Packaging method and packaging structure suitable for vehicle-mounted high-reliability chip

Abstract

The invention discloses a packaging method suitable for a vehicle-mounted high-reliability chip, which not only retains the shading effect of black glue, but also avoids undercut, and solves the problem of reliability failure caused by poor surface uniformity. The method is characterized by comprising the following steps: combining a first photosensitive film on glass, and forming a cofferdam through a photoetching process; then, CIS wafer bonding, silicon through hole etching and RDL manufacturing are completed; and finally, a layer of second photosensitive film meeting the thickness requirement is attached to the surface of the silicon wafer to serve as a solder mask layer, and after the photoetching process, post-process TSV packaging is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor chip packaging, and in particular to a packaging method suitable for vehicle-mounted high-reliability chips. The present invention also provides a packaging structure obtained by the packaging method. Background Art

[0002] With the continuous progress of the semiconductor industry, application requirements are getting higher and higher, and the structure is becoming more and more complex. This has led to a series of technical problems. Among them, improving the reliability of automotive products is a very difficult problem. In the automotive image sensor chip industry, in order to improve the imaging quality of photosensitive chips and eliminate defects such as poor imaging and ghosting of photosensitive chips, the relatively new process method on the market is to use black photosensitive glue as a surface solder mask and a cofferdam on the glass to block stray light on the back and sides of the chip's photosensitive area. However, in the actual process, due to the characteristics of black photosensitive glue, the undercut at the bottom of the black glue is large after development, and there will be a risk of cofferdam & surface solder mask delamination during the reliability process.

[0003] The black glue currently used in the market has similar characteristics to traditional green glue, and is also coated on the surface of the product using a coating process. Although it solves the photosensitivity problem caused by stray light to a certain extent, it still has the same problem of uniformity across the entire surface as traditional green glue, and also introduces defects in the characteristics of the black glue itself. The black photosensitive glue used as a solder mask and cofferdam has a certain thickness. Due to poor light transmittance, the light cannot completely illuminate the bottom of the black glue. During the exposure process of the photolithography process, part of the bottom of the black glue is not fully illuminated, and the undercut of the bottom of the black glue is very large after development. In addition to the uneven thickness of the glue, cracking of the solder mask and the passivation layer may occur during reliability. In the reliability process, the risk of delamination of the cofferdam & surface solder mask is also very high. Therefore, improving this problem by exploring and researching new processes is a key factor in improving reliability. Summary of the invention

[0004] In view of the above problems, the present invention provides a packaging method suitable for vehicle-mounted high-reliability chips, which not only retains the shading effect of black glue, but also avoids undercut and solves the reliability failure caused by poor surface uniformity.

[0005] A packaging method suitable for automotive high-reliability chips, characterized by: combining a first photosensitive film on glass and forming a cofferdam through a photolithography process; then completing CIS wafer bonding, through silicon via etching and RDL production; finally, laminating a second photosensitive film that meets the thickness requirements on the surface of the silicon wafer as a solder mask, and completing the post-process TSV packaging after a photolithography process.

[0006] It is further characterized by:

[0007] It includes the following steps:

[0008] S1, attaching a first photosensitive film to the prepared optical glass, the first photosensitive film consisting of black photosensitive PI and transparent photosensitive adhesive;

[0009] S2, forming a cofferdam after a photolithography process, and coating a bonding adhesive on the surface of the cofferdam;

[0010] S3, bonding the CIS wafer to the structure coated with bonding adhesive, completing the thinning of the CIS wafer and etching of through silicon vias;

[0011] S4, preparing a dielectric layer on the exposed silicon surface of the CIS wafer and preparing the RDL;

[0012] S5, pre-cutting the grooves, and after half-cutting the grooves to the cofferdam of corresponding thickness, the whole surface of the semi-finished product is bonded with a second photosensitive film, which is composed of black photosensitive PI and transparent photosensitive adhesive;

[0013] S6, opening the surface pad and implanting the ball to form a solder ball by exposure and development;

[0014] S7, cutting along the groove to form the final product.

[0015] It is further characterized by:

[0016] The first photosensitive film in step S1 and the second photosensitive film in step S5 have the same material composition, but the thickness is arranged according to the requirements;

[0017] The first photosensitive film and the second photosensitive film are composed of a black photosensitive PI with a thickness of 0.5 to 3 um and a transparent photosensitive adhesive with a corresponding thickness;

[0018] In step S2, the bonding adhesive is applied by screen printing, 3D printing or rolling;

[0019] The material of the dielectric layer in step S4 is oxide or nitride of silicon, aluminum, zirconium, and titanium.

[0020] A packaging structure suitable for a vehicle-mounted high-reliability chip is obtained by packaging using a packaging method suitable for a vehicle-mounted high-reliability chip, and is characterized in that it includes a first photosensitive film and a second photosensitive film, wherein the first photosensitive film is used to form a cofferdam on the upper layer of glass, and the second photosensitive film is used as a solder resist layer.

[0021] It is further characterized in that: the first photosensitive film and the second photosensitive film have the same material composition, but the thickness is arranged according to the requirements;

[0022] The first photosensitive film and the second photosensitive film are composed of a black photosensitive PI with a thickness of 0.5 to 3 um and a transparent photosensitive adhesive with a corresponding thickness.

[0023] The beneficial effects of the present invention are:

[0024] (1) Solve the problem of poor light transmittance of traditional vinyl, insufficient light during exposure, and undercut at the bottom of the vinyl after development, thus improving reliability;

[0025] (2) Solve the problem of thick glue in the middle of the product and thin glue at the edge due to the coating process, which leads to cracking of the solder mask and passivation layer due to uneven stress during the reliability process;

[0026] (3) The glue thickness in the hole and the cutting path is uniform and thin, which reduces the stress caused by the glue thickness and improves reliability;

[0027] (4) The photosensitive film is solid after lamination, and there will be no problems such as product contamination caused by the transfer of liquid photosensitive adhesive after coating;

[0028] (5) Reduce the number of traditional photosensitive adhesive preparation processes, such as preparing the adhesive, vacuuming, and standing a few days in advance, saving manpower and time costs;

[0029] (6) The whole piece of photosensitive film is pasted efficiently, and the production capacity is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a process flow chart of the packaging method of the present invention;

[0031] Figure 2 It is a schematic diagram of the packaging structure of the present invention;

[0032] The names corresponding to the serial numbers in the figure are as follows:

[0033] Black photosensitive PI1, transparent photosensitive adhesive 2, cofferdam 3;

[0034] Glass 10 , first photosensitive film 20 , CIS wafer 30 , through silicon via 31 , RDL 40 , second photosensitive film 50 , bonding glue 60 , dielectric layer 70 , groove 80 , solder ball 90 , finished product 100 . DETAILED DESCRIPTION

[0035] A packaging method suitable for high-reliability automotive chips, comprising: combining a first photosensitive film 20 onto a glass 10, and forming a cofferdam 3 through a photolithography process; then, completing CIS wafer 30 bonding, through silicon via 31 etching, and RDL 40 production; finally, laminating a second photosensitive film 50 that meets the thickness requirements on the surface of the silicon wafer as a solder resist layer, and completing a post-process TSV packaging after a photolithography process.

[0036] It includes the following steps:

[0037] S1, attaching the first photosensitive film 20 to the prepared optical glass 10, the first photosensitive film 20 is composed of black photosensitive PI1 and transparent photosensitive adhesive 2;

[0038] S2, after the photolithography process, the cofferdam 3 is formed, and the bonding glue 60 is coated on the surface of the cofferdam 3, and the bonding glue 60 is coated by silk screen printing, 3D printing or rolling glue;

[0039] S3, the CIS wafer 30 is bonded to the overall structure coated with the bonding adhesive 60, and the thinning of the CIS wafer 30 and the etching of the through silicon via 31 are completed;

[0040] S4, preparing a dielectric layer 70 on the exposed silicon surface of the CIS wafer 30, and preparing the RDL 40, wherein the material of the dielectric layer 70 is an oxide or nitride including silicon, aluminum, zirconium, and titanium elements;

[0041] S5, pre-cutting the slot 80, after the slot 80 is half-cut to the cofferdam 3 of the corresponding thickness, the whole surface of the semi-finished product is attached to the second photosensitive film 50, the second photosensitive film 50 is composed of black photosensitive PI1 and transparent photosensitive adhesive 2;

[0042] S6, opening the surface pad and implanting the ball by exposure and development to form a solder ball 90;

[0043] S7, cutting along the slot to form a final product 100.

[0044] The first photosensitive film 20 in step S1 and the second photosensitive film 50 in step S5 are made of the same material, but the thickness is arranged according to the requirements; the first photosensitive film 20 and the second photosensitive film 50 are composed of a black photosensitive PI1 with a thickness of 0.5 to 3 um and a transparent photosensitive adhesive 2 with a corresponding thickness.

[0045] A packaging structure suitable for high-reliability chips on vehicles Figure 2 :It is obtained by packaging using a packaging method suitable for a high-reliability vehicle-mounted chip, and includes glass 10, a first photosensitive film 20, a bonding adhesive 60, a CIS wafer 30, a second photosensitive film 50, a dielectric layer 70, an RDL 40, and a ball implant 90;

[0046] The first photosensitive film 20 and the second photosensitive film 50 are made of the same material, but the thickness is arranged according to the requirements; the first photosensitive film 20 and the second photosensitive film 50 are composed of a black photosensitive PI1 with a thickness of 0.5 to 3 um and a transparent photosensitive adhesive 2 with a corresponding thickness;

[0047] The first photosensitive film 20 is compounded on the surface of the glass 10 through a transparent photosensitive adhesive 2, and a cofferdam 3 is formed after a photolithography process. The surface of the cofferdam 3 is coated with a bonding glue 60. The CIS wafer 30 is bonded to the overall structure coated with the bonding glue 60. The surface of the CIS wafer 30 is etched with a through silicon via 31. A dielectric layer 70 is provided on the exposed silicon surface of the CIS wafer 30. An RDL 40 is prepared on the surface of the dielectric layer 70. The second photosensitive film 50 covers the entire surface. The surface pads are opened and solder balls 90 are arranged by exposure and development.

[0048] Its beneficial effects are as follows:

[0049] (1) Solve the problem of poor light transmittance of traditional vinyl, insufficient light during exposure, and undercut at the bottom of the vinyl after development, thus improving reliability;

[0050] (2) Solve the problem of thick glue in the middle of the product and thin glue at the edge due to the coating process, which leads to cracking of the solder mask and passivation layer due to uneven stress during the reliability process;

[0051] (3) The glue thickness in the hole and the cutting path is uniform and thin, which reduces the stress caused by the glue thickness and improves reliability;

[0052] (4) The photosensitive film is solid after lamination, and there will be no problems such as product contamination caused by the transfer of liquid photosensitive adhesive after coating;

[0053] (5) Reduce the number of traditional photosensitive adhesive preparation processes, such as preparing the adhesive, vacuuming, and standing a few days in advance, saving manpower and time costs;

[0054] (6) The whole piece of photosensitive film is pasted efficiently, and the production capacity is greatly improved.

[0055] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0056] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A packaging method and packaging method suitable for a high-reliability chip mounted on a vehicle, characterized in that: The first photosensitive film is combined onto the glass and a cofferdam is formed through a photolithography process; Then, CIS wafer bonding, through silicon via etching and RDL production are completed; finally, a second photosensitive film that meets the thickness requirements is attached to the surface of the silicon wafer as a solder mask, and after the photolithography process, the post-process TSV packaging is completed.

2. A packaging method for a high-reliability chip suitable for use in a vehicle according to claim 1, characterized in that: It includes the following steps: S1, attaching a first photosensitive film to the prepared optical glass, the first photosensitive film consisting of black photosensitive PI and transparent photosensitive adhesive; S2, forming a cofferdam after a photolithography process, and coating a bonding adhesive on the surface of the cofferdam; S3, bonding the CIS wafer to the structure coated with bonding adhesive, completing the thinning of the CIS wafer and etching of through silicon vias; S4, preparing a dielectric layer on the exposed silicon surface of the CIS wafer and preparing the RDL; S5, pre-cutting the grooves, and after half-cutting the grooves to the cofferdam of corresponding thickness, the whole surface of the semi-finished product is bonded with a second photosensitive film, which is composed of black photosensitive PI and transparent photosensitive adhesive; S6, opening the surface pad and implanting the ball to form a solder ball by exposure and development; S7, cutting along the slot to form the final product.

3. The packaging method for a high-reliability chip suitable for use in a vehicle according to claim 2, characterized in that: The first photosensitive film in step S1 and the second photosensitive film in step S5 have the same material composition, but the thickness is arranged according to the requirements.

4. The packaging method for a high-reliability chip suitable for use in a vehicle according to claim 2, characterized in that: The first photosensitive film and the second photosensitive film are composed of a black photosensitive PI with a thickness of 0.5 to 3 um and a transparent photosensitive adhesive with a corresponding thickness.

5. The packaging method of a high-reliability chip suitable for vehicle use according to claim 2, characterized in that: In step S2, the bonding adhesive is applied by screen printing, 3D printing or adhesive rolling.

6. The packaging method of a high-reliability chip suitable for use in a vehicle according to claim 2, characterized in that: The material of the dielectric layer in step S4 is oxide or nitride of silicon, aluminum, zirconium, and titanium.

7. A packaging structure suitable for a vehicle-mounted high-reliability chip, which is obtained by packaging a packaging method suitable for a vehicle-mounted high-reliability chip according to any one of claims 1 to 6, characterized in that: The invention comprises a first photosensitive film and a second photosensitive film, wherein the first photosensitive film is used to form a cofferdam on the upper layer of the glass, and the second photosensitive film is used as a solder resist layer.

8. The packaging structure method for a high-reliability chip suitable for a vehicle according to claim 7, characterized in that The first photosensitive film and the second photosensitive film have the same material composition, but the thickness is arranged according to requirements.

9. The fan-out package packaging method with high heat dissipation performance according to claim 7, characterized in that: The first photosensitive film and the second photosensitive film are composed of a black photosensitive PI with a thickness of 0.5 to 3 um and a transparent photosensitive adhesive with a corresponding thickness.

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