KR101210138B1 - Wafer level pakage of mems senser and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a MEMS sensor wafer level package and a method of manufacturing the same, which maximizes the sealing effect of the MEMS sensor and forms an upper cavity electrode in the upper glass, thereby providing excellent electrical connection between the MEMS sensor and the wafer level. The technology to provide a package.
The method of manufacturing a MEMS sensor wafer level package according to the present invention includes forming a lower cavity electrode and an upper cavity electrode on the lower glass and the upper glass, respectively, forming a via hole in the upper glass, and forming a MEMS structure on the lower glass. And forming an outer frame at an edge of an upper portion of the lower glass, and bonding the upper glass to an upper portion of the outer frame.

Description

Wafer level package of MEMS sensor and its manufacturing method {WAFER LEVEL PAKAGE OF MEMS SENSER AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a wafer level package of a MEMS sensor and a manufacturing method thereof, and more particularly to a wafer level package of a MEMS sensor including an upper cavity electrode.

The general MEMS device package and its manufacturing method are as follows.

First, a MEMS device is mounted on a substrate, and a delayed photocurable epoxy is applied at the position where the sealing cap is attached. Then, predetermined light is applied to the delayed photocurable epoxy, and a sealing cap is attached onto the substrate. Subsequently, the process of completely curing the delayed photocurable epoxy at room temperature may be performed to manufacture a MEMS device package.

In addition to the above method, the MEMS device for performing a mechanical operation corresponding to the driving signal applied to the MEMS device and the base substrate and the MEMS device on which the MEMS device is mounted by flip chip bonding are formed on one surface of the MEMS device. There is a MEMS package element comprising a thin film to be shielded from and a photocurable sealing agent filling a space between the base substrate and the thin film.

However, the MEMS sensor package according to the related art cannot form an electrode on top of the cavity surrounding the 3D MEMS structure, and the process is expensive because the photocurable epoxy is used to maintain the sealing. In addition, since the photocurable epoxy is used, there is a problem that the sealing package may be broken due to heat deformation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer level package of a MEMS sensor and a method of manufacturing the MEMS sensor, which maximizes the sealing effect of the MEMS package and has excellent electrical connection between the inside and the outside of the MEMS sensor by forming an upper cavity electrode in the upper glass.

The method of manufacturing a MEMS sensor wafer level package according to the present invention includes forming a lower cavity electrode and an upper cavity electrode on the lower glass and the upper glass, respectively, forming a via hole in the upper glass, and forming a MEMS structure on the lower glass. And forming an outer frame at the edge of the upper portion of the lower glass, and bonding the upper glass to the upper portion of the outer frame.

Further, the method may further include forming a contact pad on the MEMS structure, wherein the via hole exposes the contact pad formed on the MEMS structure.

Meanwhile, the MEMS sensor wafer level package according to the present invention includes a lower glass including a lower cavity electrode, a MEMS structure provided on the lower glass, a contact pad provided on the MEMS structure, and an edge of an upper portion of the lower glass. And an upper frame bonded to the outer frame and the outer frame and including an upper cavity electrode and a via hole.

Further, the contact pads provided on the MEMS structure are exposed by the via holes.

As described above, the wafer level package of the MEMS sensor and the method of manufacturing the same according to the present invention provide the following effects.

First, the via glass provided in the upper glass may be electrically connected to the upper glass and the MEMS structure so that the metal electrode may not directly penetrate the inside and the outside of the cavity. Therefore, it is possible to maximize the effect of the sealing by blocking the source of the interference caused by the metal electrode directly connecting the inside and outside of the cavity.

Second, an upper cavity electrode may be formed on the upper part of the cavity surrounding the MEMS structure.

1A to 1E are cross-sectional views illustrating a method of manufacturing a MEMS sensor wafer level package according to the present invention.
2 is a perspective view illustrating a MEMS sensor wafer level package according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A to 1E are cross-sectional views illustrating a method of manufacturing a MEMS sensor wafer level package according to the present invention.

First, as shown in FIG. 1A, a method of forming the lower cavity electrode 105 on the lower glass 100 is as follows. After forming the photoresist pattern defining the cavity lower electrode region on the lower glass 100, the lower glass is partially etched using the photoresist pattern to form a trench. The photosensitive film pattern uses a negative photosensitive film having a thickness of 2 μm, and does not perform a hard baking process when forming the photosensitive film pattern. In addition, the trench is preferably formed at a depth of 200 nm by performing a wet etching process using a 6: 1 BOE solution for about 5 to 7 minutes.

Thereafter, a conductive layer is formed in the trench, and the lower cavity electrode 105 is formed by removing the photoresist pattern by wet. The lower cavity electrode 105 may be formed by using a low resistance wafer or by depositing a metal to reduce electrical resistance. For example, the conductive layer uses chromium (Cr) or gold (Au), and the thickness thereof is preferably 30 to 60 nm and 300 to 400 nm, respectively. After forming the lower cavity electrode 105, an annealing process is performed at a temperature of 400 degrees in N ₂ atmosphere.

Next, as shown in FIG. 1B, the upper cavity electrode 115 is formed on the upper glass 110. Here, the method of forming the upper cavity electrode 115 on the upper glass 110 is preferably formed by going through the same process as the method of forming the lower glass 100 described above. However, the upper cavity electrode 115 has a smaller line width than the lower cavity electrode 105. Next, referring to FIG. 1C, a plurality of via holes 120 are formed in the upper glass 110 with the upper and lower surfaces of the upper glass 110 turned upside down. Here, the reason for forming the via hole 120 in the upper glass 110 is to minimize parasitic resistance, and the via holes 120 may be connected in parallel outside the MEMS sensor.

Next, referring to FIG. 1D, a plurality of MEMS structures 130 are formed on the lower glass 100, and an outer frame 135 is formed on the edge of the lower glass 100. Some of the MEMS structures 130 are formed of silicon pillars, which are electrically connected to the lower cavity electrodes 105 to connect the lower cavity electrodes 105 to the outside. That is, the MEMS structure 130 is preferably formed to overlap the end of the lower cavity electrode 105. Thereafter, the contact pads 140 are formed on the MEMS structure 130. The MEMS structure 130 may be formed in various forms according to the type and role of the electrode. In this case, the contact pad 140 is formed on a part of the MEMS structure 130.

Next, referring to FIG. 1E, the upper glass 110 is bonded to the MEMS structure 130 and the outer frame 135. The upper glass 110 is disposed upside down such that the upper common electrode 115 faces the direction of the lower glass 100. Although the upper glass 110 is in contact with the outer frame 135, it is preferable not to be in contact with the MEMS structure 130.

Bonding the upper glass 110 is applied to the upper glass 110 with a voltage of 700 ~ 900V, and anodized them by an anodic bonding (anodic bonding) method to provide a temperature of 300 ~ 450 ℃ to the contact portion. . Anodic bonding is a method that is usefully used in sealing bonding between the outer frame 135 which is silicon and the upper glass 110 which is glass. In this anodic bonding, the eutectic junction is made by applying a temperature higher than the eutectic temperature of the metal constituting the silicon and the lower cavity electrode 105.

In addition, the contact pad 140 may be exposed by the via hole 120 of the upper glass 110. That is, the via hole 120 of the upper glass 110 is designed to be completely blocked by the silicon electrode pillar, which is the MEMS structure 130. As such, the upper glass 110 and the MEMS structure 130 may be electrically connected by the via hole 120 to prevent the metal electrode from directly passing through the inside and the outside of the cavity. Therefore, it is possible to maximize the effect of the sealing by blocking the damaging factors of the sealing caused in the process of connecting the metal electrode directly inside and outside the cavity.

Referring to the perspective view shown in Figure 2 the structure of the MEMS sensor formed by the method of 1a to 1e described above are as follows. At this time, it is not limited to the method similar to FIG. 1A-1E, It can form also in other methods.

Referring to FIG. 2, a plurality of MEMS structures 230 are provided on the lower glass 200 including the lower cavity electrode 205. At this time, some of the plurality of MEMS structures 230 is formed of a silicon pillar, which is electrically connected to the lower cavity electrode 205 and serves to connect the lower cavity electrode 205 to the outside. That is, the MEMS structure 130 is preferably formed to overlap the end of the lower cavity electrode 205.

In addition, the MEMS structure 230 may be designed such that structures for electrical connection with the mass-spring structure are arranged. The outer frame 235 is provided along the edge of the lower glass 200. The outer frame 235 structure can be designed to ensure sealing performance.

Finally, an upper glass 210 including an upper common electrode 215 is provided on the MEMS structure 230 and the outer frame 235. Although the upper glass 210 is in contact with the outer frame 235, it is preferable not to be in contact with the MEMS structure 230. In this case, a plurality of via holes 220 are included in the upper glass 210, and the via holes 220 may be configured to completely expose the contact pads 240 on the MEMS structure 230. That is, the via hole 120 of the upper glass 210 is designed to be completely blocked by the silicon electrode pillar, which is the MEMS structure 230. As such, the upper glass 210 and the MEMS structure 230 may be electrically connected by the via hole 220 to prevent the metal electrode from directly penetrating the inside and the outside of the cavity. Therefore, it is possible to maximize the effect of the sealing by blocking the damaging factors of the sealing caused in the process of connecting the metal electrode directly inside and outside the cavity.

The present invention is not limited only to the above embodiments, and various modifications can be made without departing from the spirit and scope of the present invention. It will be apparent to those skilled in the art that such modifications belong to the claims of the present invention. .

Claims (5)

Forming a lower cavity electrode and an upper cavity electrode on the lower glass and the upper glass, respectively;
Forming a via hole in the upper glass;
Forming a memes structure on the lower glass;
Forming an outer frame at an edge of an upper portion of the lower glass; And
Bonding the upper glass to the upper portion of the outer frame
MEMS sensor wafer level package manufacturing method comprising a. The method according to claim 1,
The method of claim 1, further comprising forming a contact pad on the MEMS structure. The method according to claim 2,
The via hole exposes the contact pads formed on the MEMS structure.
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