Adhesive structure, packaging structure and manufacturing method thereof for low-stress MEMS packaging

Abstract

The present invention relates to the technical field of low-stress MEMS packaging, and particularly relates to an adhesive structure, a packaging structure and a manufacturing method thereof for low-stress MEMS packaging. The present invention relates to the technical field of low-stress MEMS packaging, and particularly relates to a three-dimensional packaging adhesive structure and a packaging structure for low-stress MEMS packaging of inertial sensors. The low-stress MEMS packaging structure includes a MEMS chip and a MEMS base, and the MEMS chip is pasted on the MEMS base through the adhesive structure for low-stress MEMS packaging as described in the first aspect of the present invention. The adhesive structure and the packaging structure for low-stress MEMS packaging have a good stress isolation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of low-stress MEMS packaging, and in particular to a three-dimensional bonding structure and a packaging structure for low-stress MEMS packaging of inertial sensors, as well as an integrated manufacturing method for realizing the bonding structure of low-stress MEMS packaging. Background technology MEMS inertial sensor devices are sensitive to the stress generated in the silicon chip during the packaging process, which is related to the chip warping when stress exists. In the chip bonding and packaging process, there are generally two methods: welding and organic glue bonding. Low-temperature and low-stress packaging is a common requirement for MEMS inertial sensor devices, and the method with the lowest process temperature is the organic glue bonding method. Commonly used adhesives include epoxy glue, silicone glue, etc. The traditional glue bonding method for chip attachment is either whole-layer gluing or local dot gluing. When the environmental temperature changes, residual stress is often generated due to the thermal mismatch of materials. The change of residual stress with the environmental temperature will be reflected in the output signal in the form of an electrical signal through the sensitive unit of the MEMS device, thus causing the output of the sensor to shift. The traditional glue bonding method has certain limitations, that is, good stress isolation effect and good chip-to-substrate adhesion cannot be obtained simultaneously. Summary of the Invention

[0002] In order to solve the deficiencies existing in the prior art, the present invention provides a bonding structure and a packaging structure for low-stress MEMS packaging, which have good stress isolation effect and good chip-to-substrate adhesion.

[0003] According to the technical solution provided by the present invention, as the first aspect of the present invention, there is provided a bonding structure for low-stress MEMS packaging, and the bonding structure for low-stress MEMS packaging includes: a stress isolation layer A and a stress isolation layer B alternately stacked from bottom to top; both the stress isolation layer A and the stress isolation layer B respectively include at least one stress isolation layer; the stress isolation layer includes a plurality of stress isolation strips arranged in an array.

[0004] Further, the stress isolation layer A includes a first stress isolation layer, and the stress isolation layer B includes a second stress isolation layer;

[0005] The stress isolation strips in the first stress isolation layer and the second stress isolation layer are respectively arranged side by side in a row, and the stress isolation strips in the first stress isolation layer intersect with the stress isolation strips in the second stress isolation layer.

[0006] Further, the stress isolation layer A includes a first stress isolation layer, and the stress isolation layer B includes a second stress isolation layer;

[0007] The stress isolation bars in the first stress isolation layer and the second stress isolation layer are respectively arranged side by side in a row, and the stress isolation bars in the first stress isolation layer are perpendicular to the stress isolation bars in the second stress isolation layer.

[0008] Further, the stress isolation layer A includes a first stress isolation layer and a second stress isolation layer with the same arrangement of stress isolation bars, and the stress isolation layer B includes a third stress isolation layer and a fourth stress isolation layer with the same arrangement of stress isolation bars; the stress isolation bars in the first stress isolation layer and the second stress isolation layer have the same arrangement; the stress isolation bars in the third stress isolation layer and the fourth stress isolation layer have the same arrangement.

[0009] And the stress isolation bars in the first stress isolation layer and the second stress isolation layer intersect with the stress isolation bars in the third stress isolation layer and the fourth stress isolation layer.

[0010] Further, the width of the stress isolation bar is 50 - 100 μm, and the spacing between the stress isolation bars is 100 - 500 μm. Further, the material used for the stress isolation bar is any one or more of: ceramics, thermosetting rubber, thermoplastic rubber, thermosetting resin, and thermoplastic resin.

[0011] Further, the thermal expansion coefficient of the stress isolation bar is 1×10 -6 ~~1×10 -3 [ / K].

[0012] As a second aspect of the present invention, there is provided a low-stress MEMS packaging structure, which includes a MEMS chip and a MEMS base, and the MEMS chip is adhered to the MEMS base through the adhesive structure for low-stress MEMS packaging as described in the first aspect of the present invention.

[0013] As a third aspect of the present invention, there is provided an integrated manufacturing method for an adhesive structure for realizing low-stress MEMS packaging. The adhesive structure is manufactured by an additive manufacturing method, and includes the following steps:

[0014] S1: Place the MEMS base on the printing platform;

[0015] S2: Manufacture the above-mentioned adhesive structure for low-stress MEMS packaging through the additive manufacturing technology of direct writing 3D printing;

[0016] S3: Adhere the MEMS chip to the adhesive structure to obtain the entire device;

[0017] S4: Heat the adhered entire device to cure the adhesive.

[0018] Further, in step S2: an adhesive structure is fabricated by an additive manufacturing technique of direct-write 3D printing, including:

[0019] S210: An additive manufacturing method of direct-write 3D printing is adopted to fabricate an adhesive structure on the bonding area of the MEMS base through an extrusion system;

[0020] Wherein, the material of the adhesive structure is silica gel; there are at least four isolation strips in the adhesive structure.

[0021] Further, in step S2: an adhesive structure is fabricated by an additive manufacturing technique of direct-write 3D printing, including:

[0022] S210: An additive manufacturing method of direct-write 3D printing is adopted to fabricate an adhesive structure on a silicon wafer through an extrusion system, and then the adhesive structure is cured at a high temperature;

[0023] S220: Apply an adhesive glue on the bonding area of the MEMS base;

[0024] S230: Paste the adhesive structure formed after high-temperature curing into the bonding area of the MEMS base to form a composite structure;

[0025] S240: Apply an adhesive glue on the upper surface of the adhesive structure;

[0026] Wherein, the material of the adhesive structure is a photocurable ceramic slurry; there are at least four isolation strips in the adhesive structure.

[0027] As can be seen from the above, the adhesive structure for low-stress MEMS packaging provided by the present invention has the following advantages compared with the prior art: During the packaging process, a three-dimensional adhesive structure is used to bond the MEMS housing and the chip together. This three-dimensional structure is fabricated by an additive manufacturing method (including but not limited to direct-write 3D printing), which has flexibility and controllability, and can simultaneously provide good chip-base adhesion and good stress isolation effect. The MEMS inertial sensor device produced by this manufacturing method has the advantages of small zero-temperature drift and reliable bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic longitudinal-sectional structure diagram of the first embodiment in the first aspect of the present invention.

[0029] Figure 2 It is a schematic longitudinal-sectional structure diagram of the second embodiment in the first aspect of the present invention.

[0030] Figure 3 It is a schematic longitudinal-sectional structure diagram of the third embodiment in the first aspect of the present invention.

[0031] Figure 4 (a)is a schematic three - dimensional structure diagram of the first embodiment in the first aspect of the present invention.

[0032] Figure 4 (b)is a schematic three - dimensional structure diagram of the second embodiment in the first aspect of the present invention.

[0033] Figure 4 (c)is a schematic three - dimensional structure diagram of the third embodiment in the first aspect of the present invention.

[0034] Figure 5 is a schematic structure diagram of the second aspect in the present invention.

[0035] Figure 6 is a schematic diagram of the stress distribution on the lower surface of the MEMS chip in the second aspect of the present invention, where Figure 6 (a)is a stress distribution diagram of the lower surface of the MEMS chip in the prior art, Figure 6 (b)is a stress distribution diagram of the lower surface of the MEMS chip when using the bonding structure described in the first embodiment of the first aspect of the present invention, Figure 6 (c)is a stress distribution diagram of the lower surface of the MEMS chip when using the bonding structure described in the second embodiment of the first aspect of the present invention, Figure 6 (d)is a stress distribution diagram of the lower surface of the MEMS chip when using the bonding structure described in the third embodiment of the first aspect of the present invention.

[0036] The darker the color, the greater the stress. It can be seen that the stress change on the lower surface of the MEMS chip under the existing structure is uneven, while the stress change on the lower surface of the MEMS chip using the three embodiments of the first aspect of the present invention is uniform and the stress is smaller, indicating that the silica gel foam structure has a good stress isolation effect.

[0037] Figure 7 is the stress distribution curve on the diagonal line of the upper surface of the MEMS chip when using the bonding structure described in the first aspect of the present invention; the stress distribution curve on the diagonal line of the upper surface of the MEMS chip under the existing structure fluctuates greatly and the stress changes greatly, while the stress distribution curve on the diagonal line of the upper surface of the MEMS chip using the three embodiments of the first aspect of the present invention fluctuates less, thus indicating that the stress change is small.

[0038] Figure 8 is a schematic flow diagram of the second embodiment in the third aspect of the present invention.

[0039] 100. Stress isolation layer A, 200. Stress isolation layer B, 300. Stress isolation strip, 410. First stress isolation layer, 420. Second stress isolation layer, 430. Third stress isolation layer, 440. Fourth stress isolation layer, 500. MEMS chip, 600. MEMS base. Detailed implementation manners

[0040] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. The same reference numerals are used for the same components. It should be noted that the terms "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings. The terms "inner" and "outer" respectively refer to the directions towards or away from the geometric center of a specific component.

[0041] As a first aspect of the present invention, a bonding structure for low-stress MEMS packaging is provided. The bonding structure for low-stress MEMS packaging includes the following three embodiments:

[0042] The first embodiment:

[0043] The bonding structure for low-stress MEMS packaging provided by the present invention includes: a plurality of stress isolation layers stacked in sequence, and each stress isolation layer includes a plurality of stress isolation bars 300. The plurality of stress isolation bars 300 are arranged at intervals in an array to form the stress isolation layer of this layer.

[0044] Preferably, the bonding structure includes a stress isolation A layer 100 and a stress isolation B layer 200 stacked alternately from bottom to top. The stress isolation A layer 100 includes a first stress isolation layer 410, and the stress isolation B layer 200 includes a second stress isolation layer 420. Both the first stress isolation layer 410 and the second stress isolation layer 420 respectively include a plurality of stress isolation bars 300 arranged side by side at intervals in a row, and the stress isolation bars 300 in the first stress isolation layer 410 are perpendicular to the stress isolation bars 300 in the second stress isolation layer 420.

[0045] The second embodiment:

[0046] The bonding structure for low-stress MEMS packaging provided by the present invention includes: a plurality of stress isolation layers stacked in sequence, and each stress isolation layer includes a plurality of stress isolation bars 300. The plurality of stress isolation bars 300 are arranged side by side at intervals to form the stress isolation layer of this layer.

[0047] Preferably, the bonding structure includes a stress isolation layer A 100 and a stress isolation layer B 200 which are alternately stacked from bottom to top. The stress isolation layer A 100 includes a first stress isolation layer 410 and a second stress isolation layer 420 with the stress isolation strips 300 arranged in the same pattern. The stress isolation layer B 200 includes a third stress isolation layer 430 and a fourth stress isolation layer 440 with the stress isolation strips 300 arranged in the same pattern. The stress isolation strips 300 in the first stress isolation layer 410 and the second stress isolation layer 420 cross the stress isolation strips 300 in the third stress isolation layer 430 and the fourth stress isolation layer 440. Preferably, the stress isolation strips 300 in the first stress isolation layer 410 and the second stress isolation layer 420 are perpendicular to the stress isolation strips 300 in the third stress isolation layer 430 and the fourth stress isolation layer 440.

[0048] The third embodiment:

[0049] The bonding structure for low-stress MEMS packaging provided by the present invention, the bonding structure for low-stress MEMS packaging includes: a plurality of stress isolation layers stacked in sequence, and each stress isolation layer includes a plurality of stress isolation strips 300. The plurality of stress isolation strips 300 are arranged at intervals in an array to form the stress isolation layer of this layer.

[0050] Preferably, the bonding structure includes a stress isolation layer A 100 and a stress isolation layer B 200 which are alternately stacked from bottom to top. The stress isolation layer A 100 includes a first stress isolation layer 410, and the stress isolation layer B 200 includes a second stress isolation layer 420. Each of the first stress isolation layer 410 and the second stress isolation layer 420 includes a plurality of stress isolation strips 300 arranged side by side at intervals in a row, and the stress isolation strips 300 in the first stress isolation layer 410 and the stress isolation strips 300 in the second stress isolation layer 420 cross each other to form a crossing angle.

[0051] As a second aspect of the present invention, there is provided a structure for low-stress MEMS packaging. The structure for low-stress MEMS packaging includes a MEMS chip 500 and a MEMS base 600. The MEMS chip 500 is adhered to the MEMS base 600 through the bonding structure for low-stress MEMS packaging according to any one of the embodiments in the first aspect of the present invention.

[0052] It can be understood that, because the bonding structure has a certain stress isolation effect, that is, when the temperature changes, the thermal expansion and contraction of the package and the glue have a relatively small impact on the chip, so the zero-point temperature drift of the MEMS can be reduced.

[0053] The manufacturing method of the structure for low-stress MEMS packaging provided by the third aspect of the present invention is as Figure 8As shown, it includes the following steps:

[0054] S1: Place the MEMS base 600 on the printing platform;

[0055] S2: Through the additive manufacturing technology of direct writing 3D printing, the bonding structure for low-stress MEMS packaging;

[0056] S3: Bond the MEMS chip 500 to the bonding structure to obtain the entire device;

[0057] S4: Heat the entire bonded device to cure the bonding adhesive.

[0058] It should be noted that in S2, in addition to using the additive manufacturing technology of direct writing 3D printing, other additive manufacturing technologies can also be used to manufacture the bonding structure described in the first aspect of the present invention.

[0059] For the first embodiment of the third aspect of the present invention:

[0060] The first step: Install the extrusion system of the 3D printer at the execution end of the multi-degree-of-freedom motion platform;

[0061] The second step: Load the material for preparing the bonding structure into the extrusion system; preferably, the material is a cured ceramic slurry;

[0062] The third step: By using the motion control technology and the extrusion system control to work together, an array structure of four or more stress isolation strips 300 can be extruded during the motion process, and the self-support is completed by using the high storage modulus characteristic of the material; preferably, set the extrusion air pressure of the extrusion system to 60 psi, and the needle head prints the ceramic three-dimensional bonding structure on the printer at a printing speed of 7 mm / s. The size of the bonding structure is 3.2 mm × 5 mm, 6 layers, the line width is about 100 μm, and the line spacing is 200 μm; The fourth step: After printing the bonding structure as described in any one of the embodiments of the first aspect of the present invention by the 3D printer, place it in a high-temperature environment to completely cure it. Preferably, put the ceramic three-dimensional bonding structure obtained in the second step into a muffle furnace, degrease it at 600 °C, and then put the degreased ceramic structure into a high-temperature muffle furnace and sinter it at 1500 °C for 2 hours;

[0063] The fifth step: Coat the bonding area of the MEMS base 600 with an adhesive; preferably, the adhesive is Dow Corning SE1700 silicone;

[0064] The sixth step: Paste the bonding structure formed after high-temperature curing in the fourth step to the bonding area of the MEMS base 600 to form a composite structure;

[0065] Step 7: Coat the upper surface of the bonding structure formed after high-temperature curing in Step 4 with an adhesive glue.

[0066] Step 8: Attach the MEMS chip 500 to the upper surface of the bonding structure.

[0067] Step 9: Place the complete structure obtained in Step 8 into an oven and heat it to cure the adhesive glue described in Step 5 and Step 7.

[0068] It should be noted that the width of the stress isolation strip 300 in the bonding structure is ~~100μm, and the number of layers of the stress isolation layer in the bonding structure is 4 or more.

[0069] For the second embodiment of the third aspect of the present invention:

[0070] Step 1: Install the extrusion system of the 3D printer at the execution end of the multi-degree-of-freedom motion platform.

[0071] Step 2: Load the material for preparing the bonding structure into the extrusion system; preferably, the material for preparing the bonding structure is Dow Corning SE1700 silicone, and the inner diameter of the extrusion system needle is 100μm.

[0072] Step 3: Place the MEMS base 600 on the printing platform of the printer. By using motion control technology and coordinating with the extrusion system control, an array structure of four or more stress isolation strips 300 can be extruded on the MEMS base 600 during the motion process, and self-support is completed by using the characteristics of high storage modulus of the material; preferably, set the air pressure of the extrusion system to 90psi and the needle moving speed to 1mm / s; among them, the air pressure of the extrusion system passes through a 7-fold supercharging device to extrude the silicone in the syringe from the needle and directly form it on the MEMS base 600.

[0073] Step 4: Attach the MEMS chip 500 to the upper surface of the bonding structure.

[0074] Step 5: Cure the structure obtained in Step 4 at high temperature; preferably, adopt the method of heating and curing at 80°C to cure and form the silicone three-dimensional bonding structure.

[0075] It can be understood that: during the encapsulation process, a three-dimensional bonding structure is used to bond the MEMS package and the chip together. This three-dimensional structure is manufactured by direct writing additive manufacturing, has flexibility and adjustable space, and can simultaneously provide good bonding strength and good stress isolation effect. The MEMS inertial sensor device produced by this manufacturing method has the advantage of small zero-temperature drift.

[0076] Those of ordinary skill in the art should understand that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit of the present invention shall be included within the protection scope of the present invention.

Claims

1. A bonding structure for low-stress MEMS packaging, characterized in that, The bonding structure for low-stress MEMS packaging includes: a stress isolation layer A (100) and a stress isolation layer B (200) stacked alternately from bottom to top; both the stress isolation layer A (100) and the stress isolation layer B (200) respectively include at least one layer of stress isolation layer; the stress isolation layer includes a plurality of stress isolation bars (300) arranged in an array. The stress isolation layer A (100) includes a first stress isolation layer (410) and a second stress isolation layer (420) with the same arrangement of stress isolation bars (300), and the stress isolation layer B (200) includes a third stress isolation layer (430) and a fourth stress isolation layer (440) with the same arrangement of stress isolation bars (300); the stress isolation bars (300) in the first stress isolation layer (410) and the second stress isolation layer (420) are arranged in the same way; the stress isolation bars (300) in the third stress isolation layer (430) and the fourth stress isolation layer (440) are arranged in the same way and the stress isolation bars (300) in the first stress isolation layer (410) and the second stress isolation layer (420) intersect with the stress isolation bars (300) in the third stress isolation layer (430) and the fourth stress isolation layer (440). The width of the stress isolation bar (300) is 50 - 150 μm, and the spacing between the stress isolation bars (300) is 100 - 500 μm. The coefficient of thermal expansion of the stress isolation strip (300) is 1×10 -6 ~~ 1×10 -3 [1 / K].

2. The bonding structure for low-stress MEMS packaging according to claim 1, characterized in that, The material used for the stress isolation bar (300) is any one or more of the following: ceramic, thermosetting rubber, thermoplastic rubber, thermosetting resin, and thermoplastic resin.

3. A low-stress MEMS packaging structure, characterized in that, The low-stress MEMS packaging structure includes a MEMS chip (500) and a MEMS base (600), and the MEMS chip (500) is adhered to the MEMS base (600) through the bonding structure for low-stress MEMS packaging described in any one of claims 1 - 2.

4. An integrated manufacturing method for a bonding structure for realizing low-stress MEMS packaging, characterized in that, The bonding structure is manufactured by additive manufacturing, including the following steps: S1: Place the MEMS base (600) on the printing platform; S2: Manufacture the bonding structure described in any one of claims 1 - 2 through the additive manufacturing technology of direct writing 3D printing; S3: Bond the MEMS chip (500) to the bonding structure to obtain the whole device; S4: Heat the bonded whole device to cure the adhesive.

5. The integrated manufacturing method for a bonding structure for realizing low-stress MEMS packaging according to claim 4, characterized in that, S2: Manufacture the bonding structure described in any one of claims 1 - 2 through the additive manufacturing technology of direct writing 3D printing, including: S210: Adopt the additive manufacturing method of direct writing 3D printing, and manufacture the bonding structure described in any one of claims 1 - 2 on the bonding area of the MEMS base (600) through an extrusion system; wherein, the material of the bonding structure is silicone; there are at least four layers of stress isolation bars (300) in the bonding structure.

6. The integrated manufacturing method for a bonding structure for realizing low-stress MEMS packaging according to claim 4, characterized in that, S2: Using the additive manufacturing technology of direct writing 3D printing to manufacture the bonding structure as described in any one of claims 1 to 2, including: S210: Adopting the additive manufacturing method of direct writing 3D printing, manufacturing the bonding structure as described in any one of claims 1 to 2 on a silicon wafer through an extrusion system, and then curing the bonding structure at a high temperature; S220: Coating an adhesive on the bonding area of the MEMS base (600); S230: Pasting the bonding structure formed after high-temperature curing into the bonding area of the MEMS base (600) to form a composite structure; S240: Coating the upper surface of the bonding structure with an adhesive; wherein, the material of the bonding structure is a photocurable ceramic slurry; and there are at least four stress isolation strips (300) in the bonding structure.

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