Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
  • G03F7/70566—Polarisation control
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J9/00—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength
  • G01J9/02—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength by interferometric methods
  • G01J9/0246—Measuring optical wavelength
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
  • G03F7/70575—Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
  • G03F7/70583—Speckle reduction, e.g. coherence control or amplitude/wavefront splitting
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
  • H01S3/08—Construction or shape of optical resonators or components thereof
  • H01S3/08004—Construction or shape of optical resonators or components thereof incorporating a dispersive element, e.g. a prism for wavelength selection
  • H01S3/08009—Construction or shape of optical resonators or components thereof incorporating a dispersive element, e.g. a prism for wavelength selection using a diffraction grating
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
  • H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
  • H01S3/139—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
  • H01S3/1394—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length by using an active reference, e.g. second laser, klystron or other standard frequency source
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
  • H01S3/22—Gases
  • H01S3/223—Gases the active gas being polyatomic, i.e. containing two or more atoms
  • H01S3/225—Gases the active gas being polyatomic, i.e. containing two or more atoms comprising an excimer or exciplex
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/0014—Monitoring arrangements not otherwise provided for
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
  • H01S3/08—Construction or shape of optical resonators or components thereof
  • H01S3/08004—Construction or shape of optical resonators or components thereof incorporating a dispersive element, e.g. a prism for wavelength selection

Definitions

• the present invention relates to a narrow-band oscillation excimer laser and a wavelength detector, and is particularly suitable for use as a light source for a reduction projection exposure apparatus for manufacturing semiconductor devices. . Background technology
• excimer lasers as light sources for reduction projection exposure apparatuses (hereinafter referred to as steppers) for manufacturing semiconductor devices. Because the wavelength of the excimer laser is short (KrF wavelength is about 248.4 nm), it is possible to extend the limit of light exposure to 0.5 m or less. If the resolution is the same as that of the mercury lamp, the depth of focus and the number of apertures (NA) of the lens will be deeper than the conventional mercury lamp g-line and i-line. It is possible to expect many excellent advantages, such as a small exposure area, a large exposure area, and a large power. .
• an excimer laser used as a light source for a stepper is required to have a narrow band with a line width of 3 pm or less, and a large force is required. Output power is required.
• the technique of excimer laser narrowing is the power that has been conventionally called the locking lock method.
• a wavelength selection element etalon, diffraction grating, prism, etc.
• the space mode is restricted by the hall, and this laser
• the output light of this type of base has a coherence property of ⁇ ⁇ , and the base that uses it as a light source for reduced exposure generates a super-saturated light. It is thought that the generation of the stickiness pattern depends on the number of spatial modes included in the laser light. In other words, it is easy to generate a speckle pattern in which the number of spatial transverse modes covered by the laser light is small, and conversely, the spatial mode is reduced.
• gap-gap etalon Another promising technique for narrowing the bandwidth of an excimer is to use a gap-gap etalon, which is a wavelength selective element.
• Conventional technology using a gap etalon is a technology developed by AT & T Bell Laboratories.
• An air gap etalon is placed between the front mirror and the laser chamber of the laser to reduce the bandwidth of the laser.
• a grating with comparatively excellent durability is adopted as a wavelength selection element, and the wavelength of the laser light is narrowed.
• excimer lasers that use this grating as a wavelength-selective element for which a Shima laser has been proposed, Position the pinhole in the resonator to reduce the angle of the beam in the resonator, or launch the beam into the grating.
• the laser light is expanded by a beam expander.
• the power of this beam extruder is that of using a prism beam extruder constructed using prism. " is there .
• the narrow-band oscillation excimer laser used for the stebber narrows the line width to 3 pm or less, as described above, and increases the bandwidth. Output is required.
• the enlargement ratio of the prism beam expander is reduced to reduce the line width. Need to be identified.
• the narrow laser excimer laser when used as the light source of the stebber, it is necessary to narrow the output laser light of the excimer laser. Therefore, it is necessary to stably control the wavelength of the narrowed output laser light with high accuracy.
• a monaural etalon power has been used to measure the wavelength line width of output light from a narrow-band oscillation excimer laser or to detect the wavelength.
• the monitor etalon is constructed using an air gap with a partial reflection mirror arranged opposite to it with a predetermined gap.
• the transmission wavelength of the air gap is expressed as follows.
• n the refractive index between the partial reflection mirrors
• S the normal to the eta-ron and the incident light. It is the angle formed by the optical axis.
• n, d, and m are constant, the wavelength changes. It can be understood that when it changes, it changes.
• the monitor etalon uses this property to detect the wavelength of the light to be detected, and in the above-mentioned monitor etalon, If the pressure in the gap and the ambient temperature change, the angle 0 described above will change even if the wave length is constant. Therefore, when using a monitor etalon, wavelength detection is performed by controlling the pressure and the ambient temperature in the air gap to a constant value.
• a reference light whose wavelength is known in advance is input to the monitor etalon together with the light to be detected, and the relative value of the detected light with respect to this reference light is input.
• a device for detecting the absolute wavelength of the detected light by detecting the wavelength There has been proposed a device for detecting the absolute wavelength of the detected light by detecting the wavelength.
• the transmitted light from the monitor etalon should be directly incident on the detection surface of a photodetector such as a CCD image sensor. ing .
• this device Since this device is designed so that the output of the monitor etalon is directly incident on the photodetector, the detected light and the reference light can be sufficiently separated. A large amount of light cannot enter the photodetector, causing inconveniences such as no interference fringes on the photodetector.
• the purpose of the present invention is to provide an excimer laser using a brilliance beam extruder and a grating as a narrowing element.
• -A narrow-band oscillation excimer laser that does not increase loss even if the enlargement rate of the prism beam expander is increased. It must be provided.
• Another object of the present invention is to allow the reference light and the light to be detected to enter the photodetector with sufficient amounts of light, respectively.
• An object of the present invention is to provide a narrow-band oscillation excimer laser wavelength detector capable of detecting each interference fringe with high accuracy. Opening of the light
• the drawing direction of the grating and the bliss beam are provided.
• the beam expansion direction of the spreader is almost the same as that of the prism beam, the linearly polarized wave almost parallel to the beam expansion direction of the prism beam expander.
• selective oscillation means for selectively oscillating is provided.
• the selective oscillating means can be constituted by a light emitting element arranged in the optical resonator.
• the selective oscillating means is substantially in the direction of the beam expansion direction of the prism pad and in the plane of the laser optical axis with respect to the laser optical axis. It can be configured to include the front or rear window of the laser chamber arranged so as to form a star angle.
• the selective oscillating means is the prism beam exciter. Of the polarization component almost parallel to the beam expansion direction of the The prism beam exciton, which selectively prevents reflection of light. It can be constructed by including an anti-reflection film coated on one side of the prism that constitutes the solder
• prism beam exno By selectively oscillating a linearly polarized wave that is almost parallel to the beam expansion direction of the beam, the angle of incidence on the prism increases and the prism increases. The loss can be reduced even if the number of increases. This is because a linearly polarized wave parallel to the beam expansion direction of the beam expander has a large transmittance even if the prism incident angle is large. It is. In addition, a large output can be obtained even with a narrower spectral line width.
• the wavelength detector of the narrow-band oscillation excimer laser according to the present invention, the reference light generated from the reference light source and the light to be detected are incident on the etalon.
• light detecting means for detecting interference fringes of the light condensed.
• drawings 1 (a) and 1 (b) are a plan view and a side view showing one embodiment of a narrow-band oscillation excimer laser according to the present invention.
• 2 (a) and 2 (b) are a plan view and a side view showing another embodiment of the narrow-band oscillation excimer laser of the present invention.
• 3 (a) and 3 (b) are a plan view and a side view showing still another embodiment of the narrow-band oscillation excimer laser according to the present invention.
• FIG. 4 is a diagram showing an embodiment of a wavelength detecting device of the narrow-band oscillation excimer laser according to the present invention.
• FIG. 5 is a diagram showing another embodiment of the wavelength detecting device of the narrow-band oscillation excimer laser of the present invention using a converging mirror.
• FIG. 6 is a merging type optical fiber.
• FIG. 9 is a diagram showing another embodiment of the wavelength detection device of the gobo region oscillation excimer laser of the present invention using the present invention.
• FIG. 7 is a diagram showing another embodiment of the wavelength detector of the narrow-band oscillation excimer laser of the present invention using a lamp as the reference light.
• FIG. 8 is a diagram showing another embodiment of the wavelength detector of the narrow-band oscillation excimer laser according to the present invention using a lamp and an optical fiber.
• FIG. 9 is a diagram showing another embodiment of the wavelength detector of the narrow-band oscillation excimer laser of the present invention in which the shutter and the fin are introduced.
• FIG. 10 is a flow chart showing the main routine of wavelength detection j in the configuration of FIG.
• Fig. 11 shows an example of a reference light detection subroutine.
• FIG. 12 is a flowchart showing an example of a detected light detection subroutine.
• FIGS. 1 (a) and 1 (b) show an embodiment of the narrow-band oscillation excimer laser according to the present invention
• FIG. 1 (a) is a plan view thereof
• FIG. Figure (b) shows the side view.
• the narrow-band oscillation excimer laser of this embodiment has a front mirror 11 and a grating 6 having the functions of a rear mirror and a wavelength selection element. Between the laser chamber 3, the polarizing element 4 and the beam expander (prism beam expander). The rhythms 5a, 5b are arranged. In this case, an optical resonator is configured between the front mirror 1 and the grating 6.
• the laser channel ⁇ 3 is not shown because the laser gas containing KrF etc. is filled in such a way that it can be circulated, and the laser gas is excited. Discharge electrodes are placed. Further, windows 2a and 2b are arranged at both ends of the laser chamber 3 at predetermined angles.
• the grating 6 selects light of a specific wavelength by using light diffraction, and has a large number of grooves arranged in a certain direction. In this specification, this number of grooves and The direction at right angles is called the drawing direction.
• the grating 6 is to select light of a specific wavelength by changing the angle of the grating 6 with respect to the incident light in the plane including this drawing direction. can do . That is, the grating 6 transmits only a specific diffracted light corresponding to the angle of the grating with respect to the incident light in a predetermined direction (in this case, the incident light). In this direction), thereby performing a selection operation for light of a specific wavelength.
• the grating 6 is illuminated by the laser beam expanded by the prism beam expander.
• the polarizing element 4 selectively selects only the polarized waves that are almost parallel to the prism 5a, 5b force, and the beam expansion direction of the resulting prism beam expander. Through.
• the polarizing element 4 includes, for example, a polarizing prism, a blue light dispersion prism, and a glass prism using a birefringent material (crystal, calcite, etc.). scan board co Do Let 's you transmitting a predetermined polarization component in the blanking re-menu was or whether you place at is te angle glass la scan the substrate (quartz, C a F 2 or M g F 2 was) -It can be composed of things with tents.
• the apparatus shown in FIGS. 1 (a) and 1 (b) is a prism beam exhaust comprising prisms 5a and 5b.
• Linear deviation almost parallel to the beam expansion direction of the spanner It is selectively oscillated by light waves.
• a linearly polarized wave parallel to the beam expansion direction of the prism beam expander has a large transmittance even if the angle of incidence on the prism is large. Therefore, even if the enlargement rate of the beam expander is increased to reduce the line width of the spectrum, the loss does not increase so much. . In other words, it is possible to construct a narrow loss oscillation laser with low loss.
• FIGS. 2 (a) and 2 (b) show another embodiment of the present invention.
• FIG. 2 (b) is a plan view thereof
• FIG. 2 (b) is a side view thereof. It is.
• a specific linearly polarized wave is selected by the rear window 2b of the laser chamber 3.
• the rear side window 2b of the laser channel 3 has a prism 5a, 5b force, and a prism beam.
• the laser light axis should be almost zero at the laser beam optical axis.
• Both the window 2b and the front window ⁇ 2a may be arranged at a predetermined price at the evening angle, or the front window may be provided. Only window 2a may be placed at the blue evening angle.
• FIGS. 3 (a) and 3 (b) show another embodiment in addition to the present invention.
• FIG. 3 (a) is a plan view
• FIG. 3 (b) is a side view of the side view.
• the prisms 5a and 5b that make up the prism beam expander have polarization components parallel to the expansion direction of the prism beam expander. It is constituted by coating an antireflection film for selectively preventing reflection of only light.
• portions 5c and 5b indicated by dotted lines indicate the coating portion.
• the coating should be performed on at least one light-transmitting surface of at least one prism. In this case, even if the angle of incidence on the prism becomes large, it is possible to maintain a transmittance of 99% or more.
• FIG. 4 shows an embodiment of a gouge band oscillation excimer laser wavelength detecting apparatus according to the present invention.
• the output light La of the narrow-band oscillation excimer laser 1 ⁇ is used as the detection light
• the He-Ne laser is used as the reference light source 20.
• Lasers such as lasers or Ar lasers are used.
• the wavelength of the reference laser and the wavelength of the excimer laser light generated from the reference light source 2 ° are different.
• a part of the laser light La output from the narrow-band oscillation excimer laser 10 is sampled by the beam splitter 30. This sampling light is applied to the beam splitter 40.
• the reference light Lb output from the reference light source 20 is applied to the other surface of the beam splitter 40.
• the beam splitter 40 transmits a part of the sampling light La output from the beam splitter 30 and outputs the beam splitter. Further, a part of the reference light Lb output from the reference light source 20 is reflected, and thereby, the sampling light and the reference light are formed.
• the trapping light of the sampling light and the reference light synthesized by the beam splitter 40 forms the beam by the concave lens 50. After being spread, it is irradiated onto etalon 60.
• the etalon 60 is composed of two transparent plates 60 a and 60 b, the inner surfaces of which are partially reflected mirrors, and which is provided for the etalon 60.
• the transmitted wave length is different depending on the angle of the incident light. That is, the etalon 60 is provided with a two-wavelength reflective film to reflect both the reference light La and the excimer laser light La having different wavelengths.
• This condenser lens 70 is, for example, an achromatic lens with chromatic aberration correction, and passes through the achromatic condenser lens 70. The chromatic aberration is corrected.
• the light detector 80 is disposed at the focal point of the converging lens 70, so that the light passing through the converging lens 70 is converted to an optical position detector.
• the first interference fringe corresponding to the wavelength of the reference light and the second interference fringe corresponding to the wavelength of the test light are formed on the detection surface of the light detector 8 ⁇ . Form interference fringes.
• the photodetector 80 detects the first and second interference fringes, and based on the detection, determines the relative wavelength of the detected light with respect to the wavelength of the reference light. Detects the wavelength and detects the wavelength of the known reference light. Detects the absolute wavelength of the detected light based on the calculated relative wavelength
• the photodetector 8 °. is configured using a one-dimensional or two-dimensional image sensor, a diode array, or a PSD (POSIT ION SENSITIVE DETECTOR) as the photodetector 8 °. can do .
• the beam is incident on the etalon 60 and the transmitted light of the etalon 60 is condensed.
• the image is formed on the photodetector 80 by the lens 70, so that a sufficient amount of light is incident on the photodetector 80 ⁇ and both light Are formed satisfactorily.
• FIG. 5 shows another embodiment of the narrow-band oscillation excimer laser wavelength detecting apparatus according to the present invention.
• parts having the same functions are denoted by the same reference numerals for convenience of explanation.o
• a condensing mirror 90 such as a concave mirror or an off-axis parabolic mirror is used.
• the reference beam Lb and the excimer laser beam La are transmitted through the concave lens 50 to expand the beam, and are incident on the etalon 60.
• the transmitted light from the lamp 60 is reflected by the condensing mirror 90, and the reflected light is reflected on the detection surface of the photodetector 80 arranged at the focal position of the condensing mirror 90. Make it incident.
• the optical mirror 90 is a reflecting surface, there is no chromatic aberration at all, and this causes both interference fringes of the excimer laser light La and the reference laser light Lb to be reduced. It is possible to form an image on the photodetector 80 located at the same position, that is, at the focal position of the mirror 90 o
• the concave lens 50 and the condensing mirror 90 allow the interference fringes with a sufficient light amount as in the previous embodiment. Can be detected with high accuracy.
• FIG. 6 shows another embodiment in addition to the narrow-band oscillation excimer laser wavelength detector of the present invention.
• the excimer laser light La and the reference laser light Lb are synthesized by the merged optical fiber 4a.
• the excimer laser sampled at the beam splitter 30 is a condensing lens 11 and an optical fiber.
• the optical multiplexer:! 4 and the reference laser beam Lb generated from the reference light source 20 is a condensing lens 15, an optical fiber sleeve 16, and an optical fiber.
• the light is incident on the optical trap 14 through the bar 17.
• the optical multiplexer 14 multiplexes the two lights La and Lb, and the multiplexed light is incident on the optical fiber 18.
• the light power spread through the sleeve 19 is incident on the monitor etalon 60.
• the light transmitted through the monitor etalon 60 is formed on an optical detector 80 through an achromatic condensing lens 70.
• the position of the interference fringe is It does not depend on the position of the converging type optical fiber 10 and is determined only by the positional relationship between the etalon 60, the focusing lens 70, and the light detector 80.
• the adjustment work of the optical system is made easier by taking advantage of the advantages of the previous embodiment.
• chromatic aberration correction is performed by using the achromatic condensing lens 70, but this lens 70 is replaced.
• the concave mirror shown in Fig. 5 or the parabolic mirror 90 can be used instead.
• Fig. 7 shows another example of the narrow-band oscillation excimer laser wavelength detector of the present invention in which the lamp 20a, which is a surface light source, is used as the reference light source.
• the lamp 20a is, for example, a mercury lamp that generates reference light having a wavelength of 253.7 nm. That is, the excimer laser light La sampled by the beam splitter 30 is formed by the concave lens 21. After the beam is spread, it is incident on the beam splitter 40, and the beam splitter 40 emits the reference light L from the mercury lamp 20 at the beam splitter 40. After being formed with c, the etalon 60 is irradiated. The light transmitted through the etalon 60 is imaged on the photodetector 80 via the achromatic condensing lens 70.
• the chromatic aberration correction is performed by using the achromatic condensing lens 70, but this lens 70 Instead of using the concave mirror or the outer parabolic mirror 90 shown in Fig. 5 above, It is also good.
• FIG. 8 also shows another embodiment of the narrow-band oscillation excimer laser wavelength detecting apparatus of the present invention in which a mercury lamp 2a is used as a reference light source.
• the excimer laser light La is guided to the beam splitter 40 by using the optical fiber 23. are doing .
• the excimer laser light sampled by the beam splitter 3 ⁇ is shifted by the focusing lens 11 to the slave 2.
• the light is incident on the optical fiber 2, passes through the optical fiber 23, and is emitted through the sleeve 24.
• the light expanded by passing through the sleeve 24 is incident on the beam splitter 4 ° where the mercury lamp 2 ° is output.
• the etalon 60 is irradiated.
• the light transmitted through the aperture 60 is imaged on the photodetector 80 via the achromatic condensing lens 70.
• the concave mirror or the off-axis parabolic shown in FIG. 5 is used instead of the achromatic condensing lens 70.
• FIG. 9 shows another embodiment of the narrow-band oscillation excimer laser wavelength detecting apparatus according to the present invention.
• the achromatic condensing lens 70 is replaced with a condensing mirror 90 such as a concave mirror, an off-axis parabolic mirror, etc. It is designed to add notes 41 and shots 42 and 43.
• a filter 41 for selecting and outputting only a predetermined wavelength is provided between the shutter 42 and the beam splitter 40, and the filter 41 is provided for the filter 41.
• the reference light having a predetermined wavelength is incident on the beam splitter 4 °.
• the shutters 42 and 43 are provided to separately detect the reference light and the test light (excimer laser light). When detecting the reference light, open shutter 42 and close shutter 43. On the other hand, when detecting the light to be detected, the shutter 43 is opened and the shutter 42 is closed.
• the file 41 is arranged between the beam split 40 and the beam 42.
• the fins 41 may be inserted between the lamps 20a and 42.
• the filter 41 is used for beam scanning. It may be arranged at an appropriate position in the optical path from the splitter 40 to the optical detector 80.
• Fig. 1 shows the main routine for wavelength detection.
• the reference light detection subroutine is executed.
• Step 100 In this reference light detection subroutine, as shown in FIG. 11, the shutter 43 on the detected light side is closed and the shutter on the reference light side is closed. By opening the window 42, only the reference light Lc is incident on the photodetector 80 via the etalon 60 (step 20). 0, 210). Then, the radius Rs of the interference fringe of the reference light formed on the photodetector 80 is detected, and the radius Rs is stored (step 220).
• the timer value T of the timer is cleared to zero (step 110), and then the timer value T is reset.
• the radius Re obtained by the routine and the reference light subroutine are used.
• the absolute wavelength of the light to be detected is detected by comparing the obtained and stored radius R s (step 150). Thereafter, the processing of steps 140 and 150 is repeated until T> K.
• step 120 when ⁇ > ⁇ , the reference light detection subroutine shown in FIG. 11 was executed again, and the value obtained by the routine was obtained.
• the stored data R s is updated with the radius R s of the interference fringe of the reference light. Thereafter, the timer value T is cleared to zero, and then the detected light detection subroutine is executed again.
• the wavelengths of the reference light and the light to be detected are close to each other, it is difficult to detect both interference fringes simultaneously.
• the two are detected separately by the shutters 42 and 43, and the reference light is relatively stable, so the preset comparison is made.
• the interference fringes are detected at a predetermined long period K, and the light to be detected is always detected when the reference light is not detected. That is, in this case, the detection cycle of the reference light is set to be sufficiently longer than the detection cycle of the light to be detected.
• the radius of the interference fringe is detected, but the diameter or position of the interference fringe is detected to obtain the absolute wavelength of the light to be detected. You can do it.
• the amount of light to be detected may be increased by making parallel light incident on the etalon.
• the beam splitter 4 ⁇ receives the detection light on the transmission side and the reference light on the reflection side. Although they are arranged so that they are implemented, these relationships may be reversed. Also, this beam splitter 4 ⁇ uses a partial reflection mirror when the wavelengths of the reference light and the detection light are close to each other, and uses a dichroic mirror when the wavelength difference is large. It is recommended that you use each of the Ic mirrors.
• the configuration is made by using the air outlet, but instead of the air outlet, the solid ethanol is used instead of the air outlet.
• the same configuration can be achieved by using a component.
• the chromatic aberration of the focusing lens 70 is corrected, or the reference light and the light are covered by using the focusing mirror 90.
• the focusing lens 70 or the photodetector 80 is configured to be movable in the optical axis direction. Accordingly, the difference in the imaging position may be absorbed.
• the lens may be inserted between etalon 60 and photodetector 80.
• the laser beam La is expanded by the concave lens 50 or 21 to form the The force that makes it incident on 0; ', a convex lens is used in place of this concave lens, and after the light is condensed by the convex lens, the spread is increased.
• a diffusing plate for example, slip glass
• Industrial applications may be used in place of the concave lens 50.
• the drawing direction of the grating and the bristle beam extruder And the beam expansion direction of the beam is almost the same, and a linearly polarized wave that is almost parallel to the beam expansion direction of the prism beam expander is selectively emitted.
• the selective oscillation means for oscillating the loss in the prism beam expander can be almost eliminated. This makes it possible to narrow the spectral line width and obtain a large output.
• a simple condensing means can be provided behind the etalon.
• the configuration allows a sufficient amount of light to be incident on the photodetector, thereby ensuring that interference fringes are formed on the photodetector.
• the absolute wavelength of the detected light can be detected with high accuracy.
• an achromatic lens or a focusing mirror is used as a focusing means. This makes it possible to detect the absolute wavelength with high accuracy without making the optical system movable even if the reference light and the detection light have different wavelengths. .
• the wavelength detector of the narrow-band oscillation excimer laser and the narrow-band oscillation excimer laser according to the present invention is used as a light source of a reduction projection exposure apparatus for manufacturing semiconductor devices. It is suitable for adoption.

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• 1990
  • 1990-07-12 WO PCT/JP1990/000900 patent/WO1991001579A1/ja active Application Filing
  • 1990-07-12 DE DE19904091247 patent/DE4091247T1/de not_active Withdrawn
  • 1990-07-12 CA CA 2063600 patent/CA2063600A1/en not_active Abandoned

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