JP2006017994A - Optical fiber cable sealing method and projection exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a metal bellows tube housing an optical fiber disposed in a vacuum environment from stretching or shrinking even when the pressure in the environment changes. <P>SOLUTION: The metal bellows tube housing an optical fiber has one or a plurality of wire members having higher rigidity than the optical fiber and having a length equivalent to that of the optical fiber, with the end face of the wire member fixed to the end face of a flange fabricated on the optical fiber and to the end face of the metal bellows. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for sealing an optical fiber cable in which outgassing does not occur even in an environment with pressure fluctuation, for example, an environment such as a vacuum environment of an exposure apparatus.

  With the miniaturization of the semiconductor structure, the projection exposure apparatus is required to further shorten the wavelength of the light source. Since these short-wavelength light sources do not transmit the normal atmospheric space, and in consideration of deterioration of mirrors used, for example, in an exposure apparatus using EUV (extreme short ultraviolet) light, the entire apparatus is in a vacuum environment. There is a need.

  In general, in order to introduce light into a device configured inside a vacuum environment, a method is adopted in which a light source is installed outside the vacuum environment and inserted into the vacuum environment using an optical fiber.

  When using optical fiber in a vacuum environment, degassing from the adhesive used in the optical fiber and the resin material that coats the optical fiber can contaminate the vacuum environment and cause the degree of vacuum to deteriorate. Such methods as using an adhesive with little degassing, forming the entire fiber in a metal pipe or a flexible pipe, and forming a metal coating on the optical fiber.

  Further, a structure has been proposed in which a flange-shaped connector is formed at the boundary of the vacuum environment, and the optical fiber is sealed and connected to keep the vacuum environment sealed.

  As a method for encapsulating an optical fiber in a flexible tube, Japanese Patent Application Laid-Open No. 2002-115054 discloses a configuration in which an optical fiber is enclosed in a flexible tube connected to a flange portion.

Further, regarding the configuration of the connector portion at the boundary with the vacuum environment, there is disclosed a connector in which a light transmitting material is configured and sealed with a vacuum sealing material as disclosed in JP-A-6-3561.
JP 2002-115054 A JP-A-6-3561

  Regarding flexible pipes, if a highly flexible metal bellows is used, it is easy to handle the optical fiber in the device, but the metal bellows expands and contracts due to pressure fluctuations in a vacuum environment. There is.

  Since stress is applied to the optical fiber formed inside due to the expansion and contraction of the metal bellows, there is a problem that the optical fiber is deteriorated or broken in the worst case.

  From the above viewpoint, in a method of sealing an optical fiber in a flexible tube, a metal pipe having low stretchability is used. However, when metal pipes with low stretchability are used, the minimum bending radius of the metal pipes is large, so that it is difficult to handle them in the apparatus.

  In recent years, a sealing structure that has sufficient flexibility and low elasticity by enclosing a fiber with a metal bellows having high elasticity and covering the outside with a metal net-like tube called a blade has been proposed.

  However, in a highly clean environment such as a semiconductor exposure apparatus, there is a problem that dust and dust are generated by rubbing the metal bellows and the blade.

  The object of the present invention is to configure one or more cables that are less stretchable than the optical fiber on both end faces of the metal bellows so that the metal bellows containing the optical fiber does not stretch due to pressure fluctuations in a vacuum environment. An object of the present invention is to provide an optical fiber sealing means in which stress applied to an optical fiber due to expansion and contraction of a metal bellows is suppressed.

  Or, even in a vacuum environment by using a metal bellows that does not degas even in a vacuum environment and is flexible and has a flexibility that is almost equal to or greater than the minimum bending radius of the optical fiber. In an optical fiber that facilitates handling of the optical fiber, the expansion and contraction of the metal bellows is suppressed by controlling the difference between the pressure in the vacuum environment where the optical fiber is arranged and the pressure inside the metal bellows, and stress is applied to the optical fiber. An object of the present invention is to provide an optical fiber sealing means having a structure that does not hang.

  In addition, by using the means for suppressing expansion and contraction of the metal bellows, light that suppresses stress from being applied to the optical fiber in the metal bellows due to expansion and contraction of the metal bellows due to pressure fluctuation in the vacuum environment. It is to provide a fiber sealing means.

  It is another object of the present invention to provide a projection exposure apparatus in which an optical fiber is used which is less degassed in a vacuum environment and does not contaminate the vacuum environment.

  In order to achieve the above object, the invention according to claims 1 and 2 of the present application is characterized in that the end face of the bellows is sealed with an optical fiber in a metal bellows having sufficient flexibility and introduced into the installation environment of the optical fiber. In order to suppress the application of tensile or compressive stress to the optical fiber due to the expansion and contraction of the bellows due to pressure fluctuations in the installation environment, which is fixed to the end face and has a flange-shaped sealing structure at the boundary with the installation environment. An end face of one or a plurality of wire-like members having a length equivalent to that of a highly rigid optical fiber is fixed to a flange end face and a metal bellows end face formed in the optical fiber.

  Further, in the first and third aspects of the invention, an optical fiber is sealed in the metal bellows, an end face to be introduced into the installation environment of the optical fiber is fixed to the end face of the bellows, and a flange-shaped portion is formed at a boundary portion with the installation environment. The shape is a sealed structure, and is sealed by the pressure inside the metal bellows and the metal bellows in order to suppress the tensile or compressive stress on the optical fiber due to the expansion and contraction of the bellows due to pressure fluctuations in the installation environment. In order to control the difference from the pressure of the installation environment in which the optical fiber is configured, a mechanism for controlling the pressure inside the metal bellows is provided at the flange portion provided at the boundary with the installation environment. .

  According to a fourth aspect of the present invention, an optical fiber is sealed in the metal bellows, and an end face to be introduced into the installation environment of the optical fiber is fixed to the end face of the bellows, and a flange-shaped sealing structure is provided at a boundary portion with the installation environment. One or a plurality of optical fibers having a length equivalent to that of an optical fiber having a rigidity higher than that of the optical fiber in order to suppress the tensile or compressive stress from being applied to the optical fiber due to the expansion and contraction of the bellows due to the pressure fluctuation of the installation environment. The end surface of the wire-like member is fixed to the flange end surface and the metal bellows end surface configured in the optical fiber, and the installation environment in which the pressure inside the metal bellows and the optical fiber sealed in the metal bellows is arranged and configured. In order to control the difference from the pressure, a mechanism for controlling the pressure inside the metal bellows is provided at the flange provided at the boundary with the installation environment. The features.

  According to the present invention, when an optical fiber is arranged and configured in a vacuum environment, the optical fiber is sealed in a vacuum metal bellows having sufficient flexibility, and the flange portion arranged and configured at the boundary with the vacuum environment and the vacuum By arranging a wire-like member on the flange part configured on the end face of the optical fiber inserted into the environment, the metal bellows is prevented from expanding and contracting due to pressure fluctuations in the vacuum environment, and tensile or compressive stress is applied to the optical fiber. It is possible to realize a structure in which no occurs.

  Further, according to the present invention, when an optical fiber is arranged and configured in a vacuum environment, the optical fiber is sealed with a sufficiently flexible metal bellows for vacuum, and the flange is arranged and configured at the boundary with the vacuum vacuum environment. A pipe for pressure adjustment is configured in the part, and the metal bellows is prevented from expanding and contracting due to pressure fluctuations in the vacuum environment by adjusting the pressure in the metal bellows by the solenoid valve, pressure control means and pressure adjustment means, and the optical fiber A structure in which no tensile or compressive stress is generated can be realized.

  From the above, when an optical fiber is introduced in a vacuum environment, an optical fiber having both sufficient flexibility and low degassing property can be arranged, which causes causes such as contamination of the vacuum environment and lowering of the vacuum degree. Can be removed.

  For this reason, the optical fiber shown in the present invention is used in a projection exposure apparatus constituted by a vacuum environment such as an EUV exposure apparatus, so that the contamination of the vacuum environment, the decrease in the degree of vacuum, and the fogging phenomenon of the lens do not occur. A projection exposure apparatus that can maintain high-precision optical performance over a long period of time can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is the best representation of the first embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the optical fiber shown in FIG. 1 as viewed from the end face outside the vacuum environment.

  In FIG. 1, an optical fiber 1 is formed of a coating protective layer 2 made of a flexible material such as resin, and a vacuum flange 3 is formed at the boundary with the vacuum environment, and the optical fiber is introduced into the vacuum environment.

  The vacuum flange and the optical fiber protective coating are sealed with a vacuum filler 4 or the like, and the seal with the wall 5 of the vacuum apparatus to which the vacuum flange is attached is sealed with a seal member such as an O-ring 6.

  A vacuum bellows 7 with high flexibility for sealing the optical fiber is welded and fixed to the surface of the vacuum flange on the vacuum environment side.

  Further, a metal flange 8 to which the vacuum bellows is welded and fixed is formed on the end face on the vacuum environment side of the optical fiber, and the optical fiber is sealed by the vacuum filler 4 and the window material 9.

  In addition, as a method for sealing with a window material, a configuration using a vacuum adhesive, a method of fixing a sealing member such as an O-ring with a metal member, and the like are conceivable, but not limited thereto.

  Here, both ends of the wire are fixed to the flange portion 8 formed on the vacuum environment side surface of the flange portion 3 provided at the boundary portion of the optical fiber with the vacuum environment and the end surface on the vacuum environment side of the optical fiber. A shaped member 10 is configured.

  In addition, although the said wire-shaped member is one arrangement structure in FIG. 1, you may arrange | position two or more.

  Accordingly, in FIG. 1, the left side of the boundary wall 5 between the vacuum environment and the atmospheric environment is the vacuum environment, but the expansion and contraction of the vacuum metal bellows with the fluctuation of the pressure in the vacuum environment is suppressed, and the optical fiber is pulled or stretched. It can prevent that compressive stress is applied.

  Therefore, it is possible to introduce desired light into the vacuum environment by connecting a light source not shown in the drawing to the attachment terminal 11 configured on the end face outside the vacuum environment of the optical fiber.

  FIG. 3 is the best representation of the second embodiment of the present invention.

  In FIG. 3, as in the first embodiment, the optical fiber 1 is made of a coating layer 2 made of a flexible material such as resin, and a vacuum flange 3 is formed at the boundary with the vacuum environment. An optical fiber is introduced.

  The vacuum flange and the optical fiber protective coating are sealed with a vacuum filler 4 or the like, and the seal with the wall 5 of the vacuum apparatus to which the vacuum flange is attached is sealed with a seal member such as an O-ring 6.

  A vacuum bellows 7 with high flexibility for sealing the optical fiber is welded and fixed to the surface of the vacuum flange on the vacuum environment side.

  Further, a metal flange 8 to which the vacuum bellows is welded and fixed is formed on the end face on the vacuum environment side of the optical fiber, and the optical fiber is sealed by the vacuum filler 4 and the window material 9.

  In addition, as a method for sealing with a window material, a configuration using a vacuum adhesive, a method of fixing a sealing member such as an O-ring with a metal member, and the like are conceivable, but not limited thereto.

  Here, a pressure adjusting pipe 12 is joined to a flange portion 3 provided at a boundary portion between the optical fiber and the vacuum environment.

  In FIG. 3, the pressure adjusting pipe is arranged at one place, but may be arranged at a plurality of places.

  The pressure adjusting pipe is connected to the pressure adjusting means 14 via an electromagnetic valve 13 controlled by the pressure control means.

  The pressure control means is not shown in the figure as well as the pressure in the vacuum environment measured from the vacuum environment pressure measurement means not shown in the figure, but from the pressure measurement means in the vacuum bellows sealed with the optical fiber. In order to control the difference in the measured pressure in the vacuum bellows, the pressure adjusting means exhausts or supplies air or an inert gas to the pressure adjusting pipe.

  Therefore, in FIG. 3, the left side of the boundary wall 5 between the vacuum environment and the atmospheric environment is the vacuum environment, but the bellows is adjusted by the pressure adjusting means so that the vacuum metal bellows does not expand and contract when the pressure fluctuation in the vacuum environment occurs. By adjusting the internal pressure, the metal bellows can be prevented from expanding and contracting, and a tensile or compressive stress can be prevented from being applied to the optical fiber.

  Therefore, it is possible to introduce desired light into the vacuum environment by connecting a light source not shown in the drawing to the attachment terminal 11 configured on the end face outside the vacuum environment of the optical fiber.

  FIG. 4 is the best representation of the third embodiment of the present invention.

  In FIG. 4, a vacuum flange 3 is formed at the boundary between the optical fiber 1 and the vacuum environment on the coating layer 2 formed of a flexible material such as a resin as in the first and second embodiments. An optical fiber is introduced in a vacuum environment.

  The vacuum flange and the optical fiber protective coating are sealed with a vacuum filler 4 or the like, and the seal with the wall 5 of the vacuum apparatus to which the vacuum flange is attached is sealed with a seal member such as an O-ring 6.

  A vacuum bellows 7 with high flexibility for sealing the optical fiber is welded and fixed to the surface of the vacuum flange on the vacuum environment side.

  Further, a metal flange 8 to which the vacuum bellows is welded and fixed is formed on the end face on the vacuum environment side of the optical fiber, and the optical fiber is sealed by the vacuum filler 4 and the window material 9.

  In addition, as a method for sealing with a window material, a configuration using a vacuum adhesive, a method of fixing a sealing member such as an O-ring with a metal member, and the like are conceivable, but not limited thereto.

  Here, the wire having both end surfaces fixed to the flange portion 8 formed on the vacuum environment side surface of the flange portion 3 and the end surface on the vacuum environment side of the optical fiber provided at the boundary portion between the optical fiber and the vacuum environment. A pressure adjusting pipe 12 is joined to the flange portion 3 provided at the boundary between the optical fiber and the vacuum environment of the optical fiber.

  In addition, although the said wire-shaped member and the piping for pressure adjustment are each arrange | positioned at 1 place in FIG. 4, you may arrange | position several places.

  The pressure adjusting pipe is connected to the pressure adjusting means 14 via an electromagnetic valve 13 controlled by the pressure control means.

  The pressure control means is not shown in the figure as well as the pressure in the vacuum environment measured from the vacuum environment pressure measurement means not shown in the figure, but from the pressure measurement means in the vacuum bellows sealed with the optical fiber. In order to control the difference in the measured pressure in the vacuum bellows, the pressure adjusting means exhausts or supplies air or an inert gas to the pressure adjusting pipe.

  Therefore, in FIG. 4, the left side of the boundary wall 5 between the vacuum environment and the atmospheric environment is a vacuum environment, but the wire-shaped member is arranged so that the vacuum metal bellows does not expand and contract when a pressure fluctuation in the vacuum environment occurs. In addition to suppressing the expansion and contraction of the bellows, the metal bellows can be prevented from expanding and contracting by adjusting the pressure inside the bellows by the pressure adjusting means, and the optical fiber is stretched or compressed by the effect that exceeds the first and second embodiments. It is possible to prevent stress from being applied.

  Therefore, it is possible to introduce desired light into the vacuum environment by connecting a light source not shown in the drawing to the attachment terminal 11 configured on the end face outside the vacuum environment of the optical fiber.

  FIG. 5 is the best representation of the fourth embodiment of the present invention. This embodiment shows a case where the present invention is applied particularly to a focus position detecting means of a projection exposure apparatus using a step-and-repeat method or a step-and-scan method for manufacturing devices.

  In the figure, R is a master so-called reticle (first object) to be projected, which is placed on the reticle stage 16 and is aligned and held with respect to the main body by an alignment system (not shown). The reticle R is illuminated with an illumination light beam IL from an illumination optical system (not shown). UL is a projection optical system, which is supported by a pedestal 23 and projects a pattern of the reticle R onto a wafer (photosensitive substrate) W.

  The wafer stage WS holding the wafer W is disposed in a vacuum chamber VC configured in the gantry 23 and the surface plate 24, and is placed on the wafer stage base 19, and the wafer W is projected onto the projection optical system UL. The XY stage 18 moves on the XY plane perpendicular to the optical axis, and the focus / leveling stage 17 placed on the XY stage 18. The focus / leveling stage 17 drives a wafer chuck (not shown) that sucks and holds the wafer W in the optical axis direction (Z direction) of the projection optical system UL, and drives the optical axis about the optical axis. Driving).

  An interferometer mirror 20 is fixed to the XY stage 18 and monitors the position in the X direction with a laser interferometer 21 supported on the lower surface of the pedestal 23. The interferometer mirror 20 and the laser interferometer 21 are similarly arranged in the Y direction. Using signals obtained from the interferometer mirror 20 and the laser interferometer 21, the wafer W is always positioned at a predetermined position by a control system (not shown) of the XY stage 18.

  In the stage space, the surface position detection device 22 is also fixed to the lower surface of the pedestal 23. This exposure device detects the height and inclination of the surface of the wafer W with respect to the projection optical system UL, and the detected value is a predetermined value. The exposure area of the wafer W is sent by sending a detection signal to a control means (not shown) of the focus / leveling stage 17 so that the best focus value (a predetermined command value indicating the height of the image plane of the projection optical system) is obtained. The height and inclination of the image are corrected and controlled.

These main components are installed in a vacuum thermostatic chamber VC. In the vacuum constant temperature chamber, the pressure is maintained at a degree of vacuum of about 10 ⁻⁴ Pa and temperature control is performed with higher accuracy than a normal clean room. For example, the temperature control of the clean room is ± 2 to 3 ° C. On the other hand, in the constant temperature chamber, it is kept at about ± 0.1 ° C.

  The light source BOX 35 in which the light source for the focal position measurement light beam that irradiates the wafer W with non-photosensitive light is a heat source unit, and thus is disposed outside the stage air-conditioning space. Illumination light i is emitted through an optical fiber 34, collected by an illumination system lens (not shown), and illuminates the focus detection pattern plate P, and includes a mirror 25, a relay lens (not shown), and an aperture stop (not shown). The pattern (aperture) is projected obliquely onto a plurality of measurement points located in the vicinity of or within the exposure area of the projection optical system UL via the irradiation objective lens 26 and the projection prism mirror 27 (not shown).

  The reflected light from the plurality of projected measurement points enters the light receiving optical system shown in FIG. 5, is collected by the light receiving prism mirror 28 and the condenser objective lens 29, and is reflected by the mirror 30 above the gantry 823. , Aperture stop (not shown), condensed by a relay lens system 31 inserted in a hole of the pedestal 23, reflected by the mirror 32 to the upper surface of the pedestal 23, and guided to a sensor unit composed of photoelectric detection means 33. Then, an image of the focus detection pattern (aperture) at each measurement point is re-imaged on the light receiving surface of the photoelectric detection means 33 corresponding to each measurement point. The photoelectric detection means 33 is a one-dimensional or two-dimensional CCD (charge coupled device), and detects the output signal by image processing, thereby corresponding to the amount of deviation caused by the height and tilt angle of the wafer W at each measurement point. A detection signal is generated.

  As described above, in the present embodiment, the light source unit 35 for the focus position measuring light beam, which is a heat generation source, cannot be configured in the vacuum temperature control chamber VC.

  Therefore, by using the optical fiber unit 34 shown in the present invention, illumination light emitted from the light source unit installed outside the vacuum space can be introduced into the vacuum space.

  At this time, even when the pressure in the vacuum constant temperature chamber fluctuates, the expansion or contraction of the bellows portion enclosing the optical fiber is suppressed, so that it is possible to prevent the optical fiber from being pulled or compressed.

  In the present embodiment, an example is shown in which the present invention is applied to a focus position detecting means in a projection exposure apparatus, but an apparatus for introducing light such as an off-axis scope for alignment in the projection exposure apparatus may be used.

Wire fixing View of the flange from the fiber end face Pressure adjustment Combined use Configuration example for projection exposure equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Optical fiber coating layer 3 Flange provided in vacuum environment boundary part 4 Vacuum filler 5 Vacuum environment boundary wall 6 O-ring 7 Vacuum metal bellows 8 Flange provided in optical fiber end 9 Window material 10 Wire-like member DESCRIPTION OF SYMBOLS 11 Optical fiber terminal provided in vacuum environment 12 Pressure adjustment piping 13 Electromagnetic valve 14 Pressure adjusting means 15 Fastening bolt 16 Reticle stage 17 Focus leveling stage 18 XY stage 19 Wafer stage base 20 Interferometer mirror 21 Laser interferometer 22 Focus position detector 23 Base 24 Surface plate 25 Mirror 26 Irradiation objective lens 27 Projection prism mirror 28 Light reception prism mirror 29 Condensing objective lens 30 Mirror 31 Relay lens 32 Mirror 33 Photoelectric detection means 34 Optical fiber unit 35 Light source unit 36 IL. Illumination beam R Reticle UL Projection optical system W Wafer WS Wafer stage i Focus position detection device Illumination light P Focus detection pattern plate VC Vacuum chamber

Claims (8)

  A method for sealing an optical fiber cable sealed with a flexible metal flexible pipe, wherein the tensile or compressive stress is applied to the optical fiber cable due to expansion and contraction of the flexible pipe due to pressure fluctuation outside the flexible pipe. A method for sealing an optical fiber cable, characterized by comprising means for suppressing the above.   The means for suppressing the expansion and contraction of the flexible tube is a member having a smaller expansion rate than the optical fiber cable and having sufficient flexibility, and is fixed and sealed to both end faces of the flexible tube, and is equivalent to the optical fiber cable. 2. The optical fiber cable sealing method according to claim 1, wherein the optical fiber cable is a linear member having a length.   2. The optical fiber cable sealing method according to claim 1, wherein the means for suppressing expansion and contraction of the flexible pipe is a pressure adjusting mechanism that controls a pressure difference between the pressure outside the flexible pipe and the pressure inside the flexible pipe. .   The method for sealing an optical fiber cable according to any one of claims 1 to 3, wherein the pressure fluctuation range is between atmospheric pressure and vacuum pressure. The method for sealing an optical fiber cable according to any one of claims 1 to 4, wherein the vacuum pressure is a pressure of 10 ^-1 Pa or less. The method for sealing an optical fiber cable according to any one of claims 1, 2, 4, and 5, wherein the linear member has a rigidity equal to or higher than a Young's modulus (7.9 × 10 ¹⁰ Pa) of glass.   The metal flexible tube having flexibility for sealing the optical fiber has a structure that does not generate a degassing component in an installation environment of the optical fiber. A method for sealing optical fiber cables.   A projection exposure apparatus comprising a metal flexible tube for sealing an optical fiber cable by the optical fiber cable sealing method according to claim 1.

Images