CN114597136A - Bump packaging structure and preparation method thereof - Google Patents

Abstract

The embodiment of the invention provides a bump packaging structure and a preparation method thereof, relating to the technical field of semiconductor packaging. Simultaneously, behind the electrotinning layer, when welding to the base plate, when the pad is circuit or solder ball, the solder flow can be restricted to the third protective layer to among the reflow process, when welding carries out the underfill behind the base plate process, the bottom glue film can fill into the third opening through capillary better, thereby has promoted the welding effect.

Description

Bump packaging structure and preparation method thereof

Technical Field

The invention relates to the technical field of semiconductor packaging, in particular to a bump packaging structure and a preparation method of the bump packaging structure.

Background

With the rapid development of the semiconductor industry, the flip chip package structure is widely applied to the flip chip package in the semiconductor industry, and the bumps are used for electrically connecting the chip and the substrate. The bump comprises a copper column, a metal layer (UBM), a protective layer (Polyimide), and a tin Cap (Sn Cap), wherein after the UBM is manufactured, the redundant metal layer needs to be etched and removed, and the Polyimide is extremely easy to absorb water, so that etching liquid on the side wall of the UBM at the bottom of the metal column is remained, so that the bottom of the bump of the copper column is excessively corroded to form an undercut opening, and the bump chip has the problem that the bump of the copper column falls off when a reliability test is carried out.

In addition, in carrying out packaging technology to flip-chip copper post lug, flip-chip welds on the base plate, and is littleer and more along with the interval of copper post lug, often adopts underfill to fill the protection to the flip-chip bottom, in order to increase the adhesive strength of underfill and chip surface protection layer, often uses plasma bombardment organic surface, borrows this roughness that improves the organic matter surface, promotes the adhesive strength of underfill. If silicon nitride or other materials are used as the protective layer, the plasma bombardment has a poor effect on the surface roughness, which affects the bonding strength and results in poor welding effect. In addition, when the solder ball is soldered by the solder ball, the soldering strength is low, a cold solder phenomenon is easy to occur, and the solder material is heated to melt and flow, has good fluidity, is easy to flow at the side wing of the soldering point and causes a bridging problem.

Disclosure of Invention

The present invention provides a bump package and a method for manufacturing the same, which can improve the soldering effect, prevent the solder from flowing laterally, and effectively reduce the occurrence of the bridging phenomenon.

Embodiments of the invention may be implemented as follows:

in a first aspect, the present invention provides a bump package structure, including:

a chip having a pad disposed on one side thereof;

the first protective layer is arranged on one side of the chip, the first protective layer covers the welding pad, and a first opening penetrating through the welding pad is formed in the first protective layer;

the second protective layer is arranged on the first protective layer, and a second opening penetrating to the first opening is formed in the second protective layer;

a third protective layer arranged on the second protective layer, wherein a third opening penetrating to the second opening is formed in the third protective layer;

the conductive metal layer is positioned in the first opening and arranged on the welding pad;

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

and a solder cap positioned in the third opening and disposed on the conductive bump;

the second protective layer is wrapped around the conductive bump, the welding cap protrudes from the third protective layer, and the edge of the third opening and the welding cap are arranged at intervals.

In an optional embodiment, the conductive metal layer includes a bonding metal layer, a barrier metal layer, and a wetting metal layer, the bonding metal layer is disposed on the pad and partially covers the first protection layer, the barrier metal layer is disposed on the bonding metal layer, the wetting metal layer is disposed on the barrier metal layer, and the conductive bump is disposed on the wetting metal layer.

In an optional embodiment, a first metal anti-diffusion layer is further disposed between the solder cap and the conductive bump, and the first metal anti-diffusion layer is configured to block atomic diffusion between the solder cap and the conductive bump.

In an optional embodiment, a first metal adhesion layer is further disposed between the first metal anti-spreading layer and the conductive bump, and the first metal adhesion layer is used to improve a bonding force between the first metal anti-spreading layer and the conductive bump.

In an alternative embodiment, the width of the solder cap is greater than the width of the conductive bump, so that the solder cap covers the conductive bump and partially covers the second protective layer.

In an optional embodiment, a plurality of first grooves are disposed on the second protective layer, the plurality of first grooves are at least distributed on two sides of the conductive bump and disposed close to the conductive bump, and the solder cap covers the plurality of first grooves and extends into the first grooves.

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

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

In an optional embodiment, a second metal anti-expansion layer is arranged in each second groove, covers the bottom wall and the side wall of the second groove, and extends to the periphery of the hole of the second groove.

In an alternative embodiment, a second metal adhesion layer is further disposed in each second groove, and the second metal adhesion layer is disposed between the second metal anti-spreading layer and the second protection layer.

In a second aspect, the present invention provides a method for manufacturing a bump package structure, for manufacturing the bump package structure according to any one of the foregoing embodiments, the method comprising:

providing a chip with a welding pad;

arranging a first protective layer coated outside the welding pad on one side of the chip;

forming a first opening penetrating to the welding pad on the first protective layer;

disposing a second protective layer on the first protective layer;

forming a second opening penetrating to the first opening on the second protective layer;

forming a conductive metal layer in the first opening, wherein the conductive metal layer is arranged on the welding pad;

forming a conductive bump in the second opening, wherein the conductive bump is arranged on the conductive metal layer;

disposing a third protective layer on the second protective layer;

forming a third opening penetrating to the conductive bump on the third protective layer;

forming a solder cap in the third opening, the solder cap being disposed on the conductive bump;

the second protective layer is wrapped around the conductive bump, the welding cap protrudes from the third protective layer, and the edge of the third opening and the welding cap are arranged at intervals.

The beneficial effects of the embodiment of the invention include, for example:

according to the bump packaging structure provided by the embodiment of the invention, the conductive bump is arranged in the second opening, so that the second protective layer can be coated around the conductive bump, the protective effect on the conductive bump is achieved, the undercut phenomenon of the conductive bump can be avoided during etching, the connection conductive function of the conductive bump is effectively ensured, and the problem that the copper pillar bump falls off is avoided. Meanwhile, a third protective layer is additionally arranged on the second protective layer, a third opening is formed in the third protective layer, the edge of the third opening and the welding cap are arranged at intervals, the welding cap is contained in the third opening, and the welding cap protrudes out of the third protective layer. When actual welding, through setting up the third opening, can play the effect of strengthening welded structure intensity during the tin ball welding, can prevent simultaneously that the solder flank from flowing, avoids the bridging problem. Simultaneously, behind the electrotinning layer, when being the circuit to the base plate welding, the third protective layer can restrict the solder flow to in the backward flow process, when welding carries out the underfill behind the base plate process, the bottom glue film can fill into the third opening through capillary better, thereby has promoted the welding effect. And when the welding pad on the substrate is in a welding ball structure, welding between the welding ball and the tin cap enables the welding flux to be mutually fused, so that the accommodating space of the welding flux is larger, and the third opening can allow the welding flux to enter, so that the welding accuracy is guaranteed. Compared with the prior art, the bump packaging structure provided by the invention can improve the welding effect, prevent the solder side wing from flowing and effectively slow down the occurrence of the bridging phenomenon.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic view of a bump package structure according to a first embodiment of the invention;

FIG. 2 is an enlarged partial view of II in FIG. 1;

fig. 3 and fig. 4 are schematic views illustrating a connection structure between a bump package structure and different substrates according to a first embodiment of the invention;

fig. 5 is a schematic view of a bump package structure according to a second embodiment of the invention;

FIG. 6 is an enlarged partial schematic view of VI of FIG. 5;

fig. 7 is a schematic diagram of a bump package structure according to a third embodiment of the invention;

FIG. 8 is an enlarged partial view of VIII in FIG. 7;

fig. 9 is a schematic view of a bump package structure according to a fourth embodiment of the invention;

FIG. 10 is an enlarged partial view of X in FIG. 9;

fig. 11 to fig. 18 are process flow diagrams of a method for manufacturing a bump package structure according to a fifth embodiment of the invention.

Icon: 100-bump package structure; 110-chip; 111-pads; 120-a first protective layer; 121 — a first opening; 130-a second protective layer; 131-a second opening; 133-a first groove; 135-a buffer layer; 137-a second recess; 138-a second metal anti-expansion layer; 139-a second metal adhesion layer; 140-a third protective layer; 141-a third opening; 150-a conductive metal layer; 151-bonding a metal layer; 153-barrier metal layer; 155-infiltrating the metal layer; 160-conductive bumps; 170-welding a cap; 171-a first metal adhesion layer; 173-first metal anti-diffusion layer; 200-a substrate; 210-protective glue layer.

Detailed Description

In order to make the objects, 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 with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. indicate an orientation or a positional relationship based on that shown in the drawings or that the product of the present invention is used as it is, this is only for convenience of description and simplification of the description, and it does not indicate or imply that the device or the element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention.

Furthermore, the appearances of the terms "first," "second," and the like, if any, are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

As disclosed in the background, the electrical connection between the chip and the substrate is usually made by using copper pillar bumps for flip-chip package structure in the prior art. The conventional copper pillar bump is usually a bare bump structure, i.e., the copper pillar bump is disposed on the front surface of the chip and protrudes out of the chip, and is correspondingly welded to the bonding pad on the substrate through a tin cap on the copper pillar bump. When a metal layer (UBM) of the copper pillar bump is manufactured, the redundant metal layer needs to be etched and removed, and the protective layer is very easy to absorb water, so that etching liquid is left on the side wall of the metal layer, and after the copper pillar bump is formed, the bottom of the copper pillar bump is excessively corroded to form an undercut opening, so that the copper pillar bump is easy to drop when a reliability test is performed, and the quality of a device is influenced.

In addition, along with the interval of copper post lug is littleer and more, often need adopt underfill to fill the protection to flip-chip bottom, and the packing is glued not good with the bonding effect of protective layer, in order to increase underfill and the adhesive strength of chip surface protection layer, often need use plasma bombardment organic surface, borrow this to improve the roughness on protective layer surface, promotes the adhesive strength of packing. However, if a material such as silicon nitride is used as the protective layer, the plasma bombardment has a poor effect on the surface roughness, and the bonding strength is not improved, so that the bonding strength is affected and the welding effect is poor. Moreover, when the solder balls are used as the bonding pads on the substrate, the solder balls on the chip and the solder balls on the substrate are welded in an alignment manner, so that the welding strength is low, and the phenomenon of insufficient welding is easy to occur. And the solder material is easy to flow at the welding point lateral wing after being heated, thereby causing the bridging problem between the adjacent welding points.

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

First embodiment

Referring to fig. 1 and 2, the present embodiment provides a bump package structure 100, which can improve the soldering effect, prevent solder lateral flow, and effectively alleviate the occurrence of the bridging phenomenon. And can effectively prevent undercut phenomenon, avoid the lug to drop.

The bump package structure 100 provided in this embodiment includes a chip 110, a first protection layer 120, a second protection layer 130, a third protection layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170, wherein a pad 111 is disposed on one side of the chip 110, the first protection layer 120 is disposed on one side of the chip 110 having the pad 111, the first protection layer 120 is coated outside the pad 111, a first opening 121 penetrating to the pad 111 is disposed on the first protection layer 120, the second protection layer 130 is disposed on the first protection layer 120, a second opening 131 penetrating to the first opening 121 is disposed on the second protection layer 130, the third protection layer 140 is disposed on the second protection layer 130, and a third opening 141 penetrating to the second opening 131 is disposed on the third protection layer 140. The conductive metal layer 150 is located in the first opening 121 and disposed on the pad 111, the conductive bump 160 is located in the second opening 131 and disposed on the conductive metal layer 150, and the solder cap 170 is located in the third opening 141 and disposed on the conductive bump 160, wherein the second passivation layer 130 covers around the conductive bump 160, the solder cap 170 protrudes from the third passivation layer 140, and an edge of the third opening 141 and the solder cap 170 are spaced apart from each other.

In this embodiment, the second protection layer 130 is preferably made of a photoresist material and covers around the conductive bump 160, so as to completely cover the bottom of the conductive bump 160, thereby avoiding the over-etching of the etching residual liquid on the bottom of the conductive bump 160 and avoiding the undercut phenomenon from affecting the structural strength of the conductive bump 160. In addition, when in actual welding, the third opening 141 is arranged, so that the effect of enhancing the strength of the welding structure can be achieved during tin ball welding, and meanwhile, the solder side wing can be prevented from flowing, and the problem of bridging is avoided. Meanwhile, after the tin electroplating layer, when the substrate 200 is soldered, the third protective layer 140 may restrict the solder from flowing when the pad is a circuit, and during the reflow process and the soldering process after the substrate 200 is under-filled with glue, the bottom glue layer may be better filled into the third opening 141 through capillary action, thereby improving the soldering effect. And when the bonding pad on the substrate 200 is a solder ball structure, the solder balls and the solder caps are welded to each other, so that the solder can be contained in a larger space, and the third opening 141 can allow the solder to enter, thereby ensuring the welding accuracy.

In this embodiment, the first protection layer 120 may be Polyimide (Polyimide), which can protect the bonding pad 111, and the first protection layer 120 may also be made of a material such as silicon nitride. The second protection layer 130 and the third protection layer 140 may be a photoresist material or a protection material such as a polyester derivative, and the specific material thereof may refer to an existing photoresist. Of course, since the first opening 121, the second opening 131 and the third opening 141 are formed separately here, the first protection layer 120, the second protection layer 130 and the third protection layer 140 may also be made of three materials with different material characteristics, so as to avoid the over-etching phenomenon.

In actual manufacturing, the first protection layer 120 may be formed first, the first opening 121 is formed after etching the opening, the second protection layer 130 is covered, the second opening 131 is formed after etching the opening again, the conductive metal layer 150 and the conductive bump 160 are formed in the first opening 121 and the second opening 131 respectively, the third protection layer 140 is covered, the third opening 141 is formed after etching the opening again, the solder is covered, and the solder cap 170 is formed in the third opening 141 after reflowing.

In the present embodiment, the conductive metal layer 150 includes an adhesion metal layer 151, a barrier metal layer 153 and a wetting metal layer 155, the adhesion metal layer 151 is disposed on the pad 111 and partially covers the first protection layer 120, the barrier metal layer 153 is disposed on the adhesion 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 adhesion metal layer 151 covers the entire first opening 121, the center of the adhesion metal layer covers the pad 111, the edge of the adhesion metal layer covers the first passivation layer 120, and the adhesion force between the barrier metal layer 153 and the pad 111 can be improved by providing the adhesion metal layer 151, wherein the adhesion metal layer 151 may be a titanium layer, the thickness of the titanium layer is between 4 μm and 6 μm, and the titanium layer has a very high metal adhesion property. The barrier metal layer 153 may be made of nickel, vanadium, chromium, etc., and the thickness of the barrier metal layer 153 is between 4 μm and 6 μm, so that the barrier metal layer 153 can perform the functions of electrical connection and diffusion barrier. The wetting metal layer 155 may be a copper layer with a thickness of 2 μm to 4 μm, and the wetting metal layer 155 plays a role of wetting the upper conductive bump 160, so as to improve the bonding force between the conductive bump 160 and the barrier metal layer 153. In the embodiment, the adhesion metal layer 151, the barrier metal layer 153, and the wetting metal layer 155 all have a good conductive effect, and can ensure effective electrical connection, so that the conductive bump 160 and the pad 111 can be electrically connected.

In the present embodiment, a first metal anti-diffusion layer 173 is further disposed between the solder cap 170 and the conductive bump 160, and the first metal anti-diffusion layer 173 is used for blocking atomic diffusion between the solder cap 170 and the conductive bump 160. Specifically, the solder caps 170 are tin caps, the conductive bumps 160 are copper pillars, the first metal anti-expansion layer 173 may be an alloy of electroplated nickel and vanadium, and has a thickness of 2 μm to 4 μm, and the first metal anti-expansion layer 173 can prevent tin atoms in the top solder caps 170 from diffusing to the underlying copper pillars.

In this embodiment, a first metal adhesion layer 171 is further disposed between the first metal anti-spreading 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-spreading layer 173 and the conductive bump 160. Specifically, the first metal adhesion layer 171 may also be a titanium layer, which has a thickness of 4 μm to 6 μm and has an extremely high metal adhesion property, so as to improve the bonding force of adjacent layers.

In the present embodiment, the width of the solder cap 170 is greater than the width of the conductive bump 160, so that the solder cap 170 covers the conductive bump 160 and partially covers the second protection layer 130. Specifically, the bottom cross-sectional dimension of the solder cap 170 is larger than the cross-sectional dimension of the conductive bump 160, such that the solder cap 170 can completely cover the top of the conductive bump 160 and extend outward. Because here electrically conductive lug 160 inlays and establishes in second protective layer 130, second protective layer 130 can play the bearing effect to welding cap 170 edge, can make welding cap 170 do bigger on the one hand, promote the solder volume when welding, guarantee the welding effect, on the other hand is because the effect of blockking of second protective layer 130 for welding cap 170 can not side climb to the lateral wall of electrically conductive lug 160, the atomic diffusion between the lateral wall of welding cap 170 and electrically conductive lug 160 has also been avoided, the electric connection effect has been guaranteed.

It should be noted that, in this embodiment, the size of the third opening 141 is larger than that of the solder cap 170, so that the edge of the solder cap 170 and the third protective layer 140 are arranged at an interval, and a solder gap is formed therebetween, and the solder gap can accommodate solder and also accommodate underfill, so as to improve the soldering effect between the chip 110 and the substrate 200. Specifically, referring to fig. 3, when the pad on the substrate 200 is a circuit, that is, the welding cap 170 is directly welded to the pad on the substrate 200, at this time, the protective adhesive layer 210 needs to be applied to the bottom of the chip 110 to protect the welding structure at the bottom of the chip 110, where the protective adhesive layer 210 covers around the welding point and can flow into the welding gap of the third opening 141, so as to improve the adhesion effect and objectively improve the welding effect between the chip 110 and the substrate 200. Referring to fig. 4, when the solder pads on the substrate 200 are solder balls, the solder caps 170 are soldered to the solder balls in an aligned manner, and the solder melts and flows easily at the side wings of the solder joints, and the solder gaps also serve to contain the solder, thereby preventing the solder from being diffused to the periphery to a large extent and avoiding the occurrence of a bridging phenomenon. Moreover, the solder is accommodated in the welding gap, so that the welding area of the solder is increased, the strength of the welding structure is objectively increased, and the welding effect between the chip 110 and the substrate 200 is improved.

In summary, the present embodiment provides a bump package structure 100, in which the conductive bump 160 is disposed in the second opening 131, so that the second protection layer 130 can be wrapped around the conductive bump 160, thereby protecting the conductive bump 160, avoiding the conductive bump 160 from undercutting during etching, effectively ensuring the conductive connection function of the conductive bump 160, and avoiding the problem of the copper pillar bump falling. Meanwhile, a third passivation layer 140 is additionally disposed on the second passivation layer 130, a third opening 141 is formed on the third passivation layer 140, and an edge of the third opening 141 and the welding cap 170 are disposed at an interval, so that the welding cap 170 is accommodated in the third opening 141 and the welding cap 170 protrudes from the third passivation layer 140. In the actual welding process, the third opening 141 is arranged, so that the effect of reinforcing the strength of the welding structure can be achieved in the tin ball welding process, the solder side wing can be prevented from flowing, and the bridging problem is avoided. Meanwhile, after the tin electroplating layer, when the substrate 200 is soldered, the third protective layer 140 may restrict the solder from flowing when the pad is a circuit, and during the reflow process and the soldering process after the substrate 200 is under-filled with glue, the bottom glue layer may be better filled into the third opening 141 through capillary action, thereby improving the soldering effect. And when the bonding pad on the substrate 200 is a solder ball structure, the solder balls and the solder caps are welded to each other, so that the solder can be contained in a larger space, and the third opening 141 can allow the solder to enter, thereby ensuring the welding accuracy.

Second embodiment

Referring to fig. 5 and fig. 6, the present embodiment provides a bump package structure 100, the basic structure and principle and the generated technical effect are the same as those of the first embodiment, and for the sake of brief description, reference may be made to the corresponding contents in the first embodiment for the parts not mentioned in the present embodiment.

In this embodiment, the bump package structure 100 includes a chip 110, a first passivation layer 120, a second passivation layer 130, a third passivation layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170, wherein a pad 111 is disposed on one side of the chip 110, the first passivation layer 120 is disposed on one side of the chip 110 having the pad 111, the first passivation layer 120 covers the pad 111, a first opening 121 penetrating the pad 111 is disposed on the first passivation layer 120, the second passivation layer 130 is disposed on the first passivation layer 120, a second opening 131 penetrating the first opening 121 is disposed on the second passivation layer 130, the third passivation layer 140 is disposed on the second passivation layer 130, and a third opening 141 penetrating the second opening 131 is disposed on the third passivation layer 140. The conductive metal layer 150 is located in the first opening 121 and disposed on the pad 111, the conductive bump 160 is located in the second opening 131 and disposed on the conductive metal layer 150, and the solder cap 170 is located in the third opening 141 and disposed on the conductive bump 160, wherein the second passivation layer 130 covers around the conductive bump 160, the solder cap 170 protrudes from the third passivation layer 140, and an edge of the third opening 141 and the solder cap 170 are spaced apart from each other.

In this embodiment, the second passivation layer 130 is provided with a plurality of first grooves 133, the plurality of first grooves 133 are at least distributed on two sides of the conductive bump 160 and are disposed near the conductive bump 160, and the solder cap 170 covers the plurality of first grooves 133 and extends into the first grooves 133. Specifically, the plurality of first grooves 133 are formed by etching downward, and when the solder cap 170 is formed, solder extends into the first grooves 133, so that the bonding strength between the solder cap 170 and the conductive bump 160 is improved, and the side wing of the solder cap 170 is prevented from being cracked after the reliability test.

In this embodiment, a first metal anti-expansion layer 173 and a first metal adhesion layer 171 are further disposed between the solder 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 solder cap 170 is larger than that of the conductive bump 160, so that the side wing of the solder cap 170 can extend around and cover the plurality of first grooves 133, and the plurality of first grooves 133 can be surrounded around the conductive bump 160.

In the bump package structure 100 provided in this embodiment, the first groove 133 is additionally disposed on the second protection layer 130, and the solder cap 170 covers the first groove 133, so that the solder can enter the first groove 133, the bonding force between the solder cap 170 and the conductive bump 160 is greatly improved, and the side wing of the solder cap 170 can be effectively prevented from cracking.

Third embodiment

Referring to fig. 7 and fig. 8, the present embodiment provides a bump package structure 100, the basic structure and principle and the generated technical effect are the same as those of the first embodiment or the second embodiment, and for the sake of brief description, the corresponding contents in the first embodiment or the second embodiment may be referred to where not mentioned in part in the present embodiment.

In this embodiment, the bump package structure 100 includes a chip 110, a first passivation layer 120, a second passivation layer 130, a third passivation layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170, wherein a pad 111 is disposed on one side of the chip 110, the first passivation layer 120 is disposed on one side of the chip 110 having the pad 111, the first passivation layer 120 covers the pad 111, a first opening 121 penetrating to the pad 111 is disposed on the first passivation layer 120, the second passivation layer 130 is disposed on the first passivation layer 120, a second opening 131 penetrating to the first opening 121 is disposed on the second passivation layer 130, the third passivation layer 140 is disposed on the second passivation layer 130, and a third opening 141 penetrating to the second opening 131 is disposed on the third passivation layer 140. The conductive metal layer 150 is located in the first opening 121 and disposed on the pad 111, the conductive bump 160 is located in the second opening 131 and disposed on the conductive metal layer 150, and the solder cap 170 is located in the third opening 141 and disposed on the conductive bump 160, wherein the second passivation layer 130 covers around the conductive bump 160, the solder cap 170 protrudes from the third passivation layer 140, and an edge of the third opening 141 and the solder cap 170 are spaced apart from each other. The second passivation layer 130 is provided with a plurality of first grooves 133, the plurality of first grooves 133 are at least distributed on two sides of the conductive bump 160 and are disposed near the conductive bump 160, and the solder cap 170 covers the plurality of first grooves 133 and extends into the first grooves 133.

In this embodiment, a buffer layer 135 is further disposed in each first groove 133, and the thickness of the buffer layer 135 is smaller 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 sidewall welding can be relieved, thereby preventing the sidewall of the back welding cap 170 from being hidden apart. Wherein the thickness of the buffer layer 135 is less than half of the depth of the first groove 133, so that it is possible to secure enough solder to enter the first groove 133.

It should be noted that the material of the buffer layer 135 may be a polymer composite material such as epoxy resin, polystyrene, etc., which can achieve a good buffer effect and prevent the solder cap 170 from generating a hidden crack phenomenon.

Fourth embodiment

Referring to fig. 9 and fig. 10 in combination, the present embodiment provides a bump package structure 100, the basic structure and principle and the generated technical effect are the same as those of the first embodiment or the second embodiment, and for the sake of brief description, corresponding contents in the first embodiment or the second embodiment may be referred to where not mentioned in part in the present embodiment.

In this embodiment, the bump package structure 100 includes a chip 110, a first passivation layer 120, a second passivation layer 130, a third passivation layer 140, a conductive metal layer 150, a conductive bump 160 and a solder cap 170, wherein a pad 111 is disposed on one side of the chip 110, the first passivation layer 120 is disposed on one side of the chip 110 having the pad 111, the first passivation layer 120 covers the pad 111, a first opening 121 penetrating the pad 111 is disposed on the first passivation layer 120, the second passivation layer 130 is disposed on the first passivation layer 120, a second opening 131 penetrating the first opening 121 is disposed on the second passivation layer 130, the third passivation layer 140 is disposed on the second passivation layer 130, and a third opening 141 penetrating the second opening 131 is disposed on the third passivation layer 140. The conductive metal layer 150 is located in the first opening 121 and disposed on the pad 111, the conductive bump 160 is located in the second opening 131 and disposed on the conductive metal layer 150, and the solder cap 170 is located in the third opening 141 and disposed on the conductive bump 160, wherein the second passivation layer 130 covers around the conductive bump 160, the solder cap 170 protrudes from the third passivation layer 140, and an edge of the third opening 141 and the solder cap 170 are spaced apart from each other. The second passivation layer 130 is provided with a plurality of first grooves 133, the plurality of first grooves 133 are at least distributed on two sides of the conductive bump 160 and are disposed near the conductive bump 160, and the solder cap 170 covers the plurality of first grooves 133 and extends into the first grooves 133.

In this embodiment, the second passivation layer 130 is further provided with a plurality of second grooves 137, the plurality of second grooves 137 are at least distributed on two sides of the conductive bump 160 and located in the third opening 141, and each second groove 137 is spaced apart from the solder cap 170. Specifically, the second grooves 137 are located in the third opening 141 between the welding cap 170 and the third protection layer 140, that is, in the welding gap between the welding cap 170 and the third protection layer 140, each second groove 137 is also formed by etching downward, and the depth of each second groove 137 is smaller than that of the first groove 133, and by arranging the second grooves 137, the spatial range of the welding gap can be enlarged, and meanwhile, more solder or glue layers can be accommodated during welding, so that the welding effect is further improved.

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 to the periphery of the aperture of the second groove 137. By providing the second metal anti-spreading layer 138, the solder can be blocked, and the solder is prevented from flowing further downward.

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-spreading layer 138 and the second protection layer 130. Specifically, the second metal adhesion layer 139 can improve the bonding force between the second protection layer 130 and the second metal anti-expansion layer 138, so as to prevent the second metal anti-expansion layer 138 from falling off.

It should be noted that in this embodiment, the second metal anti-expansion layer 138 and the second metal adhesion layer 139 are covered on the bottom wall, the side wall and the periphery of the aperture of the second groove 137. In other preferred embodiments of the present invention, the second metal anti-diffusion layer 138 and the second metal adhesion layer 139 may also be diffused to the entire surface of the second protection layer 130, or directly diffused into the solder cap 170 to be integrated with the first metal anti-diffusion layer 173 and the first metal adhesion layer 171, and the specific configuration thereof is not limited herein.

In the bump package structure 100 provided by this embodiment, the second groove 137 is additionally disposed on the second protection layer 130, and when the chip 110 is soldered, solder can be accommodated, so as to improve a soldering bonding force between the solder ball on the substrate 200 and the solder cap 170 on the chip 110, and improve soldering accuracy between the solder ball and the solder cap 170 or between the circuit pad and the solder cap 170. Meanwhile, the stress of the welding structure can be released by arranging the second groove 137, so that the effect of relieving the welding stress is further achieved, and the hidden crack caused by the concentrated local stress is prevented. Meanwhile, the second metal anti-diffusion layer 138 and the second metal adhesion layer 139 are disposed through the hub cap, so that the tin atoms on the welding cap 170 can be further prevented from diffusing downward onto the conductive bump 160, thereby improving the welding performance.

Fifth embodiment

The present embodiment provides a method for manufacturing a bump package structure 100, which is used to manufacture the bump package structure 100 provided in the first, second, third, or fourth embodiments, and the method includes the following steps:

s1, a chip 110 with pads 111 is provided.

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

S2: a first passivation layer 120 is disposed on one side of the chip 110 and covers the bonding pad 111.

Specifically, referring to fig. 11, a liquid protective material (e.g., Polyimide) is uniformly coated on the surface of the newly-photographed jaw by a spin coating method on the side of the chip 110 having the bonding pad 111, and then is soft-baked and shaped to form a film via a hot plate, thereby forming the first protective layer 120.

S3: a first opening 121 is formed through the first passivation layer 120 to the pad 111.

Specifically, referring to fig. 12, the position of the predetermined opening of the first passivation layer 120 is masked by the exposure machine in a proximity method using a mask without exposure to light, the unexposed area is removed by spraying a developing solution in a developing manner again, the position of the opening of the aluminum pad 111 is leaked, so as to form the first opening 121, the first passivation layer 120 is then cured to a completely cured stable state by heating in an oven, and the organic contaminants on the surface of the first passivation layer 120 or the residues in the opening are removed by using a plasma desmear (Descum) again, so as to complete the operation of leaking the aluminum pad 111.

S4: a second protective layer 130 is disposed on the first protective layer 120.

Specifically, referring to fig. 13 in combination, after coating a photoresist/protective paste on the surface of the first protective layer 120, the second protective layer 130 is formed.

S5: a second opening 131 penetrating to the first opening 121 is formed on the second protective layer 130.

Specifically, referring to fig. 14 in combination, an aluminum pad is opened on the second protective layer 130 using a photolithography process to open the opening, thereby forming a second opening 131.

S6: a conductive metal layer 150 is formed within the first opening 121, the conductive metal layer 150 being disposed on the pad 111.

Specifically, referring to fig. 15, a conductive metal layer 150 is formed in the first opening 121 by an electroplating process, in which the conductive metal layer 150 is a multilayer, and the specific process is as follows: first, a layer of titanium metal is electroplated into the first opening 121 to a thickness of 4-6 μm to form a bonding metal layer 151. The titanium layer has high metal adhesion performance, so that the bonding strength of the subsequent barrier metal layer 153 is ensured, and the second protective layer 130 is adopted to cover the surrounding area, so that the redundant metal layer is not required to be etched by an etching process, and the problem of over-etching is avoided. After the adhesion metal layer 151 is formed, a metal layer is electroplated on the surface of the adhesion metal layer 151 again to form a barrier metal layer 153, wherein the barrier metal layer 153 may be nickel, vanadium chromium, or the like, and the thickness of the barrier metal layer 153 is between 4 μm and 6 μm, so that the barrier metal layer 153 can perform the functions of electrical connection and diffusion resistance. After the barrier metal layer 153 is formed, the wetting metal layer 155 is formed by using an electroplating process again, the wetting metal layer 155 may be a copper layer, the thickness of the wetting metal layer is 2-4 μm, and the wetting metal layer 155 plays a role in transitionally wetting the upper conductive bump 160, so that the bonding force between the conductive bump 160 and the barrier metal layer 153 is improved.

S7, forming a conductive bump 160 in the second opening 131, the conductive bump 160 being disposed on the conductive metal layer 150.

Specifically, referring to fig. 16, after the conductive metal layer 150 is formed, a copper pillar is formed on the wetting metal layer 155 by an electroplating process, so as to form a conductive bump 160, and then a plasma resist stripper (Descum) is used to remove excess photoresist, so as to form a structure with a copper pillar. Here, the second protection layer 130 formed at one time can be used to sequentially realize the sputtering of the metal layer UBM and the formation of the electroplated copper pillar after the opening, thereby greatly reducing the process flow.

It should be noted that, here, in order to facilitate the preparation of the subsequent process, the conductive bump 160 may be made flush with the second protection layer 130.

S8: a third protective layer 140 is disposed on the second protective layer 130.

Specifically, referring to fig. 17, a photoresist/protective paste is coated on the surface of the second passivation layer 130 again to form a third passivation layer 140, wherein the third passivation layer 140 covers the surface of the second passivation layer 130.

S9: a third opening 141 penetrating to the conductive bump 160 is formed on the third protective layer 140.

Specifically, referring to fig. 18, a photolithography process is used to open a groove on the surface of the copper pillar to form an opening, and then a plating process is used again to form a first metal adhesion layer 171 and a first metal anti-diffusion layer 173 in the opening by plating, where the first metal adhesion layer 171 may also be a titanium layer, and the first metal anti-diffusion layer 173 may be an alloy of electroplated nickel and vanadium. After the first metal anti-diffusion layer 173 is formed, micro-etching is performed again on the protection layer, and then sidewalls of the first metal anti-diffusion layer 173 and the first metal adhesion layer 171 are leaked out, forming the third opening 141.

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

Specifically, referring to fig. 1, the solder is filled into the third opening 141 by using an electroplating process or a printing process, the filling of the solder is completed by controlling electroplating parameters or a printing thickness, the residual photoresist is removed by using plasma again to form a copper pillar with the solder, and the solder cap 170 is formed after reflowing again to complete the process.

In the embodiment, the second passivation layer 130 covers the conductive bump 160, the solder cap 170 protrudes from the third passivation layer 140, and the edge of the third opening 141 and the solder cap 170 are spaced apart from each other.

In the method for manufacturing the bump package structure 100 provided in this embodiment, the conductive bump 160 is disposed in the second opening 131, so that the second protection layer 130 is wrapped around the conductive bump 160, thereby protecting the conductive bump 160, avoiding undercut of the conductive bump 160 during etching, effectively ensuring the connection conductive function of the conductive bump 160, and avoiding the problem of dropping the copper pillar bump. Meanwhile, a third passivation layer 140 is additionally disposed on the second passivation layer 130, a third opening 141 is formed on the third passivation layer 140, and an edge of the third opening 141 and the welding cap 170 are disposed at an interval, so that the welding cap 170 is accommodated in the third opening 141 and the welding cap 170 protrudes from the third passivation layer 140. In the actual welding process, the third opening 141 is arranged, so that the effect of reinforcing the strength of the welding structure can be achieved in the tin ball welding process, the solder side wing can be prevented from flowing, and the bridging problem is avoided. Meanwhile, after the tin electroplating layer, when the substrate 200 is soldered, the third protective layer 140 may restrict the solder from flowing when the pad is a circuit, and during the reflow process and the soldering process after the substrate 200 is under-filled with glue, the bottom glue layer may be better filled into the third opening 141 through capillary action, thereby improving the soldering effect. And when the bonding pad on the substrate 200 is a solder ball structure, the solder balls and the solder caps are welded to each other, so that the solder can be contained in a larger space, and the third opening 141 can allow the solder to enter, thereby ensuring the welding accuracy.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (11)

1. A bump package structure, comprising:

a chip having a pad disposed on one side thereof;

the first protective layer is arranged on one side of the chip, the first protective layer covers the welding pad, and a first opening penetrating through the welding pad is formed in the first protective layer;

the second protective layer is arranged on the first protective layer, and a second opening penetrating to the first opening is formed in the second protective layer;

a third protective layer arranged on the second protective layer, wherein a third opening penetrating to the second opening is formed in the third protective layer;

the conductive metal layer is positioned in the first opening and arranged on the welding pad;

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

and a solder cap positioned in the third opening and disposed on the conductive bump;

the second protective layer is wrapped around the conductive bump, the welding cap protrudes from the third protective layer, and the edge of the third opening and the welding cap are arranged at intervals.

2. The bump package structure according to claim 1, wherein the conductive metal layer includes a bonding metal layer, a barrier metal layer and a wetting metal layer, the bonding metal layer is disposed on the bonding pad and partially covers the first protection layer, the barrier metal layer is disposed on the bonding metal layer, the wetting metal layer is disposed on the barrier metal layer, and the conductive bump is disposed on the wetting metal layer.

3. The bump package structure according to claim 1, wherein a first metal anti-diffusion layer is further disposed between the solder cap and the conductive bump, and the first metal anti-diffusion layer is used for blocking atomic diffusion between the solder cap and the conductive bump.

4. The bump package structure according to claim 3, wherein 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 improve a bonding force between the first metal anti-expansion layer and the conductive bump.

5. The bump package structure according to any one of claims 1 to 4, wherein the width of the solder cap is greater than the width of the conductive bump, so that the solder cap covers the conductive bump and partially covers the second protection layer.

6. The bump package structure according to claim 5, wherein the second passivation layer has a plurality of first grooves disposed at least on two sides of the conductive bump and disposed close to the conductive bump, and the solder cap covers the plurality of first grooves and extends into the first grooves.

7. The bump package structure according to claim 6, wherein a buffer layer is further disposed in each first groove, and the thickness of the buffer layer is smaller than the depth of the first groove.

8. The bump package structure according to claim 6, wherein a plurality of second grooves are further disposed on the second passivation layer, the second grooves are at least distributed on two sides of the conductive bump and located in the third opening, and each of the second grooves is spaced apart from the solder cap.

9. The bump package structure according to claim 8, wherein a second metal anti-expansion layer is disposed in each second groove, covers a bottom wall and a side wall of the second groove, and extends to a periphery of an aperture of the second groove.

10. The bump package structure according to claim 9, wherein a second metal adhesion layer is further disposed in each second groove, and the second metal adhesion layer is disposed between the second metal anti-spreading layer and the second protection layer.

11. A method for manufacturing a bump package structure, wherein the method is used for manufacturing the bump package structure as claimed in any one of claims 1 to 10, and the method comprises:

providing a chip with a welding pad;

arranging a first protective layer coated outside the welding pad on one side of the chip;

forming a first opening penetrating to the welding pad on the first protective layer;

disposing a second protective layer on the first protective layer;

forming a second opening penetrating to the first opening on the second protective layer;

forming a conductive metal layer in the first opening, wherein the conductive metal layer is arranged on the welding pad;

forming a conductive bump in the second opening, wherein the conductive bump is arranged on the conductive metal layer;

disposing a third protective layer on the second protective layer;

forming a third opening penetrating to the conductive bump on the third protective layer;

forming a solder cap in the third opening, the solder cap being disposed on the conductive bump;

the second protective layer is wrapped around the conductive bump, the welding cap protrudes from the third protective layer, and the edge of the third opening and the welding cap are arranged at intervals.

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