TWI876304B - Pressure sensing module and manufacturing method thereof - Google Patents

Abstract

A pressure sensing module includes a substrate and a sensing layer. The substrate has a first surface and a second surface opposite to each other. The substrate includes a stepped cavity and an opening. The stepped cavity extends from the first surface to the second surface, the opening extends from the second surface to the first surface, and the stepped cavity communicates with the opening. The sensing layer is disposed on the first surface of the substrate and covers the first surface of the substrate. The sensing layer includes at least one sensing element and a cross-shaped structure. The cross-shaped structure includes a central portion and a plurality of extending portions connecting the central portion. The central portion and the extension portions respectively include at least one hollow portion. An orthographic projection of the central portion of the cross-shaped structure on the substrate overlaps with the opening of the substrate.

Description

Pressure sensing module and manufacturing method thereof

The present invention relates to a sensing module and a manufacturing method thereof, and in particular to a pressure sensing module and a manufacturing method thereof.

Piezoresistive (piezo-resistive) micromechanical system (MEMs) pressure sensors are used to convert pressure into corresponding electronic signals. Generally speaking, a piezo-resistive MEMS pressure sensor includes a flexible sensing film having at least one sensing element disposed in the sensing film. By measuring the change in resistance caused by the pressure applied to the sensing film, the sensing film can be used to measure the applied pressure. In the current manufacturing process of piezo-resistive MEMS pressure sensors, the thickness of the sensing film is controlled by back-side wet etching, and the etching depth is controlled by the time of immersion in the liquid. However, this manufacturing method makes it difficult to control the film thickness, and therefore the manufacturing process is relatively difficult.

The "prior art" section is only used to help understand the content of the present invention. Therefore, the content disclosed in the "prior art" section may contain some content that does not constitute the common knowledge of the person skilled in the art. The content disclosed in the "prior art" section does not mean that the content or the problem to be solved by one or more embodiments of the present invention has been known or recognized by the person skilled in the art before the application of the present invention.

The present invention provides a pressure sensing module, which has better sensing sensitivity and can improve the pressure tolerance (Burst Pressure).

The present invention also provides a method for manufacturing a pressure sensing module, which is used to manufacture the pressure sensing module and has the advantages of simple manufacturing process and high yield.

Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

In order to achieve one or part or all of the above-mentioned purposes or other purposes, an embodiment of the present invention proposes a pressure sensing module, including a substrate and a sensing layer. The substrate has a first surface and a second surface opposite to each other. The substrate includes a stepped groove and an opening. The stepped groove extends from the first surface to the second surface, and the opening extends from the second surface to the first surface, and the stepped groove is connected to the opening. The sensing layer is arranged on the first surface of the substrate and covers the first surface of the substrate. The sensing layer includes at least one sensing element and a cross-shaped structure. The cross-shaped structure includes a central portion and a plurality of extension portions connected to the central portion. The central portion and the extension portion each include at least one hollow portion. The orthographic projection of the central portion of the cross-shaped structure on the substrate overlaps with the opening of the substrate.

In one embodiment of the present invention, the stepped groove includes a first annular groove and a second annular groove. The first annular groove is located between the opening and the second annular groove. The diameter of the first annular groove is smaller than the diameter of the second annular groove and larger than the diameter of the opening.

In an embodiment of the present invention, the pressure sensing module further includes a protective layer disposed on the sensing layer to cover at least one sensing element and the cross-shaped structure.

In one embodiment of the present invention, the material of the protective layer includes silicon nitride.

In an embodiment of the present invention, the pressure sensing module further includes a cover plate disposed on the protective layer. The cover plate includes a first portion and a second portion surrounding the first portion. The first portion corresponds to at least a portion of the cross-shaped structure, and the second portion is connected to the protective layer.

In one embodiment of the present invention, the material of the cover plate is the same as that of the substrate.

In one embodiment of the present invention, the substrate is a cavity-semiconductor-on-insulator (C-SOI) substrate.

In one embodiment of the present invention, the sensing layer further includes a first oxide layer, a second oxide layer, an active layer and a patterned metal layer. The active layer is located between the first oxide layer and the second oxide layer. The second oxide layer is disposed on the first surface of the substrate. At least one sensing element is buried in the active layer. At least one hollow portion penetrates a portion of the first oxide layer and the active layer. The patterned metal layer is disposed on at least one of the first oxide layer and the active layer.

In an embodiment of the present invention, the cross-shaped structure is in a double-rib or grid shape.

In one embodiment of the present invention, the at least one sensing element comprises at least one piezoresistive sensor.

To achieve one or part or all of the above purposes or other purposes, an embodiment of the present invention proposes a method for manufacturing a pressure sensing module, which includes the following steps. A first annular groove is formed on a substrate to define at least one supporting structure on the substrate. The substrate has a first surface and a second surface opposite to each other. The first annular groove extends from the first surface to the second surface and surrounds at least one supporting structure. A second annular groove is formed on the substrate. The second annular groove extends from the first surface to the second surface and connects to the first annular groove. The second annular groove and the first annular groove define a stepped groove. A sensing layer is formed on the substrate. The sensing layer covers the first surface of the substrate. The sensing layer includes at least one sensing element. A cross-shaped structure is formed on the sensing layer. The cross-shaped structure includes a central portion and a plurality of extensions connected to the central portion. The central portion and the extensions each include at least one hollow portion. A portion of the substrate and at least one supporting structure are removed from the second surface of the substrate toward the first surface to form an opening connected to the stepped groove. The orthographic projection of the central portion of the cross-shaped structure on the substrate overlaps with the opening.

In an embodiment of the present invention, the manufacturing method of the pressure sensing module further includes forming a protective layer on the sensing layer to cover at least one sensing element and the cross-shaped structure.

In an embodiment of the present invention, the manufacturing method of the pressure sensing module further includes bonding a cover plate to the protective layer. The cover plate includes a first portion and a second portion surrounding the first portion. The first portion corresponds to at least a portion of the cross-shaped structure, and the second portion is bonded to the protective layer.

In one embodiment of the present invention, the manufacturing method of the pressure sensing module further includes forming a third groove on the cover plate. The third groove extends from a third surface to a fourth surface. Forming a fourth groove on the cover plate. The fourth groove extends from the third surface to the fourth surface and connects to the third groove to define the first portion. After joining the second portion of the cover plate to the protective layer, a portion of the cover plate is removed from the fourth surface of the cover plate toward the third surface.

In one embodiment of the present invention, the step of forming the first annular groove on the substrate includes: depositing an oxide layer on the first surface of the substrate. The oxide layer covers a portion of the first surface of the substrate. Forming a photoresist layer on the first surface of the substrate. The photoresist layer covers the oxide layer and a portion of the first surface not covered by the oxide layer. Using the photoresist layer as a mask, etching the first surface of the substrate not covered by the photoresist layer to form the first annular groove.

In one embodiment of the present invention, the step of forming the second annular groove on the substrate includes: removing the photoresist layer to expose the oxide layer and a portion of the first surface of the substrate not covered by the oxide layer, and performing a dry etching process on the first surface of the substrate to form the second annular groove.

In one embodiment of the present invention, the step of forming a sensing layer on a substrate includes: bonding a wafer and disposing a first oxide layer and a second oxide layer on the substrate, wherein the first oxide layer and the second oxide layer are located on opposite sides of the wafer. Removing the first oxide layer and a portion of the wafer to form an active layer. Forming at least one sensing element in the active layer. Disposing a third oxide layer on the active layer and the at least one sensing element. Forming a patterned metal layer on the third oxide layer. Forming at least one hollow portion to penetrate the third oxide layer and a portion of the active layer to define a cross-shaped structure.

In an embodiment of the present invention, the method of forming at least one hollow portion includes a dry etching method or a front wet etching method.

In an embodiment of the present invention, the shape of the at least one supporting structure includes at least one of a circle, a rectangle and a cross.

Based on the above, the embodiments of the present invention have at least one of the following advantages or effects. In the design of the pressure sensing module of the present invention, the sensing layer includes a cross-shaped structure, and the central portion and the extension portion of the cross-shaped structure each include at least one hollow portion. Therefore, in addition to having better structural symmetry, the sensing layer of the present invention can also reduce the rigidity of the sensing layer through the hollow portion to improve the sensing sensitivity. In addition, the substrate of the present invention has a stepped groove design. When the sensing layer is deformed by a pressure exceeding the operating range, the sensing layer will top the stepped groove below. If the pressure continues to increase, the deformation area of the sensing layer will become smaller, and the pressure tolerance (Burst Pressure) will increase. Therefore, the pressure sensing module of the present invention has better sensing sensitivity and can improve the pressure tolerance.

The above-mentioned other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and are not used to limit the present invention.

Fig. 1A to Fig. 1G are schematic cross-sectional views of a method for manufacturing a pressure sensing module according to an embodiment of the present invention. Fig. 2A to Fig. 2C are schematic top views of Fig. 1A. Fig. 2D is a schematic top view of Fig. 1F. Fig. 3 is a schematic cross-sectional view of applying pressure to Fig. 1G. Fig. 4A is a schematic cross-sectional view of a partial step of a method for manufacturing a pressure sensing module according to another embodiment of the present invention. Fig. 4B is a schematic top view of Fig. 4A. Fig. 5A is a schematic cross-sectional view of a partial step of a method for manufacturing a pressure sensing module according to another embodiment of the present invention. Fig. 5B is a schematic top view of Fig. 5A.

It should be noted that FIG. 1A is a schematic cross-sectional view along line I-I of FIG. 2A ; FIG. 1F is a schematic cross-sectional view along line II-II of FIG. 2D ; FIG. 4A is a schematic cross-sectional view along line III-III of FIG. 4B ; FIG. 5A is a schematic cross-sectional view along line IV-IV of FIG. 5B ; and FIG. 6D is a schematic cross-sectional view along line V-V of FIG. 6E . For the sake of clarity, FIG. 2A , FIG. 2B , and FIG. 2C omit the oxide layer and the photoresist layer in FIG. 1A , and FIG. 4B omits the oxide layer and the photoresist layer in FIG. 4A .

Please refer to FIG. 1A and FIG. 2A at the same time. According to the manufacturing method of the pressure sensing module of the present embodiment, first, a first annular groove 111a is formed on the substrate 110a to define at least one supporting structure (schematically showing a supporting structure 113a) on the substrate 110a. In detail, the substrate 110a has a first surface S1 and a second surface S2 opposite to each other. The substrate 110a is, for example, a silicon substrate. The steps of forming the first annular groove 111a on the substrate 110a are as follows. First, an oxide layer 10 is deposited on the first surface S1 of the substrate 110a, wherein the oxide layer 10 covers a portion of the first surface S1 of the substrate 110a. The oxide layer 10 is, for example, a silicon dioxide (SiO ₂ ) layer. Next, a photoresist layer 20 is formed on the first surface S1 of the substrate 110a, wherein the photoresist layer 20 covers the oxide layer 10 and a portion of the first surface S1 not covered by the oxide layer 10. At this time, the area on the first surface S1 not covered by the photoresist layer 20 is the area where the first annular groove 111a is to be formed, that is, the oxide layer 10 and the photoresist layer 20 cover the remaining portion of the first surface S1, and a portion of the photoresist layer 20 is located on the oxide layer 10. Afterwards, the first surface S1 of the substrate 110a not covered by the photoresist layer 20 is etched using the photoresist layer 20 as a mask to form the first annular groove 111a. As shown in FIG. 1A , the first annular groove 111 a extends from the first surface S1 to the second surface S2 and surrounds the supporting structure 113 a .

As shown in FIG2A , the shape of the supporting structure 113a may be, for example, a rectangle. In other embodiments, please refer to FIG2B , the shape of the supporting structure 113b may be, for example, a circle; or, please refer to FIG2C , the shape of the supporting structure 113c may be, for example, a cross. The above-mentioned supporting structures 113a, 113b, and 113c are only schematically shown as one, but are not limited to this. In another embodiment, please refer to FIG4A and FIG4B at the same time, the shape of the supporting structure 113d may be, for example, a circle, and the number of supporting structures 113d may be multiple, such as four, but is not limited to this. The shapes of the supporting structures 113a, 113b, 113c, and 113d of this embodiment include at least one of a circle, a rectangle, and a cross. The support structures 113a, 113b, 113c, and 113d are provided to improve the process yield.

Next, please refer to FIG. 1A and FIG. 1B at the same time, remove the photoresist layer 20 to expose the oxide layer 10 and a portion of the first surface S1 of the substrate 110a that is not covered by the oxide layer 10. At this time, the area on the first surface S1 that is not covered by the oxide layer 10 is the area where the second annular groove 115a is to be formed. Afterwards, a dry etching process is performed on the first surface S1 of the substrate 110a to form the second annular groove 115a on the substrate 110a. The second annular groove 115a extends from the first surface S1 to the second surface S2 and is connected to the first annular groove 111a. The second annular groove 115a and the first annular groove 111a define a stepped groove SC. In one embodiment, the depth T of the second annular groove 115a can be, for example, 3 microns.

Next, please refer to FIG. 1B, FIG. 1F and FIG. 1C simultaneously, remove the oxide layer 10, and form a sensing layer 120a on the substrate 110a. The steps of forming the sensing layer 120a on the substrate 110a are as follows. First, please refer to FIG. 1C, bond the wafer W and configure the first oxide layer 30 and the second oxide layer 40 on the substrate 110a, wherein the first oxide layer 30 and the second oxide layer 40 are located on opposite sides of the wafer W, and the second oxide layer 40 directly contacts the first surface S1 of the substrate 110a. The first oxide layer 30 and the second oxide layer 40 can be, for example, silicon dioxide ( _SiO2 ) layers, respectively. The wafer W is, for example, a silicon wafer. At this point, a semiconductor-on-insulator (SOI) substrate has been formed.

Next, please refer to FIG. 1C and FIG. 1D , the first oxide layer 30 and a portion of the wafer W are removed to form an active layer 50. Here, the method of removing the first oxide layer 30 and a portion of the wafer W is, for example, through grinding.

Next, referring to FIG. 1E , at least one sensing element (two sensing elements 122a are schematically shown) is formed in the active layer 50. Here, the sensing element 122a is, for example, a piezoresistive sensor. Next, a third oxide layer 60 is disposed on the active layer 50 and the sensing element 122a, and a fourth oxide layer 70 is disposed on the second surface S2 of the substrate 110a. The third oxide layer 60 and the fourth oxide layer 70 can be, for example, silicon dioxide (SiO ₂ ) layers, respectively. Next, a patterned metal layer 124a is formed on the third oxide layer 60, wherein a portion of the patterned metal layer 124a can directly contact the active layer 50 and extend onto the third oxide layer 60. Here, the material of the patterned metal layer 124a is, for example, aluminum copper (AlCu), but is not limited thereto.

Afterwards, please refer to FIG. 1F and FIG. 2D at the same time, at least one hollow portion (schematically showing a plurality of hollow portions 125a) is formed to penetrate the third oxide layer 60 and a portion of the active layer 50, thereby defining a cross-shaped structure 126a. Here, the method of forming the hollow portion 125a is, for example, dry etching or front wet etching from the first surface S1 of the substrate 110a to the second surface S2. At this point, the cross-shaped structure 126a has been formed on the sensing layer 120a, and the manufacturing of the sensing layer 120a is completed. In short, the present embodiment forms the sensing layer 120a by grinding and dry etching or front wet etching. Compared with the prior art of forming the sensing film by backside wet etching, the present embodiment can effectively control the thickness, thereby improving the process yield and the sensing sensitivity of the sensing layer 120a.

As shown in FIG. 1F and FIG. 2D , the sensing layer 120a of the present embodiment covers the first surface S1 of the substrate 110a, and the sensing layer 120a includes a sensing element 122a, a patterned metal layer 124a, a cross-shaped structure 126a, a second oxide layer 40, an active layer 50, and a third oxide layer 60. The cross-shaped structure 126a includes a central portion 127a and a plurality of extension portions (four extension portions 129a are schematically shown) connected to the central portion 127a, wherein the central portion 127a and the extension portion 129a each include a hollow portion 125a. Here, the cross-shaped structure 126a is, for example, in a double rib shape.

In another embodiment, please refer to FIG. 5A and FIG. 5B simultaneously, the cross-shaped structure 126b of the sensing layer 120b includes a central portion 127b and a plurality of extension portions (four extension portions 129b are schematically shown) connected to the central portion 127b, wherein the central portion 127b and the extension portions 129b respectively include a plurality of hollow portions 125b. In one embodiment, the central portion 127b may include, for example, nine hollow portions 125b, and each extension portion 129b may include, for example, three hollow portions 125b, but the present invention is not limited thereto. Here, the cross-shaped structure 126b may be, for example, in a grid shape.

It should be noted that the hollow portions 125a and 125b are provided to form hollow double rib-shaped or grid-shaped cross structures 126a and 126b, wherein the number of rib-shaped/grid-shaped structures may be N, and N is limited by the relationship between process capability and film size. Taking FIG. 2D as an example, the number N of rib-shaped structures of the double rib-shaped cross structure 126a is 2. Taking FIG. 5B as an example, the number N of grid-shaped structures of the grid-shaped cross structure 126b is 4. By designing the hollow portions 125a and 125b to reduce the width of each rib-shaped/grid-shaped structure and increase the distance between the rib-shaped/grid-shaped structures, the rigidity and elastic coefficient of the sensing layers 120a and 120b can be reduced, and the sensitivity can be improved. In addition, by connecting multiple rib-shaped/grid-shaped structures to each other, the toughness of the sensing layers 120a and 120b can be enhanced, thereby improving the tolerance of process variation and the safety factor, and having a higher burst pressure.

Next, please refer to FIG. 1G , a protective layer 130 is formed on the sensing layer 120a to cover the sensing element 122a, the patterned metal layer 124a and the cross-shaped structure 126a. Here, the protective layer 130 exposes a portion of the patterned metal layer 124a, and the material of the protective layer 130 is, for example, silicon nitride (Si ₃ N ₄ ). Finally, please refer to FIG. 1F and FIG. 1G at the same time, from the second surface S2 of the substrate 110a to the first surface S1, a portion of the fourth oxide layer 70, a portion of the substrate 110a and the supporting structure 113a are removed to form an opening O connected to the stepped groove SC. In particular, the orthographic projection of the central portion 127a of the cross-shaped structure 126a on the substrate 110a overlaps with the opening O. At this point, the pressure sensing module 100a has been manufactured, and the substrate 110a has been formed into a cavity-semiconductor-on-insulator (C-SOI) substrate.

Please refer to FIG. 1G and FIG. 2D at the same time. In terms of structure, the pressure sensing module 100a includes a substrate 110a and a sensing layer 120a. The substrate 110a has a first surface S1 and a second surface S2 opposite to each other. The substrate 110a includes a step-shaped groove SC and an opening O. The step-shaped groove SC extends from the first surface S1 to the second surface S2, and the opening O extends from the second surface S2 to the first surface S1, and the step-shaped groove SC is connected to the opening O. Here, the step-shaped groove SC includes a first annular groove 111a and a second annular groove 115a. The first annular groove 111a is located between the opening O and the second annular groove 115a. Preferably, the diameter D1 of the first annular groove 111 a is smaller than the diameter D2 of the second annular groove 115 a and larger than the diameter D3 of the opening O.

The sensing layer 120a of this embodiment is disposed on the first surface S1 of the substrate 110a and covers the first surface S1 of the substrate 110a. The sensing layer 120a includes a sensing element 122a and a cross-shaped structure 126a. The cross-shaped structure 126a includes a central portion 127a and a plurality of extension portions 129a connected to the central portion 127a, wherein the central portion 127a and the extension portions 129a each include at least one hollow portion 125a. In particular, the orthographic projection of the central portion 127a of the cross-shaped structure 126a on the substrate 110a overlaps with the opening O of the substrate 110a. Here, the cross-shaped structure 126a may be in a double rib shape or a grid shape.

Furthermore, in this embodiment, the sensing layer 120a further includes an oxide layer 60 (i.e., a third oxide layer), an oxide layer 40 (i.e., a second oxide layer), an active layer 50, and a patterned metal layer 124a. The active layer 50 is located between the oxide layer 60 and the oxide layer 40. The oxide layer 40 is disposed on the first surface S1 of the substrate 110a. The sensing element 122a is buried in the active layer 50. The hollow portion 125a penetrates the oxide layer 60 and a portion of the active layer 50. The patterned metal layer 124a is disposed on at least one of the oxide layer 60 and the active layer 50.

In addition, the pressure sensing module 100a of this embodiment further includes a protection layer 130 disposed on the sensing layer 120a to cover the sensing element 122a and the cross-shaped structure 126a. Here, the material of the protection layer 130 is, for example, silicon nitride (Si ₃ N ₄ ).

Please refer to FIG3 , when pressure P1 is applied to the pressure sensing module 100a, the stepped groove SC can support the deformed sensing layer 120a to limit the deformation space of the sensing layer 120a. If the pressure P1 continues to increase, the deformation area of the sensing layer 120a will become smaller, and the maximum stress of the sensing layer 120a will decrease. Therefore, the maximum pressure that the sensing layer 120a can withstand will increase accordingly, that is, the withstand pressure (Burst Pressure) will increase.

In short, since the sensing layer 120a of the present embodiment has a cross-shaped structure 126a, and the central portion 127a and the extension portion 129a of the cross-shaped structure 126a each include a hollow portion 125a, the sensing layer 120a of the present embodiment can not only have better structural symmetry, but also reduce the rigidity of the sensing layer 120a through the hollow portion 125a to improve the sensing sensitivity. In addition, the substrate 110a of the present embodiment has a stepped groove SC design. When the sensing layer 120a is deformed by a pressure exceeding the operating range, the sensing layer 120a will reach the stepped groove SC below. If the pressure continues to increase, the deformation area of the sensing layer 120a will become smaller, and the withstand pressure (Burst Pressure) will increase. Therefore, the pressure sensing module 100a of the present embodiment has better sensing sensitivity and can improve the withstand pressure. In addition, since the sensing layer 120a of the present embodiment is not formed by back-side wet etching, but by grinding and dry etching or front-side wet etching technology, the thickness of the sensing layer 120a is easier to control and the process yield is high.

It should be noted that the following embodiments use the component numbers and some contents of the previous embodiments, wherein the same number is used to represent the same or similar components, and the description of the same technical contents is omitted. The description of the omitted parts can refer to the previous embodiments, and the following embodiments will not be repeated.

6A to 6D are cross-sectional schematic diagrams of partial steps of a method for manufacturing a pressure sensing module according to another embodiment of the present invention. FIG6E is a schematic top view of FIG6D. FIG7 is a schematic cross-sectional diagram of applying pressure to FIG6D. It should be noted that FIG6D is a schematic cross-sectional diagram along line V-V of FIG6E.

The manufacturing method of the pressure sensing module 100d of this embodiment is similar to the manufacturing method of the pressure sensing module 100a described above, and the difference between the two is that after the step of FIG. 1G, please refer to FIG. 6D first, and the cover plate 140 is bonded on the protective layer 130. In detail, first, please refer to FIG. 6A, and provide a cover plate 140, wherein the cover plate 140 has a third surface S3 and a fourth surface S4 opposite to each other. Then, deposit an oxide layer 15 on the third surface S3 of the cover plate 140, wherein the oxide layer 15 covers a portion of the third surface S3 of the cover plate 140. The oxide layer 15 is, for example, a silicon dioxide ( _SiO2 ) layer. Next, a photoresist layer 25 is formed on the third surface S3 of the cover plate 140, wherein the photoresist layer 25 covers the oxide layer 15 and a portion of the third surface S3 not covered by the oxide layer 15. At this time, the area on the third surface S3 not covered by the photoresist layer 25 is the area where the third groove 141 is to be formed, that is, the oxide layer 15 and the photoresist layer 25 cover the rest of the third surface S3, and a portion of the photoresist layer 25 is located on the oxide layer 15. Afterwards, the third surface S3 of the cover plate 140 not covered by the photoresist layer 25 is etched using the photoresist layer 25 as a mask to form the third groove 141. Here, a third groove 141 has been formed on the cover plate 140 , wherein the third groove 141 extends from the third surface S3 to the fourth surface S4 .

Next, referring to FIG. 6A and FIG. 6B , the photoresist layer 25 is removed to expose the oxide layer 15 and a portion of the third surface S3 of the cover plate 140 that is not covered by the oxide layer 15. At this time, the area on the third surface S3 that is not covered by the oxide layer 15 is the area where the fourth groove 143 is to be formed. Afterwards, a dry etching process is performed on the third surface S3 of the cover plate 140 to form the fourth groove 143 on the cover plate 140, wherein the fourth groove 143 extends from the third surface S3 to the fourth surface S4 and is connected to the third groove 141 to define the first portion 142.

Next, referring to FIG. 6C , the cover plate 140 is bonded to the protective layer 130 via the bonding material 150, wherein the third surface S3 of the cover plate 140 directly contacts the bonding material 150 and the protective layer 130. Here, the bonding material 150 is, for example, a dry film.

Afterwards, please refer to FIG. 6C, FIG. 6D and FIG. 6E simultaneously, a portion of the cover plate 140 is removed from the fourth surface S4 of the cover plate 140 toward the third surface S3, and a second portion 144 of the cover plate 140 is defined, wherein the second portion 144 surrounds the first portion 142. Here, the method of removing a portion of the cover plate 140 is, for example, grinding. Here, the cover plate 140 has been bonded to the protective layer 130, wherein the cover plate 140 includes a first portion 142 and a second portion 144 surrounding the first portion 142. The first portion 142 corresponds to at least a portion of the cross-shaped structure 126a, and the second portion 144 is bonded to the protective layer 130. More specifically, the first portion 142 corresponds to the central portion 127a of the cross-shaped structure 126a. At this point, the production of the pressure sensing module 100d has been completed. Here, the material of the cover plate 140 is the same as the material of the substrate 110 a , that is, the material of the cover plate 140 is cavity-semiconductor-on-insulator (C-SOI).

Please refer to FIG. 7 . When pressure P2 is applied to the pressure sensing module 100d, the deformed sensing layer 120a will first push against the upper cover plate 140. The cover plate 140 can limit the maximum deformation of the sensing layer 120a, thereby increasing the withstand pressure (Burst Pressure). In short, the pressure sensing module 100d of this embodiment can support the downwardly deformed sensing layer 120a through the design of the stepped groove SC of the substrate 110a, and can support the upwardly deformed sensing layer 120a through the provision of the cover plate 140.

In the simulation experiment, a pressure sensing module with a solid cross-shaped structure (i.e., without a hollow portion) in the prior art and the pressure sensing module 100a of the present embodiment with a double-rib or grid-shaped cross-shaped structure 126a/126b were used for comparison simulation.

Table 1 Pressure sensing module with solid cross structure in the prior art Pressure sensing module 100a having a double rib or grid-like cross structure 126a/126b Cavity size 1200 microns 1200 microns Rib size 60 microns to 80 microns 3 microns to 20 microns Number of ribs Single Plural Output sensitivity (mV/V/kPa) 100% 115% Film deformation stress (1ATM) 1420MPa 1410MPa Film deformation (1ATM) 35.8 microns 37.9 microns

As shown in Table 1 above, the sensitivity of the pressure sensing module 100a having a cross-shaped structure 126a/126b with double ribs or grids (i.e., having hollow portions 125a/125b) can be increased by 15%, and the deformation of the film is also increased, thereby increasing the withstand pressure (Burst Pressure).

In summary, the embodiments of the present invention have at least one of the following advantages or effects. In the design of the pressure sensing module of the present invention, the sensing layer includes a cross-shaped structure, and the central portion and the extension portion of the cross-shaped structure each include at least one hollow portion. Therefore, in addition to having better structural symmetry, the sensing layer of the present invention can also reduce the rigidity of the sensing layer through the hollow portion to improve the sensing sensitivity. In addition, the substrate of the present invention has a stepped groove design. When the sensing layer is deformed by a pressure exceeding the operating range, the sensing layer will top the stepped groove below. If the pressure continues to increase, the deformation area of the sensing layer will become smaller, and the pressure tolerance (Burst Pressure) will increase. Therefore, the pressure sensing module of the present invention has better sensing sensitivity and can improve the pressure tolerance.

However, the above is only the preferred embodiment of the present invention, and it cannot be used to limit the scope of the implementation of the present invention. That is, all simple equivalent changes and modifications made according to the scope of the patent application and the content of the invention description are still within the scope of the present invention. In addition, any embodiment or patent application of the present invention does not need to achieve all the purposes, advantages or features disclosed by the present invention. In addition, the abstract and title are only used to assist in searching for patent documents, and are not used to limit the scope of rights of the present invention. In addition, the terms "first", "second", etc. mentioned in this specification or patent application are only used to name the name of the element or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

10, 15: Oxide layer 20, 25: Photoresist layer 30: First oxide layer 40: Second oxide layer 50: Active layer 60: Third oxide layer 70: Fourth oxide layer 100a, 100d: Pressure sensing module 110a: Substrate 111a: First annular groove 113a, 113b, 113c, 113d: Support structure 115a: Second annular groove 120a, 120b: Sensing layer 122a: Sensing element 124a: Patterned metal layer 125a, 125b: Hollow part 126a, 126b: Cross-shaped structure 127a, 127b: Central part 129a, 129b: extension part 130: protective layer 140: cover plate 141: third groove 142: first part 143: fourth groove 144: second part 150: bonding material D1, D2, D3: diameter O: opening P1, P2: pressure S1: first surface S2: second surface S3: third surface S4: fourth surface SC: stepped groove T: depth W: wafer

Figures 1A to 1G are schematic cross-sectional views of a method for manufacturing a pressure sensing module according to an embodiment of the present invention. Figures 2A to 2C are schematic top views of Figure 1A. Figure 2D is a schematic top view of Figure 1F. Figure 3 is a schematic cross-sectional view of applying pressure to Figure 1G. Figure 4A is a schematic cross-sectional view of a partial step of a method for manufacturing a pressure sensing module according to another embodiment of the present invention. Figure 4B is a schematic top view of Figure 4A. Figure 5A is a schematic cross-sectional view of a partial step of a method for manufacturing a pressure sensing module according to another embodiment of the present invention. Figure 5B is a schematic top view of Figure 5A. Figures 6A to 6D are schematic cross-sectional views of partial steps of a method for manufacturing a pressure sensing module according to another embodiment of the present invention. Figure 6E is a schematic top view of Figure 6D. Figure 7 is a schematic cross-sectional view of Figure 6D when pressure is applied.

40: Second oxide layer

50: Active layer

60: Third oxide layer

70: Fourth oxide layer

100a: Pressure sensing module

110a: Base material

111a: First annular groove

115a: Second annular groove

120a: Sensing layer

122a: Sensing element

124a: Patterned metal layer

125a: hollow part

126a: Cross-shaped structure

127a: Central part

130: Protective layer

D1, D2, D3: caliber

O: Open

S1: First surface

S2: Second surface

SC: Step groove

Claims (19)

A pressure sensing module comprises: a substrate having a first surface and a second surface opposite to each other, the substrate comprising a stepped groove and an opening, the stepped groove extending from the first surface to the second surface, the opening extending from the second surface to the first surface, and the stepped groove connecting the opening; and a sensing layer disposed on the first surface of the substrate and covering the first surface of the substrate, the sensing layer comprising: at least one sensing layer; Element; and a cross-shaped structure, including a central portion and a plurality of extensions connected to the central portion, wherein the central portion and the extensions respectively include at least one hollow portion, and on a reference plane parallel to the second surface of the substrate, the orthographic projection of the central portion of the cross-shaped structure on the reference plane overlaps with the orthographic projection of the opening of the substrate and the step-shaped groove on the reference plane, and the sensing layer is not provided with a mass block on one side facing the step-shaped groove. A pressure sensing module as described in claim 1, wherein the stepped groove includes a first annular groove and a second annular groove, the first annular groove is located between the opening and the second annular groove, and the diameter of the first annular groove is smaller than the diameter of the second annular groove and larger than the diameter of the opening. The pressure sensing module as described in claim 1 further includes: a protective layer disposed on the sensing layer to cover the at least one sensing element and the cross-shaped structure. A pressure sensing module as described in claim 3, wherein the material of the protective layer includes silicon nitride. A pressure sensing module as described in claim 1, wherein the substrate is a silicon substrate covered with a cavity insulator. A pressure sensing module as described in claim 1, wherein the cross-shaped structure is in the shape of double ribs or a grid. A pressure sensing module as described in claim 1, wherein the at least one sensing element includes at least one piezoresistive sensor. A pressure sensing module comprises: a substrate having a first surface and a second surface opposite to each other, and the substrate comprises a stepped groove and an opening, the stepped groove extends from the first surface to the second surface, the opening extends from the second surface to the first surface, and the stepped groove is connected to the opening; a sensing layer is arranged on the first surface of the substrate and covers the first surface of the substrate, the sensing layer comprises: at least one sensing element; and a cross-shaped structure, comprising a central portion and a plurality of cross-shaped structures connected to the central portion. A plurality of extensions of the central portion and the extensions respectively include at least one hollow portion, and the orthographic projection of the central portion of the cross-shaped structure on the substrate overlaps with the opening of the substrate; a protective layer, disposed on the sensing layer to cover the at least one sensing element and the cross-shaped structure; and a cover plate, disposed on the protective layer, wherein the cover plate includes a first portion and a second portion surrounding the first portion, the first portion corresponds to at least a portion of the cross-shaped structure, and the second portion is bonded to the protective layer. A pressure sensing module as described in claim 8, wherein the material of the cover plate is the same as the material of the substrate. A pressure sensing module comprises: a substrate having a first surface and a second surface opposite to each other, the substrate comprising a stepped groove and an opening, the stepped groove extending from the first surface to the second surface, the opening extending from the second surface to the first surface, and the stepped groove connecting the opening; and a sensing layer disposed on the first surface of the substrate and covering the first surface of the substrate, the sensing layer comprising: at least one sensing element; and a cross-shaped structure comprising a central portion and a plurality of extension portions connected to the central portion, wherein the central portion and the extension portions are The cross-shaped structure includes at least one hollow portion, and the orthographic projection of the central portion of the cross-shaped structure on the substrate overlaps with the opening of the substrate, wherein the sensing layer further includes a first oxide layer, a second oxide layer, an active layer and a patterned metal layer, the active layer is located between the first oxide layer and the second oxide layer, the second oxide layer is arranged on the first surface of the substrate, the at least one sensing element is buried in the active layer, the at least one hollow portion penetrates the first oxide layer and a portion of the active layer, and the patterned metal layer is arranged on at least one of the first oxide layer and the active layer. A method for manufacturing a pressure sensing module includes: forming a first annular groove on a substrate to define at least one supporting structure on the substrate, the substrate having a first surface and a second surface opposite to each other, the first annular groove extending from the first surface to the second surface and surrounding the at least one supporting structure; forming a second annular groove on the substrate, the second annular groove extending from the first surface to the second surface and connecting to the first annular groove, the second annular groove and the first annular groove defining a stepped groove; forming a sensing layer on the substrate On the substrate, the sensing layer covers the first surface of the substrate, the sensing layer includes at least one sensing element; a cross-shaped structure is formed on the sensing layer, wherein the cross-shaped structure includes a central portion and a plurality of extensions connected to the central portion, the central portion and the extensions respectively include at least one hollow portion; and a portion of the substrate and the at least one supporting structure are removed from the second surface of the substrate toward the first surface to form an opening connected to the stepped groove, wherein the orthographic projection of the central portion of the cross-shaped structure on the substrate overlaps with the opening. The method for manufacturing the pressure sensing module as described in claim 11 further includes: Forming a protective layer on the sensing layer to cover the at least one sensing element and the cross-shaped structure. The manufacturing method of the pressure sensing module as described in claim 12 further includes: bonding a cover plate to the protective layer, the cover plate includes a first portion and a second portion surrounding the first portion, the first portion corresponds to at least a portion of the cross-shaped structure, and the second portion is bonded to the protective layer. The manufacturing method of the pressure sensing module as described in claim 13 further includes: forming a third groove on the cover plate, the third groove extending from a third surface to a fourth surface; forming a fourth groove on the cover plate, the fourth groove extending from the third surface to the fourth surface and connecting the third groove to define the first portion; and after joining the second portion of the cover plate to the protective layer, removing a portion of the cover plate from the fourth surface of the cover plate toward the third surface. The manufacturing method of the pressure sensing module as described in claim 11, wherein the step of forming the first annular groove on the substrate comprises: depositing an oxide layer on the first surface of the substrate, the oxide layer covering a portion of the first surface of the substrate; forming a photoresist layer on the first surface of the substrate, the photoresist layer covering the oxide layer and a portion of the first surface not covered by the oxide layer; and using the photoresist layer as a mask, etching the first surface of the substrate not covered by the photoresist layer to form the first annular groove. The manufacturing method of the pressure sensing module as described in claim 15, wherein the step of forming the second annular groove on the substrate comprises: removing the photoresist layer to expose the oxide layer and the portion of the first surface of the substrate not covered by the oxide layer; and performing a dry etching process on the first surface of the substrate to form the second annular groove. The manufacturing method of the pressure sensing module as described in claim 11, wherein the step of forming the sensing layer on the substrate includes: bonding a wafer and configuring a first oxide layer and a second oxide layer on the substrate, wherein the first oxide layer and the second oxide layer are located on opposite sides of the wafer; removing the first oxide layer and a portion of the wafer to form an active layer; forming the at least one sensing element in the active layer; configuring a third oxide layer on the active layer and the at least one sensing element; forming a patterned metal layer on the third oxide layer; and forming the at least one hollow portion to penetrate the third oxide layer and a portion of the active layer to define the cross-shaped structure. The method for manufacturing a pressure sensing module as described in claim 11, wherein the method for forming the at least one hollow portion includes a dry etching method or a front wet etching method. The manufacturing method of the pressure sensing module as described in claim 11, wherein the shape of the at least one supporting structure includes at least one of a circular shape, a rectangular shape and a cross shape.

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