An aluminum nitride electrostatic chuck and its preparation method

Abstract

This invention relates to aluminum nitride electrostatic chucks, aluminum nitride electrostatic chucks with different functional ceramic layers, and their preparation methods. The aluminum nitride electrostatic chuck of this invention uses a three-layer progressive hydraulic pressing, cold isostatic pressing, and integral sintering molding process, resulting in better flatness and parallelism, thereby improving the uniformity of electrostatic adsorption force or temperature control performance. The aluminum nitride electrostatic chuck of this invention with different functional ceramic layers includes a first ceramic layer, an electrostatic electrode, a second ceramic layer, a heating electrode, and a third ceramic layer. The electrostatic electrode is located between the first and second ceramic layers, and the heating electrode is located between the second and third ceramic layers. The composition and content of the first, second, and third ceramic layers are all different. After integral sintering, each ceramic layer has different chemical composition, crystal phase composition, and thermal and electrical properties, thus achieving different functional focuses for each ceramic layer.

Description

Technical Field

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

[0002] An electrostatic chuck is a widely used silicon wafer clamping tool in the modern semiconductor industry, which uses electrostatic attraction to hold silicon wafers in place. Electrostatic chucks avoid the irreparable damage to silicon wafers caused by pressure, impact, and other mechanical factors during use, as is common with traditional mechanical chucks. They reduce particulate contamination, increase the effective processing area of ​​silicon wafers, overcome the limitation of vacuum chucks in low-pressure environments, and allow for temperature control of silicon wafers. Therefore, they have become a crucial and universally applicable component in IC manufacturing processes (including ETCH, PVD, CVD, and IMP).

[0003] The primary function of an electrostatic chuck is to uniformly attract and hold wafers for high-precision machining and manufacturing. With continuous technological advancements, the operating conditions for electrostatic chucks are becoming increasingly demanding, and their functional requirements are becoming more complex. In addition to providing uniform electrostatic attraction, electrostatic chucks also need to possess good physicochemical stability, resistance to plasma bombardment, and precise temperature control (heating or cooling). This places higher demands on the ceramic and electrode materials used in electrostatic chucks.

[0004] Traditional electrostatic chucks for semiconductors encapsulate electrostatic electrodes and heating electrodes (if any) in ceramic materials. The ceramic materials used are typically alumina or aluminum nitride ceramics, and alkaline earth or rare earth sintering aids such as magnesium oxide, calcium oxide, silicon oxide, and yttrium oxide are usually added to promote sintering. However, existing electrostatic chucks use a uniform ceramic composition throughout the entire ceramic layer, without differentiating materials for the specific functions required by different ceramic layers, such as resistivity, breakdown strength, thermal conductivity, and a range of mechanical properties. A single, uniform ceramic material can no longer simultaneously meet the increasingly sophisticated performance requirements of various functions.

[0005] In addition, a large portion of the existing electrostatic chucks have ceramic layers thicker than 3mm. During the encapsulation and molding process, it is difficult to ensure the flatness and parallelism of the electrodes. Deformation of the electrode layer itself or non-parallelism to the ceramic layer will cause uneven electrostatic adsorption force or temperature control performance of the electrostatic chuck, resulting in the equipment being unable to function properly. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an aluminum nitride electrostatic chuck that utilizes a three-layer progressive hydraulic, cold isostatic pressing, and integral sintering molding process. This process results in better flatness and parallelism, thereby improving the uniformity of the electrostatic adsorption force or temperature control performance of the chuck. Furthermore, this invention also provides an aluminum nitride electrostatic chuck with different functional ceramic layers. By changing the composition and content of additives in each ceramic layer, the chemical composition, crystal phase composition, and thermal and electrical properties of each ceramic layer are different after integral sintering. This allows for the realization of different functional focuses in each ceramic layer, thus meeting the challenges of future semiconductor processes.

[0007] To achieve the above objectives, a first aspect of the present invention provides an aluminum nitride ceramic layer that exhibits both high-temperature volume resistivity and high-temperature thermal conductivity at high temperatures. The layer comprises aluminum nitride, a sintering aid, and a resistance modifier. The amount of the sintering aid is 0.1-4% of the mass of the aluminum nitride, and the amount of the resistance modifier is 0.1-2% of the mass of the aluminum nitride. Preferably, the aluminum nitride grain size is 500 nm-900 nm. Furthermore, the aluminum nitride ceramic layer is applied to an electrostatic chuck.

[0008] The second aspect of the present invention provides an electrostatic chuck, comprising a first ceramic layer, an electrostatic electrode, a second ceramic layer, a heating electrode, and a third ceramic layer. The third ceramic layer, the second ceramic layer, and the first ceramic layer are sequentially subjected to step-by-step hydraulic processing, and then joined together by cold isostatic pressing and integrally pressed and sintered to encapsulate the electrostatic electrode and the heating electrode in the ceramic layer. The preferred size of the aluminum nitride grain in the main material of the first ceramic layer is 500nm-900nm.

[0009] Preferably, the first ceramic layer is an aluminum nitride ceramic layer that has both high-temperature resistivity and high-temperature thermal conductivity at high temperatures, as described above.

[0010] Preferably, the room temperature volume resistivity of the first ceramic layer is not less than 10 Ω·cm. 16 Ω·cm, thermal conductivity at room temperature greater than 180 W / mK, and volume resistivity at 650℃ not less than 10 Ω·cm 9 Ω·cm, thermal conductivity greater than 45 W / mK; and / or, the room temperature thermal conductivity of the second ceramic layer is greater than 195 W / mK, and the room temperature volume resistivity is not less than 10 Ω·cm. 16 Ω·cm, with a volume resistivity of not less than 10 at 650℃. 8 Ω·cm, thermal conductivity higher than 65 W / mK; and / or, the room temperature thermal conductivity of the third ceramic layer is 40–100 W / mK, and the volume resistivity is not less than 10 Ω·cm. 16 Ω·cm, at 650℃, the volume resistivity is not less than 10 Ω·cm. 7 Ω·cm, thermal conductivity 10~20W / mK.

[0011] A third aspect of the present invention provides an aluminum nitride electrostatic chuck with different functional ceramic layers, including a first ceramic layer, an electrostatic electrode, a second ceramic layer, a heating electrode, and a third ceramic layer. The electrostatic electrode is located between the first ceramic layer and the second ceramic layer, and the heating electrode is located between the second ceramic layer and the third ceramic layer. The composition and content of the first ceramic layer, the second ceramic layer, and the third ceramic layer are all different, wherein the grain size of the aluminum nitride main material of the first ceramic layer is preferably 500nm-900nm.

[0012] Preferably, the room temperature volume resistivity of the first ceramic layer is not less than 10 Ω·cm. 16 Ω·cm, thermal conductivity at room temperature greater than 180 W / mK, and volume resistivity at 650℃ not less than 10 Ω·cm 9 Ω·cm, thermal conductivity greater than 45 W / mK; and / or, the room temperature thermal conductivity of the second ceramic layer is greater than 195 W / mK, and the room temperature volume resistivity is not less than 10 Ω·cm. 16 Ω·cm, with a volume resistivity of not less than 10 at 650℃. 8 Ω·cm, thermal conductivity higher than 65 W / mK; and / or, the room temperature thermal conductivity of the third ceramic layer is 40–100 W / mK, and the room temperature volume resistivity is not less than 10 Ω·cm. 16 Ω·cm, with a volume resistivity of not less than 10 at 650℃. 7 Ω·cm, thermal conductivity 10~20W / mK.

[0013] Preferably, the first ceramic layer is an aluminum nitride ceramic layer that possesses both high-temperature volume resistivity and high-temperature thermal conductivity at high temperatures, as described above; and / or, the second ceramic layer comprises aluminum nitride and sintering aid components, wherein the amount of the sintering aid is 1-5% of the mass of aluminum nitride; and / or, the third ceramic layer comprises aluminum nitride and sintering aid components, wherein the amount of the sintering aid is 1-10% of the mass of aluminum nitride.

[0014] Furthermore, the amount of sintering aid in the first ceramic layer is 0.5-3% of the mass of aluminum nitride, and the amount of resistance modifier is 0.1-0.5% of the mass of aluminum nitride; and / or, the amount of sintering aid in the second ceramic layer is 2-5% of the mass of aluminum nitride; and / or, the amount of sintering aid in the third ceramic layer is 5-10% of the mass of aluminum nitride.

[0015] Preferably, the sintering aid is one or more combinations of magnesium oxide, calcium oxide or other alkaline earth oxides, yttrium oxide, samarium oxide or other rare earth oxides, and the resistance modulator is one or more combinations of titanium, titanium oxide, titanium nitride or other nanoparticles for adjusting bulk resistance.

[0016] Preferably, the heating electrode is selected from metal pastes or wires of tungsten, molybdenum, nickel, or platinum; and / or, the electrostatic electrode is selected from metal pastes or wires of molybdenum, tungsten, or palladium.

[0017] A fourth aspect of the present invention provides a method for preparing the electrostatic chuck described above, characterized by comprising the following steps:

[0018] (1) Preparation of ceramic layer powder:

[0019] Ceramic layer powders for the first ceramic layer, the second ceramic layer, and the third ceramic layer are provided;

[0020] (2) Step-by-step hydraulic processing:

[0021] The powder of the third ceramic layer is hydraulically processed, and then heating electrodes are laid or printed on its surface.

[0022] The powder of the second ceramic layer is subjected to stepwise hydraulic processing to bond it with the third ceramic layer and the heating electrode; then an electrostatic electrode is laid or printed on its surface.

[0023] The powder of the first ceramic layer is hydraulically processed step by step to bond it with the second ceramic layer and the electrostatic electrode.

[0024] (3) Cold isostatic pressing:

[0025] The ceramic layer was removed as a whole and densified by cold isostatic pressing.

[0026] (4) Sintering and shaping:

[0027] The densified ceramic layer is transferred to a hot press furnace and sintered in one step using a hot pressing method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The aluminum nitride ceramic layer of the present invention has both high temperature resistivity and high temperature thermal conductivity at high temperature. It has high high temperature resistivity and relatively high high temperature thermal conductivity. When applied to an electrostatic chuck, it serves as the first ceramic layer, with the wafer connected to the upper part and the electrostatic electrode connected to the lower part. It can withstand the high voltage between the electrostatic electrode and the wafer without being broken down.

[0030] (2) The aluminum nitride electrostatic chuck of the present invention uses a three-layer progressive hydraulic, cold isostatic pressing and integral sintering molding process, which can make the ceramic layer have better flatness and parallelism, thereby improving the uniformity of electrostatic adsorption force or temperature control performance of the electrostatic chuck.

[0031] (3) The aluminum nitride electrostatic chuck with different functional ceramic layers in this invention has different functional ceramic layers. That is, by changing the composition and content of the additives contained in each ceramic layer, the chemical composition, crystal phase composition and thermal and electrical properties of each ceramic layer are different after integral sintering, thereby realizing the different functions of each ceramic layer.

[0032] The electrostatic chuck of the present invention and its manufacturing method are further described below with reference to the accompanying drawings. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the aluminum nitride electrostatic chuck of the present invention;

[0034] Wherein 1: aluminum nitride ceramic layer; 11: first ceramic layer; 12: second ceramic layer; 13: third ceramic layer; 14: electrostatic electrode; 15: heating electrode;

[0035] Figure 2 This is a schematic diagram of the pre-drilled aluminum nitride electrostatic chuck of the present invention;

[0036] Wherein 1: aluminum nitride ceramic layer; 21: ceramic layer with holes drilled to the electrostatic electrode; 22: ceramic layer with holes drilled to the heating electrode;

[0037] Figure 3 The XRD pattern of the aluminum nitride electrostatic chuck according to an embodiment of the present invention;

[0038] Figure 4 The image shows the SEM image of the aluminum nitride electrostatic chuck according to an embodiment of the present invention.

[0039] Figure 5 This is a SEM image of the aluminum nitride electrostatic chuck of Comparative Example 3 of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] <Aluminum nitride ceramic layer>

[0042] The first aspect of the present invention provides an aluminum nitride ceramic layer that has both high-temperature bulk resistivity and high-temperature thermal conductivity at high temperatures, comprising aluminum nitride, sintering aids and resistance modifiers.

[0043] In this embodiment, the aluminum nitride grain size in the first ceramic layer is preferably 500nm-900nm. Aluminum nitride in this range has a large specific surface area and high sintering activity, resulting in higher mass transfer efficiency during sintering of the slurry. This leads to a less porous structure and higher density in the ceramic material formed after sintering, which is beneficial for improving the thermal conductivity of the sintered ceramic slurry. In addition, the carbon content in the aluminum nitride can be controlled to be 400-700ppm and the oxygen content to be 0.5-0.8wt.%.

[0044] In this embodiment, the sintering aid and resistance modifier are uniformly distributed in aluminum nitride powder by wet ball milling with organic solvent.

[0045] In the embodiments of this application, the sintering aid can be a commonly used sintering aid, which can be one or more combinations of magnesium oxide, calcium oxide, other alkaline earth oxides, yttrium oxide, samarium oxide or other rare earth oxides.

[0046] In the embodiments of this application, the resistance modifier is one or more combinations of titanium, titanium oxide, titanium nitride, or other nanoparticles that regulate bulk resistance.

[0047] The amount of the sintering aid is 0.1-4% of the mass of aluminum nitride, and the amount of the resistance modifier is 0.1-2% of the mass of aluminum nitride; preferably, the amount of the sintering aid is 0.5-3% of the mass of aluminum nitride, and the amount of the resistance modifier is 0.1-0.5% of the mass of aluminum nitride.

[0048] The aluminum nitride ceramic layer of this invention has high volume resistivity while ensuring good thermal conductivity, especially for applications at high temperatures (200℃~650℃), providing both high high-temperature volume resistivity and relatively high high-temperature thermal conductivity. The aluminum nitride ceramic layer has a room temperature volume resistivity of not less than 10⁻⁶. 16 Ω·cm, thermal conductivity at room temperature greater than 180 W / mK, and volume resistivity at 650℃ not less than 10 Ω·cm 9 Ω·cm, thermal conductivity higher than 45W / mK.

[0049] The aluminum nitride ceramic layer of the present invention, which has both high-temperature volume resistivity and high-temperature thermal conductivity, is applied to an electrostatic chuck as the first ceramic layer, with the wafer connected above and the electrostatic electrode connected below. It can withstand the high voltage between the electrostatic electrode and the wafer without being broken down.

[0050] <Aluminum Nitride Electrostatic Chuck>

[0051] A second aspect of the present invention provides an aluminum nitride electrostatic chuck 1, such as... Figure 1As shown, it includes a first ceramic layer 11, an electrostatic electrode 14, a second ceramic layer 12, a heating electrode 15, and a third ceramic layer 13. The electrostatic electrode 14 is located between the first ceramic layer 11 and the second ceramic layer 12, and the heating electrode 15 is located between the second ceramic layer 12 and the third ceramic layer 13. The third ceramic layer 13, the second ceramic layer 12, and the first ceramic layer 11 are sequentially subjected to step-by-step hydraulic processing, and then joined together by cold isostatic pressing and integrally pressed and sintered to encapsulate the electrostatic electrode 14 and the heating electrode 15 in the ceramic layers. The composition and content of the third ceramic layer 13, the second ceramic layer 12, and the first ceramic layer 11 may be the same or different.

[0052] The term "gradual hydraulic press" refers to the use of a hydraulic press to gradually increase pressure, with each press increasing in pressure until it covers the previous press.

[0053] The specific process of the above-mentioned aluminum nitride electrostatic chuck 1 is as follows: (1) the powder of the third ceramic layer 13 is hydraulically treated, and then the heating electrode 15 is laid or printed on its surface; (2) the powder of the second ceramic layer 12 is hydraulically treated step by step to combine it with the third ceramic layer 13 and the heating electrode 15; then the electrostatic electrode 14 is laid or printed on its surface; (3) the powder of the first ceramic layer 11 is hydraulically treated step by step to combine it with the second ceramic layer 12 and the electrostatic electrode 14; (4) the above-mentioned ceramic layer is taken out as a whole and densified by cold isostatic pressing; (5) the ceramic layer is transferred to a hot press furnace and sintered in one step by hot pressing.

[0054] The first ceramic layer comprises aluminum nitride, sintering aids, and resistance modifiers.

[0055] The amount of the sintering aid is 0.1-4% of the mass of aluminum nitride, and the amount of the resistance modifier is 0.1-2% of the mass of aluminum nitride; preferably, the amount of the sintering aid is 0.5-3% of the mass of aluminum nitride, and the amount of the resistance modifier is 0.1-0.5% of the mass of aluminum nitride.

[0056] In this embodiment, the main material of the first ceramic layer is aluminum nitride, and the preferred grain size of aluminum nitride is 500nm-900nm. In addition, the carbon content in aluminum nitride can be controlled to be 400-700ppm and the oxygen content to be 0.5-0.8wt.%.

[0057] In this application, the sintering aid and resistance modifier in the first ceramic layer have a grain size of 50nm-300nm, preferably 50nm-100nm.

[0058] The second ceramic layer includes aluminum nitride and sintering aids.

[0059] The amount of the sintering aid is 1-5% of the mass of aluminum nitride; preferably, the amount of the sintering aid in the second ceramic layer is 2-5% of the mass of aluminum nitride.

[0060] In this embodiment, the main material of the second ceramic layer is aluminum nitride, and the preferred grain size of aluminum nitride is 500nm-900nm. In addition, the carbon content in aluminum nitride can be controlled to be 400-700ppm and the oxygen content to be 0.5-0.8wt.%.

[0061] In this application, the sintering aid in the second ceramic layer has a size of 50nm-300nm, preferably 50nm-100nm.

[0062] The third ceramic layer includes aluminum nitride and sintering aids.

[0063] The amount of the sintering aid is 1-10% of the mass of aluminum nitride; preferably, the amount of the sintering aid in the third ceramic layer is 5-10% of the mass of aluminum nitride.

[0064] In this embodiment, the main material of the third ceramic layer is aluminum nitride, and the preferred grain size of aluminum nitride is 500nm-900nm. In addition, the carbon content in aluminum nitride can be controlled to be 400-700ppm and the oxygen content to be 0.5-0.8wt.%.

[0065] In this application, the sintering aid in the third ceramic layer has a size of 50nm-300nm, preferably 50nm-100nm.

[0066] The heating electrode is selected from tungsten, molybdenum, nickel, and platinum metal pastes or metal wires.

[0067] The electrostatic electrode is selected from molybdenum, tungsten, palladium metal paste or metal wire.

[0068] The aluminum nitride electrostatic chuck of the present invention uses a three-layer progressive hydraulic treatment, cold isostatic pressing and integral sintering molding process, which can make the ceramic layer thickness more than 3mm have good flatness and parallelism, thereby improving the uniformity of electrostatic adsorption force or temperature control performance of the electrostatic chuck.

[0069] like Figure 2 As shown, the aluminum nitride electrostatic chuck of the present invention further includes drilling 21 holes in the densified ceramic layer to the electrostatic electrode 14, providing a channel for filling electrode slurry or connecting wires to the external circuit, and drilling 22 holes to the heating electrode 15, providing a channel for filling electrode slurry or connecting wires to the external circuit. Subsequently, the holes are enlarged by machining at the pre-drilled positions to connect with the air and electrical circuits of the base.

[0070] <Aluminum nitride electrostatic chuck with different functional ceramic layers>

[0071] A third aspect of the present invention provides an aluminum nitride electrostatic chuck with different functional ceramic layers, such as... Figure 1 As shown, an aluminum nitride electrostatic chuck 1 with different functional ceramic layers includes a first ceramic layer 11, an electrostatic electrode 14, a second ceramic layer 12, a heating electrode 15, and a third ceramic layer 13. The electrostatic electrode 14 is located between the first ceramic layer 11 and the second ceramic layer 12, and the heating electrode 15 is located between the second ceramic layer 12 and the third ceramic layer 13. The composition and content of the first ceramic layer 11, the second ceramic layer 12, and the third ceramic layer 13 are all different.

[0072] The heating electrode is selected from tungsten, molybdenum, nickel, and platinum metal pastes or metal wires.

[0073] The electrostatic electrode is selected from metal pastes or wires of molybdenum, tungsten, palladium, and titanium.

[0074] The first ceramic layer includes aluminum nitride, sintering aids, and resistance modifiers.

[0075] The sintering aid is one or more combinations of magnesium oxide, calcium oxide, other alkaline earth oxides, yttrium oxide, samarium oxide or other rare earth oxides, and the resistance modifier is one or more combinations of titanium, titanium oxide or titanium nitride or other nanoparticles that regulate bulk resistance.

[0076] The sintering aid is used at 0.1-4% of the mass of aluminum nitride, and the resistance modifier is used at 0.1-2% of the mass of aluminum nitride; preferably, the sintering aid is used at 0.5-3% of the mass of aluminum nitride, and the resistance modifier is used at 0.1-0.5% of the mass of aluminum nitride. If the content of the sintering aid and resistance modifier is too low, the corresponding thermal conductivity and volume resistivity will not be achieved; if the content is too high, it will disrupt the continuity of aluminum nitride itself.

[0077] In this embodiment, the main material of the first ceramic layer is aluminum nitride, and the preferred grain size of aluminum nitride is 500nm-900nm. In addition, the carbon content in aluminum nitride can be controlled to be 400-700ppm and the oxygen content to be 0.5-0.8wt.%.

[0078] In this application, the sintering aid and resistance modulator in the first ceramic layer have a grain size of 50nm-300nm, preferably 50nm-100nm.

[0079] The first ceramic layer focuses on electrical properties, providing high volume resistivity while ensuring good thermal conductivity; especially for applications at high temperatures (200℃~650℃), it provides high high-temperature volume resistivity and relatively high high-temperature thermal conductivity. The first ceramic layer is used in an electrostatic chuck, connecting the wafer to the top and the electrostatic electrode to the bottom, and can withstand the high voltage between the electrostatic electrode and the wafer without being broken down.

[0080] The second ceramic layer includes aluminum nitride and sintering aids.

[0081] The sintering aid is one or a combination of magnesium oxide, calcium oxide, other alkaline earth oxides, yttrium oxide, samarium oxide, or other rare earth oxides.

[0082] The amount of sintering aid is 1-5% of the mass of aluminum nitride; preferably, the amount of sintering aid in the second ceramic layer is 2-5% of the mass of aluminum nitride. If the content of sintering aid is too small, the corresponding thermal conductivity will not be achieved; if the content is too large, it will destroy the continuity of aluminum nitride itself.

[0083] In this embodiment, the main material of the second ceramic layer is aluminum nitride, and the preferred grain size of aluminum nitride is 500nm-900nm. In addition, the carbon content in aluminum nitride can be controlled to be 400-700ppm and the oxygen content to be 0.5-0.8wt.%.

[0084] In this application, the sintering aid in the second ceramic layer has a size of 50nm-300nm, preferably 50nm-100nm.

[0085] The second ceramic layer connects the first ceramic layer and the electrostatic electrode to the top, and the heating electrode to the bottom. It is required to rapidly and efficiently conduct the heat generated by the heating electrode to the upper first ceramic layer to heat the wafer. Therefore, the second ceramic layer focuses on thermal performance, providing high thermal conductivity while ensuring good bulk resistivity. Especially for applications at high temperatures (200℃~650℃), it provides high high-temperature thermal conductivity and relatively high high-temperature bulk resistivity.

[0086] The third ceramic layer includes aluminum nitride and sintering aids.

[0087] The sintering aid is one or a combination of magnesium oxide, calcium oxide, other alkaline earth oxides, yttrium oxide, samarium oxide, or other rare earth oxides.

[0088] The amount of sintering aid is 1-10% of the mass of aluminum nitride; preferably, the amount of sintering aid in the third ceramic layer is 5-10% of the mass of aluminum nitride. If the content of sintering aid is too small, the corresponding effect will not be achieved; if the content is too large, it will destroy the continuity of aluminum nitride itself.

[0089] In this embodiment, the main material of the third ceramic layer is aluminum nitride, and the preferred grain size of aluminum nitride is 500nm-900nm. In addition, the carbon content in aluminum nitride can be controlled to be 400-700ppm and the oxygen content to be 0.5-0.8wt.%.

[0090] In this application, the sintering aid in the third ceramic layer has a size of 50nm-300nm, preferably 50nm-100nm.

[0091] The heating electrode is attached to the third ceramic layer, which is the bottom layer of the ceramic disk. It provides base support for the ceramic layer and connects to the metal or ceramic base. The heat generated by the heating electrode must be conducted upwards to the second and first ceramic layers for heating the wafer, reducing heat loss due to downward conduction to the substrate, handle, or external environment. Therefore, the third ceramic layer provides low thermal conductivity, preventing heat conduction and dissipation within the third ceramic layer, guiding the heat generated by the heating electrode upwards, while maintaining good volume resistivity.

[0092] The present invention relates to an aluminum nitride electrostatic chuck with different functional ceramic layers. By changing the composition and content of additives contained in each ceramic layer, the chemical composition, crystal phase composition, and thermal and electrical properties of each ceramic layer are different after integral sintering. This allows each ceramic layer to achieve different functions, solving the problem that the same uniform ceramic material cannot simultaneously meet the ever-increasing performance requirements of electrostatic chucks.

[0093] The aluminum nitride electrostatic chuck with different functional ceramic layers described in this invention uses the above-mentioned three-layer step-by-step hydraulic processing, cold isostatic pressing and integral sintering forming process.

[0094] <Preparation method of aluminum nitride electrostatic chuck with different functional ceramic layers>

[0095] A fourth aspect of this invention provides a method for preparing an aluminum nitride electrostatic chuck with different functional ceramic layers, comprising the following steps:

[0096] (1) Preparation of ceramic layer powder:

[0097] Ceramic layer powders for the first ceramic layer, the second ceramic layer, and the third ceramic layer are provided;

[0098] (2) Step-by-step hydraulic processing:

[0099] The powder of the third ceramic layer is hydraulically processed, and then heating electrodes are laid or printed on its surface.

[0100] The powder of the second ceramic layer is subjected to stepwise hydraulic processing to bond it with the third ceramic layer and the heating electrode; then an electrostatic electrode is laid or printed on its surface.

[0101] The powder of the first ceramic layer is subjected to stepwise hydraulic processing to bond it with the second ceramic layer and the electrostatic electrode.

[0102] (3) Cold isostatic pressing:

[0103] The ceramic layer was removed as a whole and densified by cold isostatic pressing.

[0104] (4) Integrated sintering:

[0105] The densified ceramic layer is transferred to a hot press furnace and sintered in one step using a hot pressing method.

[0106] The specific steps of the above-mentioned step-by-step hydraulic processing are as follows:

[0107] The powder of the third ceramic layer is filled into a hydraulic mold. First, the powder is compacted by vibration, and then pressure is repeatedly applied at 5-10 MPa and held for 5-10 minutes. Then, heating electrodes are laid or printed on its surface.

[0108] The powder of the second ceramic layer is filled into a hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by 10-15 MPa and held for 10-15 minutes to bond it with the third ceramic layer and the heating electrode. Then, an electrostatic electrode is laid or printed on its surface.

[0109] The powder of the first ceramic layer is filled into a hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressurized by a pressure of 15-25 MPa and held for 15-20 minutes to bond it with the second ceramic layer and the electrostatic electrode.

[0110] The specific steps of the above-mentioned cold isostatic pressing treatment are as follows: the ceramic layer is removed as a whole, and densification is achieved by applying a pressure of 125-160 MPa and holding the pressure for 10-20 minutes through cold isostatic pressing.

[0111] The above-mentioned integral sintering molding includes the following steps:

[0112] (1) Evacuate the vacuum and heat it to 1000-1200℃ at a heating rate of 5-10℃ / min, and keep it at that temperature for 10-60 minutes;

[0113] (2) Fill with nitrogen to a slightly positive pressure and heat to 1400-1600℃ at a heating rate of 5-10℃ / min, and keep warm for 10-60 minutes;

[0114] (3) Evacuate the vacuum and introduce argon gas to a slightly positive pressure, and heat to 1700-1850℃ at a heating rate of 5-10℃ / min, and hold for 60-120 minutes;

[0115] (4) When the temperature reaches 1000-1200℃, start pressurizing. The maximum pressure is 5-30MPa. Adjust the pressurization rate so that the maximum pressure and the maximum temperature are reached at the same time.

[0116] (5) After that, it is cooled with the furnace.

[0117] The above and other advantages of the present invention can be better understood through the following embodiments, but the following embodiments are not intended to limit the scope of the present invention.

[0118] Example

[0119] The following embodiments illustrate the present invention, but the present invention is not limited to the following embodiments.

[0120] <Testing Methods>

[0121] Thermal conductivity: measured using a high-temperature thermal conductivity meter in accordance with GB / T 39862-2021.

[0122] Volume resistivity: Measured using a high-temperature volume resistivity measuring instrument in accordance with GB / T 5594.5-1985.

[0123] Example 1

[0124] 1. Preparation of ceramic layer powder:

[0125] The first ceramic layer powder formula is as follows: 100 parts aluminum nitride (grain size of 600nm, carbon content of 400ppm, oxygen content of 0.7wt.%), 0.5 parts magnesium oxide, 0.5 parts yttrium oxide, and 0.2 parts titanium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0126] The second ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 600nm, carbon content of 400ppm, oxygen content of 0.7wt.%) and 2 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0127] The third ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 600nm, carbon content of 400ppm, oxygen content of 0.7wt.%) and 6 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0128] 2. Step-by-step hydraulic processing:

[0129] The powder of the third ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 10MPa and held for 5 minutes to compact the powder and remove the gas in the powder. After it has a certain strength, the heating electrode molybdenum wire is laid on its upper surface.

[0130] The powder of the second ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, the pressure of 15MPa is repeatedly applied and held for 15 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the third ceramic layer and the heating electrode. After it has a certain strength, the electrostatic electrode molybdenum wire is laid on its upper surface.

[0131] The powder of the first ceramic layer is filled into a hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 25MPa and held for 20 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the second ceramic layer and the electrostatic electrode and have a certain strength.

[0132] 3. Cold isostatic pressing process:

[0133] The ceramic layer was removed as a whole and densified by applying a pressure of 125 MPa and holding it for 10 minutes under cold isostatic pressing.

[0134] 4. Sintering process:

[0135] The densified ceramic layer was transferred to a hot press furnace, evacuated, and heated to 1000°C at a rate of 10°C / min, and held for 60 minutes. Nitrogen gas was then introduced to a slightly positive pressure, and the temperature was increased to 1400°C at a rate of 5°C / min, and held for 60 minutes. A vacuum was then evacuated, and argon gas was introduced to a slightly positive pressure, and the temperature was increased to 1700°C at a rate of 5°C / min, and held for 120 minutes. When the temperature reached 1000°C, pressurization was started, with a maximum pressure of 15 MPa. The pressurization rate was adjusted so that the maximum pressure and the maximum temperature were reached simultaneously. Afterward, the furnace was cooled.

[0136] Crystal phase composition was determined by XRD, such as Figure 3 As shown, the first ceramic layer phase is AlN+Y4Al2O9+MgAl2O4; the second ceramic layer phase is AlN+Y4Al2O9+YAlO3; and the third ceramic layer phase is AlN+Y5Al3O4. 12 .

[0137] The distribution of ceramic layer grains and the second phase was determined using a scanning electron microscope in backscatter mode, such as... Figure 4 As shown, the first ceramic layer (Fig. a-1) has ceramic grains <3μm, the second phase is well dispersed, and the sintering is dense; the second ceramic layer (Fig. a-2) has ceramic grains <3μm, the second phase is well dispersed, and the sintering is dense; the third ceramic layer (Fig. a-3) has ceramic grains <3μm, the second phase is well dispersed, and the sintering is dense.

[0138] The thermal conductivity and volume resistivity data of the aluminum nitride electrostatic chuck prepared in Example 1 are shown in Table 1 below.

[0139] Table 1

[0140]

[0141] The flatness of the electrodes of the aluminum nitride electrostatic chuck was measured by 3D laser confocal microscopy, and the flatness of the electrostatic electrode and the heating electrode were 54 μm and 73 μm, respectively.

[0142] Example 2

[0143] 1. Preparation of ceramic layer powder:

[0144] The first ceramic layer powder formula is as follows: 100 parts aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%), 0.6 parts magnesium oxide, 0.6 parts yttrium oxide, and 0.1 parts titanium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0145] The second ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 3 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0146] The third ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 8 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0147] 2. Step-by-step hydraulic processing:

[0148] The powder of the third ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 10MPa and held for 5 minutes to compact the powder and remove the gas in the powder. After it has a certain strength, the heating electrode molybdenum wire is laid on its upper surface.

[0149] The powder of the second ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, the pressure of 15MPa is repeatedly applied and held for 15 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the third ceramic layer and the heating electrode. After it has a certain strength, the electrostatic electrode molybdenum wire is laid on its upper surface.

[0150] The powder of the first ceramic layer is filled into a hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 25MPa and held for 20 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the second ceramic layer and the electrostatic electrode and have a certain strength.

[0151] 3. Cold isostatic pressing process:

[0152] The ceramic layer was removed as a whole and densified by applying a pressure of 125 MPa and holding it for 10 minutes under cold isostatic pressing.

[0153] 4. Sintering process:

[0154] The densified ceramic layer was transferred to a hot press furnace, evacuated, and heated to 1000°C at a rate of 10°C / min, and held for 60 minutes. Nitrogen gas was then introduced to a slightly positive pressure, and the temperature was increased to 1400°C at a rate of 5°C / min, and held for 60 minutes. A vacuum was then evacuated, and argon gas was introduced to a slightly positive pressure, and the temperature was increased to 1700°C at a rate of 5°C / min, and held for 120 minutes. When the temperature reached 1000°C, pressurization was started, with a maximum pressure of 15 MPa. The pressurization rate was adjusted so that the maximum pressure and the maximum temperature were reached simultaneously. Afterward, the furnace was cooled.

[0155] The crystal phase composition was determined by XRD. The phases of each layer remained unchanged. The first ceramic layer phase was AlN+Y4Al2O9+MgAl2O4; the second ceramic layer phase was AlN+Y4Al2O9+YAlO3; and the third ceramic layer phase was AlN+Y5Al3O4. 12 .

[0156] The distribution of ceramic grains and the second phase was determined by scanning electron microscopy in backscatter mode. The three ceramic layers showed that the ceramic grains were <3μm, the second phase was well dispersed, and the sintering was dense.

[0157] The thermal conductivity and volume resistivity data of the aluminum nitride electrostatic chuck prepared in Example 2 are shown in Table 2 below.

[0158] Table 2

[0159]

[0160] The flatness of the electrodes of the aluminum nitride electrostatic chuck was measured by 3D laser confocal microscopy, and the flatness of the electrostatic electrode and the heating electrode were 55 μm and 73 μm, respectively.

[0161] Example 3

[0162] 1. Preparation of ceramic layer powder:

[0163] The first ceramic layer powder formula is as follows: 100 parts aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%), 1.2 parts magnesium oxide, 1.4 parts yttrium oxide, and 0.4 parts titanium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0164] The second ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 5 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0165] The third ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 800nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 7 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0166] 2. Step-by-step hydraulic processing:

[0167] The powder of the third ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 10MPa and held for 5 minutes to compact the powder and remove the gas in the powder. After it has a certain strength, the heating electrode molybdenum wire is laid on its upper surface.

[0168] The powder of the second ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, the pressure of 15MPa is repeatedly applied and held for 15 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the third ceramic layer and the heating electrode. After it has a certain strength, the electrostatic electrode molybdenum wire is laid on its upper surface.

[0169] The powder of the first ceramic layer is filled into a hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 25MPa and held for 20 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the second ceramic layer and the electrostatic electrode and have a certain strength.

[0170] 3. Cold isostatic pressing process:

[0171] The ceramic layer was removed as a whole and densified by applying a pressure of 125 MPa and holding it for 10 minutes under cold isostatic pressing.

[0172] 4. Sintering process:

[0173] The densified ceramic layer was transferred to a hot press furnace, evacuated, and heated to 1000°C at a rate of 10°C / min, and held for 60 minutes. Nitrogen gas was then introduced to a slightly positive pressure, and the temperature was increased to 1400°C at a rate of 5°C / min, and held for 60 minutes. A vacuum was then evacuated, and argon gas was introduced to a slightly positive pressure, and the temperature was increased to 1700°C at a rate of 5°C / min, and held for 120 minutes. When the temperature reached 1000°C, pressurization was started, with a maximum pressure of 15 MPa. The pressurization rate was adjusted so that the maximum pressure and the maximum temperature were reached simultaneously. Afterward, the furnace was cooled.

[0174] XRD analysis revealed no significant changes in the phase composition of each ceramic layer. The first ceramic layer consisted of AlN+Y4Al2O9+MgAl2O4; the second ceramic layer consisted of AlN+Y4Al2O9+YAlO3; and the third ceramic layer consisted of AlN+Y5Al3O4. 12 .

[0175] The distribution of ceramic grains and the second phase was determined by scanning electron microscopy in backscatter mode. The three ceramic layers showed that the ceramic grains were <3μm, the second phase was well dispersed, and the sintering was dense.

[0176] The thermal conductivity and volume resistivity data of the aluminum nitride electrostatic chuck prepared in Example 3 are shown in Table 3 below.

[0177] Table 3

[0178]

[0179] The flatness of the electrodes of the aluminum nitride electrostatic chuck was measured by 3D laser confocal microscopy, and the flatness of the electrostatic electrode and the heating electrode were 62 μm and 85 μm, respectively.

[0180] Example 4

[0181] 1. Preparation of ceramic layer powder:

[0182] The first ceramic layer powder formula is as follows: 100 parts aluminum nitride (grain size of 800nm, carbon content of 500ppm, oxygen content of 0.6wt.%), 0.5 parts magnesium oxide, 0.5 parts yttrium oxide, and 0.2 parts titanium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0183] The second ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 2 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0184] The third ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 6 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0185] 2. Step-by-step hydraulic processing:

[0186] The powder of the third ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 5MPa and held for 5 minutes to compact the powder and remove the gas in the powder. After it has a certain strength, the heating electrode molybdenum wire is laid on its upper surface.

[0187] The powder of the second ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, the pressure of 10MPa is repeatedly applied and held for 10 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the third ceramic layer and the heating electrode. After it has a certain strength, the electrostatic electrode molybdenum wire is laid on its upper surface.

[0188] The powder of the first ceramic layer is filled into a hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 20MPa and held for 15 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the second ceramic layer and the electrostatic electrode and have a certain strength.

[0189] 3. Cold isostatic pressing process:

[0190] The ceramic layer was removed as a whole and densified by applying a pressure of 150 MPa and holding it for 15 minutes under cold isostatic pressing.

[0191] 4. Sintering process:

[0192] The densified ceramic layer was transferred to a hot press furnace, evacuated, and heated to 1000°C at a rate of 10°C / min, and held for 60 minutes. Nitrogen gas was then introduced to a slightly positive pressure, and the temperature was increased to 1400°C at a rate of 5°C / min, and held for 60 minutes. A vacuum was then evacuated, and argon gas was introduced to a slightly positive pressure, and the temperature was increased to 1700°C at a rate of 5°C / min, and held for 120 minutes. When the temperature reached 1000°C, pressurization was started, with a maximum pressure of 15 MPa. The pressurization rate was adjusted so that the maximum pressure and the maximum temperature were reached simultaneously. Afterward, the furnace was cooled.

[0193] The crystal phase composition was determined by XRD. The phases of each layer remained unchanged. The first ceramic layer phase was AlN+Y4Al2O9+MgAl2O4; the second ceramic layer phase was AlN+Y4Al2O9+YAlO3; and the third ceramic layer phase was AlN+Y5Al3O4. 12 .

[0194] The distribution of ceramic grains and the second phase was determined by scanning electron microscopy in backscatter mode. The three ceramic layers showed that the ceramic grains were <3μm, the second phase was well dispersed, and the sintering was dense.

[0195] The thermal conductivity and volume resistivity data of the aluminum nitride electrostatic chuck prepared in Example 4 are shown in Table 4 below.

[0196] Table 4

[0197]

[0198] The flatness of the electrodes of the aluminum nitride electrostatic chuck was measured by 3D laser confocal microscopy, and the flatness of the electrostatic electrode and the heating electrode were 65 μm and 75 μm, respectively.

[0199] Example 5

[0200] 1. Preparation of ceramic layer powder:

[0201] The first ceramic layer powder formula is as follows: 100 parts aluminum nitride (grain size of 900nm, carbon content of 500ppm, oxygen content of 0.6wt.%), 0.5 parts magnesium oxide, 0.5 parts yttrium oxide, and 0.2 parts titanium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0202] The second ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 800nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 2 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0203] The third ceramic layer powder formula is as follows: 100 parts of aluminum nitride (grain size of 900nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 6 parts of yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0204] 2. Step-by-step hydraulic processing:

[0205] The powder of the third ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 10MPa and held for 5 minutes to compact the powder and remove the gas in the powder. After it has a certain strength, the heating electrode molybdenum wire is laid on its upper surface.

[0206] The powder of the second ceramic layer is filled into the hydraulic mold, and the powder is compacted by vibration. Then, the pressure of 15MPa is repeatedly applied and held for 15 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the third ceramic layer and the heating electrode. After it has a certain strength, the electrostatic electrode molybdenum wire is laid on its upper surface.

[0207] The powder of the first ceramic layer is filled into a hydraulic mold, and the powder is compacted by vibration. Then, it is repeatedly pressed by a pressure of 25MPa and held for 20 minutes to compact the powder and remove the gas in the powder, so that it can be combined with the second ceramic layer and the electrostatic electrode and have a certain strength.

[0208] 3. Cold isostatic pressing process:

[0209] The ceramic layer was removed as a whole and densified by applying a pressure of 125 MPa and holding it for 10 minutes under cold isostatic pressing.

[0210] 4. Sintering process:

[0211] The ceramic layer was transferred to a hot pressurized furnace, evacuated, and heated to 1000°C at a rate of 10°C / min, and held for 60 minutes. Nitrogen gas was then introduced to a slightly positive pressure, and the temperature was increased to 1500°C at a rate of 5°C / min, and held for 60 minutes. A vacuum was then created, and argon gas was introduced to a slightly positive pressure, and the temperature was increased to 1750°C at a rate of 5°C / min, and held for 120 minutes. When the temperature reached 1000°C, pressurization was started, with a maximum pressure of 20 MPa. The pressurization rate was adjusted so that the maximum pressure and the maximum temperature were reached simultaneously. Afterward, the furnace was cooled.

[0212] XRD analysis revealed no significant changes in the phase composition of each ceramic layer. The first ceramic layer consisted of AlN+Y4Al2O9+MgAl2O4; the second ceramic layer consisted of AlN+Y4Al2O9+YAlO3; and the third ceramic layer consisted of AlN+Y5Al3O4. 12 .

[0213] The distribution of ceramic grains and the second phase was determined by scanning electron microscopy in backscatter mode. The three ceramic layers showed that the ceramic grains were <3μm, the second phase was well dispersed, and the sintering was dense.

[0214] The thermal conductivity and volume resistivity data of the aluminum nitride electrostatic chuck prepared in Example 5 are shown in Table 5 below.

[0215] Table 5

[0216]

[0217] The flatness of the electrodes of the aluminum nitride electrostatic chuck was measured by 3D laser confocal microscopy, and the flatness of the electrostatic electrode and the heating electrode were 65 μm and 82 μm, respectively.

[0218] Comparative Example 1

[0219] The difference between this comparative example and Example 1 is that the aluminum nitride in the first ceramic layer powder, the second ceramic layer powder and the third ceramic layer powder are different. The aluminum nitride in the first ceramic layer powder, the second ceramic layer powder and the third ceramic layer powder has a grain size of 1200nm, a carbon content of 800ppm and an oxygen content of 0.9wt.%, while other conditions are the same.

[0220] XRD analysis revealed no significant changes in the phase composition of each ceramic layer. The first ceramic layer consisted of AlN+Y4Al2O9+MgAl2O4; the second ceramic layer consisted of AlN+Y4Al2O9+YAlO3; and the third ceramic layer consisted of AlN+Y5Al3O4. 12 .

[0221] The distribution of ceramic grains and the second phase was determined by scanning electron microscopy in backscatter mode. The three ceramic layers showed that the ceramic grains were >5μm, the second phase was well dispersed, and the sintering was dense.

[0222] The thermal conductivity and volume resistivity data of the aluminum nitride electrostatic chuck prepared in Comparative Example 1 are shown in Table 6 below.

[0223] Table 6

[0224]

[0225] The flatness of the electrodes of the aluminum nitride electrostatic chuck was measured by 3D laser confocal microscopy, and the flatness of the electrostatic electrode and the heating electrode were 55 μm and 70 μm, respectively.

[0226] Comparative Example 2

[0227] 1. Preparation of ceramic layer powder:

[0228] Ceramic layer powder formulation: 100 parts aluminum nitride (grain size 700nm, carbon content 500ppm, oxygen content 0.6wt.%) and 2 parts yttrium oxide are wet ball-milled in alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0229] 2. One-piece hot pressing molding

[0230] The ceramic layer powder is filled into a hot press mold, and the powder is compacted by vibration. A heating electrode molybdenum wire is then laid on its upper surface.

[0231] The ceramic layer powder is filled into a hot press mold, and the powder is compacted by vibration. Electrostatic electrode molybdenum wire is then laid on its upper surface.

[0232] The ceramic layer powder is filled into a hot press mold, and the powder is compacted by vibration.

[0233] 3. Sintering

[0234] The ceramic layer was transferred to a hot pressurized furnace, evacuated, and heated to 1000°C at a rate of 10°C / min, and held for 60 minutes. Nitrogen gas was then introduced to a slightly positive pressure, and the temperature was increased to 1400°C at a rate of 5°C / min, and held for 60 minutes. A vacuum was then created, and argon gas was introduced to a slightly positive pressure, and the temperature was increased to 1700°C at a rate of 5°C / min, and held for 120 minutes. When the temperature reached 1000°C, pressurization was started, with a maximum pressure of 15 MPa. The pressurization rate was adjusted so that the maximum pressure and the maximum temperature were reached simultaneously. Afterward, the furnace was cooled.

[0235] The crystal phase composition was determined by XRD, and the composition of all three phases was AlN+Y4Al2O9+YAlO3.

[0236] The distribution of ceramic layer grains and second phase was evaluated by scanning electron microscopy backscatter mode measurement. The three ceramic layers showed that the ceramic grains were <3μm, the second phase was well dispersed, and the sintering was dense.

[0237] The thermal conductivity and volume resistivity data of the aluminum nitride electrostatic chuck prepared in Comparative Example 2 are shown in Table 7 below.

[0238] Table 7

[0239]

[0240] The three ceramic layers have the same composition. After being fired together, the three ceramic layers have the same phase, thermal and electrical properties. It is impossible to focus on any one aspect, which will make the heating plate relatively easy to be broken down by high voltage and relatively low heat utilization efficiency.

[0241] The flatness of the electrodes of the aluminum nitride electrostatic chuck was measured by a 3D laser confocal microscope. The flatness of the electrostatic electrode and the heating electrode mesh were 430 μm and 670 μm, respectively. Due to the lack of pre-pressing, the electrode mesh deformed with the flow of ceramic powder during the hot pressing sintering process, resulting in a significant decrease in the overall flatness of the electrodes and obvious undulations.

[0242] Comparative Example 3

[0243] 1. Preparation of ceramic layer powder:

[0244] The powder formulations for the first, second, and third ceramic layers are as follows: 100 parts aluminum nitride (grain size of 700nm, carbon content of 500ppm, oxygen content of 0.6wt.%) and 2 parts yttrium oxide are wet-milled in an alcohol medium for 24 hours, dried at 80℃, ground and crushed, and then passed through a 200-mesh sieve for later use.

[0245] 2. Pre-pressing and firing:

[0246] The powder for the first ceramic layer is filled into a hot press mold, and the powder is compacted by vibration. Sintering is completed using the following sintering process curve:

[0247] In the autoclave, a vacuum is drawn, and the temperature is increased to 1000℃ at a rate of 10℃ / min, and held for 60 minutes. Nitrogen gas is then introduced to a slightly positive pressure, and the temperature is increased to 1400℃ at a rate of 5℃ / min, and held for 60 minutes. A vacuum is then drawn, and argon gas is introduced to a slightly positive pressure, and the temperature is increased to 1700℃ at a rate of 5℃ / min, and held for 120 minutes. When the temperature reaches 1000℃, pressurization begins, with a maximum pressure of 15MPa. The pressurization rate is adjusted so that the maximum pressure and the maximum temperature are reached simultaneously.

[0248] The first ceramic layer, once fired, is removed, machined to a flat surface, and set aside for later use.

[0249] Repeat the above process to obtain two more ceramic layers, the second ceramic layer and the third ceramic layer, respectively.

[0250] 3. Adhesive assembly:

[0251] (1) Preparation of slurry for the first, second and third ceramic layers: 100 parts aluminum nitride and 2 parts yttrium oxide were wet ball-milled in 50 parts alcohol medium for 24 hours, then 7 parts of binder polyvinyl butyral and 3 parts of plasticizer dibutyl phthalate were added, and the mixture was ball-milled for another 24 hours before being taken out for use.

[0252] (2) Apply the second ceramic layer slurry between the pre-fired third and second ceramic layers, and embed the heating electrode in the slurry;

[0253] (3) Apply a second ceramic layer slurry between the pre-fired second and first ceramic layers, and embed an electrostatic electrode in the slurry;

[0254] (4) The three ceramic layers are bonded together by debinding and pressurizing sintering at a temperature of 1600℃, a holding time of 30min, and a pressure of 20MPa.

[0255] The crystal phase composition was determined by XRD, and all three phases were AlN+Y4Al2O9+YAlO3;

[0256] The distribution of ceramic layer grains and the second phase was determined using a scanning electron microscope in backscatter mode, such as... Figure 5 As shown, due to the two sintering processes, grain growth is common in the first (Figure b-1), second (Figure b-2), and third (Figure b-3) ceramic layers, with grain size > 10 μm.

[0257] The thermal conductivity and bulk resistivity data of the aluminum nitride electrostatic chuck prepared in Comparative Example 3 are shown in Table 8 below:

[0258] Table 8

[0259]

[0260] The overall decline in the performance of the ceramic layer is mainly due to the growth of the ceramic grains caused by secondary sintering, resulting in uneven grain size.

[0261] The three ceramic layers have the same composition. After being fired together, the three ceramic layers have the same phase, thermal and electrical properties. It is impossible to focus on any one aspect, which will make the heating plate relatively easy to be broken down by high voltage and relatively low heat utilization efficiency.

[0262] The flatness of the electrodes was measured by 3D laser confocal microscopy, and the flatness of the electrostatic electrode and the heating electrode mesh were 92 μm and 173 μm, respectively.

[0263] The aluminum nitride electrostatic chuck of the present invention has different functional ceramic layers, wherein the room temperature volume resistivity of the first ceramic layer is not less than 10. 16 Its thermal conductivity at room temperature is greater than 180 W / mK, and its volume resistivity does not decrease significantly when the temperature rises from room temperature to 150℃, remaining within 10 Ω·cm. 16 Ω·cm; with continued heating, its resistivity gradually and slowly decreases with increasing temperature (the rate of decrease is much lower than that of ordinary aluminum nitride structural ceramics), and at 200℃, its bulk resistivity is not less than 10 Ω·cm; 15 Its volume resistivity is not less than 10 Ω·cm at 300℃. 14 Its volume resistivity is not less than 10 Ω·cm at 400℃. 13 Its volume resistivity is not less than 10 Ω·cm at 500℃. 12 Its volume resistivity is not less than 10 Ω·cm at 600℃. 10 Its volume resistivity is not less than 10 Ω·cm at 650℃. 9 Its thermal conductivity is greater than 45 W / mK at 650℃, with Ω·cm.

[0264] The second ceramic layer has a thermal conductivity greater than 195 W / mK at room temperature and a volume resistivity of not less than 10 Ω·m at room temperature. 16 Its volume resistivity is Ω·cm, which slowly decreases with increasing temperature, and is not less than 10 Ω·cm at 100℃. 15 Ω·cm, volume resistivity at 200℃ is not less than 10 14 Ω·cm. At 300℃, its volume resistivity is not less than 10 Ω·cm. 13 Its volume resistivity is not less than 10 Ω·cm at 400℃. 11 Its volume resistivity is not less than 10 Ω·cm at 500℃. 10 Its volume resistivity is not less than 10 Ω·cm at 600℃. 9 Its volume resistivity is not less than 10 Ω·cm at 650℃. 8 Its thermal conductivity is Ω·cm, and at 650℃ it is higher than 65W / mK.

[0265] The third ceramic layer has a room temperature thermal conductivity of 40–100 W / mK and a room temperature volume resistivity of not less than 10 Ω·mK. 16 Its volume resistivity is Ω·cm, which slowly decreases with increasing temperature, and is not less than 10 Ω·cm at 100℃. 15 Ω·cm, volume resistivity at 200℃ is not less than 10 14 Ω·cm. At 300℃, its volume resistivity is not less than 10 Ω·cm. 12 Its volume resistivity is not less than 10 Ω·cm at 400℃. 10 Its volume resistivity is not less than 10 Ω·cm at 500℃. 9Its volume resistivity is not less than 10 Ω·cm at 600℃. 8 Its volume resistivity is not less than 10 Ω·cm at 650℃. 7 Its thermal conductivity is Ω·cm, and at 650℃ it is 10~20W / mK.

[0266] The present invention relates to an aluminum nitride electrostatic chuck with different functional ceramic layers. After hot pressing and sintering, the first ceramic layer has an aluminum nitride matrix with a grain size of <4μm, and a second phase is uniformly dispersed between the aluminum nitride grains with a grain size of <2μm; the second ceramic layer has an aluminum nitride matrix with a grain size of <4μm, and a second phase is uniformly dispersed between the aluminum nitride grains with a grain size of <2μm; the third ceramic layer has an aluminum nitride matrix with a grain size of <4μm, and a second phase is uniformly dispersed between the aluminum nitride grains with a grain size of <2μm.

[0267] The present invention relates to an aluminum nitride electrostatic chuck with different functional ceramic layers. After integral sintering, each ceramic layer has a different chemical composition, crystal phase composition, and thermal and electrical properties, thereby achieving different functional focuses for each ceramic layer. This solves the problem that a single homogeneous ceramic material cannot simultaneously meet the increasingly demanding performance requirements of electrostatic chucks. Therefore, the present invention has great industrial value.

[0268] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. An aluminum nitride electrostatic chuck having different functional ceramic layers, characterized by, The application relates to a ceramic electrode, which comprises a first ceramic layer, a static electrode, a second ceramic layer, a heating electrode and a third ceramic layer, the static electrode is located between the first ceramic layer and the second ceramic layer, the heating electrode is located between the second ceramic layer and the third ceramic layer, the first ceramic layer, the second ceramic layer and the third ceramic layer are different in composition and content, the first ceramic layer comprises aluminum nitride, a sintering aid and a resistance adjusting agent, the amount of the sintering aid is 0.1-4% of the mass of the aluminum nitride, the amount of the resistance adjusting agent is 0.1-2% of the mass of the aluminum nitride, the grain size of the aluminum nitride is 500-900 nm, the thermal conductivity of the first ceramic layer at room temperature is greater than 180 W / (mK), the bulk resistivity at room temperature is not less than 10 16 Ω*cm, the thermal conductivity at 650 DEG C is higher than 45 W / (mK), the bulk resistivity is not less than 10 9 Ω*cm; the thermal conductivity of the second ceramic layer at room temperature is greater than 195 W / (mK), the bulk resistivity at room temperature is not less than 10 16 Ω*cm, the thermal conductivity at 650 DEG C is higher than 65 W / (mK), the bulk resistivity is not less than 10 8 Ω*cm; the thermal conductivity of the third ceramic layer at room temperature is 40-100 W / (mK), the bulk resistivity at room temperature is not less than 10 16 Ω*cm, the thermal conductivity at 650 DEG C is 10-20 W / (mK), the bulk resistivity is not less than 10 7 Ω*cm.

2. The aluminum nitride electrostatic chuck of claim 1 wherein, The aluminum nitride grain size is 600-900 nm.

3. The aluminum nitride electrostatic chuck of claim 1 wherein, The second ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid is 1-5% of the mass of aluminum nitride; and / or, the third ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid is 1-10% of the mass of aluminum nitride.

4. The aluminum nitride electrostatic chuck of claim 1 wherein, The amount of sintering aid in the first ceramic layer is 0.5-3% of the mass of aluminum nitride, and the amount of resistance adjusting agent is 0.1-0.5% of the mass of aluminum nitride; and / or, the second ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid in the second ceramic layer is 2-5% of the mass of aluminum nitride; and / or, the third ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid in the third ceramic layer is 5-10% of the mass of aluminum nitride.

5. The aluminum nitride electrostatic chuck of claim 1 wherein, The amount of sintering aid in the first ceramic layer is 1.0-2.6% of the mass of aluminum nitride, and the amount of resistance adjusting agent is 0.1-0.4% of the mass of aluminum nitride, wherein the aluminum nitride grain size is 600-800 nm.

6. The aluminum nitride electrostatic chuck of claim 1 wherein, The sintering aid is one or more combinations of alkaline earth oxides and rare earth oxides, and the resistance adjusting agent is one or more combinations of nickel, titanium, titanium oxide, and titanium nitride.

7. The aluminum nitride electrostatic chuck of claim 1 wherein, The sintering aid is one or more combinations of magnesium oxide, calcium oxide, yttrium oxide, and samarium oxide, and the resistance adjusting agent is one or more combinations of nickel, titanium, titanium oxide, and titanium nitride.

8. The aluminum nitride electrostatic chuck of claim 1 wherein, The heating electrode is selected from metal paste or metal wire of tungsten, molybdenum, nickel, and platinum; and / or, the static electrode is selected from metal paste or metal wire of molybdenum, tungsten, and palladium.

9. An aluminum nitride electrostatic chuck, characterized by, The first ceramic layer, the static electrode, the second ceramic layer, the heating electrode, and the third ceramic layer are sequentially subjected to step-by-step hydraulic treatment, and then combined together by cold isostatic pressing to be integrally pressed and sintered to form, and the static electrode and the heating electrode are encapsulated in the ceramic layers, wherein the aluminum nitride grain size of the main body material of the first ceramic layer is 500-900 nm.

10. The aluminum nitride electrostatic chuck of claim 9 wherein, The first ceramic layer comprises aluminum nitride, sintering aid, and resistance adjusting agent components, the amount of sintering aid is 0.1-4% of the mass of aluminum nitride, and the amount of resistance adjusting agent is 0.1-2% of the mass of aluminum nitride; and / or, the second ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid is 1-5% of the mass of aluminum nitride; and / or, the third ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid is 1-10% of the mass of aluminum nitride.

11. The aluminum nitride electrostatic chuck of claim 9, wherein, The first ceramic layer comprises aluminum nitride, sintering aid, and resistance adjusting agent components, the amount of sintering aid in the first ceramic layer is 0.5-3% of the mass of aluminum nitride, and the amount of resistance adjusting agent is 0.1-0.5% of the mass of aluminum nitride; and / or, the second ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid in the second ceramic layer is 2-5% of the mass of aluminum nitride; and / or, the third ceramic layer comprises aluminum nitride and sintering aid components, and the amount of sintering aid in the third ceramic layer is 5-10% of the mass of aluminum nitride.

12. The aluminum nitride electrostatic chuck of claim 9, wherein, The first ceramic layer comprises aluminum nitride, a sintering aid and a resistance adjusting agent, the sintering aid accounts for 1.0-2.6% of the mass of the aluminum nitride, and the resistance adjusting agent accounts for 0.1-0.4% of the mass of the aluminum nitride, wherein the grain size of the aluminum nitride is 600-800 nm.

13. The aluminum nitride electrostatic chuck of claim 10 wherein, The sintering aid is one or a combination of alkaline earth oxides and rare earth oxides, and the resistance adjusting agent is one or a combination of nickel, titanium, titanium oxide and titanium nitride.

14. The aluminum nitride electrostatic chuck of claim 10 wherein, The sintering aid is one or a combination of magnesium oxide, calcium oxide, yttrium oxide and samarium oxide, and the resistance adjusting agent is one or a combination of nickel, titanium, titanium oxide and titanium nitride.

15. The aluminum nitride electrostatic chuck of claim 9, wherein, The heating electrode is selected from metal paste or wire of tungsten, molybdenum, nickel and platinum; and / or, the static electrode is selected from metal paste or wire of molybdenum, tungsten and palladium.

16. A method of manufacturing an aluminum nitride electrostatic chuck as claimed in any one of claims 1-15, characterized by, The method comprises the following steps: (1) ceramic layer powder preparation: providing ceramic layer powders of the first ceramic layer, the second ceramic layer and the third ceramic layer; (2) step-by-step hydraulic treatment: filling the powder of the third ceramic layer into a hydraulic mold, first vibrating the powder to be compacted, then repeatedly pressing under a pressure of 5-10 MPa and keeping the pressure for 5-10 minutes, and then laying or printing the heating electrode on the surface thereof; filling the powder of the second ceramic layer into a hydraulic mold, vibrating the powder to be compacted, then repeatedly pressing under a pressure of 10-15 MPa and keeping the pressure for 10-15 minutes, so as to combine the second ceramic layer with the third ceramic layer and the heating electrode, and then laying or printing the static electrode on the surface thereof; filling the powder of the first ceramic layer into a hydraulic mold, vibrating the powder to be compacted, then repeatedly pressing under a pressure of 15-25 MPa and keeping the pressure for 15-20 minutes, so as to combine the first ceramic layer with the second ceramic layer and the static electrode. (3) cold isostatic pressing treatment: taking out the ceramic layers as a whole and densifying them by cold isostatic pressing treatment; (4) one-step sintering forming: transferring the densified ceramic layers to a hot-pressing furnace and one-step sintering forming by hot pressing.

17. A method of manufacturing an aluminum nitride electrostatic chuck as recited in claim 16, wherein, The specific steps of the step-by-step hydraulic treatment are as follows: filling the powder of the third ceramic layer into a hydraulic mold, first vibrating the powder to be compacted, then repeatedly pressing under a pressure of 5-10 MPa and keeping the pressure for 5-10 minutes, and then laying or printing the heating electrode on the surface thereof; filling the powder of the second ceramic layer into a hydraulic mold, vibrating the powder to be compacted, then repeatedly pressing under a pressure of 10-15 MPa and keeping the pressure for 10-15 minutes, so as to combine the second ceramic layer with the third ceramic layer and the heating electrode, and then laying or printing the static electrode on the surface thereof; filling the powder of the first ceramic layer into a hydraulic mold, vibrating the powder to be compacted, then repeatedly pressing under a pressure of 15-25 MPa and keeping the pressure for 15-20 minutes, so as to combine the first ceramic layer with the second ceramic layer and the static electrode.

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