Bump structure of chip

Abstract

A bump structure of a chip comprises a substrate, a connecting pad, a protective layer, a reinforcing structure and a bump. The connecting pad is arranged on the substrate. The protective layer is arranged on the substrate and comprises an opening, and at least one part of the connecting pad is exposed out of the opening. The reinforcing structure is arranged on the connecting pad in the open hole. The bump is disposed on the protective layer and covers the reinforcing structure, and a flat surface is formed on the top surface of the bump. The invention provides a bump structure of a chip, which has better surface flatness.

Description

Technical Field

[0001] The invention relates to a bump structure, in particular to a bump structure of a chip. Background Art

[0002] Today's chips include bump structures, which are used to connect components such as substrates. Today's bump structures have poor surface flatness, which results in the bump structure being unable to be stably connected to the substrate, and the chip is easily peeled off the substrate or the electrical connection reliability is poor. How to improve the surface flatness of the bump structure is an urgent problem to be solved in the art. Summary of the invention

[0003] The present invention is directed to a bump structure of a chip, which has better surface flatness.

[0004] According to an embodiment of the present invention, a bump structure of a chip includes a substrate, a pad, a protective layer, a reinforcement structure and a bump. The pad is disposed on the substrate. The protective layer is disposed on the substrate and includes an opening, and the opening exposes at least a portion of the pad. The reinforcement structure is disposed on the pad in the opening. The bump is disposed on the protective layer and covers the reinforcement structure, and a flat surface is formed on the top surface of the bump.

[0005] In the bump structure of the chip according to the embodiment of the present invention, the upper surface of the reinforcement structure is flush with the top surface of the protection layer.

[0006] In the bump structure of the chip according to the embodiment of the present invention, the top surface of the bump includes a flat surface and a concave portion, and the concave portion is located at the edge of the bump.

[0007] In the bump structure of the chip according to the embodiment of the present invention, the distance between the bottom of the concave portion and the flat surface is less than 5 micrometers.

[0008] The bump structure of the chip according to the embodiment of the present invention further includes an under-ball metal layer, which covers the reinforcement structure and a portion of the protection layer.

[0009] In the bump structure of the chip according to the embodiment of the present invention, the bump is connected to the under ball metal layer.

[0010] In the bump structure of the chip according to the embodiment of the present invention, the material of the reinforcement structure is copper, palladium or vanadium.

[0011] In the bump structure of the chip according to the embodiment of the present invention, the Mohs hardness of the reinforcement structure is greater than or equal to 3.

[0012] In the bump structure of the chip according to the embodiment of the present invention, the material of the bump is gold.

[0013] The bump structure of the chip according to the embodiment of the present invention further includes a seed layer, and the seed layer is disposed between the reinforcement structure and the pad.

[0014] Based on the above, the bump structure of the chip of the present invention includes a reinforcement structure, and the bump covers the reinforcement structure. Thus, the reinforcement structure can provide support for the bump, so that the top surface of the bump forms a flat surface, thereby improving the surface flatness of the bump structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figures 1 to 5 is a schematic diagram of a manufacturing process of a bump structure of a chip according to an embodiment of the present invention. DETAILED DESCRIPTION

[0016] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0017] Figures 1 to 5 is a schematic diagram of a manufacturing process of a bump structure of a chip according to an embodiment of the present invention. Figures 1 to 5 Regarding the manufacturing process of the bump structure 100 of the chip 10 of the present embodiment, first, a wafer 200 is provided, and a pad 120 and a protective layer 130 are set on a wafer substrate 210 of the wafer 200. Two pads 120 are schematically shown here, but it is not limited to this. The protective layer 130 is partially connected to the pad 120. The protective layer 130 includes an opening 132, and the opening 132 exposes at least a portion of the pad 120. The material of the pad 120 is, for example, aluminum, but it is not limited to this.

[0018] The protective layer 130 of the present embodiment includes a passivation layer 136 and a first protective layer 137, that is, the protective layer 130 is a double-layer structure, but is not limited thereto. The passivation layer 136 is disposed on the wafer substrate 210 and is partially connected to the pad 120, and the first protective layer 137 covers the passivation layer 136 and is partially connected to the pad 120. The material of the first protective layer 137 is, for example, polyimide resin (PI), but is not limited thereto. In an embodiment not shown, the protective layer 130 is the passivation layer 136 and is a single-layer structure. In another embodiment not shown, the protective layer 130 may include a passivation layer 136, a first protective layer 137 and a second protective layer, and is a three-layer structure. The second protective layer may cover the first protective layer 137. The number of layers and thickness of the protective layer 130 may be changed according to actual needs.

[0019] like Figure 2As shown, after the pad 120 and the protective layer 130 are set, the seed layer 180 and the reinforcement structure 140 are set. The seed layer 180 is set on the portion of the pad 120 exposed from the opening 132. The reinforcement structure 140 is connected to the seed layer 180 and is set on the pad 120 in the opening 132, so that the seed layer 180 is set between the reinforcement structure 140 and the pad 120. The reinforcement structure 140 includes a lower surface 144 and an upper surface 142 opposite to each other. The lower surface 144 is connected to the pad 120 through the seed layer 180, and the upper surface 142 is flush with the top surface 134 of the protective layer 130. At this point, the reinforcement structure 140 is set.

[0020] The cross-sectional shape of the reinforcement structure 140 of the present embodiment is rectangular, but is not limited thereto. The height of the reinforcement structure 140 varies with the total height of the protective layer 130. The reinforcement structure 140 can be used for protective layers 130 of different heights and protective layers having a multi-layer structure such as a single layer, a double layer or a triple layer. The material of the reinforcement structure 140 can be a metal with a Mohs hardness greater than or equal to 3. The material of the reinforcement structure 140 can be selected from one of the materials such as copper, palladium or vanadium, or a combination thereof. For example, the material of the reinforcement structure 140 of the present embodiment is, for example, copper with a Mohs hardness of 3, and the material of the seed layer 180 is, for example, titanium / copper (Ti / Cu), but is not limited thereto.

[0021] like Figure 3 As shown, after the seed layer 180 and the reinforcement structure 140 are set, the ball bottom metal layer 160 is set. The ball bottom metal layer 160 covers the upper surface 142 and the side surface of the reinforcement structure 140, and covers at least a portion of the top surface 134 of the protection layer 130. Figure 4 As shown, after the bottom metal layer 160 is set, the bump 150 is set. The bump 150 is set on the protective layer 130 and connected to the bottom metal layer 160. The bump 150 covers the reinforcement structure 140, so that the reinforcement structure 140 supports the bump 150, so that the top surface 152 of the bump 150 can form a flat surface S1. The material of the bump 150 is, for example, gold, and the material of the bottom metal layer 160 is, for example, titanium tungsten / gold (TiW / Au). But it is not limited to this. After the bump 150 is set, the wafer 200 can be cut along the cutting line C to form a plurality of chips 10 ( Figure 5 ).

[0022] Figure 5 A bump structure 100 on a chip 10 of the present embodiment is schematically shown as an example. The bump structure 100 of the chip 10 includes a substrate 110, a pad 120 and a protective layer 130 disposed on the substrate 110, a seed layer 180, a reinforcement structure 140, an under ball metal layer 160 and a bump 150. The substrate 110 is formed by a cut wafer substrate 210.

[0023] The bump 150 and the reinforcement structure 140 can be regarded as a connector 170. Compared with the existing connector 170 made of pure gold (that is, without the reinforcement structure 140, the connector 170 is made of gold), the connector 170 formed by the reinforcement structure 140 made of copper and the bump 150 made of gold in this embodiment has better material hardness. The reinforcement structure 140 made of copper can also reduce the amount of gold used in the connector 170 to reduce costs.

[0024] The flat surface S1 of the bump 150 helps the chip 10 (bump 150) to be stably connected to other structures (e.g., substrate). For example, the chip 10 (bump 150) can be connected to a substrate (not shown) through anisotropic conductive paste (Anisotropic Conductive Paste, ACP). When the structural fluctuation of the top surface 152 of the bump 150 is too large, it will affect the connection between the bump 150 and the conductive particles in the anisotropic conductive paste, so that the chip 10 (bump 150) cannot be stably connected to the substrate through the anisotropic conductive paste, and it is easy to peel off from the substrate or electrically short-circuit. In this embodiment, since the bump 150 of the chip 10 has a flat surface S1 (i.e., the structural fluctuation is extremely small), the flat surface S1 of the bump 150 can be stably electrically connected to the conductive particles in the anisotropic conductive paste, so that the chip 10 can be stably combined with the substrate through the anisotropic conductive paste. The material of the substrate may be, for example, a glass substrate, a silicon wafer, a plastic substrate, a PCB substrate or other materials that can be bonded with anisotropic conductive adhesive.

[0025] like Figure 5 As shown, the top surface 152 of the bump 150 also includes a recess S2, which is located at the edge of the bump 150. The distance D between the bottom 154 of the recess S2 and the flat surface S1 is less than the diameter of the conductive particles in the anisotropic conductive adhesive. The diameter of the conductive particles in the anisotropic conductive adhesive is, for example, 5 microns, and the distance D is less than 5 microns. Specifically, the distance D is between 1 micron and 2 microns, which is much smaller than the diameter of the conductive particles, but is not limited to this. Therefore, the overall structural fluctuations of the top surface 152 (flat surface S1 and recess S2) of the bump 150 are still small. When the bump 150 is connected to the anisotropic conductive adhesive, the conductive particles can still be stably connected to the top surface 152 (flat surface S1 and recess S2) of the bump 150, so that the chip 10 and the substrate are stably combined.

[0026] In summary, the bump structure of the chip of the present invention includes a reinforcement structure, and the bump completely covers the reinforcement structure. Therefore, the reinforcement structure can provide structural support for the bump, so that the top surface of the bump forms a flat surface, thereby improving the surface flatness of the bump structure.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bump structure of a chip, characterized in that: include: substrate; A pad, disposed on the substrate; A protective layer, disposed on the substrate and comprising an opening, wherein the opening exposes at least a portion of the pad; A reinforcement structure disposed on the pad in the opening; as well as The bump is disposed on the protection layer and covers the reinforcement structure, and a flat surface is formed on the top surface of the bump.

2. The bump structure of the chip according to claim 1, characterized in that: The upper surface of the reinforcement structure is flush with the top surface of the protection layer.

3. The bump structure of the chip according to claim 1, characterized in that: The top surface of the bump includes the flat surface and a concave portion, and the concave portion is located at an edge of the bump.

4. The bump structure of the chip according to claim 3, characterized in that: The distance between the bottom of the recess and the flat surface is less than 5 micrometers.

5. The bump structure of the chip according to claim 1, characterized in that: It also includes a ball bottom metal layer, which covers the reinforcement structure and part of the protection layer.

6. The bump structure of the chip according to claim 5, characterized in that: The bump is connected to the under ball metal layer.

7. The bump structure of the chip according to claim 1, characterized in that: The reinforcement structure is made of copper, palladium or vanadium.

8. The bump structure of the chip according to claim 1, characterized in that: The Mohs hardness of the reinforcement structure is greater than or equal to 3.

9. The bump structure of the chip according to claim 1, characterized in that: The material of the bump is gold.

10. The bump structure of the chip according to claim 1, characterized in that: The invention also includes a seed layer, wherein the seed layer is arranged between the reinforcement structure and the pad.

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