US20090020501A1

US20090020501A1 - Method of forming passage in substrate for mems module

Info

Publication number: US20090020501A1
Application number: US11/935,707
Authority: US
Inventors: Chiung-Yueh TIEN; Hsi-Chen Yang
Original assignee: Lingsen Precision Industries Ltd
Current assignee: Lingsen Precision Industries Ltd
Priority date: 2007-07-18
Filing date: 2007-11-06
Publication date: 2009-01-22
Also published as: TW200904740A; TWI331595B

Abstract

A method of forming a passage in a substrate for a MEMS module is disclosed to include the steps of respectively forming a first support layer and a second support layer in a first space and a second space, which are respectively formed in a bottom side and a top side of a substrate by etching, by injection molding to define a sacrifice portion between the first and second support layers, and removing the sacrifice portion from the substrate by etching to form a passage defined between the first support layer and the second support layer in the substrate with two ends in communication with ambient atmosphere.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to Micro-Electro-Mechanical System (hereinafter referred to as “MEMS”) modules and more specifically, to a method of forming a passage in a substrate for use in a MEMS module.
2. Description of the Related Art
In order to improve the performance of a MEMS module, the mechanical support strength and other environmental factors, such as interference of noises, must be taken into account during packaging of the MEMS module. Some MEMS devices have a particular structure. For example, a microphone receives an external signal from the bottom side. In this case, the substrate must provide a curved sensor passage in communication with the bottom side of the MEMS chip so that the MEMS chip can receive an external signal from the bottom side.
However, it is difficult to form a nonlinear sensor passage in a substrate directly. According to conventional methods, the formation of the nonlinear sensor passage is done by means of stacking multiple plate members together. A plate member for this purpose has at least 0.18 mm usually. Forming a nonlinear sensor passage requires at least two plate members, i.e., a stack substrate structure will have a height at least 0.36 mm, which occupies a lot of space. Further, a stack substrate structure that is made by means of stacking multiple plate members together may encounter a peeling problem between two plate members.
Therefore, it is desirable to provide a method of forming a passage in a substrate for a MEMS module that eliminates the aforesaid drawbacks.

SUMMARY OF THE INVENTION

The present invention has been accomplished in view of the above-noted circumstances. It is one objective of the present invention to provide a substrate passage formation method for forming a passage through a substrate for a MEMS (Micro-Electro-Mechanical System) module, which has the characteristic of lowering the height of the substrate for use in a low profile MEMS module.
To achieve this objective of the present invention, the method of forming a passage in a substrate for a MEMS module provided by the present application comprises the steps of respectively forming a first support layer and a second support layer in a first space and a second space, which are respectively formed in a bottom side and a top side of a substrate having a thickness smaller than 0.3 mm by etching, by injection molding to define a sacrifice portion between the first and second support layers, and removing the sacrifice portion from the substrate by etching to form a passage defined between the first support layer and the second support layer in the substrate with two ends in communication with ambient atmosphere.
In a first exemplary embodiment to be detailed described hereinafter, a first support layer is formed by injection molding in a first space in the bottom side of the substrate, and then a second space is formed in the top side of the substrate to define the sacrifice portion between the first support layer and the second space. The two ends of the passage include an inlet and an outlet disposed on a top surface of the substrate.
In a second exemplary embodiment to be detailed described hereinafter, a first support layer and a second support are orderly formed by injection molding in a first space and a second space, which are orderly formed by etching in the bottom side and the top side of the substrate, to define the sacrifice portion between the first support layer (first space) and the second support layer (second space). The two ends of the passage include an inlet and an outlet disposed on a top surface of the substrate.
In a third exemplary embodiment to be detailed described hereinafter, a first support layer and a second support are orderly formed by injection molding in a first space and a second space, which are orderly formed by etching in the bottom side and the top side of the substrate, to define the sacrifice portion between the first support layer (first space) and the second support layer (second space). The first space has a first portion at the bottom side of the substrate and a second portion vertically penetrating the substrate and communicating with the first portion. The second space has a first portion at the top side of the substrate and a second portion vertically penetrating the substrate and communicating with the first portion. The two ends of the passage include an inlet and an outlet disposed on a top surface and a bottom surface of the substrate respectively.
The invention employs etching and injection molding techniques to form a passage in a substrate. Therefore, the invention allows the use of one single piece substrate to substitute for a conventional stack substrate structure. The spirit of the invention is to form a predetermined path step by step by means of etching, and to form multiple support layers step by step by means of injection molding. When compared with the prior art design, the invention can lower the height of the substrate.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a schematic drawing of a step of a first embodiment of the present invention, showing a substrate prepared before processing;

FIG. 2 is a schematic drawing showing a first space formed in a bottom portion of the substrate;

FIG. 3 is a schematic drawing showing a first support layer formed in the first space of the substrate;

FIG. 4 is a schematic drawing showing a second space and a sacrifice portion formed in a top portion of the substrate;

FIG. 5 is a schematic drawing showing a second support layer formed in the substrate;

FIG. 6 is a schematic drawing showing formation of a part of a passage in the substrate;

FIG. 7 is a schematic drawing showing the structure of the passage in the substrate;

FIG. 8 is a schematic drawing showing an application example of the first exemplary embodiment of the present invention in a MEMS module;

FIG. 9 is a schematic drawing of a step of a second embodiment of the present invention, showing a substrate prepared before processing;

FIG. 10 is a schematic drawing showing a first space formed in the substrate;

FIG. 11 is a schematic drawing showing a second space formed and a sacrifice portion defined in the substrate;

FIG. 12 is a schematic drawing showing a first support layer formed in the first space of the substrate;

FIG. 13 is a schematic drawing showing a second support layer formed in the second space of the substrate;

FIG. 14 is a schematic drawing showing formation of a part of a passage in the substrate;

FIG. 15 is a schematic drawing showing the structure of the passage in the substrate according to the second embodiment of the present invention;

FIG. 16 is a schematic drawing of a step of a third embodiment of the present invention, showing the structure of a substrate prepared before processing;

FIG. 17 is a schematic drawing showing a first space formed in the substrate;

FIG. 18 is a schematic drawing showing a second space and a sacrifice portion formed in the substrate:

FIG. 19 is a schematic drawing showing a first support layer formed in the first space of the substrate;

FIG. 20 is a schematic drawing showing a second support layer formed in the second space of the substrate;

FIG. 21 is a schematic drawing showing formation of a part of a passage in the substrate;

FIG. 22 is a schematic drawing showing the structure of the passage in the substrate according to the third embodiment of the present invention; and

FIG. 23 is a schematic drawing showing an application example of the third embodiment of the present invention in a MEMS module.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-7, a method of forming a passage in a substrate for MEMS module in accordance with a first embodiment of the present invention includes the flowing steps
a) Provide a substrate 10 having a thickness less than 0.30 mm or preferably 0.25 mm, as shown in FIG. 1. The substrate can be made from glass fiber-contained resin, epoxy, polyimide resin, FR4 resin, or BT (bismaleimide-triazine) resin. And then, etch the bottom side of the substrate 10 to form a first space 12 in the substrate 10, as shown in FIG. 2.
b) Fill up the first space 12 of the substrate 10 with a thermal setting resin by means of injection molding to form a first support layer 20 in the substrate 10, as shown in FIG. 3, having an anti-etching coefficient greater than the substrate 10.
c) Etch the top side of the substrate 10 to form a second space 14 so as to define a sacrifice portion 16 surrounded by the second spaces 14 and having a predetermined profile of the desired passage, as shown in FIG. 4.
d) Fill up the second space 14 with a thermal setting resin by means of injection molding to form a second support layer 22 having an anti-etching coefficient greater than the substrate 10, as shown in FIG. 5. In this embodiment, the a part of bottom of the second support layer 22 is integrally joined with a part of top of the first support layer 20; therefore, the first and second support layers 20, 22 can be treated as a single unit because it is difficult to recognize the boundary between the first support layer 20 and the second support layer 22.
e) Remove the sacrifice portion 16 from the substrate 10 by etching so as to form a passage 18 in the substrate 10, as shown in FIGS. 6 and 7. Because the first support layer 20 and the second support layer 22 have an anti-etching coefficient greater than the substrate 10, the first support layer 20 and the second support layer 22 can be kept intact when etching the substrate 10 to remove the sacrifice portion 16. After removal of the sacrifice portion 16, a passage 18 is formed in the substrate 10 in communication with the atmosphere, as shown in FIG. 7. The passage 18 has an inlet 181 and an outlet 182 respectively disposed on the surface of the substrate 10. According to this first embodiment, the inlet 181 and the outlet 182 are disposed at the top side of the substrate 10, and kept apart in horizontal direction.
According to the aforesaid procedure, this first embodiment employs etching and injection molding techniques to form a passage in a substrate. Therefore, the invention allows the use of one single piece substrate to substitute for a conventional stack substrate structure. The spirit of the invention is to form a predetermined path step by step by means of etching, and to form the said first support layer 20 and second support layer 22 step by step by means of injection molding so as to achieve formation of the desired passage in the substrate 10. When compared with the prior art design, the invention can reduce the height of the substrate 10 to 0.36 mm or smaller, thereby lowering the profile of the MEMS module.
FIG. 8 illustrates the application of a substrate 10 having the said passage 18 in a MEMS module 30. As illustrated, the MEMS module 30 comprises a substrate 10, a MEMS device 32, and a metal cap 34. The MEMS device 32 is installed in the top side of the substrate 10 and blocking the outlet 182. The metal cap 34 is capped on the top side of the substrate 10, defining with the top side of the substrate 10 an accommodation chamber 35 that accommodates the MEMS device 32. The metal cap 34 has a through hole 36 in air communication between the inlet 181 of the substrate 10 and the atmosphere. Thus, an external physical signal can go through the through hole 36 of the metal cap 34 to the MEMS device 32 via the passage 18, and therefore receiving of an external signal is achieved.
FIGS. 9-15 show the steps of a method of forming a passage in a substrate for MEMS module in accordance with a second embodiment of the present invention as follows.
a) Provide a substrate 40 having a thickness less than 0.30 mm or preferably 0.25 mm, as shown in FIG. 9. The substrate 40 can be made from glass fiber-contained resin, epoxy, polyimide resin, FR4 resin, or BT (bismaleimide-triazine) resin. Etch the bottom side of the substrate 40 to form a first space 42 in the substrate 40, as shown in FIG. 10.
b) Etch the top side of the substrate 40 to form a second space 44 and to define a sacrifice portion 46 surrounding the second space 44 and having a predetermined profile of the desired passage, as shown in FIG. 11.
c) Fill up the first space 42 of the substrate 40 with a thermal setting resin by means of injection molding to form a first support layer 50 in the substrate 40, as shown in FIG. 12, having an anti-etching coefficient greater than the substrate 40.
d) Fill up the second space 44 with a thermal setting resin by means of injection molding to form a second support layer 52 having an anti-etching coefficient greater than the substrate 40 as shown in FIG. 13.
e) Remove the sacrifice portion 46 from the substrate 40 by etching to form a passage 48 in the substrate 40, as shown in FIGS. 14 and 15.
Since the first support layer 50 and the second support layer 52 have an anti-etching coefficient greater than the substrate 40, the first support layer 50 and the second support layer 52 are kept intact when etching the substrate 40 to remove the sacrifice portion 46. After removal of the sacrifice portion 46, the first support layer 50 and the second support layer 52 define a passage 18 in the substrate 40 in communication with the atmosphere (see FIG. 15). The passage 48 has an inlet 481 and an outlet 482 respectively disposed on the surface of the substrate 40. According to this second embodiment, the inlet 481 and the outlet 482 are disposed at the top side of the substrate 40, and kept apart in horizontal direction. According to this second embodiment, the first space 42 and the second space 44 are formed in the substrate 40 by etching, and then the first support layer 50 and the second support layer 52 are formed in the substrate 40 by injection molding. The processing order of step b) and step c) according to this second embodiment is revered to the processing order of step b) and step c) of the aforesaid first embodiment. This second embodiment can also achieve formation of the desired passage in the substrate.
According to the aforesaid procedure, the second embodiment of the present invention employs etching and injection molding techniques to form a passage in a substrate. Therefore, the invention allows the use of one single piece substrate to substitute for a conventional stack substrate structure. The spirit of the invention is to make a predetermined path step by step by means of etching, and to form the said first support layer 50 and second support layer 52 step by step by means of injection molding so as to achieve formation of the desired passage in the substrate 40. When compared with the prior art design, the invention effectively reduces the height of the substrate, practical for the fabrication of a low profile MEMS module.
FIGS. 16-23 show the steps of a method of forming a passage in a substrate for MEMS module in accordance with a third embodiment of the present invention as follows.
a) Provide a substrate 60 having a thickness less than 0.30 mm or preferably 0.25 mm, as shown in FIG. 16. The substrate 60 can be made from glass fiber-contained resin, epoxy, polyimide resin, FR4 resin, or BT (bismaleimide-triazine) resin. And then, etch the substrate 60 to form a first space 62 having a first portion at the bottom side of the substrate 60 and a second portion vertically penetrating the substrate 60 and communicating with the first portion, as shown in FIG. 17.
b) Etch the substrate 60 to form a second space 64 having a first portion at the top side of the substrate 60 and a second portion vertically penetrating the substrate 60 and communicating with the first portion so as to define a sacrifice portion 66 of a predetermined pattern between the first and second spaces 62 and 64, as shown FIG. 18.
c) Fill up the first space 62 of the substrate 60 with a thermal setting resin by means of injection molding to form a first support layer 70 having an anti-etching coefficient greater than the substrate 60, as shown in FIG. 19.
d) Fill up the second spaces 64 with a thermal setting resin by means of injection molding to form a second support layer 72 having an anti-etching coefficient greater than the substrate 60, as shown in FIG. 20.
e) Remove the sacrifice portion 66 from the substrate 60 by etching to form a passage 68 in the substrate 60, as shown in FIGS. 22.
Since the first support layer 70 and the second support layer 72 have an anti-etching coefficient greater than the substrate 60, the first support layer 70 and the second support layer 72 can be kept intact when etching the substrate 60 to remove the sacrifice portion 66. After removal of the sacrifice portion 66, a passage 68 is formed in the substrate 60 in communication with the atmosphere, as shown in FIG. 22. The passage 68 has an inlet 681 and an outlet 682 respectively disposed at two opposite sides of the substrate 60. According to this third embodiment, the inlet 681 is disposed at the bottom side of the substrate 60, and the outlet 182 is disposed at the top side of the substrate 60, i.e., the inlet 181 and the outlet 182 are not overlapped in horizontal direction.
The processing procedure of this third embodiment is same as the aforesaid first embodiment. This third embodiment is to form a different shape of passage. Therefore, this third embodiment achieves the same effect as the aforesaid first embodiment.
FIG. 23 illustrates the application of a substrate 60 prepared according to the third embodiment of the present invention in a MEMS module 80. As illustrated, the MEMS module 80 comprises a substrate 60, a MEMS device 82, and a metal cap 84. The MEMS device 82 is installed in the top side of the substrate 60 and blocking the outlet 682. The metal cap 84 is capped on the top side of the substrate 60, defining with the top side of the substrate 60 an enclosed accommodation chamber 85 that accommodates the MEMS device 82. Thus, an external physical signal can go through the inlet 681 of the substrate 60 to the MEMS device 82 via the passage 68, and therefore receiving of an external signal is achieved.
As stated above, the invention employs etching and injection molding techniques to form a passage in a substrate. Therefore, the invention allows the use of one single piece substrate to substitute for a conventional stack substrate structure. The spirit of the invention is to make a predetermined passage step by step by means of etching, and to form multiple support layers step by step by means of injection molding. When compared with the prior art design, the invention can reduce the height of the substrate to 0.36 mm or smaller, thereby lowering the profile of the MEMS module.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A method of forming a passage in a substrate for a MEMS module, comprising the steps of:

a) etching a substrate having a thickness smaller than 0.30 mm to form a first space in a bottom side of the substrate;

b) forming a first support layer in first space of the substrate by means of injection molding;

c) etching the substrate to form a second space in a top side of the substrate to define a sacrifice portion between the second space and the first support layer;

d) forming a second support layer in the second space of the substrate by means of injection molding; and

e) removing the sacrifice portion from the substrate by etching to form a passage defined between the first support layer and the second support layer in the substrate with two ends in communication with ambient atmosphere.

2. The method as claimed in claim 1, wherein the substrate is made form a material selected form the group consisting of glass fiber-contained resin, epoxy, polyimide resin, FR4 resin, and bismaleimide-triazine resin.

3. The method as claimed in claim 1, wherein the first support layer is formed by a thermal setting resin having an anti-etching coefficient greater than the substrate.

4. The method as claimed in claim 1, wherein the second support layer is formed by a thermal setting resin having an anti-etching coefficient greater than the substrate.

5. A method of forming a passage in a substrate for a MEMS module, comprising the steps of:

b) etching the substrate to form a second space in a top side of the substrate to define a sacrifice portion between the first space and the second space;

c) forming a first support layer in the first space of the substrate by means of injection molding;

d) forming a second support layer in second space of the substrate by means of injection molding; and

6. The method as claimed in claim 5, wherein the substrate is made form a material selected form the group consisting of glass fiber-contained resin, epoxy, polyimide resin, FR4 resin, and bismaleimide-triazine resin.

7. The method as claimed in claim 5, wherein the first support layer is formed by a thermal setting resin having an anti-etching coefficient greater than the substrate.

8. The method as claimed in claim 5, wherein the second support layer is formed by a thermal setting resin having an anti-etching coefficient greater than the substrate.