Electrostatic chuck and method of manufacturing the same

Abstract

This invention relates to an electrostatic chuck and its preparation method, specifically to the semiconductor field. The electrostatic chuck comprises: a first ceramic layer, an electrode layer, and a second ceramic layer sequentially disposed on the working surface of a substrate. The electrode layer comprises, by mass percentage: 80-90% tungsten, with the balance being molybdenum. The second ceramic layer comprises, by mass percentage: 70-80% alumina, 10-15% aluminum nitride, with the balance being yttrium oxide. The electrostatic chuck provided by this invention, by optimizing the composition of the surface layer and electrode layer, can significantly improve the adsorption force of the electrostatic chuck, thereby ensuring the firm adsorption of large-size wafers and ensuring efficient processing.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more specifically to an electrostatic chuck and its preparation method. Background Technology

[0002] Electrostatic chucks play a crucial role in dry etching systems, and current etching equipment commonly uses them as the lower electrode. As etching progresses, the wafer or glass is gradually heated by plasma. Because the adhesion rate of reactants is highly dependent on temperature, high-precision etching requires precise control of the wafer temperature. Electrostatic chucks utilize electrostatic adsorption to hold the wafer or glass and precisely control its temperature during the etching process.

[0003] CN120303779A discloses an electrostatic chuck device comprising: an electrostatic chuck component comprising a ceramic material; a base comprising silicon carbide as a material; and a bonding layer comprising a metal material and bonding the electrostatic chuck component and the base. When the entire electrostatic chuck component is 100% by volume, the electrostatic chuck component comprises more than 50% by volume of alumina, and when the entire base is 100% by volume, the base comprises more than 75% by volume and less than 100% by volume of silicon carbide.

[0004] CN121035037A discloses an electrostatic chuck belonging to the field of semiconductor technology, comprising: a ceramic substrate including a main adsorption surface for adsorbing wafers; an adsorption electrode embedded inside the ceramic substrate, the adsorption electrode comprising a metal conductive material and other materials for generating a liquid phase to promote sintering, the amount of the other materials added being between 0.2-1.5 wt% relative to the amount of the metal conductive material added; the average grain size of the other materials being smaller than the average grain size of the ceramic substrate.

[0005] However, electrostatic chucks still have drawbacks in use, such as poor adsorption force, inability to effectively adsorb large-sized wafers, and easy breakdown under high voltage. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide an electrostatic chuck and its preparation method, so as to solve the defects of the electrostatic chuck in use, such as poor adsorption force, inability to effectively adsorb large-size wafers, and surface roughness leading to scratches on the workpiece or residual particles.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an electrostatic chuck, the electrostatic chuck comprising:

[0009] A first ceramic layer, an electrode layer, and a second ceramic layer are sequentially disposed on the working surface of the substrate;

[0010] The electrode layer comprises, by mass percentage: 80-90% tungsten, with the balance being molybdenum;

[0011] The second ceramic layer comprises, by mass percentage: 70-80% alumina, 10-15% aluminum nitride, and the balance being yttrium oxide.

[0012] The electrostatic chuck provided by this invention, by optimizing the composition of the surface layer and electrode layer, can significantly improve the adsorption force of the electrostatic chuck, thereby ensuring the firm adsorption of large-size wafers and ensuring the efficient execution of the processing.

[0013] As a preferred embodiment of the present invention, the first ceramic layer comprises: aluminum nitride and / or aluminum oxide.

[0014] As a preferred embodiment of the present invention, the thickness of the first ceramic layer is 200-800 μm.

[0015] As a preferred embodiment of the present invention, the thickness of the electrode layer is 20-60 μm.

[0016] As a preferred embodiment of the present invention, the thickness of the second ceramic layer is 200-800 μm.

[0017] In a second aspect, the present invention provides a method for preparing an electrostatic chuck as described in the first aspect, the method comprising:

[0018] The first ceramic layer, the electrode layer, and the second ceramic layer are sequentially sprayed onto the substrate.

[0019] As a preferred embodiment of the present invention, the powder used in the first ceramic layer sputtering has a D50 of 20-30 μm.

[0020] Preferably, the power of the first ceramic layer sputtering is 40-50kW.

[0021] Preferably, the gas sprayed into the first ceramic layer comprises argon and hydrogen in a volume ratio of (3-5):1.

[0022] As a preferred technical solution of the present invention, the powder used in the electrode layer sputtering has a D50 of 10-50 μm.

[0023] Preferably, the power of the electrode layer melting and spraying is 30-50kW.

[0024] Preferably, the gas used for melting and spraying the electrode layer comprises argon and hydrogen in a volume ratio of (3-5):1.

[0025] As a preferred embodiment of the present invention, the powder used in the second ceramic layer sputtering has a D50 of 10-20 μm.

[0026] Preferably, the power of the second ceramic layer sputtering is 40-50kW.

[0027] Preferably, the gas sprayed into the second ceramic layer comprises argon and hydrogen in a volume ratio of (3-5):1.

[0028] As a preferred embodiment of the present invention, the substrate is cleaned.

[0029] Preferably, the cleaning includes one or a combination of at least two of the following: chemical cleaning, plasma cleaning, or sandblasting.

[0030] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0031] The electrostatic chuck provided by this invention significantly improves the adsorption force of the electrostatic chuck by optimizing the material composition of the functional layer, while ensuring that it will not break down under high voltage. Furthermore, by further optimizing and controlling the particle size of the powder used in the preparation process, the adsorption force can be further improved, thereby ensuring the performance of the electrostatic chuck.

[0032] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0033] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0034] Electrostatic chucks play a crucial role in dry etching systems, and current etching equipment commonly uses them as the lower electrode. As etching progresses, the wafer or glass is gradually heated by plasma. Since the adhesion rate of reactants is highly dependent on temperature, high-precision etching requires precise control of the wafer temperature. Electrostatic chucks utilize electrostatic adsorption of the wafer or glass and precisely control its temperature during etching. However, current electrostatic chucks still suffer from drawbacks such as poor adsorption force, ineffective adsorption of large wafers, and surface roughness leading to scratches or residual particles. Therefore, this invention optimizes the functional layer parameters and fabrication process of the electrostatic chuck to improve its performance, as detailed below:

[0035] I. This embodiment provides an electrostatic chuck, the electrostatic chuck comprising:

[0036] The first ceramic layer, the electrode layer, and the second ceramic layer are sequentially disposed on the working surface of the substrate.

[0037] In this invention, the material of the substrate is selected reasonably according to the conventional requirements in the field, such as aluminum or aluminum alloy, such as Al6061.

[0038] The electrode layer comprises, by mass percentage, 80-90% tungsten and the balance being molybdenum. For example, it can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or 90%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0039] The second ceramic layer comprises, by mass percentage: 70-80% aluminum oxide, 10-15% aluminum nitride, and the balance being yttrium oxide.

[0040] In this invention, the alumina in the second ceramic layer is 70-80% by mass percentage, for example, it can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0041] In this invention, the aluminum nitride in the second ceramic layer is 10-15% by mass percentage, for example, it can be 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0042] The first ceramic layer comprises aluminum nitride and / or aluminum oxide.

[0043] The thickness of the first ceramic layer is 200-800μm, for example, it can be 200μm, 260μm, 320μm, 380μm, 440μm, 500μm, 560μm, 620μm, 680μm, 740μm or 800μm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0044] The thickness of the electrode layer is 20-60 μm, for example, it can be 20 μm, 24 μm, 28 μm, 32 μm, 36 μm, 40 μm, 44 μm, 48 μm, 52 μm, 56 μm or 60 μm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0045] The thickness of the second ceramic layer is 200-800μm, for example, it can be 200μm, 260μm, 320μm, 380μm, 440μm, 500μm, 560μm, 620μm, 680μm, 740μm or 800μm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0046] II. This embodiment provides a method for preparing an electrostatic chuck, the method comprising:

[0047] The first ceramic layer, the electrode layer, and the second ceramic layer are sequentially sprayed onto the substrate.

[0048] The powder used in the first ceramic layer sputtering has a D50 of 20-30 μm, for example, it can be 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm or 30 μm, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0049] The power of the first ceramic layer sputtering is 40-50kW, for example, it can be 40kW, 41kW, 42kW, 43kW, 44kW, 45kW, 46kW, 47kW, 48kW, 49kW or 50kW, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0050] The gas used for sputtering the first ceramic layer includes argon and hydrogen in a volume ratio of (3-5):1, such as 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, or 5:1, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0051] The powder used in the electrode layer sputtering has a D50 of 10-50 μm, for example, it can be 10 μm, 14 μm, 18 μm, 22 μm, 26 μm, 30 μm, 34 μm, 38 μm, 42 μm, 46 μm or 50 μm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0052] The power of the electrode layer sputtering is 30-50kW, for example, it can be 30kW, 32kW, 34kW, 36kW, 38kW, 40kW, 42kW, 44kW, 46kW, 48kW or 50kW, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0053] The gas used for melting and spraying the electrode layer includes argon and hydrogen in a volume ratio of (3-5):1, such as 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, or 5:1, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0054] The powder used in the second ceramic layer sputtering has a D50 of 10-20 μm, for example, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0055] The power of the second ceramic layer sputtering is 40-50kW, for example, it can be 40kW, 41kW, 42kW, 43kW, 44kW, 45kW, 46kW, 47kW, 48kW, 49kW or 50kW, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0056] The gas used for sputtering the second ceramic layer includes argon and hydrogen in a volume ratio of (3-5):1, such as 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, or 5:1, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0057] In this invention, the powders used in each melting process are selected according to the composition of each layer, such as alumina powder, aluminum nitride powder, yttrium oxide powder, tungsten powder, molybdenum powder, etc. Regarding the particle size limitation, it can be the individual particle size limitation of each powder, or the particle size limitation of the mixture of raw material powders of each layer. The specific selection can be made reasonably according to actual needs.

[0058] The substrate is cleaned.

[0059] In this invention, the purpose of cleaning is to remove impurities from the substrate surface, such as oxides, rust, dust, oil, and salt stains, which can affect the functional layer setup. The specific cleaning process is designed according to conventional requirements in the field to achieve the surface requirements for melt spraying.

[0060] In this invention, cleaning can be performed either before the spraying process or after each spraying step.

[0061] The cleaning process includes one or a combination of at least two of the following: chemical cleaning, plasma cleaning, or sandblasting.

[0062] III. To illustrate the effects of the electrostatic chuck provided by this invention, the following example is used for explanation:

[0063] Example 1

[0064] This embodiment provides an electrostatic chuck, the electrostatic chuck comprising:

[0065] A first ceramic layer, an electrode layer, and a second ceramic layer are sequentially disposed on the working surface of the substrate (Al6061 aluminum alloy);

[0066] The first ceramic layer is aluminum oxide with a thickness of 500 μm;

[0067] The electrode layer comprises, by mass percentage: 85% tungsten, with the balance being molybdenum, and has a thickness of 40 μm;

[0068] The second ceramic layer comprises, by mass percentage: 75% alumina, 12% aluminum nitride, and the balance being yttrium oxide; its thickness is 500 μm.

[0069] The preparation process is as follows:

[0070] The first ceramic layer, the electrode layer, and the second ceramic layer are sequentially sprayed onto the substrate.

[0071] The powder used in the first ceramic layer sputtering is alumina powder with a D50 of 25 μm; the power of the first ceramic layer sputtering is 45 kW; the gas used in the first ceramic layer sputtering includes argon and hydrogen in a volume ratio of 4:1.

[0072] The powders used in the electrode layer sputtering are tungsten powder and molybdenum powder, each with a D50 of 30 μm; the power of the electrode layer sputtering is 40 kW; the gas used in the electrode layer sputtering includes argon and hydrogen in a volume ratio of 4:1.

[0073] The powders used in the second ceramic layer sputtering are alumina powder, aluminum nitride powder, and yttrium oxide powder, each with a D50 of 15 μm; the power of the second ceramic layer sputtering is 45 kW; the gas used in the second ceramic layer sputtering includes argon and hydrogen in a volume ratio of 4:1.

[0074] Example 2

[0075] This embodiment provides an electrostatic chuck, the electrostatic chuck comprising:

[0076] A first ceramic layer, an electrode layer, and a second ceramic layer are sequentially disposed on the working surface of the substrate (Al6061 aluminum alloy);

[0077] The first ceramic layer comprises: aluminum oxide with a thickness of 200 μm;

[0078] The electrode layer comprises, by mass percentage: 90% tungsten, the balance being molybdenum, and has a thickness of 60 μm;

[0079] The second ceramic layer comprises, by mass percentage: 80% alumina, 15% aluminum nitride, and the balance being yttrium oxide; its thickness is 800 μm.

[0080] The preparation process is as follows:

[0081] The first ceramic layer, the electrode layer, and the second ceramic layer are sequentially sprayed onto the substrate.

[0082] The powder used in the first ceramic layer sputtering is alumina powder with a D50 of 20 μm; the power of the first ceramic layer sputtering is 40 kW; the gas used in the first ceramic layer sputtering includes argon and hydrogen in a volume ratio of 3:1.

[0083] The powders used in the electrode layer sputtering are tungsten powder and molybdenum powder, each with a D50 of 10 μm; the power of the electrode layer sputtering is 30 kW; the gas used in the electrode layer sputtering includes argon and hydrogen in a volume ratio of 3:1.

[0084] The powders used in the second ceramic layer sputtering are alumina powder, aluminum nitride powder, and yttrium oxide powder, each with a D50 of 10 μm; the power of the second ceramic layer sputtering is 40 kW; the gas used in the second ceramic layer sputtering includes argon and hydrogen in a volume ratio of 3:1.

[0085] Example 3

[0086] This embodiment provides an electrostatic chuck, the electrostatic chuck comprising:

[0087] A first ceramic layer, an electrode layer, and a second ceramic layer are sequentially disposed on the working surface of the substrate (Al6061 aluminum alloy);

[0088] The first ceramic layer comprises: aluminum oxide with a thickness of 800 μm;

[0089] The electrode layer comprises, by mass percentage: 80% tungsten, the balance being molybdenum, and has a thickness of 20 μm;

[0090] The second ceramic layer comprises, by mass percentage: 70% alumina, 10% aluminum nitride, and the balance being yttrium oxide; its thickness is 200 μm.

[0091] The preparation process is as follows:

[0092] The first ceramic layer, the electrode layer, and the second ceramic layer are sequentially sprayed onto the substrate.

[0093] The powder used in the first ceramic layer sputtering is alumina powder with a D50 of 30 μm; the power of the first ceramic layer sputtering is 50 kW; the gas used in the first ceramic layer sputtering includes argon and hydrogen in a volume ratio of 5:1.

[0094] The powders used in the electrode layer sputtering are tungsten powder and molybdenum powder, each with a D50 of 50 μm; the power of the electrode layer sputtering is 50 kW; the gas used in the electrode layer sputtering includes argon and hydrogen in a volume ratio of 5:1.

[0095] The powders used in the second ceramic layer sputtering are alumina powder, aluminum nitride powder, and yttrium oxide powder, each with a D50 of 20 μm; the power of the second ceramic layer sputtering is 50 kW; the gas used in the second ceramic layer sputtering includes argon and hydrogen in a volume ratio of 5:1.

[0096] Example 4

[0097] The only difference from Example 1 is that the powder used in the second ceramic layer sputtering has a D50 of 30 μm.

[0098] Example 5

[0099] The only difference from Example 1 is that the powder used in the second ceramic layer sputtering has a D50 of 8 μm.

[0100] Comparative Example 1

[0101] The only difference from Example 1 is that the electrode layer is a tungsten layer.

[0102] Comparative Example 2

[0103] The only difference from Example 1 is that the electrode layer, by mass percentage, comprises 70% tungsten and the balance is molybdenum.

[0104] Comparative Example 3

[0105] The only difference from Example 1 is that the electrode layer, by mass percentage, comprises 95% tungsten and the balance is molybdenum.

[0106] Comparative Example 4

[0107] The only difference from Example 1 is that aluminum nitride in the second ceramic layer is replaced with aluminum oxide.

[0108] Comparative Example 5

[0109] The only difference from Example 1 is that aluminum nitride in the second ceramic layer is replaced with yttrium oxide.

[0110] Comparative Example 6

[0111] The only difference from Example 1 is that the second ceramic layer comprises, by mass percentage: 75% aluminum oxide, 8% aluminum nitride, and the balance being yttrium oxide.

[0112] Comparative Example 7

[0113] The only difference from Example 1 is that the second ceramic layer comprises, by mass percentage: 75% aluminum oxide, 20% aluminum nitride, and the balance being yttrium oxide.

[0114] The electrostatic chucks obtained in the above embodiments and comparative examples were subjected to adsorption force and dielectric strength tests, and the results are shown in Table 1 below.

[0115] The sample used for testing electrostatic adsorption force was 500×500mm. 2 The electrostatic chuck was measured using a DST-200N push-pull tester. Here, the applied voltage was set to 1.5 kV. Dielectric strength, representing the highest electric field strength a material can withstand to avoid breakdown, is typically expressed as the ratio of the breakdown voltage of the dielectric layer sample to its thickness, in kV / mm.

[0116] Table 1

[0117]

[0118] As shown in Table 1, the electrostatic chuck provided by this invention significantly improves the adsorption force of the electrostatic chuck by optimizing the material composition of the functional layer, while ensuring that it will not break down under high voltage (adsorption force ≥ 73.7 N, dielectric strength ≥ 17.56 kV / mm). Furthermore, by further optimizing and controlling the particle size of the powder used in the preparation process, the adsorption force can be further improved (adsorption force ≥ 80.9 N, dielectric strength ≥ 18.65 kV / mm), thereby ensuring the performance of the electrostatic chuck.

[0119] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0120] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0121] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. An electrostatic chuck, characterized in that, The electrostatic chuck includes: A first ceramic layer, an electrode layer, and a second ceramic layer are sequentially disposed on the working surface of the substrate; The electrode layer comprises, by mass percentage: 80-90% tungsten, with the balance being molybdenum; The second ceramic layer comprises, by mass percentage: 70-80% alumina, 10-15% aluminum nitride, and the balance being yttrium oxide.

2. The electrostatic chuck as described in claim 1, characterized in that, The first ceramic layer comprises: aluminum nitride and / or aluminum oxide.

3. The electrostatic chuck as described in claim 1, characterized in that, The thickness of the first ceramic layer is 200-800 μm.

4. The electrostatic chuck as described in claim 1, characterized in that, The thickness of the electrode layer is 20-60 μm.

5. The electrostatic chuck as described in claim 1, characterized in that, The thickness of the second ceramic layer is 200-800 μm.

6. The method for preparing the electrostatic chuck according to any one of claims 1-5, characterized in that, The preparation method includes: The first ceramic layer, the electrode layer, and the second ceramic layer are sequentially sprayed onto the substrate.

7. The preparation method according to claim 6, characterized in that, The powder used in the first ceramic layer sputtering has a D50 of 20-30 μm; Preferably, the power of the first ceramic layer sputtering is 40-50kW; Preferably, the gas sprayed into the first ceramic layer comprises argon and hydrogen in a volume ratio of (3-5):

1.

8. The preparation method according to claim 6, characterized in that, The powder used in the electrode layer sputtering has a D50 of 10-50 μm; Preferably, the power of the electrode layer sputtering is 30-50kW; Preferably, the gas used for electrode layer melting includes argon and hydrogen in a volume ratio of (3-5):

1.

9. The preparation method according to claim 6, characterized in that, The powder used in the second ceramic layer spraying has a D50 of 10-20 μm; Preferably, the power of the second ceramic layer sputtering is 40-50kW; Preferably, the gas sprayed into the second ceramic layer comprises argon and hydrogen in a volume ratio of (3-5):

1.

10. The preparation method according to claim 6, characterized in that, The substrate is cleaned; Preferably, the cleaning includes one or a combination of at least two of the following: chemical cleaning, plasma cleaning, or sandblasting.

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