JP2007263897A - Calibration method and device for polarization meter, the polarization meter and exposure device equipped with the polarization meter, and measuring method of phase delay amount and wavelength plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration device which performs calibration of a polarization meter with high accuracy. <P>SOLUTION: The calibration device which performs calibration of the polarization meter 9 comprises a light source 21 which generates a linear polarized laser beam, a half-wave plate 24 which rotates the polarization direction of the laser beam, two polarization beam splitters 25A, 25B, and a polarization system 25 capable of rotation by a rotation mechanism 41. The rotation angle of the polarization system 25 is adjusted by the rotation mechanism 41, and the laser beam of a known polarization state which is emitted from the polarization system 25 is supplied to the polarization meter 9; and the known polarization state and the measured result of the polarization meter 9 are compared; and a parameter inside the polarization meter 9 is adjusted, according to the comparison results. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarization measurement technique for measuring the polarization state of incident light, an exposure technique using the polarization measurement technique, a calibration technique for the polarization measurement apparatus, and a phase lag amount of a wave plate used in the calibration of the polarization measurement apparatus. Related to measurement technology.

  For example, in a lithography process for manufacturing a semiconductor device, a pattern of a reticle (or a photomask) is transferred to each shot area of a wafer (or a glass plate, etc.) coated with a resist via a projection optical system. An exposure apparatus such as a stepper or a scanning stepper is used. In these exposure apparatuses, the exposure wavelength is gradually shortened in order to increase the resolution. At present, KrF excimer laser (wavelength 247 nm), ArF excimer laser (wavelength 193 nm), etc. are mainly used as illumination light for exposure. Excimer laser light is used.

  Recently, in order to further improve imaging performance such as resolution and depth of focus, polarization illumination using illumination light controlled to a predetermined polarization state has also been proposed. Since the excimer laser beam is almost linearly polarized when it is emitted from the light source, the polarization state can be easily controlled by rotating the polarization direction using a predetermined wave plate or the like in the illumination optical system, for example. .

  In order to use polarized illumination in the exposure apparatus, it is necessary to confirm whether or not the polarization state of the illumination light can actually be set to a target state. For this purpose, it is desirable to install a polarization measuring device on the wafer stage or the like of the exposure apparatus as necessary to measure the polarization state (polarization degree, etc.) of the illumination light. In this case, in order to improve the reliability of the measurement result of the polarization measuring device, it is desirable to calibrate the polarization measuring device periodically, for example.

Further, the polarization measuring device is provided with a wave plate (phase shift plate) such as a quarter wave plate, and the polarization state of incident light is calculated using the known retardation amount (phase delay amount) of the wave plate. There are types. In order to increase the measurement accuracy with this type of measurement device, it is necessary to measure the retardation amount of the wave plate with high accuracy.
In view of such a problem, an object of the present invention is to provide a calibration technique for increasing the measurement accuracy of a polarization measuring device.

Furthermore, an object of the present invention is to provide a measurement technique for measuring the phase lag amount of a wave plate used in a polarization measurement device or the like with high accuracy in order to increase the measurement accuracy of the polarization measurement device.
Another object of the present invention is to provide a polarization measuring apparatus calibrated by the calibration technique, an exposure apparatus equipped with the polarization measuring apparatus, and a wavelength plate measured by the phase delay measuring technique. .

  The polarization measuring device calibration method according to the present invention is a polarization measuring device (9) calibration method for measuring the polarization state of incident light. The polarization state is known to the polarization measuring device via at least one polarizer (25A). A first step of supplying the light beam, a second step of measuring the polarization state of the light beam with the polarization measuring device, and a third step of comparing the measurement result of the second step with the known polarization state of the light beam. It has. According to the present invention, the polarization measuring device can be calibrated by using a light beam whose polarization state is known.

  The polarization measuring device calibration apparatus according to the present invention includes a light source (21) that generates a light beam and at least one polarizer (25A) in the polarization measuring device (9) that measures the polarization state of incident light. And a polarization optical system (25) for setting the polarization state of the light beam generated from the light source to a predetermined state and supplying the polarization state to the polarization measuring device. According to the present invention, the calibration method of the polarimetry apparatus of the present invention can be used.

  The phase delay amount measuring method of the present invention is a polarization optical system (37) including a linearly polarized light beam including at least one polarizer (37A) in the method of measuring the phase delay amount of the optical element (35). A first step of causing the light beam and the polarization optical system to rotate relative to each other so that the output of the photoelectric detector is minimized or maximized, and the light beam is detected. A second step of determining the reference rotation angle of the optical element to be measured when the output of the photoelectric detector is minimized or maximized by entering the polarizing optical system via the optical element; The light beam is rotated by a predetermined angle with respect to the reference rotation angle, the light beam is supplied to the photoelectric detector through the optical element to be measured and the polarization optical system, and the output of the photoelectric detector is minimized or maximized. 3rd to obtain the rotation angle of the polarization optical system Degree and, in which a fourth step of obtaining the phase delay of the test optical element based on the rotation angle determined in the third step. According to the present invention, the amount of phase delay of the optical element to be measured can be measured with high accuracy.

  Next, the polarimetry apparatus according to the present invention is calibrated by the polarization measurement value calibration method of the present invention. An exposure apparatus according to the present invention illuminates a pattern (M) with an exposure beam, and in the exposure apparatus that transfers the pattern onto the photoreceptor (W) via the projection optical system (PL), the exposure beam is polarized. In order to measure the state, the calibrated polarization measuring device (9) of the present invention is provided. The wave plate according to the present invention is obtained by measuring the phase lag amount by the phase lag amount measuring method of the present invention.

  In addition, although the reference numerals in parentheses attached to the predetermined elements of the present invention correspond to members in the drawings showing an embodiment of the present invention, each reference numeral of the present invention is provided for easy understanding of the present invention. The elements are merely illustrative, and the present invention is not limited to the configuration of the embodiment.

Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of an exposure apparatus of this example. In FIG. 1, an ArF excimer laser light source (wavelength 193 nm) having a narrow oscillation wavelength is used as a light source 1 for exposure. Also, a KrF excimer laser light source (wavelength 247 nm), an F ₂ laser light source (wavelength 157 nm), or the like can be used. The illumination light IL (exposure beam) emitted from the light source 1 is a linearly polarized laser beam having a polarization degree V of, for example, 0.95 or more. The degree of polarization V is S ₀ indicating the total intensity of the light beam, S ₁ indicating the difference intensity obtained by subtracting the intensity of the linearly polarized light component in the vertical direction from the intensity of the linearly polarized light component in the horizontal direction, and inclined by 45 ° with respect to the horizontal direction. S ₂ indicating the difference intensity obtained by subtracting the intensity of the linearly polarized light component in the direction orthogonal to the intensity of the linearly polarized light component in the direction, and the difference obtained by subtracting the intensity of the counterclockwise circularly polarized light component from the intensity of the clockwise circularly polarized light component Using the Stokes parameters S _{0 to} S ₃ composed of S ₃ indicating the intensity, it can be expressed by the following equation.

V = (S ₁ ² + S ₂ ² + S ₃ ² ) ^1/2 / S ₀ (1)
The illumination light IL emitted from the light source 1 is incident on the polarization state variable unit 3 via the known beam transmission system 2. The polarization state varying unit 3 has a function of changing the polarization state of the illumination light IL with respect to a mask (or reticle) M, which will be described later, and consequently the wafer W. The polarization state variable unit 3 includes, as an example, a rotatable half-wave plate or quarter-wave plate, and sets the polarization direction of the illumination light IL to an arbitrary direction by rotating the half-wave plate. The illumination light IL can be made into circularly polarized light or elliptically polarized light by adjusting the rotation angle of the quarter wave plate used instead.

  The illumination light IL whose polarization state has been converted as necessary by the polarization state variable unit 3 passes through a beam shape variable unit 4 including a zoom optical system or the like for changing the cross-sectional shape of the light beam. (Or fly eye lens) 5. A surface light source including a large number of secondary light sources is formed on the exit surface (pupil surface of the illumination optical system) by a large number of micro lenses having positive refractive power constituting the micro fly's eye lens 5, and illumination light from the surface light source. By superimposing IL, the illuminance distribution of the illumination light IL is made uniform. Instead of the micro fly's eye lens 5, an optical integrator (homogenizer) such as a diffractive optical element or a rod integrator (internal reflection type integrator) may be used. A variable aperture stop (not shown) for switching and setting an aperture stop for various illumination methods such as normal illumination, annular illumination, dipole illumination, and modified illumination is provided on the pupil plane of the illumination optical system. Is installed.

  The illumination light IL emitted from the micro fly's eye lens 5 illuminates the mask blind 7 in which an opening for defining the shape of the illumination area on the mask M is formed via the condenser optical system 6. The illumination light IL that has passed through the opening of the mask blind 7 illuminates the mask M on which the transfer pattern is formed with a uniform illuminance distribution via the imaging optical system 8 and the optical path bending mirror. The illumination optical system includes members from the beam transmission system 2 to the imaging optical system 8. The operations of the light source 1, the polarization state varying unit 3, and the beam shape varying unit 4 are controlled by a main control system 11 that is composed of a computer and controls the overall operation of the apparatus. Further, for example, illumination light branched by a beam splitter (not shown) disposed between the micro fly's eye lens 5 and the condenser optical system 6 is received by an integrator sensor 10 including a photoelectric detector, and detected by the integrator sensor 10. A signal is supplied to the main control system 11. The main control system 11 controls the amount of illumination light IL based on the detection signal.

  Under the illumination light IL, the pattern of the mask M is transferred and exposed onto a wafer W (photosensitive member) coated with a resist via the projection optical system PL. Mask M is held on a mask stage (not shown), wafer W is held on wafer stage WST, and wafer stage WST is continuously moved and stepped in a plane perpendicular to optical axis AX of projection optical system PL on wafer base WB. Move. Further, the wafer stage WST has a focus position (in the optical axis AX direction) of the wafer W in order to focus the surface of the wafer W on the image plane of the projection optical system PL based on a measurement value of an autofocus sensor (not shown). And a focus / leveling stage that controls the tilt angle.

  At the time of exposure, the mask M and the wafer W are aligned by an alignment system (not shown) under the control of the main control system 11, and then the polarization state of the illumination light IL is set to a predetermined state by the polarization state variable unit 3. Is done. Thereafter, light emission of the light source 1 is started, and an operation of transferring the pattern of the mask M to one shot area on the wafer W through the projection optical system PL by a batch exposure method or a scanning exposure method, and light emission of the light source 1 are performed. The pattern of the mask M is transferred to all the shot areas on the wafer W by repeating the operation of stopping and stepping the wafer W. When the exposure apparatus of this example is an immersion type as shown in the pamphlet of International Publication No. 99/49504, pure water or the like is provided between the projection optical system PL and the wafer W from a liquid supply mechanism (not shown). Liquid is supplied.

Now, in the case of using polarized illumination in this way, in order to measure whether or not the polarization state of the illumination light IL is set to a target state, the polarization measurement device 9 is detachably attached to the wafer stage WST as an example. Is provided. The polarization measuring device 9 may be installed on a mask stage (not shown) to measure the polarization state of the illumination light IL from the illumination optical system. When measuring the polarization state of the illumination light IL via the projection optical system PL, the incident surface of the polarization measuring device 9 is moved to the exposure area of the projection optical system PL by driving the wafer stage WST.
The polarization measuring device 9 may be permanently installed on the wafer stage WST. Alternatively, for example, in the case where a measurement stage provided with a reference mark for alignment and a measurement unit for measuring the imaging characteristics of the projection optical system PL separately from the wafer stage WST, the measurement stage is arranged. Alternatively, the polarization measuring device 9 may be fixed.

  2 shows the configuration of the polarization measuring device 9 of FIG. 1. In FIG. 2, the illumination light IL is a pin of the pinhole member 90 when measuring the polarization state of the illumination light IL from the projection optical system PL of FIG. Pass through the hole 90a. The illumination light IL that has passed through the pinhole 90a is converted into a substantially parallel light beam through the collimator lens 91, reflected by the mirror 92, and then the relay lens system 93, the quarter wavelength plate 94 (phase shifter), and the polarization. The light is incident on a detection surface 96 a of an image sensor 96 made of a two-dimensional CCD via a beam splitter (hereinafter referred to as PBS) 95. The quarter-wave plate 94 can be rotated around the optical axis by the drive unit 97. The PBS 95 constitutes a polarizer for selectively transmitting a predetermined polarization component (here, P polarization component). The polarization measuring device 9 is configured to include members from the pinhole member 90 to the image sensor 96.

Information on the rotation angle of the quarter-wave plate 94 from the drive unit 97 and the detection signal (light quantity distribution information) of the image sensor 96 are supplied to the measurement unit 98. The measuring unit 98 obtains Stokes parameters S _{0 to} S ₃ indicating the polarization state of the illumination light IL by, for example, the rotational phase shift method based on the information about the rotation angle and the light amount distribution information, and the measurement result is obtained from the main control system. 11 is supplied. The Rotational Transition Phase Method is described in detail in, for example, Tsuruta: Optical Pencil-Applied Optics for Optical Engineers (New Technology Communications Co., Ltd.). Specifically, the measured value of the retardation amount (phase delay amount) of the slow axis illumination light with respect to the fast axis of the quarter-wave plate 94 is Γ, and the P-polarized illumination incident on one pixel of the image sensor 96 Assume that the measured value of the transmittance (parallel transmittance) of the PBS 95 related to light is tx, and the measured value of the transmittance (vertical transmittance) of the PBS 95 related to the S-polarized illumination light incident on the pixel is ty. In this case, the parallel transmittance tx is about 0.9, and the vertical transmittance ty is about 0.01. Further, among the Stokes parameters, the parameter S ₀ to 1/4 a _0/2 0 order coefficient when the Fourier transform with respect to the rotation angle θ of the wave plate 94 showing the total intensity, b ₂ coefficients of sin2θ, cos4θ Is a ₄ and the coefficient of sin 4θ is b ₄ .

At this time, when the coefficients A (= (tx ² + ty ² ) / 2) and B (= (tx ² −ty ² ) / 2) are used, the measured values of the Stokes parameters S _{0 to} S ₃ of the illumination light IL are as follows. become that way. By substituting this measurement value into equation (1), the degree of polarization V as the polarization state of the illumination light IL can be obtained. Information on the degree of polarization V is supplied from the measuring unit 98 to the main control system 11. The Stokes parameters S _{0 to} S ₃ themselves may be regarded as the polarization state and supplied to the main control system 11.

  As can be seen from the calculation formula of the degree of polarization V, the parameters affecting the measurement result of the degree of polarization V are the retardation amount Γ of the quarter-wave plate 94 (phase shifter) and the fast axis of the quarter-wave plate 94. Direction (rotational orientation), parallel transmittance tx and vertical transmittance ty of PBS 95, and rotational orientation of PBS 95 (for example, a rotational angle of a plane including incident light and a light beam reflected by the beam splitter surface), and polarization measurement. The correction target at the time of calibration of the device 9 is the values of these parameters.

Next, an example of a method for calibrating the measurement value of the polarization measuring device 9 will be described. Note that the calibration method of this example can also be used for calibration of polarization measuring devices other than the rotational phase shifter method.
FIG. 3 shows an example of a calibration device (calibration device) of the polarization measuring device 9. In FIG. 3, the calibration device includes a light source 21 having the same oscillation wavelength as the light source 1 of the exposure apparatus of FIG. Therefore, if the light source 1 is an ArF excimer laser light source, the light source 21 is also an ArF excimer laser light source. For this reason, the polarization measuring device 9 can be calibrated in the same state as when it is mounted on the exposure apparatus of FIG. However, the light source 21 and the light source 1 may have different oscillation wavelengths, and the light source 21 may be a light source other than the laser light source. The light source 21 emits a laser beam LB composed of a linearly polarized light beam having a polarization degree of 0.95 or more.

  The polarization direction of the laser beam LB emitted from the light source 21 is rotated through a beam splitter 22 having a high transmittance and a half-wave plate 24 held by a rotation mechanism (not shown), and the beam splitter surfaces are parallel to each other. Is incident on a polarization system 25 composed of two PBSs (polarization beam splitters) 25A and 25B arranged in series. The polarization system 25 is rotatably held around the optical axis by a rotating mechanism 41 including a fixing member 41b fixed to a column (not shown) and a rotating member 41a rotatably accommodated in the fixing member 41b. The laser beam transmitted through the polarization system 25 enters the polarization measuring device 9. Among the light beams incident on the polarization system 25, the P-polarized component with respect to the beam splitter surfaces of the PBSs 25 </ b> A and 25 </ b> B passes through the polarization system 25. By arranging the two PBSs 25A and 25B in series, the degree of polarization of the light beam transmitted through the polarization system 25 can be increased, and the polarization measuring device 9 can be calibrated with higher accuracy. However, when the measurement accuracy required by the polarization measuring device 9 is low, the polarization system 25 may be configured by only one PBS 25A. Conversely, when it is desired to increase the measurement accuracy, three or more PBSs may be arranged in series. Further, other polarizers such as a polarizing plate may be used instead of the PBSs 25A and 25B.

  On the other hand, the laser beam reflected (branched) by the beam splitter 22 is received by a light amount monitor 23 such as a photodiode. By controlling the output of the light source 21 so that the detection result of the light amount monitor 23 becomes a predetermined level, a laser beam having a substantially constant light amount can be incident on the polarization measuring device 9. A calibration apparatus is configured including the light source 1, the beam splitter 22, the light amount monitor 23, the half-wave plate 24, and the polarization system 25.

As an example, the polarization measuring device 9 is calibrated as follows using the calibration device of FIG.
First step: The rotation angle of the polarization system 25 is set to a predetermined angle by the rotation mechanism 41. Specifically, assuming that the optical axis of the laser beam LB emitted from the light source 21 is parallel to the horizontal plane, the polarization direction of the laser beam LB transmitted through the polarization system 25 is inclined 45 ° from the horizontal, vertical, and horizontal directions. The rotation angle of the polarization system 25 is set so as to be a direction or a direction inclined by 135 ° from the horizontal direction. Thereafter, the laser beam LB from the light source 21 is supplied to the polarization measuring device 9 via the beam splitter 22, the half-wave plate 24, and the polarization system 25. In this case, since the laser beam supplied to the polarization measuring device 9 is linearly polarized light whose polarization direction is known, the degree of polarization V1 can be obtained from the equation (1).

Second step: The polarization measuring device 9 measures the polarization degree V1 ′ of the supplied laser beam.
Third step: The degree of polarization V1 ′ of the laser beam measured by the polarization measuring device 9 is compared with the known degree of polarization V1 of the laser beam supplied to the polarization measuring device 9 in the first step, and the difference Δ1 Ask for. Next, any one of the retardation amount Γ of the quarter-wave plate 94 in FIG. 2, which is a parameter of the polarization measuring device 9, and the parallel transmittance tx and the vertical transmittance ty of the PBS 95 so as to reduce the difference Δ1. Correct the value of. Thereby, the calibration of the polarization measuring device 9 is completed.

Fourth step: In the measurement unit 98 (see FIG. 2) of the polarization measuring device 9, the measurement result of the polarization measuring device 9 can be corrected by recalculating the degree of polarization V1 ′ using the corrected parameters. .
Since there are five or more parameters to be corrected, the rotation angle of the polarization system 25 is set to five or more positions, and the first step and the second step described above are executed, respectively, and the polarization degree differences Δ1 to Δ5. In the third step, the retardation value Γ and the transmittances tx and ty may be corrected by the least square method or the like so that the differences Δ1 to Δ5 are reduced as a whole. Alternatively, a quarter wavelength plate may be installed on the exit surface of the polarization system 25 to supply a circularly polarized light beam to the polarization measuring device 9. As a result, the calibration accuracy of the polarization measuring device 9 can be increased.

As described above, according to the calibration device of this example, the measurement result of the polarization measuring device 9 can be calibrated by supplying the polarization measuring device 9 with the laser beam whose polarization state is known. The polarization measuring device 9 attached to the exposure apparatus in FIG. 1 is calibrated as described above.
If the output of the light source 1 is stable, the beam splitter 22 and the light amount monitor 23 may be omitted. Further, by using the half-wave plate 24 to make the polarization state of the laser beam LB incident on the polarization system 25 substantially P-polarized light, the utilization efficiency of the laser beam LB can be maintained high. If the utilization efficiency of the laser beam LB may be somewhat reduced, the half-wave plate 24 may be omitted. As the light source 21, a light source that emits a circularly polarized light or a randomly polarized light beam can be used. In this case, the half-wave plate 24 can be omitted. Further, when a circularly polarized light beam is supplied to the polarization measuring device 9, a ¼ wavelength plate may be disposed between the polarization system 25 and the polarization measuring device 9.

  In order to calibrate the polarization measuring device 9 for measuring the polarization state of the illumination light IL that has passed through the projection optical system PL as in the example of FIG. 1, as shown in FIG. An objective lens system 27 including lenses 27 a and 27 b may be disposed between the polarization measuring device 9. Further, in order to supply a circularly polarized light beam to the polarization measuring device 9, a quarter wavelength plate 28 may be disposed on the exit surface of the polarization system 25 as indicated by a dotted line.

  In FIG. 4 in which parts corresponding to those in FIG. 3 are assigned the same reference numerals, the laser beam LB transmitted through the polarization system 25 is supplied to the polarization measuring device 9 via the diffractive optical element 26 and the objective lens system 27. In this case, the objective lens system 27 is configured using a lens with extremely small retardation. In order to reduce the coherence of the laser beam LB on the pupil plane of the objective lens system 27, the diffractive optical element 26 is used. FIG. 5 shows an optical path from the diffractive optical element 26 to the polarization measuring device 9 in FIG. 4. In FIG. 5, the laser beam LB is diffracted by the diffractive optical element 26 in at least three directions. On the pupil plane, since three or more lights from different portions on the diffractive optical element 26 gather, the coherence decreases. The diffractive optical element 26 can be omitted.

  In the example of FIG. 4, a cover member 47 is provided so as to seal a space between the lens 27 b and the polarization measuring device 9, and the inside of the cover member 47 is connected from the liquid supply device 46 via a pipe 48. When performing immersion exposure with one exposure apparatus, the same liquid as that supplied between the projection optical system PL and the wafer W can be supplied. In this example, by supplying the liquid between the lens 27b and the polarization measuring device 9, the polarization measuring device 9 can be calibrated under the same conditions as in immersion exposure.

In the example of FIG. 4, the diffractive optical element 26 is used to reduce the coherence of the laser beam LB. However, as shown in FIG. 6, an optical integrator may be used to suppress the coherence. .
In FIG. 6, the laser beam LB emitted from the light source 21 is incident on the fly-eye lens 29, and the light beam emitted from the fly-eye lens 29 is condensed by the collimator lens 30 and irradiated to the first pinhole plate 31. Then, the light beam that has passed through the pinhole 31 a of the pinhole plate 31 is irradiated to the second pinhole plate 32. In place of the fly-eye lens 29, another optical integrator (homogenizer) such as a diffractive optical element may be used. The light beam that has passed through the pinhole 32a of the pinhole plate 32 is enlarged in cross-section by the beam expander 34 through the mirror 33 and the beam splitter 22, and then the half-wave plate 24, the polarization system 25, and the objective lens. The light enters the polarization measuring device 9 through the system 27. Further, the light beam branched by the beam splitter 22 is received by the light amount monitor 23.

In the calibration device of FIG. 6, a light beam obtained by superimposing light beams from a large number of microlenses constituting the fly-eye lens 29 is taken out via the pinhole plates 31 and 32, and the polarization state of the light beam with a larger cross-sectional shape of this light beam is obtained. Controlled and supplied to the polarization measuring device 9. Therefore, the influence of the coherence of the laser beam LB can be reduced and the polarization measuring device 9 can be calibrated with high accuracy.
Next, another example of the embodiment of the present invention will be described with reference to FIGS. In the above embodiment, the measurement value of the polarization measuring device 9 in FIG. 2 is calibrated by entering a light beam whose polarization state is known. In this example, in order to increase the measurement accuracy of the polarization measuring device 9, It is assumed that the retardation amount (phase delay amount) of the quarter wavelength plate 94 in FIG.

  FIG. 7A shows the retardation amount measuring apparatus of this example. In FIG. 7A in which parts corresponding to those in FIG. 3 are given the same reference numerals, the laser beam LB from the light source 21 is a beam splitter. 22 and the half-wave plate 24 and the light source side polarization system 25 to enter the test optical element 35. An example of the test optical element 35 is the quarter-wave plate 94 in FIG. The laser beam LB transmitted through the optical element 35 to be measured is formed by arranging two PBSs (polarized beam splitters) 37A and 37B in series so that the beam splitter surfaces are parallel through a quarter-wave plate 36 for measurement. Light is received by a photoelectric sensor 38 such as a photodiode via a measurement polarization system 37, and a detection signal of the photoelectric sensor 38 is supplied to a signal processing system 43. Note that the polarization system 37 may also be composed of only one PBS 37A, or may be composed of another polarizer such as a polarizing plate.

  The test optical element 35, the quarter-wave plate 36, and the polarization system 37 are supported by rotating mechanisms 42A, 42B, and 42C for rotating these members around the optical axis. Further, the test optical element 35 and the quarter wavelength plate 36 are configured to be retracted outside the optical path of the laser beam LB as required by an XY stage (not shown). Information on the rotation angles of the rotation mechanisms 42A, 42B, and 42C is also supplied to the signal processing system 43.

An example of an operation for measuring the retardation amount of the optical element 35 to be measured by the measurement apparatus of FIG.
First step: With the test optical element 35 and the quarter-wave plate 36 retracted outside the optical path, the light source 21 is caused to emit light, and the half-wave plate 24 is rotated to approximately P with respect to the polarization system 25. The polarized laser beam LB is supplied to the polarization system 25. As a result, a linearly polarized (P-polarized) laser beam LB having a large amount of light and a high degree of polarization is supplied from the polarization system 25 to the polarization system 37. In this state, the rotation angle of the polarization system 37 (via the rotation mechanism 42C) so that the incident laser beam LB becomes S-polarized light with respect to the polarization system 37, that is, the detection signal of the photoelectric sensor 38 is minimized. The relative rotation angle with respect to the laser beam LB) is set. Note that the rotation angle of the polarization system 37 can also be set so that the incident laser beam LB is P-polarized with respect to the polarization system 37, that is, the detection signal of the photoelectric sensor 38 is maximized ( The same applies below). It is also possible to rotate the light source 21 (laser beam LB) side.

Second step: The quarter-wave plate 36 is installed on the optical path so that the fast axis of the quarter-wave plate 36 is parallel to the polarization direction of the incident laser beam LB, that is, the detection by the photoelectric sensor 38. The rotation angle of the quarter wavelength plate 36 is set by the rotation mechanism 42B so that the signal is minimized.
Next, the test optical element 35 is placed on the optical path, and one crystal axis (for example, the fast axis) of the test optical element 35 is parallel to the polarization direction of the incident laser beam LB, that is, photoelectric. The rotation angle (reference rotation angle) of the test optical element 35 when the detection signal of the sensor 38 is minimized is obtained.

Third step: In a state in which the optical element 35 to be tested is rotated by 45 ° with respect to the reference rotation angle, the polarization direction of the laser beam LB transmitted through the quarter wavelength plate 36 is S-polarized (quenched) with respect to the polarization system 37 The rotation angle of the polarization system 37 when the detection signal of the photoelectric sensor 38 is minimized.
Fourth step: The retardation amount of the test optical element 35 can be obtained by doubling the rotation angle of the polarization system 37 obtained in the third step.

  That is, as shown in FIG. 7B, the fast axis 35a of the test optical element 35 is rotated by 45 ° with respect to the polarization direction 44 of the incident laser beam. Further, as shown in FIG. 7C, since the direction of the fast axis 36a of the quarter wavelength plate 36 is parallel to the polarization direction 44, if the retardation amount of the test optical element 35 is δ, 1 The polarization direction of the laser beam after passing through the / 4 wavelength plate 36 rotates by δ / 2 with respect to the direction of the fast axis 36a. Since this angle δ / 2 is the rotation angle of the polarization system 37 detected in the third step, the retardation amount δ can be obtained with high accuracy by the Senarmon method by doubling it.

The quarter-wave plate 94 of FIG. 2 is arranged as the optical element 35 to be tested, and the quarter-wave plate 94 in which the retardation amount is measured with high accuracy in the above-described process is placed in the polarization measuring device 9 of FIG. By using it, the measurement accuracy of the polarization degree of the polarization measuring device 9 is improved.
The rotation angle of the optical element 35 to be tested in the third step may be a predetermined angle other than 45 °. However, in this case, the conversion coefficient between the rotation angle of the polarization system 37 and the retardation amount δ of the optical element 35 to be obtained in the third step becomes a complex value different from 2.

  Further, for example, in the first step and the third step, in order to accurately obtain the transmittance (transmitted light amount) of the polarization system 37 from the detection signal of the photoelectric sensor 38, the polarization system 37 is configured as shown in FIG. The relationship between the rotation angle (PBS angle) θ (deg) of the PBS 37A (or 37B) and the transmittance t (θ) of the linearly polarized light beam may be measured and stored in advance. In this case, using a function f (θ) that changes linearly with respect to the rotation angle θ of the polarization system 37, f (θ) / t (θ) is used as a detection signal of the photoelectric sensor 38 according to the rotation angle θ. Multiplication enables linearity correction. In other words, the transmittance of the polarization system 37 can be obtained with high accuracy from the detection signal of the photoelectric sensor 38, particularly in a range where the rotation angle θ is small, and as a result, the rotation when the amount of light transmitted through the polarization system 37 is minimized. The corner can be determined efficiently.

Note that the transmittance characteristics of FIG. 8 can also be used when measuring the horizontal transmittance and the vertical transmittance of the PBS 95 of FIG. 2, thereby improving the measurement accuracy of the transmittance of the PBS 95, and thus The measurement accuracy of the polarization measuring device 9 is improved.
Further, when a semiconductor device is manufactured using the exposure apparatus of the above-described embodiment, the semiconductor device includes a step of designing a function and performance of the device, a step of manufacturing a reticle based on this step, and a wafer from a silicon material. Forming, aligning with the projection exposure apparatus of the above embodiment to expose the pattern of the reticle onto the wafer, forming a circuit pattern such as etching, device assembly step (dicing process, bonding process, packaging process) Including) and an inspection step.

  The present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device. For example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, The present invention can also be widely applied to various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip, and an exposure apparatus for manufacturing a mask itself. As described above, the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be taken without departing from the gist of the present invention.

  By using the polarization measuring device calibrated according to the present invention, the polarization state of the exposure beam during polarized illumination of the exposure device can be measured with high accuracy. Therefore, it becomes possible to perform polarized illumination with high accuracy based on the result, and a fine pattern can be manufactured with high accuracy.

It is a figure which shows schematic structure of the exposure apparatus of an example of embodiment of this invention. It is a figure which shows the structure of the polarimetry apparatus 9 in FIG. It is a figure which shows an example of the calibration apparatus of the polarization measuring device. It is a figure which shows the modification of the calibration apparatus of FIG. It is explanatory drawing of an effect | action of the diffractive optical element 26 in FIG. It is a figure which shows another modification of the calibration apparatus of FIG. (A) is a figure which shows an example of the measuring device of retardation amount, (B) is a figure which shows the test optical element 35, (C) is a figure which shows the quarter wavelength plate 36. It is a figure which shows an example of the relationship between the rotation angle of a polarizing beam splitter, and the transmittance | permeability.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 ... Polarization measuring apparatus, 94 ... 1/4 wavelength plate, 95 ... Polarization beam splitter, 21 ... Light source, 24 ... 1/2 wavelength plate, 25 ... Polarization system, 25A, 25B ... Polarization beam splitter, 26 ... Diffractive optical element 27 ... Objective lens system, 35 ... Optical element to be tested, 36 ... 1/4 wavelength plate, 37 ... Polarization system for measurement, 41 ... Rotation mechanism

Claims (13)

In a calibration method of a polarization measuring device that measures the polarization state of incident light,
A first step of supplying a light beam having a known polarization state via at least one polarizer to the polarization measuring device;
A second step of measuring the polarization state of the luminous flux with the polarization measuring device;
A calibration method for a polarization measuring device, comprising: a third step of comparing a measurement result of the second step with a known polarization state of the light beam.   The method of calibrating a polarization measuring device according to claim 1, further comprising a fourth step of calibrating the polarization measuring device according to a comparison result of the third step.   A polarization measuring device calibrated by the polarization measurement value calibration method according to claim 2. In an exposure apparatus that illuminates a pattern with an exposure beam and transfers the pattern onto a photoconductor via a projection optical system,
An exposure apparatus comprising the calibrated polarization measuring device according to claim 3 for measuring a polarization state of the exposure beam. In a polarization measuring device calibration device that measures the polarization state of incident light,
A light source that generates luminous flux;
A polarization measuring device calibration apparatus comprising: a polarization optical system that includes at least one polarizer, sets a polarization state of a light beam generated from the light source to a predetermined state, and supplies the polarization state to the polarization measuring device . A beam splitter for branching a part of the light beam from the light source;
6. The polarization measuring device calibration apparatus according to claim 5, further comprising a light amount monitor that detects a light amount of a light beam branched by the beam splitter. The light source is a laser light source that generates linearly polarized laser light,
The polarization measuring apparatus calibration apparatus according to claim 5, further comprising a half-wave plate disposed in a rotatable state between the laser light source and the polarization optical system.   The calibration apparatus for a polarization measuring device according to claim 5, further comprising a rotation mechanism that rotates the polarization optical system. A diffractive optical element that diffracts the light beam in a plurality of directions and an objective optical system that collects the light beam diffracted in the plurality of directions are arranged between the polarization optical system and the polarization measuring device. The calibration apparatus for a polarization measuring device according to claim 5.   The polarization measuring device calibration apparatus according to claim 9, further comprising a liquid supply mechanism that supplies a liquid between the objective optical system and the polarization measuring device. In the method of measuring the phase delay amount of the optical element to be tested,
A linearly polarized light beam is incident on a photoelectric detector via a polarization optical system including at least one polarizer, and the light beam and the polarization optical system are relatively rotated so that the output of the photoelectric detector is minimized or maximized. A first step of
A second step of causing the light beam to enter the polarization optical system via the test optical element and obtaining a reference rotation angle of the test optical element when the output of the photoelectric detector is minimized or maximized;
The test optical element is rotated by a predetermined angle with respect to the reference rotation angle, the light beam is supplied to the photoelectric detector via the test optical element and the polarization optical system, and the output of the photoelectric detector is minimized. Or a third step of obtaining a rotation angle of the polarizing optical system when maximizing.
And a fourth step of obtaining a phase delay amount of the optical element to be measured based on the rotation angle obtained in the third step. The relationship between the rotation angle of the polarizing optical system and the transmittance of the polarized optical system with respect to the incident light of the linearly polarized light is obtained in advance and stored,
The phase delay amount measurement according to claim 11, wherein in the first step and the third step, the output of the photoelectric detector is corrected based on the relationship and the rotation angle of the polarization optical system. Method. 13. A wavelength plate, wherein the phase delay amount is measured by the phase delay amount measuring method according to claim 11.

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