An electrostatic chuck and its preparation method

Abstract

This invention relates to the field of semiconductor manufacturing technology, and more particularly to an electrostatic chuck and its preparation method. The electrostatic chuck provided by this invention includes a base, a dielectric layer, an insulating layer, and conductive electrodes. The insulating layer and dielectric layer are disposed on the base from bottom to top, and the conductive electrodes are disposed within the dielectric layer. The conductive electrodes are made of a titanium-containing tungsten alloy, wherein the titanium content in the conductive electrodes is 5-20% by mass. The electrostatic chuck provided by this invention combines high density, excellent electrode-ceramic interface bonding strength, high electrostatic adsorption force, and sub-second rapid response capability, effectively avoiding defects such as microcracks, and greatly improving the overall performance, reliability, and service life of the product.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to an electrostatic chuck and its preparation method. Background Technology

[0002] Electrostatic chucks (ESCs) are key components in semiconductor manufacturing processes, widely used in various vacuum and plasma processes such as dry etching, chemical vapor deposition, physical vapor deposition, and ion implantation. Their primary function is to generate electrostatic attraction by applying voltage to internal electrodes, thereby smoothly and firmly fixing semiconductor wafers onto the chuck surface to ensure precision and stability during processing.

[0003] A typical electrostatic chuck structure mainly consists of a ceramic substrate (containing a dielectric layer and an insulating layer) and conductive electrodes embedded within the ceramic substrate. For material selection, alumina ceramic is typically used as both the dielectric layer and the substrate material, with high-melting-point metals such as tungsten or molybdenum embedded as conductive electrodes. This structure usually requires a single-stage sintering process using high-temperature co-firing.

[0004] However, in the existing technology, there are a series of technical challenges in the process of sintering metal electrodes and ceramic substrates together (i.e., co-firing), mainly in the following aspects: (1) The problem of sintering densification of electrode materials: Pure tungsten, the main material of the electrode, has an extremely high melting point (about 3300℃), making it difficult to achieve complete densification at the conventional co-firing temperature with alumina ceramics. This results in a large number of pores remaining inside the sintered tungsten electrode, leading to low density. This porous structure not only reduces the conductivity of the electrode and affects the response speed and uniformity of electrostatic adsorption, but may also become a source of adsorption and release of pollutants. Although existing technologies have attempted to promote the densification of tungsten by adding oxide sintering aids, the effect is limited and may introduce impurities.

[0005] (2) Thermomechanical mismatch problem: There is a significant difference in the coefficient of thermal expansion (CTE) between pure tungsten and alumina ceramics (pure tungsten is approximately 4.5 × 10⁻⁶). -6 / K, alumina ceramics have a strength of approximately 7.0-8.0 × 10⁻⁶. -6 / K). During the cooling process after high-temperature co-firing, this mismatch will generate huge thermal stress at the interface between the electrode and the ceramic. This stress can lead to a decrease in interfacial bonding strength, or even cause microcracks or delamination, seriously affecting the long-term reliability and service life of the electrostatic chuck.

[0006] (3) The contradiction of process temperature: In order to improve the corrosion resistance of electrostatic chucks in plasma environment, high-purity alumina ceramics are usually required. However, high-purity alumina ceramics require a high sintering temperature to obtain excellent performance, but this will aggravate the above-mentioned thermal stress problem and may lead to abnormal growth of ceramic grains, affecting the dimensional accuracy and mechanical properties of the product. If the sintering temperature is lowered to accommodate the electrode, the densification and performance of the high-purity ceramic matrix cannot be guaranteed.

[0007] Therefore, there is an urgent need for a new technical solution to address the densification and thermomechanical compatibility issues between electrode materials and ceramic substrates under low-temperature co-firing conditions during the manufacturing process of electrostatic chucks. This would allow for the improvement of electrode conductivity and interfacial bonding reliability while ensuring the performance of high-purity ceramics. Summary of the Invention

[0008] This invention provides an electrostatic chuck and its preparation method to solve the above-mentioned problems existing in the prior art.

[0009] According to a first aspect of the present invention, an electrostatic chuck is provided, comprising a base, a dielectric layer, an insulating layer, and a conductive electrode. The insulating layer and the dielectric layer are disposed on the base from bottom to top, and the conductive electrode is disposed within the dielectric layer. The conductive electrode is made of a titanium-containing tungsten alloy, wherein the mass content of titanium in the conductive electrode is 5-20%.

[0010] The electrostatic chuck provided by this invention uses a tungsten-titanium (W-Ti) solid solution alloy as an embedded conductive electrode. Titanium (Ti) can be used as an active sintering aid and a coefficient of thermal expansion regulator, which solves the problem that pure tungsten electrodes are difficult to densify at the sintering temperature of alumina ceramics (conventionally >1600℃) due to their extremely high melting point. This allows the conductive electrode to achieve full densification at a lower temperature of 1250-1450℃.

[0011] According to the electrostatic chuck of the present invention, the conductive electrode is prepared from raw materials containing tungsten powder and titanium powder, wherein the purity of the tungsten powder is ≥99.999%, and the particle size D50 is 1-5 μm; the purity of the titanium powder is ≥99.9%, and the particle size D50 is 1-20 μm; and the density of the conductive electrode is ≥99.5%. High-purity raw materials avoid the negative impact of impurities on electrical performance, while high density ensures the integrity of the conductive pathway of the electrode, avoiding performance degradation or contamination problems caused by pores.

[0012] According to the electrostatic chuck of the present invention, the resistivity of the conductive electrode is ≤20μΩcm (preferably 5-15μΩcm); the thickness of the conductive electrode is 5-30μm, and the electrode pattern is unipolar, bipolar, or multipolar.

[0013] The present invention's limitation on the low resistivity of the conductive electrode ensures that the electrode can transfer charge quickly and efficiently, thereby achieving a rapid electrostatic adsorption / desorption response and improving production efficiency. The limitation on the thickness of the conductive electrode optimizes the electrode size while ensuring sufficient conductivity, thus balancing the overall mechanical and thermal properties of the chuck.

[0014] According to the electrostatic chuck of the present invention, the dielectric layer includes a first dielectric layer and a second dielectric layer, the first dielectric layer is in contact with the wafer, the second dielectric layer is connected to the insulating layer, and the conductive electrode is disposed in the second dielectric layer; Preferably, the first dielectric layer is made of high-purity alumina with a mass percentage of ≥99.99%; Preferably, the second dielectric layer is prepared from raw materials including dielectric layer alumina composite powder; in the dielectric layer alumina composite powder, the mass percentage of alumina is ≥96% (preferably 96%-99%); more preferably, the dielectric layer alumina composite powder further includes a dielectric layer sintering aid, the mass percentage of the dielectric layer sintering aid is ≤4% (preferably 1%-4%); the dielectric layer sintering aid is selected from one or more of calcium oxide, magnesium oxide, silicon oxide, and iron oxide. This invention introduces a gradient dielectric layer structure, achieving regional optimization of performance. By dividing the dielectric layer into a high-purity (≥99.99%) alumina layer that directly contacts the wafer and an alumina layer containing sintering aid (≥96%) near the electrode, an effective balance between plasma corrosion resistance and low-temperature co-firing performance is achieved. The high-purity layer provides excellent dielectric properties and corrosion resistance, protecting the wafer from contamination; while the layer containing sintering aids can better co-sinter with the tungsten-titanium electrode at a lower temperature, enhancing the interfacial bonding between the electrode and the dielectric layer.

[0015] In some specific embodiments, the first dielectric layer is formed by dry pressing to form a blank, followed by sintering.

[0016] In some specific embodiments, the second dielectric layer is formed by first preparing an alumina slurry from raw materials including dielectric layer alumina composite powder, then casting / printing, and finally sintering. The composition of the alumina slurry, by weight, is as follows: 100 parts dielectric layer alumina composite powder, 1-10 parts organic binder (e.g., PVA), 0.1-2 parts plasticizer (e.g., DBP), 0.1-2 parts dispersant (e.g., SC0505K), and 30-80 parts organic solvent (e.g., ethanol).

[0017] Preferably, the thickness of the first insulating layer and the second dielectric layer is independently 10-100 μm.

[0018] According to the electrostatic chuck of the present invention, the insulating layer includes a first insulating layer and a second insulating layer, the first insulating layer is connected to the second dielectric layer of the dielectric layer, and the second insulating layer is connected to the base through a bonding layer; Preferably, the second insulating layer is made of high-purity alumina with a mass percentage of ≥99.99%.

[0019] In some specific embodiments, the second insulating layer is formed by dry pressing to form a blank, followed by sintering.

[0020] Preferably, the first insulating layer is prepared from raw materials including insulating layer alumina composite powder; in the insulating layer alumina composite powder, the mass percentage of alumina is ≥96% (preferably 96%-99%); more preferably, the insulating layer alumina composite powder further includes an insulating layer sintering aid, the mass percentage of the insulating layer sintering aid is ≤4% (preferably 1%-4%); the insulating layer sintering aid is selected from one or more of calcium oxide, magnesium oxide, silicon oxide and iron oxide.

[0021] This invention introduces a gradient insulation structure. By setting a first insulating layer containing sintering aids near the electrodes and a high-purity second insulating layer near the base, the compatibility and bonding strength between different material layers inside the electrostatic chuck are optimized. The first insulating layer containing sintering aids ensures its sintering compatibility with the dielectric and electrode layers, while the high-purity second insulating layer guarantees excellent insulation performance and structural support for the base. Overall, this further reduces internal stress and improves the overall stability and service life of the product.

[0022] In some specific embodiments, the first insulating layer is formed by first preparing an alumina slurry from raw materials including insulating alumina composite powder, then casting / printing, and finally sintering. The composition of the alumina slurry, by weight, is as follows: 100 parts insulating alumina composite powder, 1-10 parts organic binder (e.g., PVA), 0.1-2 parts plasticizer (e.g., DBP), 0.1-2 parts dispersant (e.g., SC0505K), and 30-80 parts organic solvent (e.g., ethanol).

[0023] Preferably, the thickness of the insulating layer is 600-2800 μm, wherein the thickness of the first insulating layer is 10-100 μm and the thickness of the second insulating layer is 500-2700 μm.

[0024] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-described electrostatic chuck, comprising the following steps: Prepare an insulating layer preform, a dielectric layer preform, and a conductive electrode paste; embed the conductive electrode paste into the dielectric layer preform; The insulating layer blank and the dielectric layer blank filled with the conductive electrode slurry are sequentially stacked on the base to form an electrostatic chuck blank; The electrostatic chuck blank is sintered by pressure sintering at a temperature of 1250-1450℃ and a pressure of 10-100 MPa.

[0025] The electrostatic chuck preparation method provided by the present invention adopts pressure sintering (such as hot pressing sintering or spark plasma sintering) method. By applying an axial pressure of 10-100 MPa and controlling the sintering temperature at 1250-1450℃, the densification process of alumina ceramic and tungsten titanium electrode at low temperature is greatly promoted, abnormal grain growth is avoided, and the uniformity and high density of microstructure are ensured.

[0026] According to the method for preparing the electrostatic chuck of the present invention, the sintering time is 5-24 hours; the sintering atmosphere is argon atmosphere, and the gas flow rate is 5-30 L / min.

[0027] According to the method for preparing the electrostatic chuck of the present invention, the conductive electrode paste comprises, by weight, 80-95 parts of tungsten powder, 5-20 parts of titanium powder, 5-30 parts of organic carrier, and 8-10 parts of solvent; the organic carrier is selected from one or more of ethyl cellulose, acrylic acid, and polyvinyl butyral; the solvent is terpineol.

[0028] According to the method for preparing an electrostatic chuck of the present invention, the electrostatic chuck blank is degreased at 500-700°C and then sintered.

[0029] This invention employs a degreasing pretreatment at 500-700℃ to ensure complete and residue-free removal of organic carriers from the slurry before the main sintering stage. This prevents organic matter from carbonizing at high temperatures and remaining inside the ceramic, thus preventing defects such as blackening, porosity, and decreased insulation performance caused by residual carbon, and significantly improving the density and purity of the final product.

[0030] According to the method for preparing an electrostatic chuck of the present invention, when the dielectric layer comprises a first dielectric layer and a second dielectric layer, and the insulating layer comprises a first insulating layer and a second insulating layer, the method for preparing the electrostatic chuck includes the following steps: Prepare a first insulating layer blank, a second insulating layer blank, a first dielectric layer blank, a second dielectric layer blank, and a conductive electrode paste; The second insulating layer blank, the first insulating layer blank, and the second dielectric layer blank are stacked sequentially on the base. The conductive electrode paste is printed on the second dielectric layer blank. Then, the first dielectric layer blank is covered on the second dielectric layer blank printed with the conductive electrode paste to form an electrostatic chuck blank. The electrostatic chuck blank is sintered using a pressure sintering method at a temperature of 1250-1450℃ and a pressure of 10-100 MPa. Preferably, the electrostatic chuck blank is first debonded at 500℃-700℃ and then sintered again using a pressure sintering method.

[0031] Preferably, the raw materials used to prepare the second insulating layer blank and the first dielectric layer blank are the same; the raw materials used to prepare the first insulating layer blank and the second dielectric layer blank are the same.

[0032] More preferably, the method for preparing the first dielectric layer blank is as follows: alumina powder with a purity ≥99.99% is pressed into a blank sheet by dry pressing at a pressure of 150-250MPa; the blank sheet is then placed in an air atmosphere and heated to 500-700℃ at a rate of 0.5-1.5℃ / min and held at that temperature for 1-3 hours; subsequently, it is pre-fired at 1000-1300℃ for 1-2 hours.

[0033] The method for preparing the second dielectric layer blank is as follows: the alumina composite powder is mixed with an organic binder, plasticizer, dispersant and organic solvent, and ball-milled to obtain an alumina slurry; the obtained alumina slurry is dried; the alumina composite powder comprises 96-99 parts of alumina base powder and 1-4 parts of dielectric layer sintering aid by weight.

[0034] The beneficial effects of this invention are: This invention creatively employs a tungsten-titanium alloy as the conductive electrode material, combined with pressure sintering and a gradient ceramic layer design, successfully solving two major technical challenges in the low-temperature co-firing process of traditional pure tungsten electrodes and alumina ceramics: thermomechanical mismatch and densification difficulties. The addition of titanium optimizes the electrode's coefficient of thermal expansion to match the ceramic, significantly reducing interfacial thermal stress. Simultaneously, titanium acts as an active sintering aid, enabling the electrode and ceramic to achieve high densification simultaneously at lower temperatures. The electrostatic chuck provided by this invention combines high density, excellent electrode-ceramic interfacial bonding strength, high electrostatic adsorption force, and sub-second rapid response capability, effectively avoiding defects such as microcracks and greatly improving the product's overall performance, reliability, and service life. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1This is a schematic diagram of the electrostatic chuck provided in Embodiment 1 of the present invention.

[0037] Figure 2 This is the phase diagram of the W-Ti alloy.

[0038] Figure 3 This is a microscopic morphology diagram of the conductive electrode in the electrostatic chuck provided in Embodiment 1 of the present invention.

[0039] Figure 4 This is a microscopic morphology diagram of the conductive electrode in the electrostatic chuck provided in Comparative Example 1 of the present invention.

[0040] Reference numerals: 110, first dielectric layer; 120, second dielectric layer; 130, conductive electrode; 140, first insulating layer; 150, second insulating layer; 160, bonding layer; 170, base. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] The raw materials used in the following examples are shown in Table 1 below.

[0043] Table 1 Material type Purity requirements Particle size requirement (D50) Phase / Other Requirements Pretreatment process High-purity alumina powder (for 99.99% layer) ≥ 99.99% 0.1-0.5μm α phase ≥ 95% Ball milling and sand milling to the target particle size, followed by spray granulation into 60-200μm spherical powder. Alumina-based powder (for 96% layer) <![CDATA[Al2O3≥ 99.99% (purity before mixing)]]> 0.1-0.5μm α phase ≥ 95% Mix with sintering aids in high-energy ball milling for more than 24 hours. <![CDATA[Sintering aids (CaO, MgO, SiO2 and Fe2O3 with a weight ratio of 1:1:1:1)]]> ≥ 99.9% 0.05-0.2μm - As an additive, it is blended with alumina-based powder. Tungsten powder (W) ≥ 99.999% 1.0-5.0μm - Ball milling and mixing with titanium powder in a high-purity organic solvent Titanium powder (Ti) ≥ 99.9% 5.0-20.0μm - Ball milling and mixing with tungsten powder in a high-purity organic solvent Example 1 This embodiment provides a bipolar electrostatic chuck for 12-inch silicon wafers, such as... Figure 1 As shown, the electrostatic chuck includes a base 170, a bonding layer 160, a second insulating layer 150, a first insulating layer 140, a conductive electrode 130, a second dielectric layer 120, and a first dielectric layer 110. The bonding layer 160, second insulating layer 150, first insulating layer 140, second dielectric layer 120, and first dielectric layer 110 are disposed on the base 170 from bottom to top. The conductive electrode 130 is disposed within the second dielectric layer 120. The thicknesses of the first dielectric layer 110, second dielectric layer 120, first insulating layer 140, and second insulating layer 150 are 300 μm, 10 μm, 10 μm, and 600 μm, respectively.

[0044] This embodiment also provides a method for preparing the electrostatic chuck, including the following steps: (1) Blank forming and pretreatment: High-purity alumina powder with a purity of ≥99.99% obtained by spray granulation is pressed into blanks with a thickness of 500μm and 1000μm under a pressure of 200MPa by dry pressing, which serve as blanks for the first dielectric layer 110 and the second insulating layer 150.

[0045] The above-mentioned raw blanks were placed in an air atmosphere furnace and heated to 600℃ at a rate of 1℃ / min and held for 2 hours to complete degreasing. Subsequently, they were pre-fired at 1150℃ for 1 hour to obtain a certain mechanical strength (density ≥70%).

[0046] (2) Slurry preparation and casting / printing: Preparation of 96% alumina slurry: 10,000g of pretreated alumina composite powder (the mass ratio of alumina base powder to sintering aid is 96:4) is mixed with 500g of PVA organic binder, 100g of DBP plasticizer, 100g of SC0505K dispersant and 5,000g of ethanol organic solvent, and ball-milled to prepare a uniform casting slurry. Preparation of tungsten-titanium electrode slurry: 1,000g of tungsten powder and 150g of titanium powder, 250g of organic carrier (ethyl cellulose) and 100g of solvent (terpineol) are mixed and rolled into a uniform mixture using a three-roll mill to prepare a conductive slurry.

[0047] (3) Printing and Lamination: On the surface of the pre-fired and processed second insulating layer 150 blank, a layer of 96% alumina paste is uniformly printed using screen printing technology. After drying, it forms the first insulating layer 140 blank. On the first insulating layer 140 blank, a tungsten-titanium electrode paste with a pre-designed pattern is screen printed to form a conductive electrode layer with a thickness of about 15 μm. On the conductive electrode layer, 96% alumina paste is printed to form the second dielectric layer 120 blank. Finally, the pre-fired first dielectric layer 110 blank is attached to the top layer.

[0048] (4) Low-temperature pressure sintering: The stacked chuck blanks are placed in a mold, and the adhesive is removed at 600℃. After removal, the blanks are placed in a hot-press sintering furnace. Sintering process: Under an argon atmosphere (flow rate 15 L / min), the temperature is increased to 1350℃ at a rate of 10℃ / min, an axial pressure of 30 MPa is applied, and the temperature is held for 8 hours. After sintering, the blanks are cooled to room temperature in the furnace. The sintered body is then subjected to planar grinding and external machining to achieve the final dimensional requirements.

[0049] The product performance test results are as follows: Electrostatic chuck density: ≥99.7% (Archimedes displacement method).

[0050] The W-Ti alloy phase diagram in the tungsten-titanium electrode layer is as follows: Figure 2 As shown. Microstructure of the tungsten-titanium electrode layer (SEM observation): as follows. Figure 3As shown, there are no obvious pores, the bonding with the ceramic interface is tight, and titanium is uniformly dissolved in tungsten. The resistivity of the conductive electrode is 15 μΩcm.

[0051] Electrostatic adsorption performance: When a DC voltage of 3000V is applied, the adsorption force on a 12-inch silicon wafer is >25Torr, and the adsorption / desorption response time is <0.8 seconds.

[0052] Example 2 This embodiment provides a bipolar electrostatic chuck for 12-inch silicon wafers, which differs from Embodiment 1 in that the titanium content in the conductive electrode is 10wt% and the thickness of the conductive electrode is 25μm.

[0053] This embodiment also provides a method for preparing the electrostatic chuck, which differs from Embodiment 1 in that the sintering temperature is increased to 1400℃, the pressure is increased to 50MPa, and the holding time is shortened to 5h.

[0054] The performance results of the electrostatic chuck are as follows: The electrostatic chuck has a density ≥99.9%. Due to the thicker electrodes and more complete sintering, the electrode sheet resistance is further reduced. The resistivity of the conductive electrodes is 10 μΩcm. At the same 3000V voltage, the adsorption force increases to >35 Torr, while the response time remains <1.0 second.

[0055] Example 3 This embodiment provides a bipolar electrostatic chuck for 12-inch silicon wafers, which differs from Embodiment 1 in that the titanium content in the conductive electrode is 5wt%.

[0056] This embodiment also provides a method for preparing the electrostatic chuck, which differs from Embodiment 1 in that: All alumina powders had a D50 controlled within a narrow range of 0.1-0.2 μm to increase sintering activity. The sintering temperature was set at 1400℃, the pressure at 20 MPa, and the holding time was 12 h.

[0057] The performance results of the electrostatic chuck are as follows: Electrostatic chuck density: ≥99.5%.

[0058] Thanks to finer ceramic grains and more conductive electrodes, the resistivity of the conductive electrodes is 7 μΩcm. The electrostatic chuck exhibits extremely fast response characteristics, with an adsorption / desorption response time of <0.5 seconds, while the adsorption force is maintained at >20 Torr (3000V).

[0059] Example 4 This embodiment provides a bipolar electrostatic chuck for 12-inch silicon wafers, which differs from Embodiment 1 in that the titanium content in the conductive electrode is 20wt%.

[0060] This embodiment also provides a method for preparing the electrostatic chuck, which differs from Embodiment 1 in that: The D50 of all alumina powders was controlled within a narrow range of 0.1-0.2 μm to increase sintering activity. The sintering temperature was set at 1300℃, the pressure at 20 MPa, and the holding time was 12 h.

[0061] The performance results of the electrostatic chuck are as follows: Electrostatic chuck density: ≥99.6%.

[0062] Thanks to finer ceramic grains and more conductive electrodes, the resistivity of the conductive electrodes is 15 μΩcm. The electrostatic chuck exhibits extremely fast response characteristics, with an adsorption / desorption response time of <0.7 seconds, while the adsorption force is maintained at >18 Torr (3000V).

[0063] Comparative Example 1 This comparative example provides a bipolar electrostatic chuck for 12-inch silicon wafers, which differs from Example 1 in that the conductive electrode material is pure tungsten and does not include titanium.

[0064] This comparative example also provides a method for preparing the electrostatic chuck. The difference from Example 1 is that, except that the titanium powder in the conductive paste is replaced with tungsten powder, the other steps and parameters are the same as in Example 1.

[0065] After sintering at 1450℃, 30MPa pressure, and holding time for 8 hours, as follows: Figure 4 As shown, SEM observation revealed numerous unclosed pores within the pure tungsten electrode layer, indicating a very low degree of densification, and microcracks were present at the electrode-ceramic interface. Performance testing indicated that its adsorption force was unstable, and the response time fluctuated significantly (>10 seconds), failing to meet the application requirements.

[0066] Comparative Example 2 This comparative example provides a bipolar electrostatic chuck for 12-inch silicon wafers, which differs from Example 1 in that the conductive electrode material is mainly composed of tungsten and contains 2% titanium.

[0067] This comparative example also provides a method for preparing the electrostatic chuck. The difference from Example 1 is that, except for replacing the conductive electrode material with tungsten-2% titanium, the other steps and parameters are the same as in Example 1.

[0068] After sintering at 1300℃, 20 MPa, and for 12 hours, SEM observation revealed numerous unclosed pores within the pure tungsten electrode layer, indicating low densification, and microcracks at the electrode-ceramic interface. Performance testing showed unstable adsorption capacity and large fluctuations in response time (>15 seconds), failing to meet application requirements.

[0069] Comparative Example 3 This comparative example provides a bipolar electrostatic chuck for 12-inch silicon wafers, which differs from Example 1 in that the conductive electrode material is mainly composed of tungsten and has a titanium content of 25%.

[0070] This comparative example also provides a method for preparing the electrostatic chuck. The difference from Example 1 is that, except for replacing the conductive electrode material with tungsten-25% titanium, the other steps and parameters are the same as in Example 1.

[0071] After sintering at 1300℃, 20 MPa, and for 12 hours, titanium undergoes extensive migration and oxidation, resulting in excessively high resistivity (30 μΩcm).

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrostatic chuck, characterized in that, The device includes a base, a dielectric layer, an insulating layer, and a conductive electrode. The insulating layer and the dielectric layer are disposed on the base from bottom to top, and the conductive electrode is disposed within the dielectric layer. The conductive electrode is made of a titanium-containing tungsten alloy, wherein the mass content of titanium in the conductive electrode is 5-20%.

2. The electrostatic chuck according to claim 1, characterized in that, The conductive electrode is prepared from raw materials containing tungsten powder and titanium powder, wherein the purity of the tungsten powder is ≥99.999% and the particle size D50 is 1-5μm; the purity of the titanium powder is ≥99.9% and the particle size D50 is 1-20μm; and the density of the conductive electrode is ≥99.5%.

3. The electrostatic chuck according to claim 1 or 2, characterized in that, The resistivity of the conductive electrode is ≤20μΩcm; the thickness of the conductive electrode is 5-30μm, and the electrode pattern is unipolar, bipolar, or multipolar.

4. The electrostatic chuck according to any one of claims 1-3, characterized in that, The dielectric layer includes a first dielectric layer and a second dielectric layer. The first dielectric layer is in contact with the wafer, and the second dielectric layer is connected to the insulating layer. The conductive electrode is disposed in the second dielectric layer. Preferably, the first dielectric layer is made of high-purity alumina with a mass percentage of ≥99.99%; Preferably, the second dielectric layer is prepared from raw materials including dielectric layer alumina composite powder; wherein the mass percentage of alumina in the dielectric layer alumina composite powder is ≥96%; more preferably, the dielectric layer alumina composite powder further includes a dielectric layer sintering aid, wherein the mass percentage of the dielectric layer sintering aid is ≤4%; wherein the dielectric layer sintering aid is selected from one or more of calcium oxide, magnesium oxide, silicon oxide and iron oxide; Preferably, the thickness of the first insulating layer and the second dielectric layer is independently 10-100 μm.

5. The electrostatic chuck according to any one of claims 1-4, characterized in that, The insulating layer includes a first insulating layer and a second insulating layer. The first insulating layer is connected to the second dielectric layer of the dielectric layer, and the second insulating layer is connected to the base through a bonding layer. Preferably, the second insulating layer is made of high-purity alumina with a mass percentage of ≥99.99%; Preferably, the first insulating layer is prepared from raw materials including insulating layer alumina composite powder; wherein the mass percentage of alumina in the insulating layer alumina composite powder is ≥96%; more preferably, the insulating layer alumina composite powder further includes an insulating layer sintering aid, wherein the mass percentage of the insulating layer sintering aid is ≤4%; wherein the insulating layer sintering aid is selected from one or more of calcium oxide, magnesium oxide, silicon oxide and iron oxide; Preferably, the thickness of the insulating layer is 600-2800 μm, wherein the thickness of the first insulating layer is 10-100 μm and the thickness of the second insulating layer is 500-2700 μm.

6. The method for preparing the electrostatic chuck according to any one of claims 1-5, characterized in that, Includes the following steps: Prepare an insulating layer preform, a dielectric layer preform, and a conductive electrode paste; embed the conductive electrode paste into the dielectric layer preform; The insulating layer blank and the dielectric layer blank filled with the conductive electrode slurry are sequentially stacked on the base to form an electrostatic chuck blank; The electrostatic chuck blank is sintered by pressure sintering at a temperature of 1250-1450℃ and a pressure of 10-100 MPa.

7. The method for preparing an electrostatic chuck according to claim 6, characterized in that, The sintering time is 5-24 hours; the sintering atmosphere is argon atmosphere, and the gas flow rate is 5-30 L / min.

8. The method for preparing an electrostatic chuck according to claim 6 or 7, characterized in that, The conductive electrode paste comprises, by weight, 80-95 parts tungsten powder, 5-20 parts titanium powder, 5-30 parts organic carrier, and 8-10 parts solvent; the organic carrier is selected from one or more of ethyl cellulose, acrylic acid, and polyvinyl butyral; and the solvent is terpineol.

9. The method for preparing an electrostatic chuck according to any one of claims 6-8, characterized in that, The electrostatic chuck blank is degreased at 500-700℃ and then sintered.

10. The method for preparing an electrostatic chuck according to any one of claims 6-9, characterized in that, When the dielectric layer comprises a first dielectric layer and a second dielectric layer, and the insulating layer comprises a first insulating layer and a second insulating layer, the method for preparing the electrostatic chuck includes the following steps: Prepare a first insulating layer blank, a second insulating layer blank, a first dielectric layer blank, a second dielectric layer blank, and a conductive electrode paste; The second insulating layer blank, the first insulating layer blank, and the second dielectric layer blank are stacked sequentially on the base. The conductive electrode paste is printed on the second dielectric layer blank. Then, the first dielectric layer blank is covered on the second dielectric layer blank printed with the conductive electrode paste to form an electrostatic chuck blank. The electrostatic chuck blank is sintered by pressure sintering at a temperature of 1250-1450℃ and a pressure of 10-100 MPa. Preferably, the raw materials used to prepare the second insulating layer blank and the first dielectric layer blank are the same; the raw materials used to prepare the first insulating layer blank and the second dielectric layer blank are the same. More preferably, the method for preparing the first dielectric layer blank is as follows: alumina powder with a purity ≥99.99% is pressed into a blank sheet by dry pressing at a pressure of 150-250MPa; the blank sheet is then placed in an air atmosphere and heated to 500-700℃ at a rate of 0.5-1.5℃ / min and held at that temperature for 1-3 hours; subsequently, it is pre-fired at 1000-1300℃ for 1-2 hours. The method for preparing the second dielectric layer blank is as follows: the alumina composite powder is mixed with an organic binder, plasticizer, dispersant and organic solvent, and ball-milled to obtain an alumina slurry; the obtained alumina slurry is dried; the alumina composite powder comprises 96-99 parts of alumina base powder and 1-4 parts of dielectric layer sintering aid by weight.

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