JP2016100414A - Retainer, vacuum device, lithographic apparatus, and manufacturing method of article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retainer advantageous in exhaustion of a groove of a chuck for fixing a substrate in a vacuum space.SOLUTION: A chuck surface of a static chuck 104, which is a retainer, is so constructed that a wafer 103 is supported with a plurality of pins 201 for reducing pinching of particles 200. A groove that is encapsulated by holding a wafer is formed. The chuck surface of the static chuck includes: a supply passage 203 for providing the groove with a gas; an exhaust passage 206, connected to the supply passage, for exhausting the gas into the vacuum space without going through the groove; and a valve 207 for opening or closing the exhaust passage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a holding device, a vacuum device, a lithographic apparatus, and an article manufacturing method.

  In a holding device for holding a wafer (substrate), Patent Document 1 discloses a technique for supplying a heat transfer gas to a gap between a wafer and an electrostatic chuck for fixing the wafer in order to suppress thermal expansion of the wafer. Yes. Patent Document 1 describes a configuration in which the chuck space is exhausted from the outside of the vacuum chamber in order to prevent heat transfer gas from leaking from the chuck space as much as possible. In this configuration, a gas exhaust pipe is required in addition to the gas supply pipe in the vacuum chamber. Since the electrostatic chuck is mounted on the stage and driven at high speed, the gas piping connected to the electrostatic chuck is also drawn together with the stage. From the viewpoint of stage drive accuracy and dust generation from the piping, fewer gas piping is desirable.

  In Patent Document 2, a configuration in which heat transfer gas is discharged from a gap between a wafer and a chuck for the purpose of simplifying the configuration for exhausting the heat transfer gas from the chuck space and making the temperature distribution in the wafer surface uniform. Is disclosed. There is a known problem that particles are generated on the back surface of the wafer and particles are accumulated on the chuck surface. However, in this configuration, gas is released from the gap, and thus the particles may be scattered.

JP 2001-196290 A JP 2012-195211 A

  When the heat transfer gas in the chuck space is exhausted from a pump outside the vacuum chamber, the exhaust conductance is limited because it is exhausted through piping in the vacuum chamber. In particular, when the pipe diameter is small and the path is long, it takes a long time to exhaust, so the wafer can be removed with the gas remaining in the chuck (groove) and the pipe. In this case, there is a problem that residual gas in the chuck and the piping is released together with particles accumulated (existing) in the chuck, and the particles can adhere to the seal surface of the chuck, the wafer, and the like.

  An object of the present invention is to provide a holding device advantageous for exhausting a groove of a chuck to which a substrate is fixed.

  According to one aspect of the present invention, there is provided a holding device for holding a substrate in a vacuum space, a chuck formed with a groove sealed by holding the substrate, and a supply for supplying gas to the groove It includes a flow path, a discharge flow path connected to the supply flow path for discharging gas into the vacuum space without passing through the groove, and a valve for opening and closing the discharge flow path. A holding device is provided.

  According to the present invention, for example, a holding device that is advantageous for exhausting a groove of a chuck to which a substrate is fixed is provided.

The figure which shows the structure of the charged particle beam drawing apparatus which concerns on 1st Embodiment. The figure which shows the structure of the electrostatic chuck and gas exhaust system in 1st Embodiment. The figure which shows the structure of the electrostatic chuck and lift pin in 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, It shows only the specific example advantageous for implementation of this invention. Moreover, not all combinations of features described in the following embodiments are indispensable for solving the problems of the present invention.

<First Embodiment>
In the following embodiments, a charged particle beam drawing apparatus that is an example of a lithography apparatus that performs pattern formation on a substrate (wafer) with a charged particle beam will be described. However, the present invention can also be applied to a process apparatus such as an etching apparatus, and can be widely applied to a vacuum apparatus including a chuck accommodated in a vacuum vessel and a mechanism for supplying a gas to the chuck, or an apparatus including the same. Is.

FIG. 1 is a diagram showing a configuration of a charged particle beam drawing apparatus having a holding device for holding a substrate in a vacuum space. In FIG. 1, the charged particle beam drawing apparatus 1 has a vacuum chamber 100. The inside of the vacuum chamber 100 is evacuated by the vacuum pump 101, and is maintained at a vacuum degree of about 1e- ⁴ Pa in normal times. The column 102 includes an electron source (not shown) and an electron optical system. An electron beam is emitted from the column 102 and a pattern is drawn on the wafer 103. The wafer 103 is attracted and held on the chuck surface (upper surface) of the electrostatic chuck 104 by an electrostatic force generated by an electrode embedded in the electrostatic chuck. The holding device of the present invention is not limited to an electrostatic chuck. The holding device may be, for example, a device that mechanically holds the outer peripheral portion of the wafer using a claw or a ring. That is, the holding device of the present invention only needs to hold the substrate by at least one of electromagnetic force and mechanical force.

  A space between the back surface of the wafer 103 and the electrostatic chuck 104 is disposed outside the vacuum chamber 100, and from the gas control unit 105 that controls intake and exhaust of the heat transfer gas, the heat transfer gas via the gas pipe 106. Is supplied. The heat transfer gas reduces the thermal resistance between the back surface of the wafer 103 and the electrostatic chuck 104, thereby transferring the heat input to the wafer 103 due to the electron beam irradiation to the electrostatic chuck 104 and increasing the temperature of the wafer 103. Make it smaller. As the heat transfer gas, a gas having a high heat transfer coefficient, such as hydrogen or helium, can be used. Hydrogen is excellent because of its high heat transfer coefficient. Since helium is an inert gas, it is excellent because it has little influence on contamination in the apparatus.

The gas control unit 105 supplies, controls, and exhausts heat transfer gas. The space between the back surface of the wafer 103 and the electrostatic chuck 104 is controlled by the gas control unit 105 so as to maintain, for example, 2e ³ Pa from the heat transfer coefficient necessary for suppressing the thermal stress deformation of the wafer.

  The electrostatic chuck 104 that holds the wafer 103 is held on the top plate 107 of the stage 108. Since the electrostatic chuck 104 is moved in the vacuum chamber 100 at a high speed by the stage 108, the gas pipe 106 is moved together with the electrostatic chuck 104 and drawn. In order not to reduce the driving accuracy of the stage 108, it is desirable that the force applied from the cable to the stage is small, and it is desirable that the number of gas pipes is small. In the present embodiment, the gas pipe 106 may be constituted by one fluorine-based resin tube having an inner diameter of 5 mm and a total length of 10 m, for example.

  The gas exhaust system 109 exhausts residual gas in the electrostatic chuck 104. The gas exhaust system 109 is disposed as close to the electrostatic chuck 104 as possible so that the exhaust conductance can be increased by shortening the exhaust gas path in order to reduce the amount of exhaust gas. In the present embodiment, the gas exhaust system 109 is disposed on the top plate 107 together with the electrostatic chuck 104.

  The wafer 103 is transferred from the load lock chamber 111 into the vacuum chamber 100 by the transfer robot 110 and placed on the electrostatic chuck 104. After being attracted and held on the chuck surface, the insulating film on the back surface is broken and grounded for the purpose of preventing charging by a conduction pin (not shown). Thereafter, heat transfer gas is supplied from the gas control unit 105 to the gap between the back surface of the wafer 103 and the electrostatic chuck 104 via the gas pipe 106. After the supplied gas reaches a predetermined pressure in the chuck, a pattern is drawn on the wafer 103 by electron beam irradiation. After the drawing by the electron beam is completed, the heat transfer gas sealed in the gap between the wafer 103 and the electrostatic chuck 104 is exhausted through the gas exhaust system 109. After exhausting the heat transfer gas, the wafer 103 is removed from the chuck surface by a lift pin (not shown) and transferred from the vacuum chamber 100 to the load lock chamber 111 by the transfer robot 110.

  Hereinafter, the configuration of the electrostatic chuck 104 and the gas exhaust system 109 in this embodiment will be described in detail with reference to FIG. Particles 200 generated due to friction with the wafer 103, destruction of the insulating film for grounding the back surface of the wafer, or the like can accumulate on the electrostatic chuck 104. The chuck surface has a structure in which the wafer 103 is supported by a plurality of pins 201 in order to reduce the pinching of the particles 200. A gas flow path 220 is formed on the chuck surface in the gap between the wafer 103 through which the heat transfer gas passes and the electrostatic chuck 104. The gas flow path 220 is formed as a groove sealed by holding the substrate. In order to enclose the heat transfer gas between the wafer 103 and the electrostatic chuck 104, the outer periphery of the chuck is a seal surface 202 having the same height as the pins 201.

  A supply channel 203 for supplying gas to the gas channel 220 is formed inside the electrostatic chuck 104. The supply channel 203 is connected to the outside of the vacuum chamber 100 through the gas pipe 106 and the feedthrough 204.

  A main valve 205 is provided in the path between the electrostatic chuck 104 and the feedthrough 204. Further, a discharge flow path 206 is provided between the main valve 205 and the electrostatic chuck 104 and connected to the supply flow path 203 to discharge the heat transfer gas into the vacuum chamber without passing through the gas flow path 220. . The discharge flow path 206 is provided with a leak valve 207 that can block the flow of heat transfer gas in the flow path. The gas exhaust system 109 shown in FIG. 1 includes a main valve 205, a discharge passage 206, and a leak valve 207.

  Outside the vacuum chamber 100, a three-way valve 208, a flow rate control unit 209, an exhaust pump 210, and a gas cylinder 211 are connected via a feedthrough 204. These components constitute a gas control unit 105 that supplies, controls, and exhausts heat transfer gas. A gas supply system that supplies heat transfer gas to the chuck surface includes a heat transfer gas passage 203, a gas pipe 106, a feedthrough 204, a three-way valve 208, a flow rate control unit 209, and a gas cylinder 211.

The control unit 250 comprehensively controls the operation of each unit of the charged particle beam drawing apparatus 1. When the wafer 103 is attracted to the electrostatic chuck 104 and heat transfer gas is supplied between the wafer back surface and the chuck surface, the main valve 205 is opened and the leak valve 207 is closed. The three-way valve 208 is opened on the flow control unit 209 side and closed on the exhaust pump 210 side. The heat transfer gas is supplied from the gas cylinder 211 and is controlled by the flow rate control unit 209 so as to keep the pressure in the chuck inner space at, for example, 2e ³ Pa.

  When drawing by the electron beam is completed and the wafer 103 is removed from the electrostatic chuck 104, the flow control unit 209 side is closed by the three-way valve 208, the exhaust pump 210 side is opened, and heat transfer in the gas pipe 106 and the electrostatic chuck is performed. Exhaust the gas. At this time, the gas pipe 106 has a small exhaust conductance, and the time required for exhaust is limited due to the limitation of the apparatus throughput. Therefore, it is difficult to evacuate the space between the wafer 103 and the electrostatic chuck 104 to the same pressure as the space in the vacuum chamber by the evacuation pump 210. If the wafer 103 is removed in a state where the heat transfer gas remains in the space between the gas pipe 106, the heat transfer gas flow path 203, and the wafer 103 and the electrostatic chuck 104, a problem of particles may occur. Specifically, at this time, the particles 200 accumulated in the space between the wafer back surface and the electrostatic chuck may be released together with the residual gas from the gap between the chuck surfaces, and may adhere to the seal surface 202 and the surface of the wafer 103. .

  Therefore, in this embodiment, in order to avoid the release of residual gas from the chuck surface, the main valve 205 is closed and the leak valve 207 is opened after roughing the inside of the chuck to about 10 Pa. Residual gas is exhausted through the exhaust passage 206 into the vacuum chamber 100, which is a large vacuum buffer. The conductance is larger than that of the exhaust pump 210 from the outside of the vacuum chamber 100, and the amount of residual gas to be discharged is limited to the space on the electrostatic chuck 104 side from the main valve 205. It can be exhausted until the same pressure as inside.

Here, the conditions of the present embodiment are assumed to be, for example, a piping volume 2E ⁻⁴ m ³ , a residual gas pressure 10 Pa, a vacuum chamber volume 5 m ³ , and a vacuum chamber normal pressure 1E ⁻⁴ Pa). Under this condition, when the residual gas is discharged into the vacuum chamber 100 at once, the pressure in the vacuum chamber temporarily rises to about 5 times. By gradually releasing the residual gas (slow leak), the ultimate pressure of the vacuum chamber can be suppressed. When the effective exhaust speed of the vacuum chamber is 2 m ³ / s and the outgas from the chamber is ignored, when the residual gas is released over 2 seconds, the pressure increase in the vacuum chamber is suppressed to about twice the normal pressure. it can. For the slow leak, the discharge gas flow rate may be adjusted by the leak valve 207, or a separate filter may be provided in the discharge flow path 206.

  Since the residual gas is not released from the chuck surface, the release of most of the particles in the chuck can be suppressed, but a small amount of particles may also be released from the discharge channel 206. Therefore, a dust removal filter 212 may be attached to the discharge flow path 206 so that particles accumulated in the chuck in the discharge flow path 206 are not released into the vacuum chamber 100. The dust removal filter 212 may be a particulate removal filter that is generally used in a semiconductor manufacturing apparatus, and captures particles while allowing gas to pass through a fibrous metal, polymer, or porous ceramic.

  In the present embodiment, the main valve 205 and the leak valve 207 are used as the gas exhaust system 109, but a three-way valve may be used at the intersection of the gas pipe 106 and the discharge flow path 206 instead.

Second Embodiment
Next, a second embodiment will be described. Here, differences from the first embodiment will be described. The leak valve 207 is, for example, a normally open type (normally open type) valve that opens when not energized and closes when energized. When the heat transfer gas is sealed in the gap between the wafer 103 and the electrostatic chuck 104, the pressure in the gap and the pressure in the vacuum chamber are 2e ³ Pa and 1e ^-4 Pa, respectively. There is a pressure difference. If the device loses power in this state, the electrostatic chuck loses its attractive force, and if the leak valve 207 is closed, the pressure difference between the front side and the back side of the wafer cannot be resolved, and the wafer may drop or break. There is. At this time, since the leak valve 207 is closed, the enclosed heat transfer gas is released from the chuck surface. As the heat transfer gas is released, the particles in the chuck are diffused to the outside.

  Therefore, by making the leak valve 207 a normally open type valve, even if the electrostatic chuck 104 loses its adsorption power at the time of a power failure, the heat transfer gas in the chuck is released from the leak valve 207. It is possible to prevent the wafer from falling.

<Third Embodiment>
Next, a third embodiment will be described with reference to FIG. Here, differences from the first embodiment will be described. The following gas flow paths are formed inside the electrostatic chuck of the present embodiment. The supply channel 301 is a channel for supplying heat transfer gas to the gap between the wafer back surface and the electrostatic chuck. The discharge channel 302 is a channel for discharging heat transfer gas from the gap. The gas flow path 303 is a flow path that connects the supply flow path 301 and the discharge flow path 302 to the gap between the wafer back surface and the electrostatic chuck.

  In addition, a switching valve 320 that selectively switches the connection destination of the gas flow path 303 between the supply flow path 301 and the discharge flow path 302 is provided inside the electrostatic chuck. The switching valve 320 is a spool valve that has a seal member 305 attached to the inner wall of the cylindrical valve box 304 and switches the flow path by driving a skewer-shaped valve body 306 in the axial direction. The charged particle beam drawing apparatus 1 according to the present embodiment includes lift pins 307 as lifting parts for unloading the wafer 103 from the electrostatic chuck 104. The lift pin 307 is supported by the support member 308, and the lift pin 307 is moved up and down by driving the actuator 309. In the present embodiment, the valve body 306 of the switching valve 320 is also supported by the support member 308 common to the lift pin 307. Therefore, the switching valve 320 controls the gas flow in the supply flow path 301 and the discharge flow path 302 in conjunction with the lifting and lowering operation of the lift pins 307. On the chuck surface, a ring-shaped lift pin seal surface 310 is provided around the lift pins 307 to separate the lift pin space and the space between the chuck and the wafer.

  When the heat transfer gas is supplied to the gap between the back surface of the wafer and the electrostatic chuck, the lift pins 307 are settled inside the chuck together with the support member 308 as shown in FIG. The valve body 306 connects the supply channel 301 to the gap between the back surface of the wafer and the electrostatic chuck, and is held at a position where the discharge channel 302 is closed.

  When the wafer is lifted from the chuck by the lift pins 307, as shown in FIG. 3B, the valve body 306 rises together with the lift pins 307, closes the supply flow path 301 and simultaneously connects the discharge flow path 302 to the chuck gap. At this time, the flow path of the heat transfer gas is switched by the valve prior to the wafer detachment by the lift pins 307, and the heat transfer gas sealed in the gap is discharged from the discharge flow path 302 into the vacuum chamber.

  Thus, the valve is closed so that the gas is supplied from the supply flow path 301 to the groove while the chuck groove is sealed by holding the wafer. Further, before the wafer is released from the chuck, the valve is opened so that the gas is discharged from the groove into the vacuum chamber via the discharge flow path 302. With the above configuration, the heat transfer gas flow path can be switched by using one actuator 309 for driving the lift pin 307 without using a vacuum valve having an actuator individually. It becomes possible. Moreover, according to the said structure, the lift pin 307 and the valve body 306 are driven integrally. This prevents a synchronization error between the valve opening / closing operation and the lift pin drive, that is, a malfunction in which the heat transfer gas is supplied while the wafer is lifted or the wafer lift operation is performed before the heat transfer gas is released. .

<Embodiment of Method for Manufacturing Article>
The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing an article such as a microdevice such as a semiconductor device or an element having a fine structure. The article manufacturing method of the present embodiment includes a step of transferring an original pattern onto a substrate using the above-described lithography apparatus (exposure apparatus, imprint apparatus, drawing apparatus, etc.), and a substrate on which the pattern is transferred in such a process. Process. Further, the manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

100: vacuum chamber, 103: wafer, 104: electrostatic chuck, 105: gas control unit, 106: gas piping, 205: main valve, 206: discharge flow path, 207: leak valve

Claims (12)

A holding device for holding a substrate in a vacuum space,
A chuck formed with a groove to be sealed by holding the substrate;
A supply flow path for supplying gas to the groove;
A discharge flow path connected to the supply flow path for discharging gas into the vacuum space without passing through the groove;
A valve for opening and closing the discharge channel;
A holding device comprising:   Before the substrate is released from the chuck, the valve is closed so that the gas is supplied to the groove from the supply flow channel in a state where the groove is sealed by holding the substrate, The holding device according to claim 1, wherein the valve is opened so that gas is discharged from the groove into the vacuum space through the discharge channel.   The holding device according to claim 1, wherein the discharge channel includes a dust filter.   The holding device according to any one of claims 1 to 3, wherein the valve is a normally open valve. And further includes an elevating part for unloading the substrate from the chuck,
The holding device according to any one of claims 1 to 3, wherein opening and closing of the valve is configured to be interlocked with a lifting operation of the lifting unit.   The holding device according to claim 5, wherein the valve is supported by a support member common to the elevating unit.   The holding device according to claim 5 or 6, wherein the valve is configured to be opened before the substrate is released from the chuck by the elevating unit.   The holding device according to any one of claims 1 to 7, wherein at least one of hydrogen and helium is supplied to the groove through the supply flow path.   The holding device according to claim 1, wherein the substrate is held by at least one of an electromagnetic force and a mechanical force. A holding device according to any one of claims 1 to 9,
A vacuum vessel containing the holding device;
A vacuum apparatus comprising:   A lithographic apparatus comprising the vacuum apparatus according to claim 10, wherein pattern formation is performed on a substrate in a vacuum space. Forming a pattern on a substrate using the lithography apparatus according to claim 11;
Processing the substrate on which the pattern has been formed in the step;
A method for producing an article comprising:

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