Flip chip method and flip chip

Abstract

The application discloses a chip flip method and a flip chip. The chip flip method comprises the following steps: providing a substrate and a chip, wherein the chip is provided with a first through hole; forming an insulating layer on the substrate, and the surface of the insulating layer is parallel to the surface of the substrate; etching the insulating layer to form a second through hole corresponding to the first through hole; aligning the first through hole and the second through hole, and then adhering the chip to the insulating layer; and filling a supporting material into the first through hole to form a supporting column in the space defined by the first through hole and the second through hole, so as to obtain the flip chip. Since the supporting column is filled and formed in the space defined by the first through hole and the second through hole, and the insulating layer keeps the chip parallel to the substrate during the formation of the supporting column, the height of the supporting column is consistent, and the chip is kept parallel to the substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to flip chip technology field, in particular to a chip flip method and flip chip. BACKGROUND

[0002] The integrated circuit has higher and higher requirements for chip packaging technology, and the traditional wire bonding technology cannot meet the requirement of further miniaturization of chip packaging size, so the industry proposes many new packaging forms, among which, the chip flip technology has good electrical performance, thermal performance, high I / O pin density, small packaging size and other advantages, and stands out in the field of high-density packaging.

[0003] At present, the chip flip technology mainly constructs support columns (also called bumps) between the chip and the substrate to realize the bonding of the chip and the substrate. However, in some applications, in order to obtain some special design parameters, the chip and the substrate need to be parallel. However, the bump is formed by growing process on the chip or the substrate, and the height of the bump is not completely consistent due to the influence of process level, which causes the chip and the substrate to be unable to keep parallel after bonding. SUMMARY

[0004] The purpose of the present application is to provide a chip flip method and flip chip to solve the problem of non-parallel chip and substrate caused by the existing chip flip technology, which can make the height of the support column consistent and ensure the parallelism of the chip and the substrate.

[0005] To solve the above technical problems, the present application provides a chip flip method, comprising:

[0006] providing a substrate and a chip, wherein the chip has a patterned first via;

[0007] forming an insulating layer on the substrate, which is parallel to the surface of the substrate;

[0008] etching the insulating layer to form a second via corresponding to the first via;

[0009] aligning the first via and the second via, and then adhering the chip to the insulating layer;

[0010] filling support material through the first via to form a support column in the space defined by the first via and the second via, so as to obtain a flip chip.

[0011] Preferably, the method further comprises:

[0012] removing the insulating layer between the substrate and the chip.

[0013] Preferably, the step of filling support material through the first via comprises:

[0014] filling support material through the first through hole along a direction perpendicular to the surface of the chip;

[0015] or filling support material through the first through hole along a direction inclined to the surface of the chip.

[0016] Preferably, a metal pad exposed to the second through hole is further formed between the substrate and the insulating layer.

[0017] Preferably, the metal pad is formed before the insulating layer is formed, and the forming process of the metal pad is as follows:

[0018] forming a metal layer on the substrate;

[0019] etching the metal layer to form a metal pad corresponding to the first through hole.

[0020] Preferably, the metal layer is formed by layer-by-layer sputtering deposition of metal material.

[0021] Preferably, before the step of forming a metal layer on the substrate, the method further comprises:

[0022] sputtering cleaning the surface of the substrate.

[0023] Preferably, the support material has conductivity.

[0024] Preferably, the support material is filled by evaporation or sputtering process.

[0025] Preferably, the material of the insulating layer is photoresist.

[0026] Preferably, the first through hole is formed by laser drilling or etching, and the second through hole is formed by dry etching process.

[0027] Preferably, the projection of the first through hole on the substrate is located within the projection range of the second through hole on the substrate.

[0028] To solve the above technical problems, the application further provides a flip chip obtained by the flip chip method.

[0029] Different from the prior art, the flip chip method provided by the application forms an insulating layer on a substrate, forms a second through hole on the insulating layer, adheres the bottom surface of a chip with a patterned first through hole to the insulating layer, aligns the first through hole with the second through hole, and fills support material through the first through hole to form a support column. Since the support column is filled and formed within the space defined by the first through hole and the second through hole, and the insulating layer keeps the chip parallel to the substrate during the formation of the support column, the height of the support column is consistent, and the chip is kept parallel to the substrate.

[0030] The flip chip provided by the application is obtained according to the chip flip method, and belongs to the same inventive concept, thus has the same beneficial effects, which will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A flowchart of the chip flip method provided by the first embodiment of the application.

[0032] Figures 2a to 2f A cross-sectional view of the process of preparing the flip chip according to the chip flip method shown in Figure 1

[0033] Figure 3 A flowchart of the chip flip method provided by the first embodiment of the application.

[0034] Figures 4a to 4f A cross-sectional view of the process of preparing the flip chip according to the chip flip method shown in Figure 3 DETAILED DESCRIPTION

[0035] The specific embodiments of the application will be described in more detail below with reference to the accompanying drawings. The advantages and features of the application will be more apparent according to the following description and claims. It should be noted that the drawings are very simplified and use non-precise proportions, only to facilitate, clarify the purpose of assisting the description of the embodiments of the application.

[0036] In the description of the application, it should be understood that the terms "center", "upper", "lower", "left", "right" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only to facilitate the description of the application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation of the application.

[0037] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0038] Please refer to Figure 1 The first embodiment of the application provides a chip flip method, comprising the following steps:

[0039] S1: providing a substrate and a chip, wherein the chip has a patterned first via.

[0040] ​​The first through hole can be formed by laser drilling or etching. The shape of the first through hole can be any shape, and the present application preferably is circular. As shown in Figure 2a The chip 100 has a patterned first through hole 101.

[0041] S2: Forming an insulating layer on the substrate, the surface of which is parallel to the surface of the substrate.

[0042] The material of the insulating layer is preferably photoresist, and the insulating layer can be formed by coating photoresist. Specifically, the insulating layer can be formed by spin coating photoresist, so that the thickness of the insulating layer is uniform, and the surface can be guaranteed to be parallel to the surface of the substrate. As shown in Figure 2b The insulating layer 300 is formed on the substrate 200.

[0043] S3: Etching the insulating layer to form a second through hole corresponding to the first through hole.

[0044] The insulating layer can be etched by various etching processes, in order to ensure that the second through hole has a regular shape and no residue on the hole wall. In the present embodiment, the second through hole is formed by dry etching process, such as plasma etching or sputtering etching. The shape of the second through hole can also be any shape, and the present application preferably is the same shape as the first through hole. As shown in Figure 2c The second through hole 301 corresponding to the first through hole 101 is formed on the insulating layer 300.

[0045] S4: After aligning the first through hole and the second through hole, the chip is attached to the insulating layer.

[0046] Since the first through hole and the second through hole correspond one-to-one, the first through hole and the second through hole can be aligned. When aligning, the central axes of the first through hole and the second through hole can be adjusted, and when the central axes of the first through hole and the second through hole are aligned, the alignment of the first through hole and the second through hole is completed. Since the surface of the insulating layer is parallel to the surface of the substrate, and the chip is attached to the insulating layer, the bottom surface of the chip will be parallel to the surface of the substrate. As shown in Figure 2d The first through hole 101 is aligned with the second through hole 301, and the chip 100 is attached to the insulating layer 300.

[0047] S5: Filling the support material through the first through hole to form a support column in the space defined by the first through hole and the second through hole, to obtain a flip chip.

[0048] Wherein, since the chip is attached to the insulating layer, the first via and the second via are in communication with each other, and after the first via is filled with the support material, the support material will gradually fill the space defined by the first via and the second via, and finally form a support column. The bottom of the support column is combined with the substrate, and the top is combined with the hole wall of the first via, thereby realizing the support and fixation of the chip. Since the shape of the space defined by the first via and the second via is uniform, the height of the support column formed in the space is consistent, so that the chip connected to the substrate through the support column is guaranteed to be parallel to the substrate. As shown in Figure 2e the space defined by the first via 101 and the second via 301 forms a support column 400, which guarantees that the chip 100 and the substrate 200 are parallel.

[0049] In order to continuously grow the support column and avoid insufficient contact between the support column and the chip and / or the substrate, in the embodiment, the step of filling the support material through the first via includes:

[0050] filling the support material through the first via in a direction perpendicular to the surface of the chip;

[0051] or filling the support material through the first via in a direction inclined to the surface of the chip.

[0052] Wherein, filling the support material in a direction perpendicular to the surface of the chip can make the bottom of the second via fully contact the support material, and filling the support material in a direction inclined to the surface of the chip can make the sidewall of the first via and the second via fully contact the support material.

[0053] In addition to the support function, the support material also needs to realize the electrical connection between the chip and the substrate in some applications. In order to realize the electrical connection, in the embodiment, the support material can have conductivity, and the support material can be a substance that can conduct electricity, such as metal, alloy or compound. When filling the support material, evaporation or sputtering process can be used for filling.

[0054] In the embodiment, the flip chip method can further include:

[0055] S6: removing the insulating layer between the substrate and the chip.

[0056] Wherein, in some application requirements, it is necessary to remove the insulating layer after the support column is formed, for example, the substrate needs to have strong heat dissipation performance, and the existence of the insulating layer may affect the heat dissipation performance, so the insulating layer needs to be removed. As shown in Figure 2f after the insulating layer 300 is removed, only the support column 400 is left between the chip 100 and the substrate 200.

[0057] In order to further strengthen the supporting column, in the embodiment, the projection of the first through hole on the substrate is located in the projection range of the second through hole on the substrate. That is, the cross-sectional shape of the first through hole cannot exceed the coverage range of the cross-sectional shape of the second through hole on the geometric plane. For example, when the first through hole and the second through hole are both circular, the aperture of the first through hole is smaller than or equal to the aperture of the second through hole. As shown in FIG. 2, the aperture of the first through hole is smaller than the aperture of the second through hole, and the part of the finally formed supporting column in the second through hole and the part in the first through hole form a step, and the bottom surface of the chip is located on the step surface, so that the fixation of the chip is more stable. Since the aperture of the first through hole is smaller than the aperture of the second through hole, the difficulty of punching on the chip can be reduced, and chip breakage can be avoided.

[0058] The beneficial effects of the chip flip method of the embodiment are as follows:

[0059] 1. The smoothness of the cut of the first through hole is not required, and the cut can be allowed to be rough. In this way, not only can the difficulty of cutting be reduced, but also the surface friction of the cut can be increased, so that the supporting material is more easily attached to the hole wall of the first through hole;

[0060] 2. The supporting column is formed by filling the supporting material, so that the supporting column can grow continuously and can be in full contact with the chip and the substrate. When the supporting material has conductivity, the situation of electrical connection failure of the supporting column can be avoided;

[0061] 3. The insulating layer does not interfere with the electrical performance of the flip chip, so that when the insulating layer needs to be removed, the situation of incomplete removal of the insulating layer can be allowed.

[0062] The second embodiment of the application provides a chip flip method. The chip flip method of the second embodiment is based on the chip flip method of the first embodiment and includes all the technical features of the chip flip method of the first embodiment. The difference lies in that a metal pad exposed to the second through hole is further formed between the substrate and the insulating layer. The metal pad can be formed before the formation of the insulating layer or after the formation of the insulating layer. In the embodiment, the metal pad is preferably formed before the formation of the insulating layer. Please refer to Figure 3 , and the formation process of the metal pad is as follows:

[0063] S2B: Forming a metal layer on the substrate.

[0064] In the embodiment, the metal layer can be formed by layer-by-layer sputtering deposition of metal material. As shown in Figure 4a , a metal layer 500 is formed on the substrate 200.

[0065] S2C: Etching the metal layer to form a metal pad corresponding to the first through hole.

[0066] In the etching of the metal layer, a mask pattern can be used to cover the metal layer, and then the metal layer outside the mask pattern is etched, and the remaining metal layer forms the metal pad. As shown in Figures 4b to 4d After the metal layer 500 is etched, the metal pad 501 corresponding to the first via hole 101 on the chip 100 is formed, and after the second via hole 301 is formed on the insulating layer 300, the metal pad 501 is exposed in the second via hole 301.

[0067] After the metal pad is formed, since the metal pad is exposed in the second via hole, after the support column is formed, the bottom of the support column is combined with the metal pad, and when the support column has conductivity, the electrical connection with the metal pad can be realized. As shown in Figure 4e and 4f After the support column 400 is formed in the space defined by the first via hole 101 and the second via hole 301, the metal pad 501 is combined with the bottom of the support column 400.

[0068] In order to ensure that the metal layer is fully combined with the substrate, further, in the embodiment, before the step of forming the metal layer on the substrate, that is, step S2B, further includes:

[0069] S2A: sputtering cleaning is performed on the surface of the substrate.

[0070] Through sputtering cleaning, the oxide on the surface of the substrate can be removed, and the roughness of the surface of the substrate can be increased, so that the bonding force of the metal layer and the substrate can be improved.

[0071] The present application also provides a flip chip, which is obtained according to the chip flip method of the first embodiment or the second embodiment.

[0072] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", or "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0073] The above is only the preferred embodiment of the present application, and does not limit the present application in any way. Any person skilled in the art can make any form of equivalent replacement or modification of the technical solutions and technical content disclosed in the present application without departing from the scope of the technical solutions of the present application, and still belongs to the protection scope of the present application.

Claims

1. A chip flip-chip method, characterized in that, include: A substrate and a chip are provided, wherein the chip has a patterned first through-hole, the cut of the first through-hole having a roughness; An insulating layer with a surface parallel to the surface of the substrate is formed on the substrate by spin-coating photoresist; The insulating layer is etched to form a second through hole corresponding to the first through hole; After aligning the first through hole with the second through hole, the chip is attached to the insulating layer; By filling the first through hole with support material, a support pillar is formed within the space jointly defined by the first through hole and the second through hole to obtain a flip chip; The projection of the first through hole onto the substrate is located within the projection range of the second through hole onto the substrate.

2. The method according to claim 1, characterized in that, The method further includes: Remove the insulating layer between the substrate and the chip.

3. The method according to claim 1, characterized in that, The step of filling the support material through the first through hole includes: The first through-hole is filled with support material in a direction perpendicular to the chip surface; Alternatively, support material can be filled through the first through-hole along the direction of the inclined chip surface.

4. The method according to claim 1, characterized in that, A metal pad exposed to the second through-hole is also formed between the substrate and the insulating layer.

5. The method according to claim 4, characterized in that, The metal pads are formed before the insulating layer is formed, and the formation process of the metal pads is as follows: A metal layer is formed on the substrate; The metal layer is etched to form a metal pad corresponding to the first through hole.

6. The method according to claim 5, characterized in that, The metal layer is formed by layer-by-layer sputtering deposition of metal materials.

7. The method according to claim 5, characterized in that, Prior to the step of forming a metal layer on the substrate, the method further includes: The substrate surface is sputter-cleaned.

8. The method according to claim 1, characterized in that, The supporting material is conductive.

9. The method according to claim 8, characterized in that, The support material is filled using vapor deposition or sputtering processes.

10. The method according to claim 1, characterized in that, The first through hole is formed by laser drilling or etching, and the second through hole is formed by dry etching process.

11. A flip chip obtained by the chip flipping method according to any one of claims 1 to 10.

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