JP2011249620A - Exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool a reticle R with more efficiency.SOLUTION: An exposure device includes: a partition member 101 that exists between a reticle stage RST and a second condenser lens CL and forms a substantially hermetically sealed space SA between the reticle stage RST and the second condenser lens CL within a scanning range of the reticle stage RST; and air supply passages 111 that supply dry air into the space SA hermetically sealed by the partition member 101. The space SA is a space, through which illumination light EL from an illumination optical system ILS passes, and forms a first space SA1, to which dry air is supplied from the air supply passages 111, and a second space SA2 that communicates with the first space SA1 and forms a flow of the dry air from the first space SA1, with a flow cross-sectional area O2 of the dry air in the second space SA2 being smaller than a flow cross-sectional area O1 of the dry air in the first space SA1.

Description

  The present invention relates to an exposure apparatus for transferring and exposing a pattern image formed on a reticle onto a substrate.

  In a lithography process, which is one of manufacturing processes for devices such as semiconductor elements, an exposure apparatus that transfers and exposes an image of a pattern formed on a photomask or a reticle (hereinafter, collectively referred to as a reticle) onto a substrate coated with a resist. Is used. As this exposure apparatus, a step-and-repeat type reduction projection exposure apparatus, a step-and-scan type scanning projection exposure apparatus, and the like are known.

  In such an exposure apparatus, thermal distortion or thermal expansion may occur in the reticle when the reticle is irradiated with illumination light. Specifically, when the reflectance of the reticle with respect to the illumination light is low, a temperature difference is generated between the area irradiated with the illumination light and the area not irradiated with the reticle, thereby causing heat in the in-plane direction of the reticle. Distortion may occur. When transfer exposure is performed in a state where thermal distortion or thermal expansion occurs on the reticle, a distorted pattern image is transferred and exposed on the substrate, and pattern overlay accuracy and splicing accuracy are reduced.

  For this reason, the conventional exposure apparatus is provided with an air conditioner that supplies a temperature-controlled gas controlled within a predetermined temperature range to the reticle surface. According to such an air conditioner, it is possible to suppress the occurrence of thermal distortion and thermal expansion by cooling the reticle surface with the temperature control gas, so that the pattern overlay accuracy and splicing accuracy are reduced. Can be suppressed.

International Publication No. 2006/28188

  However, even in the conventional exposure apparatus, further improvement in efficiency is desired for cooling by the air conditioner.

  The present invention has been made in view of the above problems, and an object thereof is to provide an exposure apparatus that can cool a reticle more efficiently.

  In order to solve the above problems and achieve the object, an exposure apparatus according to the present invention scans a reticle stage, a reticle stage on which a reticle carried from the outside is placed, an illumination optical system that illuminates the surface of the reticle, and the reticle stage. And a partition member interposed between the reticle stage and the illumination optical system, and forming a substantially sealed space between the reticle stage and the illumination optical system within the scanning range of the reticle stage, and a partition wall An air supply path that supplies gas into a space sealed by the member, and the space is a space through which illumination light from the illumination optical system passes and is a first space in which gas is supplied from the air supply path And a second space that communicates with the first space and forms a gas flow from the first space, and the gas cross-sectional area of the second space is greater than the gas cross-sectional area of the first space. Small thing And features.

  The exposure apparatus according to the present invention can cool the reticle more efficiently.

FIG. 1 is a schematic side sectional view showing the overall configuration of an exposure apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the control system of the exposure apparatus shown in FIG. FIG. 3 is a schematic cross-sectional view showing the configuration of the reticle stage apparatus. FIG. 4 is a schematic perspective view showing the configuration of the reticle stage. FIG. 5 is a diagram showing the flow of dry air when the reticle stage is scanned in the -Y direction. FIG. 6 is a diagram showing the flow of dry air when the reticle stage is scanned in the + Y direction.

  Hereinafter, a configuration of an exposure apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[Overall configuration of exposure apparatus]
First, the overall configuration of an exposure apparatus that is an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a schematic side sectional view showing the overall configuration of an exposure apparatus according to an embodiment of the present invention. As shown in FIG. 1, an exposure apparatus 1 according to an embodiment of the present invention includes a chamber 2, a light source unit 3, an illumination optical system ILS, a reticle stage apparatus 4, a projection optical system PL, and a wafer stage WST. With. In the following, the normal direction of the bottom surface of the chamber 2 is defined as the Z-axis direction, and the directions perpendicular to and parallel to the paper surface of FIG. It is defined as the axial direction. In addition, the rotation directions around the X axis, the Y axis, and the Z axis are expressed as a θx direction, a θy direction, and a θz direction, respectively.

  The chamber 2 is installed on the floor FL. On the floor FL in the chamber 2, a lower frame 12 is installed via a pedestal 11. A flat base member 13 is fixed to the central portion of the lower frame 12. A flat wafer base WB is supported on the base member 13 via a vibration isolator 14. Wafer stage WST is mounted on an upper surface parallel to the XY plane of wafer base WB via an air bearing (not shown) so as to be movable in the X-axis direction and the Y-axis direction and rotatable in the θz direction.

  An optical system frame 16 is supported on the upper end of the lower frame 12 via a vibration isolator 15 arranged so as to surround the wafer base WB. A projection optical system PL is disposed in the opening at the center of the optical system frame 16. An upper frame 17 is fixed on the optical system frame 16 so as to surround the projection optical system PL.

  Air conditioners 20 </ b> A, 20 </ b> B, and 20 </ b> C for performing air conditioning in the chamber 2 are disposed on the upper surface of the chamber 2. The air conditioner 20A supplies clean air whose temperature is controlled in the chamber 2 through a plurality of openings 21 formed on the upper surface of the chamber 2 in a downflow manner. The air conditioner 20 </ b> B supplies nitrogen gas to the illumination optical system ILS via the air supply path 22. The air conditioner 20 </ b> C supplies dry air to the reticle stage device 4 via the air supply path 23.

  The light source unit 3 is installed on the floor FL outside the chamber 2. The light source unit 3 includes a laser light source that generates ArF excimer laser light as illumination light EL for exposure, a beam transmission optical system that guides the illumination light EL to the illumination optical system ILS, and a cross-sectional shape of the illumination light EL that has a predetermined shape. A beam shaping optical system for shaping. An emission end of the illumination light EL of the light source unit 3 is disposed in the chamber 2 through an opening at the upper side surface in the + Y direction of the chamber 2. As the light source of the illumination light EL, an ultraviolet pulse laser light source such as a KrF excimer laser light source, a harmonic generation light source of a YAG laser, a harmonic generation device of a solid laser, or a mercury lamp can be used.

  The illumination optical system ILS is disposed in the upper part of the chamber 2 and includes an illuminance uniformizing optical system including an optical integrator and the like, a reticle blind, a first condenser lens, a mirror ME for bending an optical path, a second condenser lens CL, and the like. A plurality of optical members are provided. These optical members are supported in the illumination system barrel 5. The interior of the illumination system barrel 5 is controlled within a predetermined temperature and humidity range by supplying nitrogen gas from the air conditioner 20 </ b> B through the air supply path 22. The illumination optical system ILS illuminates a slit-shaped illumination area elongated in the X direction on the reticle R defined by the reticle blind with illumination light EL with a substantially uniform illuminance.

  The reticle stage device 4 is disposed on the object plane side of the projection optical system PL. The reticle stage device 4 includes a mechanism for holding the reticle R carried in from the outside, and a scanning mechanism (not shown) for moving the reticle R with a predetermined stroke in the Y-axis direction and a small amount in the X-axis direction and the θz direction. Is provided. On the reticle R, a predetermined pattern such as a circuit pattern of an electronic device is formed. The illumination light EL from the illumination optical system ILS that has passed through the reticle R is guided to the projection optical system PL.

  The projection optical system PL is configured by holding a plurality of mirrors with a lens barrel. Projection optical system PL is a non-telecentric and telecentric reflection system on reticle R side and wafer W side, respectively, and its projection magnification is a reduction magnification such as 1/4. The projection optical system PL forms a reduced image of a part of a predetermined pattern formed on the reticle R in the exposure area by irradiating the exposure area on the wafer W with the illumination light EL.

  The projection optical system PL includes an optical characteristic adjustment mechanism (not shown) for adjusting optical characteristics such as wavefront aberration, coma aberration, field curvature, distortion, and the like. This optical characteristic adjustment mechanism tilts at least one of the plurality of mirrors with respect to the optical axis AX of the illumination light EL in the projection optical system PL, moves it in a direction parallel to the optical axis AX, The optical characteristics of the projection optical system PL are adjusted by changing the shape of one mirror.

  Wafer stage WST includes a vacuum chuck (not shown) that vacuum-sucks wafer W, a cooling device (not shown) that adjusts the temperature of wafer W via a vacuum chuck (not shown), and moves wafer W with a predetermined stroke in the Y-axis direction. And a scanning mechanism (not shown) for moving in the X-axis direction and the Z-axis direction. The illumination light EL emitted from the projection optical system PL irradiates the surface of the wafer W, whereby a pattern obtained by reducing a predetermined pattern formed on the reticle R to a predetermined magnification is transferred to the wafer W. In the present embodiment, wafer stage WST holds wafer W by vacuum suction, but may hold wafer W by electrostatic suction.

  When exposing one shot area on the wafer W, the illumination light EL shaped in a rectangular shape with the long side in the X-axis direction is irradiated onto the surface of the reticle R from the illumination optical system ILS, and the reticle R and the wafer W are The projection optical system PL is scanned in synchronization with the Y-axis direction at a predetermined speed ratio according to the reduction magnification of the projection optical system PL. In this way, a pattern image based on the predetermined pattern formed on the reticle R is transferred and exposed to one shot area on the wafer W. Thereafter, wafer stage WST is driven to move wafer W stepwise, and then a pattern image based on a predetermined pattern formed on reticle R is transferred and exposed to the next shot area on wafer W. In this way, the reticle R pattern is sequentially formed on a plurality of shot areas on the wafer W by the step-and-scan method.

[Control system configuration]
Next, the configuration of the control system of the exposure apparatus 1 will be described with reference to FIG.

  FIG. 2 is a block diagram showing the configuration of the control system of the exposure apparatus 1 shown in FIG. As shown in FIG. 2, the exposure apparatus 1 includes a signal processing system 51, a reticle autofocus system 52, a reticle interferometer 53, a wafer interferometer 54, and a main controller 55 as a control system. The signal processing system 51 calculates the position of the alignment mark on the wafer W by processing the measurement signal of the alignment system AL, and inputs an electric signal indicating the calculated alignment mark position to the main controller 55.

  The reticle autofocus system 52 calculates a focus position at a plurality of points on the wafer W by processing a detection signal of the autofocus sensor AF, and inputs an electric signal indicating the calculated focus position to the main controller 55. Reticle interferometer 53 detects position information in the XY plane of a reticle stage (or reticle holder, hereinafter referred to as reticle stage) RST that is movable while holding reticle R, and mainly uses an electrical signal indicating the detected position information. Input to the controller 55. Wafer interferometer 54 detects the position information of wafer W and inputs an electrical signal indicating the detected position information to main controller 55.

  The main control device 55 is realized by an arithmetic processing device such as a microcomputer. The main controller 55 controls the overall operation of the exposure apparatus 1. Specifically, main controller 55 performs alignment of wafer W based on the electrical signal input from signal processing system 51. Main controller 55 drives reticle stage drive system 56 based on the electrical signal input from reticle autofocus system 52. The reticle stage drive system 56 controls the Z-direction position of the reticle R within an allowable range by moving the reticle stage RST by driving the linear motor 57.

  Main controller 55 drives reticle stage drive system 56 based on the electrical signal input from reticle interferometer 53. The reticle stage drive system 56 drives the linear motor 57 to move the reticle stage RST along the guide surface parallel to the XY plane with a predetermined stroke in the Y direction, and in the X direction and θz direction as necessary. In addition, the reticle stage RST is moved by a small amount.

  Main controller 55 drives wafer stage drive system 58 based on the electrical signal from wafer interferometer 54. Wafer stage drive system 58 drives linear motor 59 to move wafer stage WST with a predetermined stroke in the X direction and the Y direction, and also moves wafer stage WST in the θz direction as necessary. The main controller 55 controls the air conditioners 20A, 20B, and 20C via the air conditioning control system 60, and thereby the temperature and humidity of the gas (air, nitrogen gas, and dry air) supplied by the air conditioners 20A, 20B, and 20C. Is controlled within a predetermined range.

[Configuration of reticle stage device]
Next, the configuration of the reticle stage apparatus 4 will be described with reference to FIGS.

  FIG. 3 is a schematic cross-sectional view showing the configuration of the reticle stage device 4. FIG. 4 is a schematic perspective view showing the configuration of the reticle stage. As shown in FIG. 3, reticle stage device 4 includes reticle stage RST, partition members 101 and 102, and guide members 103 and 104. As shown in FIG. 4, reticle stage RST is formed of a rectangular frame-like member, and holds a part of the lower surface of reticle R carried in from the outside on holding surface 121 by vacuum suction or the like. Magnet units 57A functioning as a mover of the linear motor 57 are provided on both end surfaces of the reticle stage RST on the ± X direction side. As shown in FIG. 3, the partition member 101 is interposed between the reticle stage RST and the second condenser lens CL constituting the illumination optical system ILS. Partition member 101 forms a substantially sealed space SA between reticle stage RST and second condenser lens CL within the entire scanning range of reticle stage RST by a reticle stage drive system (not shown).

  The space SA forms a first space SA1 through which the illumination light EL irradiated from the second condenser lens CL passes. In the first space SA1, an air supply path 111, an ejection nozzle 112, and a charge removing device 113 are provided. The air supply path 111 supplies dry air A1 from an air conditioner (not shown) into the first space SA1. The ejection nozzle 112 ejects dry air A2 from an air conditioner (not shown) onto a partial surface of the reticle R irradiated with the illumination light EL. In this case, dry air whose temperature is controlled by the air conditioner 20C is blown toward the reticle R. For example, even if the temperature of the reticle R is increased by irradiation with illumination light, the reticle R is It becomes possible to efficiently cool to a predetermined temperature. The charge removing device 113 removes static electricity generated on the surface of the reticle R by supplying a gas containing ions into the first space SA1.

  The space SA forms a second space SA2 that communicates with the first space SA1. A gap is formed between the lower surface of the partition member 101 and the upper surface of the reticle stage RST in the second space SA2 so that the reticle stage RST can scan. Thus, the dry air A1 and A2 supplied from the air supply path 111 and the ejection nozzle 112 circulate from the first space SA1 into the second space SA2, and between the lower surface of the partition wall member 101 and the upper surface of the reticle stage RST. It leaks through the gap formed between them. Further, as shown in FIG. 3, the second space SA2 is designed such that the cross-sectional area O2 of the dry air in the second space SA2 is smaller than the cross-sectional area O1 of the dry air in the first space SA1. ing. In this specification, the distribution cross-sectional area means the cross-sectional area of the flow path of the dry air, that is, the cross-sectional area of the first space SA1 and the second space SA2 in the direction substantially orthogonal to the flow direction of the dry air.

  Partition member 102 is interposed between reticle stage RST and projection optical system PL. In the present embodiment, the partition member 102 functions as a reticle stage surface plate that forms the guide surface of the reticle stage RST. Reticle stage RST is levitated and supported on a reticle stage surface plate by an air bearing (not shown). Partition member 102 forms a substantially sealed space SB between reticle stage RST and projection optical system PL within the entire scanning range of reticle stage RST by a reticle stage drive system (not shown). A gap is formed between the upper surface of the partition wall member 102 and the lower surface of the reticle stage RST in the space SB so that the reticle stage RST can scan. An air supply path 114 is provided in the space SB. The air supply path 114 supplies dry air A3 from an air conditioner (not shown) into the space SB. By supplying the dry air A3 from the air supply path 114, the temperature and humidity in the space SB can be controlled within a predetermined range.

As shown in FIG. 4, the guide member 103 is a plate-like member provided on the upper surfaces of both outer peripheral portions in the ± Y direction of the reticle stage RST, and extends in the ± Y direction. As shown in FIG. 3, the guide member 103 measures the dry air leaking from the gap formed between the lower surface of the partition wall member 101 and the upper surface of the reticle stage RST from the reticle interferometer 53 and the reticle interferometer 53. Leakage to the measurement optical path ML formed between the reflecting mirror 53a that reflects light is suppressed. As shown in FIG. 4, the guide member 104 is a plate-like member provided on the lower surfaces of both outer peripheral portions in the ± Y direction of the reticle stage RST, and extends in the ± Y direction. As shown in FIG. 3, the guide member 104 suppresses the dry air leaking from the gap between the upper surface of the partition member 102 and the lower surface of the reticle stage RST from leaking to the measurement optical path ML side.
In addition, when the exposure apparatus is provided with a measurement apparatus that performs measurement using measurement light, apart from the interferometer, at least one of the measurement lights is used so that dry air does not affect the measurement accuracy of the measurement apparatus. An isolation member may be provided to isolate the dry air from the optical path of the part.

  Reticle stage device 4 having such a configuration operates as follows to suppress the retention of warmed gas on the surface of reticle R, and effectively cools reticle R. Hereinafter, the operation of the reticle stage apparatus 4 when the reticle R is cooled will be described with reference to FIGS. FIG. 5 is a diagram showing the flow of dry air when reticle stage RST is scanned in the -Y direction. FIG. 6 is a diagram showing the flow of dry air when the reticle stage RST is scanned in the + Y direction.

  When the reticle stage RST is scanned by a reticle stage drive system (not shown), as shown in FIGS. 5 and 6, the dry air supplied from the air supply path 111 and the ejection nozzle 112 is based on the same principle as the operation of the piston. The first space SA1 is drawn into the second space SA2 that communicates with the first space SA1. Specifically, when the reticle stage RST is scanned in the −Y direction, as shown in FIG. 5, the dry air moves from the first space SA1 to the second space SA2 formed on the upper surface of the reticle R in the −Y direction. A flow F1 of dry air that is drawn and travels in the -Y direction is formed. Similarly, when reticle stage RST is scanned in the + Y direction, dry air is drawn from first space SA1 into second space SA2 formed on the upper surface of reticle R in the + Y direction, as shown in FIG. A flow F2 of dry air toward the + Y direction is formed.

At this time, the size of the second space SA2 is designed such that the flow cross-sectional area O2 of the dry air in the second space SA2 is smaller than the cross-sectional area O1 of the dry air in the first space SA1. Thereby, the flow rate of the dry air in the second space SA2 becomes faster than the flow rate of the dry air in the first space SA1. For this reason, even when the dry air outlet is located away from the surface of the reticle R, warm air stays on the surface of the reticle R by supplying dry air having a high flow velocity to the surface of the reticle R. Is suppressed, and the reticle R can be cooled effectively.
Note that if the flow rate of the dry air in the second space SA2 is faster than the flow rate of the dry air in the first space SA1, the size of the second space SA2 is not necessarily the same as that in the second space SA2. It is not necessary to configure the air flow cross section O2 to be smaller than the dry air flow cross section O1 in the first space SA1.

  As is apparent from the above description, the exposure apparatus 1 according to an embodiment of the present invention is interposed between the reticle stage RST and the illumination optical system ILS, and within the scanning range of the reticle stage RST, the reticle stage RST and the illumination. A partition member 101 that forms a substantially sealed space SA between the optical system ILS and an air supply path 111 that supplies dry air into the space SA sealed by the partition member 101 is provided. The space SA is a space through which the illumination light EL from the illumination optical system ILS passes, and communicates with the first space SA1 to which dry air is supplied from the air supply path 111 and the first space SA1, and the first space SA1. And a second cross-sectional area O2 of the dry air in the second space SA2 is smaller than a cross-sectional area O1 of the dry air in the first space SA1. It has become.

  According to such a configuration, even if the dry air outlet is located away from the surface of the reticle R, dry air having a high flow rate can be supplied to the surface of the reticle R, so that the surface of the reticle R is heated. Therefore, it is possible to cool the reticle R more efficiently. Further, since the reticle R is disposed in the substantially sealed space SA, the humidity of the periphery of the reticle R is always controlled within a predetermined range, and foreign matters such as ammonium sulfate that grows by using water as a medium are contained in the reticle R. Growth on the pattern can be suppressed.

  An exposure apparatus 1 according to an embodiment of the present invention includes an ejection nozzle 112 that is disposed in the first space SA1 and ejects dry air onto a partial surface of a reticle R irradiated with illumination light EL from the illumination optical system ILS. Prepare. According to such a configuration, it is possible to further suppress the retention of warm air on the surface of the reticle R, so that the reticle R can be cooled more efficiently.

  The exposure apparatus 1 according to an embodiment of the present invention includes the guide member 103 that suppresses the dry air discharged from the second space SA2 from leaking to the measurement optical path ML side of the reticle interferometer 53, so that the dry air is the reticle. Influencing the measurement accuracy of the interferometer 53 can be suppressed.

  The exposure apparatus 1 according to an embodiment of the present invention includes the charge removing device 113 that removes static electricity by supplying a gas containing ions into the first space SA1 and the second space SA2, and thus the surface of the reticle R due to static electricity. Can be prevented from being charged.

The embodiment to which the invention made by the present inventors has been described has been described above, but the present invention is not limited by the description and drawings that form part of the disclosure of the present invention according to the above embodiment. That is, other embodiments, examples, combinations of embodiments, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.
As shown in FIG. 4, the guide member 103 and the guide member 104 are independently provided on both outer peripheral portions in the ± Y direction of the reticle stage RST. However, these may be provided integrally. For example, in the configuration of FIG. 4, a step is formed between the main body portion of the reticle RST and the guide members 103 and 104, but the portions facing the partition wall member 101 and the partition member 102 so that the step is eliminated. Alternatively, they may be configured to have the same surface shape. Accordingly, the dry air flows F1 and F2 can be more smoothly guided to the second space SA2.

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 2 Chamber 3 Light source part 4 Reticle stage apparatus 53 Reticle interferometer 53a Reflective mirror 101,102 Partition member 103,104 Guide member 111,114 Air supply path 112 Jet nozzle 113 Charge removal apparatus CL 2nd condenser lens EL Illumination light F1, F2 Dry air flow ILS Illumination optical system ML Measurement optical path PL Projection optical system RST Reticle stage SA, SB Space SA1 First space SA2 Second space WST Wafer stage

Claims (7)

In an exposure apparatus that exposes an image of a pattern formed on the reticle by moving the reticle and the wafer carried from the outside in a predetermined scanning direction in synchronization with each other,
A reticle holder for placing the reticle;
An illumination optical system for illuminating the reticle;
A scanning mechanism for scanning the reticle holder in the scanning direction;
A partition member interposed between the reticle holder and the illumination optical system, and forming a substantially sealed space between the reticle holder and the illumination optical system within a scanning range of the reticle holder;
An air supply path for supplying gas into the space formed by the partition member,
The space is a space through which illumination light emitted from the illumination optical system and illuminates the reticle placed on the reticle holder passes, and the first space to which the gas is supplied from the air supply path; And a second space that communicates with the first space and forms a flow of the gas from the first space, and a gas cross-sectional area of the gas in the second space An exposure apparatus having a smaller cross-sectional area than a distribution cross section.   2. The gas flow rate in the second space is faster than the gas flow rate in the first space as the reticle holder is scanned by the scanning mechanism. Exposure device. The exposure apparatus according to claim 1, further comprising: an ejection nozzle that is disposed in the first space and ejects a gas to a partial surface of the reticle to which the illumination light is irradiated. An interferometer that forms a measurement optical path along a scanning direction of the reticle holder and obtains position information of the reticle holder;
A guide member for suppressing the gas from leaking to the measurement optical path side of the interferometer,
The exposure apparatus according to claim 1, further comprising:   The exposure apparatus according to claim 4, wherein the guide member is provided on the reticle holder. A measuring device for measuring using measuring light;
An isolation member for isolating the gas from at least a part of the optical path of the measurement light;
The exposure apparatus according to claim 1, further comprising:   The exposure apparatus according to claim 1, further comprising an ion supply device that supplies a gas containing ions into the first space and the second space.