WO2005055313A1

WO2005055313A1 - Electrostatic chuck, exposure apparatus, and object chucking method

Info

Publication number: WO2005055313A1
Application number: PCT/JP2004/017781
Authority: WO
Inventors: Keiichi Tanaka; Kazunori Saitou; Shunichi Sasaki; Kazuho Nakanishi; Hiroshi Suzuki; Hironori Ishida; Mamoru Ishii; Tatsuya Shiogai
Original assignee: Nikon Corporation; Nihon Ceratec Corporation; Taiheiyo Cement Corporation
Priority date: 2003-12-01
Filing date: 2004-11-30
Publication date: 2005-06-16
Also published as: JP2005191515A

Abstract

An electrostatic chuck (10) has a structure where independently drivable electrodes (12a, 12b) are provided in a dielectric ceramic body (11). The electrostatic chuck (10) is fixed at its side surface inside a semiconductor manufacturing apparatus, and the lower surface of the electrostatic chuck (10) chucks and holds an object. The lower surface of the dielectric ceramic body (11) for chucking and holding the object is concave. With this, when, for example, a plate-shaped glass mask is held, the warp of the glass mask is corrected to enhance the planarity of the glass mask.

Description

Specification

Electrostatic chuck, exposure apparatus, and method of adsorbing an object

Technical field

The present invention relates to an electrostatic chuck or the like provided in a semiconductor manufacturing apparatus, and more particularly, to an electrostatic chuck that sucks and holds an object to be sucked such as a mask on the lower surface thereof, and to such an electrostatic chuck. The present invention relates to an exposure apparatus provided with a chuck and a method for attracting an object to be attracted to an electrostatic chuck. Background art

[0002] In semiconductor manufacturing technology, the speeding up and large capacity of semiconductor devices largely depend on the progress of miniaturization technology. Among the miniaturization technologies, in particular, the advance of the lithography technology for forming patterns plays a central role. Recently, higher integration of semiconductor devices is required, and it is difficult to use conventional KrF excimer laser or ArF excimer laser lithography technology under the design rule of less than 100 nm. Therefore, as a lithography technology that can respond to such a design rule, EUV using extreme ultraviolet (Extreme UV (EU V)), which has the same image forming principle as conventional optical lithography and has a wavelength shorter than one digit, is used. Lithography technology has been proposed. In such EUV lithography technology, a method of fixing the mask so that the mask can be irradiated with light from below and reflected can be considered.

[0003] However, in EUV lithography technology, the shorter the wavelength of the light source, the flatness of the reflective surface of the mask is directly related to the exposure accuracy. For example, a method of mechanically holding or supporting the periphery of the mask cannot be used. This is because, in the method of holding or supporting the periphery of the mask, the mask is curved or warped, and the flatness of the reflection surface of the mask is reduced, thereby lowering the exposure accuracy.

[0004] Therefore, as a method of fixing the mask, a method of using an electrostatic chuck used for holding a silicon wafer as an object to be processed in a vacuum atmosphere in semiconductor manufacturing technology is considered. The conventional electrostatic chuck has a structure in which the silicon wafer is sucked and held from below so that the processing surface of the silicon wafer faces upward (for example, see Patent Document 1). Therefore, when the conventional electrostatic chuck is used upside down, the flatness of the mask cannot be maintained high due to the radius due to the weight of the mask, and the radius due to the weight of the electrostatic chuck cannot be maintained. Also, the flatness of the mask may be reduced.

[0005] Hereinafter, prior art documents related to the present invention are listed.

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-168384

Disclosure of the invention

Problems to be solved by the invention

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electrostatic chuck capable of suction-holding an object to be sucked with high accuracy on a bottom surface. Another object of the present invention is to provide an exposure apparatus having such an electrostatic chuck. It is still another object of the present invention to provide a method of adsorbing an object to be held by an electrostatic chuck with high accuracy.

Means for solving the problem

[0007] In one form of the electrostatic chuck of the present invention, a suction surface for sucking and holding an object to be sucked is formed on a lower surface, and the suction surface is formed in a concave shape. Thus, when the object to be adsorbed is held by suction on its lower surface, the shape accuracy of the object to be sucked and held by suction can be enhanced. For example, if the object to be sucked is a substrate such as a mask, the flatness thereof can be maintained well, and the exposure accuracy can be improved.

[0008] In another form of the electrostatic chuck of the present invention, the suction surface is formed directly on the lower surface of the dielectric. Thereby, the attraction force can be increased.

In another embodiment of the electrostatic chuck according to the present invention, the side surface is fixed inside the semiconductor manufacturing apparatus. Thereby, the electrostatic chuck can be reliably supported.

In another form of the electrostatic chuck of the present invention, the dielectric has a volume resistivity of 1 × 10 ⁹ —1 × 10 ″ Ω′cm, a Young's modulus of lOOGPa or more, and 20 ° C.—26 °. average thermal bulging expansion coefficient of C is 0. 5 X 10- ⁶ -. are 0. 5 X 10- ⁶ which by connexion desired suction force can be obtained, an electrostatic due to changes in the usage environment of the electrostatic chuck The deformation of the chuck is suppressed.

[0009] In another form of the electrostatic chuck of the present invention, the object to be attracted is plate-like glass having a Young's modulus of less than 100 GPa, and is attracted and held on the attracting surface with high precision. According to another embodiment of the electrostatic chuck of the present invention, there are provided two or more independently-driveable electrodes arranged substantially concentrically, which generate an electrostatic force for adsorbing and holding an object to be adsorbed on a dielectric. ing. Therefore, after the substantially central portion of the adsorption surface of the object to be adsorbed is suction-held at the center of the lower surface, the non-adsorption portion of the adsorption surface of the object to be adsorbed can be adsorbed and held outside the center of the lower surface. Thus, the shape accuracy of the object to be adsorbed can be maintained at a high level, and the occurrence of displacement of the object to be adsorbed when the object to be adsorbed is held by adsorption can be suppressed.

[0010] In one embodiment of the exposure apparatus of the present invention, since the electrostatic chuck of the present invention is provided, high-precision exposure processing is possible.

In one embodiment of the method for adsorbing an object to be adsorbed according to the present invention, the object to be adsorbed is brought into contact with an electrostatic chuck having a concave lower surface and a concave suction surface on the lower surface. Then, the object is adsorbed and held on the adsorption surface. Then, after the substantially central portion of the object to be sucked is suction-held at the center of the suction surface, the non-sucked portion of the object to be sucked is held outside the center of the suction surface. In such a method for adsorbing an object to be adsorbed, when the object to be adsorbed is a plate-like glass held in a substantially horizontal posture by supporting the peripheral portion thereof, the flatness of the object is favorably maintained. Can be.

The invention's effect

According to the present invention, when an object to be adsorbed is suction-held on its bottom surface, the shape accuracy when the object to be adsorbed is being suction-held can be improved. For example, if the object to be adsorbed is a substrate such as a mask, its flatness can be maintained well, thereby increasing the exposure accuracy.

Brief Description of Drawings

FIG. 1 is a schematic sectional view of an electrostatic chuck according to the present invention.

FIG. 2 is a plan view of the electrostatic chuck shown in FIG. 1, and an explanatory diagram showing a shape of a vertical cross section including a line A and a line B shown in the plan view.

FIG. 3 is an explanatory view showing electrode shapes of the electrostatic chuck shown in FIG. 1.

FIG. 4 is a schematic bottom view of another electrostatic chuck according to the present invention, which also looks at a force on a suction surface.

FIG. 5 is a schematic diagram showing a schematic configuration of an EUV optical lithography system according to the present invention.

FIG. 6 is an explanatory view showing a restrained position of the electrostatic chuck. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, a description will be given of an electrostatic chuck for attracting and holding a mask provided in an EUV exposure apparatus. FIG. 1 is a schematic sectional view (vertical sectional view) of the electrostatic chuck 10. The electrostatic chuck 10 has a structure in which electrodes 12a and 12b are embedded in a plate-shaped dielectric ceramic body 11.

The electrostatic chuck 10 suction-holds the mask 20 as a processing target on the bottom surface (lower surface) of the electrostatic chuck 10, that is, the bottom surface (lower surface) of the dielectric ceramic body 11. In the following description, the bottom surface (lower surface) of the electrostatic chuck 10 will be referred to as the “suction surface”.

FIG. 2 is a plan view of the electrostatic chuck 10 (FIG. 2 (a)) and an explanatory diagram showing the shape of a vertical cross section (plane including the Z axis) including lines A and B shown in the plan view ( Figures 2 (b) and 2 (c)). As shown in FIGS. 1 and 2, the suction surface of the electrostatic chuck 10 that holds the mask 20 by suction is concave. In other words, the upper surface of the dielectric ceramic body 11 is flat, and the bottom surface (lower surface) of the dielectric ceramic body 11 is such that the thickness of the substantially central portion of the dielectric ceramic body 11 is smaller than the thickness of its peripheral portion (this gap is reduced). 2 (b) and 2 (c). 1 and 2, the concave form of the suction surface of the electrostatic chuck 10 is exaggerated for understanding the invention.

[0015] The reason why the suction surface of the electrostatic chuck 10 is concave is as follows. Generally, the mask 20 is made of glass, and a pattern is formed on one side thereof. In order to form this pattern with high precision, the glass substrate for the mask 20 has high parallelism (thickness uniformity) and flatness. When a mask 20 manufactured using such a glass substrate is held by an electrostatic chuck of a type that sucks and holds the bottom surface of the mask, the mask 20 has its own weight due to its own weight radius and the radius of the electrostatic chuck itself. The flatness of the pattern and the pattern accuracy deteriorates.

[0016] Therefore, it is necessary to provide the electrostatic chuck with a function of correcting the radius of the mask 20. The step of holding the mask 20 on the electrostatic chuck 10 will be described in detail later. However, like the electrostatic chuck 10, the bottom surface of the dielectric ceramic body 11 is previously processed into a concave shape in accordance with the radius of the mask 20. In this way, the mask 20 exhibits a high flatness while being held by the electrostatic chuck 10. [0017] As a method of making the bottom surface of the dielectric ceramic body 11 such a concave shape, the mask 20 is actually adsorbed during processing and its flatness is measured, and the calorie is adjusted so that a desired flatness is obtained. There is a way to continue. Also, by calculating the radius shapes from the material properties of the mask 20 and the dielectric ceramic body 11 and the like, based on the calculated values, a certain shape of the dielectric ceramic body 11 is obtained. This is preferable because the processing time can be reduced.

Generally, the Young's modulus of the glass used for the mask 20 for EUV exposure is less than 100 GPa. The dielectric ceramic body 11 is required to have rigidity that does not bend due to the rigidity of the mask 20 when the mask 20 having such Young's modulus is sucked and held. Also, the electrostatic chuck 10 has a force fixed to the inside of the EUV exposure apparatus through its side surface. At this time, a certain stress is applied to the dielectric ceramic body 11, so that the dielectric ceramic body 11 Rigidity that is not deformed by stress is required. For this reason, a material having a Young's modulus of 100 GPa or more is suitably used as the dielectric ceramic body 11.

In order to fix the electrostatic chuck 10 in the EUV exposure apparatus, a rod-shaped or plate-shaped jig is attached to the side surface of the dielectric ceramic body 11, and these jigs are attached to the frame of the EUV exposure apparatus. Examples thereof include a method of fixing the dielectric ceramic body 11 to a movable stage and the like, and a method of holding the dielectric ceramic body 11 by applying pressing forces from a plurality of predetermined directions, but are not limited thereto. Further, the thickness of the dielectric ceramic body 11 is determined in consideration of a method of fixing the electrostatic chuck 10, a space for installation, and the like, but is preferably thick from the viewpoint of preventing the occurrence of a radius. No.

[0020] The dielectric ceramic body 11 has a volume at the operating temperature of the electrostatic chuck 10 so that the electrostatic chuck 10 can use the Johnsen-Rahbek force as a mechanism of an attraction force for adsorbing an object to be attracted. A material with a resistivity of 1 X 10 ⁹ Ω'cm—1 X 10 ¹⁴ Ω'cm is preferably used

When a mask is held in an EUV exposure apparatus, the electrostatic chuck 10 attracts and holds one mask for a long time, so that electric charges easily accumulate in the dielectric ceramic body 11. For this reason, if a high-resistance material exceeding 1 X 10 "Ω'cm is used for the dielectric ceramics 11, the mask will not be quickly detached from the electrostatic chuck 10 when the mask is replaced. By using a material with a volume resistivity of 1 X 10 ⁹ Ω · cm—1 X 10 "Ω · cm for the body 11 The occurrence of such a problem is prevented.

When EUV exposure is performed by holding the mask 20 by suction on the electrostatic chuck 10, the mask 20 generates heat with little force due to EUV. When the mask 20 expands due to this heat generation, the dimensional accuracy of the pattern formed on the mask 20 deteriorates. Therefore, a glass material of zero expansion is used for the glass substrate for the mask 20. On the other hand, when the mask 20 generates heat, the heat is transmitted to the electrostatic chuck 10 holding and holding the mask, whereby the dielectric ceramic body 11 is thermally expanded and deformed. The deformation due to the thermal expansion of the dielectric ceramic body 11 causes a displacement of the mask 20 and a decrease in flatness.

[0022] Therefore, it is preferable instrument specifically using thermal expansion coefficient is small material as a dielectric ceramic body 11, an average thermal expansion coefficient at 20 ° C- 26 ° C gar 0. 5 X 10- ⁶ — It is preferred to use a material that is 0.5 x 10 — ⁶ .

The characteristics required for the dielectric ceramic body 11 described above, that is, the volume resistivity is 1 × 10 ⁹ -IX 10 ¹⁴ Ω'cm, the Young's modulus is lOOGPa or more, and the average heat at 20 ° C. to 26 ° C. expansion coefficient gar 0. 5 X 10 ^"6 -0. the ceramic material is 5 X 10- ^6, double coupling material of the ceramic material with ceramic material and a negative thermal expansion coefficient having a positive thermal expansion coefficient No.

Examples of the ceramic material having a positive coefficient of thermal expansion include silicon carbide (SiC), silicon nitride (SiN), alumina (Al 2 O 3), and zirconia (ZrO 2), and have a negative coefficient of thermal expansion.

2 3 2

Examples of the ceramic material include eucryptite-cordierite. Therefore, when baking is difficult if these materials are blended in a predetermined ratio, a sintering aid may be added in a range where a predetermined coefficient of thermal expansion can be obtained.

FIG. 3 is an explanatory view showing the planar shape of the electrodes 12a and 12b of the electrostatic chuck 10.

The electrodes 12a and 12b are arranged near the bottom surface of the dielectric ceramic body 11 so that the suction surface of the electrostatic chuck 10 is the bottom surface.

The electrode 12a is provided substantially at the center of the dielectric ceramic body 11, and the electrode 12b is provided outside the electrode 12a and insulated from the electrode 12a. In the electrostatic chuck 10, as shown in FIG. 1, the mask 20 is grounded. By applying a predetermined voltage to the electrodes 12a and 12b, an electrostatic force for adsorbing the mask 20 on the bottom surface of the dielectric ceramic body 11 is applied to the dielectric ceramic. Occurs at the bottom of body 11.

[0025] A switch 13a, 13b is provided with a force S in the middle of the wiring connecting the power supply 14 and the electrodes 12a, 12b, respectively. By turning on and off the switches 13a, 13b separately, the electrodes 12a, A voltage can be applied to each of the terminals 12b independently. FIG. 1 shows a configuration in which one power source 14 also applies a voltage to the electrodes 12a and 12b. The power source for driving the electrode 12a and the power source for driving the electrode 12b may be separated.

The materials used for the electrodes 12 a and 12 b are determined depending on the material used for the dielectric ceramics 11 and the method for manufacturing the electrostatic chuck 10. As a method of manufacturing the electrostatic chuck 10, a dielectric ceramic powder is formed into a sheet by a known doctor blade method, extrusion molding method, or the like, and a predetermined electrode paste is printed on the obtained green sheet in a predetermined pattern. A predetermined number of green sheets on which the electrode paste is not printed are stacked, a green sheet on which the electrode paste is printed is stacked thereon, and further a predetermined number of green sheets are stacked on which the electrode paste is printed. There is a method in which these are integrally formed by a hot press treatment or the like, and the dielectric ceramics and the electrodes are simultaneously fired.

[0027] In such a simultaneous firing method, the electrodes 12a and 12b can be formed with high positional accuracy by screen printing or the like. In the simultaneous firing method, the material used for the electrodes 12a and 12b is a high melting point metal such as tungsten, molybdenum, or iridium that can withstand firing of the dielectric ceramic body 11, or a high melting point conductive material such as titanium nitride or silicon molybdenum. It is necessary to use arsenic compounds.

[0028] As another method of manufacturing the electrostatic chuck 10, there is a method of embedding metal foils / metal nets serving as the electrodes 12a and 12b at predetermined positions in the dielectric ceramic powder, press-forming and firing. . However, in this method, care must be taken to maintain high positional accuracy of the metal foil and the like.

Next, a method of driving the electrodes 12a and 12b when the mask 20 is attracted and held by the electrostatic chuck 10 will be described.

When the mask 20 is brought close to the electrostatic chuck 10 fixed at a predetermined position, a method of supporting (or holding) the central portion of the mask 20 and a method of supporting the peripheral portion of the mask 20 are provided. In the former case, the pattern formed on the mask 20 is May be damaged. Therefore, the latter method is usually adopted, but in this case, the mask 20 is bent by its own weight so that the center thereof is convex downward.

On the other hand, since the bottom surface of the dielectric ceramic body 11 is formed in a concave shape as described above, when the mask 20 is close to the electrostatic chuck 10, the center of the mask 20 and the electrostatic chuck The distance from the center of the suction surface of 10 is wider than the distance between these peripheral parts. In this state, if the mask 20 is attracted to the entire attracting surface of the electrostatic chuck 10 at a stretch, the mask 20 may be displaced or stress may be applied to the mask 20, which is not preferable.

Therefore, first, a voltage is applied only to the electrode 12a, and the substantially central portion of the mask 20 is suction-held at the center of the suction surface of the electrostatic chuck 10. Thereafter, a voltage is applied to the electrode 12b, and the non-sucked portion of the mask 20 is sucked and held outside the center of the suction surface of the electrostatic chuck 10. As a result, unnecessary stress is not applied to the mask 20, and the displacement of the mask 20 can be prevented.

FIGS. 1 and 3 show two independently drivable electrodes 12a and 12b. In order to attract the mask 20 to the electrostatic chuck by the above-described method of attracting the mask 20, the dielectric ceramic body is used. Alternatively, three or more electrodes that can be independently driven may be provided substantially concentrically, and these may be sequentially driven toward the outside of the central force.

In the above-described electrostatic chuck 10, the dielectric ceramic body 11 having a smooth curved suction surface is used. For example, as shown in a schematic bottom view of FIG. It is also possible to use a dielectric ceramic body 11 'in which a pin 15 (cylindrical projection) is formed by the turn and a rib 16 (annular projection) is formed on the outer periphery thereof. Such pins 15 and ribs 16 can be formed by sandblasting the bottom surface of the dielectric ceramic body 11 or the like. In the dielectric ceramic body 11 /, the curved surface connecting the pin 15 and the apex of the rib 16, that is, the curved surface connecting the point in contact with the mask 20 (not shown) may be concave.

[0033] In the dielectric ceramic body 11 'on which the pins 15 and the ribs 16 are formed as described above, the dielectric ceramic body 11' is further provided with a gas supply hole 17a and a gas discharge hole 17b penetrating in the thickness direction. Preferably. While the mask 20 (not shown) is held by the pins 15 and the ribs 16, the cooling gas (for example, By supplying a nitrogen gas) and exhausting the cooling gas flowing between the pins 15 from the gas exhaust holes 17b, the mask 20 (not shown) and the dielectric ceramics 11 'can be cooled.

Next, an embodiment of an EUV light lithography system including the electrostatic chuck 10, that is, a projection exposure apparatus using EUV light as illumination light for exposure will be described. FIG. 5 is a schematic diagram showing a schematic configuration of the EUV optical lithography system 120. The EUV optical lithography system 120 uses the image optical system 122 to form a reduced image of the pattern of the reflective mask 124 (reticle).

In general, EUV light is a force that refers to light having a wavelength in the range of 0.1 to 400 nm. The wavelength of EUV light used as illumination light for exposure in the EUV light lithography system 120 is 1 nm— It is desirable to be in the range of 50 nm. Such EUV light is generated by, for example, a laser plasma X-ray source. The laser plasma X-ray source has a laser source 136 serving as an excitation light source, a xenon gas supply device 138, and a nozzle 142 for discharging xenon gas supplied from the xenon gas supply device 138.

[0036] The laser source 136 generates laser light having a wavelength equal to or shorter than ultraviolet light. For example, a YAG laser or an excimer laser is used. The laser light emitted from the laser source 136 is condensed and applied to the flow of xenon gas emitted from the nozzle 142. As a result, xenon gas plasma is generated, and photons of EUV light are emitted when excited xenon gas molecules fall to a low energy state. Since EUV light has low transmittance in the atmosphere, a region for generating xenon gas plasma is provided in the vacuum chamber 140.

[0037] In the vacuum chamber 140, a parabolic mirror 144 for condensing EUV light generated by the plasma is arranged. The parabolic mirror 144 constitutes a condensing optical system, and is arranged such that the focal position is near the position where xenon gas is emitted from the nozzle 142. The parabolic mirror 144 includes a multilayer film suitable for reflecting EUV light, typically on the concave surface of the parabolic mirror 144. EUV light is reflected by this multilayer film and reaches a collector mirror 146 through a window 141 of a vacuum chamber 140. The window 141 may be an opening through which the laser plasma X-ray source can pass without interference.

[0038] As described above, since EUV light has low transmittance in the atmosphere, EUV light is not transmitted. The passing light path is preferably maintained in a vacuum atmosphere. Therefore, an optical path through which EUV light passes is provided in a vacuum chamber 132, and the vacuum chamber 132 is maintained at a predetermined degree of vacuum by using a pressure reducing device of a vacuum pump 134. Preferably, the vacuum chamber 140 is separated from the vacuum chamber 132. This is because dust tends to be generated by the nozzle 142 that discharges xenon gas.

The condenser mirror 146 collects the EUV light that has arrived from the parabolic mirror 144 and reflects the EUV light to the reflective mask 124. The EUV light reflected by the condenser mirror 146 illuminates a predetermined portion of the reflective mask 124. The parabolic mirror 144 and the condensing mirror 146 constitute an illumination system in the EUV optical lithography system 120.

The reflective mask 124 is held by suction on the lower surface of the electrostatic chuck 10 provided on the mask stage. When the EUV light is reflected by the reflective mask 124, the EUV light is patterned by the pattern data from the reflective mask 124. The patterned EUV light reaches the wafer W mounted on the wafer stage 130 through the image optical system 122.

FIG. 5 shows an example of the image optical system 122 in which four reflecting mirror forces are also configured. The EUV light reflected by the reflective mask 124 is reflected in the order of the concave first mirror 150a, the convex second mirror 150b, the convex third mirror 150c, and the concave fourth mirror 150d to form a reduced image of the mask pattern. Form.

The exposure processing of the wafer W is typically performed by step scanning. In this case, the illumination system irradiates a predetermined area of the reflective mask 124 with EUV light to project a mask pattern onto an exposure area of the eno and W, and during the exposure, the electrostatic chuck 10 and the wafer stage 130 The image optical system 122 moves at a predetermined speed in accordance with the reduction ratio of the image optical system 122 in phase with each other. Here, scanning of the reflective mask 124 and the wafer W is performed with respect to the image optical system 122 in one degree of freedom. When all the regions of the reflective mask 124 are exposed to predetermined regions of the wafer W, exposure of the pattern on the dies of the wafer W is completed. Next, exposure proceeds to the next die on wafer W. It is preferable that the wafer stage 130 holding the wafer W is movable in the X, Υ, and Z directions. In such an exposure process, the wafer W is placed behind the partition 152 so that gas generated from the resist on the wafer W does not affect the mirrors 150a to 150d of the image optical system 122. It is desirable to be arranged in. The partition 152 has an opening 152a, and EUV light is emitted from the concave fourth mirror 150d to the wafer W through the opening 152a. The space inside the partition 152 is evacuated by a vacuum pump 154. As a result, gaseous dust generated by irradiating a resist film (not shown) provided on the surface of the ueno or W is adhered to each of the mirrors 150a to 150d and the reflection type mask 124, thereby causing an optical phenomenon. Poor performance is prevented.

Example

Examples will be described with reference to Examples and Comparative Examples.

In manufacturing the electrostatic chuck, the raw material powder of the dielectric ceramic body includes lithium aluminosilicate having a negative coefficient of thermal expansion and silicon carbide having a positive coefficient of thermal expansion, which have a coefficient of thermal expansion of 20-26 ° C. using those formulated to be ^{0. 5 X 10- 6 -0. 5} X 10- 6 range. As the electrode material, a 30 mm φ tungsten mesh and a tungsten mesh having a 152 × 152 mm opening and a 40 mm φ hole at the center were used.

[0043] In the electrostatic chuck, the raw material powder is put into a predetermined mold and formed by a uniaxial press, and the tungsten electrode is placed on the green body as shown in FIG. The raw material powder was filled and baked by hot press. The sintered body thus obtained was ground to 160 mm X 160 mm X 20 mm. The tungsten mesh electrode was placed at a depth of 2 mm from the surface to be the adsorption surface. Opposite surface force of adsorption surface To insert terminals for supplying power to each electrode, make a 4 mm φ hole in the sintered body and insert a 3.8 mm φ metal pin into each hole. Was connected to each electrode.

[0044] Two electrostatic chucks were produced in this manner, and one of the chucks (Example) was formed into a concave shape such that the suction surface was 80 nm deeper than its peripheral edge. . The remaining one (comparative example) was processed so that the adsorption surface had a flatness of 40 nm or less.

The mask was sucked onto each of the electrostatic chucks of the examples and the comparative examples thus manufactured, and the flatness of the mask was measured using a laser interferometer. Here, a mask having a flatness of 40 nm or less in a 152 XI 52 mm area was determined to be acceptable. The mask is made of glass, has a shape of 152 mm × 152 mm × 6.3 mm, has a Young's modulus of 80 GPa, and has a thickness of several tens / A zm conductive film was used. In addition, as a method of applying voltage to the two electrodes provided on the electrostatic chuck, a predetermined voltage is first applied to a 30 mm φ tungsten mesh electrode arranged at the center, and a predetermined time has elapsed since then. Thereafter, a method of applying a predetermined voltage to a tungsten mesh electrode having a 152 × 152 mm opening was used. The electrostatic chucks of the example and the comparative example were constrained at three points on the side surfaces, as indicated by arrows in the plan view of FIG.

[0046] As a result of measuring the flatness of the masks sucked and held on the electrostatic chucks of the example and the comparative example, the flatness of the mask was less than 40 nm in the example. The flatness of the comparative example was greater than 40 nm. It has grown. As a result, it was confirmed that the mask could be held with high precision by making the suction surface of the electrostatic chuck concave.

As described above, the present invention has been described in detail. However, the above-described embodiment and its modifications are merely examples of the present invention, and the present invention is not limited thereto. Obviously, modifications can be made without departing from the scope of the present invention.

Industrial applicability

[0047] As described above, the electrostatic chuck of the present invention is suitable as a member for a semiconductor manufacturing apparatus, particularly for an exposure apparatus.

Claims

The scope of the claims

[1] An electrostatic chuck in which an adsorption surface for adsorbing and holding an object is formed on a lower surface,

An electrostatic chuck, wherein the suction surface is formed in a concave shape.

[2] The electrostatic chuck according to claim 1,

The electrostatic chuck, wherein the suction surface is formed on a lower surface of a dielectric.

[3] In the electrostatic chuck according to claim 1 or 2,

An electrostatic chuck having a side surface fixed inside a semiconductor manufacturing apparatus.

[4] In the electrostatic chuck according to claim 2 or 3,

The dielectric has a volume resistivity of 1 × 10 ⁹ —1 × 10 ¹⁴ Ω′cm, a Young's modulus of 100 GPa or more, and an average coefficient of thermal expansion at 20 ° C.—26 ° C. of −0.5. X 10- ⁶ - electrostatic chuck, which is a 0. 5 X 10- ^6.

[5] In the electrostatic chuck according to any one of claims 2 and 4,

The object to be adsorbed is a plate-shaped glass having a Young's modulus of less than 100 GPa.

[6] In the electrostatic chuck according to any one of claims 2 and 5,

An electrostatic chuck comprising two or more independently-driveable electrodes arranged substantially concentrically to generate electrostatic force for adsorbing and holding the object to be adsorbed on the dielectric.

[7] An exposure apparatus, comprising the electrostatic chuck according to any one of claims 1 to 6.

[8] The lower surface is a suction surface for sucking and holding the object to be sucked, and the object to be sucked is brought close to the electrostatic chuck having the concave suction surface, so that the object to be sucked is moved to the suction surface. A method of adsorbing an object to be adsorbed,

A suction unit configured to adsorb and hold a substantially central portion of the object to be adsorbed at a center portion of the adsorption surface, and then adsorb and hold an unadsorbed portion of the object to be adsorbed outside the center of the adsorption surface Adsorption method.