Joint structure

Abstract

The utility model discloses a bonding structure. The bonding structure comprises a bonding pad; the conductive column is connected to the bonding pad; the protection layers are arranged on the opposite sides, in the transverse direction, of the conductive columns, the protection layers are provided with top faces deviating from the bonding pads, and the conductive columns cover part of the top faces of the protection layers; and the welding flux is positioned above the conductive columns. According to the technical scheme, at least the problems of welding spot cracking, disconnection, interface layering and high resistance caused by solder tin climbing can be solved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and more particularly, to a bonding structure. Background Art

[0002] FOCoS (Fan-Out Chip on Substrate) is one of the advanced packages with tiny solder joints. Figure 1A As shown, solder 20 (e.g., Sn) is used to join two conductive pillars 12, 14 (e.g., copper pillars), and a barrier layer 16 is generally provided on the end surfaces of the conductive pillars 12, 14. However, after soldering, it is found that the solder 20 will creep along the surface to the sidewalls of the conductive pillars 12, 14. The solder 20 that creeps onto the sidewalls of the conductive pillars 12, 14 will react with the material of the conductive pillars 12, 14 (e.g., copper) to form additional intermetallic compounds (IMCs) 30, as shown in FIG. Figure 1B and Figure 1C shown.

[0003] On the other hand, for thin-sized conductive pillars 12 and 14, the volume ratio of IMC 30 to conductive pillars 12 and 14 is too high for the conductive pillars, thus causing more serious reliability problems. Specifically, the rapid formation of IMC 30 may result in unconnected (e.g., Figure 1B Alternatively, the volume of the solder 20 may be severely reduced, resulting in solder necking (as shown in FIG. Figure 1C As shown, this leads to increased resistance, mechanical strength degradation, interface delamination, and solder joint cracking. In specific implementations, the solder joint cracking / loose connection failure rate can be as high as >30%, the interface delamination rate can be as high as >30%, and the high resistance failure rate can be as high as >40%.

[0004] Furthermore, the intermetallic compound (IMC) 30 may further react with the materials of the conductive pillars 12 and 14, resulting in Kirkendall voids. For example, the Sn in the solder 20 reacts with the Cu in the conductive pillars 12 and 14 to form an intermetallic compound called Cu6Sn5. Furthermore, the Cu6Sn5 and Cu further form Cu3Sn, which in turn leads to Kirkendall voids. In multi-chip stacking integration during advanced packaging, this can make heat dissipation more difficult, potentially leading to increased resistance, weakened mechanical strength, and interface delamination, impacting product reliability. Utility Model Content

[0005] In response to the above problems, the present application proposes a bonding structure that can at least eliminate the problems of solder joint cracking, disconnection, interface delamination, and high resistance caused by solder creep.

[0006] According to one aspect of the present application, a bonding structure is provided, which includes: a solder pad; a conductive column connected to the solder pad; a protective layer arranged on the opposite side of the conductive column in the lateral direction, wherein the protective layer has a top surface facing away from the solder pad, and the conductive column covers a portion of the top surface of the protective layer; and solder located above the conductive column.

[0007] In some embodiments, the bonding structure further includes: a dielectric layer located above the pad and below the protection layer, wherein a side of the dielectric layer facing the conductive pillar protrudes beyond a side of the protection layer facing the conductive pillar.

[0008] In some embodiments, the conductive pillar includes a top surface facing away from the pad, the top surface of the conductive pillar has a recess extending toward the pad, and a bottom of the recess is lower than the top surface of the protection layer.

[0009] In some embodiments, the surface roughness of the region of the top surface of the protection layer not covered by the conductive pillars is greater than the surface roughness of the region of the top surface covered by the conductive pillars.

[0010] In some embodiments, the solder fills the recess, wherein the bottom of the solder is lower than the top surface of the protection layer.

[0011] In some embodiments, a top portion of the conductive pillar protrudes outward to cover a portion of a top surface of the protection layer.

[0012] In some embodiments, the bonding structure further includes: another pad, laterally spaced apart from the pad; another conductive column, connected to the other pad; wherein the protective layer extends laterally to the side wall of the other conductive column, and the other conductive column covers another portion of the top surface of the protective layer.

[0013] In some embodiments, the pad is a first pad, the conductive column is a first conductive column, the protective layer is a first protective layer, and the joint structure further includes: a second pad located above the solder; a second conductive column connected between the second pad and the solder; a second protective layer arranged on the opposite side of the second conductive column in the lateral direction, wherein the second protective layer has a top surface facing away from the second pad, and the second conductive column covers a portion of the top surface of the second protective layer.

[0014] In some embodiments, the second conductive pillar includes a top surface facing away from the second pad, and the top surface of the second conductive pillar has a recess extending toward the second pad.

[0015] In some embodiments, the height of the first conductive pillar is greater than the height of the second conductive pillar, and the depth of the recess of the top surface of the first conductive pillar is greater than the depth of the recess of the top surface of the second conductive pillar. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figures 1A to 1C It is a cross-sectional schematic diagram of an existing joint structure.

[0018] Figure 2A and Figure 2B They are respectively a cross-sectional perspective view and a cross-sectional front view of a bonding structure according to an embodiment of the present application.

[0019] Figure 3A 1 is a schematic top view of a bonding structure according to an embodiment of the present application.

[0020] Figure 3B 1 is a schematic top view of a bonding structure according to another embodiment of the present application.

[0021] Figure 4 is a cross-sectional front view of a bonding structure according to another embodiment of the present application.

[0022] Figure 5A and Figure 5B They are Figure 4 Schematic top view of different embodiments of the bonding structure.

[0023] Figure 6A yes Figure 2A and Figure 2B A schematic cross-sectional view of another embodiment of a bonding structure is shown.

[0024] Figure 6B yes Figure 4 A schematic cross-sectional view of another embodiment of a bonding structure is shown.

[0025] Figure 7 2 is a schematic cross-sectional view of a bonding structure according to an embodiment of the present application.

[0026] Figures 8A to 8H 1 is a schematic cross-sectional view of a method of forming a bonding structure according to an embodiment of the present application at multiple stages.

[0027] Figures 9A to 9G 1 is a schematic cross-sectional view of a method of forming a bonding structure according to an embodiment of the present application at multiple stages.

[0028] Figures 10A to 10E Schematic cross-sectional view of a method of bonding two bonding structures through a reflow process at various stages.

[0029] Figures 11A to 11B Schematic cross-sectional views of a method for bonding two bonding structures through a thermocompression bonding process at various stages.

[0030] Figure 12A is a cross-sectional view of a bonding structure according to another embodiment of the present application.

[0031] Figure 12B and Figure 12C They are Figure 12A Plan view at lines AA and BB in.

[0032] Figure 13A is a cross-sectional view of a bonding structure according to yet another embodiment of the present application.

[0033] Figure 13B and Figure 13C They are Figure 13A Plan view at lines AA and BB in.

[0034] Figure 14A is a cross-sectional view of a bonding structure according to yet another embodiment of the present application.

[0035] Figure 14B and Figure 14C They are Figure 14A Plan view at lines AA and BB in.

[0036] Figure 15A is a cross-sectional view of a bonding structure according to yet another embodiment of the present application.

[0037] Figure 15B and Figure 15C They are Figure 15A Plan view at lines AA and BB in.

[0038] Figure 16 is a cross-sectional view of a bonding structure according to yet another embodiment of the present application. DETAILED DESCRIPTION

[0039] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0040] The following disclosure provides many different embodiments or examples for implementing the different features of the provided subject matter. Specific examples of components and arrangements will be described below to simplify the present invention. Of course, these are merely examples and are not intended to limit the present invention. For example, in the following description, forming a first component above or on a second component may include an embodiment in which the first component and the second component are in direct contact, and may also include an embodiment in which an additional component is formed between the first component and the second component so that the first component and the second component may not be in direct contact. Moreover, the present invention may repeatedly refer to numbers and / or letters in various examples. This repetition is merely for simplicity and clarity and does not in itself represent a relationship between the various embodiments and / or configurations discussed.

[0041] In addition, the embodiments and features of the embodiments of the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] An embodiment of the present application provides a bonding structure. Figure 2A and Figure 2B They are respectively a cross-sectional perspective view and a cross-sectional front view of the bonding structure 100 according to an embodiment of the present application. Figure 2A and Figure 2B As shown, the bonding structure 100 may include a first pad 102, a first conductive pillar 110 connected to the first pad 102, a first protective layer 130 disposed on opposite sides of the first conductive pillar 110 in a lateral direction (e.g., direction X), and solder 198 located above the first conductive pillar 110. The solder 198 may be embedded in a base layer 105 and exposed from the base layer 105. The first protective layer 130 has a top surface 130T facing away from the first pad 102, and the first conductive pillar 110 covers a portion of the top surface 130T of the first protective layer 130.

[0043] In the above-described bonding structure 100, by providing a first protective layer 130 on the opposite side of the first conductive pillar 110, and by the first conductive pillar 110 covering a portion of the top surface 130T of the first protective layer 130, an embedded conductive pillar embedded in the first protective layer 130 is formed. The first protective layer 130 can be used to prevent solder 198 from climbing up the sidewalls of the first conductive pillar 110, eliminating the problem of solder creep. The solder joint contains a large amount of conductive material (e.g., copper) to reduce resistance and avoid the generation of excessive IMC, thereby avoiding problems such as solder cracking, disconnection, interface delamination, and high resistance caused by solder creep. In addition, the first protective layer 130 can also enhance the adhesion of the embedded first conductive pillar 110.

[0044] In some embodiments, the surface roughness of the area of ​​the top surface 130T of the first protective layer 130 not covered by the first conductive pillar 110 is greater than the surface roughness of the area of ​​the top surface 130T covered by the first conductive pillar 110. The surface roughness of the area of ​​the top surface 130T of the first protective layer 130 not covered by the first conductive pillar 110 is Ra. In some embodiments, Ra can be in the range of 1-30 nm. Preferably, Ra can be 15 nm. In other words, the portion of the top surface 130T of the first protective layer 130 exposed by the first conductive pillar 110 has a greater roughness, which can enhance the lotus effect, thereby further suppressing the climbing of the solder 198.

[0045] In some embodiments, the first dielectric layer 140 is positioned above the first pad 102 and below the first protective layer 130. Side surfaces 130s and 140s of the first protective layer 130 and the first dielectric layer 140 facing the first conductive pillar 110 may define a step. Specifically, side surface 140s of the first dielectric layer 140 protrudes toward the inside of the first conductive pillar 110 relative to side surface 130s, thereby defining a step between side surfaces 130s and 140s. By defining a step between the first protective layer 130 and the underlying first dielectric layer 140, a latching effect can be achieved, further enhancing the adhesion of the first conductive pillar 110.

[0046] In some embodiments, the material of the first dielectric layer 140 can be PI (polyimide), PBO (poly-p-phenylene benzobisoxazole), BCB (benzocyclobutene), SiN (silicon nitride), SiO (silicon oxide), etc. In some embodiments, the material of the first protective layer 130 can be PI, PBO, BCB, SiN, SiO, etc. The materials of the first protective layer 130 and the first dielectric layer 140 can be the same or different. The material of the first conductive pillar 110 can be Cu, Ag, etc. The material of the solder 198 can be SnAg, SnCu, etc.

[0047] In some embodiments, the thickness of the first dielectric layer 140 may be in the range of 2-20 μm. Preferably, the thickness of the first dielectric layer 140 may be 5 μm. The thickness of the first protective layer 130 is h2. In some embodiments, h2 may be in the range of 5-50 μm. Preferably, h2 may be 30 μm. The width of the first protective layer 130 is d2. In some embodiments, d2 may be in the range of 2-50 μm. Preferably, d2 may be 50 μm. The distance between the opposite sidewalls of the first protective layer 130 facing the first conductive pillar 110 is d4. In some embodiments, d4 may be in the range of 2-50 μm. Preferably, d4 may be 20 μm. In some embodiments, d4 / d2 may be in the range of 0.28-0.80. Preferably, d4 / d2 may be 0.40.

[0048] In some embodiments, the top portion of the first conductive pillar 110 protrudes outward to cover a portion of the top surface 130T of the first protective layer 130. In some embodiments, the first conductive pillar 110 includes a top surface 110T facing away from the first pad, and the top surface 110T of the first conductive pillar 110 has a depression extending toward the first pad 102. The bottom of the depression can be lower than the top surface 130T of the first protective layer 130. Solder 198 fills the depression, so the bottom of the solder 198 is also lower than the top surface 130T of the first protective layer 130.

[0049] In some embodiments, the lateral width of the top surface 110T of the first conductive pillar 110 is greater than the lateral width of the portion surrounded by the first protective layer 130. In some embodiments, the lateral width of the top surface 110T of the first conductive pillar 110 is greater than the lateral width of the first pad 102. The lateral width of the top surface 110T of the first conductive pillar 110 is d5. In some embodiments, d5 may be in the range of 2-50 μm. Preferably, d5 may be 25 μm. In some embodiments, d5 / d2 may be in the range of 0.25-1.00. Preferably, d5 / d2 may be 0.50. In some embodiments, d4 / d5 may be in the range of 0.50-1.00. Preferably, d4 / d5 may be 0.80.

[0050] The height from the bottom of the recess of the first conductive pillar 110 to the bottom level of the first protective layer 130 is h4. In some embodiments, h4 may be in the range of 3-45 μm. Preferably, h4 may be 20 μm. The portion of the first conductive pillar 110 on the top surface 130T of the first protective layer 130 may have a height h4'. The height of the portion of the first conductive pillar 110 surrounded by the first protective layer 130 (i.e., the height h2 of the first protective layer 130) is greater than the height h4' of the first conductive pillar 110 above the first protective layer 130. In some embodiments, h4' may be 2 μm. In some embodiments, h4 / h2 may be in the range of 0.30-0.90. Preferably, h4 / h2 may be 0.67. In some embodiments, h4' / h4 may be in the range of 0.10-0.50. Preferably, h4' / h4 may be 0.10.

[0051] In some embodiments, the bonding structure 100 may further include a first seed layer 111, and the first seed layer 111 is located between the first conductive pillar 110 and the first protection layer 130. In addition, the first seed layer 111 may also be located between the first conductive pillar 110 and the first dielectric layer 140, and between the first conductive pillar 110 and the first pad 102. The first seed layer 111 covers a portion of the top surface 130T of the first protection layer 130. The sidewalls of the first seed layer 111 and the sidewalls of the first conductive pillar 110 may be substantially aligned. The material of the first seed layer 111 may be Cu, Ag, etc. In some embodiments, the material of the first seed layer 111 may be the same as the material of the first conductive pillar 110. The thickness of the first seed layer 111 may be 1000 nm. Preferably, the thickness of the first seed layer 111 can be

[0052] In some embodiments, a barrier layer (not shown) may be provided between the first conductive pillar 110 and the first protective layer 130. The barrier layer may be made of Ti, Ta, W, TaN, etc. The thickness of the barrier layer may be Preferably, the thickness of the barrier layer can be By providing the barrier layer on the sidewall of the first conductive pillar 110 , electromagnetic interference can be reduced.

[0053] In some embodiments, the bonding structure 100 may further include a first metal barrier layer 161, which is located between the solder 198 and the first conductive pillar 110 and conformally located in a recess in the top surface 110T of the first conductive pillar 110. Therefore, the first metal barrier layer 161 may be formed in a dish shape extending toward the first pad 102. The sidewalls of the first metal barrier layer 161, the sidewalls of the first seed layer 111, and the sidewalls of the first conductive pillar 110 may be substantially aligned. The material of the first metal barrier layer 161 may be Ni, Co, FeNi, FeCo, or the like.

[0054] In some embodiments, the thickness of the first metal barrier layer 161 may be in the range of 1-5 μm. Preferably, the thickness of the first metal barrier layer 161 may be 3 μm. In some embodiments, the lateral width of the first metal barrier layer 161 may be equal to the lateral width d5 ​​of the top surface 110T of the first conductive pillar 110. In some embodiments, the height of the solder 198 is h6, measured from the top of the solder 198 to the top surface of the first metal barrier layer 161 above the first protective layer 130. In some embodiments, h6 may be in the range of 3-45 μm. Preferably, h6 may be 20 μm.

[0055] Figure 3A is a schematic top view of a bonding structure 100 according to an embodiment of the present application. Figure 3A The schematic top view may correspond, for example, to Figure 2A The structure in . Figure 3A As shown, the first protection layer 130 may completely cover the first dielectric layer 140 .

[0056] Figure 3B FIG. 1 is a schematic top view of a bonding structure 100 according to another embodiment of the present application. Figure 3A The schematic top view may correspond, for example, to Figure 2B The structure in . Figure 3B As shown, the first protection layer 130 may partially cover the first dielectric layer 140. Figure 3A and Figure 3B As shown in the top view of FIG, the first protection layer 130 may be annular and may surround the first conductive pillar 110.

[0057] Figure 4 is a cross-sectional front view of a bonding structure 200 according to another embodiment of the present application. Figure 4 The illustrated joint structure 200 can be compared in many respects to the above-referenced Figure 2A and Figure 2BThe bonding structure 100 shown is similar. The bonding structure 200 may include a second pad 202, a second conductive pillar 210 connected to the second pad 202, and a second protective layer 230 disposed on the opposite side of the second conductive pillar 210 in the lateral direction (e.g., direction X). The second pad 202 may be embedded in a base layer 205 and exposed by the base layer 205. The second protective layer 230 has a top surface 230T facing away from the second pad 202, and the second conductive pillar 210 covers a portion of the top surface 230T of the second protective layer 230. The material of the second conductive pillar 210 may be Cu, Ag, etc. When the bonding structure 200 is bonded to another structure, solder may be formed above the second conductive pillar 210.

[0058] In the above-described bonding structure 200, a second protective layer 230 is provided on the opposite side of the second conductive pillar 210, with the second conductive pillar 210 covering a portion of the top surface 230T of the second protective layer 230. This forms an embedded conductive pillar. The second protective layer 230 can prevent solder from climbing up the sidewalls of the second conductive pillar 210, eliminating solder creep. The second protective layer 230 can also enhance the adhesion of the embedded second conductive pillar 210.

[0059] The surface roughness of the top surface 230T of the second protective layer 230 not covered by the second conductive pillars 210 is greater than the surface roughness of the top surface area covered by the second conductive pillars 210. The surface roughness of the top surface area of ​​the second protective layer 230 not covered by the first conductive pillars 110 can be in the range of 1-30 nm, preferably 15 nm. The portion of the top surface 130T of the second protective layer 230 exposed by the second conductive pillars 210 has a greater roughness, which can enhance the lotus effect and further suppress solder creep.

[0060] The material of the second protective layer 230 can be PI, PBO, BCB, SiN, SiO, etc. The height of the second protective layer 230 is h8. In some embodiments, h8 can be in the range of 5-50 μm. Preferably, h8 can be 17 μm. The width of the second protective layer 230 is d8. In some embodiments, d8 can be in the range of 2-50 μm. Preferably, d8 can be 50 μm.

[0061] The distance between the opposite side walls of the second protective layer 230 facing the second conductive pillar 210 is d10, and d10 may be in the range of 2-50 μm. Preferably, d10 may be 20 μm. The lateral width of the top surface 210T of the second conductive pillar 210 is d11, and d11 may be in the range of 2-50 μm. Preferably, d11 may be 25 μm. In some embodiments, d10 / d8 may be in the range of 0.25-0.8. Preferably, d10 / d8 may be 0.40. In some embodiments, d11 / d8 may be in the range of 0.25-1.00. Preferably, d11 / d8 may be 0.50. In some embodiments, d10 / d11 may be in the range of 0.50-1.00. Preferably, d10 / d11 may be 0.80.

[0062] The height from the bottom of the recess of the top surface 210T of the second conductive pillar 210 to the bottom level of the second protective layer 230 is h10. In some embodiments, h10 may be in the range of 2-30 μm. Preferably, h10 may be 15 μm. The portion of the second conductive pillar 210 on the top surface of the second protective layer 230 may have a height h10'. In some embodiments, h10' may be 2 μm. In some embodiments, h10 / h8 may be in the range of 0.60-0.90. Preferably, h10 / h8 may be 0.88. In some embodiments, h10' / h10 may be in the range of 0.10-0.50. Preferably, h10' / h10 may be 0.13.

[0063] The bonding structure 200 may further include a second dielectric layer 240, which is located above the second pad 202 and below the second protective layer 230. In some embodiments, the material of the second dielectric layer 240 may be PI, PBO, BCB, SiN, SiO, etc. The thickness of the second dielectric layer 240 may be in the range of 2-20 μm. Preferably, the thickness of the second dielectric layer 240 may be 5 μm.

[0064] The second seed layer 211 is located between the second conductive pillar 210 and the second protective layer 230. The material of the second seed layer 211 can be Cu, Ag, etc. The thickness of the second seed layer 211 can be Preferably, the thickness of the second seed layer 211 can be The material of the second metal barrier layer 261 can be Ni, Co, FeNi, FeCo, etc. In some embodiments, the thickness of the second metal barrier layer 261 can be in the range of 1-5 μm. Preferably, the thickness of the second metal barrier layer 261 can be 3 μm. The second metal barrier layer 261 can also be formed in a dish shape extending toward the second pad 202.

[0065] A barrier layer (not shown) may also be provided between the second conductive pillar 210 and the second protective layer 230. The material of the barrier layer may be Ti, Ta, W, TaN, etc. The thickness of the barrier layer may be Preferably, the thickness of the barrier layer can be By providing a barrier layer on the sidewall of the second conductive pillar 210 , electromagnetic interference can be reduced.

[0066] Figure 4 The total height of the second conductive pillar 210 can be less than Figure 2A and Figure 2B In some embodiments, Figure 4 The second conductive column 210 in the embodiment may be referred to as a pad. Figure 4 In the illustrated embodiment, a surface layer 263 may be further provided on the second metal barrier layer 261. Surface layer 263 may also be formed in a dish shape extending toward the second pad 202. The material of surface layer 263 may be Au, etc. The thickness of surface layer 263 may be in the range of 0.01-0.8 μm. Preferably, the thickness of surface layer 263 may be 0.25 μm.

[0067] Figure 5A and Figure 5B They are Figure 4 Schematic top view of different embodiments of the bonding structure 200. Figure 5A As shown, the second protection layer 230 may completely cover the second dielectric layer 240. Figure 5B As shown, the second protection layer 230 may partially cover the second dielectric layer 240 .

[0068] Figure 6A yes Figure 2A and Figure 2B FIG. 1 is a schematic cross-sectional view of another embodiment 100 ′ of the bonding structure 100 . Figure 6A As shown, Figure 2A and Figure 2B The difference of the illustrated embodiment is that an additional first metal layer 171 is disposed on the first metal barrier layer 161, and the first metal layer 171 may be located between the first metal barrier layer 161 and the solder 198. In one example, the materials of the first conductive pillar 110, the first metal barrier layer 161, the first metal layer 171, and the solder 198 may be Cu, Ni, Cu, and SnAg, in that order.

[0069] Figure 6B yes Figure 4 FIG. 2 is a schematic cross-sectional view of another embodiment 200 ′ of the bonding structure 200 . Figure 6B As shown, Figure 4The illustrated embodiment differs in that an additional second metal layer 271 is disposed on the second metal barrier layer 261, and the second metal layer 271 is located between the second metal barrier layer 261 and the surface layer 263. In one example, the materials of the second conductive pillar 210, the second metal barrier layer 261, the second metal layer 271, and the surface layer 263 can be, in order, Cu, Ni, Cu, or Pd, Au. Providing the first and second metal layers 171 and 271 on the first and second metal barrier layers 261 can be used to control solder IMC.

[0070] The following will refer to Figure 2A and Figure 2B The illustrated joining structure 100 and Figure 4 The bonding structure 200 shown is used to illustrate various embodiments of the present application, but it should be understood that various embodiments may also be used. Figure 6A and Figure 6B The joining structures 100 ′, 200 ′ of the illustrated embodiment.

[0071] Figure 7 is a schematic cross-sectional view of a bonding structure 300 according to an embodiment of the present application. Figure 7 The bonding structure 300 shown is a structure obtained by bonding the bonding structures 100 and 200 together by solder 198. In this embodiment, the bonding structure 100 is bonded above the bonding structure 200, but in other embodiments, the opposite direction may be used. Figure 7 As shown, solder 198 joins the first conductive pillar 110 and the second conductive pillar 210 to each other.

[0072] In some embodiments, the height h21 of the first conductive pillar 110 is greater than the height h22 of the second conductive pillar 210. In some embodiments, the height h4 of the first conductive pillar 110 is greater than the height h10 of the second conductive pillar 210. The depth of the recess of the top surface 110T of the first conductive pillar 110 is greater than the depth of the recess of the top surface 210T of the second conductive pillar 210. In other words, the taller first conductive pillar 110 has a deeper recess.

[0073] Embodiments of the present application also provide a method for forming a bonding structure. Figures 8A to 8H 1 is a cross-sectional view of a method of forming a bonding structure 100 according to an embodiment of the present application at multiple stages. Figure 8A As shown, a base layer 105 and a first pad 102 disposed in the base layer 105 are provided. A first dielectric layer 140 is formed on the base layer 105. The first dielectric layer 140 defines an opening 802, and the opening 802 exposes the first pad 102.

[0074] refer to Figure 8BAs shown, a first protective layer 130 is formed on the first dielectric layer 140. The first protective layer 130 defines an opening 804 located above the opening 802. The width of the opening 804 may be greater than the width of the opening 802. Figure 8C As shown, a first seed layer 111 is formed on the first protection layer 130 , the first dielectric layer 140 and the first pad 102 , for example, by a sputtering process.

[0075] refer to Figure 8D As shown, a photoresist layer 822 is formed on the first seed layer 111, and the photoresist layer 822 defines an opening 806. The size of the opening 806 can be the same as the top width of the first conductive pillar to be formed subsequently.

[0076] refer to Figure 8E As shown, the openings 802 and 804 (see Figure 8D ) is filled with a conductive material to form a first conductive pillar 110. The top of the first conductive pillar 110 covers a portion of the top surface of the first protective layer 130. Due to the electroplating chemistry, the top of the first conductive pillar 110 appears as a lateral protrusion extending laterally above the top surface of the first protective layer 130, with a recess formed in the center. Then, a first metal barrier layer 161 is formed on the first conductive pillar 110, and solder 198 is formed on the first metal barrier layer 161.

[0077] refer to Figure 8F As shown, the photoresist layer 822 is removed (see Figure 8E ), and remove the first seed layer 111 below the photoresist layer 822. Figure 8G As shown, reflow of the solder 198 is performed so that the solder 198 is shaped into a spherical shape.

[0078] refer to Figure 8H As shown, a surface treatment is performed on the exposed portion of the top surface 130T of the first protective layer 130 so that the surface roughness of the exposed portion of the top surface 130T is increased.

[0079] Figures 9A to 9G 2 is a schematic cross-sectional view of a method of forming a bonding structure 200 according to an embodiment of the present application at multiple stages. Figure 9A As shown, a base layer 105 and a second pad 202 disposed in the base layer 105 are provided. A second dielectric layer 240 is formed on the base layer 105. The second dielectric layer 240 defines an opening 902, and the opening 902 exposes the second pad 202.

[0080] refer to Figure 9B As shown, a second protection layer 230 is formed on the second dielectric layer 240. The second protection layer 230 defines an opening 904. The width of the opening 904 can be the same as the width of the opening 902.

[0081] refer to Figure 9C As shown, a second seed layer 211 is formed on the second protection layer 230 , the second dielectric layer 240 and the second pad 202 , for example, by a sputtering process.

[0082] refer to Figure 9D As shown, a photoresist layer 922 is formed on the second seed layer 211 . The photoresist layer 922 defines an opening 906 . The opening 906 is located above the opening 904 .

[0083] refer to Figure 9E As shown, the openings 902 and 904 (see Figure 9D ) is filled with a conductive material to form a second conductive pillar 210. The top of the second conductive pillar 210 covers a portion of the top surface of the second protective layer 230. Due to the electroplating chemistry, the top of the second conductive pillar 210 appears as a lateral protrusion extending laterally above the top surface of the second protective layer 230, with a recess formed at the center. Then, a second metal barrier layer 261 is formed on the second conductive pillar 210, and a surface layer 263 is formed on the second metal barrier layer 261.

[0084] refer to Figure 9F As shown, the photoresist layer 922 is removed (see Figure 9E ), and remove the seed layer 211 under the photoresist layer 922.

[0085] refer to Figure 9G As shown, a surface treatment is performed on the exposed portion of the top surface 230T of the second protective layer 230 so that the surface roughness of the exposed portion of the top surface 230T is increased.

[0086] Figures 10A to 10E Schematic cross-sectional view of a method for bonding two bonding structures 100 and 200 at multiple stages by a mass reflow process. Figure 10A As shown, the engagement structures 100, 200 are vertically aligned.

[0087] Then refer to Figure 10B As shown, the joining structures 100, 200 are then attached together. Figure 10C As shown, a reflow process is performed to connect the solder 198 to the second conductive pillar 210 .

[0088] refer to Figure 10D As shown, an underfill 1002 is formed, and the underfill 1002 covers the solder 198, the first conductive pillar 110 and the second conductive pillar 210. Figure 10EAs shown, a curing process is performed to harden the underfill 1002. In some embodiments, the underfill 1002 may be made of an epoxy resin-based material. The bonding structure 400 is formed.

[0089] Figures 11A to 11B Schematic cross-sectional view of a method of bonding two bonding structures 100 and 200 at various stages using a thermal compression bond process. Figure 11A As shown, a filling material 1004 is formed on the first protective layer 130 and the solder 198, and then the bonding structure is aligned. The filling material 1004 can be any of the following: TCCUF (Thermal Compression Capillary Underfill), TCNCF (Thermal Compression Non-Conductive Film), or TCNCP (Thermal Compression Non-Conductive Paste).

[0090] refer to Figure 11B As shown, a thermocompression bonding process is performed to connect the solder 198 to the second conductive pillar 210, and the filling material 1004 covers the solder 198, the first conductive pillar 110, and the second conductive pillar 210. Then, a curing process is performed to harden the filling material 1004, thereby forming the bonding structure 500.

[0091] Can be achieved through Figures 10A-10E or Figures 11A-11B The method described joins a plurality of joined structures 100, 200 together, such as Figure 12A As shown. In some embodiments, the spacing s1 between adjacent first protective layers 130 can be in the range of 0-100 μm. Preferably, the spacing s1 can be 10 μm. The vertical distance s2 between the first dielectric layer 140 and the second dielectric layer 240 can be in the range of 10-120 μm. Preferably, the spacing s2 can be 80 μm.

[0092] Figure 12B and Figure 12C They are Figure 12A Plan view at lines AA and BB in. Combined Figure 12B and Figure 12C As shown, in this embodiment, the first protection layer 130 does not completely cover the first dielectric layer 140 , and the second protection layer 230 does not completely cover the second dielectric layer 240 .

[0093] Figure 13Ais a cross-sectional view of a bonding structure according to yet another embodiment of the present application. Figure 13B and Figure 13C They are Figure 13A Plan view at lines AA and BB in. 13A to 13C As shown, in this embodiment, the first protective layer 130 does not completely cover the first dielectric layer 140, and the second protective layer 230 completely covers the second dielectric layer 240. Specifically, for two adjacent second conductive pillars 210, the second protective layer 230 extends laterally from the sidewall of one second conductive pillar 210 to the sidewall of the other second conductive pillar 210. The two second conductive pillars 210 respectively cover a portion of the top surface of the second protective layer 230.

[0094] Figure 14A is a cross-sectional view of a bonding structure according to yet another embodiment of the present application. Figure 14B and Figure 14C They are Figure 14A Plan view at lines AA and BB in. 14A to 14C As shown, the first protective layer 130 completely covers the first dielectric layer 140, while the second protective layer 230 does not completely cover the second dielectric layer 240. Specifically, for two adjacent first conductive pillars 110, the first protective layer 130 extends laterally from the sidewall of one first conductive pillar 110 to the sidewall of the other first conductive pillar 110. The two first conductive pillars 110 each cover a portion of the top surface of the first protective layer 130.

[0095] Figure 15A is a cross-sectional view of a bonding structure according to yet another embodiment of the present application. Figure 15B and Figure 15C They are Figure 15A Plan view at lines AA and BB in. Figures 15A to 15C As shown, the first protection layer 130 completely covers the first dielectric layer 140 , and the second protection layer 230 completely covers the second dielectric layer 240 .

[0096] Figure 16 FIG is a cross-sectional view of a bonding structure according to another embodiment of the present application. Figure 16 In this embodiment, the bonding structure 100 can be bonded to an existing conductive pillar 2000 (which can be referred to as a pad). The sidewalls of the conductive pillar 2000 are not provided with a protective layer. Furthermore, the top surface of the conductive pillar 2000 is flat and has no depressions.

[0097] The above technical solution provided by this application can prevent tin climbing and prevent solder from contacting the bottom conductive pillar. The solder joint cracking / non-connection failure rate can be reduced to <5%. The interface delamination failure can be reduced to <5%). The low resistance failure rate can be reduced to <5%. It provides high-reliability fine solder joints. The conductive pillars have strong adhesion. The volume shrinkage of fine solder is low. Copper electromigration is reduced. This application can be applied to all products with solder joints, such as: FOCoS, FOCoS-B (FOCoS bridge), 2.5D (2.5-dimensional), 3DIC (3-dimensional integrated circuit) and FOSub (fan-out substrate) and other products.

[0098] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A joining structure, characterized in that: include: pads; a conductive column connected to the pad; a protective layer disposed on a side opposite to the conductive pillar in a lateral direction, wherein the protective layer has a top surface facing away from the pad, and the conductive pillar covers a portion of the top surface of the protective layer; Solder is located on the conductive pillar.

2. The joining structure according to claim 1, wherein: Also includes: A dielectric layer is located above the pad and below the protective layer, wherein a side of the dielectric layer facing the conductive pillar protrudes beyond a side of the protective layer facing the conductive pillar.

3. The joining structure according to claim 1, wherein: The conductive pillar includes a top surface facing away from the pad, the top surface of the conductive pillar has a recess extending toward the pad, and a bottom of the recess is lower than the top surface of the protection layer.

4. The joining structure according to claim 1, wherein: The surface roughness of a region of the top surface of the protection layer not covered by the conductive pillar is greater than the surface roughness of a region of the top surface covered by the conductive pillar.

5. The joining structure according to claim 3, wherein: The solder fills the recess, wherein the bottom of the solder is lower than the top surface of the protection layer.

6. The joining structure according to claim 1, wherein: A top portion of the conductive pillar protrudes outward to cover the portion of the top surface of the protection layer.

7. The joining structure according to claim 1, wherein: Also includes: another pad, spaced laterally from the pad; another conductive column connected to the another pad; The protection layer extends laterally to the sidewall of the other conductive pillar, and the other conductive pillar covers another portion of the top surface of the protection layer.

8. The joining structure according to claim 1, wherein: The pad is a first pad, the conductive column is a first conductive column, the protective layer is a first protective layer, and the bonding structure further includes: a second solder pad located above the solder; a second conductive column connected between the second pad and the solder; The second protection layer is disposed on a side opposite to the second conductive column in a lateral direction, wherein the second protection layer has a top surface facing away from the second pad, and the second conductive column covers a portion of the top surface of the second protection layer.

9. The joining structure according to claim 8, wherein: The second conductive pillar includes a top surface facing away from the second pad, and the top surface of the second conductive pillar has a recess extending toward the second pad.

10. The joining structure according to claim 9, wherein: The height of the first conductive pillar is greater than that of the second conductive pillar, and the depth of the recess of the top surface of the first conductive pillar is greater than the depth of the recess of the top surface of the second conductive pillar.

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