Laser bonding interconnection process

Abstract

The invention relates to a laser bonding interconnection process, which comprises the following steps of: 1, selecting a substrate and a chip with a certain specification, cleaning the substrate and the chip, and then pre-treating the substrate and the chip; step 2, using a chip absorption and laser emission integrated device with a light-transmitting and high-temperature-resistant material to absorb a chip from the right above, placing an interconnection material between the chip and the substrate as an interconnection layer, and aligning the chip and the substrate to form an interconnection structure of the chip, the interconnection material and the substrate; thirdly, protective gas is introduced, proper laser parameters are selected through the device, pressure and ultrasound are applied, and the welding time is controlled to weld the interconnection structure; and step 4, cooling at room temperature to obtain the interconnection structure. Comprising fine pitch interconnection and chip die bonding, realizes interconnection with better performance, higher efficiency and lower cost, meets advanced packaging requirements, and is used for solving the technical problems.

Description

Technical Field

[0001] The invention relates to the technical field of component packaging interconnection, and in particular to a laser bonding interconnection process. Background Art

[0002] At present, in the field of advanced packaging interconnection, the combination of various components in a single package is becoming more and more important, and the welding method of the packaging structure has a great influence on the reliability of the package. When using the traditional reflow soldering method, the entire "sandwich interconnection structure" needs to be in a high temperature welding environment, which may affect the performance and reliability of the product; at the same time, the operation of the reflow oven is relatively complicated. If the welding parameters and temperature zones are not set properly, it is easy to cause welding defects such as cold welding, false welding, and bridging.

[0003] To improve the shortcomings of reflow soldering, hot pressing sintering is currently used for soldering. However, this method has a long heating and cooling time period during the entire soldering process, which will reduce production efficiency, resulting in low UPH and high cost. Therefore, it is difficult to meet the requirements of advanced packaging using traditional soldering methods. Summary of the invention

[0004] In view of the above-mentioned defects, the purpose of the present invention is to propose a laser bonding interconnection process, including fine pitch interconnection and chip bonding, while achieving better performance, higher efficiency and lower cost interconnection, meeting advanced packaging requirements, and solving the above-mentioned technical problems.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A laser bonding interconnection process comprises the following steps:

[0007] Step 1, selecting a substrate and a chip of a certain specification, and cleaning the substrate and the chip and performing pretreatment;

[0008] Step 2: Use a chip suction and laser emission integrated device with a light-transmitting and high-temperature resistant material to suck the chip from the top, place the interconnection material between the chip and the substrate as an interconnection layer, align the chip and the substrate to form an interconnection structure of the chip, the interconnection material, and the substrate;

[0009] Step 3, introducing a protective gas, using the device to select appropriate laser parameters, applying pressure and ultrasound, and controlling the welding time to weld the interconnection structure;

[0010] Step 4: Cooling at room temperature to obtain the interconnection structure.

[0011] Preferably, in step 1, the size of the chip and the substrate is 1 μm-300 mm, wherein the pitch of the chip is 1 μm-200 μm; and the pretreatment includes using one or more of SAM, acid treatment and plasma treatment.

[0012] Preferably, in step 2, the light-transmitting, high-temperature-resistant material includes one of quartz glass, transparent fiberglass, and yttrium oxide transparent ceramics.

[0013] Preferably, in step 2, the laser light source of the integrated chip absorption and laser emission device includes one of a CO2 laser, a Nd:YAG laser, a fiber laser, and a semiconductor laser.

[0014] Furthermore, in step 2, the interconnection material includes nano-metal slurries such as gold, silver, copper, tin, and various alloy nano-materials such as silver / copper, gold / tin, tin / silver, and one or more of solder paste, die-bonding glue, and conductive glue.

[0015] Furthermore, in step 2, the interconnect material placement method includes one of dipping, screen printing, and direct deposition.

[0016] Furthermore, in step three, the protective gas includes one or more of air, nitrogen, argon, and helium.

[0017] Furthermore, in step three, the laser parameters include a laser power of 1-3000 W and a laser wavelength of 0.7-10.6 μm.

[0018] Furthermore, in step three, the pressure is 0-40 MPa, the ultrasonic driving frequency is 0-100 kHz, and the welding time is 1-3600 s.

[0019] One of the above technical solutions includes the following beneficial effects: the present invention completes the interconnection process between the chip and the substrate by laser bonding, selects a substrate and a chip of a certain specification, and cleans the substrate and the chip and performs pretreatment; uses a chip suction and laser emission integrated device with a light-transmitting and high-temperature resistant material to suck the chip from the top, and places the interconnection material between the chip and the substrate as an interconnection layer, aligns the chip and the substrate, so as to form an interconnection structure of the chip, the interconnection material, and the substrate; introduces a protective gas, uses the device to select appropriate laser parameters, and applies pressure and ultrasound, controls the welding time to weld the interconnection structure; and obtains the interconnection structure after cooling at room temperature. The present invention uses chip suction and laser bonding integration to reduce the process of alignment of the laser spot and the solder joint during the laser bonding process, and can also greatly reduce the heating and cooling time period of the entire chip bonding process, thereby reducing the cost in the chip bonding process and realizing a significant improvement in the efficiency of the chip bonding process, achieving the effect of improving chip packaging efficiency and quality. This new chip interconnection process can achieve more efficient and reliable chip interconnection, and can meet the requirements of advanced packaging interconnection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A method flow chart of a laser bonding interconnection process of the present invention;

[0021] Figure 2 Schematic diagram of laser bonding applied to ultra-fine pitch all-copper interconnection process of flip chip;

[0022] Figure 3 Schematic diagram of laser bonding application in chip die attach process. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0024] like Figure 1-3 As shown, a laser bonding interconnection process is characterized by comprising the following steps:

[0025] Step 1, selecting a substrate and a chip of a certain specification, and cleaning the substrate and the chip and performing pretreatment;

[0026] Step 2: Use a chip suction and laser emission integrated device with a light-transmitting and high-temperature resistant material to suck the chip from the top, place the interconnection material between the chip and the substrate as an interconnection layer, align the chip and the substrate to form an interconnection structure of the chip, the interconnection material, and the substrate;

[0027] Step 3, introducing a protective gas, using the device to select appropriate laser parameters, applying pressure and ultrasound, and controlling the welding time to weld the interconnection structure;

[0028] Step 4: Cooling at room temperature to obtain the interconnection structure.

[0029] The present invention completes the interconnection process between the chip and the substrate through laser bonding, selects a substrate and a chip of a certain specification, and cleans the substrate and the chip and performs pretreatment; uses a chip suction and laser emission integrated device with a light-transmitting and high-temperature resistant material to suck the chip from the top, and places the interconnection material between the chip and the substrate as an interconnection layer, aligns the chip and the substrate, so that it forms an interconnection structure of the chip, the interconnection material, and the substrate; introduces a protective gas, uses the device to select appropriate laser parameters, and applies pressure and ultrasound, controls the welding time to weld the interconnection structure; and obtains the interconnection structure after cooling at room temperature. The present invention uses chip suction and laser bonding integration to reduce the process of alignment between the laser spot and the solder joint during the laser bonding process, and can also greatly reduce the heating and cooling time period of the entire chip bonding process, thereby reducing the cost in the chip bonding process and realizing a significant improvement in the efficiency of the chip bonding process, achieving the effect of improving chip packaging efficiency and quality. This new chip interconnection process can achieve more efficient and reliable chip interconnection, and can meet the requirements of advanced packaging interconnection.

[0030] Wherein, in step 1, the size of the chip and the substrate is 1 μm-300 mm, wherein the pitch of the chip is 1 μm-200 μm; and the pretreatment includes using one or more of SAM, acid treatment and plasma treatment.

[0031] This method can be used on chips and substrates in a larger size range and has a wide range of applications; and the pretreatment can clean the surface of the chip and substrate to remove impurities.

[0032] Among them, in step 2, the light-transmitting, high-temperature resistant material includes one of quartz glass, transparent fiberglass, and yttrium oxide transparent ceramic.

[0033] This method is highly applicable to a variety of light-transmitting and high-temperature resistant materials, and can meet normal use under various conditions and scenarios.

[0034] Wherein, in step 2, the laser light source of the chip absorption and laser emission integrated device includes one of a CO2 laser, a Nd:YAG laser, a fiber laser, and a semiconductor laser.

[0035] This method can be used under a variety of laser light sources, so that different materials can choose a more suitable laser light source to form a more adapted effect, thereby obtaining better performance.

[0036] In addition, in step 2, the interconnection material includes nano-metal slurries such as gold, silver, copper, tin, and various alloy nano-materials such as silver / copper, gold / tin, tin / silver, and one or more of solder paste, die-bonding glue, and conductive glue.

[0037] This method has a wide range of material applications and can meet the use of a variety of materials.

[0038] In addition, in step 2, the interconnect material placement method includes one of dipping, screen printing, and direct deposition.

[0039] In addition, in step three, the protective gas includes one or more of air, nitrogen, argon, and helium.

[0040] This method can be used in an air atmosphere, which reduces the use of protective gas, expands the scope of application and reduces costs; at the same time, it also meets the requirements of normal use under protective gas.

[0041] In addition, in step three, the laser parameters include a laser power of 1-3000W and a laser wavelength of 0.7-10.6μm.

[0042] This method can be used in a larger laser power range and a wider laser wavelength range, and can better meet the requirements of different materials for laser power and wavelength, thereby expanding the application scope of the method.

[0043] In addition, in step three, the pressure is 0-40 MPa, the ultrasonic driving frequency is 0-100 kHz, and the welding time is 1-3600 s.

[0044] This method can be used under pressure and ultrasonic drive, and can also be used without pressure and ultrasonic drive, and has a better application range; this method can complete sintering in a very short time, achieving the effect of saving time and cost.

[0045] Example 1

[0046] The present invention provides a laser bonding interconnection process, comprising the following steps:

[0047] Step 1, select a chip and a substrate with a copper pillar diameter of 40 μm, a copper pillar spacing of 40 μm, 10 copper pillar bumps, and a size of 2 mm*2 mm and 3 mm*3 mm, and clean the substrate and the chip and then perform pretreatment by ultrasonic cleaning with dilute sulfuric acid;

[0048] Step 2: placing the copper nano-slurry between the chip and the substrate as an interconnection layer by dipping, so as to form an interconnection structure of chip-copper nano-slurry-substrate;

[0049] Step 3, introducing nitrogen, using a laser welding machine with a Nd:YAG laser, setting the laser power to 16 W, the laser wavelength to 1.06 μm, applying a pressure of 4 MPa, an ultrasonic drive of 0 kHz, controlling the welding time to 7 s, and then welding the interconnection structure;

[0050] Step 4: After cooling at room temperature, a flip-chip interconnection structure is obtained. The overall shear strength is 33.2 MPa obtained by shearing with a push-pull testing machine, and the resistivity is 9.1 μΩ·cm measured by a four-point probe method.

[0051] Example 2

[0052] The present invention provides a laser bonding interconnection process, comprising the following steps:

[0053] Step 1, select a chip and a substrate with a copper pillar diameter of 60 μm, a copper pillar spacing of 60 μm, 12 copper pillar bumps, and a size of 3 mm*3 mm and 4 mm*4 mm, and clean the substrate and the chip and then perform pretreatment by ultrasonic cleaning with dilute sulfuric acid;

[0054] Step 2: placing the copper nano-slurry between the chip and the substrate as an interconnection layer by dipping, so as to form an interconnection structure of chip-copper nano-slurry-substrate;

[0055] Step three, step three, introduce nitrogen, use a laser welding machine with a fiber laser, set the laser power to 14W, the laser wavelength to 0.97μm, apply 4MPa pressure, 0kHz ultrasonic drive, control the welding time to 9s, and weld the interconnection structure;

[0056] Step 4: After cooling at room temperature, a flip-chip interconnection structure is obtained. The overall shear strength is 37.2 MPa obtained by shearing with a push-pull testing machine, and the resistivity is 6.4 μΩ·cm measured by a four-point probe method.

[0057] Example 3

[0058] The present invention provides a laser bonding interconnection process, comprising the following steps:

[0059] Step 1, selecting a chip with a size of 3mm*3mm and a substrate with a size of 5mm*5mm, and cleaning the substrate and the chip and then pre-treating them with plasma cleaning;

[0060] Step 2: Place solder paste between the chip and the substrate as an interconnection layer by screen printing to form an interconnection structure of chip-solder paste-substrate;

[0061] Step 3, using a laser welding machine with a Nd:YAG laser, setting the laser power to 14 W, the laser wavelength to 1.06 μm, applying a pressure of 1 MPa, a 30 kHz ultrasonic drive, and controlling the welding time to 4 s, to weld the interconnection structure;

[0062] Step 4: After cooling at room temperature, a chip die-bonding structure with solder paste as the interconnection material is obtained. The overall shear strength is 36.7 MPa obtained by shearing with a push-pull test machine, and the resistivity is 15.3 μΩ·cm measured by a four-point probe method.

[0063] Example 4

[0064] The present invention provides a laser bonding interconnection process, comprising the following steps:

[0065] Step 1, selecting a chip with a size of 10 mm*10 mm and a substrate with a size of 15 mm*15 mm, and cleaning the substrate and the chip and then pre-treating them with plasma cleaning;

[0066] Step 2: Place solder paste between the chip and the substrate as an interconnection layer by screen printing to form an interconnection structure of chip-solder paste-substrate;

[0067] Step 3, using a laser welding machine with a fiber laser, setting the laser power to 12 W, the laser wavelength to 0.97 μm, applying a pressure of 1 MPa, a 30 kHz ultrasonic drive, and controlling the welding time to 6 s, to weld the interconnection structure;

[0068] Step 4: After cooling at room temperature, a chip die-bonding structure with solder paste as the interconnection material is obtained. The overall shear strength is 38.1 MPa obtained by shearing with a push-pull test machine, and the resistivity is 14.5 μΩ·cm measured by a four-point probe method.

[0069] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A laser bonding interconnection process, characterized in that: The following steps are involved: Step 1, selecting a substrate and a chip of a certain specification, and cleaning the substrate and the chip and performing pretreatment; Step 2: Use a chip suction and laser emission integrated device with a light-transmitting and high-temperature resistant material to suck the chip from the top, place the interconnection material between the chip and the substrate as an interconnection layer, align the chip and the substrate to form an interconnection structure of the chip, the interconnection material, and the substrate; Step 3, introducing a protective gas, using the device to select appropriate laser parameters, applying pressure and ultrasound, and controlling the welding time to weld the interconnection structure; Step 4: Cooling at room temperature to obtain the interconnection structure.

2. The laser bonding interconnection process according to claim 1, characterized in that: In step 1, the size of the chip and the substrate is 1 μm-300 mm, wherein the pitch of the chip is 1 μm-200 μm; the pretreatment includes using one or more of SAM, acid treatment and plasma treatment.

3. The laser bonding interconnection process according to claim 1, characterized in that: In step 2, the light-transmitting, high-temperature-resistant material includes one of quartz glass, transparent fiberglass, and yttrium oxide transparent ceramic.

4. The laser bonding interconnection process according to claim 1, characterized in that: In step 2, the laser light source of the chip absorption and laser emission integrated device includes one of a CO2 laser, a Nd:YAG laser, a fiber laser, and a semiconductor laser.

5. The laser bonding interconnection process according to claim 1, characterized in that: In step 2, the interconnection material includes nano-metal slurries such as gold, silver, copper, tin, and various alloy nano-materials such as silver / copper, gold / tin, tin / silver, and one or more of solder paste, die-bonding glue, and conductive glue.

6. The laser bonding interconnection process according to claim 1, characterized in that: In step 2, the interconnect material placement method includes one of dipping, screen printing, and direct deposition.

7. The laser bonding interconnection process according to claim 1, characterized in that: In step three, the protective gas includes one or more of air, nitrogen, argon, and helium.

8. The laser bonding interconnection process according to claim 1, characterized in that: In step three, the laser parameters include a laser power of 1-3000W and a laser wavelength of 0.7-10.6μm.

9. The laser bonding interconnection process according to claim 1, characterized in that: In step three, the pressure is 0-40 MPa, the ultrasonic driving frequency is 0-100 kHz, and the welding time is 1-3600 s.

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