Vacuum brazing method for electrostatic chuck

Abstract

The invention discloses a vacuum brazing method for an electrostatic chuck, which belongs to the technical field of electrostatic chucks, and comprises the following steps: S1, taking a first ceramic block, and processing three positioning holes, a conductive column insertion hole and a groove in the first ceramic block; s2, a second ceramic block is taken, and a ceramic pressing block with the same size as the groove is machined; s3, an electrostatic chuck ceramic plate needing vacuum brazing is taken, and three ceramic plate Lift Pin holes are machined in the electrostatic chuck ceramic plate; s4, plating an adsorption electrode area exposed by the DC hole of the electrostatic chuck ceramic plate with a Ni plating layer; s5, welding flux is put into the DC hole of the electrostatic chuck ceramic plate; s6, respectively inserting the positioning pins into the positioning holes of the first ceramic block, and then correspondingly inserting the positioning pins into the Lift pin holes of the ceramic plate; s7, inserting a conductive column, and covering with a ceramic pressing block; and S8, after the ceramic pressing block is covered, the electrostatic chuck ceramic plate and the first ceramic block are put into a vacuum brazing furnace, and vacuum brazing is completed.

Description

Technical Field

[0001] The invention relates to the technical field of electrostatic chucks, and in particular to a vacuum brazing method for electrostatic chucks. Background Art

[0002] In the prior art, electrostatic chucks are mainly divided into bipolar and monopolar types according to the type of adsorption electrode. Adsorption force can only be generated after a certain voltage is applied to the adsorption electrode by an external power supply. In the process of connecting the external power supply and the adsorption electrode, the connection is usually made through a metal conductive column, one end of the conductive column is connected to the adsorption electrode, and the other end is connected to the output end of the external power supply. Due to different usage scenarios, the connection between the conductive column and the adsorption electrode mainly includes telescopic pin contact connection and vacuum brazing welding.

[0003] The main defect of the prior art using vacuum brazing is that the electrostatic chuck of the conductive column is connected by vacuum brazing. When the electrostatic chuck is manufactured and connected to the conductive column, the metal conductive column needs to be welded to the adsorption electrode in the electrode hole of the ceramic disk first. After welding, the ceramic disk with the welded conductive column is bonded to the metal base. During the bonding process, the welded conductive column needs to be inserted into the corresponding position of the metal base. Since the electrode hole of the ceramic disk is processed and manufactured before the ceramic disk is sintered, during the process of sintering the ceramic disk into porcelain, due to the influence of sintering shrinkage, the position of the electrode hole will deviate by 0.1 to 1 mm relative to the position on the drawing. Because of the deviation in the position of the electrode hole of the ceramic disk, the position of the conductive column after welding deviates from the position of the metal base for inserting the conductive column, which ultimately causes the conductive column to fail to be inserted into the metal base normally, and the ceramic disk and the metal base cannot be bonded. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a vacuum brazing method for an electrostatic chuck to solve the problem raised in the background technology.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A vacuum brazing method for an electrostatic chuck, the method comprising:

[0007] S1: Take a first ceramic block of the same material as the electrostatic chuck ceramic disk, and process three positioning holes on the first ceramic block. The aperture size and position of the three positioning holes correspond to the aperture size and position of the three lift pin holes on the metal base of the electrostatic chuck. After the three positioning holes are processed, conductive column insertion holes are processed on the first ceramic block. The number, size and position of the conductive column insertion holes are the same as those on the metal base of the electrostatic chuck. After the conductive column insertion holes are processed, grooves are processed on the upper surface of the first ceramic block. After the electrostatic chuck ceramic disk that needs vacuum brazing is placed under the first ceramic block, a gap needs to be formed with the lower surface of the first ceramic block through the positioning support of the positioning holes to facilitate the discharge of colloid in the solder during brazing;

[0008] S2: Take another second ceramic block made of the same material as the electrostatic chuck ceramic plate, and process the second ceramic block into a ceramic pressing block of the same size according to the size of the groove. The ceramic pressing block cooperates with the groove to press the conductive column during the vacuum brazing process;

[0009] S3: Take the electrostatic chuck ceramic disk that needs vacuum brazing. The electrostatic chuck ceramic disk has a built-in adsorption electrode, and three ceramic disk lift pin holes are processed on the electrostatic chuck ceramic disk. The aperture size and position of the three ceramic disk lift pin holes are the same as the size and position of the lift pin holes on the metal base of the electrostatic chuck.

[0010] S4: A Ni coating is applied to the exposed adsorption electrode area of ​​the DC hole of the electrostatic chuck ceramic disc by chemical plating or electroplating to provide thermal protection and weldability during vacuum welding;

[0011] S5: After the Ni plating of the adsorption electrode at the DC hole of the electrostatic chuck ceramic disk is completed, a solder suitable for vacuum brazing is placed in the DC hole of the electrostatic chuck ceramic disk;

[0012] S6: After the solder is placed in the DC hole of the electrostatic chuck ceramic plate, the positioning pins are respectively inserted into the positioning holes of the first ceramic block, and then the electrostatic chuck ceramic plate is placed under the first ceramic block, and the positioning pins are also correspondingly inserted into the lift pin holes of the ceramic plate;

[0013] S7: After the electrostatic chuck ceramic plate and the first ceramic block are positioned, the conductive column is inserted and the ceramic pressing block is covered;

[0014] S8: After the ceramic block is covered, the electrostatic chuck ceramic plate and the first ceramic block are placed in a vacuum brazing furnace. The vacuum brazing conditions are set to a temperature of 600-1000°C, kept warm for 10-60 minutes, and a vacuum degree of <10 -3 Pa, after the equipment operation is completed according to the process conditions, vacuum brazing is completed.

[0015] Preferably, the electrostatic chuck ceramic disk is aluminum oxide ceramic, aluminum nitride ceramic, silicon carbide ceramic, or silicon nitride ceramic.

[0016] Preferably, the adsorption electrode is made of any one of W, Mo, Mn, Ag, Au, Pt, and Pd.

[0017] Preferably, the thickness of the Ni plating layer is 3 to 10 um.

[0018] Preferably, the solder is in the form of metal solder paste or metal foil, and the solder is Ag-Cu or Ag-Cu-Ti.

[0019] The above technical solution has the following beneficial effects:

[0020] 1. This application solves the problem that the DC hole position and the corresponding position of the metal base are deviated due to the shrinkage of the ceramic during the manufacturing process of the ceramic plate, which causes the conductive column to be unable to be normally inserted into the corresponding position of the metal base after being welded to the adsorption electrode in the DC hole of the ceramic plate;

[0021] 2. The present application fully welds the conductive column and the ceramic disk adsorption electrode by vacuum brazing, which can effectively avoid abnormal electrode sparking caused by discharge at the tip of the conductive column and the electrode contact surface due to large current during power-on in some specific application environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic cross-sectional view of the electrostatic chuck vacuum brazing positioning device of the present invention. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, 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.

[0024] The present application is aimed at the problem that the electrode hole of the ceramic disk is processed and manufactured before the ceramic disk is sintered. During the process of sintering the ceramic disk into porcelain, due to the influence of sintering shrinkage, the position of the electrode hole will deviate by about 0.1 to 1 mm relative to the position on the drawing. Because of the deviation of the position of the electrode hole of the ceramic disk, the position of the conductive column after welding deviates relative to the position of the metal base for inserting the conductive column, which ultimately causes the conductive column to be unable to be normally inserted into the metal base, and the ceramic disk and the metal base cannot be fitted together;

[0025] In the prior art, an electrostatic chuck of a conductive column is connected by vacuum brazing. When the electrostatic chuck is manufactured and connected to the conductive column, the metal conductive column needs to be welded to the adsorption electrode in the electrode hole of the ceramic disk first. After the welding is completed, the ceramic disk with the welded conductive column is bonded to the metal base. During the bonding process, the welded conductive column needs to be inserted into the corresponding position of the metal base. Since the electrode hole of the ceramic disk is processed and manufactured before the ceramic disk is sintered, during the process of sintering the ceramic disk into porcelain, due to the influence of sintering shrinkage, the position of the electrode hole will deviate by about 0.1 to 1 mm relative to the position on the drawing. Due to the deviation of the position of the electrode hole of the ceramic disk, the position of the conductive column after welding deviates relative to the position of the metal base for inserting the conductive column, which ultimately causes the conductive column to be unable to be normally inserted into the metal base, and the ceramic disk and the metal base cannot be bonded;

[0026] The present application solves the above problems by using the following vacuum brazing method in conjunction with an electrostatic chuck vacuum brazing device;

[0027] refer to Figure 1 , Figure 1 The cross-sectional view of the electrostatic chuck vacuum brazing device is provided, and the electrostatic chuck vacuum brazing method using the device includes the following steps:

[0028] Step 1: Take a first ceramic block 1 of the same material as the electrostatic chuck ceramic plate 2, and process three positioning holes on the first ceramic block 1. The aperture size and position of the three positioning holes correspond to the aperture size and position of the three lift pin holes on the metal base of the electrostatic chuck. The aperture size, position, and position relationship of the three positioning holes need to be consistent with the three lift pin holes on the metal base of the electrostatic chuck. Pin holes (top column holes) are the same, so as to ensure the correctness of the position of the electrostatic chuck ceramic disk 2 during brazing. The first ceramic block 1 here simulates the electrostatic chuck metal base. After the three positioning holes are processed, the conductive column insertion holes are processed on the first ceramic block 1. The number, size and position of the conductive column insertion holes are the same as those on the electrostatic chuck metal base, so as to facilitate the positioning of the conductive column 4 during welding. After the conductive column insertion holes are processed, a groove 6 is processed on the upper surface of the first ceramic block 1. The groove 6 is used to place the ceramic pressing block 3. The ceramic pressing block 3 is used to give the conductive column 4 a force from above to press the conductive column 4 during welding to ensure the close fit of the bottom welding point of the conductive column 4 during the welding process, and to ensure the quality and reliability of brazing. The electrostatic chuck ceramic disk 2 that needs vacuum brazing needs to form a gap with the lower surface of the first ceramic block through the positioning support of the positioning hole after it is under the first ceramic block 1, so as to facilitate the discharge of colloid in the solder during brazing;

[0029] Step 2: Take another second ceramic block made of the same material as the electrostatic chuck ceramic disk 2, and process the second ceramic block into a ceramic pressing block 3 of the same size according to the size of the groove 6. The ceramic pressing block 3 is matched with the groove 6. The ceramic pressing block 3 and the groove 6 have a gap, which can be a gap fit, so as to facilitate the installation of the ceramic pressing block 3 and the groove 6 during the matching process, or take the ceramic pressing block 3 out of the groove 6. The ceramic pressing block 3 is used to press the conductive column 4 during the vacuum brazing process to ensure that the conductive column 4 can remain in contact during the welding process to ensure the quality of the welding;

[0030] Step 3: Take the electrostatic chuck ceramic disk 2 that needs vacuum brazing, the electrostatic chuck ceramic disk 2 has a built-in adsorption electrode 7, and three ceramic disk Lift Pin holes (top column holes) are processed on the electrostatic chuck ceramic disk 2, the aperture size and position of the three ceramic disk Lift Pin holes (top column holes) correspond to the size and position of the Lift Pin holes (top column holes) on the electrostatic chuck metal base, so as to facilitate the correct relative position of the electrostatic chuck ceramic disk 2 and the first ceramic block 1, and ensure that the electrostatic chuck ceramic disk 2 can be installed in conjunction with the electrostatic chuck metal base after being welded with the conductive column 4;

[0031] Step 4: The adsorption electrode area exposed by the DC hole of the electrostatic chuck ceramic disk is plated with a Ni plating layer 8 by chemical plating or electroplating to provide thermal protection and weldability during vacuum welding. The DC hole of the electrostatic chuck ceramic disk is used to allow the conductive column 4 to pass through, which is convenient for welding the conductive column and the adsorption electrode area exposed by the DC hole of the electrostatic chuck ceramic disk is a part of the adsorption electrode 7, and the other part of the adsorption electrode 7 is buried in the electrostatic chuck ceramic disk 2;

[0032] Step 5: After the Ni plating layer 8 on the adsorption electrode position exposed by the DC hole of the electrostatic chuck ceramic disk is completed, a solder suitable for vacuum brazing is placed in the DC hole of the electrostatic chuck ceramic disk. The solder can be accumulated into a solder layer 9 located on the Ni layer 8;

[0033] Step 6: After the solder layer 9 is placed in the DC hole of the electrostatic chuck ceramic disk, the positioning Pin 5 is respectively inserted into the three positioning holes of the first ceramic block 1. The positioning pin 5 is a positioning pin used for positioning. Then the electrostatic chuck ceramic disk 2 is placed under the first ceramic block 1. The positioning Pin 5 is also correspondingly inserted into the Lift Pin hole (top column hole) of the ceramic disk. The Lift Pin hole (top column hole) of the ceramic disk is a hole set on the electrostatic chuck ceramic disk 2 for positioning, ensuring that the relative positions of the first ceramic block 1 and the electrostatic chuck ceramic disk 2 are correct, so that the electrostatic chuck ceramic disk 2 can cooperate with the electrostatic chuck substrate after welding;

[0034] Step 7: After the electrostatic chuck ceramic plate 2 and the first ceramic block 1 are positioned, the conductive column 4 is inserted, and the ceramic pressing block 3 is covered. The conductive column 4 is inserted from the top groove 6 from top to bottom, and the bottom is in contact with the solder layer 9 after insertion, and then pressed by the ceramic pressing block 3;

[0035] Step 8: After the ceramic pressing block 3 is covered, the electrostatic chuck ceramic plate 2 and the first ceramic block 1 are placed in a vacuum brazing furnace. The vacuum brazing conditions are set at a temperature of 600-1000°C, preferably 750-850°C, and kept warm for 10-60 minutes. The holding time is preferably 35 minutes, and the vacuum degree is less than 10 -3 Pa, after the equipment runs according to the process conditions, the electrostatic chuck vacuum brazing welding is completed;

[0036] Among them, the electrostatic chuck ceramic disc is alumina ceramic or aluminum nitride ceramic or silicon carbide ceramic or silicon nitride ceramic. After the material of the electrostatic chuck ceramic disc 2 is determined, the corresponding first ceramic block 1 is made of the same material to ensure the consistency of expansion and contraction caused by heating during the vacuum brazing process;

[0037] The adsorption electrode is made of any one of W, Mo, Mn, Ag, Au, Pt, and Pd, and is selected according to needs;

[0038] The thickness of the Ni coating is 3 to 10 μm, preferably 6 to 7 μm, which is determined according to the process, equipment and other conditions;

[0039] The solder is in the form of metal solder paste or metal foil, and the solder is Ag-Cu or Ag-Cu-Ti;

[0040] The main purpose of the present application is to design a positioning device. During the sintering process of the ceramic disc, even if the position of the electrode hole relative to the drawing has a deviation of 0.1 to 1 mm, the conductive column can be welded through the positioning device to ensure that the conductive column after welding is normally inserted into the metal base, and the ceramic disc and the metal base are normally bonded.

[0041] The present application solves the problem that the DC hole position and the corresponding position of the metal base are deviated due to the shrinkage of the ceramic during the manufacturing process of the ceramic disk, which causes the conductive column to be unable to be properly inserted into the corresponding position of the metal base after being welded to the adsorption electrode in the DC hole of the ceramic disk;

[0042] The present application fully welds the conductive column and the ceramic disk adsorption electrode by vacuum brazing, which can effectively avoid abnormal electrode sparking caused by discharge at the tip of the conductive column and the electrode contact surface due to large current during power-on in some specific application environments.

[0043] The embodiments of the present invention are 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 of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A vacuum brazing method for an electrostatic chuck, characterized in that: The method comprises: S1: Take a first ceramic block of the same material as the electrostatic chuck ceramic disk, and process three positioning holes on the first ceramic block. The aperture size and position of the three positioning holes correspond to the aperture size and position of the three lift pin holes on the metal base of the electrostatic chuck. After the three positioning holes are processed, conductive column insertion holes are processed on the first ceramic block. The number, size and position of the conductive column insertion holes are the same as those on the metal base of the electrostatic chuck. After the conductive column insertion holes are processed, grooves are processed on the upper surface of the first ceramic block. After the electrostatic chuck ceramic disk that needs vacuum brazing is placed under the first ceramic block, a gap needs to be formed with the lower surface of the first ceramic block through the positioning support of the positioning holes to facilitate the discharge of colloid in the solder during brazing; S2: Take another second ceramic block made of the same material as the electrostatic chuck ceramic plate, and process the second ceramic block into a ceramic pressing block of the same size according to the size of the groove. The ceramic pressing block cooperates with the groove to press the conductive column during the vacuum brazing process; S3: Take the electrostatic chuck ceramic disk that needs vacuum brazing. The electrostatic chuck ceramic disk has a built-in adsorption electrode, and three ceramic disk lift pin holes are processed on the electrostatic chuck ceramic disk. The aperture size and position of the three ceramic disk lift pin holes are the same as the size and position of the lift pin holes on the metal base of the electrostatic chuck. S4: A Ni coating is applied to the exposed adsorption electrode area of ​​the DC hole of the electrostatic chuck ceramic disc by chemical plating or electroplating to provide thermal protection and weldability during vacuum welding; S5: After the Ni plating of the adsorption electrode at the DC hole of the electrostatic chuck ceramic disk is completed, a solder suitable for vacuum brazing is placed in the DC hole of the electrostatic chuck ceramic disk; S6: After the solder is placed in the DC hole of the electrostatic chuck ceramic plate, the positioning pins are respectively inserted into the positioning holes of the first ceramic block, and then the electrostatic chuck ceramic plate is placed under the first ceramic block, and the positioning pins are also correspondingly inserted into the lift pin holes of the ceramic plate; S7: After the electrostatic chuck ceramic plate and the first ceramic block are positioned, the conductive column is inserted and the ceramic pressing block is covered; S8: After the ceramic block is covered, the electrostatic chuck ceramic plate and the first ceramic block are placed in a vacuum brazing furnace. The vacuum brazing conditions are set to a temperature of 600-1000°C, kept warm for 10-60 minutes, and a vacuum degree of <10 -3 Pa, after the equipment operation is completed according to the process conditions, vacuum brazing is completed.

2. A vacuum brazing method for an electrostatic chuck according to claim 1, characterized in that: The electrostatic chuck ceramic disk is aluminum oxide ceramic, aluminum nitride ceramic, silicon carbide ceramic, or silicon nitride ceramic.

3. A vacuum brazing method for an electrostatic chuck according to claim 1, characterized in that: The adsorption electrode is made of any one of W, Mo, Mn, Ag, Au, Pt, and Pd.

4. A vacuum brazing method for an electrostatic chuck according to claim 3, characterized in that: The thickness of the Ni plating layer is 3-10 um.

5. A vacuum brazing method for an electrostatic chuck according to claim 1, characterized in that: The solder is in the form of metal solder paste or metal foil, and the solder is Ag-Cu or Ag-Cu-Ti.

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