Preparation method of built-in heater ceramic plate of electrostatic chuck

Abstract

The invention discloses a preparation method of a built-in heater ceramic disc of an electrostatic chuck, and belongs to the technical field of electrostatic chucks. A built-in heater manufacturing and resistance adjusting method comprises the following steps that S1, according to the target resistance value of a heater, the resistance value of the built-in heater is adjusted; the design is carried out by combining the following formula: R = rho * (L / (W * D)), wherein L is the length of the heater, W is the width of the heater, D is the thickness of the heater, and rho is the resistivity of the electrode slurry of the heater; s2, converting the design value into a design drawing; s3, adding the metal powder, a binder, inorganic additive powder, a dispersant and an organic solvent into a stirrer, uniformly mixing, then rolling and dispersing to prepare metal electrode slurry with the fineness of less than 10 microns and the viscosity of 50000-400000 cps, and finally preparing heater electrode slurry with the resistivity of 1 * 10 <-6 >-1 * 10 <-4 > omega.cm by adding the inorganic powder in different proportions; and S4, converting the heater design drawing into a silk-screen printing plate drawing.

Description

Technical Field

[0001] The invention relates to the technical field of electrostatic chucks, and in particular to a method for preparing a ceramic disc with a built-in heater of an electrostatic chuck. Background Art

[0002] Generally speaking, an electrostatic chuck is made of a ceramic disk and a metal base. The ceramic disk is mostly made of a simple structure of a dielectric layer and an adsorption electrode. The built-in adsorption electrode in the ceramic disk is used to adsorb and clamp the wafer after power is turned on. The heating electrode is 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 structure electrostatic chuck has only an adsorption electrode inside the ceramic disk, and the heating electrode is attached between the ceramic disk and the metal base.

[0003] The shortcomings of the prior art are: the common structure of this type of electrostatic chuck is a ceramic disk, a heating electrode and a metal base that are assembled by bonding; during the operation of this type of electrostatic chuck, since the heating electrode is attached to the outside of the ceramic disk, the heating efficiency, heat conduction rate and temperature uniformity control will be affected by the thermal conductivity of the bonding material and the consistency of the thickness of the bonding layer, and the advantages of the excellent and uniform thermal conductivity of the ceramic disk are not fully utilized; in the process of semiconductor processing and manufacturing, when higher requirements are placed on temperature uniformity, this type of electrostatic chuck will not be able to be used normally because it cannot 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 disc with a built-in heater of an electrostatic chuck, so as 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 method for preparing a ceramic disc with a built-in heater of an electrostatic chuck, comprising:

[0007] S1: preparing a ceramic slurry, and then forming the ceramic slurry into a ceramic green sheet by a tape casting process, wherein the thickness of the ceramic green sheet is 200 to 800 um, and the thickness difference of a single ceramic green sheet is within ±20 um, and the ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4 materials;

[0008] S2: machining the ceramic green sheet into positioning holes, interconnection holes, adsorption electrode holes, and heating electrode holes by mechanical processing;

[0009] S3: Add a certain amount of metal powder into a mixer, and then add a binder, an inorganic additive powder, a dispersant, and an organic solvent, wherein the metal powder is any one of W, Mo, Mn, Ag, Pd, and Pt metal materials, and mix them evenly in the mixer according to a proportion, and after mixing evenly, use a three-roll mill to roll and disperse them, and respectively produce adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry with a fineness of less than 10um and a viscosity of 50,000 to 300,000 cps;

[0010] S4: Filling the interconnection holes of the ceramic green sheet with metal conductive slurry by hole filling, and respectively manufacturing the adsorption electrode, the heating electrode, the parallel electrode, and the interconnection conductive pad by screen printing, with the printed electrode thickness of 5 to 20 um;

[0011] S5: The dielectric layer, the adsorption electrode layer, the heating electrode layer, the parallel electrode layer, the interconnection conductive pad, and the green body processed with the adsorption electrode hole and the heating electrode hole are positioned according to the product construction sequence by using the positioning holes, and are stacked together by using a laminating machine through positioning lamination. During the lamination, the pressure is 20T to 500T, the temperature is 30℃ to 90℃, and the time is 1min to 20min, so as to produce a green body ceramic disc with the heater built inside the ceramic disc;

[0012] S6: placing the laminated green ceramic disc in a degreasing furnace, degreasing and debinding at a temperature of 300 to 550° C. in an air or nitrogen atmosphere, and maintaining the highest temperature for 20 to 120 hours to completely remove the organic matter in the green ceramic disc;

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

[0014] Preferably, the method for manufacturing the built-in heater and adjusting its resistance comprises the following steps:

[0015] S1: Design according to the target resistance value of the heater and the following formula:

[0016] R = ρ × (L / (W × D))

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

[0018] S2: Convert the heater design values ​​of heater length L and heater width W into a heater design diagram;

[0019] S3: Add a certain amount of metal powder, 5% to 30% of binder, 1% to 30% of inorganic additive powder, 0.1% to 2% of dispersant, and 20% to 70% of organic solvent into a mixer according to the proportion and mix them evenly. After mixing evenly, use a three-roll mill to roll and disperse to produce a metal electrode slurry with a fineness of less than 10um and a viscosity of 50,000 to 400,000 cps. By adding inorganic powders in different proportions, a resistivity of 1×10 -6 ~1×10 -4 Ω.cm heater electrode slurry;

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

[0021] Preferably, in step S3 of the method for making the built-in heater and adjusting its resistance, 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 the built-in heater and adjusting its resistance, 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 prepares 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 the present application embeds the heating electrode into the ceramic disk, making full use of the advantages of ceramics having excellent and uniform thermal conductivity, and can provide a ceramic disk required for an electrostatic chuck with better temperature uniformity control;

[0026] 3. The technical solution of the present application can realize multi-point and multi-zone control of the built-in heater ceramic disk by adding a parallel layer, realize multi-point and multi-zone heating of the internal heater of the ceramic disk, and maximize the requirement for uniform temperature control in the wafer processing and manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional structure diagram of an electrostatic chuck with a heater ceramic disk according to the present invention;

[0028] Figure 2 It is a plan view of the built-in heater of the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] Example 1

[0031] The main purpose of the present application is to form a ceramic disk with a heating wire built inside the ceramic disk by building a heating electrode inside the ceramic disk, making full use of the advantages of the excellent and uniform thermal conductivity of the ceramic disk, and providing an electrostatic chuck with excellent temperature uniformity in the process of wafer processing and manufacturing. At the same time, a multi-layer structure can be added inside the ceramic disk, and multi-point and multi-zone control of the built-in heating wire of the ceramic disk can be achieved by adding parallel electrodes, so as to achieve multi-point and multi-zone heating of the heater inside the ceramic disk, thereby providing more uniform temperature control for wafer processing and manufacturing;

[0032] The processing and manufacturing processes involved in this application mainly include: 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, using mechanical processing methods to process positioning holes, conductive holes, and electrode holes, stacking multiple layers, debinding and degreasing, and high-temperature sintering to form ceramic discs;

[0033] The ceramic slurry produced by ball milling is cast into a ceramic green sheet of a certain thickness by a casting process; metal electrode layers such as adsorption electrodes, heating electrodes, and parallel electrodes built into the ceramic disk are produced on the ceramic green sheet by screen printing; positioning holes, interconnection conductive holes, electrode holes, etc. for lamination are processed on the ceramic green sheet by mechanical processing; metal conductive slurry is filled into the interconnection conductive holes; after the metal electrodes and conductive layers inside the ceramic disk are processed and manufactured, they are positioned by positioning holes, and multi-layer alignment is performed by a laminating machine under certain temperature, pressure, and time conditions, so that the green layers of the ceramic disk are closely attached together, and the green ceramic disk is manufactured;

[0034] The green ceramic disc is placed in a degreasing furnace, and the organic binder in the ceramic disc is discharged under certain temperature and atmosphere conditions; the degreased ceramic disc is placed in a high-temperature sintering furnace, and the metal electrode and the ceramic layer are multi-layered and co-fired under certain temperature and atmosphere conditions to sinter the ceramic disc into porcelain, thereby producing a ceramic disc with a built-in heating electrode that meets the requirements of mechanical and electrical properties; the structure of the ceramic disc is shown in FIG. Figure 1 ;

[0035] A method for preparing a ceramic disc with a built-in heater for an electrostatic chuck comprises the following steps:

[0036] S1: preparing a ceramic slurry, and then forming the ceramic slurry into a ceramic green sheet by a tape casting process, wherein the thickness of the ceramic green sheet is 200-800um, and the thickness difference of a single ceramic green sheet is within ±20um. The ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4 materials. In other implementations of this embodiment, the thickness of the ceramic green sheet is 200um or 800um, and can also be 500um;

[0037] S2: machining the ceramic green sheet into positioning holes, interconnection vias 4, adsorption electrode holes 7, and heating electrode holes 8 by mechanical processing;

[0038] S3: Add a certain amount of metal powder into a mixer, and then add a binder, an inorganic additive powder, a dispersant, and an organic solvent, wherein the metal powder is any one of W, Mo, Mn, Ag, Pd, and Pt metal materials, and mix them evenly in the mixer according to a proportion. After mixing evenly, use a three-roller mill to roll and disperse them, and respectively produce adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry with a fineness of less than 10um and a viscosity of 50,000 to 300,000cps. The adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry are used to prepare the adsorption electrode layer 2, the heating electrode layer 3, and the parallel electrode layer 5, respectively. In other implementations of this embodiment, the viscosity of the adsorption electrode slurry, the heating electrode slurry, and the parallel electrode metal slurry can be 50,000cps or 300,000cps, the fineness is 9um, and the viscosity can also be 150,000cps;

[0039] S4: Filling the interconnection conductive hole 4 of the ceramic green sheet with metal conductive slurry by hole filling, and respectively manufacturing the adsorption electrode, the heating electrode, the parallel electrode, and the interconnection conductive Pad 6 by screen printing, wherein the thickness of the printed adsorption electrode, the heating electrode, and the parallel electrode is 5 to 20 um. In other implementations of this embodiment, the thickness of the printed adsorption electrode, the heating electrode, and the parallel electrode is 5 um or 20 um, and may also be 12 um.

[0040] S5: Reference Figure 1 , the dielectric layer 1, the adsorption electrode layer 2, the heating electrode layer 3, the parallel electrode layer 5, the interconnection conductive Pad 6 and the green body processed with the adsorption electrode hole 7 and the heating electrode hole 8 are positioned according to the product construction sequence, and are stacked together by positioning and stacking using a laminating machine. During the stacking, the pressure is 20T to 500T, the temperature is 30℃ to 90℃, and the time is 1min to 20min, so as to produce a green body ceramic disc with the heater built inside the ceramic disc. In other implementations of this embodiment, the pressure is 20T or 500T, the temperature is 30℃ or 90℃, the time is 1min or 20min, and the pressure can also be 240T, the temperature is 60℃, and the time is 10min;

[0041] S6: placing the laminated green ceramic disc in a debinding furnace, debinding and debinding at a temperature of 300 to 550° C. in an air or nitrogen atmosphere, and keeping the maximum temperature for 20 hours to 120 hours, to remove the organic matter in the green ceramic disc. In other implementations of this embodiment, debinding and debinding are carried out at a temperature of 300° C. or 550° C., and the maximum temperature is kept for 20 hours or 120 hours, or at a temperature of 420° C., and the maximum temperature is kept for 70 hours;

[0042] S7: Place the degreased and debinded ceramic disk in a high-temperature sintering furnace, and sinter it into porcelain at a temperature of 1300-1800°C for a maximum temperature of 0.5-10 hours in any one or two or more protective atmospheres of N2, H2, and Ar, to complete the production of the ceramic disk with a built-in heater. In other implementations of this embodiment, the degreased and debinded ceramic disk is sintered into porcelain at a temperature of 1300°C or 1800°C for a maximum temperature of 0.5 hours or 10 hours, or at a temperature of 1500°C for a maximum temperature of 5 hours.

[0043] Example 2

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

[0045] S1: Design according to the target resistance value of the heater and the following formula:

[0046] R = ρ × (L / (W × D))

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

[0048] S2: Convert the heater design values ​​of heater length L and heater width W into a heater design diagram;

[0049] S3: Add a certain amount of metal powder, 5% to 30% of binder, 1% to 30% of inorganic additive powder, 0.1% to 2% of dispersant, and 20% to 70% of organic solvent into a mixer according to the proportion and mix them evenly. After mixing evenly, use a three-roll mill to roll and disperse to produce a metal electrode slurry with a fineness of less than 10um and a viscosity of 50,000 to 400,000 cps. By adding inorganic powders in different proportions, a resistivity of 1×10 -6 ~1×10 -4 Ω.cm heater electrode slurry;

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

[0051] The resistance of the heater can be calculated by 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 inorganic materials in different proportions. The inorganic powder can be any one of Al2O3, AlN, SiC, Si3N4 and other materials to prepare 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 made by screen printing; the heater is built-in and laminated inside the ceramic disk, and after the ceramic disk is sintered at high temperature, heaters with different resistance values ​​can be obtained; the design of the heater is shown in Figure 2 ,like Figure 2 The heater is designed with 10 heating wires, which can be powered on individually to control the heating in 10 zones. You can also add parallel layers to connect the 10 heating wires in parallel for zone control. Figure 2 , is an embodiment of a plan view of a heater;

[0052] The detailed conditions of the ceramic disk built-in heater design and resistance adjustment specific embodiment, as well as the corresponding resistance value and resistivity results are shown in Table 1 below:

[0053] Table 1:

[0054]

[0055] The actual size of the heater is designed according to the required resistance value and the actual size of the ceramic disk.

[0056] 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 method for preparing a ceramic disc with a built-in heater for an electrostatic chuck, characterized in that: include: S1: preparing a ceramic slurry, and then forming the ceramic slurry into a ceramic green sheet by a tape casting process, wherein the thickness of the ceramic green sheet is 200 to 800 um, and the thickness difference of a single ceramic green sheet is within ±20 um, and the ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4 materials; S2: machining the ceramic green sheet into positioning holes, interconnection holes, adsorption electrode holes, and heating electrode holes by mechanical processing; S3: Add a certain amount of metal powder into a mixer, and then add a binder, an inorganic additive powder, a dispersant, and an organic solvent, wherein the metal powder is any one of W, Mo, Mn, Ag, Pd, and Pt metal materials, and mix them evenly in the mixer according to a proportion, and after mixing evenly, use a three-roll mill to roll and disperse them, and respectively produce adsorption electrode slurry, heating electrode slurry, and parallel electrode metal slurry with a fineness of less than 10um and a viscosity of 50,000 to 300,000 cps; S4: Filling the interconnection holes of the ceramic green sheet with metal conductive slurry by hole filling, and respectively manufacturing the adsorption electrode, the heating electrode, the parallel electrode, and the interconnection conductive pad by screen printing, with the printed electrode thickness of 5 to 20 um; S5: The dielectric layer, the adsorption electrode layer, the heating electrode layer, the parallel electrode layer, the interconnection conductive pad, and the green body processed with the adsorption electrode hole and the heating electrode hole are positioned according to the product construction sequence by using the positioning holes, and are stacked together by using a laminating machine through positioning lamination. During the lamination, the pressure is 20T to 500T, the temperature is 30℃ to 90℃, and the time is 1min to 20min, so as to produce a green body ceramic disc with the heater built inside the ceramic disc; S6: placing the laminated green ceramic disc in a degreasing furnace, degreasing and debinding at a temperature of 300 to 550° C. in an air or nitrogen atmosphere, and maintaining the highest temperature for 20 to 120 hours to completely remove the organic matter in the green ceramic disc; S7: Place the degreased and debinded ceramic disc in a high-temperature sintering furnace, and sinter it into porcelain at a temperature of 1300 to 1800°C for 0.5 to 10 hours in a protective atmosphere of any one of N2, H2, and Ar, or two or more of them, to complete the production of the ceramic disc with a built-in heater.

2. The method for preparing a ceramic disc with a built-in heater for an electrostatic chuck according to claim 1, characterized in that: The method for manufacturing the built-in heater and adjusting its resistance comprises the following steps: S1: Design according to the target resistance value of the heater and the following formula: R = ρ × (L / (W × D)) Where: L is the heater length, W is the heater width, D is the heater thickness, and ρ is the resistivity of the heater electrode paste; S2: Convert the heater design values ​​of heater length L and heater width W into a heater design diagram; S3: Add a certain amount of metal powder, 5% to 30% of binder, 1% to 30% of inorganic additive powder, 0.1% to 2% of dispersant, and 20% to 70% of organic solvent into a mixer according to the proportion and mix them evenly. After mixing evenly, use a three-roll mill to roll and disperse to produce a metal electrode slurry with a fineness of less than 10um and a viscosity of 50,000 to 400,000 cps. By adding inorganic powders in different proportions, a resistivity of 1×10 -6 ~1×10 -4 Ω.cm heater electrode slurry; S4: Convert the heater design drawing into a screen printing screen drawing, use 150-500 mesh, mesh diameter 15-50um, mesh thickness 20-100um, emulsion thickness 5-20um screen making parameters to make screens of different specifications, and screens of different specifications can be used to make heaters with a thickness of 5-30um by screen printing.

3. The method for preparing a ceramic disc with a built-in heater for an electrostatic chuck according to claim 2, characterized in that: In step S3 of the method for making the built-in heater and adjusting its resistance, 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 a ceramic disc with a built-in heater for an electrostatic chuck according to claim 2, characterized in that: In step S3 of the method for manufacturing the built-in heater and adjusting its resistance, the inorganic powder is any one of Al2O3, AlN, SiC, and Si3N4 materials.

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