A method for manufacturing an electrostatic chuck's built-in heater ceramic disc

Abstract

The application discloses a preparation method of an embedded heater ceramic disc of an electrostatic chuck, and belongs to the technical field of electrostatic chuck. The embedded heater manufacturing and resistance adjusting method comprises the following steps: S1, according to a target resistance value of the heater, a formula is combined to design as follows: R = p x (L / (W x D)), wherein L represents the length of the heater, W represents the width of the heater, D represents the thickness of the heater, and p represents the resistivity of the heater electrode paste; S2, the design value is converted into a design drawing; S3, metal powder, a binder, inorganic additive powder, a dispersing agent and an organic solvent are added into a stirrer and uniformly mixed, then are rolled and dispersed to prepare a metal electrode paste with fineness less than 10 um and viscosity of 50000-400000 cps, through the addition of inorganic powder in different proportions, the heater electrode paste with the resistivity of 1 x 10 ‑6 -1 x 10 ‑4 Ω.cm can be finally prepared; and S4, the heater design drawing is converted into a silk screen printing screen drawing paper.

Description

Technical Field

[0001] This invention relates to the field of electrostatic chuck technology, and in particular to a method for preparing a ceramic disk with a built-in heater for an electrostatic chuck. Background Technology

[0002] Generally speaking, an electrostatic chuck is made of a ceramic disk and a metal base bonded together. The ceramic disk is usually made of a simple structure consisting of a dielectric layer and adsorption electrodes. The adsorption electrodes inside the ceramic disk are used to adsorb and hold the wafer after being energized. The heating electrodes are placed outside the ceramic disk and attached between the ceramic disk and the metal base. The cooling gas path is built into the metal base. Therefore, this type of common electrostatic chuck has only adsorption electrodes inside the ceramic disk and heating electrodes attached between the ceramic disk and the metal base.

[0003] The shortcomings of existing technologies are as follows: In this type of electrostatic chuck, the ceramic disk, heating electrode, and metal base are typically assembled by bonding. During operation, because the heating electrode is attached to the outside of the ceramic disk, the heating efficiency, heat conduction rate, and temperature uniformity are all affected by the thermal conductivity of the bonding material and the consistency of the bonding layer thickness, failing to fully utilize the excellent and uniform thermal conductivity of the ceramic disk. Furthermore, in semiconductor manufacturing processes where higher temperature uniformity is required, this type of electrostatic chuck will be unusable due to its inability to provide better temperature uniformity control. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a ceramic disk with a built-in heater for an electrostatic chuck, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A method for preparing a ceramic disk with a built-in heater for an electrostatic chuck, comprising:

[0007] S1: Prepare ceramic slurry, and then use the ceramic slurry to form ceramic green sheets through a casting process. The thickness of the ceramic green sheets is 200-800 μm, and the thickness difference of a single ceramic green sheet is within ±20 μm. The ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4.

[0008] S2: The ceramic green sheet is machined to have positioning holes, interconnecting through holes, adsorption electrode holes, and heating electrode holes.

[0009] S3: Add a certain amount of metal powder to a mixer, then add binder, inorganic additive powder, dispersant, and organic solvent. The metal powder can be any one of W, Mo, Mn, Ag, Pd, or Pt metal materials. Mix them evenly in the mixer according to the proportion. After mixing evenly, use a three-roll mill to roll and disperse the mixture to produce adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry with a fineness of less than 10 μm and a viscosity of 50,000 to 300,000 cps.

[0010] S4: The interconnected conductive slurry is filled into the interconnected conductive holes of the ceramic green sheet by filling the holes. Adsorption electrodes, heating electrodes, parallel electrodes and interconnected conductive pads are fabricated by screen printing. The thickness of the printed electrodes is 5-20 μm.

[0011] S5: The dielectric layer, adsorption electrode layer, heating electrode layer, parallel electrode layer, interconnecting conductive pad, and green blank with adsorption electrode holes and heating electrode holes are positioned according to the product structure sequence and stacked together using a stacking machine. During stacking, the pressure is 20T to 500T, the temperature is 30℃ to 90℃, and the time is 1min to 20min, thereby producing a green ceramic disc with a heater built into the ceramic disc.

[0012] S6: Place the stacked green ceramic discs in a degreasing furnace and degrease and remove the glue at a temperature of 300-550°C under an air or nitrogen atmosphere. Hold the temperature at the highest temperature for 20-120 hours to remove all organic matter from the green ceramic discs.

[0013] S7: Place the degreased and degummed ceramic disc in a high-temperature sintering furnace and sinter it at a temperature of 1300-1800℃ under any one or two or more protective atmospheres of N2, H2, and Ar for 0.5-10 hours to complete the production of the ceramic disc with built-in heater.

[0014] Preferably, the manufacturing and resistance adjustment method of the built-in heater includes the following steps:

[0015] S1: Design based on the target resistance value of the heater, using the following formula:

[0016] R = ρ × (L / (W × D))

[0017] In the formula: L is the heater length, W is the heater width, D is the heater thickness, and ρ is the resistivity of the heater electrode slurry;

[0018] S2: Convert the heater design values, heater length L and heater width W, into a heater design drawing;

[0019] S3: A certain amount of metal powder, 5%–30% binder, 1%–30% inorganic additive powder, 0.1%–2% dispersant, and 20%–70% organic solvent are added to a mixer according to the specified proportions and mixed evenly. After even mixing, a three-roll mill is used for rolling and dispersing to produce a metal electrode slurry with a fineness of less than 10 μm and a viscosity of 50,000–400,000 cps. By adding different proportions of inorganic powder, a resistivity of 1×10⁻⁶ can be finally produced. -6 ~1×10 -4 Heater electrode paste with Ω.cm;

[0020] S4: Convert the heater design drawing into a screen printing stencil drawing. Use 150-500 mesh, mesh diameter 15-50um, mesh thickness 20-100um, emulsion thickness 5-20um stencil making parameters to make stencils of different specifications. Different specifications of stencils can be used to make heaters with a thickness of 5-30um by screen printing.

[0021] Preferably, in step S3 of the method for manufacturing and adjusting the resistance of the built-in heater, the metal powder is any one of W, Mo, Mn, Ag, Pd, and Pt metal materials, and the inorganic powder is any one of Al2O3, AlN, SiC, and Si3N4 materials.

[0022] Preferably, in step S3 of the method for manufacturing and adjusting the resistance of the built-in heater, the inorganic powder is any one of Al2O3, AlN, SiC, and Si3N4 materials.

[0023] The above technical solution has the following beneficial effects:

[0024] 1. The technical solution of this application produces a ceramic disk with a built-in heater required for an electrostatic chuck, and the resistance value of the heater inside the ceramic disk can be adjusted according to the required requirements;

[0025] 2. The technical solution of this application integrates the heating electrode into the ceramic disk, making full use of the advantages of ceramics having excellent and uniform thermal conductivity, and can provide the ceramic disk required for electrostatic chucks with better temperature uniformity control.

[0026] 3. The built-in heater ceramic disk of this application can be controlled in multiple points and multiple zones by adding parallel layers, so as to achieve multi-point and multi-zone heating of the built-in heater inside the ceramic disk and maximize the satisfaction of the temperature uniformity control requirements in the wafer processing and manufacturing process. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of an electrostatic chuck for placing a ceramic disk for a heater according to the present invention.

[0028] Figure 2 This is a plan view of the built-in heater of the present invention. Detailed Implementation

[0029] 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.

[0030] Example 1

[0031] The main objective of this application is to provide an electrostatic chuck with excellent temperature uniformity during wafer fabrication by embedding heating electrodes inside a ceramic disk, thus creating a ceramic disk with heating wires embedded within it. This fully utilizes the excellent and uniform thermal conductivity of the ceramic disk. Furthermore, the ceramic disk can be structured with multiple layers, and by adding parallel electrodes, multi-point and multi-zone control of the heating wires embedded in the ceramic disk can be achieved, enabling multi-point and multi-zone heating of the heaters within the ceramic disk. This provides more uniform temperature control for wafer fabrication.

[0032] The main processing and manufacturing steps involved in this application are: making ceramic slurry by ball milling, forming green sheets by tape casting, making metal conductive slurry, adsorption electrode slurry, heating electrode slurry, screen printing to form adsorption electrodes, heating electrodes, parallel electrodes, and interconnected conductive electrodes, machining positioning holes, conductive holes, and electrode holes by mechanical processing, multi-layer stacking, debinding and degreasing, and high-temperature sintering to form ceramic discs.

[0033] A ceramic green sheet of a certain thickness is formed by casting a ball-milled ceramic slurry using a casting process. Metal electrode layers, including adsorption electrodes, heating electrodes, and parallel electrodes, are then fabricated on the green sheet using screen printing. Positioning holes, interconnecting through-holes, and electrode holes for layering are machined onto the green sheet. Metal conductive slurry is filled into the interconnecting through-holes. After the metal electrodes and conductive layers inside the ceramic disc are fabricated, they are positioned using the positioning holes. Multiple layers are then stacked under specific temperature, pressure, and time conditions using a laminating machine, ensuring a tight fit between the green layers. The green ceramic disc is then complete.

[0034] A green ceramic disc is placed in a degreasing furnace, where the organic binder is removed under specific temperature and atmosphere conditions. The degreased ceramic disc is then placed in a high-temperature sintering furnace, where a multi-layer co-firing process is performed between the metal electrode and the ceramic layer under specific temperature and atmosphere conditions, sintering the ceramic disc into a porcelain-like material. This produces a ceramic disc with built-in heating electrodes that meets the mechanical and electrical performance requirements. The structure of this ceramic disc is described in [details omitted]. Figure 1 ;

[0035] The method for preparing the ceramic disk with a built-in heater in an electrostatic chuck includes the following steps:

[0036] S1: Prepare a ceramic slurry, and then use the ceramic slurry to form a ceramic green sheet through a casting process. The thickness of the ceramic green sheet is 200-800 μm, and the thickness difference of a single ceramic green sheet is within ±20 μm. The ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4. In other embodiments of this example, the thickness of the ceramic green sheet is 200 μm or 800 μm, or it can be 500 μm.

[0037] S2: The ceramic green sheet is machined to have positioning holes, interconnecting through holes 4, adsorption electrode holes 7, and heating electrode holes 8.

[0038] S3: A certain amount of metal powder is added to a mixer, and then a binder, inorganic additive powder, dispersant, and organic solvent are added. The metal powder is any one of W, Mo, Mn, Ag, Pd, and Pt metal materials. The materials are mixed evenly in the mixer according to the proportion. After being mixed evenly, the mixture is rolled and dispersed using a three-roll mill to produce adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry with a fineness of less than 10 μm and a viscosity of 50,000 to 300,000 cps. The adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry are used to prepare adsorption electrode layer 2, heating electrode layer 3, and parallel electrode layer 5, respectively. In other embodiments of this example, the viscosity of the adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry can be 50,000 cps or 300,000 cps, the fineness is 9 μm, and the viscosity can also be 150,000 cps.

[0039] S4: The interconnecting conductive slurry is filled into the interconnecting conductive holes 4 of the ceramic green sheet by filling holes. Adsorption electrodes, heating electrodes, parallel electrodes and interconnecting conductive pads 6 are fabricated by screen printing. The thickness of the printed adsorption electrodes, heating electrodes and parallel electrodes is 5 to 20 μm. In other embodiments of this example, the thickness of the printed adsorption electrodes, heating electrodes and parallel electrodes is 5 μm or 20 μm, or it can be 12 μm.

[0040] S5: Reference Figure 1 The dielectric layer 1, adsorption electrode layer 2, heating electrode layer 3, parallel electrode layer 5, interconnecting conductive pad 6, and green blank with adsorption electrode holes 7 and heating electrode holes 8 are positioned according to the product structure sequence using positioning holes. They are then stacked together using a stacking machine through positioning and stacking. During stacking, the pressure is 20T to 500T, the temperature is 30℃ to 90℃, and the time is 1min to 20min, thereby producing a green ceramic disc with a heater built into the ceramic disc. In other embodiments of this example, the pressure is 20T or 500T, the temperature is 30℃ or 90℃, and the time is 1min or 20min. Alternatively, the pressure can be 240T, the temperature is 60℃, and the time is 10min.

[0041] S6: Place the stacked green ceramic discs in a degreasing furnace and degrease and remove the glue at a temperature of 300-550°C under an air or nitrogen atmosphere. Hold the temperature at the maximum temperature for 20-120 hours to remove all organic matter from the green ceramic discs. In other embodiments of this example, degreasing and glue removal are performed at a temperature of 300°C or 550°C for a maximum temperature of 20-120 hours. Alternatively, degreasing and glue removal can be performed at a temperature of 420°C for a maximum temperature of 70 hours.

[0042] S7: Place the degreased and degummed ceramic disc in a high-temperature sintering furnace and sinter it at a temperature of 1300-1800°C under any one or two or more protective atmospheres of N2, H2, and Ar for a maximum holding time of 0.5-10 hours to complete the fabrication of the ceramic disc with built-in heater. In other embodiments of this example, the degreased and degummed ceramic disc is sintered at a temperature of 1300°C or 1800°C for a maximum holding time of 0.5-10 hours, or it can be sintered at a temperature of 1500°C for a maximum holding time of 5 hours.

[0043] Example 2

[0044] The manufacturing process and resistance adjustment method of the built-in heater include the following steps:

[0045] S1: Design based on the target resistance value of the heater, using the following formula:

[0046] R = ρ × (L / (W × D))

[0047] In the formula: L is the heater length, W is the heater width, D is the heater thickness, and ρ is the resistivity of the heater electrode slurry;

[0048] S2: Convert the heater design values, heater length L and heater width W, into a heater design drawing;

[0049] S3: A certain amount of metal powder, 5%–30% binder, 1%–30% inorganic additive powder, 0.1%–2% dispersant, and 20%–70% organic solvent are added to a mixer according to the specified proportions and mixed evenly. After even mixing, a three-roll mill is used for rolling and dispersing to produce a metal electrode slurry with a fineness of less than 10 μm and a viscosity of 50,000–400,000 cps. By adding different proportions of inorganic powder, a resistivity of 1×10⁻⁶ can be finally produced. -6 ~1×10 -4 Heater electrode paste with Ω.cm;

[0050] S4: Convert the heater design drawing into a screen printing stencil drawing. Use 150-500 mesh, mesh diameter 15-50um, mesh thickness 20-100um, emulsion thickness 5-20um stencil making parameters to make stencils of different specifications. Different specifications of stencils can be used to make heaters with a thickness of 5-30um by screen printing.

[0051] The resistance of the heater can be calculated using the formula R = ρ × (L / (W × D)), where ρ is the metal paste, L is the length of the heating wire, W is the width of the heating wire, and D is the thickness of the heating wire. The heater electrode paste is prepared by adding different proportions of inorganic materials, such as Al2O3, AlN, SiC, and Si3N4, to create metal pastes with different resistivities ρ. Heating wires of different widths and lengths are designed, and the design drawings are made into screens for printing electrodes. Heaters of different thicknesses, lengths, and widths are then produced through screen printing. The heater is embedded within a ceramic disc, and after high-temperature sintering of the ceramic disc, heaters with different resistance values ​​are obtained. The heater design is described in [reference needed]. Figure 2 ,like Figure 2 The heater is designed with 10 heating wires, which can be individually energized and controlled to heat 10 zones. Alternatively, the 10 heating wires can be connected in parallel by adding a parallel layer for zoned control. (See reference...) Figure 2 This is one embodiment of a heater plan view;

[0052] The detailed conditions for the design and resistance adjustment of the ceramic disc built-in heater, along with the corresponding resistance values ​​and resistivity results, are shown in Table 1 below:

[0053] Table 1:

[0054]

[0055] The actual dimensions of the heater are designed based on the required resistance value and the actual size of the ceramic disc.

[0056] 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 preparing a ceramic disk with a built-in heater for an electrostatic chuck, characterized in that, include: S1: Prepare ceramic slurry, and then use the ceramic slurry to form ceramic green sheets through a casting process. The thickness of the ceramic green sheets is 200-800 μm, and the thickness difference of a single ceramic green sheet is within ±20 μm. The ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, or Si3N4. S2: The ceramic green sheet is machined to have positioning holes, interconnecting through holes, adsorption electrode holes, and heating electrode holes. S3: Add a certain amount of metal powder to a mixer, then add binder, inorganic additive powder, dispersant, and organic solvent. The metal powder can be any one of W, Mo, Mn, Ag, Pd, or Pt metal materials. Mix them evenly in the mixer according to the proportion. After mixing evenly, use a three-roll mill to roll and disperse the mixture to produce adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry with a fineness of less than 10 μm and a viscosity of 50,000 to 300,000 cps. S4: The interconnecting conductive slurry is filled into the interconnecting conductive holes of the ceramic green sheet by filling the holes. The adsorption electrode layer, heating electrode layer, parallel electrode layer and interconnecting conductive Pad are fabricated by screen printing. The thickness of the adsorption electrode layer, heating electrode layer and parallel electrode layer is 5~20um. S5: The dielectric layer, adsorption electrode layer, heating electrode layer, parallel electrode layer, interconnecting conductive pad, and green blank with adsorption electrode holes and heating electrode holes are positioned according to the product structure sequence and stacked together using a stacking machine. During stacking, the pressure is 20T to 500T, the temperature is 30℃ to 90℃, and the time is 1min to 20min, thereby producing a green ceramic disc with a heater built into the ceramic disc. S6: Place the stacked green ceramic discs in a degreasing furnace and degrease and remove the glue at a temperature of 300-550°C under an air or nitrogen atmosphere. Hold the temperature at the highest temperature for 20-120 hours to remove all organic matter from the green ceramic discs. S7: Place the degreased and degummed ceramic disc in a high-temperature sintering furnace and sinter it at a temperature of 1300-1800℃ under any one or two or more protective atmospheres of N2, H2, and Ar for 0.5-10 hours to complete the production of the ceramic disc with built-in heater.

2. The method for preparing the built-in heater ceramic disk of an electrostatic chuck according to claim 1, characterized in that, The method for manufacturing and adjusting the resistance of the built-in heater includes the following steps: S1: Design based on the target resistance value of the heater, using the following formula: R = ρ × (L / (W × D)) In the formula: L is the heater length, W is the heater width, D is the heater thickness, and ρ is the resistivity of the heater electrode slurry; S2: Convert the heater design values, heater length L and heater width W, into a heater design drawing; S3: A certain amount of metal powder, 5%–30% binder, 1%–30% inorganic additive powder, 0.1%–2% dispersant, and 20%–70% organic solvent are added to a mixer according to the specified proportions and mixed evenly. After even mixing, a three-roll mill is used for rolling and dispersing to produce a metal electrode slurry with a fineness of less than 10 μm and a viscosity of 50,000–400,000 cps. By adding different proportions of inorganic powder, a resistivity of 1×10⁻⁶ can be finally produced. -6 ~1×10 -4 Heater electrode paste with Ω.cm; S4: Convert the heater design drawing into a screen printing stencil drawing. Use 150-500 mesh, mesh diameter 15-50um, mesh thickness 20-100um, emulsion thickness 5-20um stencil making parameters to make stencils of different specifications. Different specifications of stencils can be used to make heaters with a thickness of 5-30um by screen printing.

3. The method for preparing the built-in heater ceramic disk of an electrostatic chuck according to claim 2, characterized in that, In step S3 of the fabrication and resistance adjustment method of the built-in heater, the metal powder is any one of W, Mo, Mn, Ag, Pd, and Pt metal materials, and the inorganic powder is any one of Al2O3, AlN, SiC, and Si3N4 materials.

4. The method for preparing the built-in heater ceramic disk of an electrostatic chuck according to claim 2, characterized in that, In step S3 of the fabrication and resistance adjustment method of the built-in heater, the inorganic powder is any one of Al2O3, AlN, SiC, and Si3N4 materials.

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