Die bonding structure and its manufacturing method

Abstract

The present invention discloses a die bonding structure and a manufacturing method thereof, including: a substrate, a wafer located on the first surface of the substrate, a first layer of glue on the back surface of the wafer, and a second layer of glue covering at least the sidewalls of the wafer. Among them, the wafer is adhered to the first surface of the substrate at least through the first layer of glue. The die bonding structure provided by the present invention enables the junction temperature generated by the wafer during operation to be conducted to the substrate through the first layer of glue under the wafer, and at the same time can be conducted to the substrate through the second layer of glue on the sidewalls of the wafer. Moreover, there are no voids in the first layer of glue, which can improve the heat dissipation ability of the package while ensuring stable insulation ability.

Description

Technical Field

[0001] The present invention relates to the technical field of chip packaging, and in particular, to a die bonding structure and a manufacturing method thereof. Background Art

[0002] With the rapid increase in packaging integration, more than two silicon chips will be integrated in the same package. At the same time, due to different wafer process requirements, the substrate voltages of different chips in the same package will be different, and some chips need to be insulated and isolated.

[0003] Currently, the processes for using non-conductive die attach adhesives for isolation include brushing glue, pasting DAF (Die Attach Film) film, and dispensing glue:

[0004] 1) The brushing glue process and the DAF film pasting process can well control the thickness of the glue layer and are not prone to generating voids. The insulation reliability is significantly better than the dispensing glue process. However, the thermal conductivity of these two materials is very low (<1W / mK), which is not conducive to the overall heat dissipation design of the package.

[0005] 2) The dispensing glue process can use non-conductive glue with a high thermal conductivity (>2W / mK) to improve the heat dissipation design. However, the dispensing glue process is not easy to control the glue thickness and is prone to generating voids, which affects the insulation ability of the glue layer. Especially when used in high-voltage products (>100V), there is a potential risk of high-voltage breakdown failure.

[0006] In summary, the current design does not well meet the requirements of both isolation and heat dissipation. Summary of the Invention

[0007] In view of this, the present invention provides a die bonding structure and a manufacturing method thereof, which can improve the heat dissipation ability of the package while ensuring a stable insulation and isolation ability.

[0008] According to a first aspect of the present invention, a die bonding structure is provided, including: a substrate, a wafer located on a first surface of the substrate, a first layer of glue located on the back surface of the wafer, and a second layer of glue covering at least the sidewalls of the wafer, wherein the wafer is pasted on the first surface of the substrate at least through the first layer of glue.

[0009] Preferably, the first layer of glue and the second layer of glue are formed by different processes.

[0010] Preferably, the first layer of glue and the second layer of glue are different.

[0011] Preferably, the second layer of glue is further located on the first surface of the substrate, and the wafer is pasted on the first surface of the substrate through the first layer of glue and the second layer of glue.

[0012] Preferably, the first surface of the substrate is set to be flat.

[0013] Preferably, the first surface of the substrate includes a groove, and the wafer is mounted in the groove.

[0014] Preferably, the upper surface of the wafer is higher than the top of the groove, wherein the upper surface of the wafer is opposite to the back surface of the wafer.

[0015] Preferably, the groove has a shape that is narrower at the bottom and wider at the top.

[0016] Preferably, the first layer of glue is formed by a glue brushing process.

[0017] Preferably, the first layer of glue is formed by attaching a DAF film to the back surface of the wafer.

[0018] Preferably, the second layer of glue is formed by a dispensing process.

[0019] Preferably, the groove is formed by etching or mechanical indentation.

[0020] Preferably, the height of the second layer of glue climbing on the side wall of the wafer is not greater than 90% of the thickness of the wafer, and the direction of the first layer of glue climbing on the side wall of the wafer is from the back surface of the wafer to the upper surface of the wafer, and the upper surface of the wafer is opposite to the back surface of the wafer.

[0021] Preferably, the first layer of glue and the second layer of glue are set as non-conductive glue.

[0022] Preferably, the second layer of glue has a high thermal conductivity.

[0023] Preferably, the thermal conductivity of the second layer of glue is not less than 2 W / mK.

[0024] Preferably, the first layer of glue does not include voids.

[0025] Preferably, the first layer of glue has a uniform thickness.

[0026] Preferably, the first surface of the substrate includes a pad, and the wafer is pasted on the pad.

[0027] According to a second aspect of the present invention, there is provided a method for manufacturing a die bonding structure, including:

[0028] Providing a wafer and a substrate;

[0029] Forming a first layer of glue on the back surface of the wafer;

[0030] Forming a second layer of glue covering at least the side wall of the wafer; and

[0031] Paste the wafer onto the first surface of the substrate at least through the first layer of glue.

[0032] Preferably, the process of forming the first layer of glue is different from the process of forming the second layer of glue.

[0033] Preferably, the second layer of glue is also formed on the first surface of the substrate, and the wafer is pasted onto the first surface of the substrate through the first layer of glue and the second layer of glue.

[0034] Preferably, on the sidewall of the wafer, the second layer of glue covering the sidewall of the wafer is formed by a dispensing process.

[0035] Preferably, the steps of forming the second layer of glue include:

[0036] Form the second layer of glue on the first surface of the substrate by a dispensing process;

[0037] When pasting the wafer onto the first surface of the substrate including the second layer of glue, apply a certain pressure so that part of the second layer of glue can creep onto the sidewall of the wafer.

[0038] Preferably, before pasting the wafer onto the first surface of the substrate, the second layer of glue is not cured.

[0039] Preferably, the first layer of glue is formed by a brushing process.

[0040] Preferably, the first layer of glue is formed by pasting a DAF film on the back surface of the wafer.

[0041] Preferably, the first surface of the substrate is set to be flat.

[0042] Preferably, the first surface of the substrate includes a groove, and the chip is installed in the groove.

[0043] Preferably, the groove is formed by etching or mechanical indentation.

[0044] Preferably, the height of the second layer of glue creeping on the sidewall of the wafer is not greater than 90% of the thickness of the wafer, the direction in which the first layer of glue creeps on the sidewall of the wafer is the direction extending from the back surface of the wafer to the upper surface of the wafer, and the upper surface of the wafer is opposite to the back surface of the wafer.

[0045] Preferably, the upper surface of the substrate includes pads, and the wafer is pasted on the pads.

[0046] According to the die bonding structure and its manufacturing method provided by the present invention, two layers of non-conductive adhesives are formed by different processes, enabling the junction temperature generated during the operation of the wafer to be conducted to the substrate through the first layer of adhesive under the wafer, and at the same time, to the substrate through the second layer of adhesive on the sidewall of the wafer, thereby enhancing the heat dissipation capacity of the package. In addition, the first layer of adhesive formed by the glue brushing process and the method of attaching the DAF film has a uniform thickness and is not prone to generating voids, which can play a good role in insulating and isolating the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a cross-sectional view of the die bonding structure according to the first embodiment of the present invention;

[0048] Figure 2 is a cross-sectional view of the die bonding structure according to the second embodiment of the present invention;

[0049] Figure 3 is a cross-sectional view of the die bonding structure according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the drawings, the same components are denoted by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. In addition, some well-known parts may not be shown. For the sake of brevity, the structure obtained after several steps may be described in one drawing. Many specific details of the present invention are described below, such as the structure, material, size, processing technology and techniques of each component, in order to understand the present invention more clearly. However, as those skilled in the art can understand, the present invention can be implemented without these specific details.

[0051] The present invention provides a die bonding structure, including: a substrate, a wafer located on the first surface of the substrate, a first layer of adhesive on the back surface of the wafer, and a second layer of adhesive covering at least the sidewall of the wafer, wherein the wafer is attached to the first surface of the substrate at least through the first layer of adhesive. The first layer of adhesive and the second layer of adhesive are formed by different processes.

[0052] As Figure 1As shown, it is a cross-sectional view of the die bonding structure according to the first embodiment of the present invention. The die bonding structure includes a substrate 101, a first layer of glue 103, a second layer of glue 102, and a wafer 104. Among them, the wafer 104 is located on the first surface of the substrate 101, the first layer of glue 103 is located on the back surface of the wafer 104, the second layer of glue 102 at least covers the side wall of the wafer 104, and the wafer 104 is pasted on the first surface of the substrate 101 at least through the first layer of glue 103. Specifically, in this embodiment, the first surface of the substrate is flat, and the second layer of glue 102 includes a first part located on the first surface of the substrate and a second part that climbs on the side wall of the wafer, that is, the wafer 104 is pasted on the first surface of the substrate through the first layer of glue 103 and the first part of the second layer of glue 102, and the second layer of glue 102 covers the back surface of the wafer (including the first layer of glue 103 on the back surface of the wafer) and part of the side wall of the wafer.

[0053] It should be noted that the second layer of glue cannot climb to the upper surface (active surface) of the wafer, and the upper surface of the wafer is opposite to the back surface. Further, the height of the second part of the second layer of glue climbing on the side wall of the wafer is not greater than 90% of the thickness of the wafer, and the direction in which the second layer of glue climbs on the side wall of the wafer is the direction extending from the back surface of the wafer to the upper surface of the wafer, and the upper surface of the wafer is opposite to the back surface of the wafer.

[0054] In this embodiment, both the first layer of glue and the second layer of glue are non-conductive glue, but the first layer of glue and the second layer of glue are different. Among them, the second layer of glue is formed by a dispensing process, and the second layer of glue has a high thermal conductivity. Specifically, the thermal conductivity of the second layer of glue is not less than 2 W / mK. The first layer of glue is formed by brushing glue or pasting a DAF film on the back surface of the wafer. Therefore, the first layer of glue has a uniform thickness and is not easy to generate voids. In addition, the first surface of the substrate also includes pads, that is, the wafer 104 is pasted on the pads on the first surface of the substrate.

[0055] The present invention also provides a manufacturing method of a die bonding structure, including: providing a wafer and a substrate; forming a first layer of glue on the back surface of the wafer; forming a second layer of glue that at least covers the side wall of the wafer; and pasting the wafer on the first surface of the substrate at least through the first layer of glue.

[0056] Specifically, the steps of the manufacturing method of the die bonding structure according to the first embodiment of the present invention are as follows:

[0057] Step 1: Form a first layer of glue 103 on the back surface of the wafer 104.

[0058] Specifically, the method for forming the first layer of glue 103 includes forming it by means of glue brushing process or pasting a DAF film on the back surface of the wafer. The first layer of glue formed by these two processes is relatively easy to control the thickness of the glue layer, making it have a uniform thickness and not easily generating voids, which can ensure the insulation isolation of the wafer. The first layer of glue is a non-conductive glue, such as 8006 glue.

[0059] Among them, the glue brushing process includes: uniformly attaching the glue to the back surface of the wafer by means of doctor blade coating or spin coating on the back surface of the wafer, and performing baking pre-curing to ensure the connection between the glue and the back surface of the wafer. Generally, the wafer is thinned to a specified thickness before forming the second layer of glue on the back surface of the wafer.

[0060] Step two: Form a second layer of glue 102 on the first surface of the substrate 101.

[0061] Specifically, the second layer of glue 102 is formed on the first surface of the substrate 101 by means of dispensing process. The dispensing process is to coat the glue material in the syringe or use other transfer methods to coat the glue at the specified position on the first surface of the substrate to form the second layer of glue 102, and no curing treatment is performed on the second layer of glue. Among them, the second layer of glue is a non-conductive glue, such as 8472 glue, 8488 glue, etc. The second layer of glue has a high thermal conductivity. Specifically, the thermal conductivity of the second layer of glue is not less than 2 W / mK. In this embodiment, the first surface of the substrate also includes pads, and the second layer of glue is located on the pads of the substrate.

[0062] It should be noted that the order of the above step one and step two is not limited. It is also possible to perform the process of step two first, then the process of step one, or the two steps can be performed simultaneously.

[0063] Step three: Paste the wafer 104 on the first surface of the substrate 101 with the back surface facing the first surface of the substrate 101. Among them, when pasting the wafer 104 on the first surface of the substrate 101, a certain pressure is applied so that part of the second layer of glue 102 can climb onto the side wall of the wafer 104.

[0064] Specifically, the height of the second layer of glue climbing on the side wall of the wafer is not greater than 90% of the thickness of the wafer. The direction in which the second layer of glue climbs on the side wall of the wafer is from the back surface of the wafer to the upper surface of the wafer, and the upper surface of the wafer is opposite to the back surface of the wafer. In this embodiment, the thickness of the wafer can be appropriately increased to facilitate controlling the height of the second layer of glue formed by the dispensing process climbing on the side wall of the wafer, and the contact area between the side wall of the wafer and the second layer of glue can also be increased to improve the heat dissipation capacity.

[0065] Such as Figure 2As shown, it is a cross-sectional view of the die bonding structure according to the second embodiment of the present invention. The die bonding structure includes a substrate 201, a first layer of glue 202, a second layer of glue 203, and a wafer 204. Among them, the first surface of the substrate is flat. The back surface of the wafer 204 is pasted on the first surface of the substrate 201 through the first layer of glue 202. The second layer of glue 203 covers the side surface of the first layer of glue 202 and the side wall of the wafer 204. Among them, the height at which the second layer of glue 203 climbs on the side wall of the wafer is not greater than 90% of the thickness of the wafer. The direction in which the second layer of glue 203 climbs on the side wall of the wafer is the direction extending from the back surface of the wafer to the upper surface of the wafer. The upper surface of the wafer is opposite to the back surface of the wafer. The second layer of glue 203 has a high thermal conductivity. Specifically, the thermal conductivity of the second layer of glue 203 is not less than 2 W / mK. The first layer of glue 202 has a uniform thickness and does not include voids. In this embodiment, the second layer of glue 203 is formed by a dispensing process, and the first layer of glue 202 is formed by brushing glue or pasting a DAF film on the back surface of the wafer. The first surface of the substrate 201 further includes a pad, that is, the wafer 204 is pasted on the pad on the first surface of the substrate.

[0066] The specific steps of the method for manufacturing the die bonding structure according to the second embodiment of the present invention are as follows:

[0067] Step 1: Form a first layer of glue 202 on the back surface of the wafer 204.

[0068] Specifically, the method for forming the first layer of glue 202 includes forming it by a brushing process or pasting a DAF film on the back surface of the wafer. The first layer of glue formed by these two processes is relatively easy to control the thickness of the glue layer, is not prone to generating voids, and can ensure the insulation isolation of the wafer. The first layer of glue is a non-conductive glue.

[0069] The brushing process is the same as the brushing process in the first embodiment.

[0070] Step S202: Paste the wafer 204 on the first surface of the substrate through the first layer of glue 202 with the back surface facing the first surface of the substrate 201.

[0071] Step S203: Form a second layer of glue 203 covering the side wall of the wafer 204 by a dispensing process.

[0072] Specifically, the dispensing process is to directly coat the glue on the side wall of the wafer by using pressure to transfer the glue material in the syringe or other transfer methods. The second layer of glue further covers the side surface of the first layer of glue. Among them, the second layer of glue is a non-conductive glue. The second layer of glue has a high thermal conductivity. Specifically, the thermal conductivity of the second layer of glue is not less than 2 W / mK.

[0073] Specifically, the height of the second layer of glue covering the side wall of the wafer is not greater than 90% of the thickness of the wafer. In this embodiment, the thickness of the wafer can be appropriately increased to facilitate controlling the height of the second layer of glue formed by the dispensing process climbing on the side wall of the wafer, or the contact area between the side wall of the wafer and the second layer of glue can be increased to improve the heat dissipation capacity.

[0074] According to the die bonding structure and its manufacturing method provided by the present invention, two layers of non-conductive glue are formed by different processes, so that the junction temperature generated by the wafer during operation can be conducted to the substrate through the first layer of glue under the wafer, and at the same time can be conducted to the substrate through the second layer of glue on the side wall of the wafer, thereby improving the heat dissipation capacity of the package. In addition, the first layer of glue formed by the glue brushing process and the method of attaching the DAF film has a uniform thickness and is not prone to voids, and can provide good insulation and isolation for the wafer.

[0075] As Figure 3 shown, it is a cross-sectional view of the die bonding structure according to the third embodiment of the present invention. The die bonding structure includes a substrate 301, a first layer of glue 302, a second layer of glue 303, and a wafer 304. Different from the first embodiment of the present invention, the first surface of the substrate 301 in this embodiment includes a groove, and the wafer 304 is installed in the groove. Other structures are the same as those in the first embodiment and will not be described herein again. In this embodiment, the size of the groove is sufficient to accommodate the lateral width of the wafer, that is, at least part of the thickness of the wafer 304 is located in the groove, that is, the upper surface of the wafer 304 is higher than the top of the groove. The wafer 304 is pasted on the bottom of the groove through the first layer of glue 302 and the second layer of glue 303. The second layer of glue 303 not only climbs on the side wall of the wafer but also fills the gap between the groove and the wafer. In this embodiment, the groove is preferably a structure with a narrower bottom and a wider top. Of course, those skilled in the art can also choose other suitable structures, which are not limited herein.

[0076] The substrate structure of this embodiment is also applicable to the die bonding structure in the second embodiment of the present invention, that is, the wafer 204 can also be pasted on the bottom of the groove on the first surface of the substrate only through the first layer of glue 302, and the second layer of glue 303 only covers the side surface of the first layer of glue 302 and the side wall of the wafer 204.

[0077] According to the third aspect of the present invention, the difference between the manufacturing method of the die bonding structure according to the third embodiment of the present invention and the first embodiment is that before forming the first layer of glue and the second layer of glue, a groove is first formed on the first surface of the substrate 301, and the groove is formed by chemical etching or mechanical indentation. Other process steps are the same as those in the first embodiment and will not be described herein again.

[0078] The die bonding structure provided in this embodiment shortens the distance between the periphery of the chip and the pads by forming a groove on the first surface of the substrate and mounting the die in the groove, that is, shortens the heat dissipation path on the side of the die, and further improves the heat dissipation capacity.

[0079] As described above in the embodiments according to the present invention, these embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the above description. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and its modified use based on the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A die bonding structure, comprising: A substrate, A wafer located on the first surface of the substrate, A first layer of glue on the back surface of the wafer, and A second layer of glue covering at least the sidewalls of the wafer, Characterized in that the wafer is pasted on the first surface of the substrate at least through the first layer of glue; The first layer of glue and the second layer of glue are different. Among them, both the first layer of glue and the second layer of glue are set as non-conductive glue. The second layer of glue has a high thermal conductivity, and the thermal conductivity of the second layer of glue is not less than 2W / mK; The first layer of glue and the second layer of glue are formed by different processes. Among them, the first layer of glue is formed by the process of brushing glue or by pasting a DAF film on the back surface of the wafer, so that there are no voids in the first layer of glue and the first layer of glue has a uniform thickness; The second layer of glue is formed by the process of dispensing glue.

2. The die bonding structure according to claim 1, wherein The second layer of glue is also located on the first surface of the substrate, and the wafer is pasted on the first surface of the substrate through the first layer of glue and the second layer of glue.

3. The die bonding structure according to claim 1, wherein The first surface of the substrate is set to be flat.

4. The die bonding structure according to claim 1, wherein The first surface of the substrate includes a groove, and the wafer is mounted in the groove.

5. The die bonding structure according to claim 4, wherein The upper surface of the wafer is higher than the top of the groove, and the upper surface of the wafer is opposite to the back surface of the wafer.

6. The die bonding structure according to claim 4, wherein, The groove is in the shape of being narrow at the bottom and wide at the top.

7. The die bonding structure according to claim 4, wherein The groove is formed by etching or mechanical indentation.

8. The die bonding structure according to claim 1, wherein, The height of the second layer of glue climbing on the sidewall of the wafer is not greater than 90% of the thickness of the wafer. The direction in which the second layer of glue climbs on the sidewall of the wafer is the direction extending from the back surface of the wafer to the upper surface of the wafer, and the upper surface of the wafer is opposite to the back surface of the wafer.

9. The die bonding structure according to claim 1, wherein The first surface of the substrate includes a pad, and the wafer is pasted on the pad.

10. A manufacturing method of a die bonding structure, comprising: Providing a wafer and a substrate; Forming a first layer of glue on the back surface of the wafer; Forming a second layer of glue covering at least the sidewalls of the wafer; And Pasting the wafer on the first surface of the substrate at least through the first layer of glue; The processes of forming the first layer of glue and forming the second layer of glue are different. Among them, the first layer of glue is formed by the process of brushing glue or by pasting a DAF film on the back surface of the wafer, so that there are no voids in the first layer of glue and the first layer of glue has a uniform thickness; Using the dispensing process to form the second layer of glue covering the sidewalls of the wafer; The first layer of glue and the second layer of glue are different. Among them, both the first layer of glue and the second layer of glue are set as non-conductive glue. The second layer of glue has a high thermal conductivity, and the thermal conductivity of the second layer of glue is not less than 2W / mK.

11. The method according to claim 10, wherein The second layer of glue is also formed on the first surface of the substrate, and the wafer is pasted on the first surface of the substrate through the first layer of glue and the second layer of glue.

12. The method according to claim 11, wherein The step of forming the second layer of glue includes: Using the dispensing process to form a second layer of glue on the first surface of the substrate; When pasting the wafer on the first surface of the substrate including the second layer of adhesive, a certain pressure is applied so that part of the second layer of adhesive can creep onto the side wall of the wafer.

13. The method according to claim 12, characterized in that, Before pasting the wafer on the first surface of the substrate, the second layer of adhesive is not cured.

14. The method according to claim 10, characterized in that, The first surface of the substrate is set to be flat.

15. The method according to claim 10, characterized in that, The first surface of the substrate includes a groove, and the wafer is mounted in the groove.

16. The method according to claim 15, wherein The groove is formed by etching or mechanical indentation.

17. The method according to claim 10, wherein The height of the second layer of adhesive creeping on the side wall of the wafer is not greater than 90% of the thickness of the wafer. The direction in which the second layer of adhesive creeps on the side wall of the wafer is the direction extending from the back surface of the wafer to the upper surface of the wafer, and the upper surface of the wafer is opposite to the back surface of the wafer.

18. The method according to claim 10, wherein The upper surface of the substrate includes pads, and the wafer is pasted on the pads.

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