Novel integrated circuit USB bonding process

Abstract

The invention discloses a novel integrated circuit USB bonding process, and belongs to the technical field of integrated circuits. A novel integrated circuit ultrasonic welding bonding process comprises the following steps: preparing a substrate bonding pad and a wafer bonding pad; carrying out pre-balling on the upper part of the substrate bonding pad; carrying out ball mounting on the bottom of the wafer bonding pad; and bonding the substrate bonding pad and the wafer bonding pad. According to the invention, the original combination mode of the substrate and the solder balls is improved; the defect of insufficient strength after bonding is avoided, and an improvement direction is provided for future process selection; and meanwhile, a bonding area can be focused, and the necessity of considering full gold plating of a bonding pad in a substrate factory is reduced, so that the straight material cost is reduced, and the economic benefit is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and particularly relates to a novel integrated circuit USB bonding process. Background Art

[0002] In the current USB (Ultrasonic bond) operation process, the key way to judge the bonding strength is the push force test. Through this test method, the main break point occurrence modes can be clearly identified, as follows:

[0003] The first type: IMC layer fracture:

[0004] This type of fracture occurs between the wafer pad and the Bump ball. The IMC layer (Intermetallic Compound Layer) plays a key role in the connection structure of integrated circuits. It is formed by the chemical reaction between different metal materials when they come into contact under certain conditions. However, in the actual USB operation process, due to the influence of various complex stresses and environmental factors, the IMC layer may fracture, which will seriously affect the stability and reliability of the entire circuit connection.

[0005] The second type: Bump (metal bump) ball fracture (ideal state):

[0006] In an ideal situation, when the push force test is carried out, the fracture of the Bump ball is considered a relatively good state. This is because the Bump ball plays an important connection role in the entire bonding structure, and its fracture mode reflects the quality of the bonding process and the performance of the materials to a certain extent. If the fracture of the Bump ball occurs in a relatively uniform and predictable manner within a reasonable stress range, it indicates that the bonding process is successful to a certain extent and can meet the basic performance requirements of the product.

[0007] The third type: gold-gold layer fracture:

[0008] The fracture occurs between the Bump ball and the substrate pad. The gold-gold bonding process in the USB (Ultrusonic bond) bonding technology is an important link, which mainly relies on the ultrasonic energy output by the bonding tip to achieve. The specific process is that after the ultrasonic energy is output by the bonding tip, it is conducted through the wafer body and finally acts on the Bump, causing vibration between the Bump and the substrate pad. Under the continuous vibration, the friction between the two increases continuously, generating high heat. The high-temperature environment prompts them to re-form molecular bonds, thus realizing the bonding of the gold-gold layer. However, in the actual operation process, there is a significant problem, that is, the energy loss after passing through the wafer is difficult to accurately count. Due to the uncertainty of energy loss, the energy acting between the Bump and the substrate pad during the bonding of the gold-gold layer cannot be accurately controlled, resulting in large fluctuations in the product quality. The quality fluctuations not only affect the consistency and stability of the product, but also increase the defect rate in the production process, raise the production cost, and bring many troubles to the enterprise. Therefore, in order to improve the product quality and ensure the stability and reliability of production, it is necessary to conduct in-depth research and improvement on the existing process, especially for the bonding process of the gold-gold layer, to improve its strength and stability to meet the growing market demand and technical requirements. Summary of the Invention

[0009] In view of the above situation, to overcome the defects of the prior art, the present invention effectively solves the problem that the energy loss during the bonding of the gold-gold layer is difficult to accurately count by optimizing the bonding process and parameters, improves the bonding strength and stability of the gold-gold layer, reduces the product quality fluctuations and defect rate, and enhances the overall quality and reliability of the product.

[0010] To achieve the above object, the following technical solutions are adopted: The present invention provides a new integrated circuit USB bonding process, including the following steps:

[0011] Prepare the substrate pad and the wafer pad;

[0012] Pre-place balls on the upper part of the substrate pad;

[0013] Place balls on the bottom of the wafer pad;

[0014] Bond the substrate pad and the wafer pad. Further, the bonding process can be used for the operation of placing gold balls.

[0015] Further, the bonding process can be carried out by an ultrasonic bonding device.

[0016] The beneficial effects of the present invention are as follows: The present invention improves the bonding method between the original substrate and the solder balls, avoids the defect of insufficient strength after bonding, provides an improvement direction for future process selection, can focus on the bonding area at the same time, reduces the necessity for the substrate factory to consider full gold plating for the pads, thereby reducing the direct material cost and improving the economic benefits. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the novel integrated circuit USB bonding process of the present invention.

[0018] Legend: 1. Substrate pad; 2. Wafer pad; 3. Solder ball; 4. IDT (Interdigital Transducer).

[0019] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. Detailed Embodiments

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0021] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for demonstration purposes and do not limit the content of this application.

[0022] The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The test materials used in the following embodiments are all obtained from commercial channels unless otherwise specified.

[0023] Refer to Figure 1 , an embodiment provided by the present invention: A novel integrated circuit ultrasonic welding bonding process, including the following steps:

[0024] I. Prepare the substrate pad and the wafer pad:

[0025] For the substrate pad, a metal alloy material meeting specific standards is selected, which has good electrical conductivity and thermal conductivity.

[0026] Plasma cleaning is performed before the operation to remove surface oxides and dirt and dust. After the operation, it can be placed in a nitrogen cabinet to prevent the surface of the substrate pad (Pad) from being oxidized or adsorbing new impurities due to the humid environment while waiting for subsequent processes.

[0027] The preparation of the wafer pad is also rigorous. It is first cut from a wafer of specific specifications. The cutting equipment uses high-precision professional cutting instruments and monitors the entire cutting process to ensure cutting accuracy. After cutting, physical grinding can be used as a pretreatment method to make the surface of the wafer pad reach the appropriate roughness to prepare for subsequent ball implantation.

[0028] 2. Pre-planting balls on the upper part of the substrate pad:

[0029] Select solder balls that meet specific material requirements, which have good conductivity and solderability and are suitable for use in integrated circuits. The pre-balling equipment uses a high-precision vacuum balling machine that can accurately control the position of the solder balls.

[0030] Before pre-balling, the gold ball is melted at high temperature by the soldering needle. When planting the ball, the substrate Pad is placed steadily on the workbench of the ball planting machine, and the substrate pad (Pad) is fixed by the vacuum adsorption system so that the soldering needle can accurately identify the working area, and then the gold balls are accurately placed and welded one by one at the predetermined position of the substrate Pad according to the preset position program. The welding method can be ultrasonic welding. After the welding is completed, the substrate Pad is baked to make the solder ball and the substrate Pad initially combined to form a relatively stable pre-balling structure.

[0031] 3. Planting balls on the surface of the wafer pad:

[0032] Solder balls of suitable materials are also selected. In order to enhance the bonding strength between the solder balls and the wafer Pad surface, the wafer Pad surface is subjected to special surface treatment before ball implantation, such as plasma treatment, to enhance the activity of the bottom surface of the wafer Pad.

[0033] The ball is planted using advanced micro-nano ball planting technology, which can achieve extremely high-precision ball planting operations with the help of a high-precision positioning system and a special micro-nano ball planting head. When planting the ball, the wafer pad (Pad) is placed on a dedicated ball planting platform, and the positioning system accurately controls the ball planting head to move to the predetermined position on the wafer pad surface, and then the solder ball is welded to the wafer pad (Pad) surface. After welding, the wafer pad (Pad) is also baked to firmly bond the solder ball to the wafer pad (Pad) to ensure the quality of the ball planting.

[0034] After the chip pad (Pad) ball planting is completed, the chip is cut into individual pieces to form each chip pad (Pad).

[0035] IV. Bond the substrate pad and the wafer pad:

[0036] Pre - ball the upper part of the substrate pad and then clean it. Then bond the substrate pad and the wafer pad.

[0037] Use an improved ultrasonic bonding equipment for bonding. This equipment is equipped with an advanced energy monitoring and feedback system. Before bonding, use the image recognition module on the equipment to align the substrate pad and the wafer pad to ensure that the solder balls on both can accurately contact the corresponding pads. This is the key prerequisite for ensuring the bonding quality.

[0038] During the bonding process, adsorb the wafer through the bonding nozzle, output ultrasonic energy through the bonding nozzle. The energy is conducted through the wafer body to the balls on the wafer and generates high - frequency vibration with the pre - balled balls on the substrate, thereby reforming molecular bonds between the balls on the wafer and the pre - balled balls on the substrate to bond the balls on the wafer and the pre - balled balls on the substrate. After bonding, conduct a comprehensive visual inspection and performance test on the bonded product, including observing the microstructure at the bonding site and testing the electrical performance, etc., to ensure that the product quality meets the requirements.

[0039] V. Result analysis:

[0040] After using the new ball - planting process for GSB (golden studbond) operation: Pre - ball the substrate pad. Through microscopic observation and testing with professional detection equipment, after bonding, the balls on the wafer and the balls on the substrate can be firmly welded. The shape, diameter, and residual gold of the balls meet the specifications, and no abnormalities are found. Subsequently, conduct electrical performance tests on the bonded product, covering multiple aspects such as resistance, capacitance, and signal transmission. The results show that the electrical performance of the product is good.

[0041] After using the new ball - planting process for USB (golden studbond) operation: After bonding, the thrust, ball diameter, residual gold, and ball height all meet the specifications, and no abnormalities are found. Conduct a comprehensive functional test on the USB (golden studbond) interface, including tests on data transfer speed, power supply stability, etc. The test results show that after using the new ball - planting process for USB (golden studbond) operation, the product performance is stable and meets the relevant standard requirements.

[0042] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

[0043] The above description of the present invention and its embodiments is not restrictive. Only one of the embodiments of the present invention is shown in the drawings, and the actual application is not limited thereto. In general, if those of ordinary skill in the art are inspired by it and design similar ways and embodiments without creative efforts without departing from the gist of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A novel integrated circuit ultrasonic welding and bonding process, characterized in that It includes the following steps: Prepare substrate pads and die pads; Pre - ball the upper part of the substrate pads; Ball the bottom of the die pads; Bond the substrate pads and die pads.

2. The novel integrated circuit ultrasonic welding and bonding process according to claim 1, wherein: The bonding process can be used for GSB (golden studbond) operations.

3. The novel integrated circuit ultrasonic welding and bonding process according to claim 1, characterized in that: Pre - balling the upper part of the substrate pads includes pre - balling the upper part of the substrate pads with gold balls.

4. The novel integrated circuit ultrasonic welding and bonding process according to claim 1, characterized in that: Balling the bottom of the die pads includes balling the bottom of the die pads with gold balls.

5. The novel integrated circuit ultrasonic welding and bonding process according to claim 1, wherein: The bonding process can be used for ultrasonic welding operations.

6. The novel integrated circuit ultrasonic welding and bonding process according to claim 1, characterized in that The bonding process is carried out by an ultrasonic bonding device.

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