MEMS device with two independent cavities

Abstract

The utility model provides an MEMS (Micro Electro Mechanical System) device with two independent cavities. The MEMS device includes: an MEMS wafer; the cover body wafer is bonded with the MEMS wafer, and a sealed first cavity and a sealed second cavity are formed between the MEMS wafer and the cover body wafer; and the gas release material layer is formed on the MEMS wafer or / and the cover body wafer, the gas release material layer is exposed in the first cavity, and the gas release material layer releases gas to the first cavity in the bonding process of the MEMS wafer and the cover body wafer or when the gas release material layer is heated so as to change the pressure in the first cavity. Therefore, two cavities with different pressures can be more conveniently formed on the same chip.

Description

Technical Field

[0001] The utility model relates to the field of MEMS (Micro-Electro-Mechanical System) devices, and particularly to a MEMS device with two independent cavities.

Background Art

[0002] MEMS capacitive accelerometers are widely used in consumer electronics, the Internet of Things, and industrial measurement fields due to their small size, low cost, and excellent performance. With the increasingly fierce competition in consumer electronics, new requirements for cost and integration have been put forward. To achieve this goal, current 6-axis products (3-axis accelerometer + 3-axis gyroscope) have changed from the original method where the accelerometer and gyroscope are located on two independent chips to the method of fabricating the gyroscope and accelerometer on the same chip. During this process, a pressure problem will be encountered, that is, the cavities of the accelerometer and the gyroscope require different pressures. The accelerometer needs a relatively high pressure in its cavity to increase air damping, usually about 400 mBar, to improve the reliability of the device in an impact environment. The gyroscope, on the other hand, needs a relatively low pressure in its cavity, usually <5 mBar, the lower the better, preferably a vacuum environment. When integrating the accelerometer and the gyroscope on the same chip, since the cavities of the accelerometer and the gyroscope are formed simultaneously, the internal pressure increases and decreases simultaneously. How to control the pressures of the two cavities is a problem encountered in the current process.

[0003] In addition, two independent cavities with different pressures are also used in other MEMS applications, and the same problem will be encountered at this time.

[0004] Therefore, it is urgent to propose a new technical solution to solve the above problems.

Summary of the Utility Model

[0005] One of the purposes of the utility model is to provide a MEMS device with two independent cavities, which can more conveniently form two cavities with different pressures on the same chip.

[0006] To solve the above problems, according to one aspect of the utility model, a MEMS device is proposed, which includes: a MEMS wafer; a cover wafer bonded to the MEMS wafer, wherein a sealed first cavity and a second cavity are formed between the MEMS wafer and the cover wafer; a gas release material layer formed on the MEMS wafer or / and the cover wafer, the gas release material layer is exposed to the first cavity, and the gas release material layer releases gas into the first cavity during the bonding process of the MEMS wafer and the cover wafer or when heated to change the pressure in the first cavity.

[0007] Compared with the prior art, during the bonding process or when heated, the gas release material layer exposed to the first cavity releases gas into the first cavity to change the pressure inside the first cavity in the present utility model.

Description of the Drawings

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0009] Figure 1 It is a schematic structural diagram of the cover (CAP) wafer of the MEMS device in the present utility model;

[0010] Figure 2 It is a schematic structural diagram of the MEMS wafer of the MEMS device in the present utility model;

[0011] Figure 3 It is a schematic structural diagram of the MEMS device in the present utility model;

[0012] Figure 4 It is a schematic flowchart of the manufacturing method of the MEMS device in the present utility model.

Detailed Embodiments

[0013] To make the above objects, features, and advantages of the present utility model more obvious and understandable, the present utility model will be further described in detail below with reference to the drawings and specific embodiments.

[0014] As used herein, the term "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present utility model. The phrase "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments. Unless otherwise specified, the terms indicating electrical connection such as "connected", "coupled", and "joined" herein all mean directly or indirectly electrically connected.

[0015] In the present utility model, unless otherwise clearly defined and limited, terms such as "connected", "coupled", and "joined" should be understood in a broad sense; for example, it can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0016] The present utility model provides a MEMS device with two independent cavities, which can more conveniently form two cavities with different pressures on the same chip.

[0017] Figure 1 Schematic diagram of the cover wafer of the MEMS device in the present utility model Figure 2 Schematic diagram of the MEMS wafer of the MEMS device in the present utility model Figure 3 Schematic diagram of the MEMS device in the present utility model. As Figure 3 shown, the MEMS device includes a MEMS wafer 110 and a cover wafer 120 bonded to the MEMS wafer 110.

[0018] A sealed first cavity 130 and a second cavity 140 are formed between the MEMS wafer 110 and the cover wafer 120. The first cavity 130 and the second cavity 140 are independent of each other.

[0019] The first cavity 130 is configured for a first function. For example, the first function is a MEMS accelerometer, and a MEMS accelerometer component 131 is disposed in the first cavity 130. The second cavity 140 is configured for a second function. For example, the second function is a MEMS gyroscope, and a MEMS gyroscope component 141 is disposed in the second cavity 140.

[0020] As Figure 2-3 shown, the MEMS wafer 110 includes: a substrate 111, an anchor oxide layer 112 formed on the substrate 111, a MEMS device layer 113 formed on the anchor oxide layer 112, and a first metal layer 114 formed on the MEMS device layer. The MEMS accelerometer component 131 and the MEMS gyroscope component 141 are located in the MEMS device layer 113.

[0021] As Figure 1 , 3 shown, the cover wafer 120 includes a second metal layer 121, a first groove 122, and a second groove 123 formed on one side thereof. The first metal layer 114 of the MEMS wafer 110 is bonded to the second metal layer 121 of the cover wafer 120. The first groove 122 and the corresponding part on the MEMS wafer form the first chamber 130, and the second groove 123 and the corresponding part on the MEMS wafer 110 form the second chamber 140. In a specific implementation, the MEMS wafer 110 and the first cover wafer 120 are eutectic bonded together.

[0022] Specifically, the first metal layer 114 includes an aluminum layer, the second metal layer 121 includes a germanium layer, and an integrated circuit structure formed based on a CMOS process is formed in the base layer 111.

[0023] The MEMS device further includes a gas release material layer 151 formed on the MEMS wafer 110 and / or the cover wafer 120. The gas release material layer 151 is exposed to the first cavity 130. The gas release material layer 151 releases gas into the first cavity 130 during the bonding process of the MEMS wafer 110 and the cover wafer 120 or when heated, so as to change the pressure in the first cavity 130.

[0024] The pressure in the first cavity 130 depends on the pressure of the bonding environment when the MEMS wafer 110 and the cover wafer 120 are bonded and the amount of gas released by the gas release material layer 151 into the first cavity. The pressure in the second cavity 140 depends on the pressure of the bonding environment when the MEMS wafer 110 and the cover wafer 120 are bonded. Specifically, the pressure of the bonding environment when the MEMS wafer 110 and the cover wafer 120 are bonded is the pressure in the bonding tool. For example, the pressure of the bonding environment when the MEMS wafer 110 and the cover wafer 120 are bonded can be vacuum or approximately vacuum.

[0025] During the bonding process, the gas release material layer 151 is baked to release gas into the first cavity 130. Optionally, the MEMS device can also be heated separately to heat the gas release material layer 151 to release gas.

[0026] In Figure 3 , a gas release material layer 151 is provided on the MEMS wafer, and a gas release material layer 151 is also provided on the cover wafer. In some embodiments, the gas release material layer 151 can be provided only on the MEMS wafer or the cover wafer. The position of the gas release material layer 151 can be selected according to needs.

[0027] Specifically, the gas release material layer 151 is deposited and patterned on the MEMS wafer 110 or the cover wafer 120. The MEMS device further includes: a sealing layer 152 deposited on and patterned over the gas release material layer 151. The patterned sealing layer 152 seals the gas release material layer 151 corresponding to the second cavity 140 so that the gas release material layer is not exposed to the second cavity 140, and the patterned sealing layer cannot seal the gas release material layer corresponding to the first cavity 130 so that the gas release material layer is exposed to the first cavity 130. In this way, during the bonding process of the MEMS wafer and the cover wafer or when the gas release material layer is heated, only the gas release material layer exposed to the first cavity 130 releases gas into the first cavity 130, and the gas release material layer not exposed to the second cavity 140 does not release gas into the second cavity 140. Since the gas release material layer in the second cavity 140 is sealed, the second cavity 140 maintains its original pressure.

[0028] Preferably, by adjusting the structure of the sealing layer 152 deposited on and patterned over the gas release material layer 151, the area or volume of the gas release material layer 151 exposed to the first cavity 130 can be adjusted, so that the amount of gas released from the gas release material layer 151 into the first cavity can be adjusted.

[0029] According to another aspect of the present invention, the present invention provides a manufacturing method of a MEMS device with two independent cavities. Figure 4 It is a schematic flowchart of the manufacturing method of the MEMS device in the present invention. As Figure 4 shown, the manufacturing method includes the following steps.

[0030] Step 410, providing a MEMS wafer 110 and a first cover wafer 120, on which a gas release material layer 151 is formed.

[0031] Step 420, bonding the MEMS wafer 110 and the cover wafer 120, wherein a sealed first cavity 130 and a second cavity 140 are formed between the MEMS wafer 110 and the cover wafer 120, the gas release material layer 151 is exposed to the first cavity 130, and the gas release material layer 151 releases gas into the first cavity 130 during the bonding process of the MEMS wafer 110 and the cover wafer 120 or when heated to change the pressure in the first cavity.

[0032] The pressure in the first cavity 130 depends on the pressure of the bonding environment when the MEMS wafer 110 is bonded to the cover wafer 120 and the amount of gas released by the gas release material layer 151 into the first cavity. The pressure in the second cavity 140 depends on the pressure of the bonding environment when the MEMS wafer 110 is bonded to the cover wafer 120. Specifically, the pressure of the bonding environment when the MEMS wafer 110 is bonded to the cover wafer 120 is the pressure in the bonding tool. For example, the pressure of the bonding environment when the MEMS wafer 110 is bonded to the cover wafer 120 can be a vacuum or approximately a vacuum.

[0033] During the bonding process, the gas release material layer 151 is baked to release gas into the first cavity 130. Optionally, the MEMS device can also be heated separately to heat the gas release material layer 151 to release gas.

[0034] In Figure 3 of them, a gas release material layer 151 is provided on the MEMS wafer, and a gas release material layer 151 is also provided on the cover wafer. In some embodiments, the gas release material layer 151 can be provided only on the MEMS wafer or the cover wafer. The position of the gas release material layer 151 can be selected according to needs.

[0035] Specifically, the providing of the MEMS wafer and the cover wafer 401 includes:

[0036] Depositing and patterning the gas release material layer 151 on the MEMS wafer 110 or the cover wafer 120;

[0037] Depositing and patterning a sealing layer 152 on the gas release material layer 151,

[0038] The patterned sealing layer 152 seals the gas release material layer corresponding to the second cavity 140 so that the gas release material layer is not exposed to the second cavity 140, and the patterned sealing layer 152 does not seal the gas release material layer corresponding to the first cavity 130 so that the gas release material layer 151 is exposed to the first cavity. In this way, during the bonding process of the MEMS wafer and the cover wafer or when the gas release material layer is heated, only the gas release material layer exposed to the first cavity 130 will release gas into the first cavity 130, and the gas release material layer not exposed to the second cavity 140 will not release gas into the second cavity 140. Since the gas release material layer in the second cavity 140 is sealed, the second cavity 140 maintains its original pressure.

[0039] During the bonding process or when heated, the gas release material layer exposed to the first cavity releases gas into the first cavity to change the pressure in the first cavity, while the second cavity maintains its original pressure, thereby obtaining a first cavity 130 and a second cavity 140 with different pressures.

[0040] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0041] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications and variations to the above embodiments within the scope of the present invention.

Claims

1. A MEMS device, characterized in that, It includes: A MEMS wafer; A cover wafer bonded to the MEMS wafer, wherein a sealed first cavity and a second cavity are formed between the MEMS wafer and the cover wafer; A gas release material layer formed on the MEMS wafer or / and the cover wafer, the gas release material layer is exposed to the first cavity, and the gas release material layer releases gas into the first cavity during the bonding process of the MEMS wafer and the cover wafer or when heated to change the pressure in the first cavity.

2. The MEMS device according to claim 1, wherein The first cavity is configured for a first function, and the second cavity is configured for a second function, The first function is a MEMS accelerometer, and the second function is a MEMS gyroscope, A MEMS accelerometer component is provided in the first cavity, and a MEMS gyroscope component is provided in the second cavity.

3. The MEMS device according to claim 2, wherein The MEMS wafer includes: A substrate; An oxide anchor layer formed on the substrate; A MEMS device layer formed on the oxide anchor layer, wherein the MEMS gyroscope component and the MEMS accelerometer component are located in the MEMS device layer; A first metal layer formed on the MEMS device layer, The cover wafer includes a second metal layer, a first groove and a second groove formed on one side thereof, The first metal layer of the MEMS wafer is bonded to the second metal layer of the cover wafer, and the first groove and the corresponding part on the MEMS wafer form the first chamber, and the second groove and the corresponding part on the MEMS wafer form the second chamber.

4. The MEMS device according to claim 3, wherein The first metal layer includes an aluminum layer, and the second metal layer includes a germanium layer, An integrated circuit structure is formed in the base layer.

5. The MEMS device according to claim 1, wherein The pressure in the first cavity depends on the pressure of the bonding environment when the MEMS wafer and the cover wafer are bonded and the amount of gas released by the gas release material layer into the first cavity, The pressure in the second cavity depends on the pressure of the bonding environment when the MEMS wafer and the cover wafer are bonded.

6. The MEMS device according to claim 5, wherein The gas release material layer is deposited and patterned on the MEMS wafer or the cover wafer, The MEMS device further includes: a patterned sealing layer deposited on the gas release material layer, The patterned sealing layer seals the gas release material layer corresponding to the second cavity so that the gas release material layer is not exposed to the second cavity, and the patterned sealing layer does not seal the gas release material layer corresponding to the first cavity so that the gas release material layer is exposed to the first cavity.

7. The MEMS device according to claim 6, wherein By adjusting the area or volume of the gas release material layer exposed to the first cavity, the amount of gas released by the gas release material layer into the first cavity is adjusted.

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