WO2019022351A1

WO2019022351A1 - Mems sensor and manufacturing method thereof

Info

Publication number: WO2019022351A1
Application number: PCT/KR2018/005267
Authority: WO
Inventors: 이상우; 송기무; 안재현; 김용국
Original assignee: 주식회사 신성씨앤티
Priority date: 2017-07-26
Filing date: 2018-05-08
Publication date: 2019-01-31
Also published as: KR101988469B1; KR20190012297A

Abstract

Provided are a MEMS sensor and a manufacturing method thereof. The MEMS sensor includes: a device substrate on which a device pattern is formed; a cap wafer disposed above the device substrate and including a cavity area; a via wafer disposed below the device substrate; and a cap trench which, on the contact surface of the device substrate and the cap wafer, passes through the device substrate, and has a portion accommodated in the cap wafer to connect the device substrate and the cap wafer, wherein the cap trench is earthed and the device substrate is joined with the cap wafer and the via wafer by means of high temperature fusion bonding to be able to suppress the generation of static electricity and reduce parasitic noise.

Description

MEMS sensor and manufacturing method thereof

The present invention relates to a MEMS sensor and a manufacturing method thereof.

Micro Electro Mechanical Systems (MEMS) is a technology that implements mechanical and electrical components using a semiconductor process. Typical examples of devices using MEMS technology include MEMS angular velocity sensor for measuring angular velocity and MEMS Acceleration sensors. In recent years, as the market for portable electronic devices such as smart phones and smart pads grows, demand for combo-type MEMS products that make multiple MEMS devices into a single chip is gradually increasing.

Since the production process of the MEMS device basically follows the semiconductor process, the process of etching and etching a thin film by using a wafer made of a material such as silicon as a substrate, contacting another wafer, .

For wafer-to-wafer bonding, fusion bonding can be used. In the case of silicon wafers, the bonding surface is changed to silicon oxide by fusion bonding and bonding occurs.

Fusion bonding involves low temperature fusion bonding using relatively low temperatures and high temperature fusion bonding using relatively high temperatures. Among them, the high-temperature fusion bonding does not require a pretreatment process as compared with the low-temperature fusion bonding, and when the proper pressure condition is satisfied, good results can be obtained and the process cost is lower.

Although the MEMS sensor is manufactured in various ways, the MEMS sensor of the present patent includes a via wafer serving as a base, a device substrate forming a sensor structure, and a cover cap wafer .

During the fabrication of the MEMS sensor, the sensor structure sticks to the cap wafer or the via wafer, that is, stiction occurs. There are various causes of stiction. Typically, it is caused by capillary force and charging effect caused by drying process of wet chemical or DI water, and electrostatic force is the most common cause. If stiction occurs, normal operation of the sensor becomes impossible.

A problem to be solved by the present invention is to provide a method for preventing stiction in a method of manufacturing a MEMS sensor, and another object is to provide a MEMS combo sensor without stiction.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a MEMS sensor including: a device substrate on which a device pattern is formed; A cap wafer disposed on the device substrate and including a cavity region; A via wafer disposed under the device substrate; And a cap trench passing through the device substrate at a contact surface between the device substrate and the cap wafer and partially accommodated in the cap wafer to electrically connect the device substrate and the cap wafer, And a high temperature fusion bonding method with the via wafer.

The cap trench may be filled with poly-silicon.

The cap trench may be in contact with the via wafer.

The cap trench may be grounded.

The MEMS sensor according to the embodiment may further include a bumper formed in the cavity region of the cap wafer.

The bumper may be etched to a depth less than the depth of the cavity region.

The structure formed on the device substrate may include a bumper.

The bumper formed on the structure may be formed on one structural surface or on both structural surfaces between two opposed structures.

The via-wafer may be a doped silicon substrate, and the via-wafer may be formed with a trench via which the via-wafer is vertically penetrated and filled with an insulator.

On the upper surface of the via wafer, the cavity may be further etched.

A recess may be formed on the upper surface of the via wafer.

The depth of the recess may be less than the depth of the cavity.

When the MEMS sensor is an acceleration sensor, a vent hole opened to the outside may be formed in the via wafer.

A conductive layer and a passivation layer may be formed on the lower surface of the via wafer.

According to another aspect of the present invention, there is provided a method of manufacturing a MEMS sensor including a via wafer, a device substrate, and a cap wafer, the cap wafer and the device substrate being bonded by high temperature fusion bonding ), A device substrate and an upper cap wafer are electrically connected by forming a trench through the device substrate and accommodating a part of the cap wafer and filling the trench with a conductor, and the via wafer and the device substrate Lt; RTI ID = 0.0 > high temperature fusion bonding < / RTI >

A method of manufacturing a MEMS sensor according to an embodiment includes a bumper formed on the structure.

The method of fabricating a MEMS sensor may further include forming a trench via filled with an insulator in the doped via wafer and etching the cavity on an upper surface of the via wafer.

The method of manufacturing a MEMS sensor according to an embodiment may further include forming a recess on the upper surface of the via wafer by etching.

The method of manufacturing a MEMS sensor according to an embodiment may further include forming a bumper in a cavity formed in the cap wafer.

The method of manufacturing a MEMS sensor according to an embodiment may further include forming a vent hole opened to the outside on the via wafer.

The method of manufacturing a MEMS sensor according to an embodiment may further include forming a conductive layer and a passivation layer on a lower surface of the via wafer.

Other specific details of the invention are included in the detailed description and drawings.

According to the MEMS sensor manufacturing method according to some embodiments of the present invention, stiction of the MEMS structure can be prevented. Also, the electromagnetic wave interference can be greatly reduced by grounding the cap wafer. In addition, according to the method of manufacturing a MEMS sensor according to some embodiments of the present invention, a MEMS sensor capable of greatly reducing signal parasitic noise can be manufactured through a simple additional process. This reduction in parasitic noise greatly improves the signal-to-noise ratio (SNR).

If the method of manufacturing a MEMS sensor according to the embodiments of the present invention is used, stiction phenomenon does not occur and a MEMS sensor can be produced at a low cost.

1 is a side cross-sectional view of a MEMS sensor according to an embodiment of the present invention.

2 is a side cross-sectional view of a pre-via wafer of a MEMS sensor according to an embodiment of the present invention.

3 is a side cross-sectional view illustrating a situation where a cavity and a recess are formed in a pre-via wafer according to an embodiment of the present invention.

4 is a side cross-sectional view of a cap wafer according to an embodiment of the present invention.

5 is a side cross-sectional view illustrating a situation in which a cap wafer according to an embodiment of the present invention is bonded to a SOI wafer.

6 is a side cross-sectional view illustrating a state in which a handle substrate is removed from a SOI wafer bonded to a cap wafer according to an embodiment of the present invention, and only a device substrate remains.

7 is a side cross-sectional view illustrating a state in which a cap trench is formed on a device substrate bonded to a cap wafer according to an embodiment of the present invention.

8 is a side cross-sectional view illustrating a device patterning process performed on a device substrate bonded to a cap wafer according to an embodiment of the present invention.

9 is a side cross-sectional view illustrating a state in which a pre-via wafer is bonded to a device substrate on which a cap trench is formed according to an embodiment of the present invention.

10 is a side cross-sectional view illustrating a state in which a pre-via wafer removal region of a MEMS sensor is removed according to an embodiment of the present invention.

11 is a view illustrating a state in which a vent hole is formed in a via wafer of a MEMS sensor according to an embodiment of the present invention.

12 is a side cross-sectional view illustrating a state in which a passivation layer and a conductive layer are stacked on a via wafer bottom surface of a MEMS sensor according to an embodiment of the present invention.

FIG. 13 is a circuit diagram showing an equivalent circuit equivalent to a situation before removing a removal region in a pre-via wafer of a MEMS sensor according to an embodiment of the present invention. FIG.

14 is a circuit diagram showing an equivalent circuit equivalent to a situation after removing a removal region in a pre-via wafer of a MEMS sensor according to an embodiment of the present invention.

15 is a circuit diagram showing an equivalent circuit equivalent to a situation in which a cap trench is formed in a MEMS sensor according to an embodiment of the present invention.

* Explanation of symbols

1: MEMS sensor 10: Device substrate

11: cap trench 12: device pattern

13: handle substrate 20: cap wafer

21: cavity area 22: bumper

24: passivation film 30: via wafer

31: trench vias 32: cavity

33: recess 35: vent hole

40: passivation layer 41: conductive layer

100: Bundle substrate 121: Acceleration sensor pattern

122: gyro sensor pattern 211: first cavity area

212: second cavity region 231: first sealing wall

232: second sealing wall 233: third sealing wall

300: Previa wafer 341: Use area

342: Removal area

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

It is to be understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected or coupled to another element, One case. On the other hand, when an element is referred to as being " directly coupled to " or " directly coupled to " another element, it means that it does not intervene in another element. &Quot; and / or " include each and every combination of one or more of the mentioned items.

It is to be understood that an element is referred to as being " on " or " on " of another element includes both elements immediately above and beyond other elements. On the other hand, when an element is referred to as being " directly on " or " directly above " another element, it means that it does not intervene another element in the middle.

The terms spatially relative, "below", "beneath", "lower", "above", "upper" Can be used to easily describe the correlation of components with other components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element . Thus, the exemplary term " below " can include both downward and upward directions. The components can also be oriented in different directions, so that spatially relative terms can be interpreted according to orientation.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions.

Although the first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical scope of the present invention.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, a MEMS sensor 1 according to an embodiment of the present invention will be described with reference to the drawings.

1 is a side cross-sectional view of a MEMS sensor 1 according to an embodiment of the present invention.

Referring to FIG. 1, a MEMS sensor 1 according to an embodiment of the present invention includes cap wafer 20, device substrate 10, and via wafer 30, And a passivation layer is formed on the lower surface of the substrate. Each substrate can be composed of a silicon wafer.

The via wafer 30 is a constituent element serving as a base of the MEMS sensor 1 according to an embodiment of the present invention.

The via wafer 30 is provided with an anchor to which the MEMS sensor formed on the device substrate 10 is fixed or a sensing electrode that senses the movement of the MEMS sensor (12 in FIG. 8) A driving electrode and the like may be formed. The electrodes may be silicon through electrodes.

The device substrate 10 is a substrate on which a MEMS sensor 1 according to an embodiment of the present invention is formed. Therefore, it may include a sensor mass, and the pattern may be formed differently depending on the type of the sensor to be formed. For example, the device pattern 12 may be a MEMS-based angular velocity sensor or an acceleration sensor. A bumper for preventing stiction may be formed in the device pattern. The device substrate 10 may be a low resistance silicon wafer of about 0.01? Cm, but the present invention is not limited thereto.

An accelerometer pattern 121 and a gyroscope pattern 122 may be formed on the device substrate 10 of the MEMS sensor 1 according to an embodiment of the present invention. The acceleration sensor 121 operates optimally at atmospheric pressure and the gyro sensor 122 operates optimally at a vacuum.

The cap wafer 20 is a component for covering the MEMS sensor 1 according to an embodiment of the present invention and serves to protect the MEMS sensor 1 of the present invention from external factors.

The cap wafer 20 may be disposed on the device substrate 10 and the cap wafer 20 may have a first cavity region 211 formed therein. The cap wafer 20 may be mechanically connected by a high temperature fusion bonding method between the device substrate 10 and the wafer. The first cavity region 211 is a sealed space formed by joining the cap wafer 20 and the device substrate 10 together.

The cavity region 21 may be formed to have a step with respect to the surface of the cap wafer 20. That is, a part of the surface of the cap wafer 20 can be etched to form a void space, and this void space can be the cavity region 21. [ The cavity region 21 is formed to correspond to an area where the device pattern 12 is formed in the device substrate 10 and provides a space in which the device pattern 12 can move when the device pattern 12 moves up and down It plays a role. For example, the device pattern 12 may be an acceleration sensor or a gyro sensor, and the device pattern 12 may be vibrated up, down, left, and right depending on the movement of the user.

The cavity region 21 may be formed to include at least one. This is because the device pattern 12 formed on the device substrate 10 may have a complex shape and a plurality of regions where the device pattern 12 vibrates may exist. At least one cavity region 21 may be formed so as to correspond thereto.

In the passivation layer, a conductive layer for electrically connecting the MEMS sensor 1 to an external circuit board and a passivation layer 40 for protecting the conductive layer except the pad region from external factors are formed in the passivation layer .

Hereinafter, a method of manufacturing the MEMS sensor 1 according to an embodiment of the present invention will be described with reference to FIGS.

2 is a side cross-sectional view of a pre-via wafer 300 of a MEMS sensor 1 according to an embodiment of the present invention.

The pre-via wafer 300 may be a conductive doped silicon substrate, but is not limited thereto. The previa wafer may be another semiconductor substrate such as germanium, and the dopant may be phosphorus or boron, but is not limited thereto.

The pre-via wafer 300 can be processed into the via wafer 30 at a later stage. The previa wafer 300 may include a use region 341 and a removal region 342 depending on the thickness to be processed into the via wafer 30. [ The use area 341 is a later processed and used area, and the removed area 342 can be a later removed area. The thickness of the removal region 342 may be greater than the thickness of the use region 341, but is not limited thereto. In addition, the pre-via wafer 300 can be marked using means such as UV-laser.

The trench vias 31 are formed in the pre-via wafer 300 of the MEMS sensor 1 according to an embodiment of the present invention. The trench vias 31 may be formed in an annular shape by being formed downwardly from the upper surface of the pre-formed wafer 300. However, the shape of the trench vias 31 is not limited thereto.

The trench vias 31 may be formed deeper than the use region 341. [ In other words, the trench vias 31 can be formed up to a part of the upper portion of the removal region 342.

After the trench vias 31 are etched and formed, the trench vias 31 may be filled with an insulator. As the insulator filling the trench vias 31, a silicon nitride film and a silicon oxide film can be used, but the present invention is not limited thereto.

3 is a side cross-sectional view illustrating a situation in which a cavity 32 and a recess 33 are formed in a pre-formed wafer 300 according to an embodiment of the present invention.

Referring to FIG. 3, a cavity 32 is formed in the upper surface of the pre-formed wafer 300 on which the trench vias 31 are formed, in which a portion of the region between the trench vias 31 is etched. The cavity 32 is a component formed to prevent stiction against the via wafer 30 of the device substrate 10, which will be described later in detail. Therefore, it is preferable that the cavity 32 is formed below the device pattern moving in the vertical direction. Here, the depth at which the cavity 32 is etched is smaller than the depth of the trench vias 31.

A recess 33 may be formed on the upper surface of the pre-formed wafer 300 in which the cavity 32 is formed. The recess 33 is a component for securing the minimum clearance desired to be held by the via wafer 30 and the device substrate 10 and is formed by etching the remaining region of the upper surface of the pre- . Accordingly, a portion of the upper portion of the trench via 31 filled with the insulator can be etched to form the recess 33. The depth of the recess (33) is formed to be smaller than the depth of the cavity (32).

4 is a side cross-sectional view of a cap wafer 20 according to an embodiment of the present invention.

On the other hand, the cap wafer 20 can form a cavity region 21 by etching a part of the lower surface thereof. In the MEMS sensor 1 according to the embodiment of the present invention, two cavity regions 21 are formed to form the first cavity region 211 and the second cavity region 212, Corresponds to the area of the sensor.

The first cavity region 211 and the second cavity region 212 are separated by a first sealing wall 231 and are separated from the outside by a second sealing wall 232 and a third sealing wall 233 . At this time, the bumper 22 can be formed in the cavity region 21. [ Since the bumper 22 is a component formed to prevent stiction of the device substrate 10 against the cap wafer 20 or the via wafer 30 as will be described later in detail, the device substrate 10, which moves in the vertical direction, It is preferable that the sensor masses of the sensor masses are formed at positions close to each other. Here, the depth at which the bumper 22 is etched is lower than the depth of the cavity region 21.

Although the bumper 22 is illustrated as being formed only in the first sealing wall 231 and the second sealing wall 232 surrounding the first cavity area 211 in the embodiment of the present invention, But is not limited thereto.

A passivation film 24 may be formed on the top and bottom of the cap wafer 20.

5 is a cross-sectional side view showing a state in which the cap wafer 20 according to an embodiment of the present invention is bonded to a soy wafer.

5, the SOI wafer 100 including the device substrate 10 and the handle substrate 13 is positioned at the lower end of the cap wafer 20 to confirm that the SOI wafer 100 is bonded.

The junction of the high temperature fusion bonding system is performed while the SOI wafer is in contact with the lower end of the cap wafer 20, that is, the distal end portions of the sealing

walls

231, 232, and 233. It is preferable to conduct the high temperature fusion bonding at a temperature of 1050 ° C. As a result, bonding occurs between the bonding surfaces of the cap wafer 20 and the SOI wafer 100, and a single substrate is formed.

6 is a side cross-sectional view showing a state in which the handle substrate 13 is removed from the SOI wafer 100 bonded to the cap wafer 20 according to the embodiment of the present invention.

The handle substrate 13 located at the lower end of the SOI wafer 100 is not used and must be removed. Therefore, it is removed using a process such as CMP (chemical mechanical polishing). Therefore, since the handle substrate 13 is removed from the SOI wafer 100, only the device substrate 10 remains bonded to the cap wafer 20.

7 is a side cross-sectional view illustrating a state in which a cap trench 11 is formed in a device substrate 10 bonded to a cap wafer 20 according to an embodiment of the present invention.

The cap trench 11 is formed to penetrate the device substrate 10 and to be partially accommodated in the cap wafer 20 in a situation where the device substrate 10 and the cap wafer 20 are bonded via high temperature fusion bonding. That is, the cap trench 11 is formed to penetrate the upper and lower surfaces of the device substrate 10 in the device substrate 10, and is etched by a certain depth at the contact surface where the cap substrate 20 meets the device substrate 10.

The cap trench 11 may be filled with a conductive conductor. The conductor filled in the cap trench 11 may be polycrystalline silicon (polysilicon) and may be doped polycrystalline silicon.

The cap trench 11 filled with the conductive material is electrically connected to the cap wafer 20 and one end located on the device substrate 10 side is grounded to ground the cap wafer 20 to reduce electromagnetic noise, The stiction due to the electrostatic force can be prevented.

Although the cap trench 11 is illustrated as being formed only in the third sealing wall 233 adjacent to the second cavity region 212 in the embodiment of the present invention, the position where the cap trench 11 is disposed is not limited thereto .

8 is a side cross-sectional view showing a state in which device patterning is performed on a device substrate 10 bonded to a cap wafer 20 according to an embodiment of the present invention.

Referring to FIG. 8, device patterning is performed on the device substrate 10 to form a pattern of a desired sensor, thereby confirming that the device substrate 10 is completed. The acceleration sensor pattern 121 is formed on the device substrate 10 under the first cavity region 211 and the gyro sensor pattern 122 is formed on the device substrate 10 under the second cavity region 212. In this case, However, the pattern of the device substrate 10 of the present invention is not limited thereto, and can be changed according to the application.

A lithography process, a dry etching process, a strip process, a clean process, or the like may be used to perform device patterning on the device substrate 10, but the process is not limited thereto.

9 is a side cross-sectional view illustrating a situation where a previa wafer 300 is bonded to a device substrate 10 on which a cap trench 11 is formed according to an embodiment of the present invention.

Bonding of the high-temperature fusion bonding system is performed while the pre-via wafer 300 is in contact with the lower end of the device substrate 10. It is preferred that the high temperature fusion bonding be performed at a temperature of 1050 ° C and a pressure of 10 mTorr.

Since the recess 33 is formed on the upper surface of the pre-formed wafer 300, the outer periphery of the pre-formed wafer 300 serves as a kind of wall, and a portion bonded to the device substrate 10 do.

Bonding occurs at the contact of the device substrate 10 and the pre-via wafer 300, and an integral sensor is formed.

The device substrate 10 and the cap trench 11 formed on the cap wafer 20 are formed to penetrate the device substrate 10 and therefore contact the via wafer 30. [

10 is a side cross-sectional view showing a state in which the removal region 342 of the pre-via wafer 300 of the MEMS sensor 1 is removed according to an embodiment of the present invention.

Since only the use region 341 of the pre-formed wafer 300 is used for the MEMS sensor 1, the removed region 342 located under the use region 341 can be removed. Removal of the removal region 342 may utilize CMP, but is not limited thereto. The pre-via wafer 300 can be a via wafer 30 with the removal region 342 removed.

As the removal region 342 is removed, the trench vias 31 can penetrate the via wafer 30. That is, the lower surface of the trench vias 31 can be exposed to the outside.

11 illustrates a state in which a vent hole 35 is formed in a via wafer 30 of a MEMS sensor 1 according to an embodiment of the present invention.

As described above, the gyro sensor works well in a vacuum, and the acceleration sensor works well in an atmosphere similar to atmospheric pressure. Therefore, since vacuum must be maintained in a region formed by the via wafer 30 under the second cavity region 212 in which the gyro sensor is formed, it is sufficient that the substrates bonded through the fusion bonding are maintained in a sealed state.

However, since an atmosphere similar to atmospheric pressure should be formed in a region formed by the via wafer 30 under the first cavity region 211 in which the acceleration sensor is formed, a vent hole 35 capable of entering and exiting the outside and the gas can be formed .

The vent hole 35 may be formed to penetrate the upper and lower portions of the via wafer 30. Therefore, since the acceleration sensor area is freely vented through the vent hole 35, the atmospheric pressure of the acceleration sensor area can be maintained equal to the atmospheric pressure of the outside.

12 is a cross-sectional side view showing a state in which the passivation layer 40 and the conductive layer 41 are laminated on the bottom surface of the via wafer 30 of the MEMS sensor 1 according to the embodiment of the present invention.

A passivation layer 40 may be formed on the undersurface of the via wafer 30. The material and method of forming the passivation layer 40 are as described above in the description of FIG.

A conductive layer 41 may be formed with the passivation layer 40. The conductive layer 41 is a component that becomes an electrical passage to electrically connect the sensor and the electrodes formed on the device substrate to the external circuit substrate. Therefore, one end is in contact with the via wafer 30 and the other end is opened. The conductive layer 41 may be formed by forming a seed layer and performing electroplating on the seed layer, but the method is not limited thereto. The conductive layer 41 may be formed of copper having high conductivity, but is not limited thereto.

The passivation layer 40 and the conductive layer 41 may be formed of a plurality of layers, and the materials constituting each layer may be formed differently.

The passivation layer 40 and the conductive layer 41 are laminated on the lower end of the via wafer 30 to complete the MEMS sensor 1 of the present invention.

With reference to the completed MEMS sensor 1 of Fig. 12, it is examined how stiction can be prevented by the structure of the cap wafer 20 and the via wafer 30 of the present invention.

A bumper 22 is formed in the cavity region 21 of the cap wafer 20. The bumper serves to prevent stiction. The bumper formed on the cap wafer prevents stiction in the vertical direction and the bumper formed on the device pattern prevents stiction in the lateral direction. The principle of preventing bumper stiction is as follows. In order for the stiction to occur, a portion of the MEMS sensor may be subjected to initial contact with a fixed structure facing narrowly spaced (in the present invention, a recess formed in the via wafer or a sensing / driving electrode formed in the device substrate) This contact should develop into a permanent bond. In the absence of a bumper, when the MEMS sensor is exposed to stiction-inducing forces, such as capillary force or static power, the initial contact is easy to develop with permanent bonding, but if there is a bumper, Thereby making permanent adhesion difficult to occur.

The bumper 22 may be formed around the second cavity region 212 while the bumper 22 is formed only around the first cavity region 211 in the cap wafer 20. In this case, And can be formed in a part of the via wafer 30 where bonding can easily occur due to the up-and-down vibration of the device substrate 10.

As described above, in the present invention, the bumper 22 can be formed on the cap wafer 20, but even if another bumper is formed on the device substrate 10, the stiction can be prevented. At this time, the bumper formed on the device substrate protrudes toward the cavity 211 of the cap wafer. Of course, the bumper 22 of the cap wafer 20 and the bumper of the device substrate 10 may be formed together.

The bumper may be formed to prevent the stiction (stiction in the vertical direction) between the device substrate 10 and the cap wafer 20 as described above. However, in the

device substrate

10, 10, the bumper may be formed so as to prevent stiction (stiction in the horizontal direction) between the anchors. At this time, at least one bumper may be formed on the side surface of the oscillating portion, the bumper protruding in the direction of the anchor and the bumper protruding in the lateral direction of the oscillating portion from the side of the anchor.

A cavity 32 is formed between the trench vias 31 of the via wafer 30 as described above. The cavity 32 is formed by etching downward. Since both the capillary force and the electrostatic force become small as the gap between the structure and the substrate becomes large, stiction can be prevented by forming the cavity. Although the cavity 32 is formed only around the acceleration sensor pattern 121 in the embodiment of the present invention, the cavity 32 may be formed around the gyro sensor pattern 122.

Hereinafter, with reference to FIG. 13 to FIG. 15, a description will be made of a method by which the cap trench 11 can prevent stiction by the electrostatic force of the MEMS sensor 1.

13 is a circuit diagram showing an equivalent circuit equivalent to a situation before removing the removal region 342 in the pre-via wafer 300 of the MEMS sensor 1 according to the embodiment of the present invention. That is, the equivalent circuit is shown except for the MEMS sensor 1 and the cap trench 11 in the step of FIG. 9, and therefore, FIG. 9 is also referred to.

Various electrodes may be formed on the MEMS sensor 1 according to an exemplary embodiment of the present invention. Typically, a driving electrode C1 and a sensing electrode C2 are formed between the via wafer, the cap wafer, and the MEMS sensor 1 And may include an unintentional parasitic electrode C3. C1 and C2 are electrodes arranged horizontally or vertically with the MEMS sensor, and C3 is an electrode disposed below or above the MEMS sensor. One terminal of these electrodes is in an electrically connected state before the removal regions 342, S are removed. The opposite terminals of these electrodes are all connected by a MEMS sensor structure (R).

The substrate is represented by a conductive wire having conductivity, and the electrode is represented by a capacitor.

14 is a circuit diagram showing an equivalent circuit equivalent to the situation after removing the removal region 342 in the pre-via wafer 300 of the MEMS sensor 1 according to the embodiment of the present invention. That is, the equivalent circuit is shown except for the MEMS sensor 1 and the cap trench 11 in the step of FIG. 10, and therefore, FIG. 10 is also referred to.

After the removal region 342 (S) is removed, the via wafer 30 is divided into portions by the trench vias 31. Since the insulator is filled in the trench vias 31, the respective portions of the via wafer 30 and C3 are electrically disconnected. Further, a passivation film 24 is formed between the cap wafer 20 and the device substrate, and is not electrically connected to each other. Thus, the electrodes are electrically isolated from each other, and the charge can be independently charged. When a charge is charged between the electrodes, an electrostatic force is generated and a stiction phenomenon may occur.

15 is a circuit diagram showing an equivalent circuit equivalent to a situation in which the cap trench 11 is formed in the MEMS sensor 1 according to the embodiment of the present invention. That is, since the circuit equivalent to the MEMS sensor 1 in the step of FIG. 10 is shown, FIG. 10 is also referred to.

When there is a conductive cap trench 11 (T), both the electrically isolated cap wafer and the one end C3 present in the via wafer are electrically connected to the sensor sensor structure R. Therefore, since no charge is accumulated at both ends of C3, no electrostatic force is generated.

Stiction is prevented by the action of the cap trench 11 (T), and generation of electromagnetic noise is suppressed.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims

A device substrate on which a device pattern is formed;

A cap wafer disposed on the device substrate and including a cavity region;

A via wafer disposed under the device substrate;

A cap trench passing through the device substrate and partially formed on the cap wafer at a contact surface between the device substrate and the cap wafer to spatially connect the device substrate and the cap wafer; And

And a conductor filled in the cap trench and electrically connecting the cap wafer and the device substrate.
The method according to claim 1,

Wherein the conductor is poly-silicon.
The method according to claim 1,

Wherein the conductor is grounded in contact with the via wafer.
The method according to claim 1,

And a bumper formed by etching surrounding the cavity region of the cap wafer.
5. The method of claim 4,

Wherein the bumper is formed by etching to a depth smaller than a depth of the cavity region.
The method according to claim 1,

And a bumper protruding toward the cap wafer on the device substrate.
The method according to claim 1,

A bumper protruding in the direction of the anchor on the side surface of the oscillating part and a bumper protruding in the lateral direction of the oscillating part from the side of the anchor so that the oscillating part of the device substrate does not stiction against the anchor of the device substrate And at least one bumper.
The method according to claim 1,

Wherein the via wafer is a doped silicon substrate,

Wherein the via wafer is formed with trench vias through which the via wafer is vertically passed and filled with an insulator.
9. The method of claim 8,

And a cavity is further formed on the upper surface of the via wafer in the region between the trench vias.
A device substrate on which a device pattern is formed;

A cap wafer disposed on the device substrate and including a cavity region;

A via wafer disposed under the device substrate; And

And a bumper surrounding the cavity region of the cap wafer and formed to have a step upward from a lower surface of the cap wafer.
11. The method of claim 10,

Wherein the bumper is formed by etching to a depth smaller than a depth of the cavity region.
11. The method of claim 10,

And a bumper protruding toward the cap wafer on the device substrate.
11. The method of claim 10,

A bumper protruding in the direction of the anchor on the side surface of the oscillating part and a bumper protruding in the lateral direction of the oscillating part from the side of the anchor so that the oscillating part of the device substrate does not stiction against the anchor of the device substrate And at least one bumper.