Integrated circuit based on repairable welding spots and preparation method thereof

Abstract

The invention relates to the field of semiconductor circuit manufacturing, in particular to an integrated circuit based on a repairable welding spot and a preparation method of the integrated circuit, the integrated circuit adopts the repairable welding spot, the repairable welding spot is brazed on a circuit substrate bonding pad, and a functional film layer, a repairing low brazing filler metal layer and a diffusion barrier layer are arranged between welding spot brazing filler metal and the substrate bonding pad; when the repairable welding spot generates a crack, the functional film layer is excited to perform self-propagating exothermic reaction, so that the repair brazing filler metal layer is molten and flows to fill the crack; and after the molten repairing brazing filler metal layer is cooled and solidified in the cracks, the electrical function integrity of the integrated circuit based on the repairable welding spots is maintained. When the integrated circuit designed by the invention is used for repairing the welding spots, the welding spots do not need to be rewelded, so that the repairing process flow of the integrated circuit can be greatly saved, semiconductor and electric fitting process procedures are compatible, a relatively good welding spot crack repairing effect can be realized, and relatively high popularization and application are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor circuit manufacturing, in particular to an integrated circuit based on a repairable solder joint and a preparation method thereof. BACKGROUND

[0002] The development of semiconductor integrated circuit technology is closely related to the development of electronic packaging technology. Although the size of components and the size of solder joints are becoming smaller and smaller, the mechanical, electrical and thermal loads they need to bear are becoming heavier and heavier, making the solder joints more prone to damage during application, thereby degrading the performance of components and even functional units, reducing reliability, and even causing the failure of the entire system.

[0003] In the prior art, when the solder joint fails, the solder joint is usually repaired by re-soldering, which is costly and complex.

[0004] Therefore, there is an urgent need for an integrated circuit that has a more efficient repair method for solder joint failure. SUMMARY

[0005] Therefore, the present application discloses an integrated circuit based on a repairable solder joint and a preparation method thereof to solve the above problems.

[0006] An integrated circuit based on a repairable solder joint comprises:

[0007] The integrated circuit uses a repairable solder joint during packaging. The repairable solder joint is brazed on the substrate pad of the circuit. A functional film layer, a repair solder layer and a diffusion barrier layer are further provided between the solder joint filler and the substrate pad.

[0008] The diffusion barrier layer covers the functional film layer and the repair solder layer, and is used to isolate the solder joint filler from the repair solder layer.

[0009] The repair solder layer is arranged between the functional film layer and the diffusion barrier layer, has a smaller size than the functional film layer, and is made of a filler material with a lower melting temperature than the solder joint filler.

[0010] The functional film layer is arranged on the circuit substrate pad, has a smaller size than the substrate pad, and is made of a thin film material capable of undergoing a self-propagating exothermic reaction. The thin film material is composed of two or more overlapped thin film materials.

[0011] When the repairable solder joint produces a crack, the functional film layer is excited to undergo a self-propagating exothermic reaction, causing the repair solder layer to melt and flow into the crack. After the melted repair solder layer cools and solidifies in the crack, the electrical function of the integrated circuit based on the repairable solder joint is maintained.

[0012] A preparation method of an integrated circuit based on a repairable solder joint comprises:

[0013] S1, cleaning the surface of the substrate, sputtering and depositing a functional film layer on the substrate;

[0014] S2, printing or electroplating to prepare a repair solder layer on the functional film layer

[0015] S3, electroplating or sputtering to prepare a diffusion barrier layer on the repair solder layer;

[0016] S4, soldering a welding spot on the diffusion barrier layer to complete the welding.

[0017] The beneficial effects of the present application include:

[0018] By prepositioning the functional film layer and the repair solder layer on the substrate, the repair of the welding spot damage is achieved. When the welding spot crack initiation, propagation and cracking failure are detected, the prepositioned functional film layer will have a self-propagating reaction, which will release a large amount of heat, melt the repair solder layer and drive it to flow into the welding spot crack, and realize the metallurgical reaction with the soldering spot solder, thereby achieving the repair of the welding spot. This process does not require re-soldering of the welding spot, and can greatly save the repair process flow of the integrated circuit.

[0019] The integrated circuit based on the repairable welding spot designed in the present application is compatible with semiconductor and electrical process, and can achieve good welding spot crack repair effect, and has strong popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of a BGA type flip-chip device in the embodiments of the present application;

[0021] Figure 2 is a schematic diagram of a repairable welding spot used in a BGA type flip-chip device in the embodiments of the present application;

[0022] Figure 3 is a flowchart of the preparation method of the integrated circuit based on the repairable welding spot in the embodiments of the present application;

[0023] The drawings show that: 1 is the soldering spot solder, 2 is the solder pad, 3 is the diffusion barrier layer, 4 is the repair solder layer, 5 is the functional film layer, and 6 is the substrate. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme, characteristics and advantages of the present application more clear, in order to make the technical personnel in the art better understand the technical scheme of the present application, the following will be further introduced in detail in combination with the drawings and examples.

[0025] Example 1:

[0026] This embodiment includes an integrated circuit based on repairable solder joints, wherein the integrated circuit employs repairable solder joints during packaging; such as Figure 1 As shown, this embodiment uses a BGA-type flip-chip device as an example. Repairable solder joints are brazed onto the substrate pad 2 of the circuit, as shown... Figure 2 As shown, a functional film layer 5, a repair solder layer 4, and a diffusion barrier layer 3 are also provided between the solder joint filler metal 1 and the substrate pad 2.

[0027] The diffusion barrier layer 3 covers the functional film layer 5 and the repair solder layer 4, and is used to isolate the solder joint solder 1 from the repair solder layer 4.

[0028] The repair solder layer 4 is disposed between the functional film layer 5 and the diffusion barrier layer 3, and its size is smaller than that of the functional film layer 5. The solder material selected has a melting temperature lower than that of the solder joint solder 1.

[0029] The functional film layer 5 is disposed on the circuit substrate pad 2, and its size is smaller than that of the substrate pad 2. It is made of a thin film material capable of undergoing a self-propagating exothermic reaction. The thin film material is composed of two or more overlapping thin film materials. A self-propagating reaction is a high-speed exothermic reaction with a formation rate of 1-100 m / s, and the instantaneous temperature of the exothermic reaction can reach 1000-3000℃. Due to its instantaneous high-energy self-propagating characteristics, it is often used in fields such as ceramic / metal interconnects, micro / nano unit connections, target / backplane interconnects, and stainless steel and amorphous material connections. Common material systems capable of undergoing self-propagating reactions include Al / Ni, Al / Ti, Al / Zr, Ni / Si, Ti / Si, and Al / Pd.

[0030] The thickness of the functional film layer 5 is determined based on the heat required to melt the repair solder layer 4, so that the heat generated by the self-propagating exothermic reaction is not less than the heat required to melt the repair solder layer 4. Typically, the thickness of the functional film layer 5 is between tens and hundreds of micrometers.

[0031] Furthermore, the functional film layer 5 is selected based on the material of the substrate 6 or the pads, so that the functional film layer 5 adheres to the substrate 6 or the pads during a self-propagating reaction. As a preferred embodiment, the functional film layer 5 is selected from commonly used semiconductor materials such as Ni, Al, and Si, such as Al / Ni, Ti / Al, etc. This provides good compatibility with the substrate 6 and the solder, and can also be easily fabricated using existing technologies and equipment in microelectronics manufacturing.

[0032] The repair solder layer 4 is selected from a low-melting-point solder material with good fluidity, used for repairing the damage defects of the solder joint, avoiding excessive other unintended heat affected zone, and the melting temperature of the solder material is lower than that of the solder joint. After melting, the repair solder layer 4 can physically or metallurgically react with the solder joint solder 1 to repair the crack, that is, it should have a certain fluidity after melting, and have good crack wetting and filling capacity. The size and thickness of the repair solder layer 4 should ensure that the liquid solder can flow into the damaged area of the solder joint when it is heated and melted, and realize the repair function. In the actual engineering application process, the low-melting-point solder should not be too much, so as not to affect the overall performance of the solder joint. In the conventional electronic assembly process, the solder composition containing In, Bi and other elements generally has a lower melting point and good fluidity, and has good metallurgical compatibility with the mainstream solder (such as SnPb, SnAgCu, etc.), which meets the basic characteristics of the repair solder layer 4. As an preferred embodiment, the repair solder layer 4 is selected from In-based solder.

[0033] Further, the size of the repair solder layer 4 is smaller than the size of the functional film layer 5, so as to ensure that the solder material can be directly soldered to the substrate.

[0034] The substrate pad 2 is made of one of Cu / Ni structure, solderable metal, and plated material.

[0035] Further, the functional film layer 5 and the repair solder layer 4 are embedded in the solder joint, without affecting the structural strength of the solder joint. This structure can maintain the strength of the substrate body, and also can ensure that the molten solder of the solder joint is more easily flowed into the damaged area of the solder joint structure during the self-repairing process.

[0036] Since the repair solder layer 4 and the solder joint may have a metallurgical reaction during the formation of the solder joint, affecting the function of the repair solder layer 4, the diffusion barrier layer 3 is designed to isolate the functional film layer 5 and the repair solder layer 4 from the solder joint. The diffusion barrier layer 3 is partially or completely dissolved into the solder joint solder 1 and the repair solder during the formation of the solder joint.

[0037] Further, the diffusion barrier layer 3 should have good solderability, and does not need to completely cover the exposed pad / substrate, so as to ensure that the solder joint and the pad form a soldered connection, thereby maintaining the mechanical properties. Of course, if the diffusion barrier layer 3 has good adhesion strength with the pad, it can also cover the exposed pad / substrate area.

[0038] As an preferred embodiment, in this embodiment, the diffusion barrier layer 3 has a size larger than that of the repair solder layer 4, and is made of Ni or Cu, with a thickness of 0.2 μm to 0.6 μm.

[0039] When the repairable solder joint generates a crack, the functional film layer 5 is excited to carry out a self-propagating exothermic reaction, so that the repair solder layer 4 is melted and flows to fill into the crack; after the melted repair solder layer 4 cools and solidifies in the crack, the electrical function of the integrated circuit based on the repairable solder joint is maintained.

[0040] Further, the functional film layer 5 is excited to carry out a self-propagating exothermic reaction, which is achieved by current excitation or laser excitation; when laser excitation is adopted, the functional film layer 5 further comprises an ignition strip extending out of the solder joint for laser ignition.

[0041] About 70% of electronic device failures are caused by the failure of packaging and assembly solder joints. The mismatch of thermal expansion coefficient, impact and vibration load and other factors cause the crack initiation and expansion of the solder joint. The integrated circuit based on the repairable solder joint designed in the present application contains repairable solder joints which are not isolated but are combined with the integrated circuit as a whole system, so that the crack of the solder joint can be detected, identified and repaired in the integrated circuit system. Specifically, when a cracked solder joint is detected in the integrated circuit, the cracked solder joint is excited by current, and the circuit based on the repairable solder joint is self-healed to restore the performance. Compared with the prior art which requires re-soldering of the circuit when individual solder joints are damaged, the integrated circuit based on the repairable solder joint designed in the present application has the ability of automatic repair, and is more targeted in the repair process.

[0042] Embodiment 2:

[0043] The present embodiment includes a preparation method of an integrated circuit based on a repairable solder joint, which is used to prepare the integrated circuit based on a repairable solder joint in Embodiment 1, as shown in Figure 3 The preparation method comprises the following steps:

[0044] S1, cleaning the surface of the substrate, and sputtering and depositing a functional film layer on the substrate.

[0045] S2, preparing a repair solder layer on the functional film layer by printing or electroplating; the size of the repair solder layer is smaller than that of the functional film layer.

[0046] Further, the repair solder layer is prepared by reflow soldering or electroplating.

[0047] S3, preparing a diffusion barrier layer on the repair solder layer by electroplating or sputtering.

[0048] S4, soldering a solder joint on the diffusion barrier layer to complete the welding.

[0049] When the solder joint is soldered on the diffusion barrier layer, the soldering material and process used belong to the conventional soldering process.

[0050] Finally, it should be noted that the above only describes some embodiments of the present application, and for those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be conceived without departing from the principles and spirits of the present application, the protection scope of the present application is defined by the appended claims and their equivalents, and the above behaviors should be covered within the protection scope of the present application.

Claims

1. An integrated circuit based on a repairable solder joint, characterized by The integrated circuit adopts a repairable solder joint in packaging, the repairable solder joint is brazed on a substrate pad of the circuit, and a functional film layer, a repair solder layer and a diffusion barrier layer are arranged between the solder joint and the substrate pad; The diffusion barrier layer covers the functional film layer and the repair solder layer, and is used for isolating the solder joint from the repair solder layer; The repair solder layer is arranged between the functional film layer and the diffusion barrier layer, has a size smaller than that of the functional film layer, and is made of a solder material having a lower melting temperature than the solder joint; The functional film layer is arranged on the substrate pad of the circuit, has a size smaller than that of the substrate pad, and is made of a thin film material capable of generating a self-propagating exothermic reaction; and the thin film material is composed of two or more than two overlapped thin film materials; When the repairable solder joint generates a crack, the functional film layer is excited to generate a self-propagating exothermic reaction, so that the repair solder layer is melted and flows to fill the crack; after the melted repair solder layer is cooled and solidified in the crack, the electrical function of the integrated circuit based on the repairable solder joint is maintained.

2. The repairable-joint-based integrated circuit according to claim 1, wherein, The functional film layer and the repair solder layer are embedded in the solder joint, and do not affect the structural strength of the solder joint.

3. The repairable-joint-based integrated circuit according to claim 1, wherein, The functional film layer generates heat through a self-propagating exothermic reaction, and the heat is not less than the heat required for melting the repair solder layer.

4. The repairable-joint-based integrated circuit according to claim 1, wherein, The repair solder layer is made of a brazing material with low melting point and good fluidity, and can generate a physical or metallurgical reaction with the solder joint after being melted, so as to repair the crack.

5. The repairable-joint-based integrated circuit according to claim 1, wherein, The substrate pad is made of one of Cu / Ni structure, solderable metal and plated material.

6. The repairable-joint-based integrated circuit according to claim 1, wherein, The diffusion barrier layer is partially or entirely dissolved into the solder joint and the repair solder layer during formation of the solder joint.

7. The reworkable solder joint-based integrated circuit of claim 1, wherein, The diffusion barrier layer has a size greater than that of the repair solder layer, is made of Ni or Cu, and has a thickness of 0.2 μm to 0.6 μm.

8. The reworkable solder joint based integrated circuit of claim 1, wherein, The functional film layer is excited to generate a self-propagating exothermic reaction through current excitation or laser excitation; when the laser excitation is adopted, the functional film layer further includes an ignition strip exposed outside the solder joint, and is used for ignition.

9. A method for manufacturing a reworkable solder joint based integrated circuit for manufacturing a reworkable solder joint based integrated circuit according to any one of claims 1 to 8, characterized in that The method comprises the following steps: S1, cleaning a substrate surface, and sputtering and depositing a functional film layer on the substrate; S2, printing or electroplating to prepare a repair solder layer on the functional film layer; S3, electroplating or sputtering to prepare a diffusion barrier layer on the repair solder layer; S4, brazing a solder joint on the diffusion barrier layer to complete welding.

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