TWI483892B - Micro-electromechanical device and method for manufacturing micro-electromechanical device - Google Patents

Description

Microelectromechanical device and method of manufacturing microelectromechanical device

The present invention relates to a microelectromechanical device and a method of fabricating the same.

With the advancement of semiconductor process technology, the development of microelectromechanical systems (MEMS) has been promoted. In the manufacturing method of the conventional micromechanical system, the active component process and the microelectromechanical process are performed separately, and after the active component circuit and the microelectromechanical device are respectively completed, the two are integrated on the same substrate to complete the MEMS system. The above manufacturing method is also called "System In Package" (SIP).

Another conventional manufacturing method is to form a microelectromechanical structure after forming semiconductor elements such as a metal oxide semiconductor device (MOS) and a bipolar junction transistor (BJT) in an active device circuit, and then A wafer level MEMS is completed by performing a metallization process of the active device circuit. The wafer is then diced into wafers (Die) and finally wafer packaged.

Regardless of the manufacturing method described above, in the manufacturing process of the microelectromechanical device, when the movable member of the microelectromechanical device is formed, it usually has to be completed by a grinding step. However, the grinding step is often accompanied by vibrations that cause some of the fine structures in the microelectromechanical device to be damaged. Moreover, in some MEMS devices, due to the overall configuration of the MEMS device, the spacing between the electrodes in some of the capacitor structures is too large, resulting in a decrease in capacitance, resulting in poor product performance.

Therefore, there is a need for a new MEMS device and manufacturing method that can improve the above problems.

One aspect of the present invention provides a microelectromechanical device. The MEMS device includes a substrate, a circuit layer, a microstructure, an elastic support member, a conductive layer, a through space, and a lower cover. The circuit layer is disposed on the upper surface of the substrate, and the circuit layer includes an active component and an inner connection pad. The active component is electrically connected to the inner connection pad. The through space penetrates the circuit layer and the substrate. The microstructure is received in the through space, and the microstructure includes a first electrode electrically connected to the active component. The elastic support member physically connects the circuit layer and the microstructure to suspend the microstructure in the through space. The conductive layer covers and seals the upper opening through the space. The conductive layer is disposed opposite to the microstructure, and a first gap exists therebetween, so that the conductive layer and the first electrode form a first capacitor structure. In addition, the conductive layer is electrically connected to the inner connection pad. The lower cover covers the lower opening of the through space, so that the lower cover and the conductive layer form a closed space surrounding the microstructure.

According to an embodiment of the invention, the microelectromechanical device further includes a second protective layer covering and contacting the conductive layer.

According to an embodiment of the invention, the MEMS device further includes an upper cover disposed above the conductive layer, and a second gap exists between the upper cover and the conductive layer.

According to an embodiment of the invention, the first gap in the microelectromechanical device has a width of from about 0.1 μm to about 10 μm.

According to an embodiment of the invention, the second gap in the microelectromechanical device has a width of from about 5 μm to about 100 μm.

According to an embodiment of the invention, the microstructure in the MEMS device further includes a second electrode, and the circuit layer further includes a third electrode, and the second electrode and the third electrode form a second capacitor structure.

Another aspect of the invention provides a method of making a microelectromechanical device. The method comprises: (a) forming a circuit layer on an upper surface of a substrate, the circuit layer comprising a microstructure having a first electrode: (b) forming a groove extending through the circuit layer and deep into the substrate to make the groove One of the bottoms is lower than the upper surface of the substrate, wherein the recess surrounds a portion of the periphery of the microstructure; (c) a sacrificial layer is formed on the circuit layer, wherein the sacrificial layer covers one of the upper surfaces of the microstructure and is filled in the recess (d) forming a conductive layer on the sacrificial layer such that the conductive layer forms a first capacitive structure with the first electrode; (e) removing a portion of the substrate from a side of the lower surface of the substrate to expose the sacrificial layer (f) removing the sacrificial layer to release the microstructure; and (g) arranging the cover under the substrate, the lower cover and the conductive layer forming a closed space surrounding the microstructure.

According to an embodiment of the present invention, the circuit layer of the step (a) further includes an active component, an inner connection pad, and a first protection layer, wherein the active component is electrically connected to the first electrode and the inner connection pad, and the first protection The layer is on one of the outer surfaces of the circuit layer and covers the inner connection pads.

According to an embodiment of the invention, step (a) includes forming a dielectric structure through the circuit layer and forming a metal structure surrounding the dielectric structure. In the present embodiment, step (b) includes sequentially removing the dielectric structure by dry etching and wet etching to remove the metal structure to expose the substrate; and removing a portion of the exposed substrate to form the recess.

According to an embodiment of the invention, step (c) includes forming an opening on the sacrificial layer, and the opening is substantially aligned with the inner connection pad to expose the first protective layer portion above the inner connection pad. In one embodiment, the method further includes removing the exposed first protective layer portion to expose the inner connection pad.

According to an embodiment of the invention, the vertical distance between the bottom of step (b) and the upper surface of the substrate is from about 5 μm to about 100 μm.

According to an embodiment of the invention, the sacrificial layer of step (c) is made of an organic photoresist material.

According to an embodiment of the invention, step (e) comprises: using a polishing process to remove portions of the substrate from one side of the lower surface of the substrate to expose the sacrificial layer.

According to an embodiment of the present invention, the step (e) comprises: using a grinding process to remove a portion of the substrate from a side of the lower surface of the substrate and etching the ground substrate by deep reactive ion etching to expose the sacrifice Floor.

According to an embodiment of the invention, step (f) removes the sacrificial layer with an oxygen plasma.

According to an embodiment of the invention, the method further includes: forming a second protective layer covering the conductive layer, wherein the second protective layer has a thickness of about 0.5 μm to about 10 μm.

According to an embodiment of the invention, the method further includes: configuring an upper cover to cover the conductive layer.

According to the microelectromechanical device and the method of manufacturing the same according to the embodiments of the present invention described above, the production yield, product stability, and product performance can be improved.

Please refer to FIG. 1A, which is a top view of a microelectromechanical device according to an embodiment of the present invention. 1A and 1B are illustrated by taking a microelectromechanical acceleration detector 100 as an example to facilitate understanding of the following disclosure of the present invention. The microelectromechanical device and the manufacturing method disclosed in the present invention can be applied to other products or fields, and thus the present invention is not limited to the microelectromechanical acceleration detector. The embodiments or the embodiments of the microelectromechanical device and the manufacturing method disclosed in the present invention may be combined or substituted with each other in an advantageous situation, and other embodiments may be added to an embodiment without further description or explanation. .

As shown in FIG. 1A, the microelectromechanical acceleration detector 100 mainly includes a movable microstructure 110, a semiconductor circuit 120, a plurality of external connection pads 130, and a circuit layer 140. The semiconductor circuit 120 is disposed substantially at the periphery of the movable microstructures 110. The outer connection pads 130 can generally be disposed on the periphery of the semiconductor circuit 120 for connection to an external circuit.

Referring to FIG. 1A, the circuit layer 140 has a through space 142 in which the microstructures 110 are housed. The microstructure includes a central portion 112, at least one resilient support member 114, and at least one second electrode 116. The elastic support member 114 connects the central portion 112 and the circuit layer 140 such that the central portion 112 is suspended in the through space 142 to assume a movable state. When an external force acts on the center portion 112, the center portion 112 can be displaced; when the external force disappears, the center portion 112 can be returned to the original position by the elastic force of the elastic support member 114. The width of the elastic support 114 can be, for example, from about 0.1 μm to about 10 μm. The second electrode 116 extends outwardly from the central portion 112 into the through space 142. In addition, the circuit layer 140 includes a third electrode 144 extending toward the through space 142 and forming a capacitor structure with the second electrode 116. The width of the second electrode 116 and the third electrode 144 may be, for example, about 0.1 μm to about 10 μm.

FIG. 1B is a cross-sectional view of the microelectromechanical acceleration detector 100 according to another embodiment of the present invention, which is substantially along line 3-3' of FIG. 1A. The movable microstructure 110 of the MEMS acceleration detector 100 is suspended in the through space 142 by an elastic support 114 similar to that shown in FIG. 1A. The microelectromechanical acceleration detector 100 also includes a conductive layer 390 disposed over the microstructures 110. The microstructure 110 has a first electrode 334 therein, and the first electrode 334 and the conductive layer 390 form a capacitor structure. The structure and features of the microelectromechanical device of one embodiment of the present invention will be described in more detail below.

When the MEMS acceleration detector 100 receives the acceleration in the y direction (as shown in FIG. 1A), the distance between the second electrode 116 and the third electrode 144 changes, and the capacitance value therebetween changes. Similarly, when the MEMS acceleration detector 100 is subjected to acceleration in the z direction (as shown in FIG. 1B), the distance between the first electrode 334 and the conductive layer 390 changes, and the capacitance value therebetween changes. The semiconductor circuit 120 measures the amount of change in the capacitance value or the capacitance value to estimate the acceleration of the MEMS acceleration detector 100 in various directions.

2 is a flow chart of a method 200 of fabricating a microelectromechanical device in accordance with an embodiment of the present invention. 3 to 16 are schematic cross-sectional views showing respective process stages in the manufacturing method of the embodiment of the present invention, which is roughly a schematic cross-sectional view of the line segment 3-3' in Fig. 1.

Step 210 is performed to form a circuit layer on the upper surface of the substrate. In one embodiment, as shown in FIG. 3A, circuit layer 320 includes active component 322, inner connection pads 324, and microstructures 330. The microstructure 330 has a first electrode 334 electrically connected to the active element 322. For example, the first electrode 334 can be electrically connected to the active component 322 via the elastic support 114 illustrated in FIG. 1 . The active component 322 can be, for example, a complementary metal oxide semiconductor device (CMOS) or a bipolar complementary metal oxide semiconductor device (BiCMOS). The inner connection pad 324 is located on the outer surface of the circuit layer 320 and is electrically connected to the active component 322. Substrate 310 can be, for example, a germanium wafer or other substrate suitable for use in fabricating semiconductor components.

In another embodiment, as shown in FIG. 3B, circuit layer 320 further includes feature structure 340 filled in region A. Feature structure 340 surrounds a portion of the perimeter of microstructure 330 and extends through circuit layer 320. In a subsequent step, feature structure 340 will be removed to form a portion of through space 142 depicted in FIGS. 1A and 1B. In other words, the feature structure 340 is pre-filled in the area A to be subsequently removed. In this embodiment, the circuit layer 320 further includes a first protective layer 326. The first protective layer 326 is located on the outer surface of the circuit layer 320 and covers the inner connection pads 324. The material of the first protective layer 326 may be, for example, ruthenium oxide.

Feature structure 340 includes a dielectric structure 342 and a metal structure 344. Dielectric structure 342 extends through circuit layer 320 and contacts underlying substrate 310. The dielectric structure 342 can be, for example, tantalum oxide or tantalum nitride, or a stack of tantalum oxide and tantalum nitride. Metal structure 344 also extends through circuit layer 320 and surrounds dielectric structure 342. In other words, the metal structure 344 is formed on the outer edge of the feature 340. In more detail, the metal structure 344 can comprise two portions 344a and 344b. The portion 344a of the metal structure physically connects the circuit layer 320 with the dielectric structure 342; the portion 344b of the metal structure physically connects the microstructure 330 with the dielectric structure 342.

In embodiments in which the circuit layer 320 described above includes features 340, the step of forming the circuit layer 320 includes forming a CMOS or BiCMOS process. In the standard process of CMOS components, it can include four metallization processes and two polysiliconization processes (2P4M process), and can also include five metallization processes and one polysiliconization process (5M1P process). Thus, in an embodiment, when CMOS component 322 is formed, feature 340 can be formed simultaneously by a suitable reticle design. For example, when forming a dielectric layer in CMOS device 322, dielectric structure 342 of feature structure 340 can be formed simultaneously. When the conductive layer of CMOS element 322 is formed, portions of metal structure 344 in feature structure 340 can be formed simultaneously. When the metal is filled in the via of the CMOS device, a portion of the metal structure 344 can be formed simultaneously. Therefore, the feature structure 340 can be formed step by step while forming the CMOS element 322. In one embodiment, the metal filled in the via of the CMOS device is tungsten, and the conductive layer of the CMOS device 322 is aluminum. Therefore, the metal structure 344 can be formed by stacking an aluminum layer and a tungsten layer. That is, the metal structure 344 can be a multi-layer structure and composed of at least two metal materials.

In step 220, a recess 312 is formed through the circuit layer 320 and into the substrate 310, as shown in FIG. The bottom 312b of the recess 312 is lower than the upper surface 310a of the substrate, and the recess 312 surrounds a portion of the perimeter of the microstructure 330. In a subsequent step, the recess 312 will form a portion of the through space 142 depicted in Figures 1A and 1B. Two embodiments of forming the recess 312 will be exemplarily described below.

In one embodiment, the dielectric material in the circuit layer 320 can be removed by exposure, development, and reactive ion etching (RIE), and the opening B shown in FIG. 4A is formed in the circuit layer 320, and The substrate 310 in the opening B is exposed. Next, a portion of the exposed substrate 310 is removed by, for example, Deep Reactive Ion Etching (DRIE) to form a recess 312 as shown in FIG.

In an embodiment in which the circuit layer 320 includes the features 340, a photoresist layer 350 is formed over the circuit layer 320 and the microstructures 330, as shown in FIG. 4B. The photoresist layer 350 has an opening 352 to expose the features 340. Next, the dielectric structure 342 is removed by a dry etching method such as reactive ion etching (RIE) as shown in FIG. 4C. Reactive ion etching only etches dielectric materials such as hafnium oxide and tantalum nitride without etching the metal material. During the reactive ion etching process, since the sidewalls of the microstructure 330 and the sidewalls of the circuit layer 320 are covered by the metal structure 344, the reactive ion etching does not damage or etch the sidewalls of the microstructure 330 and the circuit layer 320. The sidewalls of the microstructures 330 and circuit layers 320 maintain their original contoured appearance. Subsequently, the metal structure 344 is removed by wet etching as shown in FIG. 4D. After the metal structure 344 is removed, the opening B shown in FIG. 4D is formed in the circuit layer 320, and the substrate 310 in the opening B is exposed. The etchant employed in the wet etching has a high etching selectivity for the metal material and the oxide material (or nitride), for example, higher than 15:1 or higher than 20:1 or higher than 30:1 or higher. Therefore, when the metal structure 344 is removed, the original sidewall profile appearance of the microstructure 330 and the circuit layer 320 is hardly impaired. For example, the etchant contains sulfuric acid and hydrogen peroxide, and the weight ratio of sulfuric acid to hydrogen peroxide is about 2:1. Of course, other commercially available metal etchants are also suitable for use in the present invention. Finally, a portion of the exposed substrate 310 is removed by, for example, Deep Reactive Ion Etching (DRIE) to form a recess 312 as shown in FIG. In the above embodiment, the angle θ between the sidewall of the microstructure 330 and the upper surface of the substrate 310 may be from about 85 degrees to about 95 degrees. In addition, the surface of the sidewalls of the microstructures 330 and the sidewalls of the circuit layer 320 are flat, which helps to improve the performance of the microelectromechanical device and the stability of the product quality.

In one embodiment, the vertical distance d between the bottom 312b of the recess 312 and the upper surface 310a of the substrate 310 is from about 5 μm to about 100 μm, as shown in FIG.

In step 230, a sacrificial layer 360 is formed over circuit layer 320, as shown in FIG. The sacrificial layer 360 covers the upper surface 332 of the microstructure 330 and is filled within the recess 312. The sacrificial layer 360 can be made, for example, of a polymer material. For example, the sacrificial layer 360 can be a photoresist material that is patterned to cover the microstructures 330 and fill the recesses 312. The material of the sacrificial layer 360 may be, for example, a phenol resin type photoresist, an acrylic type photoresist or other organic material.

In embodiments in which the circuit layer 320 includes the inner connection pads 324 and the first protective layer 326, the sacrificial layer 360 has an opening 362, and the opening 360 is substantially aligned with the connection pads 324 to expose portions above the inner connection pads 324. The first protective layer 326. In this embodiment, the exposed first protective layer portion 326 can be successively removed to expose the inner connection pads 324 as shown in FIG.

In step 240, a conductive layer 390 is formed on the sacrificial layer 360 such that the conductive layer 390 forms a first capacitive structure with the first electrode 334, as shown in FIG. In one embodiment, the conductive layer is formed by depositing a conductive layer by a sputtering process, followed by photoresist coating, exposure, development, and etching of the patterned conductive layer. Subsequently, a photoresist stripping process is performed to remove the photoresist on the conductive layer 390. In this embodiment, the sacrificial layer 360 is a photoresist material, so when the photoresist process is performed, the sacrificial layer 360 not covered by the conductive layer 390 will be removed together (for example, the sacrificial layer 360a shown in FIG. 6 Part and 360b part). In an embodiment in which the circuit layer 320 includes the inner connection pads 324, the conductive layer 390 is connected to and in contact with the inner connection pads 324 such that the conductive layer 390 can be electrically connected to the active elements 322 by the inner connection pads 324. Therefore, the capacitance value of the first capacitor structure formed between the conductive layer 390 and the first electrode 334 can be measured by the active component 322. The thickness of the conductive layer 390 can be, for example, from about 0.5 μm to about 10 μm. The conductive layer 390 can be made of, for example, a metal material such as gold, silver, aluminum, or copper or polycrystalline germanium.

In another embodiment, after the conductive layer 390 is formed, a second protective layer 392 may be formed to cover the conductive layer 390, as shown in FIG. In an embodiment, the second protective layer 392 is located on the conductive layer 390 and the upper surface of the circuit layer. In embodiments where circuit layer 320 includes a first protective layer 326, a second protective layer 392 is formed over conductive layer 390 and first protective layer 326. The second protective layer 392 can be made, for example, of tantalum nitride or hafnium oxide. The thickness of the second protective layer 392 may be, for example, about 0.5 μm to about 10 μm. The second protective layer 392 serves to protect the underlying conductive layer 390, and after the step of subsequently removing the sacrificial layer 360, the second protective layer 392 helps to increase the mechanical strength of the conductive layer 390.

In still another embodiment, after the second protective layer 392 is formed, the upper cover 370 is disposed above the circuit layer 320, so that the upper cover 370 covers the conductive layer 390, as shown in FIG. The upper cover 370 is used to protect the finally formed microelectromechanical device, and the upper cover 370 can be made, for example, of a glass or tantalum substrate. In an embodiment, the upper cover 370 can be fixed above the circuit layer 320 by an adhesive layer 372.

In step 250, portions of the substrate 310 are removed from the side of the lower surface 310b of the substrate 310 to expose the sacrificial layer 360, as shown in FIG. In one embodiment, the lower surface 310b of the substrate 310 may be first ground to reduce the thickness of the substrate 310 to a certain thickness, such as grinding the thickness of the substrate 310 to about 150 [mu]m. Subsequently, the lower surface of the substrate 310 is etched by DRIE to form a recess 314 on the lower surface of the substrate 310. The depth of the recess 314 is sufficient to expose the sacrificial layer 360, as shown in FIG. In other embodiments, the lower surface of the substrate 310 can be directly polished until the sacrificial layer is exposed without etching using DRIE.

In the prior art, when the lower surface of the substrate is ground, vibration is often accompanied, and the fine structure in the microstructure is damaged by vibration. For example, the elastic support member 114 or the electrodes 116, 144 shown in Fig. 1 are typically only about 0.1 μm to about 10 μm wide and are easily damaged by vibration. In the embodiment of the present invention, after the recess 312 is formed, the sacrificial layer 360 is filled in the recess 312, which can effectively prevent the microstructure from being damaged by vibration. In addition, filling the sacrificial layer 360 in the recess 312 also prevents the adhesive layer 372 or other contaminants from entering the recess 312 when step 240 is performed. Thus, according to an embodiment of the present invention, the yield of the microelectromechanical device can be effectively improved.

In step 260, the sacrificial layer 360 is removed to release the microstructures 330, as shown in FIG. In one embodiment, the sacrificial layer 360 can be removed using oxygen plasma to form a through space 316. A first gap h is formed between the microstructures 330 and the conductive layer 390. In one embodiment, the gap width h between the conductive layer 390 and the microstructures 330 is from about 0.1 μm to about 5 μm, more specifically from about 0.1 μm to about 2 μm. In other embodiments, other chemical solvents may be utilized to remove the sacrificial layer 360. In other words, the method of removing the sacrificial layer 360 can be changed or adjusted depending on the material properties or process requirements of the sacrificial layer 360. As used herein, "releasing microstructure" means causing a microelectromechanical device to produce a structure or component that is relatively movable. Specifically, after the sacrificial layer 360 is removed, the microstructures 330 are suspended in the through space 316 by elastic supports (not shown in FIG. 12 ), and thus the microstructures 330 can be displaced relative to the circuit layers 320 .

In step 270, the lower cover 380 is disposed below the substrate 310 to form the microelectromechanical device 300, as shown in FIG. The lower cover 380 and the conductive layer 390 form a closed space C surrounding the microstructures 330. The microstructures 330 can be relatively displaced in the enclosed space C to cause the microelectromechanical device to produce a predetermined function. The upper cover 370 and the lower cover 380 are used to protect the microstructures 330. The material of the lower cover 380 may be the same as or different from the upper cover 370. In an embodiment, the lower cover 380 can be fixed under the substrate 310 by an adhesive layer 382.

It can be seen from the above embodiment that after the sacrificial layer 360 is formed, the conductive layer 390 is formed over the sacrificial layer 360, so that the first gap h between the conductive layer 390 and the microstructure 330 can be controlled by controlling the thickness of the sacrificial layer 360. width. According to an embodiment of the present invention, the distance between the conductive layer 390 and the first electrode 334 can be well controlled. In other words, the capacitance value between the conductive layer 390 and the first electrode 334 can be precisely controlled, thereby improving product stability. On the other hand, when the distance between the conductive layer 390 and the first electrode 334 is reduced, the capacitance value between the conductive layer 390 and the first electrode 334 is increased, which also contributes to the performance of the product.

By providing another embodiment of the present invention, a microelectromechanical device 300 is provided, as shown in FIG. The microelectromechanical device 300 includes a substrate 310, a circuit layer 320, a microstructure 330, a conductive layer 390, a through space 316, a lower cover 380, and an elastic support member (not shown in FIG. 12). The circuit layer 320 is disposed on the upper surface of the substrate 310, and the circuit layer 320 includes an active component 322 and an inner connection pad 324. The active component 322 is electrically connected to the inner connection pad 324. The through space 316 extends through the circuit layer 320 and the substrate 310. The microstructures 330 are received in the through space 316, and the microstructures 330 include a first electrode 334 electrically connected to the active component 322. The elastic support physically connects the circuit layer 320 and the microstructures 330 such that the microstructures 330 are suspended in the through space 316. Conductive layer 390 covers and seals the upper opening through space 316. The conductive layer 390 is disposed opposite to the microstructure 330, and a first gap h exists therebetween, so that the conductive layer 390 and the first electrode 334 form a first capacitor structure. In addition, the conductive layer 390 is electrically connected to the inner connection pad 324. The lower cover covers the lower opening of the through space 316, so that the lower cover 380 and the conductive layer 390 form a closed space C surrounding the microstructures 330.

In an embodiment, the MEMS device 300 further includes a second protective layer 392 and an upper cover 370. The second protective layer 392 covers and contacts the conductive layer 390. The upper cover 370 is located above the second protective layer 392, and a second gap g exists between the upper cover and the second protective layer 392. In an embodiment, the first gap h has a width of from about 0.1 μm to about 10 μm. In another embodiment, the second gap g is from about 5 [mu]m to about 100 [mu]m wide.

In another embodiment, as shown in FIG. 1A, the microstructure 110 further includes a second electrode 116, and the circuit layer further includes a third electrode 144. The second electrode 116 and the third electrode 144 are located in the through space, and the second electrode 116 and the third electrode 144 form a second capacitor structure.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100. . . MEMS acceleration detector

110. . . microstructure

112. . . Central department

114. . . Elastic support

116. . . Second electrode

120. . . Semiconductor circuit

130. . . Outer connection pad

140. . . Substrate

142. . . Through space

144. . . Third electrode

200. . . method

210, 220, 230, 240, 250, 260, 270. . . step

300. . . Microelectromechanical device

310. . . Substrate

310a. . . Upper surface

310b. . . lower surface

312. . . Groove

312b. . . bottom

314. . . Depression

316. . . Through space

320. . . Circuit layer

322. . . Active component

324. . . Inner connection pad

326. . . First protective layer

330. . . microstructure

332. . . Upper surface

334. . . First electrode

340. . . Feature structure

342. . . Dielectric structure

344. . . Metal structure

350. . . Photoresist layer

352. . . Opening

360. . . Sacrificial layer

362. . . Opening

370. . . Upper cover

372. . . Adhesive layer

380. . . Lower cover

382. . . Adhesive layer

390. . . Conductive layer

392. . . Second protective layer

A. . . region

B. . . Opening

C. . . Closed space

d. . . distance

θ. . . Angle

h. . . First gap

g. . . Second gap

1A is a top plan view showing a microelectromechanical device according to an embodiment of the present invention.

1B is a cross-sectional view showing a microelectromechanical device according to another embodiment of the present invention.

2 is a flow chart showing a method of manufacturing a microelectromechanical device according to an embodiment of the present invention.

3A to 12 are schematic cross-sectional views showing respective process stages in the method of fabricating a microelectromechanical device according to an embodiment of the present invention.

200. . . method

210, 220, 230, 240, 250, 260, 270. . . step

Claims (19)

A method of fabricating a microelectromechanical device, comprising: (a) forming a circuit layer on an upper surface of a substrate, the circuit layer comprising a microstructure having a first electrode: (b) forming a recess therethrough a circuit layer and deep into the substrate such that a bottom of the recess is lower than an upper surface of the substrate, wherein the recess surrounds a portion of the periphery of the microstructure; (c) forming a sacrificial layer on the circuit layer, Wherein the sacrificial layer covers an upper surface of the microstructure and is filled in the recess; (d) forming a conductive layer on the sacrificial layer to form a first capacitor structure between the conductive layer and the first electrode; (e) removing a portion of the substrate from a side of the lower surface of the substrate to expose the sacrificial layer; (f) removing the sacrificial layer to release the microstructure; and (g) arranging the cover Below the substrate, the lower cover and the conductive layer form a closed space surrounding the microstructure. The method of claim 1, wherein the circuit layer of the step (a) further comprises an active component, an inner connecting pad and a first protective layer, wherein the active component is electrically connected to the first electrode and the inner connecting a pad, and the first protective layer is located on an outer surface of the circuit layer and covers the inner connection pad. The method of claim 2, wherein the step (a) comprises: forming a dielectric structure through the circuit layer and forming a metal structure ring Wrap the dielectric structure; and wherein step (b) comprises: sequentially removing the dielectric structure by dry etching and wet etching to remove the metal structure to expose the substrate; and removing a portion of the exposed substrate To form the groove. The method of claim 3, further comprising: forming an opening on the sacrificial layer, and the opening is aligned with the inner connecting pad to expose the first protective layer portion above the inner connecting pad. The method of claim 4, further comprising: removing the exposed first protective layer portion to expose the inner connection pad. The method of claim 5, wherein the conductive layer contacts the inner connection pad. The method of claim 1, wherein a vertical distance between the bottom of the step (b) and the upper surface of the substrate is from about 5 μm to about 100 μm. The method of claim 1, wherein the sacrificial layer of the step (c) is an organic photoresist material. The method of claim 1, wherein the step (e) comprises: removing a portion of the substrate from a side of the lower surface of the substrate using a polishing process to expose the sacrificial layer. The method of claim 1, wherein the step (e) comprises: using a polishing process to remove a portion of the substrate from a side of the lower surface of the substrate; and etching the ground substrate by deep reactive ion etching To expose the sacrificial layer. The method of claim 1, wherein the step (f) removes the sacrificial layer with an oxygen plasma. The method of claim 1, further comprising: forming a second protective layer covering the conductive layer, wherein the second protective layer has a thickness of about 0.5 μm to about 10 μm. The method of claim 1, further comprising: configuring an upper cover to cover the conductive layer. A microelectromechanical device comprising: a substrate; a circuit layer formed on an upper surface of the substrate, the circuit layer comprising an active component and an inner connecting pad electrically connecting the active component; a penetrating space, through the circuit layer and the substrate; a microstructure, is received in the through space, and the microstructure comprises a first electrode electrically connected to the active component; an elastic support member, a physical connection The circuit layer and the microstructure structure suspend the microstructure in the through space; a conductive layer covers and seals an opening in one of the through spaces, and a first gap exists between the conductive layer and the microstructure The conductive layer and the first electrode form a first capacitor structure, and the conductive layer is electrically connected to the inner connecting pad; and the lower cover covers an opening of the through space, and the lower cover and the conductive layer A closed space is formed around the microstructure. The MEMS device of claim 14, further comprising a second protective layer covering and contacting the conductive layer. The MEMS device of claim 14, further comprising an upper cover disposed above the conductive layer, and a second gap between the upper cover and the conductive layer. The MEMS device of claim 16, wherein the second gap has a width of from about 5 μm to about 100 μm. The MEMS device of claim 14, wherein the first gap has a width of from about 0.1 μm to about 10 μm. The MEMS device of claim 14, wherein the microstructure further comprises a second electrode, and the circuit layer further comprises a third electrode, the second electrode and the third electrode are located in the through space, and are formed A second capacitor structure.