Bump package structure and method for preparing bump package structure

Abstract

The embodiment of the present invention provides a bump package structure and a method for preparing the bump package structure, which relates to the field of semiconductor package technology. The bump package structure includes a chip, a first protective layer, a second protective layer, a third protective layer, a conductive metal layer, a conductive bump and a solder cap. The first protective layer is provided with a first opening, and the second protective layer is provided with a second opening. By providing the third opening on the third protective layer, the strength of the soldering structure can be enhanced during solder ball soldering, and the solder flank flow can be prevented to avoid bridging problems. At the same time, after the tin layer is electroplated, when soldering to the substrate, when the pad is a circuit or a solder ball, the third protective layer can limit the flow of solder, and during the reflow process and when the bottom filling glue is performed after the soldering process on the substrate, the bottom glue layer can be better filled into the third opening by capillary action, thereby improving the soldering effect.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular to a bump packaging structure and a method for preparing the bump packaging structure. Background Art

[0002] With the rapid development of the semiconductor industry, flip-chip packaging structures are widely used in the semiconductor industry. Flip-chip packaging uses bumps to make electrical connections between chips and substrates. Bumps include copper pillars, metal layers (UBM: under bump metalization), protective layers (polyimide), and tin caps (Sn Caps). After making the metal layer UBM, the excess metal layer needs to be etched away. Since the polyimide material is extremely easy to absorb water, the etching liquid on the UBM sidewall at the bottom of the metal pillar will remain, resulting in excessive corrosion and undercut openings at the bottom of the copper pillar bump. When the bumped chip is subjected to reliability testing, the copper pillar bump has the problem of falling off.

[0003] In addition, in the packaging process for the copper pillar bumps of the flip chip, the flip chip is welded on the substrate. As the spacing between the copper pillar bumps becomes smaller and smaller, the bottom of the flip chip is often filled with bottom filler to protect it. In order to increase the bonding strength between the bottom filler and the chip surface protective layer, plasma bombardment of the organic surface is often used to improve the roughness of the organic surface to enhance the bonding strength of the filler. If silicon nitride and other materials are used as a protective layer, the plasma bombardment has a poor effect on the roughness of the surface, resulting in poor bonding strength and poor welding effect. In addition, when soldering tin balls to tin balls, the welding strength is low, and cold soldering is prone to occur. In addition, the tin material melts and flows when heated, and its fluidity is good, so it is easy to flow on the sides of the soldering point and cause bridging problems. Summary of the invention

[0004] The objectives of the present invention include, for example, providing a bump package structure and a method for preparing the bump package structure, which can improve the welding effect and prevent the solder flank flow, thereby effectively alleviating the occurrence of bridging phenomenon.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a bump package structure, comprising:

[0007] A chip having a bonding pad disposed on one side;

[0008] A first protective layer is provided on one side of the chip, the first protective layer covers the outside of the bonding pad, and a first opening penetrating to the bonding pad is provided on the first protective layer;

[0009] A second protective layer is disposed on the first protective layer, wherein the second protective layer is provided with a second opening penetrating to the first opening;

[0010] a third protective layer disposed on the second protective layer, wherein the third protective layer is provided with a third opening penetrating to the second opening;

[0011] a conductive metal layer located in the first opening and disposed on the pad;

[0012] a conductive bump located in the second opening and disposed on the conductive metal layer;

[0013] and, a welding cap located in the third opening and disposed on the conductive bump;

[0014] The second protection layer is coated around the conductive bump, the welding cap protrudes from the third protection layer, and the edge of the third opening is spaced apart from the welding cap.

[0015] In an optional embodiment, the conductive metal layer includes an adhesive metal layer, a barrier metal layer and a wetting metal layer, the adhesive metal layer is arranged on the solder pad and partially covers the first protective layer, the barrier metal layer is arranged on the adhesive metal layer, the wetting metal layer is arranged on the barrier metal layer, and the conductive bump is arranged on the wetting metal layer.

[0016] In an optional embodiment, a first metal diffusion prevention layer is further provided between the welding cap and the conductive bump, and the first metal diffusion prevention layer is used to prevent atomic diffusion between the welding cap and the conductive bump.

[0017] In an optional embodiment, a first metal adhesion layer is further disposed between the first metal anti-expansion layer and the conductive bump, and the first metal adhesion layer is used to enhance the bonding force between the first metal anti-expansion layer and the conductive bump.

[0018] In an optional embodiment, the width of the welding cap is greater than the width of the conductive bump, so that the welding cap covers the conductive bump and partially covers the second protective layer.

[0019] In an optional embodiment, a plurality of first grooves are provided on the second protective layer, the plurality of first grooves are distributed at least on both sides of the conductive bump and are arranged close to the conductive bump, and the welding cap covers the plurality of first grooves and extends into the first grooves.

[0020] In an optional embodiment, a buffer layer is further disposed in each of the first grooves, and a thickness of the buffer layer is smaller than a depth of the first groove.

[0021] In an optional embodiment, a plurality of second grooves are further provided on the second protective layer, the plurality of second grooves are distributed at least on two sides of the conductive bump and are located in the third opening, and each of the second grooves is spaced apart from the welding cap.

[0022] In an optional embodiment, a second metal anti-expansion layer is disposed in each of the second grooves, and the second metal anti-expansion layer covers the bottom wall and the side walls of the second groove and extends to around the opening of the second groove.

[0023] In an optional embodiment, a second metal adhesion layer is further disposed in each of the second grooves, and the second metal adhesion layer is disposed between the second metal anti-expansion layer and the second protective layer.

[0024] In a second aspect, the present invention provides a method for preparing a bump package structure, which is used to prepare the bump package structure as described in any one of the above embodiments, and the preparation method comprises:

[0025] Providing a chip with a bonding pad;

[0026] Disposing a first protective layer covering the outside of the bonding pad on one side of the chip;

[0027] forming a first opening on the first protective layer that passes through the welding pad;

[0028] Disposing a second protective layer on the first protective layer;

[0029] forming a second opening on the second protective layer that passes through the first opening;

[0030] forming a conductive metal layer in the first opening, wherein the conductive metal layer is disposed on the pad;

[0031] forming a conductive bump in the second opening, wherein the conductive bump is disposed on the conductive metal layer;

[0032] Disposing a third protective layer on the second protective layer;

[0033] forming a third opening on the third protection layer and penetrating to the conductive bump;

[0034] forming a welding cap in the third opening, wherein the welding cap is disposed on the conductive bump;

[0035] The second protection layer is coated around the conductive bump, the welding cap protrudes from the third protection layer, and the edge of the third opening is spaced apart from the welding cap.

[0036] The beneficial effects of the embodiments of the present invention include, for example:

[0037] The bump package structure provided by the embodiment of the present invention, by setting the conductive bump in the second opening, allows the second protective layer to be coated around the conductive bump, plays a protective role on the conductive bump, can avoid the conductive bump from undercutting during etching, effectively ensures the connection and conductive function of the conductive bump, and avoids the problem of copper column bump falling. At the same time, a third protective layer is additionally arranged on the second protective layer, and a third opening is formed on the third protective layer, and the edge of the third opening is arranged at intervals from the welding cap, so that the welding cap is accommodated in the third opening, and the welding cap protrudes from the third protective layer. During actual welding, by setting the third opening, the solder ball can play a role in strengthening the strength of the welding structure during welding, and at the same time, it can prevent the solder from flowing sideways and avoid bridging problems. At the same time, after the electroplating tin layer, when welding on the substrate, when the pad is a circuit, the third protective layer can limit the flow of solder, and during the reflow process, when the bottom filling glue is performed after the welding process on the substrate, the bottom glue layer can be better filled into the third opening by capillary action, thereby improving the welding effect. When the pad on the substrate is a solder ball structure, the solder ball and the tin cap are welded to make the solder mutually melted, which can make the solder accommodation space larger, and the third opening can allow the solder to enter, ensuring the welding accuracy. Compared with the prior art, the bump package structure provided by the present invention can improve the welding effect, prevent the solder from flowing sideways, and effectively slow down the occurrence of bridging phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 A schematic diagram of a bump package structure provided by a first embodiment of the present invention;

[0040] Figure 2 for Figure 1 A partial enlarged schematic diagram of middle Ⅱ;

[0041] Figure 3 and Figure 4 A schematic diagram of the connection structure between the bump package structure and different substrates provided in the first embodiment of the present invention;

[0042] Figure 5 A schematic diagram of a bump package structure provided by a second embodiment of the present invention;

[0043] Figure 6 for Figure 5 A partial enlarged schematic diagram of middle VI;

[0044] Figure 7 A schematic diagram of a bump package structure provided by a third embodiment of the present invention;

[0045] Figure 8 for Figure 7 A partial enlarged schematic diagram of Figure Ⅷ;

[0046] Fig. 9 A schematic diagram of a bump package structure provided by a fourth embodiment of the present invention;

[0047] Fig.10 for Fig. 9 A partial enlarged schematic diagram of middle Ⅹ;

[0048] Figures 11 to 18 A process flow chart of a method for preparing a bump package structure provided in accordance with a fifth embodiment of the present invention.

[0049] Icon: 100-bump package structure; 110-chip; 111-solder pad; 120-first protective layer; 121-first opening; 130-second protective layer; 131-second opening; 133-first groove; 135-buffer layer; 137-second groove; 138-second metal anti-expansion layer; 139-second metal adhesion layer; 140-third protective layer; 141-third opening; 150-conductive metal layer; 151-adhesive metal layer; 153-barrier metal layer; 155-wetting metal layer; 160-conductive bump; 170-solder cap; 171-first metal adhesion layer; 173-first metal anti-expansion layer; 200-substrate; 210-protective adhesive layer. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0053] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0054] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0055] As disclosed in the background technology, in the prior art, for flip-chip packaging structures, copper pillar bumps are usually used to make electrical connections between the chip and the substrate. The existing copper pillar bumps are usually bare bump structures, that is, the copper pillar bumps are arranged on the front of the chip and protrude from the chip to be exposed, and the tin caps on the copper pillar bumps are used to weld with the corresponding pads on the substrate. When making the metal layer (UBM) of the copper pillar bump, it is necessary to etch and remove the excess metal layer, and because the material of the protective layer is very easy to absorb water, the etching liquid will remain on the side wall of the metal layer. After the copper pillar bump is formed, the bottom of the copper pillar bump is excessively corroded and an undercut opening is formed, which causes the copper pillar bump to easily fall off during reliability testing, affecting the quality of the device.

[0056] In addition, as the spacing between copper pillar bumps becomes smaller and smaller, it is often necessary to use bottom filling glue to fill and protect the bottom of the flip chip. However, the bonding effect between the filling glue and the protective layer is not good. In order to increase the bonding strength between the bottom filling glue and the chip surface protective layer, it is often necessary to use plasma bombardment on the organic surface to improve the surface roughness of the protective layer to enhance the bonding strength of the filling glue. However, if silicon nitride and other materials are used as protective layers, the plasma bombardment has a poor effect on the roughness of its surface, and the improvement of the bonding strength is poor, resulting in the bonding strength being affected and the welding effect being poor. In addition, when the pads on the substrate are tin balls, the tin balls on the chip and the tin balls on the substrate are welded in position, and the welding strength is low, which is prone to cold soldering. In addition, after being heated, the tin material tends to flow on the flanks of the welding point, thereby causing bridging problems between adjacent solder joints.

[0057] In order to solve the above problems, the present invention provides a novel bump package structure and a method for preparing the bump package structure. It should be noted that the features in the embodiments of the present invention can be combined with each other without conflict.

[0058] First embodiment

[0059] See also Figure 1 and Figure 2The present embodiment provides a bump package structure 100, which can improve the welding effect, prevent the solder flank from flowing, and effectively slow down the occurrence of bridging phenomenon. It can also effectively prevent the undercut phenomenon and avoid the bump from falling off.

[0060] The bump package structure 100 provided in this embodiment includes a chip 110, a first protective layer 120, a second protective layer 130, a third protective layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170. A solder pad 111 is arranged on one side of the chip 110. The first protective layer 120 is arranged on the side of the chip 110 having the solder pad 111. The first protective layer 120 is coated outside the solder pad 111, and a first opening 121 penetrating to the solder pad 111 is arranged on the first protective layer 120. The second protective layer 130 is arranged on the first protective layer 120, and a second opening 131 penetrating to the first opening 121 is arranged on the second protective layer 130. The third protective layer 140 is arranged on the second protective layer 130, and a third opening 141 penetrating to the second opening 131 is arranged on the third protective layer 140. The conductive metal layer 150 is located in the first opening 121 and is arranged on the solder pad 111, the conductive bump 160 is located in the second opening 131 and is arranged on the conductive metal layer 150, and the solder cap 170 is located in the third opening 141 and is arranged on the conductive bump 160, wherein the second protective layer 130 is wrapped around the conductive bump 160, the solder cap 170 protrudes from the third protective layer 140, and the edge of the third opening 141 is spaced apart from the solder cap 170.

[0061] In this embodiment, the second protective layer 130 preferably uses a photoresist material and is coated around the conductive bump 160, which can completely cover the bottom of the conductive bump 160, thereby avoiding excessive etching of the bottom of the conductive bump 160 by the etching residual liquid, and avoiding the undercut phenomenon that affects the structural strength of the conductive bump 160. In addition, during actual welding, by setting the third opening 141, the solder ball can play a role in strengthening the welding structure strength during welding, and at the same time, it can prevent the solder from flowing sideways to avoid bridging problems. At the same time, after the electroplating tin layer, when welding the substrate 200, when the pad is a circuit, the third protective layer 140 can limit the flow of solder, and during the reflow process, when the bottom filling glue is performed after the welding process on the substrate 200, the bottom glue layer can be better filled into the third opening 141 through capillary action, thereby improving the welding effect. When the solder pad on the substrate 200 is a solder ball structure, the solder ball and the tin cap are welded to make the solder melt together, which can make the solder accommodation space larger, and the third opening 141 can allow the solder to enter, ensuring the welding accuracy.

[0062] It should be noted that, in the present embodiment, the first protective layer 120 may be polyimide, which can protect the pad 111, and the first protective layer 120 may also be a material such as silicon nitride. The second protective layer 130 and the third protective layer 140 may be a photoresist material or a protective glue material, such as a polyester derivative, etc., and the specific materials thereof may refer to existing photoresists. Of course, since the first opening 121, the second opening 131 and the third opening 141 are formed separately here, the first protective layer 120, the second protective layer 130 and the third protective layer 140 may also be made of three materials with different material properties to avoid over-etching.

[0063] During actual preparation, the first protective layer 120 can be formed first, and the first opening 121 can be formed after etching. Then, the second protective layer 130 is covered, and the second opening 131 is etched again. Then, a conductive metal layer 150 and a conductive bump 160 are formed in the first opening 121 and the second opening 131 respectively. Then, the third protective layer 140 is covered, and the third opening 141 is formed after etching again. Then, the solder is covered, and a solder cap 170 is formed in the third opening 141 after reflow.

[0064] In this embodiment, the conductive metal layer 150 includes an adhesive metal layer 151, a barrier metal layer 153 and a wetting metal layer 155. The adhesive metal layer 151 is disposed on the pad 111 and partially covers the first protective layer 120. The barrier metal layer 153 is disposed on the adhesive metal layer 151, the wetting metal layer 155 is disposed on the barrier metal layer 153, and the conductive bump 160 is disposed on the wetting metal layer 155. Specifically, the adhesive metal layer 151 covers the entire first opening 121, with the center portion thereof covering the pad 111 and the edge portion thereof covering the first protective layer 120. By providing the adhesive metal layer 151, the bonding force between the barrier metal layer 153 and the pad 111 can be improved. The adhesive metal layer 151 can be a titanium layer with a thickness between 4 μm and 6 μm. The titanium layer has extremely high metal bonding performance. The barrier metal layer 153 may be made of nickel, vanadium, chromium and other materials, and the thickness of the barrier metal layer 153 is between 4μm and 6μm, and the barrier metal layer 153 can play the role of electrical connection and diffusion blocking. The wetting metal layer 155 may be made of a copper layer, and the thickness of the copper layer 155 is between 2μm and 4μm, and the wetting metal layer 155 plays the role of transitional wetting of the upper conductive bump 160, thereby improving the bonding force between the conductive bump 160 and the barrier metal layer 153. In this embodiment, the bonding metal layer 151, the barrier metal layer 153 and the wetting metal layer 155 all have good conductive effects, which can ensure effective electrical connection, so that the conductive bump 160 and the pad 111 can be electrically connected.

[0065] In this embodiment, a first metal anti-expansion layer 173 is further provided between the welding cap 170 and the conductive bump 160, and the first metal anti-expansion layer 173 is used to prevent atomic diffusion between the welding cap 170 and the conductive bump 160. Specifically, the welding cap 170 is a tin cap, the conductive bump 160 is a copper column, and the first metal anti-expansion layer 173 can be an alloy of electroplated nickel and vanadium, with a thickness between 2μm and 4μm. The first metal anti-expansion layer 173 can prevent the tin atoms in the welding cap 170 at the top from diffusing to the copper column below.

[0066] In this embodiment, a first metal adhesion layer 171 is further provided between the first metal anti-expansion layer 173 and the conductive bump 160, and the first metal adhesion layer 171 is used to improve the bonding force between the first metal anti-expansion layer 173 and the conductive bump 160. Specifically, the first metal adhesion layer 171 may also be a titanium layer with a thickness between 4 μm and 6 μm, and the titanium layer has extremely high metal bonding performance, which can improve the bonding force of adjacent layers.

[0067] In this embodiment, the width of the welding cap 170 is greater than the width of the conductive bump 160, so that the welding cap 170 covers the conductive bump 160 and partially covers the second protective layer 130. Specifically, the bottom cross-sectional size of the welding cap 170 is greater than the cross-sectional size of the conductive bump 160, so that the welding cap 170 can completely cover the top of the conductive bump 160 and extend outward. Since the conductive bump 160 is embedded in the second protective layer 130, the second protective layer 130 can play a bearing role on the edge of the welding cap 170. On the one hand, the welding cap 170 can be made larger, the volume of solder during welding can be increased, and the welding effect can be ensured. On the other hand, due to the blocking effect of the second protective layer 130, the welding cap 170 will not crawl sideways to the side wall of the conductive bump 160, and the atomic diffusion between the welding cap 170 and the side wall of the conductive bump 160 is avoided, thereby ensuring the electrical connection effect.

[0068] It should be noted that in this embodiment, the size of the third opening 141 is larger than the size of the welding cap 170, so that the edge of the welding cap 170 is spaced apart from the third protective layer 140, and a welding gap is formed between the two, and the welding gap can accommodate solder and bottom filling glue to improve the welding effect between the chip 110 and the substrate 200. Figure 3 When the pad on the substrate 200 is a circuit, the solder cap 170 is directly soldered to the pad on the substrate 200. At this time, a protective adhesive layer 210 needs to be applied to the bottom of the chip 110 to protect the soldering structure at the bottom of the chip 110. Here, the protective adhesive layer 210 covers the surrounding of the soldering point and can flow into the soldering gap of the third opening 141, thereby improving the bonding effect and objectively improving the soldering effect between the chip 110 and the substrate 200. Figure 4When the pad on the substrate 200 is a solder ball, the solder cap 170 is welded to the solder ball. At this time, the solder is mutually melted and the volume of the solder is large, so it is easy to flow on the side of the soldering point. At this time, the solder gap also plays a role in accommodating the solder, preventing the solder from spreading to the surrounding area and avoiding the occurrence of bridging. In addition, the solder is accommodated in the solder gap, which increases the soldering area, objectively improves the strength of the soldering structure, and improves the welding effect between the chip 110 and the substrate 200.

[0069] In summary, the present embodiment provides a bump package structure 100, which provides a conductive bump 160 in the second opening 131, so that the second protective layer 130 can be wrapped around the conductive bump 160, thereby protecting the conductive bump 160, and avoiding the undercut phenomenon of the conductive bump 160 during etching, effectively ensuring the connection and conductive function of the conductive bump 160, and avoiding the problem of the copper column bump falling. At the same time, a third protective layer 140 is additionally provided on the second protective layer 130, and a third opening 141 is formed on the third protective layer 140, and the edge of the third opening 141 is spaced from the welding cap 170, so that the welding cap 170 is accommodated in the third opening 141, and the welding cap 170 protrudes from the third protective layer 140. During actual welding, by providing the third opening 141, the strength of the welding structure can be enhanced during solder ball welding, and at the same time, the solder flank flow can be prevented to avoid bridging problems. At the same time, after the electroplating tin layer, when the substrate 200 is welded, when the pad is a circuit, the third protective layer 140 can limit the flow of solder, and during the reflow process, when the bottom filling glue is performed after the welding process on the substrate 200, the bottom glue layer can be better filled into the third opening 141 through capillary action, thereby improving the welding effect. And when the pad on the substrate 200 is a solder ball structure, the welding between the solder ball and the tin cap allows the solder to melt each other, which can make the solder accommodation space larger, and the third opening 141 allows the solder to enter, ensuring the welding accuracy.

[0070] Second embodiment

[0071] See also Figure 5 and Figure 6 This embodiment provides a bump package structure 100, whose basic structure, principle and technical effects are the same as those of the first embodiment. For the sake of brief description, for parts not mentioned in this embodiment, reference may be made to the corresponding contents in the first embodiment.

[0072] In this embodiment, the bump package structure 100 includes a chip 110, a first protective layer 120, a second protective layer 130, a third protective layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170, a solder pad 111 is arranged on one side of the chip 110, the first protective layer 120 is arranged on the side of the chip 110 having the solder pad 111, the first protective layer 120 is covered outside the solder pad 111, and a first opening 121 is arranged on the first protective layer 120, and a second opening 131 is arranged on the second protective layer 130, and a third protective layer 140 is arranged on the second protective layer 130, and a third opening 141 is arranged on the third protective layer 140, which passes through the second opening 131. The conductive metal layer 150 is located in the first opening 121 and is arranged on the solder pad 111, the conductive bump 160 is located in the second opening 131 and is arranged on the conductive metal layer 150, and the solder cap 170 is located in the third opening 141 and is arranged on the conductive bump 160, wherein the second protective layer 130 is wrapped around the conductive bump 160, the solder cap 170 protrudes from the third protective layer 140, and the edge of the third opening 141 is spaced apart from the solder cap 170.

[0073] In this embodiment, a plurality of first grooves 133 are provided on the second protection layer 130, and the plurality of first grooves 133 are at least distributed on both sides of the conductive bump 160 and are provided close to the conductive bump 160, and the welding cap 170 covers the plurality of first grooves 133 and extends into the first grooves 133. Specifically, the plurality of first grooves 133 are all formed by etching downward, and when the welding cap 170 is formed, the solder will extend into the first groove 133, thereby improving the bonding strength between the welding cap 170 and the conductive bump 160, thereby preventing the flanks of the welding cap 170 from cracking after the reliability test.

[0074] In this embodiment, a first metal anti-expansion layer 173 and a first metal adhesion layer 171 are further provided between the welding cap 170 and the conductive bump 160, and the first metal anti-expansion layer 173 and the first metal adhesion layer 171 extend into the first groove 133. Specifically, the size of the welding cap 170 is larger than the size of the conductive bump 160, so that the side wings of the welding cap 170 can extend around and cover a plurality of first grooves 133, and the plurality of first grooves 133 can be arranged around the conductive bump 160.

[0075] The bump package structure 100 provided in this embodiment adds a first groove 133 on the second protective layer 130, and the solder cap 170 covers the first groove 133, so that the solder can enter the first groove 133, which greatly improves the bonding force between the solder cap 170 and the conductive bump 160 and can effectively prevent the side wing of the solder cap 170 from cracking.

[0076] Third embodiment

[0077] See also Figure 7 and Figure 8 This embodiment provides a bump package structure 100, whose basic structure, principle and technical effects are the same as those of the first embodiment or the second embodiment. For the sake of brief description, parts not mentioned in this embodiment may refer to the corresponding contents in the first embodiment or the second embodiment.

[0078] In this embodiment, the bump package structure 100 includes a chip 110, a first protective layer 120, a second protective layer 130, a third protective layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170, a solder pad 111 is arranged on one side of the chip 110, the first protective layer 120 is arranged on the side of the chip 110 having the solder pad 111, the first protective layer 120 is covered outside the solder pad 111, and a first opening 121 is arranged on the first protective layer 120, and a second opening 131 is arranged on the second protective layer 130, and a third protective layer 140 is arranged on the second protective layer 130, and a third opening 141 is arranged on the third protective layer 140, which passes through the second opening 131. The conductive metal layer 150 is located in the first opening 121 and is disposed on the solder pad 111. The conductive bump 160 is located in the second opening 131 and is disposed on the conductive metal layer 150. The solder cap 170 is located in the third opening 141 and is disposed on the conductive bump 160. The second protective layer 130 is coated around the conductive bump 160. The solder cap 170 protrudes from the third protective layer 140, and the edge of the third opening 141 is spaced from the solder cap 170. A plurality of first grooves 133 are disposed on the second protective layer 130. The plurality of first grooves 133 are at least distributed on both sides of the conductive bump 160 and are disposed close to the conductive bump 160. The solder cap 170 covers the plurality of first grooves 133 and extends into the first grooves 133.

[0079] In this embodiment, a buffer layer 135 is further provided in each first groove 133, and the thickness of the buffer layer 135 is less than the depth of the first groove 133. Specifically, by providing the buffer layer 135 in the first groove 133, the welding stress of the side wall welding can be relieved, thereby preventing the side wall of the back welding cap 170 from cracking. Among them, the thickness of the buffer layer 135 is less than half of the depth of the first groove 133, so that enough solder can enter the first groove 133.

[0080] It should be noted that the material of the buffer layer 135 here can be a polymer composite material such as epoxy resin, polystyrene, etc., which can have a good buffering effect and prevent the welding cap 170 from cracking.

[0081] Fourth embodiment

[0082] See also Fig. 9 and Fig.10 This embodiment provides a bump package structure 100, whose basic structure, principle and technical effects are the same as those of the first embodiment or the second embodiment. For the sake of brief description, parts not mentioned in this embodiment may refer to the corresponding contents in the first embodiment or the second embodiment.

[0083] In this embodiment, the bump package structure 100 includes a chip 110, a first protective layer 120, a second protective layer 130, a third protective layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170, a solder pad 111 is arranged on one side of the chip 110, the first protective layer 120 is arranged on the side of the chip 110 having the solder pad 111, the first protective layer 120 is covered outside the solder pad 111, and a first opening 121 is arranged on the first protective layer 120, and a second opening 131 is arranged on the second protective layer 130, and a third protective layer 140 is arranged on the second protective layer 130, and a third opening 141 is arranged on the third protective layer 140, which passes through the second opening 131. The conductive metal layer 150 is located in the first opening 121 and is disposed on the solder pad 111. The conductive bump 160 is located in the second opening 131 and is disposed on the conductive metal layer 150. The solder cap 170 is located in the third opening 141 and is disposed on the conductive bump 160. The second protective layer 130 is wrapped around the conductive bump 160. The solder cap 170 protrudes from the third protective layer 140, and the edge of the third opening 141 is spaced from the solder cap 170. A plurality of first grooves 133 are disposed on the second protective layer 130. The plurality of first grooves 133 are at least distributed on both sides of the conductive bump 160 and are disposed close to the conductive bump 160. The solder cap 170 covers the plurality of first grooves 133 and extends into the first grooves 133.

[0084] In this embodiment, a plurality of second grooves 137 are further provided on the second protective layer 130, and the plurality of second grooves 137 are distributed at least on both sides of the conductive bump 160 and are located in the third opening 141, and each second groove 137 is spaced apart from the welding cap 170. Specifically, the second groove 137 is located in the third opening 141 between the welding cap 170 and the third protective layer 140, that is, in the welding gap between the welding cap 170 and the third protective layer 140, and each second groove 137 is also etched downward, and its depth is less than the depth of the first groove 133. By providing the second groove 137, the spatial range of the welding gap can be expanded, and more solder or adhesive layer can be accommodated during welding, further improving the welding effect.

[0085] In this embodiment, a second metal anti-expansion layer 138 is disposed in each second groove 137, and the second metal anti-expansion layer 138 covers the bottom wall and the side wall of the second groove 137 and extends around the opening of the second groove 137. By providing the second metal anti-expansion layer 138, the solder can be blocked to prevent the solder from flowing further downward.

[0086] In this embodiment, a second metal adhesion layer 139 is further disposed in each second groove 137, and the second metal adhesion layer 139 is disposed between the second metal anti-expansion layer 138 and the second protective layer 130. Specifically, the second metal adhesion layer 139 can enhance the bonding force between the second protective layer 130 and the second metal anti-expansion layer 138 to prevent the second metal anti-expansion layer 138 from falling off.

[0087] It should be noted that, in this embodiment, the second metal anti-expansion layer 138 and the second metal adhesion layer 139 both cover the bottom wall, the side wall and the periphery of the opening of the second groove 137. In other preferred embodiments of the present invention, the second metal anti-expansion layer 138 and the second metal adhesion layer 139 may also diffuse to the entire surface of the second protective layer 130, or directly diffuse to the welding cap 170 and be integrated with the first metal anti-expansion layer 173 and the first metal adhesion layer 171, and the specific configuration is not specifically limited herein.

[0088] The bump package structure 100 provided in this embodiment can accommodate solder when the chip 110 is welded by additionally setting a second groove 137 on the second protective layer 130, thereby improving the welding bonding force between the solder ball on the substrate 200 and the welding cap 170 on the chip 110, and improving the welding accuracy between the solder ball and the welding cap 170 or the circuit pad and the welding cap 170. At the same time, by setting the second groove 137, the stress of the welding structure can be released, thereby further relieving the welding stress and preventing local force concentration from causing hidden cracks. At the same time, the second metal anti-expansion layer 138 and the second metal adhesion layer 139 are set through the hub cover, which can further prevent the tin atoms on the welding cap 170 from diffusing downward to the conductive bump 160, thereby improving the welding performance.

[0089] Fifth embodiment

[0090] This embodiment provides a method for preparing a bump package structure 100, which is used to prepare the bump package structure 100 provided in the first embodiment, the second embodiment, the third embodiment or the fourth embodiment. The preparation method provided in this embodiment includes the following steps:

[0091] S1: Provide a chip 110 with a bonding pad 111.

[0092] Specifically, a chip 110 with a bonding pad 111 is provided, wherein the bonding pad 111 may be an aluminum bonding pad 111 , and the chip 110 may be prepared in advance.

[0093] S2: a first protection layer 120 is disposed on one side of the chip 110 and covers the outside of the bonding pad 111 .

[0094] Specifically, see Fig.11 On the side of the chip 110 with the pad 111, a liquid protective material (such as polyimide) is evenly coated on the surface of the newly-made jaw by a coating machine in a spin coating manner, and then soft-baked on a hot plate to form a film, thereby forming a first protective layer 120.

[0095] S3 : forming a first opening 121 on the first protection layer 120 , which passes through the pad 111 .

[0096] Specifically, see Fig.12 , through an exposure machine, a photomask is used in a proximity method to cover the position of the predetermined opening of the first protective layer 120 without exposing it to light, and a developer is used again by spraying the developer to remove the unexposed area, revealing the position of the opening of the aluminum pad 111, thereby forming a first opening 121, and then an oven is used to heat the first protective layer 120 to accelerate the curing to a fully matured stable state, and a plasma descum is used again to remove organic pollutants on the surface of the first protective layer 120 or residues in the opening, completing the operation of revealing the aluminum pad 111.

[0097] S4 : disposing the second protection layer 130 on the first protection layer 120 .

[0098] Specifically, see Fig.13 After photoresist / protective glue is coated on the surface of the first protective layer 120, the second protective layer 130 is formed.

[0099] S5 : forming a second opening 131 on the second protection layer 130 that passes through the first opening 121 .

[0100] Specifically, see Fig.14 An aluminum pad opening is formed on the second protection layer 130 by using a photolithography process, thereby forming a second opening 131 .

[0101] S6 : forming a conductive metal layer 150 in the first opening 121 , and the conductive metal layer 150 is disposed on the pad 111 .

[0102] Specifically, see Fig.15, a conductive metal layer 150 is formed in the first opening 121 by means of an electroplating process. In this embodiment, the conductive metal layer 150 is multi-layered, and the specific process is as follows: First, a layer of titanium metal with a thickness of 4-6μm is electroplated in the first opening 121 to form an adhesive metal layer 151. Since the titanium layer has extremely high metal bonding properties, the bonding strength of the subsequent barrier metal layer 153 is guaranteed, and since the second protective layer 130 is used to cover the surrounding area, there is no need to perform an etching process to etch away the excess metal layer, thereby avoiding the problem of over-etching. After the adhesive metal layer 151 is formed, a layer of metal is electroplated on the surface of the adhesive metal layer 151 again to form a barrier metal layer 153. The barrier metal layer 153 can be made of nickel, vanadium chromium or other materials. At the same time, the thickness of the barrier metal layer 153 is between 4μm and 6μm. The barrier metal layer 153 can play the role of electrical connection and diffusion prevention. After forming the barrier metal layer 153 , the electroplating process is used again to form the wetting metal layer 155 . The wetting metal layer 155 may be a copper layer with a thickness of 2-4 μm. The wetting metal layer 155 serves to transitionally wet the upper conductive bump 160 , thereby enhancing the bonding force between the conductive bump 160 and the barrier metal layer 153 .

[0103] S7: forming a conductive bump 160 in the second opening 131 , and the conductive bump 160 is disposed on the conductive metal layer 150 .

[0104] Specifically, see Fig.16 After forming the conductive metal layer 150, the copper pillars are formed on the wet metal layer 155 by electroplating, thereby forming the conductive bumps 160, and then the excess photoresist is removed by a plasma descum to form a structure with copper pillars. Here, the second protective layer 130 formed once can be used to sequentially perform metal layer UBM sputtering and electroplating copper pillar formation after the opening, which greatly reduces the process flow.

[0105] It should be noted that, in order to facilitate the preparation of subsequent processes, the conductive bump 160 can be made flush with the second protective layer 130 .

[0106] S8 : Disposing a third protective layer 140 on the second protective layer 130 .

[0107] Specifically, see Fig.17 , photoresist / protective glue is coated on the surface of the second protective layer 130 again to form a third protective layer 140 , wherein the third protective layer 140 covers the surface of the second protective layer 130 .

[0108] S9 : forming a third opening 141 on the third protection layer 140 and penetrating to the conductive bump 160 .

[0109] Specifically, see Fig.18 , a groove is made to the surface of the copper pillar by using a photolithography process to form an opening, and then a first metal adhesion layer 171 and a first metal anti-expansion layer 173 are electroplated in the opening by using an electroplating process. The first metal adhesion layer 171 can also be a titanium layer, and the first metal anti-expansion layer 173 can be an alloy of electroplated nickel and vanadium. After the first metal anti-expansion layer 173 is formed, micro-etching is performed on the protective layer again, and then the side walls of the first metal anti-expansion layer 173 and the first metal adhesion layer 171 are leaked to form a third opening 141.

[0110] S10 : forming a solder cap 170 in the third opening 141 , and the solder cap 170 is disposed on the conductive bump 160 .

[0111] For details, please refer to Figure 1 , use electroplating process or printing process to fill solder into the third opening 141, and then complete the solder filling by controlling electroplating parameters or printing thickness, and then use plasma residual glue remover to remove excess photoresist to form a copper column with solder, and then reflow again to form a solder cap 170 to complete the process.

[0112] In this embodiment, the second protection layer 130 is coated around the conductive bump 160 , the solder cap 170 protrudes from the third protection layer 140 , and the edge of the third opening 141 is spaced apart from the solder cap 170 .

[0113] The method for preparing the bump package structure 100 provided in this embodiment, by setting the conductive bump 160 in the second opening 131, allows the second protective layer 130 to be wrapped around the conductive bump 160, thereby protecting the conductive bump 160, and preventing the conductive bump 160 from undercutting during etching, effectively ensuring the connection and conductive function of the conductive bump 160, and avoiding the problem of the copper column bump falling. At the same time, a third protective layer 140 is additionally provided on the second protective layer 130, and a third opening 141 is formed on the third protective layer 140, and the edge of the third opening 141 is spaced from the welding cap 170, so that the welding cap 170 is accommodated in the third opening 141, and the welding cap 170 protrudes from the third protective layer 140. During actual welding, by setting the third opening 141, the strength of the welding structure can be enhanced during solder ball welding, and at the same time, the solder flank flow can be prevented to avoid bridging problems. At the same time, after the electroplating tin layer, when the substrate 200 is welded, when the pad is a circuit, the third protective layer 140 can limit the flow of solder, and during the reflow process, when the bottom filling glue is performed after the welding process on the substrate 200, the bottom glue layer can be better filled into the third opening 141 through capillary action, thereby improving the welding effect. And when the pad on the substrate 200 is a solder ball structure, the welding between the solder ball and the tin cap allows the solder to melt each other, which can make the solder accommodation space larger, and the third opening 141 allows the solder to enter, ensuring the welding accuracy.

[0114] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A bump package structure, characterized in that: include: A chip having a bonding pad disposed on one side; A first protective layer is provided on one side of the chip, the first protective layer covers the outside of the bonding pad, and a first opening penetrating to the bonding pad is provided on the first protective layer; a second protective layer disposed on the first protective layer, wherein the second protective layer is provided with a second opening penetrating to the first opening; a third protective layer disposed on the second protective layer, wherein the third protective layer is provided with a third opening penetrating to the second opening; a conductive metal layer located in the first opening and disposed on the pad; a conductive bump located in the second opening and disposed on the conductive metal layer; and, a welding cap located in the third opening and disposed on the conductive bump; Wherein, the second protective layer is coated around the conductive bump, the welding cap protrudes from the third protective layer, and the edge of the third opening is spaced apart from the welding cap; The width of the welding cap is greater than the width of the conductive bump, so that the welding cap covers the conductive bump and partially covers the second protective layer; a plurality of second grooves are also provided on the second protective layer, and the plurality of second grooves are distributed at least on both sides of the conductive bump and are located in the third opening, and each second groove is spaced apart from the welding cap.

2. The bump package structure according to claim 1, characterized in that: The conductive metal layer includes an adhesive metal layer, a barrier metal layer and a wetting metal layer. The adhesive metal layer is arranged on the pad and partially covers the first protective layer. The barrier metal layer is arranged on the adhesive metal layer. The wetting metal layer is arranged on the barrier metal layer. The conductive bump is arranged on the wetting metal layer.

3. The bump package structure according to claim 1, characterized in that: A first metal diffusion prevention layer is further arranged between the welding cap and the conductive bump, and the first metal diffusion prevention layer is used to prevent atomic diffusion between the welding cap and the conductive bump.

4. The bump package structure according to claim 3, characterized in that: A first metal adhesion layer is further disposed between the first metal anti-expansion layer and the conductive bump, and the first metal adhesion layer is used to enhance the bonding force between the first metal anti-expansion layer and the conductive bump.

5. The bump package structure according to claim 1, characterized in that: A plurality of first grooves are arranged on the second protection layer, and the plurality of first grooves are distributed at least on both sides of the conductive bump and are arranged close to the conductive bump. The welding cap covers the plurality of first grooves and extends into the first grooves.

6. The bump package structure according to claim 5, characterized in that: A buffer layer is further disposed in each of the first grooves, and the thickness of the buffer layer is smaller than the depth of the first groove.

7. The bump package structure according to claim 1, characterized in that: A second metal anti-expansion layer is arranged in each of the second grooves. The second metal anti-expansion layer covers the bottom wall and the side wall of the second groove and extends to the periphery of the opening of the second groove.

8. The bump package structure according to claim 7, characterized in that: A second metal adhesion layer is also disposed in each of the second grooves, and the second metal adhesion layer is disposed between the second metal anti-expansion layer and the second protection layer.

9. A method for preparing a bump package structure, characterized in that: For preparing the bump package structure according to any one of claims 1 to 8, the preparation method comprises: Providing a chip with a bonding pad; Disposing a first protective layer covering the outside of the bonding pad on one side of the chip; forming a first opening on the first protective layer that passes through the welding pad; Disposing a second protective layer on the first protective layer; forming a second opening on the second protective layer that passes through the first opening; forming a conductive metal layer in the first opening, wherein the conductive metal layer is disposed on the pad; forming a conductive bump in the second opening, wherein the conductive bump is disposed on the conductive metal layer; Disposing a third protective layer on the second protective layer; forming a third opening on the third protection layer and penetrating to the conductive bump; forming a welding cap in the third opening, wherein the welding cap is disposed on the conductive bump; The second protection layer is coated around the conductive bump, the welding cap protrudes from the third protection layer, and the edge of the third opening is spaced apart from the welding cap.

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