Method for measuring volume resistivity of aluminum nitride ceramic disc of electrostatic chuck

Abstract

The invention discloses a method for measuring the volume resistivity of an aluminum nitride ceramic plate of an electrostatic chuck, and belongs to the technical field of electrostatic chucks, and the method comprises the following steps: S1, preparing a sample: preparing an aluminum nitride ceramic plate, fully soaking the aluminum nitride ceramic plate in isopropanol to remove dirt on the surface of the aluminum nitride ceramic plate, then taking out the aluminum nitride ceramic plate, and drying the aluminum nitride ceramic plate for later use; s2, silver paste is prepared, high-temperature sintering type silver paste is prepared, and the solid content of the silver paste is 70-80%; s3, after the printing screen is printed and fixed, an electrode pattern is accurately printed on the aluminum nitride ceramic wafer; s4, heat treatment is conducted, specifically, the printed sample is dried and subjected to heat treatment in a sintering furnace, the heat treatment temperature ranges from 500 DEG C to 850 DEG C, heat preservation is conducted for 0.5 h to 1.5 h, and a silver layer printed with an electrode pattern is converted into a compact and bright silver electrode with excellent conductivity and adhesive force from a non-conductive green body; and S5, installing and connecting the samples printed with the electrodes, and sequentially measuring normal-temperature volume resistivity and high-temperature volume resistivity and surface resistivity by adjusting the muffle furnace.

Description

Technical Field

[0001] This invention relates to the field of electrostatic chuck technology, and in particular to a method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck. Background Technology

[0002] Volume resistivity and surface resistivity are important parameters for measuring the electrical properties of materials and are widely used in semiconductors, new energy, automotive electronics, materials chemistry, and component testing technologies. Existing simple methods for measuring the high-temperature volume resistivity of aluminum nitride ceramics involve using a muffle furnace and a high-resistivity meter. However, this method suffers from abnormal current readings and displays a VAL (meaning invalid value) at the interface, indicating poor contact between the sample and the electrode. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck, so as to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0005] A method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck, the method comprising:

[0006] Step S1: Sample preparation

[0007] Prepare aluminum nitride ceramic sheets by fully immersing them in isopropanol to remove surface contaminants, then removing and drying them for later use.

[0008] Step S2: Preparation of silver paste

[0009] High-temperature sintering silver paste was prepared, with a solid content of 70-80%.

[0010] Step S3: Printing

[0011] After fixing the printing screen, the electrode pattern is precisely printed on the aluminum nitride ceramic sheet;

[0012] Step S4: Heat treatment

[0013] After printing, the sample is dried and then heat-treated in a sintering furnace at a temperature of 500–850°C for 0.5–1.5 hours. The silver layer printed with the electrode pattern is transformed from a non-conductive green blank into a dense, bright silver electrode with excellent conductivity and adhesion.

[0014] Step S5: Installation

[0015] The sample with the printed electrodes was installed and connected, and the volume resistivity and surface resistivity at room temperature and high temperature were measured sequentially by adjusting the muffle furnace.

[0016] Preferably, in step S2, the method for preparing silver paste includes: mixing silver powder particles, glass powder, organic binder and solvent evenly to prepare conductive silver paste.

[0017] Preferably, in step S4, the heat treatment includes:

[0018] The printed sample is dried at 100–150°C to evaporate the solvent, and then heat-treated in a sintering furnace at 700–850°C. During this process, the organic binder is burned off, the glass powder is melted, and the silver particles are firmly bonded to the aluminum nitride ceramic sheet. The silver particles fuse together to form a continuous, dense, and highly conductive silver electrode.

[0019] Preferably, in step S3, silver paste is printed onto an aluminum nitride ceramic sheet according to the designed electrode pattern using a printing screen.

[0020] Preferably, the electrode pattern is printed according to the shape of the electrode silver block used during measurement. The electrode silver block includes annular silver blocks and disc-shaped silver blocks. The electrode pattern includes annular electrode patterns that cooperate with the annular silver blocks and circular electrode patterns that cooperate with the disc-shaped silver blocks.

[0021] The above technical solution has the following beneficial effects:

[0022] This invention significantly improves the accuracy of volume resistivity measurement by introducing a protective electrode pattern to shield the interference of surface leakage current. A printing silver plating process is used between the aluminum nitride ceramic sample and the electrode to reduce the contact resistance to a negligible level, avoiding systematic errors caused by poor electrical contact. Temperature conversion is achieved through a muffle furnace, enabling accurate measurement of volume resistivity and surface resistivity under both room temperature and high temperature conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck according to the present invention;

[0024] Figure 2 A schematic diagram of the structure of the printed electrode pattern shape;

[0025] Figure 3 This is a schematic diagram of a structure for measuring volume resistivity.

[0026] Figure 4 This is a schematic diagram of the structure for measuring surface resistivity. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] The problem solved by this invention in the prior art is to improve the instability of volume resistivity measurement of aluminum nitride ceramics and to make it applicable to the measurement method of surface resistivity of aluminum nitride ceramics.

[0029] In view of this, the present invention provides a method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck, comprising the following steps:

[0030] Step S1: Sample preparation

[0031] Prepare aluminum nitride ceramic sheet 1. Immerse aluminum nitride ceramic sheet 1 fully in isopropanol to remove dirt from its surface to facilitate the next step of printing electrode patterns. Then take it out and dry it for later use.

[0032] Step S2: Preparation of silver paste

[0033] High-temperature sintering silver paste is prepared with a solid content of 70-80%. Specifically, the prepared silver paste is used for the next step of printing electrode patterns. The solid content of the silver paste is 70% or 80%. The specific preparation method of the silver paste includes: mixing silver powder particles, glass powder, organic binder and solvent evenly to make conductive silver paste.

[0034] Step S3: Printing

[0035] After fixing the printing screen, the electrode pattern is precisely printed on the aluminum nitride ceramic sheet 1; the silver paste is printed onto the aluminum nitride ceramic sheet 1 according to the designed electrode pattern through the printing screen; the electrode pattern is printed according to the shape of the electrode silver block used in the measurement, the electrode silver block includes annular silver block and disc-shaped silver block 3, and the electrode pattern includes annular electrode pattern 5 that cooperates with the annular silver block and circular electrode pattern 6 that cooperates with the disc-shaped silver block 3.

[0036] Step S4: Heat treatment

[0037] After printing, the sample is dried and then heat-treated in a sintering furnace at a temperature of 500–850°C for 0.5–1.5 hours. This transforms the non-conductive silver layer of the electrode pattern into a dense, bright silver electrode with excellent conductivity and adhesion. Specifically, the heat treatment temperature is 850°C, and the sample is held at 850°C for 0.5 or 1 hour, followed by cooling. Alternatively, the heat treatment temperature can be 500°C, with a holding time of 1.5 hours, followed by cooling.

[0038] The above heat treatment includes: drying the printed sample at a temperature of 100-150°C to evaporate the solvent, and then heat-treating it in a sintering furnace at a temperature of 700-850°C. During this process, the organic binder is burned off, the glass powder is melted, and the silver particles are firmly bonded to the aluminum nitride ceramic sheet 1. The silver particles are fused together to form a continuous, dense, and highly conductive silver electrode layer.

[0039] Specifically, the printed sample is first dried at 100°C or 150°C to evaporate the solvent, and then heat-treated in a sintering furnace at 700°C or 850°C for 0.5h or 1h to complete the heat treatment. After heat treatment, the silver particles are firmly bonded to the aluminum nitride ceramic sheet 1, and the silver particles are fused together to form a continuous, dense, and highly conductive silver electrode layer.

[0040] Step S5: Installation

[0041] The sample with the printed electrodes was installed and connected, and the volume resistivity and surface resistivity at room temperature and high temperature were measured sequentially by adjusting the muffle furnace.

[0042] This invention significantly improves the accuracy of volume resistivity measurement by introducing a protective electrode to shield the interference of surface leakage current. A silver-plating process is used between the aluminum nitride ceramic sample 1 and the electrode to reduce the contact resistance to a negligible level, avoiding systematic errors caused by poor electrical contact. Temperature conversion is achieved through a muffle furnace, enabling accurate measurement of volume resistivity and surface resistivity under both room temperature and high temperature conditions.

[0043] To achieve the above objectives, the present invention provides the following technical solutions.

[0044] Example 1:

[0045] First, prepare a square aluminum nitride ceramic sheet 1 (40×40mm, 1mm thick), a square silver block 2 (10mm thick), a disc-shaped silver block 3 (19.6mm diameter, 10mm thick), and a ring-shaped silver block 4 (28.8mm outer diameter, 24.1mm inner diameter, 10mm thick). Assemble the aluminum nitride ceramic sheet 1 with the silver blocks. Based on the disc-shaped silver block 3 and the ring-shaped silver block 4, set electrode patterns of the same shape, specifically circular electrode pattern 6 and ring electrode pattern 5, aligned with the disc-shaped silver block 3 and the ring-shaped silver block respectively. The 10mm thick square silver block 2 is positioned at the bottom of the aluminum nitride ceramic sheet 1. (Refer to...) Figure 1 and Figure 2 ;

[0046] This application utilizes printed electrode patterns to effectively shield against interference from leakage current on the surface of the aluminum nitride ceramic sheet 1. This allows for alternating measurements of volume resistivity and surface resistivity by changing the positive and negative electrodes and protecting the electrodes. Existing technologies are prone to poor electrical contact issues. The surface of the aluminum nitride ceramic sheet 1 may have an oxide layer, contamination, or roughness, leading to poor contact between the electrode and the sample and resulting in high contact resistance. By plating a silver electrode layer on the test contact surface, the high conductivity and good ductility of the silver electrode layer allow it to adhere tightly to the sample surface, significantly reducing contact resistance and making the measurement results closer to the true volume resistivity of the sample. Therefore, this invention improves poor electrical contact by printing silver plating before testing.

[0047] refer to Figure 3 and Figure 4 These are schematic diagrams for measuring volume resistivity and surface resistivity, respectively. When measuring volume resistivity, the square silver block 2 at the bottom of the aluminum nitride ceramic sheet 1 is the positive electrode, and the disc-shaped silver block 3 is the negative electrode. Both are electrically connected to the high-resistivity meter 7 and connected in series with a power supply. The annular silver block 4 serves as a protective electrode. When measuring surface resistivity, the square silver block 2 at the bottom of the aluminum nitride ceramic sheet 1 is the protective electrode, the disc-shaped silver block 3 is the negative electrode, and the annular silver block 4 is the positive electrode. The high-resistivity meter 7 and a power supply are connected in series. Refer to the specific wiring diagram. Figure 3 and Figure 4 .

[0048] The printing and silver plating steps are as follows:

[0049] 1. Paste preparation: Silver powder particles, glass powder (flux), organic binder and solvent are mixed to prepare conductive silver paste with a specific viscosity;

[0050] 2. Printing: The silver paste is printed onto the surface of the ALN ceramic sample according to the designed electrode pattern (as shown in the figure below) using a printing screen;

[0051] 3. Heat treatment: Evaporate the solvent at 100-150°C and perform heat treatment in a sintering furnace (500-850°C). During this process: the organic binder is burned off, the glass powder melts, the silver particles are firmly bonded to the sample substrate, and the silver particles fuse together to form a continuous, dense, and highly conductive silver layer.

[0052] The aluminum nitride ceramic sheet 1 sample, after being plated with a silver electrode layer and heat-treated, was connected to a silver block and a high-resistivity meter as follows, and the volume resistivity and surface resistivity were measured respectively:

[0053] The volume resistivity and surface resistivity measured by the method described in the above technical solution of this invention have small errors and high accuracy. Moreover, the temperature can be controlled by a muffle furnace, so as to test the volume resistivity and surface resistivity under high temperature conditions.

[0054] This invention significantly improves the accuracy of volume resistivity measurement by introducing a silver electrode layer to shield the interference of surface leakage current. A silver-plating process is used between the aluminum nitride ceramic sample 1 and the electrode to reduce the contact resistance to a negligible level, avoiding systematic errors caused by poor electrical contact. Temperature conversion is achieved through a muffle furnace, enabling accurate measurement of volume resistivity and surface resistivity under both room temperature and high temperature conditions.

[0055] The direct measurement data before and after the improvement by setting the silver electrode layer are shown in Table 1 below.

[0056] Table 1:

[0057]

[0058] Based on the data from outsourced testing, a comparison shows that the data obtained after the improvement is closer to the data from outsourced testing. In other words, the data measured after setting up the silver electrode layer significantly improved the accuracy of volume resistivity measurement.

[0059] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck, characterized in that, The measurement method includes: Step S1: Sample preparation Prepare aluminum nitride ceramic sheets by fully immersing them in isopropanol to remove surface contaminants, then removing and drying them for later use. Step S2: Preparation of silver paste High-temperature sintering silver paste was prepared, with a solid content of 70-80%. Step S3: Printing After fixing the printing screen, the electrode pattern is precisely printed on the aluminum nitride ceramic sheet; Step S4: Heat treatment After printing, the sample is dried and then heat-treated in a sintering furnace at a temperature of 500–850°C for 0.5–1.5 hours. The silver layer printed with the electrode pattern is transformed from a non-conductive green blank into a dense, bright silver electrode with excellent conductivity and adhesion. Step S5: Installation The sample with the printed electrodes was installed and connected, and the volume resistivity and surface resistivity at room temperature and high temperature were measured sequentially by adjusting the muffle furnace.

2. The method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck according to claim 1, characterized in that, In step S2, the method for preparing silver paste includes: mixing silver powder particles, glass powder, organic binder and solvent evenly to prepare conductive silver paste.

3. The method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck according to claim 2, characterized in that, In step S4, the heat treatment includes: The printed sample is dried at 100–150°C to evaporate the solvent, and then heat-treated in a sintering furnace at 700–850°C. During this process, the organic binder is burned off, the glass powder is melted, and the silver particles are firmly bonded to the aluminum nitride ceramic sheet. The silver particles fuse together to form a continuous, dense, and highly conductive silver electrode.

4. The method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck according to claim 1, characterized in that, In step S3, silver paste is printed onto an aluminum nitride ceramic sheet according to the designed electrode pattern using a printing screen.

5. The method for measuring the volume resistivity of an aluminum nitride ceramic disk in an electrostatic chuck according to claim 4, characterized in that, The electrode pattern is printed according to the shape of the electrode silver block used during measurement. The electrode silver block includes annular silver blocks and disc-shaped silver blocks. The electrode pattern includes annular electrode patterns that cooperate with the annular silver blocks and circular electrode patterns that cooperate with the disc-shaped silver blocks.

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