Method for manufacturing micro-electromechanical system device, micro-electromechanical system device and electronic device

Abstract

Disclosed are a method for manufacturing a micro-electromechanical system device, a micro-electromechanical system device, and an electronic device. The micro-electromechanical system device includes a thin-film type micro-electromechanical system device layer, and the manufacturing method includes: forming a sacrificial layer on a micro-electromechanical system substrate; forming a micro-electromechanical system device layer on the sacrificial layer; temporarily bonding a carrier layer to the micro-electromechanical system device layer via a temporary bonding layer, wherein the carrier layer is transparent and rigid; releasing the micro-electromechanical system device layer by processing the sacrificial layer; debonding the carrier layer from the released micro-electromechanical system device layer by exposure; and removing the temporary bonding layer.

Description

Technical Field

[0001] The present application belongs to the technical field of micro-electromechanical system devices, and in particular, relates to a method for manufacturing a micro-electromechanical system device, a micro-electromechanical system device, and an electronic device. Background Art

[0002] Micro-Electro-Mechanical System (MEMS), also known as micro-electro-mechanical system, microsystem, micromachine, etc., refers to high-tech devices with a size of several millimeters or even smaller.

[0003] During the manufacturing process of a MEMS device, the MEMS layer of the MEMS device is released by etching the sacrificial layer. MEMS devices such as MEMS microphones, pressure sensors, and FBARs typically have a thin-film type MEMS device layer. The thin-film type MEMS device layer has a large aspect ratio (i.e., the ratio of surface size to thickness). Therefore, when the patterned MEMS device layer is released from the unpatterned sacrificial layer (usually silicon dioxide), the MEMS device layer experiences an unbalanced stress gradient. Therefore, upon release (removal of the sacrificial layer), the MEMS device layer may suffer from stress concentration or mechanical damage.

[0004] Such a MEMS device having a thin film type MEMS device layer may be, for example, a MEMS microphone, a thin film bulk acoustic wave resonator, a piezoelectric pressure sensor, a comb-driven capacitive sensor (accelerometer, gyroscope, etc.), a spintronic MEMS sensor, etc. Summary of the invention

[0005] The present application aims to provide a new technical solution for a micro-electromechanical system device.

[0006] According to a first aspect of the present disclosure, a method for manufacturing a micro-electromechanical system device is provided, wherein the micro-electromechanical system device includes a thin-film type micro-electromechanical system device layer, and the manufacturing method includes: forming a sacrificial layer on a micro-electromechanical system substrate; forming a micro-electromechanical system device layer on the sacrificial layer; temporarily bonding a carrier layer to the micro-electromechanical system device layer via a temporary bonding layer, wherein the carrier layer is transparent and rigid; releasing the micro-electromechanical system device layer by processing the sacrificial layer; debonding the carrier layer from the released micro-electromechanical system device layer by exposure; and removing the temporary bonding layer.

[0007] According to a second aspect of the present disclosure, there is provided a micro-electromechanical system device manufactured using the above manufacturing method.

[0008] According to a third aspect of the present disclosure, an electronic device is provided, comprising the micro-electromechanical system device described above.

[0009] In the embodiments herein, the support function of the carrier layer is utilized to prevent the stress during release from damaging the MEMS device layer, thereby ensuring the performance and / or yield of the MEMS device.

[0010] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0012] Figure 1 A schematic diagram of the structure of the MEMS device when released is shown.

[0013] Figure 2 Schematic diagram showing stress damage of a MEMS device during release.

[0014] Figure 3-7 is a schematic flow chart of a method for manufacturing a MEMS device according to an embodiment.

[0015] Figure 8 is a schematic diagram of an electronic device according to an embodiment.

[0016] Reference numerals:

[0017] 101. substrate; 102. sacrificial layer; 103. micro-electromechanical system device layer; 104. passivation layer; 105. pad and interconnect structure layer; 106. temporary protection layer; 107 back hole; 108. sensing layer; 1. substrate; 2. sacrificial layer; 3. micro-electromechanical system device layer; 4. temporary bonding layer; 5. carrier layer; 6. back hole; 200. electronic device; 201. micro-electromechanical system device. DETAILED DESCRIPTION

[0018] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0019] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0020] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0021] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0022] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0023] Figure 1 A schematic diagram of the structure of the MEMS device when released is shown. Figure 2 Schematic diagram showing the stress of a MEMS device during release.

[0024] Figure 1 Figure 2 shows a schematic diagram of the structure of the MEMS device before release. Figure 1 As shown, the MEMS device includes a substrate 101, a sacrificial layer 102, a MEMS device layer 103, a passivation layer 104, a pad and interconnection structure layer 105, and a sensing layer 108. Figure 1 In the embodiment, a back hole 107 is formed in the substrate 101. Optionally, a temporary protection layer 106 is formed on the MEMS device layer 103. The material of the temporary protection layer 106 is usually photoresist.

[0025] Substrate 101 is, for example, a thin MEMS silicon substrate. The material of sacrificial layer 102 is usually silicon dioxide, which has high compressive resistance and can usually withstand a pressure of more than 300 MPa. MEMS device layer 103 is the mechanical structure layer of the MEMS device, such as a diaphragm, a cantilever beam, etc. The material of MEMS device layer 103 can be silicon or polysilicon. Here, MEMS device layer 103 is a thin film type with a large aspect ratio. The thin film type MEMS device layer 103 can be damaged by the stress of the sacrificial layer 102. The material of passivation layer 104 can be SiN x The material of the pad and interconnect structure layer 105 can be Cr / Ni / Au, etc. The sensing layer 108 is, for example, a unit for sensing mechanical changes. Figure 1 In FIG. 1 , the sensing layer 108 is shown as a magnetic source and a magnetic resistor. The sensing layer 108 may also be other sensing structures.

[0026] Figure 2The case where the MEMS device layer 103 is broken during release is shown. For example, the MEMS device layer 103 is patterned, while the sacrificial layer below it is not patterned. A back hole 107 is formed in the silicon substrate by front-to-back alignment lithography and deep reactive ion etching (DRIE). The back hole 107 stops at the sacrificial layer. The MEMS device layer 103 is usually designed to have low tensile stress. The sacrificial layer of silicon dioxide usually has high compressive stress and is thicker (e.g., 0.5 to 2 microns), which will produce a large stress gradient. Therefore, if Figure 2 As shown, the MEMS device layer 103 is easily broken under such non-uniform stress. Figure 1 The protective layer in the embodiment is usually not rigid, and therefore, it cannot completely protect the thin film type MEMS device layer 103 .

[0027] The inventor of the present invention proposes a technical solution of using a wafer support system to assist in the release. Figure 3-8 Various embodiments are described.

[0028] Figure 3-7 A schematic flow chart of a method for manufacturing a micro-electromechanical system device according to an embodiment is shown.

[0029] like Figure 3 As shown, a sacrificial layer 2 is formed on a MEMS substrate 1 , and a MEMS device layer 3 is formed on the sacrificial layer 2 .

[0030] The material of the MEMS substrate 1 may be silicon, for example, and its thickness ranges from 380 to 750 microns. The sacrificial layer 2 may be silicon dioxide or buried oxide, for example. The MEMS device layer 3 may be a MEMS mechanical layer, for example, and its material may be silicon, polysilicon or other materials constituting a mechanical structure.

[0031] In addition, Figure 1 Similarly, the MEMS device layer 3 may also include a passivation layer, a pad and interconnection structure layer, and a sensing layer, and their descriptions will not be repeated here.

[0032] Next, the carrier layer 5 is temporarily bonded to the MEMS device layer 3 via the temporary bonding layer 4. The carrier layer 5 is transparent and rigid. For example, the thickness of the carrier layer 5 is 300-700 micrometers. The carrier layer 5 may be a support wafer.

[0033] Those skilled in the art will understand that, here, "transparent" means that the carrier layer 5 is transparent to the light used for debonding. "Rigid" means that when the sacrificial layer 2 is removed, the carrier layer 5 is sufficient to support the MEMS device layer 3 to resist the stress during release.

[0034] The material of the temporary bonding layer 4 may be, for example, photoresist, adhesive, etc. The temperature of temporary bonding through the temporary bonding layer 4 is preferably less than 150 degrees. For example, the thickness of the temporary bonding layer 4 is between 1 micron and 10 microns, preferably, between 2 microns and 5 microns, so that the problem of temperature dissipation caused by thermal insulation can be avoided.

[0035] Figure 4 and Figure 5 The process of releasing the MEMS device layer 3 by processing the sacrificial layer 2 is shown.

[0036] like Figure 4 As shown, the substrate 1 is processed to form a back hole 6. The substrate 1 can be thinned to a thickness of 50 microns to 250 microns by back grinding. If necessary (for example, the thickness of the substrate 1 to be formed is less than 100 microns), the substrate 1 can also be polished. Next, deep reactive ion etching DRIE can be used for patterning and etching to form the back hole 6. At this stage, the back hole 6 stops at the sacrificial layer 2. The material of the sacrificial layer 2 can be silicon dioxide, and its thickness can be 0.5 microns to 2 microns. At this point, the carrier layer 5 stably supports the MEMS device layer 3, so there is no additional stress concentration or damage in the MEMS device layer 3.

[0037] like Figure 5 As shown, the MEMS device layer 3 is released. The sacrificial layer 2 is etched by reactive ion etching RIE or wet etching (for example, using hydrofluoric acid HF or buffered oxide etchant BOE) to release the MEMS device layer 3. Since the MEMS device layer 3 with a low stress level is supported by a rigid carrier layer 5 (or carrier wafer), the sacrificial layer with a high stress level can be safely removed, while reducing the possibility of damaging the MEMS device layer 3.

[0038] Figure 6 FIG. 2 shows a process of debonding the carrier layer 5 from the released MEMS device layer 3 by exposure. Figure 6 As shown by the arrow in , light for debonding, such as laser or ultraviolet light, is irradiated from the carrier layer 5 side. Due to the irradiation of light, debonding occurs at the interface between the carrier layer 5 and the temporary bonding layer 4, and the carrier layer 5 and the temporary bonding layer 4 are separated.

[0039] Here, the temporary bonding layer 4 is softer than the carrier layer 5 , so during exposure, the temporary bonding layer 4 can act as a stress buffer layer between the carrier layer 5 and the MEMS device layer 3 , thereby avoiding damage to the MEMS device layer 3 during debonding.

[0040] After debonding, the carrier layer 5 can be easily removed mechanically.

[0041] like Figure 7 As shown, the temporary bonding layer 4 is removed. For example, the bonding layer 4 can be stripped by oxygen plasma or solvents / chemical agents.

[0042] The MEMS device formed by the above-described method can form a lossless MEMS structure or a low-stress / controllable-stress MEMS structure on a thinner MEMS substrate. This is very advantageous for high-performance MEMS devices, for example, it is advantageous for high-performance microphones. In addition, this can improve the yield of the MEMS device. Compared with the previous MEMS device, under the same conditions, in the MEMS device formed by the method in the embodiment here, the MEMS device layer can have lower stress. In addition, due to different processes, for example, here, the temporary bonding layer is removed after removing the carrier layer, so the MEMS device here is different from the previous MEMS device.

[0043] Figure 8 Schematic diagram of an electronic device according to an embodiment disclosed herein is shown. Figure 8 As shown, the electronic device 200 may include a MEMS device 201, and the MEMS device 201 may be a MEMS device formed by the processes 3 to 7. The electronic device 200 may be a mobile phone, a tablet computer, a wearable device, etc. The MEMS magnetic sensor 201 may be a microphone, a pressure sensor, an inertial sensor, etc.

[0044] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration rather than for limiting the scope of the disclosure herein.

Claims

1. A method for manufacturing a micro-electromechanical system device, wherein: The MEMS device includes a thin-film MEMS device layer, and the manufacturing method includes: forming a sacrificial layer on a MEMS substrate; forming a MEMS device layer on the sacrificial layer; Temporarily bonding the carrier layer to the MEMS device layer via the temporary bonding layer, wherein the carrier layer is transparent and rigid; releasing the MEMS device layer by processing the sacrificial layer; debonding the carrier layer from the released MEMS device layer by exposure; and Remove the temporary bonding layer.

2. The manufacturing method according to claim 1, wherein: The carrier layer is a carrier wafer.

3. The manufacturing method according to claim 1, wherein: The sacrificial layer is a silicon dioxide layer or a buried oxide layer, and the thickness of the sacrificial layer ranges from 0.5 micrometers to 2 micrometers.

4. The manufacturing method according to claim 1, wherein: The curing temperature of the temporary bonding layer is less than or equal to 150°C.

5. The manufacturing method according to claim 1, wherein: The thickness of the temporary bonding layer is in the range of 1 μm to 10 μm or 2 μm to 5 μm.

6. The manufacturing method according to claim 1, further comprising: Before releasing the MEMS device layer, a back hole is formed in the MEMS substrate at a position opposite to the MEMS device layer.

7. The manufacturing method according to claim 1, further comprising: The MEMS substrate is processed so that its thickness is less than or equal to 250 micrometers or less than or equal to 100 micrometers.

8. The manufacturing method according to claim 1, wherein: The MEMS device is a MEMS piezoelectric sensor.

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