Wafer chucks allowing controlled reduction of substrate heating and rapid substrate exchange
First Claim
1. A substrate-holding device for holding a substrate while a fabrication process is being performed on the substrate, the substrate-holding device comprising:
- a wafer-chuck body defining an adhesion surface and comprising an electrostatic electrode, the adhesion surface being configured to contact a downstream-facing surface of a substrate being held by the substrate-holding device by an electrostatic force generated by the electrode;
the adhesion surface defining a channel configured, whenever the substrate is adhered to the adhesion surface by the electrostatic force, to provide a conduit for a heat-transfer gas that, when in the channel, contacts and removes heat from the downstream-facing surface of the substrate;
a gas-supply conduit configured to controllably conduct the heat-transfer gas from a source to the channel;
a gas-evacuation conduit configured to controllably conduct the heat-transfer gas from the channel; and
a controller configured to (i) cause the heat-transfer gas to flow through the channel from the gas-supply conduit during a predetermined time period when the sensitive substrate is being held on the adhesion surface, (ii) at a first predetermined time instant, commence execution of the fabrication process on the substrate being held on the adhesion surface, and (iii) at a second predetermined time instant relative to the fabrication process, commence evacuating the heat-transfer gas from the channel.
1 Assignment
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Accused Products
Abstract
Substrate-holding devices (“wafer chucks”) and methods are disclosed for use in any of various apparatus and methods for processing a substrate. For example, the wafer chucks are especially useful with microlithography apparatus and methods, especially such apparatus and methods employing a charged particle beam. The devices and methods achieve controlled reduction of substrate heating and rapid substrate exchange during substrate processing. The wafer chuck has an adhesion surface and a heat-transfer-gas (HTG) channel. In an exemplary configuration, the HTG channel is connected to an HTG supply and a gas-evacuation system. Heat-transfer gas is caused to flow through the channel during a predetermined time period when the substrate is being held (typically by electrostatic force) on the adhesion surface. At a first time instant, execution of the fabrication process on the substrate (adhered to the adhesion surface) is commenced. At a second time instant relative to the fabrication process, the heat-transfer gas is evacuated from the channel. These time instants can be established to allow wafer-exchange to be performed quickly.
29 Citations
46 Claims
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1. A substrate-holding device for holding a substrate while a fabrication process is being performed on the substrate, the substrate-holding device comprising:
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a wafer-chuck body defining an adhesion surface and comprising an electrostatic electrode, the adhesion surface being configured to contact a downstream-facing surface of a substrate being held by the substrate-holding device by an electrostatic force generated by the electrode;
the adhesion surface defining a channel configured, whenever the substrate is adhered to the adhesion surface by the electrostatic force, to provide a conduit for a heat-transfer gas that, when in the channel, contacts and removes heat from the downstream-facing surface of the substrate;
a gas-supply conduit configured to controllably conduct the heat-transfer gas from a source to the channel;
a gas-evacuation conduit configured to controllably conduct the heat-transfer gas from the channel; and
a controller configured to (i) cause the heat-transfer gas to flow through the channel from the gas-supply conduit during a predetermined time period when the sensitive substrate is being held on the adhesion surface, (ii) at a first predetermined time instant, commence execution of the fabrication process on the substrate being held on the adhesion surface, and (iii) at a second predetermined time instant relative to the fabrication process, commence evacuating the heat-transfer gas from the channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 43, 44)
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8. A microlithography apparatus, comprising:
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an exposure-optical system situated and configured to form an image, on a sensitive substrate, of a pattern using an energy beam;
a wafer chuck comprising an adhesion surface defining a channel, the wafer chuck being situated relative to the exposure-optical system and configured to hold, as the sensitive substrate is being exposed by the energy beam, a downstream-facing surface of the sensitive substrate in contact with the adhesion surface;
a gas-supply conduit configured to controllably conduct a heat-transfer gas from a source to the channel as the sensitive substrate is being held on the adhesion surface, so as to cause the heat-transfer gas to flow through the channel and contact the downstream-facing surface;
a gas-evacuation conduit configured to controllably conduct the heat-transfer gas from the channel; and
a controller configured to (i) cause the heat-transfer gas to flow through the channel from the gas-supply conduit during a predetermined time period when the sensitive substrate is being held on the adhesion surface, (ii) at a first predetermined time instant, commence exposure of the sensitive substrate being held on the adhesion surface, and (iii) at a second predetermined time instant relative to the exposure, commence evacuating the heat-transfer gas from the channel. - View Dependent Claims (9, 10, 11, 12, 13)
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14. In a method for microlithographically exposing a pattern onto a sensitive substrate using an energy beam passing through a projection-optical system that forms an image of the pattern on the sensitive substrate, a method for reducing exposure-induced thermal deformation of the substrate, comprising:
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providing a wafer chuck comprising an adhesion surface defining a channel, the channel being enclosable by a downstream-facing surface of a substrate being held on the adhesion surface;
mounting a sensitive substrate to the adhesion surface such that the downstream-facing surface of the substrate contacts the adhesion surface and encloses the channel;
introducing a heat-transfer gas into the channel such that the heat-transfer gas flowing through the channel contacts the downstream-facing surface of the substrate;
commencing exposure of the sensitive substrate mounted to the wafer chuck;
determining and setting an appropriate time instant, during the exposure, in which to commence evacuation of the heat-transfer gas from the channel in preparation for wafer-exchange; and
at the set time instant, commencing evacuation of the heat-transfer gas from the channel.
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15. A wafer chuck for holding a substrate as a process is being performed on the sensitive substrate, the wafer chuck comprising:
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an adhesion surface configured to contact a downstream-facing surface of the substrate whenever the substrate is mounted to the wafer chuck, the adhesion surface defining a channel that is enclosed whenever a sensitive substrate is mounted to the wafer chuck;
an electrode situated and configured to attract the sensitive substrate by electrostatic attraction such that the substrate is held on the wafer chuck with the downstream-facing surface contacting the adhesion surface, thereby enclosing the channel;
a heat-transfer-gas (HTG)-inlet port situated and configured to introduce a heat-transfer gas into the channel to contact with the downstream-facing surface of the substrate mounted to the adhesion surface;
a gas-evacuation port situated and configured to allow evacuation of heat-transfer gas from the channel; and
a valve mounted to the wafer chuck, the valve being configured to open and close at least one of the inlet port and the evacuation port. - View Dependent Claims (16, 17, 18)
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19. In a microlithography apparatus for exposing a pattern onto a sensitive substrate, a device for holding the sensitive substrate as the pattern is being exposed onto the sensitive substrate, the substrate-holding device comprising:
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a movable wafer stage; and
a wafer chuck mounted to the wafer stage, the wafer chuck comprising (a) an adhesion surface configured to contact a downstream-facing surface of the substrate whenever the substrate is mounted to the wafer chuck, the adhesion surface defining a channel that is enclosed whenever a sensitive substrate is mounted to the wafer chuck;
(b) a heat-transfer-gas inlet port situated and configured to introduce a heat-transfer gas into the channel to contact the downstream-facing surface of the substrate mounted to the adhesion surface;
(c) a heat-transfer-gas evacuation port situated and configured to allow evacuation of heat-transfer gas from the channel; and
(d) a valve mounted to the wafer chuck, the valve being configured to open and close at least one of the inlet port and the evacuation port.
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20. A wafer-processing apparatus, comprising:
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a vacuum chamber configured to be evacuated so as to reduce a pressure inside the vacuum chamber;
a movable wafer stage situated inside the vacuum chamber; and
a wafer chuck mounted to the wafer stage, the wafer chuck comprising (a) an adhesion surface configured to contact a downstream-facing surface of the substrate mounted to the wafer chuck, the adhesion surface defining a heat-transfer-gas (HTG) channel;
(b) an electrode situated and configured to attract the sensitive substrate by electrostatic attraction such that the substrate is held on the wafer chuck with the downstream-facing surface contacting the adhesion surface and enclosing the HTG channel;
(c) an HTG-inlet port situated and configured to introduce a heat-transfer gas into the channel to contact with the downstream-facing surface of the substrate mounted to the adhesion surface;
(d) a gas-evacuation port situated and configured to allow evacuation of gas from the channel; and
(e) a first valve mounted to the wafer chuck, the valve being configured to open and close at least one of the HTG-inlet port and the gas-evacuation port. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A microlithography apparatus, comprising:
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a projection-optical system situated and configured to form an image, carried by an energy beam, on a sensitive substrate;
a wafer chamber situated relative to the projection-optical system and configured to maintain the sensitive substrate at a subatmospheric pressure as the image is being formed on the sensitive substrate by the energy beam;
a movable wafer stage situated inside the wafer chamber;
a wafer chuck mounted on the wafer stage, the wafer chuck comprising an adhesion surface and being configured to attract the sensitive substrate with electrostatic force, thereby causing a downstream-facing surface of the substrate to adhere to the adhesion surface, the adhesion surface defining a heat-transfer-gas (HTG) channel configured such that a heat-transfer gas passing through the HTG channel contacts the downstream-facing surface of the substrate on the adhesion surface;
an HTG-supply system connected via an HTG-inlet valve to the HTG channel and configured to introduce the heat-transfer gas from an HTG supply into the channel;
a gas-evacuation system connected via a gas-evacuation valve to the HTG channel and configured to draw the heat-transfer gas from the channel; and
wherein at least one of the HTG-inlet valve and gas-evacuation valve is mounted on the wafer stage or wafer chuck. - View Dependent Claims (29, 30, 31, 32, 45, 46)
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33. In a method for performing a process on a substrate, a method for holding the substrate, comprising:
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(a) providing an electrostatic wafer chuck comprising an adhesion surface defining a heat-transfer gas channel to which heat-transfer gas is supplied through a heat-transfer-gas (HTG)-inlet valve and HTG-inlet conduit connecting channel to an HTG supply, and from which gas is evacuated through a gas-evacuation valve and a gas-evacuation conduit;
(b) electrostatically attaching the substrate to the adhesion surface;
(c) at time of performing the process on the substrate attached to the adhesion surface, opening the gas-evacuation valve and the HTG-inlet valve to supply heat-transfer gas to the channel; and
(d) while performing the process on the substrate attached to the adhesion surface but after supplying the heat-transfer gas for a predetermined length of time, closing the gas-evacuation valve and applying a vacuum in the gas-evacuation conduit downstream of the gas-evacuation valve. - View Dependent Claims (34, 35, 36, 37)
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38. A substrate-holding device, comprising:
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a wafer chuck comprising an adhesion surface and a heat-transfer-gas (HTG) channel;
an HTG-supply system connected to the channel and configured to supply a heat-transfer gas to the channel; and
a cold trap connected to the HTG-supply system such that heat-transfer gas intended to enter the channel passes through the cold trap before entering the channel, the cold trap being configured to remove impurities from the heat-transfer gas as the gas passes through the cold trap. - View Dependent Claims (39, 40, 41, 42)
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Specification