KR20210039966A - Wafer chuck, method for producing the same, and exposure apparatus - Google Patents

Abstract

A wafer chuck of the present invention includes a base made of a ceramic containing silicon carbide. The base has an oxidation treatment layer, and a film made of diamond-like carbon (DLC) is formed on the outermost surface of the base. According to the present invention the wafer chuck in an exposure apparatus can improve durability by reducing dust generation and reducing wear.

Description

A wafer chuck, a wafer chuck manufacturing method, and an exposure apparatus TECHNICAL FIELD [WAFER CHUCK, METHOD FOR PRODUCING THE SAME, AND EXPOSURE APPARATUS]

The present invention relates to a wafer chuck member used to support a substrate in a lithographic process process for manufacturing a semiconductor device or the like.

As a wafer chuck member used to support a substrate in a lithographic process process for manufacturing a semiconductor device, it is known to use a ceramic material such as a silicon carbide-based ceramic or a silicon nitride-based ceramic. Among them, silicon carbide-based ceramics are resistant to degradation in durability due to high mechanical strength, and a decrease in positioning precision of a semiconductor wafer caused by temperature changes due to high thermal conductivity is small. Therefore, the silicon carbide-based ceramic is suitable for a wafer chuck member. However, when grinding and polishing a silicon carbide member into a predetermined shape for use as a wafer chuck material, fine microcracks are generated on the surface, and fine silicon carbide-based ceramic particles are separated as dust from the fine microcracks. It is known. Such dust (waste) deposited in the circuit portion of the semiconductor device causes poor circuit insulation, short circuits, or other problems.

Therefore, it is known that a polycrystalline diamond film or a hard carbon film is formed on the surface of the wafer chuck in order to prevent dust from being generated from the wafer chuck (Japanese Patent Laid-Open No. Hei 6-204324).

For silicon carbide-based ceramics for use in motor components, it is also known that heat treatment at a temperature in the range of 400°C to 1400°C in air or in an oxidizing atmosphere can reduce dust generation (Japanese Patent Publication No. 2002-47078). This is because heat treatment in air or in an oxidizing atmosphere forms a surface film containing an oxide.

However, the generation of dust is reduced only on the surface of the wafer chuck on which the polycrystalline diamond film or the hard carbon film is formed, and the generation of dust cannot be reduced on the side or back surface on which such a film is not formed.

Heat treatment of the silicon carbide-based ceramic at a temperature in the range of 400 °C to 1400 °C in air or in an oxidizing atmosphere can reduce dust generation. However, the surface film containing the oxide thus formed has a lower mechanical strength and a higher coefficient of friction than a silicon carbide-based ceramic. Deterioration in durability of the wafer chuck due not only to the generation of dust due to abrasion but also due to the lowered flatness due to wear, is not a big problem for motor components, but it is a problem for members that require a flatness of the order of nanometers, such as those for wafer chuck . Although the silicon carbide-based ceramic member has high wear resistance, sliding on the wafer member for a long period of time causes wear and impairs exposure performance such as positioning accuracy or resolution.

A first aspect of the present invention provides a wafer chuck comprising a base made of a ceramic containing silicon carbide, the base having an oxidation treatment layer, and a film made of diamond-like carbon (DLC). It is formed on the outermost surface of the base.

A second aspect of the present invention provides a method of manufacturing a wafer chuck comprising the step of oxidizing a surface of a base made of a ceramic containing silicon carbide, and forming a film made of diamond-like carbon (DLC).

Additional features of the present invention will be clearly understood from the following description of exemplary embodiments with reference to the accompanying drawings.

1 is a schematic diagram of a film forming apparatus according to the present invention.
2A is a schematic diagram of a wafer chuck according to the present invention.
2B is a schematic diagram of a wafer chuck according to the present invention.
3A is a schematic diagram of a wafer chuck according to the present invention.
3B is a schematic diagram of a wafer chuck according to the present invention.
3C is a schematic diagram of a wafer chuck according to the present invention.
4 is a schematic diagram of a lithographic process in an exposure apparatus according to the present invention.

Hereinafter, embodiments of the present invention will be described in more detail.

The wafer chuck is a member that holds a semiconductor wafer in a lithographic process apparatus of a semiconductor device. The wafer chuck has a protruding pin portion formed at intervals of several hundred micrometers to several millimeters and having a height and diameter of several tens to several hundred micrometers on a surface of a wafer chuck to which a semiconductor wafer contacts. Further, the wafer chuck includes holes and grooves for adsorbing a semiconductor wafer.

2A and 2B are schematic views of a wafer chuck for use in the present invention. 2A is a plan view, and FIG. 2B is a side view. The wafer chuck 21 includes a suction hole 22 passing through the wafer chuck 21 in the thickness direction. The suction hole 22 is used to suck a wafer (not shown) such as a silicon wafer. Although 27 radially arranged suction holes 22 are shown in the figure, the size, number and arrangement of the suction holes 22 can be adjusted to properly suction and fix the wafer on the chuck 21. After completing the lithography process of the wafer fixed to the chuck 21, the suction of the wafer is stopped, and a lift pin (not shown) is raised from the back surface of the chuck 21 through the lift pin hole 23 so that the chuck 21 Separate the wafer from Although three circumferentially arranged lift pin holes 23 are shown in the figure, the size, number and arrangement of the lift pin holes 23 may be adjusted to properly separate the wafer from the chuck 21. The wafer wafer is held on the upper surface 24 of the wafer chuck 21. A protruding pin portion (not shown) is formed on the upper surface 24. The wafer chuck 21 may be fixed to the wafer stage through the flange 25 of the wafer chuck 21.

3A to 3C are schematic views of a diamond-like carbon film and an adhesive layer formed on a base. The protruding pin portion 32 is formed on the base 31. 3A to 3C schematically show the shape of the pin portion 32, the height and width of the pin portion 32 and the distance between the pin portions 32 are not drawn to scale. To be precise, as described above, the pin portions typically have a height and diameter of tens to hundreds of micrometers and are arranged at intervals of several hundred micrometers to several millimeters. In the present invention, as shown in FIG. 3B, a film made of diamond-like carbon (DLC) (diamond-like carbon film) 33 is the entire front surface of the base 31 (top surface, side surface, and bottom surface of the pin portion). ) Can be formed on. In addition, in the present invention, as shown in FIG. 3C, the adhesive layer 34 and the diamond-shaped carbon film 33 may be formed on the front surface of the base 31 in the order of substrates. Thus, a film made of diamond-like carbon (DLC) is formed on the outermost surface of the wafer chuck.

4 is a schematic diagram of a lithographic process of an exposure apparatus, which is an example of an apparatus including a wafer chuck according to the present invention. In the drawing, the exposure light source 41 may be a mercury lamp, a laser light source such as a KrF laser or an ArF laser, or an X-ray light source. The condensing lens 42 may convert light emitted from the light source 41 into parallel light. The mask 43 has a required circuit pattern of a wafer drawn on a surface of a quartz member or the like. The reduction projection lens 44 can reduce the circuit pattern drawn on the mask 43 and project it onto the wafer 45. The wafer 45 may be made of silicon. The required circuit pattern is drawn on a photoresist applied to the surface of the wafer 45 in a lithographic process. The wafer chuck 46 is disposed on a wafer stage (not shown) and may support a wafer 45 such as a silicon wafer. The wafer 45 and the wafer chuck 46 can be continuously moved by the wafer stage, and the wafer 45 can be repeatedly exposed to the circuit pattern. In the schematic diagram of Fig. 4, a circuit pattern is formed in a lithography process using a light source (light). However, the wafer chuck according to the present invention may also be used in the process of transferring micropatterns of tens of nanometers or less by pressing the original mold in, for example, a nanoimprint process.

In the exposure apparatus, the wafer chuck according to the present invention can improve durability by reducing dust generation and reducing wear.

The base used in the wafer chuck according to the present embodiment may have a specific shape, for example, by forming a ceramic material including silicon carbide in a pin shape on the surface of the wafer chuck to which the semiconductor wafer contacts.

The ceramic containing silicon carbide used in this embodiment is a sintered body or polycrystalline body of silicon carbide. In addition to the silicon carbide component, as a sintering aid, beryllium (Be), boron (B), aluminum (Al), and/or a compound thereof (carbide, nitride, oxide) may be used to form a high-density sintered body. Silicon carbide polycrystals can be formed by chemical vapor deposition (CVD) methods. More specifically, for example, by forming a silicon carbide polycrystal having a thickness of several millimeters from silicon tetrachloride gas and methane gas on a graphite base by a thermal CVD method, and removing the graphite base by cutting or evaporation at high temperature, A single body of a crystalline silicon carbide member can be produced. The polycrystalline silicon carbide member formed by the CVD method without containing a sintering aid has a higher purity than that of the sintered body, and has high adhesion to the diamond-like carbon film to be formed. The polycrystalline silicon carbide member has high mechanical strength and thermal conductivity and is suitable for a wafer chuck member. A sintered body mainly composed of silicon carbide and a polycrystalline silicon carbide member formed by the CVD method is referred to as a ceramic including silicon carbide (silicon carbide-based ceramic) in the present invention.

The wafer chuck must have a high flatness, particularly in the pin-shaped portion on the surface of the wafer chuck to which the semiconductor wafer contacts. When grinding or polishing the base into a predetermined shape, fine microcracks are generated on the surface, and fine silicon carbide-based ceramic particles are separated from the fine microcracks as dust (waste). Such dust deposited in the circuit portion of the semiconductor device often causes circuit insulation failure or short circuit.

To solve this problem, in this embodiment, the surface of the base made of ceramic containing silicon carbide is first subjected to oxidation treatment. More specifically, for example, the base is heated for several tens of minutes to tens of hours at a temperature in the range of 300 °C to 700 °C in air or in an oxygen atmosphere. This oxidizes the microcracks on the surface and forms a film (oxidation treatment layer) containing an oxide. The film containing the oxide (oxidized layer) has a thickness in the range of approximately 1 to 100 nm. The oxygen atom concentration in the oxide-containing film (oxidized layer) exceeds 25 atomic%. The oxygen atom concentration in such a film can be measured with an elemental analyzer of an electron microscope. The oxygen atom concentration in the oxidation treatment layer tends to increase with the treatment temperature and treatment time.

Ceramic materials comprising silicon carbide typically have high thermal stability and hardly oxidize at temperatures in the range of approximately 300°C to 700°C. However, the microcracks formed by grinding or polishing have high reactivity due to defects or distortions caused by processing, and can be easily oxidized at low temperatures. The film containing the oxide formed on the microcracks increases the volume of the crack surface portion and covers the microcracks, thereby reducing the detachment of fine particles from the surface. Typically, the higher the oxidation treatment temperature, the thicker the oxide-containing film and the higher the anti-oscillation effect. However, oxidation treatment temperatures of, for example, 1000° C. or higher often cause thermal deformation and result in a wafer chuck with insufficient flatness. Therefore, it is preferable that the oxidation treatment temperature is made as low as about 300°C to 700°C and the treatment time is lengthened (preferably several hours or more). Optimal oxidation treatment conditions for the ceramic sintered body containing silicon carbide are determined according to the particle size before sintering, the sintering state, the type of sintering aid, and the grinding or polishing conditions. Thus, these conditions are properly controlled. Optimal oxidation treatment conditions for the polycrystalline silicon carbide member formed by the CVD method are also determined according to the average particle size of the polycrystalline material and the grinding or polishing conditions. Therefore, these conditions are also properly controlled.

After the oxidation treatment, a film made of diamond-like carbon (DLC) (diamond-like carbon film) is formed.

Diamond-like carbon films are typical coating materials that have high film stress and are easily released, but diamond-like carbon films are known to have relatively high adhesion to silicon carbide members.

However, in the ceramic sintered body containing silicon carbide, an oxidized layer is formed on the surface of the sintering aid under specific oxidation treatment conditions. This often leads to poor adhesion problems between the diamond-like carbon film and the ceramic member comprising silicon carbide and the separation of the diamond-like carbon film. This is because the sintering aid material is more easily oxidized than the silicon carbide material. Therefore, in order to also improve the adhesion of the diamond-like carbon film, it is preferable that the oxidation treatment temperature is as low as about 300°C to 700°C. Under these oxidation treatment conditions, the amount of the sintering aid in the ceramic sintered body containing silicon carbide is generally as small as several weight percent or less, and the adhesion to the diamond-like carbon film is at a practical level.

The polycrystalline silicon carbide member formed by the CVD method that does not contain a sintering aid has no oxidation of the sintering aid portion and the decrease in adhesion to the diamond-like carbon film due to the oxidation treatment is reduced. This is probably because oxidation of the crack portion in the oxidation treatment is mainly caused by a reaction in the silicon carbide crystal grains, and the surface portion in contact with the diamond-like carbon film hardly has an oxidized portion. Also in this respect, the polycrystalline silicon carbide member formed by the CVD method is suitable for the base.

After forming a layer containing at least silicon or carbon, a diamond-like carbon film may be formed on the layer containing at least silicon or carbon to improve adhesion. That is, a layer including at least silicon or carbon and a layer made of diamond-like carbon (diamond-like carbon film) may be sequentially stacked.

After the formation of the amorphous layer containing carbon, silicon, oxygen and hydrogen, a diamond-like carbon film may be formed on the amorphous layer containing carbon, silicon, oxygen and hydrogen to improve adhesion. That is, an amorphous layer including carbon, silicon, oxygen, and hydrogen, and a diamond-like carbon film may be sequentially stacked.

A layer comprising at least silicon or carbon, or an amorphous layer comprising carbon, silicon, oxygen and hydrogen is referred to as an adhesive layer. The adhesive layer is formed to further improve the adhesion between the silicon carbide-based ceramic member and the diamond-like carbon film.

In the present invention, the layer containing at least silicon or carbon includes a silicon film, a silicon nitride film, or a carbide film such as a silicon carbide film or a carbon nitride film. The layer containing at least silicon or carbon may contain oxygen, but the oxygen content is 25 atomic% or less, preferably 20 atomic% or less.

The amorphous layer containing carbon, silicon, oxygen and hydrogen is suitable for the adhesive layer due to its high adhesion to the diamond-like carbon film and small film stress. Each of the carbon atom concentration, silicon atom concentration, oxygen atom concentration, and hydrogen atom concentration in the film may be 5 atomic% or more, and the oxygen atomic concentration may be 20 atomic% or less. The concentration of each element in the film can be measured with an elemental analyzer of an electron microscope.

1 shows a film forming apparatus for forming an adhesive layer and a diamond-like carbon film. The film forming apparatus shown in FIG. 1 is a high frequency plasma chemical vapor deposition (CVD) apparatus. The film forming apparatus used in this embodiment is not limited thereto, and a known ion plating apparatus or sputtering apparatus may be used. In the film forming apparatus in this embodiment, an adhesive layer and a diamond-like carbon film can be formed continuously, but the adhesive layer and a diamond-like carbon film can be formed by other devices. For example, the adhesive layer may be formed by the high-frequency plasma CVD apparatus shown in FIG. 1, and the diamond-like carbon film may be formed by another apparatus such as an ion plating apparatus, a sputtering apparatus, or a cathode arc film forming apparatus. Alternatively, after the adhesive layer is formed by a sputtering apparatus, a diamond-like carbon film may be formed by the high-frequency plasma CVD apparatus shown in FIG. 1.

In Fig. 1, the vacuum chamber 1 is provided with a vacuum pump (not shown) and a vacuum valve (not shown), and can be exhausted at ^{1 x 10 -3 Pa.} The ground electrode 2, which also functions as a showerhead for introducing a source gas, has many openings with a diameter of approximately 1 mm on its bottom surface in the figure. The source gas can be introduced through the opening. The diameter and pitch of the openings are appropriately determined so that the thickness distribution of the film is uniformly formed. Further, the ground electrode 2 functioning as a showerhead for introducing a source gas is also used as a ground electrode. The source gas inlet 3 is coupled to a gas valve, a gas flow controller, and a source gas cylinder (all not shown).

In order to form an amorphous layer containing carbon, silicon, oxygen and hydrogen with this apparatus, a liquid organosilicon compound, for example, can be used as a source gas. Liquid organosilicon compounds can be used by heating tetraethoxysilane or hexamethyldisiloxane (e.g., approximately 40°C) for gasification. These gases can also be diluted with noble gas (argon gas, helium gas, etc.), nitrogen gas, or hydrogen gas.

Various vaporized carbon-comprising gases and liquid organic compounds can be used as the source gas for the diamond-like carbon film. Examples of carbon containing gases include methane, ethane, ethylene, and hydrocarbon gases such as acetylene, carbon monoxide and halogenated carbon. Examples of liquid organic compounds include alcohols such as methanol and ethanol, ketones such as acetone, aromatic hydrocarbons such as benzene and toluene, ethers such as dimethyl ether, and organic acids such as formic acid and acetic acid. These gases can also be diluted with noble gas (argon gas, helium gas, etc.), nitrogen gas, or hydrogen gas. The base 4 is manufactured by processing a base made of a ceramic containing silicon carbide into a specific shape, and oxidizing the base. The base 4 can be disposed on the high frequency introduction electrode 5 which also functions as a substrate holder. The high frequency introduction electrode 5 may be used to apply high frequency power. The high frequency power supply 6 supplies high frequency power to the high frequency introduction electrode 5 which also functions as a substrate holder.

In order to form a film containing at least silicon as an adhesive layer, for example, a silicon target can be sputtered by a known sputtering method to form a silicon film. A gas mixture of argon and nitrogen can be used as a sputtering gas to form a silicon nitride film. The silicon carbide target can also be sputtered to form a silicon carbide film.

In the amorphous layer containing carbon, silicon, oxygen and hydrogen used as the adhesive layer, each of the carbon atom concentration, silicon atom concentration, oxygen atom concentration, and hydrogen atom concentration is at least 5 atomic%. The oxygen atom concentration is 20 atomic% or less. The amorphous layer comprising carbon, silicon, oxygen and hydrogen is also referred to as a C-Si-O-H film. The secondary impurities during film formation may be about 1 atomic% or less of a diluent gas such as nitrogen or argon, or a metal element of a chamber and a substrate holder such as iron or aluminum. In this embodiment, an amorphous layer containing carbon, silicon, oxygen and hydrogen is formed between a ceramic base containing silicon carbide and a diamond-like carbon film, and is used as an intermediate layer for improving adhesion. Carbon and silicon in the layer improve adhesion, and hydrogen and oxygen in the layer reduce film stress and further improve adhesion. At an oxygen atom concentration of 20 atomic% or less, the adhesion property is improved, and at an oxygen atom concentration exceeding 25 atomic%, the adhesion to the diamond-like carbon film is often not improved. The amorphous layer including carbon, silicon, oxygen, and hydrogen may be an amorphous film without crystallinity.

The thickness of the adhesive layer may be appropriately adjusted, for example, in the range of 0.01 μm or more and 1 μm or less, and preferably 0.02 μm or more and 0.4 μm or less.

A film made of diamond-like carbon (DLC) (diamond-like carbon film) is basically amorphous, has high hardness, and is so called because it has high transparency in the infrared region. Films made of diamond-like carbon (DLC) (diamond-like carbon film) are often referred to as hard carbon films, iC films (i-carbon films), or Ta-C films (tetrahedral amorphous carbon films). . A film made of diamond-like carbon (DLC) (a diamond-like carbon film) is composed only of carbon atoms and secondary impurities, or contains hydrogen gas generated from a raw material. Films containing hydrogen gas are often referred to as a-C:H films. The diamond-like carbon film according to the present invention includes an a-C:H film. The secondary impurities may be up to approximately 1 atomic percent of a diluent gas, such as nitrogen, argon, or atmospheric oxygen, or a metallic element of the chamber and substrate holder, such as iron or aluminum. The thickness of the film may be appropriately adjusted, for example, in the range of 0.04 μm or more and 1 μm or less, preferably 0.05 μm or more and 0.4 μm or less.

Yes

The invention is described in detail in the following exemplary embodiments.

Dust amount assessment

In this exemplary embodiment, the amount of dust in the wafer chuck was evaluated by a subsequent method. A base made of ceramic containing silicon carbide ground into a specific shape was placed on a clean bench, and ambient air was introduced by suction into a particle counter to measure dust having a size of 0.1 μm or more. The amount of dust was based on the amount of dust in Comparative Example 1 in which the base made of the ceramic sintered body containing silicon carbide was not subjected to oxidation, and the adhesive layer and the diamond-like carbon film were not formed. The amount of dust in the exemplary embodiment and in other comparative examples was compared.

Evaluation of durability

Durability was evaluated by the pin-on-disk method in the sliding test. Samples were prepared by grinding a material equivalent to a base made of ceramic containing silicon carbide into a flat sheet shape and subjecting the material to various treatments described in the exemplary and comparative examples. The test was performed with a width of 5 mm and a sliding speed of 1 mm/s with a φ8 silicon sphere placed on the sample under a load of 50 g. After the test, the sliding part was inspected for sliding wear marks with an optical microscope or a scanning electron microscope. Samples containing the membrane were examined for separation of the membrane by light microscopy or scanning electron microscopy. The shape of the abrasion marks was measured with an interferometric observation of the surface profile.

Illustrative Example 1

First, a base made of a ceramic sintered body containing ground silicon carbide of a specific shape was placed in a heating furnace, and an oxidation treatment was applied. The base was heated to 400°C in air at a heating rate of 10°C/min, held at 400°C for 5 hours, and then slowly cooled to room temperature over 8 hours. Subsequently, a base made of a ceramic sintered body containing silicon carbide was placed in a high-frequency plasma CVD apparatus as shown in Fig. 1, which was evacuated to ^{1 x 10 -3 Pa by a vacuum pump.} Subsequently, argon gas for plasma cleaning was introduced into the showerhead 2 for introducing a source gas, and the pressure was adjusted to 5 Pa. Then, high-frequency power was applied from the high-frequency power source 6 to the substrate holder 5 at 450W to generate plasma, which was used to clean the surface of the base 4 (to remove water and contaminants). Then, the argon gas was turned off, and the device was evacuated to 1 x 10 ^-3 Pa by a vacuum pump. Subsequently, toluene used to form a diamond-like carbon film was introduced into the showerhead 2 for introducing a source gas, and the pressure was adjusted to 5 Pa. Then, high-frequency power was applied from the high-frequency power source 6 to the substrate holder 5 at 450 W to generate plasma. A 100-nm diamond-like carbon film (DLC film) was formed on the surface of the base 4.

Under the same conditions as in this exemplary embodiment, a diamond-like carbon film for analysis evaluation was separately formed on the silicon base. According to the analysis, the diamond-like carbon film was composed of carbon and hydrogen of C:H = 75.3:24.7 based on atomic percent, and the hardness was 20 GPa.

The amount of dust in the wafer chuck was measured by the method described above. In the same manner as in this exemplary embodiment, a ceramic sintered body containing silicon carbide was subjected to oxidation treatment, and a diamond-like carbon film was formed on the ceramic sintered body to prepare a flat sheet sample of φ60. The flat sheet samples were inspected by the pin-on-disc method in the sliding test. After testing, the flat sheet samples were inspected for sliding wear marks and membrane separation by light microscopy and scanning electron microscopy. Table 1 shows the evaluation results.

Illustrative Example 2

A base made of polycrystalline silicon carbide formed by the CVD method ground into a specific shape was subjected to oxidation treatment in a heating furnace. The base was heated to 450°C in air at a heating rate of 5°C/min, held at 450°C for 10 hours, and then slowly cooled to room temperature over 12 hours. Subsequently, a base made of polycrystalline silicon carbide formed by the CVD method was placed in a high-frequency plasma CVD apparatus as shown in Fig. 1, which was evacuated to ^{1 x 10 -3 Pa by a vacuum pump.} Subsequently, argon gas for plasma cleaning was introduced into the showerhead 2 for introducing a source gas, and the pressure was adjusted to 5 Pa. Subsequently, high frequency power was applied from the high frequency power source 6 to the substrate holder 5 at 450 W to generate plasma, which was used to clean the surface of the base 4. Subsequently, toluene used to form a diamond-like carbon film was introduced into the showerhead 2 for introducing a source gas, and the pressure was adjusted to 5 Pa. Then, high-frequency power was applied from the high-frequency power source 6 to the substrate holder 5 at 600 W to generate plasma. A 150-nm diamond-like carbon film (DLC film) was formed on the surface of the base 4.

Under the same conditions as in this exemplary embodiment, a diamond-like carbon film for analysis evaluation was separately formed on the silicon base. According to the analysis, the diamond-like carbon film was composed of carbon and hydrogen of C:H = 80.5:19.5 based on atomic percent, and the hardness was 22 GPa.

The amount of dust in the wafer chuck was measured by the method described above. In the same manner as in this exemplary embodiment, a diamond-like carbon film was formed on a φ60 flat sheet sample made of CVD polycrystalline silicon carbide to prepare a sample. The flat sheet samples were inspected by the pin-on-disc method in the sliding test. After testing, the flat sheet samples were inspected for sliding wear marks and membrane separation by light microscopy and scanning electron microscopy. Table 1 shows the dust generation test and sliding evaluation results.

Illustrative Example 3

First, a base made of a ceramic sintered body containing ground silicon carbide of a specific shape was placed in a heating furnace, and an oxidation treatment was applied. The base was heated to 400°C in air at a heating rate of 10°C/min, held at 400°C for 5 hours, and then slowly cooled to room temperature over 8 hours. A base made of ceramic containing silicon carbide was placed in a high-frequency plasma CVD apparatus as shown in Fig. 1, which was evacuated to ^{1×10 −3 Pa by a vacuum pump.} Subsequently, argon gas for plasma cleaning was introduced into the showerhead 2 for introducing a source gas, and the pressure was adjusted to 5 Pa. Subsequently, high frequency power was applied from the high frequency power source 6 to the substrate holder 5 at 450 W to generate plasma, which was used to clean the surface of the base 4. In order to form an amorphous layer containing carbon, silicon, oxygen and hydrogen, a raw material gas hexamethyldisiloxane was introduced into the vacuum chamber 1 through a shower head 2 for introducing a raw material gas, and the pressure was adjusted to 5 Pa. Became. Then, high-frequency power was applied from the high-frequency power source 6 to the substrate holder 5 at 450 W to generate plasma. An 80-nm amorphous layer containing carbon, silicon, oxygen and hydrogen was formed on the surface of the base 4. Subsequently, the introduction of hexamethyldisiloxane was stopped. After the vacuum chamber 1 was evacuated to 1×10 ⁻³ Pa by a vacuum pump, toluene used to form a diamond-like carbon film was introduced into the showerhead 2 for introducing a source gas. The pressure was adjusted to 5 Pa. Then, high-frequency power was applied from the high-frequency power source 6 to the substrate holder 5 at 450 W to generate plasma. A 100-nm diamond-like carbon film (DLC film) was formed on the amorphous layer containing carbon, silicon, oxygen and hydrogen.

On the silicon base under the same conditions as in the present exemplary embodiment, an amorphous monolayer including carbon, silicon, oxygen and hydrogen, and a diamond-like carbon monolayer for analysis evaluation were separately formed. According to the analysis, the amorphous layer including carbon, silicon, oxygen and hydrogen has a composition of C:Si:O:H = 40.5:13.0:11.1:35.4 based on atomic percent. Further, according to the analysis, the diamond-like carbon film was composed of carbon and hydrogen of C:H = 75.3:24.7 based on atomic percent, and the hardness was 20 GPa.

The amount of dust in the wafer chuck was measured by the method described above. In the same manner as in this exemplary embodiment, a ceramic containing silicon carbide was oxidized, and an amorphous layer containing carbon, silicon, oxygen and hydrogen and a diamond-like carbon film were formed on the ceramic to prepare a flat sheet sample of φ60. I did. The flat sheet samples were inspected by the pin-on-disc method in the sliding test. After testing, the flat sheet samples were inspected for sliding wear marks and membrane separation by light microscopy and scanning electron microscopy. Table 1 shows the evaluation results.

Illustrative Example 4

A base consisting of a ceramic sintered body containing silicon carbide ground into a specific shape was placed in a heating furnace, heated to 600°C at a heating rate of 10°C/min in air for oxidation treatment, and 3 hours at 600°C. After holding for a period of time, it was slowly cooled to room temperature over 8 hours. Subsequently, a base made of a ceramic sintered body containing silicon carbide was placed in a high-frequency plasma CVD apparatus as shown in Fig. 1, which was evacuated to ^{1 x 10 -3 Pa by a vacuum pump.} In order to form an amorphous layer containing carbon, silicon, oxygen and hydrogen, the raw material gas hexamethyldisiloxane and argon gas are introduced into the vacuum chamber 1 in a ratio of 1:5 through the showerhead 2 for introducing the raw material gas. Was introduced and the pressure was adjusted to 6 Pa. Then, high-frequency power was applied from the high-frequency power source 6 to the substrate holder 5 at 600 W to generate plasma. A 50-nm amorphous layer containing carbon, silicon, oxygen and hydrogen was formed on the surface of the base 4. Subsequently, the introduction of hexamethyldisiloxane and argon gas was stopped. After the device was evacuated to 1 x 10 ^-3 Pa by a vacuum pump, toluene and argon gas used to form a diamond-like carbon film were introduced into the showerhead 2 for introducing a raw material gas in a ratio of 1:5, and the pressure Was adjusted to 4 Pa. Then, high-frequency power was applied from the high-frequency power source 6 to the substrate holder 5 at 650 W to generate plasma. A 100-nm diamond-like carbon film (DLC film) was formed on the amorphous layer containing carbon, silicon, oxygen and hydrogen.

On the silicon base under the same conditions as in the present exemplary embodiment, an amorphous layer containing carbon, silicon, oxygen and hydrogen and a diamond-like carbon film for analysis and evaluation were separately formed. According to the analysis, the amorphous layer containing carbon, silicon, oxygen and hydrogen has a composition of C:Si:O:H = 35.4:20.6:9.0:35.0 based on atomic percent. According to the analysis, the diamond-like carbon film was composed of carbon and hydrogen of C:H = 78.0:22.0 based on atomic percent, and the hardness was 21 GPa.

The amount of dust in the wafer chuck was measured by the method described above. In the same manner as in this exemplary embodiment, a ceramic containing silicon carbide was oxidized, and an amorphous layer containing carbon, silicon, oxygen and hydrogen and a diamond-like carbon film were formed on the ceramic to prepare a flat sheet sample of φ60. I did. The flat sheet samples were inspected by the pin-on-disc method in the sliding test. After testing, the flat sheet samples were inspected for sliding wear marks and membrane separation by light microscopy and scanning electron microscopy. Table 1 shows the evaluation results.

Comparative Example 1

In the same manner as in Exemplary Example 1, the base made of a ceramic sintered body containing silicon carbide ground into a specific shape was not subjected to oxidation, and an adhesive layer and a diamond-like carbon film were not formed on the base. The amount of dust in the base was determined by a specific method. A φ60 flat sheet sample of ceramic comprising silicon carbide was prepared without oxidation treatment and without the formation of an adhesive layer and a diamond-like carbon film. The samples were examined by the pin-on-disc method in the sliding test. After testing, the samples were inspected for sliding wear marks by light microscopy and scanning electron microscopy. Table 1 shows the evaluation results.

Comparative Example 2

In Comparative Example 2, a base made of a ceramic sintered body including silicon carbide ground in a specific shape in the same manner as in Exemplary Example 1 was heat treated in the same manner as in Exemplary Example 1 (400 °C). In this comparative example, the adhesive layer and the diamond-like carbon film (DLC film) were not formed. The amount of dust was measured by a specific method in the same manner as in Exemplary Example 1. A φ60 flat sheet sample of silicon carbide-based ceramics subjected to oxidation treatment only was prepared and examined by the pin-on-disk method in a sliding test. After testing, flat sheet samples of φ60 were inspected for sliding wear marks with an optical microscope and a scanning electron microscope. Table 1 shows the evaluation results.

evaluation

Exemplary Examples 1 to 4 of the present invention showed that the amount of dust was greatly reduced, no sliding wear marks were observed in the sliding test, the sliding durability was good, and the diamond-like carbon film was not separated. More specifically, in Exemplary Example 1 in which a diamond-like carbon film was formed on a wafer chuck made of a ceramic sintered base containing oxidized silicon carbide, the amount of dust was greatly reduced (1/100 of Comparative Example 1). . In the sliding test, the diamond-like carbon film was partially separated from the sintering aid portion, but no sliding wear marks were observed in the other portions. Thus, the slide test was substantially acceptable.

Exemplary Example 2 showed that the diamond-like carbon film on the polycrystalline silicon carbide member formed by the CVD method was not separated in the sliding test, and thus showed good adhesion. This is because the polycrystalline silicon carbide member formed by the CVD method without a sintering aid is more resistant to thermal oxidation treatment, and has higher adhesion to the diamond-like carbon film than the sintered body. In a wafer chuck comprising a base made of ceramic including silicon carbide sintering, the formation of an adhesive layer (Example Examples 3 and 4) further reduces dust generation and film separation.

Conversely, in Comparative Example 1 in which the chuck base was not oxidized and the adhesive layer and the diamond-like carbon film were not formed, the amount of dust was increased, and the sliding wear marks were observed in the sliding test, indicating poor sliding durability. In Comparative Example 2 in which only the oxidation treatment was performed, the amount of dust was greatly reduced, but the sliding wear marks were observed in the sliding test, indicating poor sliding durability.

Illustrative Examples 5 and 6

In the same manner as in Exemplary Example 1, a silicon film or a silicon nitride film was formed as an adhesive layer by a known sputtering method on a flat sheet sample of φ60 made of polycrystalline silicon carbide formed by the CVD method processed and oxidized. Under the same conditions as in Exemplary Example 3, a diamond-like carbon film was formed on the sample. For these samples, the load condition was changed to twice (100 g) in the sliding test by the pin-on-disc method. After testing, the samples were examined for sliding wear marks and membrane separation by light microscopy and scanning electron microscopy. According to the evaluation results, the two samples containing a silicon film or a silicon nitride film as an adhesive layer had no film separation and sliding wear marks.

Illustrative Example 7

An amorphous layer comprising carbon, silicon, oxygen, and hydrogen is on a flat sheet sample of φ60 made of polycrystalline silicon carbide formed by a CVD method processed and oxidized in the same manner as in Exemplary Example 1, as shown in FIG. It was formed as an adhesive layer by a high-frequency plasma CVD apparatus as shown. A diamond-like carbon film was formed on the sample under the same conditions as in Exemplary Example 1. For this sample, the load condition of the pin-on-disc method was changed to twice (100 g) in the sliding test. After testing, the samples were examined for sliding wear marks and membrane separation by light microscopy and scanning electron microscopy. According to the evaluation results, there were no membrane separation and sliding wear marks.

While the present invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the claims that follow is to be construed in the broadest sense so as to cover all such modifications and equivalent structures and functions.

Claims (13)

It is a wafer chuck comprising a base made of a ceramic containing silicon carbide,
The base is provided with an oxidation treatment layer, and a film made of diamond-like carbon (DLC) is formed on the outermost surface of the base. The method of claim 1,
A wafer chuck, wherein a layer comprising at least silicon or carbon is formed between the oxidized layer and the film. The method of claim 2,
The wafer chuck, wherein the layer containing at least silicon or carbon has a thickness of 0.01 μm or more and 1 μm or less. The method according to claim 2 or 3,
The wafer chuck, wherein the layer comprising at least silicon or carbon comprises silicon, silicon nitride, silicon carbide or carbon nitride. The method of claim 1,
A wafer chuck, wherein an amorphous layer comprising carbon, silicon, oxygen and hydrogen is formed between the oxidized layer and the film. The method of claim 5,
The amorphous layer comprising carbon, silicon, oxygen and hydrogen has a thickness of 0.01 μm or more and 1 μm or less. The method according to claim 5 or 6,
Each of the carbon atom concentration, silicon atom concentration, oxygen atom concentration, and hydrogen atom concentration of the amorphous layer containing carbon, silicon, oxygen and hydrogen is 5 atomic% or more, and the oxygen atom concentration is 20 atomic% or less. The method of claim 1,
The thickness of the film is 0.04 μm or more and 1 μm or less. The method of claim 1,
The oxidized layer has an oxygen atom concentration of more than 25 atomic%, the wafer chuck. It is a method of manufacturing a wafer chuck,
Oxidizing the surface of the base made of a ceramic containing silicon carbide, and
A method of manufacturing a wafer chuck comprising the step of forming a film made of diamond-like carbon (DLC). The method of claim 10,
After the step of oxidizing and before the step of forming the film, the method further comprises forming a layer containing at least silicon or carbon on the oxidized base. The method of claim 10,
After the oxidation treatment and before the film formation, the method of manufacturing a wafer chuck further comprises forming an amorphous layer including carbon, silicon, oxygen and hydrogen on the oxidized base. An exposure apparatus comprising the wafer chuck according to claim 1.

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