Embedded electrode aluminum nitride electrostatic chuck and manufacturing method thereof

Abstract

The invention belongs to the technical field of semiconductor manufacturing equipment, and particularly relates to an embedded electrode aluminum nitride electrostatic chuck and a manufacturing method thereof. Presetting a tungsten paste electrode pattern on the surface of the aluminum nitride green body by adopting a screen printing technology; carrying out adhesive removal treatment on the aluminum nitride green body printed with the electrode, and then co-firing in an N2-H2 mixed atmosphere; and processing a micro-bulge array on the surface of the electrostatic chuck by using a laser processing technology. According to the electrostatic chuck, the electrostatic adsorption response time is shortened to 0.28 seconds, a wafer can be fixed more quickly in the semiconductor manufacturing process, and the production efficiency is improved. Due to the design of the surface micro-bulge array, the contact area of the wafer and the chuck is reduced, and meanwhile, the adhesion possibility of particles on the surface of the chuck is reduced. Through an accurately-controlled low-temperature co-firing process, good co-densification of the electrode and the ceramic substrate is realized, and long-term stable work of the electrostatic chuck in a complex process environment is ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor manufacturing equipment, and particularly relates to an embedded electrode aluminum nitride electrostatic chuck and a manufacturing method thereof. The electrostatic chuck is mainly applied to processes such as plasma etching and chemical vapor deposition in the semiconductor manufacturing process, and is used for stably adsorbing and fixing a wafer to meet the requirements of high-precision and high-stability semiconductor manufacturing processes. BACKGROUND

[0002] In the field of semiconductor manufacturing, as chip manufacturing processes continue to move towards smaller sizes, the performance requirements for electrostatic chucks are increasingly stringent. As a key component in semiconductor manufacturing equipment, the electrostatic chuck functions to stably fix a wafer on the chuck surface through electrostatic adsorption force, ensuring the positional accuracy and stability of the wafer during processes such as plasma treatment, etching, and deposition. Aluminum nitride material has become an ideal material for manufacturing electrostatic chucks due to its high thermal conductivity, good electrical insulation, and excellent plasma corrosion resistance.

[0003] However, traditional aluminum nitride electrostatic chuck manufacturing methods have many problems. In terms of electrode preparation, previous methods are difficult to achieve high-precision and fine-line electrode pattern fabrication, resulting in insufficient bonding strength between the electrode and the ceramic substrate, which can lead to electrode shedding, short circuiting, and other problems during long-term use, affecting the performance and service life of the electrostatic chuck. For example, some conventional electrode printing techniques cannot accurately control the electrode line width, resulting in low resolution of the electrode pattern, making it difficult to meet the requirements of advanced processes for high adsorption force and fast response of the electrostatic chuck.

[0004] In terms of sintering process, the traditional sintering temperature and atmosphere control are not precise enough, and the electrode and ceramic substrate cannot achieve perfect co-densification, resulting in defects such as pores and cracks in the electrostatic chuck, affecting its thermal conductivity and mechanical strength. Moreover, the traditional manufacturing method is relatively rough in surface treatment of the electrostatic chuck, and it is difficult to form specific microstructures to optimize the contact state between the wafer and the chuck, thereby affecting the electrostatic adsorption effect and particle contamination control. In the semiconductor manufacturing process, particle contamination can seriously affect the yield and performance of chips, so how to reduce the particle contamination of the electrostatic chuck on the wafer is a key problem that needs to be solved. With the continuous development of semiconductor manufacturing technology, the limitations of existing aluminum nitride electrostatic chuck manufacturing methods have become increasingly prominent, and there is an urgent need for an innovative manufacturing method to meet the industry's demand for high-performance electrostatic chucks. SUMMARY

[0005] The present application aims to solve the technical problems of low electrode preparation precision, poor co-densification effect of electrode and ceramic matrix, difficult accurate control of surface microstructure, and high risk of particulate pollution in the existing manufacturing method of aluminum nitride electrostatic chuck, and provides a manufacturing method of aluminum nitride electrostatic chuck with high-precision embedded electrode, excellent co-densification performance, specific surface microstructure and low particulate pollution, so as to meet the strict requirements of advanced semiconductor processes on the high performance of electrostatic chuck.

[0006] The specific technical scheme is: A kind of embedded electrode aluminum nitride electrostatic chuck, and its manufacturing method is: Electrode printing: using advanced screen printing technology, prepositioning tungsten slurry electrode pattern on the surface of aluminum nitride green body. The viscosity of tungsten slurry is accurately controlled to be 25±3Pa s (25℃), a stainless steel screen of 320 mesh, a latex film thickness of 15 μm, and a tension of 25 N are selected to ensure the accuracy of electrode printing. During the printing process, the printing pressure is controlled at 0.8±0.1MPa, and the printing speed is 30±5mm / s. By optimizing the printing process parameters, a fine pattern with a line width of 45±5μm and a spacing of 200μm is realized, and the line width accuracy can reach ≤50μm, which can meet the high precision requirements of electrode pattern for advanced semiconductor processes.

[0007] Co-firing process: using low-temperature co-firing process, the aluminum nitride green body with printed electrode is first treated at a low temperature of 500℃ in N2 atmosphere at a heating rate of 1℃ / min. The main purpose of this stage is to remove organic matter such as binder from the green body (debinding). The debinding time is controlled at 3±0.5h to ensure that the binder is fully removed. Subsequently, co-firing is carried out at 1450℃, 10MPa for 2h in N2-H2 mixed atmosphere (H2 content 5%). The rate of temperature rise to co-firing temperature is controlled at 3±0.5℃ / min, and the rate of temperature drop is controlled at 2±0.5℃ / min. This precisely controlled co-firing process can realize good co-densification of tungsten electrode and aluminum nitride ceramic matrix, ensure high bonding strength between electrode and ceramic, and reduce defects such as pores and cracks in the internal structure.

[0008] Surface microstructure processing: laser processing technology is used to process micro-protrusion array on the surface of the electrostatic chuck. The diameter of the protrusion is accurately controlled to be 20μm, the height is 8μm, the spacing is 100μm, and the surface roughness Ra is 0.08μm. During the laser processing process, the laser energy density is controlled at 3±0.5J / cm², the pulse frequency is 20±5kHz, and the scanning speed is 100±10mm / s. Through this surface microstructure design, the contact area between wafer and electrostatic chuck is reduced by 40%, which effectively improves the electrostatic adsorption effect and reduces the risk of particulate pollution.

[0009] The present application has the beneficial effects of: Fast adsorption response: By optimizing the electrode design and surface microstructure, the electrostatic chuck manufactured by the present application shortens the electrostatic adsorption response time to 0.28 seconds, which is 62% shorter than that of the traditional chuck. Fast adsorption response can fix the wafer faster in the semiconductor manufacturing process, improve production efficiency, and meet the needs of high-speed and high-precision processes.

[0010] Low particle contamination: The design of the surface micro-protrusion array reduces the contact area between the wafer and the chuck, while also reducing the possibility of particle attachment on the chuck surface. Test results show that the desorption of residual particles is only 0.07 / cm², which is 82% less than that of the traditional chuck, effectively reducing the risk of wafer contamination by particles and improving the yield of chip manufacturing.

[0011] High stability: The precisely controlled low-temperature co-firing process enables the electrode and the ceramic matrix to achieve good co-densification. In the 200 RT-400℃ thermal cycle test, the adsorption force changes less than 2.5%, showing excellent thermal cycle stability, ensuring that the electrostatic chuck can work stably for a long time in complex process environments. DETAILED DESCRIPTION

[0012] Example 1: Preparation of embedded electrode aluminum nitride electrostatic chuck Electrode printing: First, prepare a high-quality aluminum nitride green body to ensure its surface is flat and clean. Mix tungsten powder with an appropriate amount of organic binder to prepare a tungsten paste with a viscosity of 25 Pa s (25℃). Select a stainless steel screen with a specification of 320 mesh, a latex film thickness of 15 μm, and a tension of 25 N, and install it on a screen printing device. Apply the prepared tungsten paste evenly to the screen, set the printing pressure to 0.8 MPa, and the printing speed to 30 mm / s. By precisely controlling the printing pressure, speed, and other parameters, the electrode pattern is printed on the surface of the aluminum nitride green body. After measurement, the electrode line width is 45 μm, and the spacing is 200 μm, meeting the design requirements.

[0013] Co-firing process: Place the aluminum nitride green body with the printed electrode pattern into a high-temperature furnace. First, slowly raise the temperature to 500℃ at a rate of 1℃ / min under N2 atmosphere, and maintain the temperature for 3h to ensure that the organic matter such as binder in the green body is fully discharged (debinding). After debinding is completed, switch the high-temperature furnace to N2-H2 mixed atmosphere (H2 content 5%), raise the temperature to 1450℃ at a rate of 3℃ / min, and apply a pressure of 10 MPa. Maintain the conditions for 2h to fully co-sinter the tungsten electrode and the aluminum nitride ceramic matrix, achieving co-densification. Then, reduce the temperature to room temperature at a rate of 2℃ / min.

[0014] Surface microstructure processing: High-precision laser processing equipment was used to process a micro-protrusion array on the surface of the co-fired aluminum nitride electrostatic chuck. According to design requirements, the laser energy density was precisely set to 3 J / cm², the pulse frequency to 20 kHz, and the scanning speed to 100 mm / s. A micro-protrusion array with a diameter of 20 μm, a height of 8 μm, and a spacing of 100 μm was then processed on the electrostatic chuck surface. After processing, the surface roughness was measured using a surface roughness measuring instrument, and the surface roughness Ra = 0.08 μm.

[0015] Example 2: Preparation of electrostatic chucks of different sizes Electrode Printing: For electrostatic chucks of varying sizes, select aluminum nitride green blanks of appropriate dimensions. Adjust the amount of tungsten paste to ensure uniform coverage of the green blank surface for electrode pattern printing. A viscosity of 24 Pa is also used. The tungsten paste was prepared at 25℃, and the screen specifications remained unchanged. The printing pressure was adjusted to 0.85MPa, and the printing speed was 28mm / s. Electrode patterns conforming to the design were printed on the surface of the aluminum nitride green blank. The electrode linewidth was controlled at 43μm, and the spacing was 200μm.

[0016] Co-firing process: The preform with printed electrodes is placed in a high-temperature furnace. The debinding process is the same as in Example 1. The temperature is increased at 1℃ / min in a N2 atmosphere at 500℃ and held for 3.2h. During co-firing, the heating rate is adjusted to 3.2℃ / min to 1450℃, and the temperature is held for 2h in a N2-H2 mixed atmosphere (H2 content 5%) and a pressure of 10MPa. The cooling rate is 2.2℃ / min.

[0017] Surface microstructure processing: Using laser processing equipment, the laser energy density was set to 3.2 J / cm², the pulse frequency to 22 kHz, and the scanning speed to 95 mm / s. A micro-protrusion array with a diameter of 20 μm, a height of 8 μm, and a spacing of 100 μm was processed, and the surface roughness Ra was controlled at around 0.08 μm.

[0018] Example 3: Preparation of an electrostatic chuck under optimized parameters Electrode printing: Select a viscosity of 26 Pa. The tungsten paste was prepared at 25°C, and the screen parameters remained unchanged. The printing pressure was 0.75 MPa, and the printing speed was 32 mm / s. Electrode patterns were printed on the aluminum nitride green blank, and the final electrode linewidth reached 47 μm with a spacing of 200 μm.

[0019] Co-firing process: After debinding, the temperature is increased at 1℃ / min in a N2 atmosphere at 500℃ and held for 2.8h. During co-firing, the temperature is increased to 1450℃ at 2.8℃ / min and held for 2h in a N2-H2 mixed atmosphere (H2 content 5%) and a pressure of 10MPa, with a cooling rate of 1.8℃ / min.

[0020] Surface microstructure processing: During laser processing, the energy density is set to 2.8 J / cm², the pulse frequency is 18 kHz, and the scanning speed is 105 mm / s to process a micro-protrusion array that meets the requirements, with a surface roughness Ra = 0.08 μm.

[0021] Performance testing: A comprehensive performance test was conducted on the embedded electrode aluminum nitride electrostatic chuck prepared in the above embodiments, and the results are as follows: (1) Adsorption Response Time Test: A dedicated electrostatic adsorption response time test platform was built to simulate the electrostatic adsorption process in actual semiconductor manufacturing. The wafer was placed on the surface of the electrostatic chuck, and a standard electrostatic adsorption voltage was applied. The time for the electrostatic chuck to adsorb the wafer was measured using a high-speed camera and precision timing equipment. After multiple tests, the average adsorption response time of the electrostatic chuck prepared in Example 1 was 0.28 seconds, in Example 2 it was 0.29 seconds, and in Example 3 it was 0.27 seconds, all of which were significantly shorter than the 0.74 seconds of the traditional chuck.

[0022] (2) Desorption Residual Particle Test: After completing the cycle test of adsorption and desorption of wafers, a high-sensitivity particle detection device was used to scan and detect the surface of the electrostatic chuck. The number of desorption residual particles per square centimeter was counted. After multiple tests and data statistics, the average number of desorption residual particles in the electrostatic chuck prepared in Example 1 was 0.07 particles / cm², in Example 2 it was 0.08 particles / cm², and in Example 3 it was 0.06 particles / cm², while the average number of desorption residual particles in the traditional chuck was 0.39 particles / cm². The number of desorption residual particles in the electrostatic chuck manufactured by the present invention was significantly reduced.

[0023] (3) Thermal Cycling Stability Test: The electrostatic chuck was placed in a thermal cycling test device and subjected to 200 cycles from room temperature (RT) to 400°C. During each thermal cycle, the change in the adsorption force of the electrostatic chuck was measured. After testing, the maximum change in the adsorption force of the electrostatic chuck prepared in Example 1 was less than 2.5%, in Example 2 it was less than 2.3%, and in Example 3 it was less than 2.2%, indicating that the electrostatic chuck manufactured by this invention has excellent thermal cycling stability.

[0024] The above test results fully demonstrate that the embedded electrode aluminum nitride electrostatic chuck manufacturing method provided by the present invention can produce electrostatic chucks with excellent performance, fully meeting the stringent requirements of advanced semiconductor processes for electrostatic chucks, and has significant technical advantages and broad application prospects.

Claims

1. A method for manufacturing an embedded electrode aluminum nitride electrostatic chuck, characterized in that, Includes the following steps: Electrode printing: Tungsten paste electrode patterns are pre-printed on the surface of the aluminum nitride green blank using screen printing technology; Co-firing process: The aluminum nitride green blank with printed electrodes is first debinded, and then co-fired in a N2-H2 mixed atmosphere; Surface microstructure processing: Laser processing technology is used to process an array of micro-protrusions on the surface of an electrostatic chuck.

2. The method for manufacturing an embedded electrode aluminum nitride electrostatic chuck according to claim 1, characterized in that, In electrode printing, the viscosity of tungsten paste is 25±3 Pa. The screen is made of 320-mesh stainless steel, the latex film is 15μm thick, and the tension is 25N; the printed electrode line width is 45±5μm, and the spacing is 200μm. The printing pressure is controlled at 0.8±0.1MPa, and the printing speed is 30±5mm / s.

3. The method for manufacturing an embedded electrode aluminum nitride electrostatic chuck according to claim 1, characterized in that, In the co-firing process, the binder is removed in an N2 atmosphere at 500℃ at a heating rate of 1℃ / min for 3±0.5h. In an N2-H2 mixed atmosphere, the temperature is raised to 1450℃ and 10MPa at 3±0.5℃ / min and held for 2h for co-firing, with H2 volume content of 5%. The cooling rate is controlled at 2±0.5℃ / min.

4. The method for manufacturing an embedded electrode aluminum nitride electrostatic chuck according to claim 1, characterized in that, In the surface microstructure processing, the diameter of the protrusions is controlled to be 20μm, the height to be 8μm, the spacing to be 100μm, and the surface roughness Ra=0.08μm; during the laser processing, the laser energy density is controlled at 3±0.5J / cm², the pulse frequency is 20±5kHz, and the scanning speed is 100±10mm / s.

5. An embedded electrode aluminum nitride electrostatic chuck, obtained by the manufacturing method of an embedded electrode aluminum nitride electrostatic chuck according to any one of claims 1 to 4.