Method of providing bumps on substrate

Abstract

The invention relates to a method for arranging a bump on a substrate, which comprises the following steps of: providing a substrate with at least one concave part on one surface; arranging a first metal layer on the surface of the base material, and filling the concave part on the base material with the first metal layer; arranging a second metal layer on the first metal layer; arranging at least one bump on a partial region of the second metal layer; etching the second metal layer which is not shielded by the bump through a plasma; and removing the first metal layer which is not shielded by the convex block and the first metal layer which is positioned in the concave part through etching liquid. According to the method provided by the invention, the metal in the concave part of the base material can be effectively removed, and the bump structure on the base material can be prevented from being damaged in the etching process.

Description

Technical Field

[0001] The invention relates to a method for setting a bump on a substrate, which can effectively remove the metal inside the concave part of the substrate and avoid damaging the bump structure on the substrate during the etching process. Background Art

[0002] Flip chip packaging is a packaging technology that flips the semiconductor chip over to align the bumps on the semiconductor chip with the pads on the substrate and solder them. Compared with the traditional packaging method of placing the semiconductor chip on the substrate and then connecting it with wires, flip chip packaging can provide higher connection density, lower signal delay, better heat dissipation and smaller package size.

[0003] In the flip-chip packaging structure, the bumps set on the semiconductor chip are like a small bridge connecting the two worlds, which is used to tightly combine the semiconductor chip with the external substrate, so that the semiconductor chip can be connected to the external circuit or chip through the substrate to perform its function.

[0004] The method for making the bump mainly includes processes such as thin film deposition, exposure and development, and etching, and is set on a partial area on the semiconductor chip.

[0005] In practical applications, an under-bump metallurgy (UBM) is usually set between the bump and the semiconductor chip. The main function of the UBM is to ensure the reliability of the electrical connection between the semiconductor chip and the bump and improve the overall reliability of the package. In addition, the UBM can also be used to prevent the material of the semiconductor chip and the material of the bump from diffusing with each other to avoid affecting the performance of the semiconductor chip.

[0006] Although the bump and UBM are tiny, they play a vital role in semiconductor packaging. With the continuous development of the semiconductor industry, the technology of bump and UBM is also constantly innovating to meet the needs of increasingly complex electronic products. Summary of the invention

[0007] The present invention provides a method for setting a bump on a substrate, which is particularly suitable for setting a bump and a metal under the bump on a substrate having at least one concave portion. The manufacturing method of the present invention can effectively remove the metal inside the concave portion of the substrate, and can avoid damaging the bump structure set on the substrate during the etching process.

[0008] One object of the present invention is to provide a method for setting a bump on a substrate, firstly, a first metal layer or a hole filling layer is set on the surface and the concave part of the substrate, so that a second metal layer can be set on the relatively flat first metal layer. Then, the second metal layer and the first metal layer are etched respectively in two stages by plasma and etching liquid, which can reduce the excessive damage to the bump in the process of removing the second metal layer and the first metal layer, and is conducive to maintaining the integrity of the bump structure.

[0009] One purpose of the present invention is to provide a method for setting a bump on a substrate, firstly, a photoresist shielding unit is set at a specific position of the substrate to define and reserve a position for setting the bump later. Then, a hole-filling layer is set on the surface of the substrate where the photoresist shielding unit is not set, wherein the hole-filling layer can be used to fill the concave portion on the substrate. A first metal layer can be set on the hole-filling layer with better flatness, and a second metal layer can be set on the first metal layer. By setting the photoresist shielding unit, there will be no hole-filling layer with a large thickness between the bump and the substrate or the metal pad, which is beneficial to reduce the impedance between the bump and the substrate or the metal pad.

[0010] In order to achieve the above-mentioned purpose, the present invention proposes a method for setting a bump on a substrate, comprising: providing a substrate, wherein a surface of the substrate has at least one recess; setting a first metal layer on the surface of the substrate and in the recess; setting a second metal layer on the first metal layer; setting at least one bump on a partial area of ​​the second metal layer; using a plasma to remove the second metal layer not blocked by the bump; and using an etching solution to remove the first metal layer not blocked by the bump and the first metal layer located in the recess.

[0011] The present invention proposes another method for setting a bump on a substrate, comprising: providing a substrate, wherein a surface of the substrate has at least one recess; setting at least one photoresist shielding unit on a portion of the surface of the substrate; setting a hole-filling layer on the surface of the substrate and in the recess; removing the photoresist shielding unit set on the substrate and forming at least one exposed portion on the substrate; setting a first metal layer on the hole-filling layer and the exposed portion; setting a second metal layer on the first metal layer; setting at least one bump on a portion of the second metal layer; using a plasma to remove the second metal layer not blocked by the bump; using plasma or a first etching solution to remove the first metal layer not blocked by the bump; and using a second etching solution to remove the hole-filling layer not blocked by the bump and the hole-filling layer located in the recess.

[0012] In one embodiment of the method for providing a bump on a substrate, the bump comprises an alloy of silver and gold.

[0013] In an embodiment of the method for providing a bump on a substrate, the first metal layer comprises titanium, a titanium alloy, a tungsten alloy or an alloy of titanium and tungsten.

[0014] In an embodiment of the method for providing a bump on a substrate, the second metal layer comprises gold or a gold alloy.

[0015] In an embodiment of the method for disposing a bump on a substrate, the substrate includes at least one metal pad, and the bump overlaps the metal pad.

[0016] In an embodiment of the method for disposing a bump on a substrate, the substrate includes at least one metal pad, and the bump and the exposed portion overlap with the metal pad.

[0017] The method for arranging a bump on a substrate of the present invention has the following advantages: the metal in the concave portion of the substrate can be effectively removed, and the bump structure on the substrate can be prevented from being damaged during the etching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A cross-sectional schematic diagram of a manufacturing process of a method for providing a bump on a substrate according to an embodiment of the present invention (I); Figure 2 A cross-sectional schematic diagram (II) of a manufacturing process of a method for providing a bump on a substrate according to an embodiment of the present invention; Figure 3 A cross-sectional schematic diagram of a manufacturing process of a method for providing a bump on a substrate according to an embodiment of the present invention (III); Figure 4 A cross-sectional schematic diagram (IV) of a manufacturing process of a method for providing a bump on a substrate according to an embodiment of the present invention; Figure 5 A cross-sectional schematic diagram (I) of a manufacturing process of another embodiment of a method for providing a bump on a substrate according to the present invention; Figure 6 A cross-sectional schematic diagram (II) of a manufacturing process of another embodiment of a method for providing a bump on a substrate according to the present invention; Figure 7 A cross-sectional schematic diagram (III) of a manufacturing process of another embodiment of a method for providing a bump on a substrate according to the present invention; Figure 8 A cross-sectional schematic diagram (IV) of a manufacturing process of another embodiment of a method for providing a bump on a substrate according to the present invention; Fig. 9 A cross-sectional schematic diagram (V) of a manufacturing process of another embodiment of a method for providing a bump on a substrate according to the present invention; Fig.10 FIG6 is a cross-sectional schematic diagram of a manufacturing process of another embodiment of a method for setting a bump on a substrate according to the present invention.

[0019] Description of Reference Numerals 11: substrate; 111: concave part; 112: surface; 12: light blocking shielding unit; 121: exposed part; 13: Metal pad; 15: Under bump metal; 151: first metal layer; 153: second metal layer; 155: hole filling layer; 17: Bump. DETAILED DESCRIPTION

[0020] Figures 1 to 4 The cross-sectional view of the manufacturing process of an embodiment of the method for setting a bump on a substrate of the present invention is as follows: First, a substrate 11 is provided, wherein a surface 112 of the substrate 11 has at least one concave portion 111, for example, the concave portion 111 can be a groove or a concave hole.

[0021] In one embodiment of the present invention, the substrate 11 may be a semiconductor substrate for manufacturing semiconductor devices, such as a silicon substrate, a silicon germanium substrate, a sapphire substrate, a silicon carbide substrate, a gallium arsenide substrate, or a silicon-on-insulator (SOI) substrate, etc. At least one semiconductor device (not shown) may be disposed inside or on the surface of the substrate 11, for example, the semiconductor device may be various forms of transistors, resistors, diodes, capacitors, inductors, and other components.

[0022] In addition, an interconnect structure (not shown) may be disposed on the substrate 11, wherein the interconnect structure includes metal wires and vias, etc., and is electrically connected to the semiconductor device. The semiconductor device and the interconnect structure are not the focus of the present invention, and therefore are not drawn in detail in the drawings.

[0023] At least one metal pad 13 is disposed on a partial area of ​​the substrate 11, wherein the metal pad 13 can be connected to the semiconductor device through an interconnect structure. For example, the metal pad 13 may include aluminum, copper, silver, gold, nickel, tungsten or an alloy of the aforementioned materials. The metal pad 13 may be a single-layer or multi-layer structure.

[0024] like Figure 1 As shown, a first metal layer 151 is disposed on the surface 112 and in the recess 111 of the substrate 11. The surface 112 of the substrate 11 has the recess 111 and / or the metal pad 13, and the first metal layer 151 covers the recess 111 and the metal pad 13 disposed on the surface 112. Specifically, the first metal layer 151 is located in the recess 111 of the substrate 11 and is used to fill the recess 111, so that the first metal layer 151 located above the recess 111 and the surface 112 of the substrate 11 has a similar height or flatness. For example, the thickness of the first metal layer 151 can be greater than.

[0025] In one embodiment of the present invention, after the first metal layer 151 is disposed, the first metal layer 151 may be further planarized to make the surface of the first metal layer 151 more flat.

[0026] In practical applications, the first metal layer 151 can be formed on the surface 112 of the substrate 11 by physical vapor deposition or chemical vapor deposition. In one embodiment of the present invention, the first metal layer 151 includes but is not limited to titanium, titanium alloy, tungsten alloy or titanium-tungsten alloy.

[0027] Before disposing the first metal layer 151 on the surface 112 of the substrate 11 , the substrate 11 is usually thoroughly cleaned to remove impurities such as organic matter and oxides remaining on the surface 112 of the substrate 11 to ensure good bonding between the first metal layer 151 and the substrate 11 .

[0028] After the first metal layer 151 is disposed, a second metal layer 153 may be further disposed on the first metal layer 151. In practical applications, the second metal layer 153 may be disposed on the surface of the first metal layer 151 using a physical vapor deposition process or a chemical vapor deposition process. In one embodiment of the present invention, the second metal layer 153 includes but is not limited to gold or a gold alloy.

[0029] Since the first metal layer 151 fills the concave portion 111 on the surface 112 of the substrate 11 , the second metal layer 153 can be disposed on the first metal layer 151 with higher flatness.

[0030] like Figure 2 As shown, at least one bump 17 is disposed on a partial area of ​​the second metal layer 153. In one embodiment of the present invention, the bump 17 may be disposed at a position overlapping with the metal pad 13, for example, the bump 17 may be disposed above the metal pad 13, wherein the first metal layer 151 and the second metal layer 153 are stacked between the bump 17 and the metal pad 13.

[0031] In practical applications, a shielding photoresist may be formed on a part of the second metal layer 153 by exposure and development to define the location and pattern of the bump 17 on the second metal layer 153. For example, the surface of the second metal layer 153 above the metal pad 13 is not provided with a shielding photoresist. Then, through a deposition process, the bump 17 is formed on the second metal layer 153 where the shielding photoresist is not provided. For example, the bump 17 may be provided on the surface of the second metal layer 153 that is not shielded by the photoresist by chemical vapor deposition, physical vapor deposition or electroplating. After the bump 17 is provided, the shielding photoresist on the second metal layer 153 may be removed.

[0032] According to the requirements of the process, the materials for making the bump 17 may include tin alloy, gold, copper alloy, nickel, silver and other materials. Among them, the bump 17 made of gold has the advantages of excellent metallic properties, corrosion resistance, high stability and low contact resistance, and is therefore widely used in high-frequency and high-speed components, high-reliability products and drive circuits. However, the bump 17 made of gold also has disadvantages such as high cost, easy cracking and difficult welding.

[0033] In order to improve the disadvantages of the gold bump 17, in one embodiment of the present invention, it is proposed to use a silver-gold alloy to make the bump 17, which can greatly reduce the production cost of the bump 17 without affecting the performance of the bump 17. For example, the weight percentage of silver in the bump 17 can be between 30% and 90%.

[0034] After the bumps 17 are disposed, the second metal layer 153 and the first metal layer 151 that are not shielded by the bumps 17 may be removed.

[0035] If only an etching solution is used to etch the second metal layer 153 and / or the first metal layer 151 that are not shielded by the bump 17, the etching solution used to etch the second metal layer 153 may damage the structure of the bump 17. For example, when the bump 17 includes a gold-silver alloy and the second metal layer 153 is gold or a gold alloy, if aqua regia or potassium iodide is used to etch the second metal layer 153, the silver in the bump 17 will be etched at the same time, and a plurality of holes will be formed on the bump 17. This will not only cause the structure of the bump 17 to be unstable, but also may reduce the metal ratio of the bump 17.

[0036] On the contrary, if plasma is simply used to remove the second metal layer 153 and / or the first metal layer 151 that are not shielded by the bump 17, although it will not have a great impact on the structure of the bump 17, for example, no hole will be formed on the bump 17, but the plasma may not be able to completely remove the second metal layer 153 and / or the first metal layer 151 located in the recess 111. For example, the plasma may be blocked by the recess 111.

[0037] To this end, the present invention further proposes that Figure 3 As shown, plasma is used to remove the second metal layer 153 that is not blocked by the bump 17 , for example, coupled inductive plasma (ICP) is used to remove the second metal layer 153 that is not overlapped with the bump 17 .

[0038] Because the first metal layer 151 is firstly disposed on the surface 112 of the substrate 11 before the second metal layer 153 is disposed, wherein the first metal layer 151 is located in the concave portion 111 of the substrate 11 to fill the concave portion 113 and form a relatively flat first metal layer 151 on the surface 112 of the substrate 11. Therefore, the second metal layer 153 is disposed on the relatively flat first metal layer 151, for example, the surface of the first metal layer 151 has no depressions or protrusions, and the second metal layer 153 not blocked by the bumps 17 can be completely removed by using plasma.

[0039] like Figure 4 As shown, after removing the second metal layer 153 , the first metal layer 151 not blocked by the bump 17 can be removed by etching solution, wherein the etching solution can completely remove the first metal layer 151 located on the surface 112 of the substrate 11 and in the recess 111 .

[0040] In practical applications, an appropriate etching solution can be selected according to the material of the first metal layer 151. For example, when the material of the first metal layer 151 is titanium, titanium alloy, or titanium tungsten and gold, hydrofluoric acid, hydrofluoric acid and hydrogen peroxide, or hydrofluoric acid and nitric acid can be used to etch the first metal layer 151. The etching solution used to etch the first metal layer 151 will not etch the bump 17 made of gold-silver alloy, and can maintain the integrity and metal ratio of the bump 17 structure.

[0041] In addition, the two-stage etching process can reduce the etching time of the etching solution, which is beneficial to reduce the action time of the etching solution and the first metal layer 151 under the bump 17 to avoid a more serious undercutting around the first metal layer 151 under the bump 17.

[0042] After completing the two-stage etching steps, the step of setting the bump 17 on the substrate 11 is completed, wherein the stacked first metal layer 151 and the second metal layer 153 exist only between the bump 17 and the substrate 11. The first metal layer 151 and the second metal layer 153 stacked under the bump 17 can be defined as under-bump metallurgy 15 (UBM), which can be used to ensure the reliability of the electrical connection between the substrate 11 and the bump 17, and can be used to prevent the materials of the substrate 11 and the bump 17 from diffusing into each other.

[0043] Figures 5 to 10 A cross-sectional diagram of another embodiment of the method for setting a bump on a substrate of the present invention is shown in FIG. First, a substrate 11 is provided, wherein a surface 112 of the substrate 11 has at least one concave portion 111 , such as a groove or a concave hole.

[0044] In practical applications, when the depth of the concave portion 111 on the substrate 11 is large, Figure 1 The thickness of the first metal layer 151 used to fill the recess 111 will also increase, so that Figure 4 As the thickness of the first metal layer 151 between the bump 17 and the metal pad 13 increases, the impedance between the bump 17 and the metal pad 13 may increase.

[0045] In addition, when the thickness of the first metal layer 151 is larger, the time for the etching solution to etch the first metal layer 151 will also increase, so as to completely remove the first metal layer 151 on the surface 112 of the substrate 11 and in the recess 111. As a result, the action time of the etching solution on the first metal layer 151 below the bump 17 will also increase, and more serious undercutting may be formed around the first metal layer 151 below the bump 17. When the undercutting area is too large, it will cause the line width to be smaller than the expected line width, and the bonding between the bump 17 and the metal pad 13 may be weakened, thereby reducing the reliability of subsequent products.

[0046] In order to avoid the above problems, another method of providing the bumps 17 on the substrate 11 is proposed in the embodiment of the present invention, such as Figure 5 As shown, at least one light-blocking shielding unit 12 is disposed on a surface 112 of a portion of the substrate 11. In one embodiment of the present invention, the surface 112 of the substrate 11 has a metal pad 13, and the light-blocking shielding unit 12 can be disposed on the metal pad 13 of the substrate 11. For example, the light-blocking shielding unit 12 can be disposed on the surface of the metal pad 13 by an exposure and development process.

[0047] Then, a hole-filling layer 155 is disposed on the surface 112 of the substrate 11. The surface 112 of the substrate 11 has a concave portion 111, and the hole-filling layer 155 is disposed on the surface 112 of the substrate 11 that is not shielded by the photoresist shielding unit 12, and covers the concave portion 111 of the substrate 11. For example, the thickness of the hole-filling layer 155 may be greater than. Specifically, the hole-filling layer 155 is located in the concave portion 111 of the substrate 11 and is used to fill the concave portion 111, wherein the hole-filling layer 155 located above the concave portion 111 and the surface 112 of the substrate 11 has a similar height or flatness. In one embodiment of the present invention, after the hole-filling layer 155 is disposed, the hole-filling layer 155 may be further planarized so that the surface of the hole-filling layer 155 is flatter.

[0048] like Figure 6 As shown, the light-resistance shielding unit 12 disposed on the substrate 11 is removed, and at least one exposed portion 121 is formed on the substrate 11. For example, after the light-resistance shielding unit 12 is removed, the metal pad 13 originally shielded by the light-resistance shielding unit 12 will be exposed.

[0049] like Figure 7As shown, a first metal layer 151 is disposed on the hole filling layer 155 and the exposed portion 121. For example, the first metal layer 151 is disposed on the hole filling layer 155 and the metal pad 13.

[0050] Then, a second metal layer 153 is disposed on the first metal layer 151. In practical applications, the hole-filling layer 155, the first metal layer 151, and the second metal layer 153 can be disposed by a physical vapor deposition process or a chemical vapor deposition process. For example, the material of the first metal layer 151 includes but is not limited to titanium, titanium alloy, tungsten alloy, or titanium-tungsten alloy, the material of the second metal layer 153 includes but is not limited to gold or gold alloy, and the material of the hole-filling layer 155 includes titanium, titanium alloy, tungsten alloy, tungsten alloy, aluminum, aluminum alloy, or aluminum-copper alloy.

[0051] After the first metal layer 151 and the second metal layer 153 are disposed, at least one bump 17 is disposed on a partial area of ​​the second metal layer 153. In one embodiment of the present invention, the bump 17 may be disposed at a position overlapping the metal pad 13 and the exposed portion 121, for example, the bump 17 may be disposed above the metal pad 13, wherein the first metal layer 151 and the second metal layer 153 are stacked between the bump 17 and the metal pad 13.

[0052] like Figure 8 As shown, plasma is used to remove the second metal layer 153 that is not blocked by the bump 17 , for example, coupled inductive plasma (ICP) is used to remove the second metal layer 153 that is not overlapped with the bump 17 .

[0053] Since the first metal layer 151 and the second metal layer 153 are disposed on the relatively flat hole-filling layer 155 , for example, the surface of the first metal layer 151 has no depressions or protrusions, and the second metal layer 153 not blocked by the bumps 17 can be completely removed by plasma.

[0054] like Fig. 9 As shown, after removing the second metal layer 153, the first metal layer 151 not blocked by the bump 17 can be removed by the first etching solution. In different embodiments, since the first metal layer 151 is disposed on a relatively flat hole-filling layer 155, plasma can also be used to completely remove the first metal layer 151 not blocked by the bump 17. like Fig.10 As shown, after removing the first metal layer 151, the hole-filling layer 155 not blocked by the bump 17 can be removed by a second etching solution, wherein the second etching solution can completely remove the hole-filling layer 155 located on the surface 112 of the substrate 11 and in the recess 111. In practical applications, if the materials of the first metal layer 151 and the hole-filling layer 155 are the same or similar, the first etching solution and the second etching solution can be the same etching solution.

[0055] By using the manufacturing method described in the embodiment of the present invention, a too thick first metal layer 151 or a filling layer 155 will not be generated between the bump 17 and the metal pad 13 and / or the substrate 11, so that the impedance between the bump 17 and the metal pad 13 will not increase.

[0056] In practical applications, the first metal layer 151 and the hole-filling layer 155 may be made of different materials, and the second etching solution used to etch the hole-filling layer 155 may not etch the first metal layer 151, or may have a lower etching rate on the first metal layer 151. This will avoid serious undercutting around the first metal layer 151 between the bump 17 and the metal pad 13, which is beneficial to improving the stability of the connection between the bump 17 and the metal pad 13 and increasing the reliability of the subsequent products.

[0057] Compared to Figures 1 to 4 The method of making Figures 5 to 10 The metal properties of the bump 17 and the under-bump metal 15 produced by the manufacturing method are better, but at least one yellow light process step and at least one photomask need to be added, which will inevitably increase the manufacturing cost. In actual application, the user can choose one of the above methods to set the under-bump metal 15 and the bump 17 on the substrate 11 according to the product requirements or the depth of the concave portion 111 on the substrate 11.

[0058] The above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. That is, all equivalent changes and modifications to the shape, structure, characteristics and spirit described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

Claims

1. A method for providing a bump on a substrate, characterized in that: include: A substrate, wherein a surface of the substrate has at least one concave portion; Disposing a first metal layer on the surface of the substrate and in the recess; Disposing a second metal layer on the first metal layer; Disposing at least one bump on a partial area of ​​the second metal layer; Using a plasma to remove the second metal layer not blocked by the bump; and An etching solution is used to remove the first metal layer not blocked by the bump and the first metal layer located in the concave portion.

2. The method for providing a bump on a substrate according to claim 1, wherein: The bump includes an alloy of silver and gold.

3. The method for providing a bump on a substrate according to claim 2, wherein: The first metal layer includes titanium, titanium alloy, tungsten alloy or titanium-tungsten alloy.

4. The method for providing a bump on a substrate according to claim 3, wherein: The second metal layer includes gold or a gold alloy.

5. The method for providing a bump on a substrate according to claim 2, wherein: The substrate includes at least one metal pad, and the bump overlaps the metal pad.

6. A method for providing a bump on a substrate, characterized in that: include: Providing a substrate, wherein the substrate has at least one concave portion on a surface thereof; Disposing at least one light blocking unit on a portion of the surface of the substrate; Disposing a hole-filling layer on the surface of the substrate and in the concave portion; Removing the light-resistance shielding unit disposed on the substrate and forming at least one exposed portion on the substrate; Disposing a first metal layer on the hole-filling layer and the exposed portion; Disposing a second metal layer on the first metal layer; Disposing at least one bump on a partial area of ​​the second metal layer; Using a plasma to remove the second metal layer not blocked by the bump; Using the plasma or a first etching solution to remove the first metal layer not blocked by the bump; and A second etching solution is used to remove the hole-filling layer not blocked by the bump and the hole-filling layer in the concave portion.

7. The method for providing a bump on a substrate according to claim 6, wherein: The bump includes an alloy of silver and gold.

8. The method for providing a bump on a substrate according to claim 7, wherein: The first metal layer includes titanium, titanium alloy, tungsten alloy or titanium-tungsten alloy.

9. The method for providing a bump on a substrate according to claim 8, wherein: The second metal layer includes gold or a gold alloy.

10. The method for providing a bump on a substrate according to claim 6, wherein: The substrate includes at least one metal pad, and the bump and the exposed portion overlap the metal pad.

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