JP2021060573A - Wafer chuck, method for producing the same, and exposure apparatus - Google Patents

Abstract

To provide a wafer chuck that has reduced dusting and achieves improved durability by reduction in wear.SOLUTION: A wafer chuck includes a base, the base has an oxidation-treated layer, and a film made of diamond-like carbon (DLC) is formed on an outermost surface of the base.SELECTED DRAWING: Figure 1

Description

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

It is known that ceramic materials such as silicon carbide-based ceramics and silicon nitride-based ceramics are used as wafer chuck members used to support a substrate in a lithography process process for manufacturing a semiconductor device. Among them, silicon carbide-based ceramics are suitable as wafer chuck members because they have strong mechanical strength and thus are resistant to durability deterioration due to wear, and because they have high thermal conductivity, the positioning accuracy of semiconductor wafers is less likely to decrease due to temperature changes. However, when the silicon carbide member is ground and polished to be processed into a predetermined shape for use as a wafer chuck material, fine microcracks are generated on the surface of the silicon carbide member, and fine particles of silicon carbide ceramics are generated from that portion. It is known that it desorbs and becomes dust. When such dust is attached to the circuit portion of the semiconductor device, problems such as poor insulation of the circuit and short circuit occur.

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 generation from the wafer chuck (Patent Document 1).

Further, it is known that in silicon carbide ceramics used for motor parts and the like, the generation of dust is suppressed by performing a heat treatment at 400 to 1400 ° C. in an air or an oxidizing atmosphere (Patent Document 2). This is because when the heat treatment is performed in the air or an oxidizing atmosphere, a surface film containing an oxide is formed on the surface.

Japanese Unexamined Patent Publication No. 6-20324 JP-A-2002-47078

However, by forming a polycrystalline diamond film or a hard carbon film on the surface of the wafer chuck, dust generation can be suppressed only on the surface on which the film is formed, and from the side surface portion and the back surface portion on which the film is not formed. Dust generation could not be reduced.

Further, in silicon carbide ceramics, the generation of dust can be suppressed by performing a heat treatment at 400 to 1400 ° C. in the air or an oxidizing atmosphere. However, the surface coating containing the oxide produced at this time has a lower mechanical strength than the silicon carbide-based ceramics and also has a large coefficient of friction. In the case of motor parts, etc., this is not a major problem, but for members that require nanometer-order flatness, such as wafer chuck members, deterioration of durability as a wafer chuck due to deterioration of flatness due to wear and generation due to wear occur. Dust is a problem. Further, although the silicon carbide ceramic member has high wear resistance, wear occurs due to sliding with the wafer member for a long period of time, and deterioration of exposure performance such as positioning accuracy and resolution is observed.

The wafer chuck of the present invention is a wafer chuck having a base material made of ceramics containing silicon carbide, and the base material has an oxidation-treated layer and a film made of diamond-like carbon (DLC) is formed on the outermost surface. It is characterized by that.

The method for manufacturing a wafer chuck of the present invention is characterized by including a step of oxidizing the surface of a substrate with ceramics containing silicon carbide and a step of forming a film with diamond-like carbon (DLC).

The wafer chuck of the present invention suppresses dust generation and improves durability by reducing wear.

It is a schematic diagram of the film forming apparatus which concerns on this invention. It is a schematic diagram of the wafer chuck which concerns on this invention. It is a schematic diagram of the wafer chuck which concerns on this invention. It is a schematic diagram which shows the lithography process of the exposure apparatus which concerns on this invention.

Hereinafter, embodiments of the present invention will be specifically described.

A wafer chuck is a member that holds a semiconductor wafer in a lithography process apparatus for a semiconductor device. In the wafer chuck, protruding pin portions having a height and diameter of several tens of μm to several hundred μm are formed at intervals of several hundred μm to several mm on the contact surface with the semiconductor wafer, and for adsorbing the semiconductor wafer. Holes and grooves are also formed.

FIG. 2 is a schematic view of a wafer chuck used in the present invention. In the figure, (a) is a top view and (b) is a side view. 21 is a wafer chuck, and 22 is a suction hole used when sucking various wafers such as a silicon wafer (not shown) to the chuck, and penetrates in the thickness direction. In this drawing, a total of 27 wafers are shown side by side in the radial direction, but the size, number, and arrangement are appropriately adjusted so that the wafers are appropriately attracted and fixed to the chuck. Reference numeral 23 denotes a lift pin hole. When the lithography process for the wafer fixed to the chuck is completed, the wafer suction is stopped, the lift pin (not shown) rises from the back side of the chuck through the lift pin hole, and the wafer is pulled away from the chuck. Can be done. In this drawing, a total of three wafers are shown side by side in the circumferential direction, but the size, number, and arrangement are appropriately adjusted so that the wafer can be appropriately separated from the chuck. Reference numeral 24 denotes an upper surface of the wafer chuck, which holds a silicon wafer or the like. This portion is formed with the above-mentioned protruding pin portion (not shown). Reference numeral 25 denotes a brim portion of the wafer chuck, which can be fixed to the wafer stage.

FIG. 3 is a schematic view showing the structure of the diamond-like carbon film formed on the base material and the adhesion layer. A protruding pin portion 32 is formed on the base material 31. The shape of the pin portion in FIG. 3 is schematically shown, and the ratios such as height, width, and pin spacing are not correct. Correctly, as described above, the pin portions are generally formed in height and diameter of several tens of μm to several hundred μm and at intervals of several hundred μm to several mm. In the present invention, a film (diamond-like carbon film) 33 made of diamond-like carbon (DLC) is formed on the entire surface of the base material (upper surface, side surface, lower surface of the pin portion) as shown in FIG. 3 (b). Can be done. Further, in the present invention, as shown in FIG. 3C, the adhesion layer 34 and the diamond-like carbon film 33 can be formed in this order on the surface of the base material. That is, a diamond-like carbon (DLC) film is formed on the outermost surface of the wafer chuck.

FIG. 4 is a schematic view showing a lithography process in an exposure apparatus which is an example of an apparatus in which the wafer chuck of the present invention is mounted. In the figure, 41 is a light source for exposure, and a mercury lamp, a laser light source such as a KrF laser or an ArF laser, an X-ray light source, or the like can be used. Reference numeral 42 denotes a condenser lens, which can change the divergent light from the light source to parallel light. Reference numeral 43 denotes a mask in which a desired circuit pattern is drawn on the surface of a quartz member or the like on the wafer. 44 can reduce the circuit pattern drawn on the mask 43 with a reduction projection lens and project it on the wafer. Reference numeral 45 denotes a wafer made of silicon or the like, and a desired circuit pattern or the like is drawn on the photosensitive resist coated on the surface by a lithography process. Reference numeral 46 denotes a wafer chuck, which is installed on a wafer stage (not shown) and can hold a wafer such as silicon. The wafer and the wafer chuck can be sequentially moved by the wafer stage, and the circuit pattern can be repeatedly exposed on one wafer. In the schematic diagram of FIG. 4, an example is shown in which a circuit pattern is formed by a lithography process using a light source (light). However, the wafer chuck of the present invention can also be used in a process such as a nanoimprint process in which a fine pattern of several tens of nanometers or less is transferred by embossing a mold (die) as an original plate. ..

By mounting the wafer chuck of the present invention on an exposure apparatus, dust generation can be suppressed and durability can be improved by reducing wear.

The base material used for the wafer chuck of the present embodiment can be used by processing a ceramic material containing silicon carbide into a predetermined shape such as forming a pin shape on a contact surface with a semiconductor wafer.

The silicon carbide-containing ceramics used in the present embodiment are silicon carbide sintered bodies or polycrystalline bodies. In the case of a sintered body, in addition to the silicon carbide component, if a simple substance of Be (beryllium), B (boron), Al (aluminum) or a compound (carbide, nitride, oxide) is used as a sintering aid, it is dense. A good sintered body can be obtained. Further, the silicon carbide polycrystalline body can be formed by a chemical vapor deposition method (CVD method). Specifically, for example, a silicon carbide polycrystal is formed on a graphite substrate with a thickness of several mm by a thermal CVD method using silicon tetrachloride gas and methane gas as raw materials, and then the graphite substrate is removed by cutting or vaporizing at a high temperature. By doing so, a simple substance of the polycrystalline silicon carbide member can be obtained. Since the polycrystalline silicon carbide member formed by this CVD method does not contain a sintering aid, it has a higher purity than a sintered body, and has excellent adhesion when a diamond-like carbon film is formed. It is suitable as a wafer chuck member because of its high mechanical strength and thermal conductivity. In the present invention, it is referred to as a ceramic containing silicon carbide (or a silicon carbide-based ceramic) including a sintered body containing silicon carbide as a main component and a polycrystalline silicon carbide member formed by a CVD method.

The wafer chuck needs to have high flatness especially in the pin-shaped portion of the contact surface with the semiconductor wafer. The base material is processed into a predetermined shape by grinding and polishing, but at that time, fine microcracks are generated on the surface, and fine particles of ceramics containing silicon carbide are desorbed from that part to generate dust. It becomes. If such dust adheres to the circuit portion of the semiconductor device, it may cause poor insulation of the circuit, short circuit, or the like.

In the invention of the present embodiment, in order to solve this problem, first, the surface of the base material is oxidized with ceramics containing silicon carbide. Specifically, for example, heating is performed at a temperature of 300 ° C. to 700 ° C. for several tens of minutes to several tens of hours in an air atmosphere or an oxygen atmosphere. As a result, the microcracks on the surface are oxidized to form a film (oxidation-treated layer) containing an oxide. The thickness of the coating film (oxidation-treated layer) containing this oxide is about 1 nm to about 100 nm. The concentration of oxygen atoms contained in the oxide-containing coating film (oxidation-treated layer) is more than 25 atomic%. The concentration of oxygen atoms contained in this coating can be measured using an elemental analyzer of an electron microscope. Further, the composition of the coating film containing an oxide is the composition of carbon, silicon, and oxygen in the low temperature treatment, but the concentration of oxygen atoms tends to increase as the treatment temperature is raised and the time is lengthened.

Ceramic materials containing silicon carbide usually have high thermal stability and hardly oxidize at a temperature of about 300 ° C. to 700 ° C. However, it is considered that the microcracked portion generated by the grinding / polishing process becomes highly reactive due to defects and strains caused by the process, and is easily oxidized at a low temperature. It is considered that the formation of a film containing an oxide in the microcrack portion increases the volume of the crack surface portion and fills the crack portion to suppress the detachment of fine particles from the surface. Generally, the higher the oxidation treatment temperature, the thicker the film containing oxides and the higher the effect of preventing dust generation. However, if the temperature is 1000 ° C. or higher, thermal deformation occurs and the flatness required for the wafer chuck decreases. There is. Therefore, it is desirable to lower the oxidation treatment temperature from 300 ° C. to 700 ° C. and lengthen the treatment time (preferably several hours or more). In the case of a ceramic sintered body containing silicon carbide, the optimum oxidation treatment conditions differ depending on the particle size before sintering, the sintering state, the sintering aid, and other grinding / polishing conditions, so adjustments are made as appropriate. The optimum oxidation treatment conditions for the polycrystalline silicon carbide member formed by the CVD method also differ depending on the average particle size of the polycrystalline material and the grinding / polishing processing conditions, and thus are appropriately adjusted.

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

Usually, a diamond-like carbon film is a coating material having a large film stress and easily peeling off, but it is known that it has relatively good adhesion to a silicon carbide-based member.

However, in the case of a ceramic sintered body containing silicon carbide, an oxide layer is formed on the surface of the sintering aid depending on the oxidation treatment conditions. This may cause a problem that the adhesion between the diamond-shaped carbon film and the ceramic member containing silicon carbide is lowered and the diamond-shaped carbon film is easily peeled off. This is because the sintering aid material is more easily oxidized than the silicon carbide material. Therefore, it is desirable that the oxidation treatment temperature be as low as 300 ° C. to 700 ° C. in order to improve the adhesion of the diamond-like carbon film. Under these oxidation treatment conditions, the amount of sintering aid contained in the ceramic sintered body containing silicon carbide is generally as small as several weight% or less, so that the adhesion with the diamond-like carbon film is practically used. It is a possible level.

Further, since the polycrystalline silicon carbide member formed by the CVD method does not contain a sintering aid, there is no oxidation in the sintering aid portion, and the decrease in adhesion to the diamond-like carbon film due to the oxidation treatment is small. It is presumed that the oxidation of the cracked portion in the oxidation treatment is mainly a reaction inside the silicon carbide crystal particles, and that there is almost no oxidized portion on the surface portion in contact with the diamond-like carbon film. In this respect as well, the polycrystalline silicon carbide member formed by the CVD method is suitable as a base material.

Further, in order to improve the adhesion, a diamond-like carbon film can be laminated on the layer containing at least silicon or carbon after forming a layer containing at least silicon or carbon. That is, a layer containing at least silicon or carbon and a film made of diamond-like carbon (diamond-like carbon film) can be laminated in this order.

To further improve adhesion, an amorphous layer containing carbon, silicon, oxygen, and hydrogen is formed, and then an amorphous layer containing carbon, silicon, oxygen, and hydrogen is formed. It is also possible to laminate a diamond-like carbon film on top of it. That is, a layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen, and a diamond-like carbon film can be laminated in this order.

The above-mentioned layer containing at least silicon or carbon, or a layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen is called an adhesion layer, and is a silicon carbide-based ceramic member and a diamond-like carbon film. It is formed to further improve the adhesion.

The layer containing at least silicon or carbon in the present invention includes a silicon film, a silicon nitride film, a carbide film such as a silicon carbide film or a carbon nitride film, and the like. Further, oxygen may be contained, but the amount thereof is 25 atomic% or less, preferably 20 atomic% or less.

Further, the amorphous layer made of carbon, silicon, oxygen, and hydrogen is suitable as an adhesion layer because it has excellent adhesion to a diamond-like carbon film and has a small film stress. This film is preferably a film in which at least 5 atomic% or more of each of carbon, silicon, oxygen, and hydrogen atoms is present and the oxygen concentration is 20 atomic% or less. Each element contained in this film For analysis of the concentration of each element contained in this film, the elemental analyzer (energy dispersive X-ray analyzer) attached to the scanning electron microscope and X-ray photoelectron spectroscopy are used for carbon, silicon, and oxygen atoms. It can be done with a vessel (XPS). For light elements such as hydrogen atoms, concentration analysis can be performed with an elastic recoil detection analyzer (ERDA).

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

In FIG. 1, a vacuum pump and a vacuum valve (not shown) are installed in the vacuum chamber 1, and vacuum exhaust can be performed up to ^{1x10 -3 Pa.} The shower head / ground electrode 2 for introducing the raw material gas is provided with a large number of holes having a diameter of about 1 mm on the lower surface side in the drawing, and the raw material gas can be introduced from the holes. The diameter and pitch of the holes are appropriately adjusted to make the film thickness distribution of the film to be formed uniform. The shower head and ground electrode 2 for introducing the raw material gas is also used as the ground electrode. The raw material gas introduction line 3 is connected to a gas valve (not shown), a gas flow rate regulator, and a raw material gas cylinder.

When using this device to form a layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen, for example, a liquid organosilicon compound can be used as the raw material gas. The liquid organosilicon compound can be used by heating tetraethoxysilane, hexamethyldisiloxane, or the like (for example, about 40 ° C.) to gasify it. These gases can also be diluted with a rare gas (argon gas, helium gas, etc.), nitrogen gas, hydrogen gas, or the like.

As the raw material gas for the diamond-like carbon film, various carbon-containing gases and liquid organic compounds can be vaporized and used. As the carbon-containing gas, hydrocarbon gases such as methane, ethane, ethylene and acetylene, carbon monoxide, carbon halide and the like can be used. As the liquid organic compound, 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 can be used. These gases can also be diluted with a rare gas (argon gas, helium gas, etc.), nitrogen gas, hydrogen gas, or the like. The base material 4 is obtained by processing a base material made of ceramics containing silicon carbide into a predetermined shape and then subjecting it to the above-mentioned oxidation treatment. The substrate holder and high frequency introduction electrode 5 can be used as an electrode for applying a high frequency, on which a base material can be arranged. The high-frequency power supply 6 supplies high-frequency power to the substrate holder and high-frequency introduction electrode 5.

When forming a film containing at least silicon as the adhesion layer, for example, a silicon film can be formed by sputtering a silicon target by a known sputtering method. Further, a silicon nitride film can be formed by using a mixed gas of argon and nitrogen as the gas for sputtering. Further, a silicon carbide film can be formed by sputtering the silicon carbide target.

An amorphous layer used as an adhesion layer and composed of carbon, silicon, oxygen, and hydrogen is a film in which at least carbon atoms, silicon atoms, oxygen atoms, and hydrogen atoms each have a concentration of at least 5 atomic% or more. Is. Moreover, it is a film having an oxygen atom concentration of 20 atomic% or less, and is also called a C—Si—OH film. Further, as an unavoidable impurity mixed during film formation, a metal element derived from a chamber such as nitrogen, argon, iron or aluminum that can be used as a dilution gas and a substrate holder may be contained in an amount of about 1 atomic% or less. The amorphous layer containing carbon, silicon, oxygen, and hydrogen in the present embodiment is formed between the ceramic base material containing silicon carbide and the diamond-like carbon film as an intermediate layer for improving adhesion. used. Since this layer contains carbon and silicon, it has excellent adhesion, and since it contains hydrogen and oxygen, the film stress can be reduced, so that the adhesion is further improved. If the oxygen concentration is 20 atomic% or less, the adhesion is improved, but if it is more than 25 atomic%, the effect of improving the adhesion with the diamond-like carbon film may not be observed. Further, the amorphous layer containing carbon, silicon, oxygen, and hydrogen is preferably an amorphous film having no crystallinity.

The film thickness of the adhesion layer can be adjusted as appropriate, but is, for example, 0.01 μm or more and 1 μm or less, preferably 0.02 μm or more and 0.4 μm or less.

A diamond-like carbon (DLC) film (diamond-like carbon film) is basically amorphous, has high hardness, and is highly transparent in the infrared region, so it is called this way. .. The diamond-like carbon (DLC) film (diamond-like carbon film) may also be referred to as a hard carbon film, an i-C film (eye carbon film), a ta-C film (tetrahedral amorphous carbon film), or the like. Some of the compositions consist only of carbon atoms and unavoidable impurities, while others contain hydrogen gas derived from raw materials. The film containing hydrogen gas is sometimes referred to as an a-C: H film, but the diamond-like carbon film of the present invention also includes this a-C: H film. As unavoidable impurities, nitrogen, argon, oxygen in the atmosphere, or a metal element derived from a chamber such as iron or aluminum or a substrate holder may be contained in an amount of about 1 atomic% or less. The film thickness can be adjusted as appropriate, but is, for example, 0.04 μm or more and 1 μm or less, preferably 0.05 μm or more and 0.4 μm or less.

Next, the present invention will be described in detail based on examples.

(Evaluation of dust generation)
In this example, the amount of dust generated by the wafer chuck was evaluated by the following method. A base material made of ceramics containing silicon carbide ground into a predetermined shape is placed on a clean bench, and air in the vicinity is sucked and introduced into a particle counter to generate dust with a size of 0.1 μm or more. To measure. The amount of dust generated is based on the amount of dust generated in Comparative Example 1 in which the base material made of a ceramics sintered body containing silicon carbide is not oxidized and the adhesion layer and the diamond-like carbon film are not formed. This was done by comparing with the amount of dust generated in the comparative example.

(Evaluation of durability)
The durability was evaluated by a sliding test by the pin-on-disk method. A sample obtained by grinding a material equivalent to a ceramic base material containing silicon carbide into a flat plate shape and subjecting it to various treatments described in Examples and Comparative Examples was prepared. A test was carried out on the sample under a sliding condition of a width of 5 mm and a speed of 1 mm / sec while applying a load of 50 g of a Φ8 silicon sphere. After the test, observe whether there are sliding wear marks on the sliding part or whether there is film peeling in the case of a sample with a film with an optical microscope or scanning electron microscope, and further observe the wear mark shape with interferometry in which the surface shape can be observed. Measured with a meter.

(Example 1)
First, a base material made of a ceramics sintered body containing silicon carbide ground into a predetermined shape was placed in a heating furnace and subjected to an oxidation treatment. As for the heating conditions, the temperature was raised to 400 ° C. at a heating rate of 10 ° C./min under an atmospheric atmosphere, kept at 400 ° C. for 5 hours, and then slowly cooled to room temperature over 8 hours. Next, the base material made of a ceramic sintered body containing silicon carbide was placed in a high-frequency plasma CVD apparatus as shown in FIG. 1, and vacuum exhausted to 1 ^{x 10 -3 Pa by a vacuum pump.} Next, argon gas was introduced into the shower head 2 for introducing the raw material gas for plasma cleaning, and the pressure was adjusted to 5 Pa. Then, 450 W of high frequency was applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and the surface of the base material 4 was cleaned (removal of moisture and dirt). After that, the introduction of argon gas was stopped, and vacuum exhaust was performed ^{to 1 x 10 -3 Pa by a vacuum pump.} Next, toluene was introduced into the shower head 2 for introducing the raw material gas for forming the diamond-like carbon film, and the pressure was adjusted to 5 Pa. Then, 450 W of high frequency was applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and a diamond-like carbon film (DLC film) of 100 nm was formed on the surface of the base material 4.

Separately, a diamond-like carbon film was formed on the silicon substrate under the same conditions as in the present embodiment for analysis and evaluation. As a result of the analysis, the diamond-like carbon film was composed of carbon and hydrogen, the composition of which was C: H = 75.3: 24.7 atom%, and the hardness was 20 GPa.

This wafer chuck was evaluated by measuring the amount of dust generated by the above-mentioned predetermined method. Further, a φ60 flat plate sample of a ceramics sintered body containing silicon carbide was prepared by performing an oxidation treatment and forming a diamond-like carbon film by the same method as in the present example. The prepared flat plate sample was subjected to a sliding test by the pin-on disk method described above, and after the test, it was observed with an optical microscope and a scanning electron microscope whether there were any sliding wear marks or film peeling. The evaluation results are shown in Table 1.

(Example 2)
A substrate made of polycrystalline silicon carbide formed by a CVD method ground into a predetermined shape was placed in a heating furnace and subjected to an oxidation treatment. As for the heating conditions, the temperature was raised to 450 ° C. at a heating rate of 5 ° C./min under an atmospheric atmosphere, kept at 450 ° C. for 10 hours, and then slowly cooled to room temperature over 12 hours. Next, the polycrystalline silicon carbide base material formed by this CVD method was placed in a high-frequency plasma CVD apparatus as shown in FIG. 1, and vacuum exhausted to 1 ^{x 10 -3 Pa by a vacuum pump.} Next, argon gas was introduced into the shower head 2 for introducing the raw material gas for plasma cleaning, and the pressure was adjusted to 5 Pa. Then, 450 W of high frequency was applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and the surface of the base material 4 was cleaned. Next, toluene was introduced into the shower head 2 for introducing the raw material gas for forming the diamond-like carbon film, and the pressure was adjusted to 5 Pa. Then, 600 W of high frequency was applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and a diamond-like carbon film (DLC film) of 150 nm was formed on the surface of the base material.

Separately, a diamond-like carbon film was formed on the silicon substrate under the same conditions as in the present embodiment for analysis and evaluation. As a result of the analysis, the diamond-like carbon film was composed of carbon and hydrogen, the composition of which was C: H = 80.5: 19.5 atom%, and the hardness was 22 GPa.

This wafer chuck was evaluated by measuring the amount of dust generated by the above-mentioned predetermined method. Further, by the same method as in this example, a sample having a diamond-like carbon film formed on the φ60 flat plate sample made of CVD polycrystalline silicon carbide was prepared. The prepared flat plate sample was subjected to a sliding test by the pin-on disk method described above, and after the test, sliding wear marks and film peeling were observed with an optical microscope and a scanning electron microscope. Table 1 shows the results of the dust generation test and sliding evaluation.

(Example 3)
First, a base material made of a ceramics sintered body containing silicon carbide ground into a predetermined shape was placed in a heating furnace and subjected to an oxidation treatment. As for the heating conditions, the temperature was raised to 400 ° C. at a heating rate of 10 ° C./min under an atmospheric atmosphere, kept at 400 ° C. for 5 hours, and then slowly cooled to room temperature over 8 hours. Next, the ceramic substrate containing silicon carbide was placed in a high-frequency plasma CVD apparatus as shown in FIG. 1, and vacuum exhausted to 1 ^{x 10 -3 Pa by a vacuum pump.} Next, argon gas was introduced into the shower head 2 for introducing the raw material gas for plasma cleaning, and the pressure was adjusted to 5 Pa. Then, 450 W of high frequency was applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and the surface of the base material 4 was cleaned. Next, in order to form a layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen, hexamethyldisiloxane as a raw material gas is introduced into the raw material gas introduction shower head 2 in a vacuum chamber, and the pressure is 5 Pa. Adjusted to be. Then, 450 W of high frequency was applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and an amorphous layer containing carbon, silicon, oxygen, and hydrogen was formed at 80 nm on the surface of the base material 4. Next, the introduction of hexamethyldisiloxane was stopped. ^{Then, after vacuum exhausting to 1 x 10 -3} Pa with a vacuum pump, toluene was introduced into the raw material gas introduction shower head 2 for forming a diamond-like carbon film. Then, the pressure was adjusted to 5 Pa. After that, a high frequency of 450 W is applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and a diamond-like carbon film (DLC film) is formed on the surface of a layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen. Was formed at 100 nm.

Separately, for analysis and evaluation, each single layer of a layer containing carbon, silicon, oxygen, and hydrogen and a diamond-like carbon film, which is amorphous, is placed on a silicon substrate under the same conditions as in the above embodiment. Formed. As a result of the analysis, the composition of the layer which is amorphous and contains carbon, silicon, oxygen, and hydrogen is C: Si: O: H = 40.5: 13.0: 11.1: 35. It was 4 amorphous. The diamond-like carbon film was composed of carbon and hydrogen, the composition of which was C: H = 75.3: 24.7 atom%, and the hardness was 20 GPa.

This wafer chuck was evaluated by measuring the amount of dust generated by the above-mentioned predetermined method. Further, φ60 of a ceramic containing silicon carbide, which is oxidized and amorphous by the same method as in the present embodiment and has a layer containing carbon, silicon, oxygen, and hydrogen and a diamond-like carbon film formed. A flat plate sample was prepared. The prepared flat plate sample was subjected to a sliding test by the pin-on disk method described above, and after the test, it was observed with an optical microscope and a scanning electron microscope whether there were any sliding wear marks or film peeling. The evaluation results are shown in Table 1.

(Example 4)
A base material made of a ceramics sintered body containing silicon carbide ground into a predetermined shape is placed in a heating furnace, and the oxidation treatment is carried out in an atmospheric atmosphere at a heating rate of 10 ° C./min to 600 ° C. , 600 ° C. for 3 hours, and then slowly cooled to room temperature for 8 hours. Next, the base material made of a ceramic sintered body containing silicon carbide was placed in a high-frequency plasma CVD apparatus as shown in FIG. 1, and vacuum exhausted to 1 ^{x 10 -3 Pa by a vacuum pump.} Next, in order to form a layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen, hexamethyldisiloxane and argon gas are used as raw material gases in a vacuum chamber at a ratio of 1: 5 to introduce the raw material gas. It was introduced into 2 and the pressure was adjusted to 6 Pa. Then, 600 W of high frequency was applied from the high frequency power source 6 to the substrate holder 5 to generate plasma, and a layer which was amorphous and contained carbon, silicon, oxygen, and hydrogen was formed at 50 nm on the surface of the base material 4. Next, the introduction of hexamethyldisiloxane was stopped, and vacuum exhaust was performed ^{to 1x10 -3 Pa by a vacuum pump.} Then, toluene and argon gas were introduced into the raw material gas introduction shower head 2 at a ratio of 1: 5 for forming a diamond-like carbon film, and the pressure was adjusted to 4 Pa. After that, 650 W of high frequency is applied from the high frequency power supply 6 to the substrate holder 5 to generate plasma, and a diamond-like carbon film (DLC film) is formed on the surface of a layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen. Was formed at 100 nm.

Separately, a single layer of a layer containing carbon, silicon, oxygen, and hydrogen and a diamond-like carbon film, which is amorphous for analysis and evaluation, is formed on the silicon substrate under the same conditions as in this embodiment. did. As a result of the analysis, the composition of the layer which is amorphous and contains carbon, silicon, oxygen, and hydrogen is C: Si: O: H = 35.4: 20.6: 9.0: 35. It was 0 atom%. The diamond-like carbon film was composed of carbon and hydrogen, the composition of which was C: H = 78.0: 22.0 atom%, and the hardness was 21 GPa.

Further, this wafer chuck was evaluated by measuring the amount of dust generated by the above-mentioned predetermined method. Further, φ60 of a ceramic containing silicon carbide, which is oxidized and amorphous by the same method as in the present embodiment and has a layer containing carbon, silicon, oxygen, and hydrogen and a diamond-like carbon film formed. A flat plate sample was prepared. The prepared flat plate sample was subjected to a sliding test by the pin-on disk method described above, and after the test, it was observed with an optical microscope and a scanning electron microscope whether there were any sliding wear marks or film peeling. The evaluation results are shown in Table 1.

(Comparative Example 1)
The base material made of a ceramics sintered body containing silicon carbide ground into a predetermined shape in the same manner as in Example 1 is not subjected to an oxidation treatment, and is further described above without forming an adhesion layer and a diamond-like carbon film. The amount of dust generated was measured and evaluated by the predetermined method of. Further, a φ60 flat plate sample of ceramics containing silicon carbide, which was not subjected to the oxidation treatment and was not further formed with the adhesion layer and the diamond-like carbon film, was prepared. This sample was subjected to a sliding test by the pin-on disk method described above, and the sliding wear marks after the test were observed with an optical microscope and a scanning electron microscope. The evaluation results are shown in Table 1.

(Comparative Example 2)
In Comparative Example 2, a base material made of a ceramics sintered body containing silicon carbide ground into a predetermined shape in the same manner as in Example 1 was subjected to the same heat treatment (380 ° C.) as in Example 1. In this comparative example, the amount of dust generated was measured and evaluated by the same predetermined method as in Example 1 without forming the adhesion layer and the diamond-like carbon film (DLC film). In addition, a φ60 flat plate sample of silicon carbide-based ceramics that was only oxidized was prepared, and this sample was subjected to a sliding test by the pin-on disk method described above, and the sliding wear marks after the test were detected by an optical microscope and scanning electrons. It was observed with a microscope. The evaluation results are shown in Table 1.

(Evaluation)
In Examples 1 to 3 of the present invention, the amount of dust generated is significantly reduced, the sliding durability is good such that no sliding wear marks are observed in the sliding test, and the diamond-like carbon film is peeled off. I found that I couldn't. That is, in Example 1 in which a diamond-like carbon film was formed on a wafer chuck of a ceramics sintered base material containing oxidized silicon carbide, the amount of dust generated was significantly reduced (1/100 as compared with Comparative Example 1). did. Further, in the sliding test, the diamond-like carbon film was partially peeled off at the sintering aid portion, but no sliding wear marks were observed in the other portions, which was at a level where there was no problem in practical use.

Further, when a polycrystalline silicon carbide member formed by the CVD method is used as shown in Example 2, the diamond-like carbon film has good adhesion without film peeling in the slidability evaluation. It turned out. This is because the polycrystalline silicon carbide member formed by the CVD method is more stable to the oxidation treatment by heating because it does not contain a sintering aid as compared with the sintered body, and forms a diamond-like carbon film. This is because it has excellent adhesion. Further, in the case of a wafer chuck using a base material obtained by sintering ceramics containing silicon carbide, it was found that the formation of an adhesive layer (Examples 3 and 4) further suppresses the generation of dust and film peeling. ..

On the other hand, in Comparative Example 1 in which the chuck base material was not oxidized and the adhesion layer and the diamond-like carbon film were not formed, the amount of dust generated was high and the sliding wear marks were observed in the sliding test. It was found that the sliding durability was poor, such as being seen. Further, it was found that when only the oxidation treatment of Comparative Example 2 was performed, the amount of dust generated was significantly reduced, but the sliding durability was lowered such that sliding wear marks were observed in the sliding test.

(Examples 5 and 6)
CVD method that was processed and oxidized in the same manner as in Example 1 A silicon film and a silicon nitride film were formed as adhesion layers on a Φ60 flat plate sample made of polycrystalline silicon carbide by a known sputtering method. Further, a diamond-like carbon film was formed on this sample under the same conditions as in Example 3. For this sample, the load condition of the sliding test by the pin-on disk method described above was changed to 2 times (100 g), and after the test, it was observed with an optical microscope and a scanning electron microscope whether there were any sliding wear marks or film peeling. did. As a result of the evaluation, no film peeling or sliding wear marks were observed in both samples using the silicon film and the silicon nitride film as the adhesion layer.

(Example 7)
A Φ60 flat plate sample made of polycrystalline silicon carbide processed and oxidized in the same manner as in Example 1 using a high-frequency plasma CVD apparatus as shown in FIG. 1, which is amorphous as an adhesion layer and is carbon. , Silicon, oxygen, and hydrogen were formed. Further, a diamond-like carbon film was formed on this sample under the same conditions as in Example 1. For this sample, the load condition of the sliding test by the pin-on disk method described above was changed to 2 times (100 g), and after the test, it was observed with an optical microscope and a scanning electron microscope whether there were any sliding wear marks or film peeling. did. As a result of the evaluation, it was confirmed that no film peeling or sliding wear marks were observed.

1 Vacuum chamber 2 Shower head and ground electrode for raw material gas introduction 3 Raw material gas introduction line 4 Base material 5 Substrate holder and high frequency introduction electrode 6 High frequency power supply 21 Wafer chuck 22 Suction hole 23 Lift pin hole 24 Wafer chucking part 25 Brim 31 Material 32 Pin part 33 Diamond-like carbon film 34 Adhesive layer 41 Light source 42 Condenser lens 43 Mask 44 Reduction projection lens 45 Wafer 46 Wafer chuck

Claims (13)

A wafer chuck having a base material made of ceramics containing silicon carbide.
A wafer chuck characterized in that the base material has an oxidation-treated layer and a film made of diamond-like carbon (DLC) is formed on the outermost surface. The wafer chuck according to claim 1, wherein a layer containing at least silicon or carbon is formed between the oxidation-treated layer and the film. The wafer chuck according to claim 2, wherein the thickness of the layer containing at least silicon or carbon is 0.01 μm or more and 1 μm or less. The wafer chuck according to claim 2 or 3, wherein the layer containing at least silicon or carbon is a layer containing silicon, silicon nitride, silicon carbide, or carbon nitride as a main component. The wafer chuck according to claim 1, wherein a layer which is amorphous and contains carbon, silicon, oxygen, and hydrogen is formed between the oxidation-treated layer and the film. The wafer chuck according to claim 5, wherein the layer that is amorphous and contains carbon, silicon, oxygen, and hydrogen has a thickness of 0.01 μm or more and 1 μm or less. The amorphous layer containing carbon, silicon, oxygen, and hydrogen has a carbon atom, a silicon atom, an oxygen atom, and a hydrogen atom having a concentration of 5 atomic% or more, and an oxygen atom concentration of 5 atomic% or more. The wafer chuck according to claim 5 or 6, wherein the content is 20 atomic% or less. The wafer chuck according to any one of claims 1 to 7, wherein the thickness of the film is 0.04 μm or more and 1 μm or less. The wafer chuck according to any one of claims 1 to 8, wherein the oxidation-treated layer has an oxygen concentration of more than 25 atomic%. The process of oxidizing the surface of the substrate with ceramics containing silicon carbide,
A method for manufacturing a wafer chuck, which comprises a step of forming a film made of diamond-like carbon (DLC). After the step of oxidizing treatment and before the step of forming the film,
The method for manufacturing a wafer chuck according to claim 10, further comprising a step of providing a layer containing at least silicon or carbon on the oxidized substrate. After the step of oxidizing treatment and before the step of forming the film,
The method for manufacturing a wafer chuck according to claim 10, further comprising a step of providing a layer which is amorphous and contains carbon, silicon, oxygen, and hydrogen on the oxidation-treated substrate. An exposure apparatus equipped with the wafer chuck according to any one of claims 1 to 9.

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