MEMS sensor package and method for manufacturing the same.

Abstract

To provide a MEMS sensor package having excellent working efficiency at manufacturing and capable of obtaining high reliability.SOLUTION: A MEMS sensor package 1 comprises: a substrate 10; a ring-shaped dry film pattern 61 bonded to a front surface 11 of the substrate 10; and a MEMS sensor chip 20 including a detector S supported by a cylindrical support body 21 so as to be overlapped with a cavity part 24. The MEMS sensor chip 20 is fixed to the substrate 10 by allowing a ring-shaped mounting surface of the support body 21 to be bonded to the dry film pattern 61. Consequently, the MEMS sensor chip 20 is bonded to the substrate 10 by using the ring shaped dry film pattern 61, thereby to eliminate necessity to use a liquid joint material which makes it difficult to obtain high reliability and a die attachment material which makes it difficult to perform handling.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a MEMS sensor package and a method for manufacturing the same, and particularly to a MEMS sensor package having a structure in which a MEMS sensor chip is mounted on a substrate and a method for manufacturing the same.

Background Art

[0002] In recent years, MEMS sensor packages equipped with MEMS sensor chips such as microphones have been put into practical use. In a normal MEMS sensor package, a MEMS sensor chip is mounted on a substrate, and the MEMS sensor chip and the substrate are interconnected using bonding wires or the like. Here, in the example described in Patent Document 1, the MEMS sensor chip is fixed to the substrate by a bonding material. Further, in the example described in Patent Document 2, the MEMS sensor chip is fixed to the substrate by a die attach material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, unlike typical IC chips, MEMS sensor chips such as microphones have cavities on the back surface of the substrate, which is the mounting surface, leading to various problems in bonding to the substrate. For example, in bonding methods that involve curing a liquid adhesive, it is difficult to adjust the thickness of the adhesive to the designed level, and in some cases, the MEMS sensor chip may become tilted relative to the substrate. Also, if the amount of liquid adhesive is excessive, there is a risk that the adhesive may flow out and reach the bonding pads or land patterns on the surface of the substrate, or that the adhesive may flow into the through-holes provided in the substrate. For this reason, it has been difficult to obtain high reliability with bonding methods using liquid adhesives. On the other hand, in bonding methods that use die attach film (die attach material), it is necessary to pre-process the die attach film into an annular shape, and it is necessary to attach the die attach film, which is difficult to handle, to the precise position on the surface of the substrate, which greatly reduces work efficiency.

[0005] Therefore, the present invention aims to provide a MEMS sensor package and a method for manufacturing the same that offer excellent work efficiency during manufacturing and high reliability. [Means for solving the problem]

[0006] The MEMS sensor package according to the present invention comprises a substrate, an annular first dry film pattern bonded to one surface of the substrate, and a MEMS sensor chip including a cylindrical support and a detection unit supported by the support so as to overlap with a cavity in the support, wherein the MEMS sensor chip is fixed to the substrate by the annular mounting surface of the support being bonded to the first dry film pattern.

[0007] According to the present invention, since the MEMS sensor chip is bonded to the substrate using an annular dry film pattern, it is possible to fix the MEMS sensor chip to the substrate without using liquid bonding materials, which are difficult to obtain high reliability from, or die attach materials, which are difficult to handle.

[0008] In this invention, the substrate has through holes, and the first dry film pattern may be arranged to surround the through holes in a plan view. This makes it possible for a MEMS sensor chip to detect physical quantities such as sound waves entering through the through holes.

[0009] In the present invention, the elastic modulus of the first dry film pattern may be 10 MPa or more and 1 GPa or less. This makes it possible to prevent deformation of the detection part caused by the difference in thermal expansion coefficients between the substrate and the MEMS sensor chip.

[0010] The MEMS sensor package according to the present invention may further include a second dry film pattern bonded to one surface of a substrate and a controller IC mounted on the other surface of the substrate via the second dry film pattern. This makes it possible to mount the MEMS sensor chip and the controller IC on the surface of the substrate.

[0011] The method for manufacturing a MEMS sensor package according to the present invention is characterized by comprising: a first step of attaching a photosensitive dry film resist to one surface of a substrate; a second step of forming an annular first dry film pattern by exposing and developing the photosensitive dry film resist; a third step of preparing a MEMS sensor chip including a cylindrical support and a detection unit supported by the support so as to overlap the cavity of the support, and bonding the annular mounting surface of the support to the first dry film pattern; and a fourth step of curing the first dry film pattern.

[0012] According to the present invention, since the photosensitive dry film resist is patterned by photolithography, high work efficiency can be obtained, and the accuracy of the position and shape of the first dry film pattern can be improved.

[0013] In the second step, the second dry film pattern may be formed simultaneously with the first dry film pattern. This makes it possible to form the second dry film pattern without increasing the number of work steps. In this case, after the second step but before the fourth step, there may be an additional step of bonding the controller IC to the second dry film pattern. This makes it possible to mount the MEMS sensor chip and controller IC on the surface of the substrate. [Effects of the Invention]

[0014] Thus, according to the present invention, it is possible to provide a MEMS sensor package and a method for manufacturing the same that offer excellent work efficiency during manufacturing and high reliability. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating the structure of a MEMS sensor package 1 according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic plan view of the dry film patterns 61 and 62. [Figure 3] Figure 3 is a process diagram illustrating the manufacturing method of the MEMS sensor package 1. [Figure 4] Figure 4 is a process diagram illustrating the manufacturing method of the MEMS sensor package 1. [Figure 5] Figure 5 is a process diagram illustrating the manufacturing method of the MEMS sensor package 1. [Figure 6] Figure 6 is a process diagram illustrating the manufacturing method of the MEMS sensor package 1. [Figure 7] Figure 7 is a process diagram illustrating the manufacturing method of the MEMS sensor package 1. [Figure 8] Figure 8 is a process diagram illustrating the manufacturing method of the MEMS sensor package 1. [Figure 9]FIG. 9 is a process diagram for explaining a method of manufacturing the MEMS sensor package 1.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] FIG. 1 is a schematic cross-sectional view for explaining the structure of the MEMS sensor package 1 according to an embodiment of the present invention.

[0018] As shown in FIG. 1, the MEMS sensor package 1 according to this embodiment includes a substrate 10, a MEMS sensor chip 20 and a controller IC 30 mounted on the surface 11 of the substrate 10, and a metal cap 40 covering the MEMS sensor chip 20 and the controller IC 30.

[0019] The substrate 10 has a multilayer wiring structure and includes multiple insulating layers 101 to 105 and multiple conductor layers 110 to 115. The insulating layer 101 is a core layer and is made of a material such as FR4, which is a core material impregnated with resin. Conductor layers 110 and 111 are provided on the upper and lower surfaces of the insulating layer 101, respectively. The conductor layer 110 provided on the upper surface of the insulating layer 101 is covered with insulating layer 102. A conductor layer 112 is provided on the surface of the insulating layer 102. The conductor layer 112 is covered with insulating layer 103, and a conductor layer 113 is provided on the surface of insulating layer 103. On the other hand, the conductor layer 111 provided on the lower surface of the insulating layer 101 is covered with insulating layer 104. A conductor layer 114 is provided on the surface of insulating layer 104. The conductor layer 114 is covered with insulating layer 105, and a conductor layer 115 is provided on the surface of insulating layer 105. The insulating layers 102 to 105 can be made of a resin material with excellent processability and no core material. Here, the surface of the uppermost insulating layer 103 constitutes the surface 11 of the substrate 10, and the surface of the lowermost insulating layer 105 constitutes the surface 12 of the substrate 10. The conductive layer 113 provided on the surface 11 of the substrate 10 includes bonding pads connected to the controller IC 30. The conductive layer 114 provided on the surface 12 of the substrate 10 includes external terminals.

[0020] The MEMS sensor chip 20 has a support 21 made of silicon or the like, and a detection unit S supported by the support 21. The support 21 has a cylindrical structure that forms a cavity 24, and the detection unit S is supported by the support 21 so as to overlap with the cavity 24. In the example shown in Figure 1, the detection unit S includes a diaphragm 22 and a back plate 23, and is configured so that the diaphragm 22 can vibrate in response to sound waves. In this embodiment, a through hole 120 is provided in the substrate 10, and the MEMS sensor chip 20 is mounted so as to overlap the through hole 120 and the cavity 24. As a result, the diaphragm 22 vibrates in response to sound waves entering through the through hole 120, and this is converted into an electrical signal. In other words, in this embodiment, the MEMS sensor chip 20 constitutes a microphone. However, the MEMS sensor chip 20 is not limited to a microphone and may be other types of sensors.

[0021] The electrical signal generated by the MEMS sensor chip 20 is supplied to the controller IC 30 via bonding wire 51. The controller IC 30 is connected to a bonding pad provided on the surface 11 of the substrate 10 via bonding wire 52. Alternatively, a bonding pad directly connected to the MEMS sensor chip 20 may be provided on the surface 11 of the substrate 10.

[0022] The metal cap 40 is provided on the surface 11 of the substrate 10 so as to cover the MEMS sensor chip 20 and the controller IC 30. The metal cap 40 protects the MEMS sensor chip 20 and the controller IC 30, functions as an electromagnetic field shield, and also plays a role in improving the acoustic characteristics of the MEMS sensor chip 20. The metal cap 40 is fixed to the substrate 10 using a conductive adhesive 41, such as solder.

[0023] In contrast, dry film patterns 61 and 62 are used to fix the MEMS sensor chip 20 and controller IC 30 to the substrate 10, respectively. As shown in the schematic plan view Figure 2, the dry film pattern 61 has an annular structure surrounding the through hole 120 in plan view. The lower surface of the dry film pattern 61 is bonded to the surface 11 of the substrate 10, and the upper surface is bonded to the annular mounting surface of the support 21 of the MEMS sensor chip 20. The dry film pattern 62 is rectangular in plan view, with its lower surface bonded to the surface 11 of the substrate 10 and its upper surface bonded to the back surface of the controller IC 30. Both the dry film patterns 61 and 62 are films patterned by exposing and developing a photosensitive dry film resist, and they bond the substrate 10 to the MEMS sensor chip 20 and controller IC 30, as well as mitigating stress caused by the difference in thermal expansion coefficients between them.

[0024] To adequately relieve the stress caused by the difference in thermal expansion coefficients, it is preferable that the elastic modulus of the dry film patterns 61 and 62 be 10 MPa or more and 1 GPa or less. This is because if the elastic modulus of the dry film patterns 61 and 62 is greater than 1 GPa, the deformation of the dry film patterns 61 and 62 will be insufficient, and the stress will not be adequately relieved. On the other hand, if the elastic modulus of the dry film patterns 61 and 62 is less than 10 MPa, the fixing of the MEMS sensor chip 20 and controller IC 30 to the substrate 10 may be insufficient. To adequately relieve the stress caused by the difference in thermal expansion coefficients while ensuring high reliability, it is more preferable that the elastic modulus of the dry film patterns 61 and 62 be 500 GPa or less.

[0025] Furthermore, in order to more effectively relieve stress caused by differences in thermal expansion coefficients, it is preferable that the thickness of the dry film patterns 61 and 62 be 20 μm or more and 100 μm or less, and that the thickness uniformity be ±20% or less. Moreover, in order to ensure higher reliability, it is preferable that the dry film patterns 61 and 62 have an adhesive strength of 0.5 N or more and 3 N or more in an environment of 20 to 80°C.

[0026] Thus, in this embodiment, the MEMS sensor package 1 fixes the MEMS sensor chip 20 and controller IC 30 to the substrate 10 using dry film patterns 61 and 62, making it possible to horizontally fix the MEMS sensor chip 20 and controller IC 30 at the height position as designed.

[0027] Next, a method for manufacturing the MEMS sensor package 1 according to this embodiment will be described.

[0028] Figures 3 to 9 are process diagrams illustrating the manufacturing method of the MEMS sensor package 1 according to this embodiment.

[0029] First, as shown in Figure 3, a substrate 10 having a multilayer wiring structure is prepared, and through holes 120 are formed using methods such as drilling. Next, as shown in Figure 4, a photosensitive dry film resist 60 is attached to the surface 11 of the substrate 10. Preferably, the photosensitive dry film resist 60 is made of a material whose elastic modulus after curing is 10 MPa or more and 1 GPa or less. Then, as shown in Figure 5, after exposure through a mask 70, development is performed to form dry film patterns 61 and 62 as shown in Figure 6. At this stage, the dry film patterns 61 and 62 are uncured and have high adhesion. Also, since the dry film patterns 61 and 62 are formed by exposure and development, the accuracy of the position and shape of the dry film patterns 61 and 62 is much higher compared to the method of attaching a die attach material. In addition, since the dry film patterns 61 and 62 are formed simultaneously, the positional relationship between them can also be made as designed. There is no particular limit to the number of dry film patterns, and three or more dry film patterns may be formed. Even in this case, since the dry film pattern is formed by photolithography, the number of steps does not increase.

[0030] Next, as shown in Figure 7, a controller IC 30 is prepared and bonded to the dry film pattern 62 by placing the controller IC 30 on the dry film pattern 62. Then, as shown in Figure 8, a MEMS sensor chip 20 is prepared and bonded to the dry film pattern 61 by placing the MEMS sensor chip 20 on the dry film pattern 61. At this time, the MEMS sensor chip 20 is placed so that the annular mounting surface of the support 21 is in contact with the annular dry film pattern 61.

[0031] Next, after curing the dry film patterns 61 and 62 by heating, bonding wires 51 and 52 are formed as shown in Figure 9. When the dry film patterns 61 and 62 are cured by heating, stress is generated when they return to room temperature due to the difference in thermal expansion coefficients between the substrate 10 and the MEMS sensor chip 20 and controller IC 30. In particular, since the MEMS sensor chip 20 has a thin diaphragm 22, strong stress can cause the diaphragm 22 to deflect. However, in this embodiment, the elastic modulus of the dry film patterns 61 and 62 after curing is lower than that of general adhesive materials such as epoxy resin, preferably 10 MPa or more and 1 GPa or less, so the stress caused by the difference in thermal expansion coefficients is absorbed by the dry film patterns 61 and 62. This makes it possible to prevent deformation of the diaphragm 22.

[0032] Then, after bonding the metal cap 40 to the surface 11 of the substrate 10 using a conductive adhesive 41 such as solder, the substrate 10 is divided into individual pieces along the dicing line 80 shown by the dashed line, thereby completing the MEMS sensor package 1 according to this embodiment.

[0033] Thus, in this embodiment, since the dry film patterns 61 and 62 are formed by exposing and developing the photosensitive dry film resist 60, high positional accuracy can be obtained, and high work efficiency can be achieved because there is no need to use annular die attach materials that are difficult to handle. Moreover, as in the case where liquid bonding materials are used, there is no risk of excess bonding material reaching the bonding pads or land patterns on the surface 11 of the substrate 10, or flowing into the through holes 120 provided in the substrate 10. As a result, it is possible to manufacture a highly reliable MEMS sensor package 1 while ensuring high work efficiency.

[0034] Although preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention, and these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0035] 1 MEMS sensor package 10 circuit boards 11 One surface of the substrate 12 The other surface of the substrate 20 MEMS sensor chips 21 Support 22 Diaphragm 23 Backplate 24 Cavity 30 Controller World 40 Metal caps 41 Conductive adhesive 51, 52 Bonding wires 60 Photosensitive dry film resist 61, 62 Dry film patterns 70 masks 80 Dicing Lines 101-105 Insulating layer 110-115 Conductor layer 120 through holes S Detection Unit

Claims

1. circuit board and An annular first dry film pattern is bonded to one surface of the substrate, A MEMS sensor chip comprising a cylindrical support and a detection unit supported by the support so as to overlap with the cavity of the support, The MEMS sensor package is characterized in that the MEMS sensor chip is fixed to the substrate by bonding the annular mounting surface of the support to the first dry film pattern.

2. The MEMS sensor package according to claim 1, characterized in that the substrate has through holes, and the first dry film pattern is provided so as to surround the through holes in a plan view.

3. The MEMS sensor package according to claim 1, characterized in that the elastic modulus of the first dry film pattern is 10 MPa or more and 1 GPa or less.

4. A second dry film pattern is bonded to one of the surfaces of the substrate, The MEMS sensor package according to any one of claims 1 to 3, further comprising a controller IC mounted on one of the substrate surfaces via the second dry film pattern.

5. The first step involves attaching a photosensitive dry film resist to one surface of the substrate, A second step involves exposing and developing the photosensitive dry film resist to form an annular first dry film pattern, A third step involves preparing a MEMS sensor chip including a cylindrical support and a detection unit supported by the support so as to overlap the cavity of the support, and placing the MEMS sensor chip on the first dry film pattern so as to contact the first dry film pattern, and A method for manufacturing a MEMS sensor package, comprising a fourth step of curing the first dry film pattern.

6. The method for manufacturing a MEMS sensor package according to claim 5, characterized in that, in the second step, the second dry film pattern is formed simultaneously with the first dry film pattern.

7. The method for manufacturing a MEMS sensor package according to claim 6, further comprising the step of bonding a controller IC to the second dry film pattern after performing the second step and before performing the fourth step.

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