Adirectional laser sintering interconnection process

Abstract

The invention discloses a non-directional laser sintering interconnection process, which comprises the following steps of: 1, selecting a substrate and a chip which are matched with each other, cleaning the substrate and the chip, and then pre-treating the substrate and the chip; 2, placing an interconnection material between the chip and the substrate as an interconnection layer to form an interconnection structure of the chip, the interconnection material and the substrate; thirdly, protective gas is introduced, a laser welding machine is used for selecting proper laser parameters, the irradiation direction of a laser beam is set, pressure and ultrasound are applied at the same time, and the welding time is controlled to weld the interconnection structure; and step 4, cooling at room temperature to obtain the interconnection structure. The non-directional laser sintering interconnection process comprises fine pitch interconnection and chip die bonding, can reduce the occurrence of a substrate warping phenomenon, meets advanced packaging requirements, and is used for solving the technical problems.

Description

Technical Field

[0001] The invention relates to a component packaging interconnection technology, in particular to a non-directional laser sintering interconnection process. Background Art

[0002] At present, in the field of advanced semiconductor and microelectronic packaging, the combination of various electronic components in a single package is becoming more and more important. When using traditional reflow soldering and hot pressing soldering, the entire "sandwich interconnect structure" will be in the high temperature heat affected zone for a long time, causing the substrate to warp, affecting the normal use of the substrate. When the substrate warps severely, it will cause the substrate to crack, resulting in package failure.

[0003] Currently, there is a way to improve the substrate warping problem by thickening the substrate, but this method will reduce the heat dissipation performance of the substrate, and the reduction of heat dissipation performance will cause the chip to be in a high temperature state for a long time and cause damage to it, seriously affecting the service life of the chip. Therefore, it is urgent to improve the substrate warping problem. Summary of the invention

[0004] In view of the above defects, the purpose of the present invention is to propose a non-directional laser sintering interconnection process, including fine pitch interconnection and chip bonding, which can reduce the occurrence of substrate warping, meet advanced packaging requirements, and solve the above technical problems.

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

[0006] A non-directional laser sintering interconnection process comprises the following steps:

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

[0008] Step 2: placing an interconnection material between the chip and the substrate as an interconnection layer to form an interconnection structure of the chip, the interconnection material and the substrate;

[0009] Step 3, introducing a protective gas, using a laser welding machine to select appropriate laser parameters, and setting the irradiation direction of the laser beam, while 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-500 mm; and the pretreatment includes one or more of acid treatment, plasma treatment and SAM.

[0012] Preferably, the interconnection material in step 2 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.

[0013] Preferably, the interconnect material placement method in step 2 includes one of direct deposition, screen printing, and dipping.

[0014] Furthermore, the protective gas in step three includes one or more of air, helium, argon and nitrogen.

[0015] Furthermore, the laser light source of the laser welding machine in step three includes one of a CO2 laser, a fiber laser, a semiconductor laser, and a Nd:YAG laser.

[0016] Furthermore, the laser parameters in step three include a laser power of 1-1000W and a laser wavelength of 0.1-13μm.

[0017] Furthermore, the irradiation direction of the laser beam in step three is any direction around the interconnection structure.

[0018] Furthermore, in step three, the pressure is 0-60 MPa, the ultrasonic driving frequency is 0-200 kHz, and the welding time is 1-7200 s.

[0019] Furthermore, the process uses a rotary welding stage and a six-degree-of-freedom manipulator, the laser of the laser welding machine is installed at the execution end of the six-degree-of-freedom manipulator, and the rotary welding stage is used to place the substrate;

[0020] The rotary welding platform is located within the working range of the six-degree-of-freedom manipulator.

[0021] 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 welding, selects a substrate and a chip of a certain specification, and cleans the substrate and the chip and performs pretreatment; places the interconnection material on the chip and the substrate as an interconnection layer to form an interconnection structure of chip-interconnection material-substrate; introduces a protective gas, uses a laser welding machine to select appropriate laser parameters and laser irradiation direction, and applies pressure, ultrasound and controls the welding time to weld the interconnection structure; and obtains the interconnection structure after cooling at room temperature. The present invention uses the thermal radiation of a non-directional laser beam for sintering to optimize the welding process and reduce the high thermomechanical stress during the welding process, thereby significantly reducing the warping phenomenon of the substrate, enhancing the stability and reliability of the chip interconnection, and achieving the effect of reducing the use cost and increasing the service life of the substrate and the chip. The present invention designs a new chip interconnection process, which can achieve more stable chip interconnection and meet the requirements of advanced packaging interconnection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a method flow chart of a non-directional laser sintering interconnection process of the present invention;

[0023] Figure 2 It is a schematic diagram of the application of non-directional laser sintering in the flip chip interconnection process;

[0024] Figure 3 Schematic diagram of the application of non-directional laser sintering in chip bonding process. DETAILED DESCRIPTION

[0025] 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.

[0026] like Figure 1-3 As shown, a non-directional laser sintering interconnection process includes the following steps:

[0027] Step 1, selecting a suitable substrate and chip, and cleaning the substrate and chip and performing pretreatment;

[0028] Step 2: placing an interconnection material between the chip and the substrate as an interconnection layer to form an interconnection structure of the chip, the interconnection material and the substrate;

[0029] Step 3, introducing a protective gas, using a laser welding machine to select appropriate laser parameters, and setting the irradiation direction of the laser beam, while applying pressure and ultrasound and controlling the welding time to weld the interconnection structure;

[0030] Step 4: Cooling at room temperature to obtain the interconnection structure.

[0031] The present invention completes the interconnection process between the chip and the substrate through laser welding, selects a substrate and a chip of a certain specification, and cleans the substrate and the chip and performs pretreatment; places the interconnection material on the chip and the substrate as an interconnection layer to form an interconnection structure of chip-interconnection material-substrate; introduces a protective gas, uses a laser welding machine to select appropriate laser parameters and laser irradiation direction, and applies pressure, ultrasound and controls the welding time to weld the interconnection structure; and obtains the interconnection structure after cooling at room temperature. The present invention uses the thermal radiation of a non-directional laser beam for sintering to optimize the welding process and reduce the high thermomechanical stress during the welding process, thereby significantly reducing the warping of the substrate, enhancing the stability and reliability of the chip interconnection, and achieving the effect of reducing the use cost and increasing the service life of the substrate and chip. The present invention designs a new chip interconnection process that can achieve more stable chip interconnection and meet the requirements of advanced packaging interconnection.

[0032] Wherein, in step 1, the size of the chip and the substrate is 1 μm-500 mm; the pretreatment includes one or more of acid treatment, plasma treatment and SAM.

[0033] 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.

[0034] Among them, the interconnection material in step 2 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, solid crystal glue, and conductive glue.

[0035] It has a wide range of material applications and can meet the use of a variety of materials.

[0036] Wherein, the interconnect material placement method in step 2 includes one of direct deposition, screen printing, and dipping.

[0037] It can meet the use of various interconnect material placement methods and expand the scope of application.

[0038] In addition, the protective gas in step three includes one or more of air, helium, argon, and nitrogen.

[0039] It can be used in 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 normal use under protective gas.

[0040] In addition, the laser light source of the laser welding machine in step three includes one of a CO2 laser, a fiber laser, a semiconductor laser, and a Nd:YAG laser.

[0041] 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.

[0042] In addition, the laser parameters in step three include a laser power of 1-1000W and a laser wavelength of 0.1-13μm.

[0043] 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.

[0044] In addition, the irradiation direction of the laser beam in step three is any direction around the interconnection structure.

[0045] The non-directional irradiation of laser beams can better meet the use in multiple application scenarios. When the traditional method makes it difficult to achieve laser beam irradiation in a certain direction or on a certain surface, the method of using non-directional irradiation of laser beams in all directions will be more advantageous.

[0046] In addition, the pressure in step three is 0-60MPa, the ultrasonic driving frequency is 0-200kHz, and the welding time is 1-7200s.

[0047] 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.

[0048] In addition, the process uses a rotary welding stage and a six-degree-of-freedom manipulator, the laser of the laser welding machine is installed at the execution end of the six-degree-of-freedom manipulator, and the rotary welding stage is used to place the substrate;

[0049] The rotary welding platform is located within the working range of the six-degree-of-freedom manipulator.

[0050] Example 1

[0051] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0052] Step 1, selecting a chip and a substrate with a copper pillar diameter of 50 μm, a copper pillar spacing of 50 μm, and 10 copper pillar bumps, and cleaning the substrate and the chip and then performing pretreatment by ultrasonic cleaning with dilute sulfuric acid;

[0053] 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;

[0054] Step 3, introducing nitrogen, using a laser welding machine with a Nd:YAG laser, setting the laser power to 15 W, the laser wavelength to 1.06 μm, applying a pressure of 3 MPa, an ultrasonic drive of 0 kHz, controlling the welding time to 8 s, and then welding the interconnection structure;

[0055] Step 4: After cooling at room temperature, a flip-chip interconnection structure is obtained. The overall shear strength is 34.6 MPa obtained by shearing with a push-pull test machine. The resistivity is 7.3 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0056] Example 2

[0057] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0058] Step 1, selecting a chip and a substrate with a copper pillar diameter of 50 μm, a copper pillar spacing of 50 μm, and 10 copper pillar bumps, and cleaning the substrate and the chip and then performing pretreatment by ultrasonic cleaning with dilute sulfuric acid;

[0059] 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;

[0060] Step three, step three, introduce nitrogen, use a laser welding machine with a fiber laser, set the laser power to 18W, the laser wavelength to 0.97μm, apply 3MPa pressure, 0kHz ultrasonic drive, control the welding time to 6s, and weld the interconnection structure;

[0061] Step 4: After cooling at room temperature, a flip-chip interconnection structure is obtained. The overall shear strength is 36.3 MPa obtained by shearing with a push-pull test machine. The resistivity is 8.4 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0062] Example 3

[0063] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0064] Step 1, selecting a chip with a size of 5 mm and a substrate with a size of 8 mm, and cleaning the substrate and the chip and then pre-treating them with plasma cleaning;

[0065] 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;

[0066] Step 3, using a laser welding machine with a Nd:YAG laser, setting the laser power to 12 W, the laser wavelength to 1.06 μm, applying a pressure of 2 MPa, a 20 kHz ultrasonic drive, and controlling the welding time to 4 s, to weld the interconnection structure;

[0067] Step 4: After cooling at room temperature, a chip solid crystal structure with solder paste as the interconnection material is obtained. The overall shear strength is 38.4 MPa obtained by shearing with a push-pull test machine. The resistivity is 13.4 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0068] Example 4

[0069] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0070] Step 1, selecting a chip with a size of 5 mm and a substrate with a size of 8 mm, and cleaning the substrate and the chip and then pre-treating them with plasma cleaning;

[0071] 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;

[0072] Step 3, using a laser welding machine with a fiber laser, setting the laser power to 10 W, the laser wavelength to 0.97 μm, applying a pressure of 2 MPa, an ultrasonic drive of 20 kHz, and controlling the welding time to 6 s, to weld the interconnection structure;

[0073] Step 4: After cooling at room temperature, a chip solid crystal structure with solder paste as the interconnection material is obtained. The overall shear strength is 40.3 MPa obtained by shearing with a push-pull test machine. The resistivity is 12.1 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0074] 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 non-directional laser sintering interconnection process, characterized in that: The following steps are involved: Step 1, selecting a suitable substrate and chip, and cleaning the substrate and chip and performing pretreatment; Step 2: placing an interconnection material between the chip and the substrate as an interconnection layer to form an interconnection structure of the chip, the interconnection material and the substrate; Step 3, introducing a protective gas, using a laser welding machine to select appropriate laser parameters, and setting the irradiation direction of the laser beam, while 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 non-directional laser sintering interconnection process according to claim 1, characterized in that: In step 1, the size of the chip and the substrate is 1 μm-500 mm; the pretreatment includes one or more of acid treatment and plasma treatment.

3. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The interconnection material in step 2 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.

4. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The interconnect material placement method in step 2 includes direct deposition, screen printing, and dipping.

5. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The protective gas in step three includes one or more of air, helium, argon and nitrogen.

6. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The laser light source of the laser welding machine in step three includes one of a CO2 laser, a fiber laser, a semiconductor laser, and a Nd:YAG laser.

7. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The laser parameters in step three include a laser power of 1-1000W and a laser wavelength of 0.1-13μm.

8. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The irradiation direction of the laser beam in step three is any direction around the interconnection structure.

9. The non-directional laser sintering interconnection process according to claim 1, characterized in that: In step three, the pressure is 0-60 MPa, the ultrasonic driving frequency is 0-200 kHz, and the welding time is 1-7200 s.

10. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The process uses a rotary welding platform and a six-degree-of-freedom manipulator. The laser of the laser welding machine is installed at the execution end of the six-degree-of-freedom manipulator, and the rotary welding platform is used to place the substrate. The rotary welding platform is located within the working range of the six-degree-of-freedom manipulator.

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