and the first air extraction hole 213, the first cavity 211 can be evacuated through the second air extraction hole 231, the third cavity 221 and the first air extraction hole 213, thereby enabling the first MEMS device corresponding to the first cavity 211 to reach the required vacuum degree; and by filling the metal layer 41 into the second air extraction hole 231, the hole sealing of the second air extraction hole 231 can be realized, thereby sealing the second air extraction hole 231, the third cavity 221, the first air extraction hole 213, the fourth cavity 214 and the first cavity 211.

[0133] The MEMS device further comprises:

[0134] A first bonding ring 24 is formed on the second surface of the first substrate 21.

[0135] A second bonding ring 32 is formed on the first surface of the second substrate 31, and the second surface of the first substrate 21 and the first surface of the second substrate 31 are bonded by the first bonding ring 24 and the second bonding ring 32.

[0136] The material of the second bonding ring 32 can include metal materials such as germanium, aluminum, copper, nickel or gold.

[0137] The first bonding ring 24 and the second bonding ring 32 are both ring structures, the sizes of the first bonding ring 24 and the second bonding ring 32 can be the same or close to the same, and the first bonding ring 24 and the second bonding ring 32 can be eutectic bonding.

[0138] In the bonding process, the second surface of the first substrate 21 is opposite to the first surface of the second substrate 31, the first bonding ring 24 and the second bonding ring 32 are aligned, and a pressure is applied so that the first bonding ring 24 and the second bonding ring 32 are in contact and a bonding reaction occurs under a certain condition to form a metal block, and the distance between the first substrate 21 and the second substrate 31 is closer. When the materials of the first bonding ring 24 and the second bonding ring 32 are different (for example, the material of the first bonding ring 24 is aluminum and the material of the second bonding ring 32 is germanium), the metal block is an alloy.

[0139] In the bonding process, the required vacuum degree of the second MEMS device corresponding to the second cavity 212 can be used, and at this time, the vacuum degree of the second MEMS device corresponding to the second cavity 212 is the same as the vacuum degree of the first MEMS device corresponding to the first cavity 211.

[0140] Since the first cavity 211 is in communication with the outside through the second exhaust hole 231, the third cavity 221 and the first exhaust hole 213, the gas in the first cavity 211 can be extracted, and the vacuum degree of the first cavity 211 reaches the required requirement of the first MEMS device; and the second cavity 212 is not in communication with the outside, so that the vacuum degree of the second cavity 212 is not affected when the first cavity 211 is evacuated, and the vacuum degree of the second cavity 212 remains the same as that in the bonding process. Thus, the first MEMS device and the second MEMS device formed on the same substrate can have different vacuum degrees. Moreover, the process of filling the metal layer 41 is also carried out in the same vacuum chamber, so that after the metal layer 41 is filled, the first cavity 211 still maintains its required vacuum degree.

[0141] The first MEMS device can be a gyroscope, and the second MEMS device can be an accelerometer. The first MEMS structure can include a comb structure and a mass block of the gyroscope, and the second MEMS structure can include a comb structure and a mass block of the accelerometer. Alternatively, the first MEMS device can be an accelerometer, and the second MEMS device can be a gyroscope. The first MEMS structure can include a comb structure and a mass block of the accelerometer, and the second MEMS structure can include a comb structure and a mass block of the gyroscope.

[0142] Since the etching process has a requirement for the aspect ratio of the first pumping hole 213 formed by etching, that is, the aspect ratio of the first pumping hole 213 is too high, the etching process cannot be etched to be realized, therefore, when the thickness of the first substrate 21 is very thick, the width of the first pumping hole 213 formed by etching the first substrate 21 is also large, at this time, if the laser hole sealing process is directly used to seal the first pumping hole 213, the effect is not good or even cannot be sealed. Moreover, the special machine table used in the laser hole sealing process is expensive, and the first pumping hole 213 is sealed one by one during operation, which leads to low sealing efficiency and high cost. Therefore, in the MEMS device provided by the application, the second pumping hole 231 communicating with the first pumping hole 213 is formed in the protective layer 23, and the metal layer 41 is filled in the second pumping hole 231 to realize hole sealing, so that the laser hole sealing process is not needed to realize the sealing of the pumping hole. Compared with the laser hole sealing process, the MEMS device provided by the application can solve the problem that the laser hole sealing process has a poor sealing effect on the first pumping hole 213 with a large width or even cannot seal the hole. The second pumping hole 231 with any width in the MEMS device can realize hole sealing, and the sealing effect is better. The conventional deposition machine table can be used to realize hole sealing, without using expensive special machine tables, and all the second pumping holes 231 can be sealed at the same time, so that the sealing efficiency is obviously improved, and the cost is reduced.

[0143] From the above, it can be seen that the MEMS device of the application comprises: a second substrate, a first surface of the second substrate forms a first MEMS structure and a second MEMS structure; a first substrate, a second surface of the first substrate is bonded to the first surface of the second substrate; the first substrate comprises a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure, a second surface of the first region forms a first cavity and a first pumping hole, and a second surface of the second region forms a second cavity; a first surface of the first substrate is covered with a first sacrificial layer and a protective layer, the protective layer covers the first sacrificial layer, a third cavity is formed in the first sacrificial layer, and a plurality of second pumping holes are formed in the protective layer, the first pumping hole respectively communicates with the first cavity and the third cavity, and the third cavity communicates with the second pumping hole; the second pumping hole is filled with a metal layer, so that the laser hole sealing process is not needed to realize the sealing of the pumping hole, the problem of sealing the large-size pumping hole is solved, and the cost is reduced.

[0144] The above description is only the description of the preferred embodiments of the present application, and is not any limitation on the scope of the present application. Any change and modification made by the person skilled in the art according to the above disclosure is within the protection scope of the claims.

Claims

1. A method for manufacturing a MEMS device, characterized in that, include: A first substrate and a second substrate are provided, wherein a first MEMS structure and a second MEMS structure are formed on a first surface of the second substrate, and the first substrate includes a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure. A sacrificial layer and a protective layer are sequentially formed on the first surface of the first substrate, wherein the protective layer covers the sacrificial layer; The second surface of the first substrate is etched to form a first cavity and a first vent hole in the first region, and a second cavity in the second region, wherein the first vent hole exposes the sacrificial layer. The second surface of the first substrate is bonded to the first surface of the second substrate, and the first vent hole after bonding is connected to the first cavity. Multiple second vent holes are formed in the protective layer; Before bonding the second surface of the first substrate to the first surface of the second substrate, a portion of the sacrificial layer is released through the first vent hole to form a third cavity in the sacrificial layer; or, after forming a plurality of second vent holes in the protective layer, a portion of the sacrificial layer is released through the second vent holes to form a third cavity in the sacrificial layer. The second air extraction port is connected to the third cavity; The first cavity is evacuated through the second evacuation port, the third cavity, and the first evacuation port, and a metal layer is filled into the second evacuation port.

2. The method for manufacturing a MEMS device as described in claim 1, characterized in that, The positions of the first air extraction port and the second air extraction port are offset.

3. The method for manufacturing a MEMS device as described in claim 1, characterized in that, The width of the second air extraction hole is smaller than the width of the first air extraction hole.

4. The method for manufacturing a MEMS device as described in claim 3, characterized in that, The width of the first air extraction hole is 10μm to 20μm, and the width of the second air extraction hole is 1μm to 5μm.

5. The method for manufacturing a MEMS device as described in claim 1, characterized in that, The second surface of the first region also has a fourth cavity formed therein; the steps of forming the first cavity, the first vent, and the fourth cavity in the first region, and forming the second cavity in the second region, include: The second surface of the first substrate is etched to form a first cavity and a fourth cavity in the first region, and a second cavity in the second region; The bottom wall of the fourth cavity is etched to form a first vent hole in the bottom wall of the fourth cavity.

6. The method for manufacturing a MEMS device as described in claim 1, characterized in that, Before etching the second surface of the first substrate, the method for manufacturing the MEMS device further includes: A first bonding ring is formed on the second surface of the first substrate; Before bonding the second surface of the first substrate to the first surface of the second substrate, the method for manufacturing the MEMS device further includes: A second bonding ring is formed on the first surface of the second substrate; The step of bonding the second surface of the first substrate to the first surface of the second substrate includes: bonding the second surface of the first substrate to the first surface of the second substrate through the first bonding ring and the second bonding ring.

7. The method for manufacturing a MEMS device as described in claim 1, characterized in that, The first MEMS structure includes a comb structure for a gyroscope, and the second MEMS structure includes a comb structure for an accelerometer.

8. A MEMS device, characterized in that, include: The second substrate has a first MEMS structure and a second MEMS structure formed on its first surface. A first substrate, wherein a second surface of the first substrate is bonded to a first surface of a second substrate; the first substrate includes a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure, a first cavity and a first vent hole are formed on the second surface of the first region, and a second cavity is formed on the second surface of the second region; a sacrificial layer and a protective layer are covered on the first surface of the first substrate, the protective layer covers the sacrificial layer, a third cavity is formed in the sacrificial layer, and a plurality of second vent holes are formed in the protective layer, the first vent holes are respectively connected to the first cavity and the third cavity, and the third cavity is connected to the second vent holes; a metal layer is filled in the second vent holes.

9. The MEMS device as described in claim 8, characterized in that, The positions of the first air extraction port and the second air extraction port are offset.

10. The MEMS device as described in claim 8, characterized in that, The width of the second air extraction hole is smaller than the width of the first air extraction hole.

11. The MEMS device as claimed in claim 10, characterized in that, The width of the first air extraction hole is 10μm to 20μm, and the width of the second air extraction hole is 1μm to 5μm.

12. The MEMS device as described in claim 8, characterized in that, The second surface of the first region also forms a fourth cavity that communicates with the first air extraction hole, and the first air extraction hole is located between the third cavity and the fourth cavity.

13. The MEMS device as described in claim 8, characterized in that, The MEMS device also includes: A first bonding ring is formed on the second surface of the first substrate; A second bonding ring is formed on the first surface of the second substrate, and the second surface of the first substrate is bonded to the first surface of the second substrate through the first bonding ring and the second bonding ring.

14. The MEMS device as described in claim 8, characterized in that, The first MEMS structure includes a comb structure for a gyroscope, and the second MEMS structure includes a comb structure for an accelerometer.

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