TWI546245B - Mems package structure - Google Patents

Description

MEMS package structure

This invention relates to a chip package structure, and more particularly to a MEMS package structure.

Microelectromechanical systems (MEMS) are microelectromechanical components fabricated in miniaturized package structures. The fabrication techniques are very similar to those used to fabricate integrated circuits, but microelectromechanical components interact with their surrounding environment. In traditional integrated circuits, such as mechanical, optical or magnetic interactions.

Microelectromechanical components can include very small electromechanical components (such as switches, mirrors, capacitors, accelerometers, sensors, capacitive sensors, or actuators), while MEMS components can be integrated into integrated circuits in a single block, while Improve insertion loss and electrical isolation of the entire solid state device. However, MEMS components are extremely fragile in the vast world of package structures and can be disrupted at any time by tiny static or surface tensions. Therefore, in order to avoid contamination or damage to the microelectromechanical element, it will typically be sealed in a space between the wafer and the cover.

1 is a schematic diagram of a conventional MEMS package structure. Referring to the drawings, a conventional MEMS package structure 10 includes a cover 12, a wafer 14, A colloid 16 and a microelectromechanical component 18 are provided. The cover 12 is secured to the wafer 14 by a sealant 16 to seal the microelectromechanical element 18 in the space between the wafer 14 and the cover 12.

However, although the space between the wafer 14 and the cover 12 is sealed by the encapsulant 16 in the conventional MEMS package structure 10, since there is a large gap between the cover 12 and the wafer 14, it is known After the MEMS package structure 10 is used for a period of time in a high humidity environment, the sealant 16 is more likely to be cracked, so that moisture easily penetrates into the space between the wafer 14 and the cover plate 12, thereby causing the MEMS element 18 to malfunction. .

The invention provides a microelectromechanical system package structure which has better moisture resistance.

A MEMS packaging structure of the present invention includes a wafer, a microelectromechanical component, a cover, a gel, and a first moisture barrier layer. The wafer has an active surface. The MEMS element is disposed on the active surface. The cover plate covers the wafer and includes a recess in which the microelectromechanical component is located. The encapsulant is disposed between the wafer and the cover to seal the recess, wherein the sealant has a thickness smaller than a height of the microelectromechanical component. The first moisture barrier layer is wrapped around the wafer, the encapsulant, and the cover.

In an embodiment of the invention, a first substrate, a second substrate, and a second moisture barrier layer are further included. The first substrate has a hole, wherein the wafer, the MEMS element, the cover plate, the encapsulant and the first moisture barrier layer are disposed in the hole. The second substrate is disposed on the first substrate to cover the hole. The second moisture barrier layer seals the first base An interface between the board and the second substrate.

In an embodiment of the invention, a molding compound is further included, disposed in the cavity and sealed around the first moisture barrier layer.

In an embodiment of the invention, a projection area of the molding compound on the first moisture barrier layer covers a projection area of the encapsulant on the first moisture barrier layer.

In an embodiment of the invention, a moisture absorbing member is further disposed in the hole.

In an embodiment of the invention, the second substrate has a region covering the encapsulant.

In an embodiment of the invention, the recess has an upper surface relative to the active surface, and the MEMS device includes a mirror, the distance between the active surface and the upper surface being greater than the tilt height of the mirror.

In an embodiment of the invention, the sealant has a thickness of between about 1 micrometer and 10 micrometers.

In an embodiment of the invention, the MEMS element comprises a mirror, a switch, a capacitor, an accelerometer, an inductor or an actuator.

In an embodiment of the invention, the material of the above-mentioned encapsulant comprises an epoxy resin.

Based on the above, the MEMS package structure of the present invention has a recess through the central portion of the cover plate, and the recess can be used for accommodating the MEMS component, reducing the gap height between the cover and the wafer, and transmitting through the sealant. Around the cover and the wafer The gap between them is to seal the pocket. Since the gap between the periphery of the cover plate and the wafer is small, the size of the sealant does not need to be too large, so that it is less likely to be cracked, so that the MEMS package structure of the present invention has better moisture resistance. In addition, the MEMS package structure of the present invention is coated around the wafer, the cover plate and the encapsulant through the first moisture barrier layer to prevent moisture from entering the recess and effectively providing the second weight protection. In addition, the MEMS package structure of the present invention further comprises disposing a wafer, a MEMS element, a cover plate, a sealant and a first moisture barrier layer in a hole surrounded by the first substrate and the second substrate, and borrowing A boundary region between the first substrate and the second substrate is sealed by the second moisture barrier layer to provide a third weight protection against moisture. Moreover, the MEMS package structure of the present invention provides a fourth weight protection against moisture by placing a molding compound in the cavity and adhering to the periphery of the first moisture barrier layer. Furthermore, the MEMS package structure of the present invention provides a fifth weight protection by arranging moisture absorbing elements in the holes to absorb moisture in the holes.

The above described features and advantages of the invention will be apparent from the following description.

D‧‧‧Distance

H‧‧‧ Height

10‧‧‧Learly MEMS packaging structure

12‧‧‧ Cover

14‧‧‧ wafer

16‧‧‧ Sealant

18‧‧‧Microelectromechanical components

100, 200, 300‧‧‧Microelectromechanical system package structure

110, 210‧‧‧ wafer

112‧‧‧Active surface

120, 220, 320‧‧‧ microelectromechanical components

130, 230‧‧ ‧ cover

132, 232, 332‧‧ ‧ pocket

132a‧‧‧ upper surface

140, 240, 340‧‧‧ Sealant

150, 250, 350‧‧‧ first moisture barrier

260, 360‧‧‧ first substrate

262, 362‧‧ holes

270, 370‧‧‧ second substrate

272‧‧‧Area

280‧‧‧Second moisture barrier

390‧‧‧Molding compounds

395‧‧‧Moisture absorption element

1 is a schematic diagram of a conventional MEMS package structure.

2 is a schematic diagram of a MEMS system package structure in accordance with an embodiment of the invention.

3 is a MEMS package structure in accordance with another embodiment of the present invention. Schematic diagram.

4 is a schematic diagram of a microelectromechanical system package structure in accordance with still another embodiment of the present invention.

Several preferred embodiments of the present invention will now be described in detail in conjunction with the drawings. 2 is a schematic diagram of a MEMS system package structure in accordance with an embodiment of the invention. Referring to FIG. 2 , the MEMS package structure 100 of the present embodiment includes a wafer 110 , a microelectromechanical component 120 , a cover 130 , a gel 140 , and a first moisture barrier layer 150 . Wafer 110 has an active surface 112. The wafer 110 is, for example, a light sensing wafer such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and the active surface 112 is, for example, a light sensing region, but the type of the wafer 110 and the active surface 112 is not limit.

The microelectromechanical component 120 is disposed on the active surface 112. In this embodiment, the microelectromechanical component 120 is a mirror, but in other embodiments, the microelectromechanical component 120 can also be a switch, a capacitor, an accelerometer, an inductor, or a deflector, and the type of the microelectromechanical component 120 is not limit.

In the present embodiment, the cover plate 130 is a transparent cover plate so that external light (not shown) can be transmitted through the cover plate 130 to the microelectromechanical element 120 and the active surface 112 of the wafer 110. As shown in FIG. 2, the cover plate 130 covers the wafer 110 and includes a recess 132 in which the microelectromechanical component 120 is located. The pocket 132 has an upper surface 132a relative to the active surface 112. In this embodiment, the active surface 112 and the upper surface A distance D between the surfaces 132a is greater than the height of the microelectromechanical element 120 (i.e., the tilt height of the mirror). In the present embodiment, the distance D between the active surface 112 and the upper surface 132a is about 10 microns, and the height H of a gap between the cover plate 130 and the wafer 110 is between about 1 micrometer and 10 micrometers. . That is, the height H of the gap between the cover plate 130 and the wafer 110 is smaller than the distance D between the active surface 112 and the upper surface 132a.

As shown in FIG. 2, the encapsulant 140 is disposed at a gap between the cover plate 130 and the wafer 110 to seal the recess 132a. The thickness of the encapsulant 140 is less than the height of the microelectromechanical element 120. As can be seen from the drawing, the thickness of the encapsulant 140 is limited by the height H of the gap between the periphery of the cap plate 130 and the wafer 110. Therefore, the thickness of the encapsulant 140 varies with the gap between the periphery of the cap plate 130 and the wafer 110. The height H varies. In this embodiment, the thickness of the encapsulant 140 ranges from about 1 micron to about 10 microns.

It is worth mentioning that in the present embodiment, the material of the encapsulant 140 is an organic compound such as an epoxy resin. Since the molecular structure of the organic compound has many hydrophilic groups, the sealant 140 can only block external pollution and part of moisture, but cannot completely block the hydrophilic groups and moisture in it. Therefore, in the present embodiment, the MEMS package structure 100 is coated around the wafer 110, the encapsulant 140, and the cap plate 130 by the first moisture barrier layer 150 to effectively block the hydrophilicity in the encapsulant 140. The action of the group with moisture enhances the impermeability of the pocket 132. As a result, the microelectromechanical component 120 can operate normally.

In this embodiment, the first moisture barrier layer 150 can be formed by chemical vapor deposition (CVD) or physical vapor deposition (physical vapor deposition). The vapor deposition (PVD) is formed, but the formation of the first moisture barrier layer 150 is not limited thereto. In addition, the first moisture barrier layer 150 is made of a highly dense inorganic insulating material such as cerium oxide, cerium nitride, cerium oxynitride or other nitrides, oxides and nitrogens containing no hydrophilic groups. The oxide has a moisture resistance that is greater than the moisture resistance of the sealant 140. That is to say, since the inorganic insulating material does not contain a hydrophilic group and thus does not act on moisture, it can effectively block moisture. Therefore, the first moisture barrier layer 150 can provide a second weight protection to reduce the possibility of moisture infiltration.

Compared with the conventional MEMS package structure 10, the MEMS package structure 100 of the present embodiment has a small gap between the cover plate 130 and the wafer 110, and is sealed between the cover plate 130 and the wafer 110. The sealant 140 does not need to be too large in size and is less prone to cracking. Moreover, the first moisture barrier layer 150 covers the periphery of the wafer 110, the encapsulant 140, and the cap plate 130 to provide better moisture resistance of the MEMS package structure 100.

3 is a schematic diagram of a microelectromechanical system package structure in accordance with another embodiment of the present invention. Referring to FIG. 3, the main difference between the MEMS package structure 200 of the present embodiment and the MEMS package structure 100 of the previous embodiment is that, in this embodiment, the MEMS package structure 200 further includes a first substrate. 260, a second substrate 270 and a second moisture barrier layer 280. The first substrate 260 has a hole 262. A wafer 210, a microelectromechanical component 220, a cover 230, a gel 240 and a first moisture barrier layer 250 are disposed in the holes 262. The second substrate 270 is disposed on the first substrate 260 to cover the hole 262. The second moisture barrier layer 280 is sealed first An interface between the substrate 260 and the second substrate 270.

Therefore, in the MEMS package structure 200, the first substrate 260, the second substrate 270, and the second moisture barrier layer 280 can provide a third weight protection to prevent moisture from entering the recess 232 and causing the microelectromechanical component. 220 failure.

In addition, in this embodiment, a majority of the area of the second substrate 270 is transparent so that an external light (not shown) can pass through the second substrate 270. The second substrate 270 has a region 272 overlying the encapsulant 240, that is, the projected region of the region 272 on the wafer 210 overlies the projected area of the encapsulant 240 on the wafer 210. In the present embodiment, the area 272 is a black area. Therefore, the region 272 can block external light from being irradiated to the encapsulant 240, and the chance of photodegradation of the encapsulant 240 is reduced.

4 is a schematic diagram of a microelectromechanical system package structure in accordance with still another embodiment of the present invention. Referring to FIG. 4, the main difference between the MEMS package structure 300 of the present embodiment and the MEMS package structure 200 of the previous embodiment is that, in this embodiment, the MEMS package structure 300 further includes a molding compound. 390 and a moisture absorbing element 395. The molding compound 390 is disposed within the hole 362 and attached to the periphery of the first moisture barrier layer 350. As shown in FIG. 4, a projection area of the molding compound 390 on the first moisture barrier layer 350 covers a projection area of the encapsulant 340 on the first moisture barrier layer 350. That is, the molding compound 390 can improve the physical structure of the sealant 340 and the first moisture barrier layer 350 to reduce the possibility of the sealant 340 and the first moisture barrier layer 350 being broken. The MEMS package structure 300 of the present embodiment provides a fourth weight protection through the molding compound 390.

Further, the moisture absorbing member 395 is disposed on the first substrate 360 and the second In the hole 362 surrounded by the substrate 370, even if moisture penetrates into the hole 362, it is absorbed by the moisture absorbing member 395 without entering the recess 332 to ensure that the MEMS element 320 can be normally operated. Working. In other words, the MEMS package structure 300 of the present embodiment provides a fifth weight guarantee through the moisture absorbing element 395.

In summary, the MEMS packaging structure of the present invention has a recess through the central portion of the cover plate, and the recess can be used for accommodating the MEMS component, reducing the gap height between the cover and the wafer, and transparently sealing The colloid is disposed in a gap between the cover plate and the wafer to seal the recess. Since the gap between the periphery of the cover plate and the wafer is small, the size of the sealant does not need to be too large, so that it is less likely to be cracked, so that the MEMS package structure of the present invention has better moisture resistance. In addition, the MEMS package structure of the present invention is coated around the wafer, the cover plate and the encapsulant through the first moisture barrier layer to prevent moisture from entering the recess and effectively providing the second weight protection. In addition, the MEMS package structure of the present invention further comprises disposing a wafer, a MEMS element, a cover plate, a sealant and a first moisture barrier layer in a hole surrounded by the first substrate and the second substrate, and borrowing A boundary region between the first substrate and the second substrate is sealed by the second moisture barrier layer to provide a third weight protection against moisture. Moreover, the MEMS package structure of the present invention provides a fourth weight protection against moisture by placing a molding compound in the cavity and adhering to the periphery of the first moisture barrier layer. Furthermore, the MEMS package structure of the present invention provides a fifth weight protection by arranging moisture absorbing elements in the holes to absorb moisture in the holes.

Although the present invention has been disclosed above by way of example, it is not intended to limit the present invention. The scope of the present invention is defined by the scope of the appended claims, which are defined by the scope of the appended claims. quasi.

D‧‧‧Distance

H‧‧‧ Height

100‧‧‧Microelectromechanical system package structure

110‧‧‧ wafer

112‧‧‧Active surface

120‧‧‧Microelectromechanical components

130‧‧‧ Cover

132‧‧‧ recesses

132a‧‧‧ upper surface

140‧‧‧ Sealant

150‧‧‧First moisture barrier

Claims (9)

A MEMS package structure includes: a wafer having an active surface; a MEMS element disposed on the active surface; a cover covering the wafer, the cover being integral and including a recess, wherein The microelectromechanical component is located in the recess; a gel is disposed between the wafer and the cover to seal the recess, wherein the sealant has a thickness smaller than a height of the microelectromechanical component; a first moisture barrier a layer covering the wafer, the encapsulant and the cover; a first substrate having a hole, wherein the wafer, the microelectromechanical component, the cover, the encapsulant and the first moisture barrier a layer is disposed in the hole; a second substrate disposed on the first substrate to cover the hole; and a second moisture barrier layer sealing a boundary region between the first substrate and the second substrate. The MEMS package structure of claim 1, further comprising: a molding compound disposed in the hole and sealed around the first moisture barrier layer. The MEMS package structure of claim 2, wherein a projection area of the molding compound on the first moisture barrier layer covers a projection of the encapsulant on the first moisture barrier layer region. The MEMS package structure of claim 1, further comprising: a moisture absorbing element disposed in the hole. The MEMS package structure of claim 1, wherein the second substrate has a region covering the encapsulant. The MEMS package structure of claim 1, wherein the recess has an upper surface relative to the active surface, the MEMS device comprising a mirror, a distance between the active surface and the upper surface Greater than the tilt height of the mirror. The MEMS package structure of claim 1, wherein the sealant has a thickness of between about 1 micrometer and 10 micrometers. The MEMS package structure of claim 1, wherein the MEMS element comprises a mirror, a switch, a capacitor, an accelerometer, an inductor or an actuator. The MEMS package structure of claim 1, wherein the material of the encapsulant comprises an epoxy resin.