Optical via packaging process for MEMS devices

Abstract

The application discloses a wafer-level three-dimensional integrated MEMS device optical perforation packaging process based on OTEV technology, which has higher interconnection density, smaller pitch, smaller packaging size and thickness, better warping control, lower tool cost and natural integration advantage. The MEMS device product obtained by the process has high integration, the technology adopts a 3-in-1 wafer-level manufacturing method, and integrates the optical optical path part, the wire circuit and the packaging part of the product into one; the process can realize standardization and mass production, and has simple process steps and low cost; the whole MEMS device product obtained by the application has small size and low thickness; the whole MEMS device product is free of PCB and solder wire, so the structure is more compact and the performance is more stable; the several packaging materials used by the technology have consistent thermal expansion coefficients, the internal stress between the materials after packaging is low, and the product has high reliability and stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wafer level packaging technology of chips, in particular to a MEMS device optical perforation packaging process, which is suitable for terminal devices such as smart phones, wearable devices, tablet computers, notebook computers, and TVs. BACKGROUND

[0002] Packaging technology is the core link of the function embodiment and performance improvement of MEMS devices, and the complexity of MEMS devices leads to excessively high packaging cost, and the packaging cost accounts for more than 40% of the overall cost of the MEMS industry chain. With the rapid development of MEMS technology and market, the requirements for packaging technology are becoming higher and higher, mainly in integration, standardization, and small size. The ability of MEMS wafer level 3D packaging technology has become the key to the breakthrough of domestic MEMS industry.

[0003] MEMS (Micro Electro Mechanical System) refers to a system device with a feature size of microns or nanometers formed by micro-nano processing means such as semiconductor manufacturing guided by the theory of miniaturization and systematization. The three-dimensional mechanical structure of MEMS devices, product design and manufacturing technology diversity determine that MEMS packaging is different from and more complex than traditional IC packaging. From "low-cost packaging for consumer applications" to "high-reliability packaging for automotive and aviation industries that can withstand high temperature and harsh weather"; from "open packaging exposed to the atmosphere" to "sealed packaging that needs to be vacuumed" - various application requirements have brought many challenges to MEMS packaging. 5G communication, autonomous driving, artificial intelligence, Internet of Things, augmented reality (AR) / virtual reality (VR) and other technologies also bring new opportunities to the MEMS industry. For example, the 5G market is booming for RF MEMS represented by filters; environmental MEMS represented by gas sensors explore the potential of AIoT; optical MEMS represented by micro-mirrors open up business opportunities for automotive laser radar.

[0004] The main problems of existing optical MEMS packaging technology are:

[0005] 1) The integration is not high, and it is not easy to package the optical light (light path light guide), electricity (wire shadow line), and packaging structure together at one time.

[0006] 2) Because the existing MEMS packaging bottom substrate needs PCB support, the overall packaging module will be relatively thick.

[0007] 3) In the existing packaging technology, solder wire connection is required for conduction, and solder wire often causes product reliability problems due to problems such as disconnection and falling off. SUMMARY

[0008] In order to solve the above technical problems, the application designs a wafer-level three-dimensional integrated MEMS device optical perforation packaging process based on OTEV technology, which has higher interconnection density, smaller pitch, smaller packaging size and thickness, better warpage control, lower tool cost, and natural integration advantage.

[0009] The application adopts the following technical scheme:

[0010] A MEMS device optical perforation packaging process, the process steps are:

[0011] S1, chip reconstruction: using a full-automatic chip mounter to reconstruct the corresponding number of cut PD chips and Emitter chips to a glass carrier with double-sided tape according to the required pitch array;

[0012] S2, working mold A alignment and assembly: selecting a working mold A, aligning the working mold A with the chips and assembling a complete set, the glue injection groove A arranged in the working mold A covers the PD chips and Emitter chips, and the glue injection port A of the working mold A communicates with the glue injection groove A;

[0013] S3, glue injection and ultraviolet curing: using a full-automatic glue injection machine to inject black epoxy resin glue into the glue injection groove A cavity through the preset glue injection port A of the working mold A, and using the ultraviolet irradiation machine in the glue injection machine to irradiate the black epoxy resin glue to make the glue pre-cured, so that the black epoxy resin and the PD chips and Emitter chips form a wafer structure A;

[0014] S4, demolding after thermal curing: after putting the complete assembly in step S3 into a hot plate for baking, using an automatic demolding machine to separate the working mold A from the wafer structure A;

[0015] S5, glass carrier disassembly: disassembling the wafer structure A from the glass carrier with double-sided tape, at this time, the PD chips and Emitter chips have been wrapped by black epoxy resin glue and completely cured into a whole wafer structure A;

[0016] S6, laser drilling: using a full-automatic laser drilling machine to drill holes on the non-chip area of the wafer structure A according to the required position;

[0017] S7, patterned screen printing: using a screen printing device to screen print 20um thick glue on the upper surface of the wafer structure A according to the design size and heating curing, and forming a wiring channel on the upper surface of the wafer structure A through the screen printed pattern;

[0018] S8, conductive glue dispensing: using a full-automatic dispensing machine to dispense epoxy resin glue with conductive function on the screen printed layer, and then flowing the conductive glue into the wiring channel and through hole formed by screen printing through reflow soldering to form a wafer structure B;

[0019] S9. Wafer mounting: The entire wafer structure B is mounted onto the glass carrier using double-sided tape.

[0020] S10, Transparent Glue Spraying: Select working mold B. The working mold B has a recessed glue injection groove B that covers the entire wafer structure B. The glue injection port B of the working mold B is connected to the glue injection groove B. The glue injection groove B has protrusions corresponding to the PD chip and the Emitter chip respectively. The transparent epoxy resin is applied to the protrusions by spraying or pressing.

[0021] S11. Alignment and Imprinting: Align the working mold B, which has been coated with transparent epoxy resin liquid, with the wafer structure B and imprint them together. Use a UV curing machine to cure the transparent epoxy resin liquid.

[0022] S12. Injection and UV curing: Using a fully automatic injection machine, black epoxy resin is injected into the cavity of injection tank B through the injection port B preset by the working mold B. The black epoxy resin is then irradiated with a built-in UV irradiator to pre-cur the resin, so that the black epoxy resin forms wafer structure C with wafer structure B and transparent epoxy resin.

[0023] S13. Demolding after thermosetting: After baking the entire assembly on a hot plate, use an automatic demolding machine to separate the working mold B from the wafer structure C.

[0024] S14. Glass carrier removal: Remove wafer structure C from the glass carrier with double-sided tape. At this time, wafer structure B and transparent epoxy resin have been wrapped with black epoxy resin and completely cured into a whole wafer structure C.

[0025] S15, Silkscreen printing and ball placement: Silkscreen the conductive adhesive layer from the conductive adhesive interface on the back of the C-structure of the wafer, and place the balls by reflow soldering to form solder balls;

[0026] S16. Component cutting: The wafer structure C after silkscreen printing and ball placement is cut and separated using a fully automated wafer dicing machine to obtain MEMS device products.

[0027] Preferably, in step S2, the depth of the injection groove A recessed in the working mold A is matched with the height of the PD chip and the Emitter chip as required.

[0028] Preferably, the wiring channel in step S7 is connected to the through hole in step S6.

[0029] Preferably, in step S2, the injection port A of the working mold A is located at the center of the working mold A.

[0030] As preferred, in step S10, the glue injection port B of the working mold B is arranged at the center position of the working mold B.

[0031] As preferred, in step S16, the obtained MEMS device product comprises the shielding layer A and the shielding layer B formed by black epoxy resin, the light transmission layer formed by transparent epoxy resin, the conductive layer formed by conductive glue, the silk screen layer, the PD chip and the Emitter chip; the PD chip and the Emitter chip are arranged at intervals, the light transmission layer is arranged on the upper part of the PD chip and the Emitter chip respectively, the shielding layer A covers the outer edge of the PD chip, the shielding layer A covers the outer edge and the bottom surface of the Emitter chip, the shielding layer B covers the outer edge of the light transmission layer, the silk screen layer is arranged between the shielding layer A and the shielding layer B, the conductive layer is arranged in the wiring channel of the silk screen layer, and the conductive layer extends to the lower part of the shielding layer A through the through hole.

[0032] As preferred, the solder ball is arranged at the interface of the conductive layer below the shielding layer A.

[0033] As preferred, in step S10, the boss is in the shape of a circular truncated cone.

[0034] The present application has the following advantages: (1) the MEMS device product obtained by the process has high integration, the technology adopts the 3-in-1 wafer level manufacturing method, and integrates the optical light path part, the wire circuit and the packaging part of the product in one; (2) the process can realize standardization and mass production, and the process steps are simple and the cost is low; (3) the whole assembly has small size and low thickness; (4) the whole MEMS device product is free of PCB and solder wire, so the structure is more compact and the performance is more stable; (5) the thermal expansion coefficients of the several packaging materials used in the technology are consistent, the internal stress between the materials after packaging is low, and the product has high reliability and stability. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a structure schematic diagram in which the PD chip is uniformly distributed on the glass substrate in the present application;

[0036] Figure 2 is a structure schematic diagram in which the PD chip and the Emitter chip are uniformly distributed on the glass substrate in the present application;

[0037] Figure 3 is Figure 2 is a structure schematic diagram in which the working mold A is covered in the present application;

[0038] Figure 4 is Figure 3 is a structure schematic diagram in which the glue injection and solidification form the wafer structure A in the present application;

[0039] Figure 5 is Figure 4 is a structure schematic diagram after demolding in the present application;

[0040] Figure 6 is Figure 5 A structure diagram of a wafer structure A in the embodiment;

[0041] Figure 7 is Figure 6 A structure diagram after laser drilling in the embodiment;

[0042] Figure 8 is Figure 7 A structure diagram after forming a wiring channel by silk printing in the embodiment;

[0043] Figure 9 is Figure 8 A structure diagram of conductive glue flowing into the wiring channel and the through hole in the embodiment;

[0044] Figure 10 is Figure 9 A structure diagram of the wafer structure B being attached to the glass carrier by double-sided adhesive tape in the embodiment;

[0045] Figure 11 is A structure diagram of dispensing glue on the boss corresponding to the PD chip and the emitter chip in the working mold B in the embodiment;

[0046] Figure 12 Figure 10 is Figure 11 A structure diagram of the working mold B after dispensing glue in the embodiment;

[0047] Figure 13 is Figure 12 A structure diagram of injecting glue into the glue injection groove cavity of the working mold B in the embodiment;

[0048] Figure 14 is Figure 13 A structure diagram after demolding in the embodiment;

[0049] Figure 15 is Figure 14 A structure diagram of a wafer structure C in the embodiment;

[0050] Figure 16 is Figure 15 A structure diagram of silk printing conductive glue at the conductive glue interface on the back of the wafer structure C in the embodiment;

[0051] Figure 17 is Figure 16 A structure diagram of the silk printed conductive glue being planted with balls by reflow soldering in the embodiment;

[0052] Figure 18 is Figure 17 A structure diagram of the wafer structure element after cutting in the embodiment;

[0053] Figure 19 is a structural schematic diagram of a MEMS device product obtained by the MEMS device optical perforation packaging technology of the application;

[0054] In the figure: 1, glass carrier, 2, double-sided tape, 3, PD chip, 4, Emitter chip, 5, working mold A, 6, black epoxy resin glue, 7, glue injection port A, 8, wafer structure A, 9, through hole, 10, silk screen layer, 11, conductive glue, 12, wafer structure B, 13, working mold B, 14, glue injection port B, 15, boss, 16, wafer structure C, 17, conductive glue layer, 18, solder ball, 19, conductive layer, 20, shielding layer A, 21, shielding layer B, 22, light transmission layer. DETAILED DESCRIPTION

[0055] The technical solutions of the application will be further described below by specific embodiments and in combination with the drawings:

[0056] Embodiment: a MEMS device optical perforation packaging process, the process steps are:

[0057] S1, chip reconstruction: using a full-automatic chip mounter to array arrange and reconstruct a corresponding number of cut PD chips 3 and Emitter chips 4 according to the required spacing on a glass carrier 1 with double-sided tape 2, as shown in Figure 1 and Figure 2 ;

[0058] S2, working mold A alignment and assembly: selecting a working mold A 5, aligning the working mold A with the chips and assembling a complete set, the glue injection groove A provided in the working mold A covers the PD chips and the Emitter chips, and the glue injection port A of the working mold A communicates with the glue injection groove A, as shown in Figure 3 ;

[0059] S3, glue injection and ultraviolet curing: using a full-automatic glue injection machine to inject black epoxy resin glue 6 into the glue injection groove A cavity through the pre-set glue injection port A 7 of the working mold A, and using the ultraviolet irradiation machine in the glue injection machine to irradiate the black epoxy resin glue to make the glue pre-cured, so that the black epoxy resin and the PD chips and the Emitter chips form a wafer structure A 8, as shown in Figure 4 ;

[0060] S4, demolding after thermal curing: after placing the complete assembly in step S3 into a hot plate for baking, using an automatic demolding machine to separate the working mold A from the wafer structure A, as shown in Figure 5 ;

[0061] S5, glass carrier disassembly: the wafer structure A is disassembled from the glass carrier with double-sided tape, at this time each PD chip and Emitter chip has been wrapped with black epoxy resin glue and completely cured into a wafer structure A, as shown in Figure 6 ;

[0062] S6, laser drilling: using a full-automatic laser drilling machine to drill through holes 9 on the non-chip area of the wafer structure A according to the required position, as shown in Figure 7 ;

[0063] S7, patterned silk screen printing: using a silk screen printing device to silk screen 20um thick glue on the upper surface of the wafer structure A according to the design size and heat curing, forming a wiring channel on the upper surface of the wafer structure A through the silk screen pattern curing, as shown in Figure 8 ;

[0064] S8, conductive glue dispensing: using a full-automatic dispensing machine to point the epoxy resin glue with conductive function to the silk screen printed layer, and then through reflow soldering to make the conductive glue 11 flow into the entire silk screen printed wiring channel and through hole, forming a wafer structure B12, as shown in Figure 9 ;

[0065] S9, wafer mounting: mounting the whole wafer structure B on the glass carrier through double-sided tape, as shown in Figure 10 ;

[0066] S10, transparent glue spraying: selecting a working mold B13, the working mold B has an injection groove B for covering the whole wafer structure B, the injection groove B is provided with a boss 15 corresponding to the PD chip and the Emitter chip, and the injection groove B is provided with an injection port B14, and the transparent epoxy resin glue is dispensed on the boss through spraying or film pressing, as shown in Figure 11 ;

[0067] S11, alignment and impression: aligning and impressing the working mold B with the transparent epoxy resin glue dispensed on the boss with the wafer structure B, and using a ultraviolet curing machine to cure the transparent epoxy resin glue, as shown in Figure 12 ;

[0068] S12, glue injection and ultraviolet curing: using a full-automatic glue injection machine to inject black epoxy resin glue into the cavity of the injection groove B through the preset injection port B of the working mold B, and using the ultraviolet irradiation machine in the glue injection machine to irradiate the black epoxy resin glue to make the glue pre-cured, so that the black epoxy resin forms a wafer structure C16 with the wafer structure B and the transparent epoxy resin, as shown in Figure 13 ;

[0069] S13, demolding after thermal curing: after the entire assembly is placed in a hot plate for baking, an automatic demolding machine is used to separate the working mold B from the wafer structure C, as shown in Figure 14 ;

[0070] S14, disassembly of the glass carrier: the wafer structure C is disassembled from the glass carrier with double-sided tape, at this time the wafer structure B and the transparent epoxy resin have been wrapped by the black epoxy resin glue liquid and completely cured into a wafer structure C, as shown in Figure 15 ;

[0071] S15, screen printing and ball planting: screen printing of the conductive adhesive layer 17 is performed from the conductive adhesive interface at the back of the wafer structure C, and ball planting is performed by reflow soldering to form the soldering ball 18, as shown in Figure 16 and Figure 17 ;

[0072] S16, element cutting: the wafer structure C after screen printing and ball planting is cut and separated using a full-automatic wafer cutting machine to obtain the MEMS device product, as shown in Figure 18 .

[0073] In step S2, the depth of the glue injection groove A provided in the concave working mold A is matched with the height of the PD chip and the Emitter chip according to requirements.

[0074] The wiring channel in step S7 is in communication with the through hole in step S6.

[0075] In step S2, the glue injection port A of the working mold A is provided at the center position of the working mold A.

[0076] In step S10, the glue injection port B of the working mold B is provided at the center position of the working mold B.

[0077] In step S16, as shown in Figure 19 , the obtained MEMS device product includes the shielding layer A 20 and the shielding layer B 21 formed by the black epoxy resin, the light transmission layer 22 formed by the transparent epoxy resin, the conductive layer 19 formed by the conductive adhesive, the screen printing layer, the PD chip and the Emitter chip; the PD chip and the Emitter chip are provided in a spaced manner, the light transmission layer is provided on the upper part of the PD chip and the Emitter chip respectively, the shielding layer A covers the outer edge of the PD chip, the shielding layer A covers the outer edge and the bottom surface of the Emitter chip, the shielding layer B covers the outer edge of the light transmission layer, the screen printing layer 10 is provided between the shielding layer A and the shielding layer B, the conductive layer is provided in the wiring channel of the screen printing layer, and the conductive layer extends to below the shielding layer A through the through hole. The soldering ball is provided at the interface of the conductive layer below the shielding layer A.

[0078] In step S10, the boss is in the shape of a circular truncated cone.

[0079] The above-described embodiments are only the preferred ones of the present application, and do not limit the present application in any form, and other variants and modifications can be made without departing from the technical solutions recited in the claims.

Claims

1. A through-hole packaging process for MEMS devices, characterized in that, The process steps are as follows: S1. Chip Reconstruction: Using a fully automated chip mounter, the corresponding number of PD chips and Emitter chips are arranged in an array according to the required spacing and reconstructed onto a glass carrier with double-sided tape. S2. Alignment and assembly of working mold A: Select working mold A, align working mold A with the chip and assemble them into a set. The injection groove A set in the inner part of working mold A covers each PD chip and Emitter chip. The injection port A of working mold A is connected to the injection groove A. S3. Injection and UV curing: Using a fully automatic injection machine, black epoxy resin is injected into the injection tank A cavity through the injection port A preset in the working mold A. The black epoxy resin is then irradiated with the built-in UV irradiator in the injection machine to pre-cur the resin, so that the black epoxy resin forms a wafer structure A with each PD chip and Emitter chip. S4. Demolding after thermosetting: After baking the entire assembly in step S3 on a hot plate, use an automatic demolding machine to separate the working mold A from the wafer structure A. S5. Glass carrier removal: Remove wafer structure A from the glass carrier with double-sided tape. At this time, each PD chip and Emitter chip has been wrapped with black epoxy resin and completely cured into a whole wafer structure A. S6. Laser drilling: Using a fully automatic laser drilling machine, holes are drilled in the non-chip areas of wafer structure A at the required locations. S7. Patterned screen printing: Using screen printing equipment, a 20um thick adhesive liquid is screen printed on the upper surface of wafer structure A according to the design dimensions and then heated to cure. The screen-printed pattern is cured on the upper surface of wafer structure A to form wiring channels. S8. Conductive adhesive dispensing: Using a fully automatic dispensing machine, conductive epoxy resin is dispensed onto the screen-printed layer. Then, through reflow soldering, the conductive adhesive flows into the wiring channels and vias formed by the screen printing to form wafer structure B. S9. Wafer mounting: The entire wafer structure B is mounted onto the glass carrier using double-sided tape. S10, Transparent Glue Spraying: Select working mold B. The working mold B has a recessed glue injection groove B that covers the entire wafer structure B. The glue injection port B of the working mold B is connected to the glue injection groove B. The glue injection groove B has protrusions corresponding to the PD chip and the Emitter chip respectively. The transparent epoxy resin is applied to the protrusions by spraying or pressing. S11. Alignment and Imprinting: Align the working mold B, which has been coated with transparent epoxy resin liquid, with the wafer structure B and imprint them together. Use a UV curing machine to cure the transparent epoxy resin liquid. S12. Injection and UV curing: Using a fully automatic injection machine, black epoxy resin is injected into the cavity of injection tank B through the injection port B preset by the working mold B. The black epoxy resin is then irradiated with a built-in UV irradiator to pre-cur the resin, so that the black epoxy resin forms wafer structure C with wafer structure B and transparent epoxy resin. S13. Demolding after thermosetting: After baking the entire assembly on a hot plate, use an automatic demolding machine to separate the working mold B from the wafer structure C. S14. Glass carrier removal: Remove wafer structure C from the glass carrier with double-sided tape. At this time, wafer structure B and transparent epoxy resin have been wrapped with black epoxy resin and completely cured into a whole wafer structure C. S15, Silkscreen printing and ball placement: Silkscreen the conductive adhesive layer from the conductive adhesive interface on the back of the C-structure of the wafer, and place the balls by reflow soldering to form solder balls; S16. Component cutting: The wafer structure C after silkscreen printing and ball placement is cut and separated using a fully automated wafer dicing machine to obtain MEMS device products.

2. The MEMS device optical through-hole packaging process according to claim 1, characterized in that, In step S2, the depth of the injection groove A recessed in the working mold A is matched with the height of the PD chip and the Emitter chip as required.

3. The MEMS device optical through-hole packaging process according to claim 1, characterized in that, The wiring channel in step S7 is connected to the through hole in step S6.

4. The MEMS device optical through-hole packaging process according to claim 1, characterized in that, In step S2, the injection port A of the working mold A is located at the center of the working mold A.

5. The MEMS device optical through-hole packaging process according to claim 1, characterized in that, In step S10, the injection port B of the working mold B is located at the center of the working mold B.

6. The MEMS device optical through-hole packaging process according to claim 1, characterized in that, In step S16, the obtained MEMS device product includes a shielding layer A and a shielding layer B formed of black epoxy resin, a light-transmitting layer formed of transparent epoxy resin, a conductive layer formed of conductive adhesive, a silkscreen layer, a PD chip, and an Emitter chip. The PD chip and the Emitter chip are spaced apart, and the upper parts of the PD chip and the Emitter chip are respectively provided with light-transmitting layers. Shielding layer A covers the outer edge of the PD chip and the outer edge and bottom surface of the Emitter chip. Shielding layer B covers the outer edge of the light-transmitting layer. A silkscreen layer is provided between shielding layer A and shielding layer B. A conductive layer is provided in the wiring channels of the silkscreen layer, and the conductive layer extends to the bottom of shielding layer A through through-holes.

7. The MEMS device optical through-hole packaging process according to claim 6, characterized in that, Solder balls are provided at the interface of the conductive layer below the shielding layer A.

8. The MEMS device optical through-hole packaging process according to claim 1, characterized in that, In step S10, the boss is frustum-shaped.

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