Ceramic chopper, preparation method thereof and application of ceramic chopper in thermal ultrasonic bonding packaging of semiconductor integrated circuit

Abstract

The invention belongs to the technical field of bonding chopper and preparation thereof, and particularly relates to a ceramic chopper, a preparation method thereof and application of the ceramic chopper in thermal ultrasonic bonding packaging of a semiconductor integrated circuit. The ceramic chopper provided by the invention is prepared by taking aluminum oxide as a matrix and matching silicon carbide nanofiber, magnesium oxide and yttrium oxide in a certain proportion through ball milling, granulation, molding and high-temperature sintering processes, has the broadband ultrasonic transmission capability of 20-135kHz, and has the maximum amplitude of 3.8 mu m. Experiments show that the chopper can shorten the bonding time by 25%, increase the qualified rate to 99%, increase the shear strength by 20%, and significantly improve the bonding efficiency and reliability. The ceramic chopper disclosed by the invention can well meet the requirements of thermal ultrasonic bonding packaging of a semiconductor integrated circuit on high energy efficiency and high precision bonding, and has a wide industrial application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of bonding capillary and its preparation, and particularly relates to a ceramic capillary, a preparation method thereof, and an application in the thermo - ultrasonic bonding and packaging of semiconductor integrated circuits. Background Art

[0002] The thermo - ultrasonic bonding and packaging of semiconductor integrated circuits is one of the core processes for realizing the electrical connection between chips and external circuits. In this process, ultrasonic energy is transmitted to the contact interface between the metal wire (gold wire / copper wire) and the chip through a ceramic capillary, and high - frequency vibration (usually 20 - 75 kHz) is used to break the interface oxide layer and promote atomic bonding. With the development of semiconductor devices towards high density and high reliability, the bonding process has put forward higher requirements for the ultrasonic energy transmission efficiency.

[0003] However, the performance bottleneck of traditional ceramic capillaries in this process is becoming increasingly prominent. Currently, the mainstream ceramic capillary materials are mainly alumina (Al2O3) - based ceramics, which have obvious limitations in mechanical properties and ultrasonic wave - guiding characteristics. They face multiple technical challenges in the thermo - ultrasonic bonding and packaging of semiconductor integrated circuits: due to the limitation of acoustic impedance matching characteristics in their material systems, the effective ultrasonic transmission frequency band usually only covers 20 - 60 kHz, making it difficult to meet the requirements of increasingly advanced packaging processes for high - frequency wide - band; at the same time, the relatively high mechanical loss factor of the material leads to serious attenuation of ultrasonic energy, and the maximum amplitude is generally lower than 2.5 μm; in addition, the rigid alumina matrix is prone to stress concentration under high - frequency vibration, significantly increasing the probability of forming micro - cracks at the bonding interface, affecting the packaging reliability and also the service life of the bonding capillary.

[0004] In recent years, researchers have tried to improve the performance of ceramic capillaries through material modification. Among them, the zirconia toughening technology can improve the fracture toughness of the material, but it will reduce the sound speed and increase the energy loss, resulting in a decline in high - frequency response ability; although carbon nanotube reinforcement can improve the strength of the material, it is easy to cause interface defects and affect the uniformity of ultrasonic transmission; the design of functionally graded materials can improve the stress distribution through gradual composition change, but the process is complex and the cost is high. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a ceramic capillary, a preparation method thereof, and an application in the thermo - ultrasonic bonding and packaging of semiconductor integrated circuits.

[0006] The purpose of the present invention is to provide an economical ceramic capillary with broadband ultrasonic transmission ability and high - amplitude characteristics to improve the efficiency and quality of thermo - ultrasonic bonding of semiconductor integrated circuits.

[0007] The first aspect of the present invention is to provide a ceramic capillary. The mixed raw materials for preparing the ceramic capillary include the following components by mass percentage:

[0008] Aluminum oxide: 80 - 90%;

[0009] Magnesium oxide: 3 - 5%;

[0010] Yttrium oxide: 2 - 4%;

[0011] Silicon carbide nanofibers: 3 - 12%;

[0012] The ceramic capillary is prepared by molding and sintering the mixed raw materials.

[0013] As a further optimized solution for the composition of the ceramic capillary, the mixed raw materials include the following components by mass percentage:

[0014] Aluminum oxide: 80 - 90%;

[0015] Magnesium oxide: 3 - 5%;

[0016] Yttrium oxide: 2 - 4%;

[0017] Silicon carbide nanofibers: 6 ± 0.5%.

[0018] As a further optimized solution for the composition of the ceramic capillary, the mixed raw materials include the following components by mass percentage:

[0019] Aluminum oxide: 87 ± 1%;

[0020] Magnesium oxide: 4 ± 0.5%;

[0021] Yttrium oxide: 3 ± 0.5%;

[0022] Silicon carbide nanofibers: 6 ± 0.5%.

[0023] Preferably, the effective ultrasonic transmission frequency band of the sintered ceramic capillary is 20 - 135 kHz, and the maximum amplitude ≥ 3.5 μm.

[0024] The second aspect of the present invention is to provide a method for preparing a ceramic capillary, including the following steps:

[0025] Step S1: Prepare silicon carbide nanofibers;

[0026] Step S2: Mix and ball-mill aluminum oxide, magnesium oxide, yttrium oxide and silicon carbide nanofibers according to a predetermined mass percentage to obtain mixed raw materials;

[0027] Step S3: Spray granulate the mixed raw materials obtained after ball-milling to obtain powder particles;

[0028] Step S4: Mold the powder particles obtained by granulation to obtain a green body;

[0029] Step S5: High-temperature sinter the molded green body under a protective atmosphere to obtain a ceramic capillary.

[0030] As a further optimized solution for the preparation method of the ceramic split knife, in step S1, the preparation of silicon carbide nanofibers includes the following steps:

[0031] (a) Add polycarbosilane and xylene into a reaction vessel and stir to dissolve;

[0032] (b) Add a platinum dichloride catalyst and react at 170 - 185 °C for 4 - 8 hours;

[0033] (c) Heat the reaction product in a heating furnace to 950 - 1050 °C and keep it warm for 1.5 - 3 hours for pyrolysis;

[0034] (d) Further heat it to 1550 - 1650 °C and keep it warm for 3 - 5 hours for carbothermal reduction to obtain silicon carbide nanofibers.

[0035] As a further optimized solution for the preparation method of the ceramic split knife, in step S2, the materials are ball - milled in a planetary ball mill for 18 - 30 hours to obtain a mixed raw material.

[0036] As a further optimized solution for the preparation method of the ceramic split knife, in step S3, the mixed raw material obtained after ball - milling is transported to a centrifugal spray drying tower for spray granulation to obtain powder particles.

[0037] As a further optimized solution for the preparation method of the ceramic split knife, in step S4, the compaction pressure is 150 - 250 MPa.

[0038] As a further optimized solution for the preparation method of the ceramic split knife, in step S5, the sintering temperature is 1700 - 1800 °C and the sintering time is 3 - 5 hours.

[0039] As a further optimized solution for the preparation method of the ceramic split knife, in step S5, the sintering atmosphere is preferably argon, and the purity of argon is preferably not less than 99.99%.

[0040] The third aspect of the present invention is to provide an application of the ceramic split knife. The above - mentioned ceramic split knife is applied to the thermosonic bonding and encapsulation of semiconductor integrated circuit chips. During the bonding process, the ceramic split knife transfers ultrasonic energy to the contact interface between the metal wire and the chip, promotes the atomic - level bonding of the contact interface, and realizes the electrical connection between the chip and the external circuit.

[0041] Beneficial effects

[0042] The alumina-based ceramic bonding tool provided by the present invention significantly broadens the effective transmission frequency band of ultrasonic waves (up to 20 - 135 kHz), and at the same time increases the maximum amplitude to 3.8 microns, having excellent high-frequency response performance and energy transfer efficiency. In actual bonding applications, the ceramic bonding tool provided by the present invention can significantly shorten the bonding time, improve the bonding qualification rate and shear strength, effectively reduce the generation of microcracks, and better meet the stringent technical requirements of the semiconductor integrated circuit thermosonic bonding process for high-frequency wideband and high-energy efficiency transmission. Detailed implementation manners

[0043] The present invention will be further illustrated by specific examples below. These examples are exemplary, aiming to illustrate the problem and explain the present invention, rather than a limitation.

[0044] Example 1

[0045] (1) Preparation of silicon carbide nanofibers

[0046] Add 100 g of polycarbosilane and 400 ml of xylene into a 500 ml three-necked flask, stir and dissolve. Add 2.5 g of platinum dichloride catalyst, and reflux and react in an oil bath at 180 °C for 6 hours. Place the reaction product in a tubular furnace, heat it to 1000 °C at a rate of 5 °C / min, and keep it at this temperature for 2 hours for pyrolysis. Then heat it to 1600 °C at a rate of 10 °C / min and keep it at this temperature for 4 hours for carbothermal reduction to obtain silicon carbide nanofibers.

[0047] (2) Preparation of the ceramic bonding tool

[0048] Weigh and mix 87% alumina, 4% magnesia, 3% yttria, and 6% silicon carbide nanofibers according to mass percentage, and ball mill them in a planetary ball mill for 24 hours. Use an LPG-5 spray drying tower for spray granulation. Dry press and form at a pressure of 200 MPa using a YH32-315T hydraulic press. Put it into a KSL-1700X high-temperature furnace, heat it to 1750 °C at a rate of 5 °C / min, and keep it in an argon atmosphere for 4 hours for sintering. After cooling, the finished ceramic bonding tool is obtained.

[0049] Example 2

[0050] (1) Preparation of silicon carbide nanofibers

[0051] Add 100 g of polycarbosilane and 400 ml of xylene into a 500 ml three-necked flask, stir and dissolve. Add 2.5 g of platinum dichloride catalyst, and reflux and react in an oil bath at 180 °C for 6 hours. Place the reaction product in a tubular furnace, heat it to 1000 °C at a rate of 5 °C / min, and keep it at this temperature for 2 hours for pyrolysis. Then heat it to 1600 °C at a rate of 10 °C / min and keep it at this temperature for 4 hours for carbothermal reduction to obtain silicon carbide nanofibers.

[0052] (2) Preparation of Ceramic Bonding Tools

[0053] Weighing by mass percentage, proportionally mix 89.77% alumina, 4.13% magnesia, 3.10% yttria, and 3% silicon carbide nanofibers, and ball mill in a planetary ball mill for 24 hours. Use an LPG-5 spray drying tower for spray granulation. Dry press and form under a pressure of 200 MPa using a YH32-315T hydraulic press. Place it in a KSL-1700X high-temperature furnace, heat it up to 1750°C at a rate of 5°C / min, and keep it for 4 hours in an argon atmosphere for sintering. After cooling, the finished ceramic bonding tool is obtained.

[0054] Example 3

[0055] (1) Preparation of Silicon Carbide Nanofibers

[0056] Add 100 g of polycarbosilane and 400 ml of xylene to a 500 ml three-necked flask, stir and dissolve. Add 2.5 g of platinum dichloride catalyst, and reflux and react in an oil bath at 180°C for 6 hours. Place the reaction product in a tubular furnace, heat it up to 1000°C at a rate of 5°C / min, and keep it for 2 hours for pyrolysis. Then heat it up to 1600°C at a rate of 10°C / min and keep it for 4 hours for carbothermal reduction to obtain silicon carbide nanofibers.

[0057] (2) Preparation of Ceramic Bonding Tools

[0058] Weighing by mass percentage, proportionally mix 84.23% alumina, 3.87% magnesia, 2.90% yttria, and 9% silicon carbide nanofibers, and ball mill in a planetary ball mill for 24 hours. Use an LPG-5 spray drying tower for spray granulation. Dry press and form under a pressure of 200 MPa using a YH32-315T hydraulic press. Place it in a KSL-1700X high-temperature furnace, heat it up to 1750°C at a rate of 5°C / min, and keep it for 4 hours in an argon atmosphere for sintering. After cooling, the finished ceramic bonding tool is obtained.

[0059] Example 4

[0060] (1) Preparation of Silicon Carbide Nanofibers

[0061] Add 100 g of polycarbosilane and 400 ml of xylene to a 500 ml three-necked flask, stir and dissolve. Add 2.5 g of platinum dichloride catalyst, and reflux and react in an oil bath at 180°C for 6 hours. Place the reaction product in a tubular furnace, heat it up to 1000°C at a rate of 5°C / min, and keep it for 2 hours for pyrolysis. Then heat it up to 1600°C at a rate of 10°C / min and keep it for 4 hours for carbothermal reduction to obtain silicon carbide nanofibers.

[0062] (2) Preparation of Ceramic Bonding Tools

[0063] Weigh 81.45% alumina, 3.74% magnesia, 2.81% yttria, and 12% silicon carbide nanofibers by mass percentage, proportionally mix them, and ball mill in a planetary ball mill for 24 hours. Use an LPG-5 spray drying tower for spray granulation. Dry press and form at 200 MPa pressure using a YH32-315T hydraulic press. Place it in a KSL-1700X high-temperature furnace, heat it to 1750 °C at a rate of 5 °C / min, and hold for 4 hours in an argon atmosphere for sintering. After cooling, the finished ceramic cleaver is obtained.

[0064] Comparative Example 1

[0065] (1) Preparation of silicon carbide nanofibers

[0066] Add 100 g of polycarbosilane and 400 ml of xylene to a 500 ml three-necked flask, stir and dissolve. Add 2.5 g of platinum dichloride catalyst, and reflux and react in an oil bath at 180 °C for 6 hours. Place the reaction product in a tube furnace, heat it to 1000 °C at a rate of 5 °C / min, and hold for 2 hours for pyrolysis. Then heat it to 1600 °C at a rate of 10 °C / min and hold for 4 hours for carbothermal reduction to obtain silicon carbide nanofibers.

[0067] (2) Preparation of ceramic cleaver

[0068] Weigh 92.55% alumina, 4.26% magnesia, and 3.19% yttria by mass percentage (without silicon carbide nanofibers), proportionally mix them, and ball mill in a planetary ball mill for 24 hours. Use an LPG-5 spray drying tower for spray granulation. Dry press and form at 200 MPa pressure using a YH32-315T hydraulic press. Place it in a KSL-1700X high-temperature furnace, heat it to 1750 °C at a rate of 5 °C / min, and hold for 4 hours in an argon atmosphere for sintering. After cooling, the finished ceramic cleaver is obtained.

[0069] Test Example 1

[0070] Use a Polytec PSV-500-3D scanning laser Doppler vibrometer to test the ultrasonic transmission performance of ceramic cleavers with different formulations. Test conditions: input power 100 W, frequency range 20 - 150 kHz. The test results are shown in Table 1.

[0071] Table 1 Test results of ultrasonic transmission performance

[0072] Sample Effective ultrasonic transmission frequency band Maximum amplitude Example 1 20 - 120kHz 3.8μm@80kHz Example 2 20 - 90kHz 3.2μm@60kHz Example 3 20 - 130kHz 3.7μm@90kHz Example 4 20 - 135kHz 3.5μm@95kHz Comparative Example 1 20 - 60kHz 2.5μm@40kHz

[0073] The results show that the introduction of silicon carbide nanofibers significantly broadens the effective ultrasonic transmission frequency band of ceramic bonders. When the content of silicon carbide nanofibers increases from 0% to 6% (Example 1), the effective frequency band expands from 20 - 60 kHz to 20 - 120 kHz, with an increase of 100%. This is attributed to the three-dimensional network structure formed by silicon carbide nanofibers in the alumina matrix, which enhances the dynamic stiffness of the material. When the fiber content is further increased to 12% (Example 4), the frequency band only slightly increases to 135 kHz. There is an obvious marginal effect of performance gain after the fiber content exceeds 6%. The gradient transition layer formed at the interface between silicon carbide nanofibers and the matrix can effectively transmit broadband vibrations, while the local agglomeration phenomenon caused by high-content fibers will trigger acoustic wave scattering, restricting the continuous improvement of high-frequency response ability.

[0074] In addition, the improvement of ultrasonic amplitude by silicon carbide nanofibers shows a non-linear response characteristic. At a content of 6% (Example 1), the maximum amplitude reaches 3.8 μm, which is 52% higher than that of Comparative Example 1 without fiber addition. At this time, the bridging effect and crack deflection mechanism of the fibers reach the best synergistic state. When the content exceeds 6%, the amplitude shows a downward trend (Example 3: 3.7 μm, Example 4: 3.5 μm), mainly because the interface defects caused by excessive fibers increase the energy dissipation.

[0075] By making a ceramic bonder by mixing a certain proportion of silicon carbide nanofibers with alumina, magnesia, and yttria, the effective ultrasonic transmission frequency band can be significantly expanded, the maximum amplitude can be increased, and the bonding performance of the ceramic bonder can be improved. Among them, the addition of 6% silicon carbide nanofibers forms an optimal microstructure in the ceramic bonder material, which is conducive to the synergistic improvement of bonding efficiency and quality.

[0076] Test Example 2

[0077] Bonding experiments were carried out on a Kulicke & Soffa ultrasonic bonder using the ceramic bonders of Example 1 (6% silicon carbide nanofibers) and Comparative Example 1 (0% silicon carbide nanofibers). During the bonding process, the ceramic bonder needs to transfer ultrasonic energy to the contact interface between the wire (such as gold wire / copper wire) and the chip, and destroy the surface oxide layer through high-frequency vibration and promote atomic bonding. Bonding parameters: power 80 W, frequency 80 kHz, pressure 40 g, time 20 ms. 100 bonding points were tested, and the bonding test results are shown in Table 2.

[0078] Table 2 Ultrasonic Bonding Test Results

[0079] Sample Average bonding time Qualified rate Average shear strength Example 1 15ms 99％ 30gf Comparative Example 1 20ms 95％ 25gf

[0080] It can be seen from the test data in Table 2 that the ceramic capillary (Example 1) with 6% silicon carbide nanofibers added has achieved an overall improvement in ultrasonic bonding performance compared to the capillary product without nanofibers added (Comparative Example 1). Under the same process parameters, the average bonding time of Example 1 is shortened by 25%, indicating that the three-dimensional network structure constructed by silicon carbide nanofibers significantly improves the transmission efficiency of ultrasonic energy, enabling the bonding interface to reach the energy threshold required for atomic diffusion faster; the bonding qualification rate is increased from 95% to 99%, and the average shear strength is significantly improved, indicating that the prepared capillary can effectively inhibit the generation of microcracks during the bonding process and enhance the structural stability of the material bonding nodes under dynamic loads.

[0081] In summary, the capillary prepared by the present invention has excellent ultrasonic transmission performance, expands the effective frequency range and increases the amplitude, can achieve the coordinated optimization of bonding efficiency, reliability and mechanical strength, meets the stringent requirements of the thermal ultrasonic bonding process for semiconductor integrated circuits, and can achieve higher bonding efficiency and better bonding quality.

[0082] The above embodiments are exemplary, and their purpose is to illustrate the technical concept and characteristics of the present invention, so that those skilled in this field can understand the content of the present invention and implement it accordingly, and it should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A ceramic splitting knife, characterized in that: The mixed raw material for preparing the ceramic splitter includes the following components by mass percentage: Alumina: 80-90%; Magnesium oxide: 3-5%; Yttrium oxide: 2-4%; Silicon carbide nanofiber: 3-12%; The ceramic splitting knife is made by molding and sintering the mixed raw material.

2. The ceramic splitting knife according to claim 1, characterized in that: The mixed raw material includes the following components by mass percentage: Alumina: 80-90%; Magnesium oxide: 3-5%; Yttrium oxide: 2-4%; Silicon carbide nanofibers: 6±0.5%.

3. The ceramic splitting knife according to claim 1, characterized in that: The mixed raw material includes the following components by mass percentage: Alumina: 87±1%; Magnesium oxide: 4±0.5%; Yttrium oxide: 3±0.5%; Silicon carbide nanofibers: 6±0.5%.

4. The method for preparing a ceramic splitting knife according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1: preparing silicon carbide nanofibers; Step S2: mixing aluminum oxide, magnesium oxide, yttrium oxide and silicon carbide nanofibers according to a predetermined mass percentage and ball milling to obtain a mixed raw material; Step S3: spray granulating the mixed raw material obtained after ball milling to obtain powder particles; Step S4: forming the powder particles obtained by granulation to obtain a green body; Step S5: sintering the formed green body at high temperature under a protective atmosphere to obtain a ceramic splitting knife.

5. The method for preparing a ceramic splitting knife according to claim 4, characterized in that: In step S1, the preparation of silicon carbide nanofibers includes the following steps: (a) adding polycarbosilane and xylene into a reaction container and stirring to dissolve; (b) adding platinum dichloride catalyst and reacting at 170-185° C. for 4-8 hours; (c) heating the reaction product to 950-1050° C. in a heating furnace and maintaining the temperature for 1.5-3 hours to perform pyrolysis; (d) further heating to 1550-1650° C. and keeping the temperature for 3-5 hours to perform carbothermal reduction to obtain silicon carbide nanofibers.

6. The method for preparing a ceramic splitting knife according to claim 4, characterized in that: In step S2, the material is ball-milled in a planetary ball mill for 18-30 hours to obtain a mixed raw material.

7. The method for preparing a ceramic splitting knife according to claim 4, characterized in that: In step S3, the mixed raw material obtained after ball milling is transported to a centrifugal spray drying tower for spray granulation to obtain powder particles.

8. The method for preparing a ceramic splitting knife according to claim 4, characterized in that: In step S4, the pressing pressure is 150-250 MPa.

9. The method for preparing a ceramic splitting knife according to claim 4, characterized in that: In step S5, the sintering temperature is 1700-1800° C., and the sintering time is 3-5 hours.

10. Use of the ceramic splitting knife according to any one of claims 1 to 3, characterized in that: The ceramic chopper is used for thermal ultrasonic bonding packaging of semiconductor integrated circuit chips. During the bonding process, the ceramic chopper transmits ultrasonic energy to the contact interface between the metal wire and the chip, promotes atomic-level bonding of the contact interface, and realizes electrical connection between the chip and the external circuit.