JP2010249627A - Method and device for polarization measurement, and method and device for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure polarization characteristics of two optical systems respectively, by detecting illumination light passing through the two optical systems. <P>SOLUTION: A method for measuring the polarization characteristics of an illumination optical system ILS and a projection optical system PL is provided, which includes: the step of measuring a first polarization characteristic of the illumination light IL passing through the illumination optical system ILS and the projection optical system PL; the step of arranging a prism part 22A between the illumination optical system ILS and the projection optical system PL; the step of measuring a second polarization characteristic of the illumination light IL passing through the illumination optical system ILS, the prism part 22A and the projection optical system PL; and the step of obtaining respective polarization characteristics of the illumination optical system ILS and the projection optical system PL, based on the first and second polarization characteristics. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polarization measurement technique that detects illumination light that has passed through two optical systems and measures the polarization characteristics of the two optical systems, and an exposure technique that uses this polarization measurement technique.

  For example, a batch exposure type projection exposure apparatus such as a stepper used in a lithography process for manufacturing a micro device (electronic device) such as a semiconductor device or a liquid crystal display element, or a scanning exposure type projection exposure apparatus such as a scanning stepper. In such an exposure apparatus, the numerical aperture of the projection optical system is increased to increase the resolution, and the exposure wavelength is shortened. Recently, in order to further improve imaging characteristics such as resolution and depth of focus, polarized illumination using illumination light controlled to a predetermined polarization state has also been proposed. When polarized illumination is used in this way, the polarization characteristic of illumination light emitted from the projection optical system is represented by a Stokes parameter. Therefore, in order to measure the Stokes parameters related to the projection optical system with high accuracy on-body in the exposure apparatus, a measurement apparatus that can be incorporated into a stage that moves on the image plane side of the projection optical system has been proposed (for example, Patent Document 1).

JP 2006-179660 A

  Conventional measuring apparatuses detect illumination light emitted from the illumination optical system of the exposure apparatus and further passed through the projection optical system. Therefore, the Stokes parameters actually measured include the polarization characteristics of the projection optical system. However, there is a problem that the polarization characteristics of the illumination optical system are included. In order to measure the polarization characteristics of only the illumination optical system, the Stokes parameter measurement device may be moved to the object plane side (eg, reticle stage) of the projection optical system, but the exposure device is usually housed in an environmental chamber. Therefore, it is difficult to move the measurement apparatus between the image plane side and the object plane side of the projection optical system.

  In view of such problems, the present invention provides a polarization characteristic measurement technique that can detect illumination light that has passed through two optical systems and measure the polarization characteristics of the two optical systems, and a polarization characteristic measurement technique thereof. An object is to provide an exposure technique to be used.

  A polarization characteristic measuring method according to the present invention is a method for measuring polarization characteristics of a first optical system and a second optical system on which illumination light that has passed through the first optical system is incident. A step of measuring the first polarization characteristic of the illumination light emitted from the second optical system via the first optical system, the first optical system and the second optical system And a step of disposing an optical path deflecting member for deflecting the illumination light, supplying the illumination light in the predetermined polarization state to the first optical system, and the second optical via the first optical system. Measuring a second polarization characteristic of the illumination light emitted from the system; obtaining a polarization characteristic of the first optical system and the second optical system based on the first and second polarization characteristics; , Including.

An exposure method according to the present invention is an exposure method in which a pattern is illuminated with illumination light from an illumination optical system, and an object is exposed with the illumination light through the pattern and the projection optical system. It is used to determine the polarization characteristics of the illumination optical system and the projection optical system.
In addition, the polarization measuring device according to the present invention is a device for measuring the polarization characteristics of the first optical system and the second optical system on which the illumination light that has passed through the first optical system is incident. A light source device that supplies illumination light in a state, a polarization property measuring device that measures the polarization property of the illumination light emitted from the second optical system via the first optical system, the first optical system, and the An optical path deflecting member that deflects the illumination light and is disposed between the second optical system and the second optical system, which is measured by the polarization characteristic measuring device, from the second optical system. Based on the first polarization characteristic of the emitted illumination light and the second polarization characteristic of the illumination light emitted from the second optical system via the first optical system and the optical path polarization member, Obtain polarization characteristics of the first optical system and the second optical system And calculation device, in which comprises a.

  An exposure apparatus according to the present invention illuminates a pattern with illumination light from an illumination optical system, and in the exposure apparatus that exposes an object with the illumination light through the pattern and the projection optical system, the illumination optical system and the projection thereof. In order to obtain the polarization characteristics of the optical system, the polarization measuring device of the present invention is used.

  According to the present invention, there is a case where there is no optical path deflecting member between the first optical system and the second optical system, and there is a relative position between the illumination light passing through the first optical system and the second optical system. By utilizing the change, the polarization characteristics of the first optical system and the second optical system can be obtained separately from the first and second polarization characteristics.

1A is a partially cutaway view showing a schematic configuration of an exposure apparatus as an example of an embodiment, and FIG. 1B is a perspective view showing a test reticle of FIG. It is a figure which shows the structure of the polarization measurement unit 16 in FIG. 1 (A). It is a flowchart which shows an example of the method of measuring each polarization characteristic of an illumination optical system and a projection optical system. (A) is a diagram showing a polarization measurement unit 16 that detects illumination light that has passed through the illumination optical system and the projection optical system without going through the prism unit 22A, and (B) shows the illumination optical system and projection optics through the prism unit 22A. It is a figure which shows the polarization measurement unit 16 which detects the illumination light which passed the system. (A) is a diagram showing a part of the Stokes parameter measured for the first time, (B) is a diagram showing a part of the Stokes parameter measured for the second time, (C) is the first measurement result and the second time It is a figure which shows a part of difference with this measurement result. It is a figure which shows the Fresnel lens part formed in a test reticle.

Hereinafter, an exemplary embodiment of the present invention will be described with reference to FIGS.
FIG. 1A shows a schematic configuration of the exposure apparatus of the present embodiment. In FIG. 1A, an ArF excimer laser light source (wavelength 193 nm) having a narrow oscillation wavelength is used as the light source 1 for exposure. In addition, a KrF excimer laser light source (wavelength 248 nm), F ₂ A laser light source (wavelength 157 nm) or the like can also be used. The illumination light (exposure light) IL emitted from the light source 1 is a linearly polarized laser beam having a polarization degree VP of, for example, 0.95 or more. The degree of polarization VP of the light beam can be expressed as follows using Stokes parameters S ₀ , S ₁ , S ₂ , S ₃ defined by the following equation of the light beam.

VP = (S ₁ ² + S ₂ ² + S ₃ ² ) ^1/2 / S ₀ (A1)
S ₀ : Total intensity of luminous flux (A2)
S ₁ : X-axis and Y-axis are axes perpendicular to each other in a plane perpendicular to the optical axis, and the intensity of the linearly polarized light component (vertically polarized light) in the Y direction is subtracted from the intensity of the linearly polarized light component (transversely polarized light) in the X direction. Difference intensity (A3)
S ₂ : Differential intensity obtained by subtracting the intensity of the linearly polarized light component (135 ° polarized light) in the direction orthogonal to the intensity of the linearly polarized light component (45 ° polarized light) in the direction inclined by 45 ° with respect to the X direction (A4)
S _3: the difference intensity by subtracting the intensity of the circularly polarized light component of the left-handed from the intensity of the circularly polarized light component of the right-handed ... (A5)
Illumination light IL, which is composed of substantially parallel light beams emitted from the light source 1 and has a predetermined rectangular cross section, enters the polarization state variable section 3 via a known beam transmission system 2. The polarization state variable unit 3 has a function of changing the polarization state of the illumination light IL with respect to a reticle R (mask), which will be described later, and eventually the wafer W (substrate). As an example, the polarization state varying unit 3 has a rotatable half-wave plate (not shown), a rotatable quarter-wave plate (not shown), and a thickness that gradually increases in a direction perpendicular to the crystal optical axis. A depolarizing plate (not shown) which is composed of a quartz plate and a quartz plate having a shape that cancels out the change in thickness thereof can be exchanged.

In this case, by using the polarization state varying unit 3, the polarization direction of the emitted illumination light IL can be set to an arbitrary direction. Furthermore, by using a depolarizing plate in the polarization state variable unit 3, the emitted illumination light IL can be set to non-polarized light (random polarized light).
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 composed of a large number of secondary light sources is formed on the exit surface (pupil surface of the illumination optical system) by light beams from a large number of micro lenses having positive refractive power constituting the micro fly's eye lens 5. The illumination intensity distribution is made uniform by superimposing the illumination light IL. A diffractive optical element or the like may be used to define the shape of the surface light source. Furthermore, instead of the micro fly's eye lens 5, an optical integrator (homogenizer) such as 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 reticle blind 7 in which an opening for defining the shape of the illumination area on the reticle R is formed via the first relay optical system 6. The illumination light IL that has passed through the opening of the reticle blind 7 passes through the second relay optical system 8A, the condenser optical system 8B, and the mirror 9 for bending the optical path uniformly on the reticle R on which the transfer pattern is formed. Illuminate with illumination distribution. The illumination optical system ILS includes members from the beam transmission system 2 to the condenser optical system 8B and the mirror 9. The operations of the light source 1, the polarization state varying unit 3, and the beam shape varying unit 4 are controlled by an illumination system control unit in the main control system 11 that is composed of a computer and controls the overall operation of the apparatus.

Under the illumination light IL, the pattern of the reticle R is transferred and exposed onto the wafer W coated with a resist via the projection optical system PL. Hereinafter, the Z-axis is taken perpendicular to the optical axis AX of the projection optical system PL, the X-axis is oriented in a direction parallel to the paper surface of FIG. 1A within a plane perpendicular to the Z-axis, and the paper surface of FIG. A description will be given taking the Y axis in the vertical direction.
Predetermined optical members constituting the projection optical system PL of the present embodiment, for example, the lens elements 14A and 14B, include a lens frame (not shown) and three drive elements (for example, piezo elements) 13A and 13B that can expand and contract in the Z direction. Via the lens barrel. The imaging characteristic control unit in the main control system 11 drives the drive elements 13A and 13B via the drive system 12, so that the positions of the lens elements 14A and 14B in the Z direction and around the X axis and the Y axis are determined. The tilt angle can be controlled. As a result, the imaging characteristics of the projection optical system PL are controlled so as to correct, for example, a fluctuation amount predicted according to the integrated irradiation amount of the illumination light IL. Note that when controlling the imaging characteristics of the projection optical system PL, the polarization characteristics measured using the polarization measurement unit 16 described later may be taken into consideration. Further, the position and the number of the lens elements 14A and 14B that can be driven can be arbitrarily set according to the imaging characteristics to be controlled.

  Next, the reticle R is held on the reticle stage RST, and the reticle stage RST is in a plane perpendicular to the optical axis AX on the reticle base (not shown) based on the measurement value of the laser interferometer (not shown). Move or position R. On the other hand, wafer W is held on wafer stage WST, and wafer stage WST performs continuous movement and step movement in a plane perpendicular to optical axis AX on wafer base WB based on the measurement value of a laser interferometer (not shown). Do. 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 Z stage mechanism for controlling the inclination angle.

  At the time of exposure, the alignment of the reticle R and the wafer W is performed by an alignment system (not shown) under the control of the exposure control unit in the main control system 11, and then the polarization state of the illumination light IL by the polarization state variable unit 3 Is set to a predetermined state. Thereafter, light emission of the light source 1 is started, and the operation of transferring the pattern of the reticle R to one shot area on the wafer W via the projection optical system PL by the batch exposure method or the scanning exposure method, and the light emission of the light source 1 The operation of stopping and stepping the wafer W is repeated. As a result, the pattern of the reticle R is transferred to all shot areas on the wafer W. Further, when the exposure apparatus of the present embodiment is of an immersion type as disclosed in, for example, US Patent Application Publication No. 2007/242247 or European Patent Application Publication No. 1420298, projection optics A liquid such as pure water is supplied between the system PL and the wafer W from a liquid supply mechanism (not shown).

Now, for such exposure, the imaging characteristics of the projection optical system PL must be adjusted to a predetermined state. For this purpose, first, it is necessary to measure the imaging characteristics with high accuracy. Therefore, a measurement stage MST is movably mounted on wafer base WB in parallel with wafer stage WST. Polarization measurement unit 16 for measuring the Stokes parameter of incident light and projection optical system PL are mounted on measurement stage MST. And a wavefront aberration measuring device (not shown) for measuring the wavefront aberration. The polarization measurement unit 16 may be set to be detachable from the measurement stage MST. Further, the measurement stage MST may be omitted, and the polarization measurement unit 16 may be installed on the wafer stage WST. As will be described later, the measurement unit 17 controls the polarization measurement unit 16 and processes the detection signal to obtain the Stokes parameters S _{0 to} S ₃ defined by the above formulas (A2) to (A5). The individual Stokes parameters of the system ILS and the projection optical system PL are obtained and supplied to the main control system 11.

  Further, the exposure apparatus can be replaced with an exposure reticle R and loaded on the reticle stage RST at any time, and a test reticle R1 used when measuring the polarization characteristics of the illumination optical system ILS and the projection optical system PL. Is provided. The pattern region of the test reticle R1 is a complete transmission surface (through surface), and on the upper surface on the half surface side of the pattern region, as shown in FIG. A prism portion 22A for slightly bending (deflecting) the optical path of the illumination light IL is formed.

  FIG. 2 shows a configuration of the polarization measurement unit 16 in FIG. In FIG. 2, the illumination light IL passes through the pinhole 90 a of the pinhole member 90 when measuring the polarization state of the illumination light IL that has passed through the projection optical system PL of FIG. Illumination light IL that has passed through the pinhole 90a is converted into a substantially parallel light beam via a collimator lens 91, reflected by a mirror 92, and then a relay lens system 93, a quarter-wave plate 94 (phase shifter), PBS The light is incident on a detection surface 96 a of a two-dimensional image sensor 96 made of, for example, a CCD via a (polarization beam splitter) 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 unit 16 includes the members from the pinhole member 90 to the image sensor 96 and the drive unit 97.

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 17. The measuring unit 17 obtains Stokes parameters S _{0 to} S ₃ indicating the polarization state of the illumination light IL by using, for example, the rotational phase shift method based on the information regarding the rotation angle and the light amount distribution information. 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 ¼ wavelength plate 94 is Γ (approximately 90 °) and is incident on one pixel of the image sensor 96. It is assumed that the measured value of the transmittance (parallel transmittance) of the PBS 95 regarding the P-polarized illumination light is tx, and the measured value of the transmittance (vertical transmittance) of the PBS 95 regarding 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.

   FIGS. 4A and 4B show the illumination light IL from the illumination optical system ILS with the test reticle R1 and the projection optics in a state where the test reticle R1 is loaded on the reticle stage RST of FIG. 1A, respectively. The case where light is received by the polarization measurement unit 16 on the measurement stage MST via the system PL will be described. The schematic configuration of the illumination optical system ILS and the polarization measurement unit 16 is shown. 4A and 4B, the optical system from the pinhole member 90 to the image sensor 96 in FIG. 2 is collectively represented by a collimator lens 91T. Also, the pupil plane PIL (illumination pupil plane: optical Fourier transform plane for the pattern surface of the reticle R or the test reticle R1) of the illumination optical system ILS and the pupil plane PPL (plane conjugate with the exit pupil) of the projection optical system PL Is optically conjugate, and the pupil plane PPL of the projection optical system PL and the detection surface of the image sensor 96 are optically conjugate. In other words, an image 25P of the region 25 defined by, for example, an aperture stop (not shown) on the pupil plane PIL of the illumination optical system ILS is defined by the aperture stop (not shown) on the pupil plane PPL of the projection optical system PL. The image 25P and the image of the region 26 are formed on the detection surface of the image sensor 96.

Accordingly, the values of the Stokes parameters S _{0 to} S ₃ measured for a large number of pixels arranged in the X direction and the Y direction on the detection surface of the image sensor 96 on the pupil plane PPL of the projection optical system PL, respectively. The Stokes parameter of the illumination light IL that has passed through the corresponding position in the region 26 and the corresponding position in the region 25 on the pupil plane PIL of the illumination optical system ILS. Therefore, in the following, the Stokes parameter measured through the polarization measuring unit 16 is treated as a function of the coordinates (X, Y) in the region 26 on the pupil plane PPL of the projection optical system PL.

A detailed method for measuring the Stokes parameters by the polarization measurement unit 16 and an accurate measurement method for the retardation amount (Γ) of the quarter-wave plate 94 in the polarization measurement unit 16 and the transmittances tx and ty of the PBS 95, etc. Is disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-179660.
Next, in the exposure apparatus of this embodiment, the flowchart of FIG. 3 shows an example of a method for measuring the polarization characteristics (Stokes parameters) of the illumination optical system ILS and the projection optical system PL using the measurement result by the polarization measurement unit 16. Will be described with reference to FIG. The operation at this time is controlled by the main control system 11.

First, in step 101 of FIG. 3, the test reticle R1 is loaded on the reticle stage RST of FIG. Furthermore, the polarization state of the illumination light IL emitted from the polarization state variable unit 3 of the illumination optical system ILS is set to linear polarization in a predetermined direction, for example. In the next step 102, as shown in FIG. 4A, the measurement stage MST is driven to move the polarization measurement unit 16 to the first measurement position. At the first measurement position, the illumination light IL emitted from the illumination optical system ILS and transmitted through the flat plate portion of the test reticle R1 enters the pinhole 90a of the polarization measurement unit 16 via the projection optical system PL. In this state, in step 103, the illumination optical system ILS irradiates the test reticle R1 with the illumination light IL for a predetermined time, and the polarization measuring unit 16 captures the illumination light IL that has passed through the flat portion of the test reticle R1 and the projection optical system PL. The Stokes parameters S _{0 to} S at each coordinate (X, Y) on the pupil plane PPL of the projection optical system PL are detected by the element 96 and based on the equations (B1) to (B4) in the measurement unit 17 as described above. ₃ (hereinafter referred to as the first set of Stokes parameters ST1 (X, Y)).

  For example, when the exposure apparatus is a scanning exposure type, the pinhole 90a of the polarization measuring unit 16 is disposed on the optical axis AX of the projection optical system PL, and the prism portion 22A of the test reticle R1 is separated from the optical axis AX. The measurement may be performed at step 103 by moving to a different position. In this case, the first and second measurement positions are set to the same position, and during the subsequent measurement, the reticle stage RST is driven to move the prism portion 22A of the test reticle R1 onto the optical axis AX. .

  In the next step 104, as shown in FIG. 4B, the measurement stage MST is driven to move the polarization measurement unit 16 to the second measurement position. At the second measurement position, the illumination light IL emitted from the illumination optical system ILS and transmitted through the prism portion 22A of the test reticle R1 and slightly deflected in the + X direction is polarized by the polarization measurement unit 16 via the projection optical system PL. Is incident on the pinhole 90a. In this case, since the illumination light IL is deflected by the prism portion 22A, the position of the image 25P of the region 25 on the pupil plane PIL of the illumination optical system ILS on the pupil plane PPL of the projection optical system PL is as shown in FIG. ) In the X direction is shifted laterally by δX, which is a distance determined by the average deflection angle by the prism portion 22A and the focal length of the projection optical system PL.

In this state, in step 105, as in step 103, the illumination light IL irradiated from the illumination optical system ILS for a predetermined time is input to the imaging element of the polarization measuring unit 16 via the prism portion 22A of the test reticle R1 and the projection optical system PL. The Stokes parameters S _{0 to} S ₃ (hereinafter referred to as a second set of Stokes parameters ST2 (X, Y)) at each coordinate (X, Y) on the pupil plane PPL of the projection optical system PL in the measurement unit 17 are detected. ) In the next step 106, the measurement unit 17 determines the illumination optical system from the difference between the first set of Stokes parameters ST1 (X, Y) and the second set of Stokes parameters ST2 (X, Y) as described below. Find the ILS Stokes parameters.

  In this case, as an example, a plurality of measurement points set at the interval δX in the region 26 on the pupil plane PPL of the projection optical system PL in FIGS. 4A and 4B are respectively shown in FIGS. Assume that the measurement point Q (j) (j = 1, 2,...) In FIG. In addition, among the first set of Stokes parameters ST1 (X, Y) measured in step 103, a value measured for the measurement point Q (j) in FIG. 5A is ST1 (j). Of the polarization characteristics of the illumination light passing through the measurement point Q (j), the polarization characteristics (here, the Stokes parameter) attributed to the illumination optical system ILS are si (j), and the polarization characteristics attributed to the projection optical system PL are the polarization characteristics. Assuming sp (j), the Stokes parameter ST1 (j) measured for each measurement point Q (j) is the sum of the two polarization characteristics as follows (see FIG. 5A).

ST1 (j) = sp (j) + si (j) (1)
Furthermore, a value measured for the measurement point Q (j) in FIG. 5B among the second set of Stokes parameters ST2 (X, Y) measured in step 105 is ST2 (j). In this case, the illumination light IL from the illumination optical system ILS incident on the measurement point Q (j) in FIG. 5B is incident on the adjacent measurement point Q (j−1) in FIG. It is equivalent to light. Therefore, the Stokes parameter ST2 (j) measured for each measurement point Q (j) in FIG. 5B is the sum of sp (j) and si (j-1) as follows.

ST2 (j) = sp (j) + si (j-1) (2)
Therefore, the difference between the equations (1) and (2) is obtained as follows (see FIG. 5C).
ST1 (j) -ST2 (j) = si (j) -si (j-1) (j = 2, 3,...) (3)
ST1 (1) -ST2 (1) = si (1) (4)
Therefore, the Stokes parameter si (1) of the illumination light passing through the position on the pupil plane of the illumination optical system ILS conjugate with the measurement point Q (1) in the state of FIG. it can. Further, si (1) is substituted into equation (3), si (2) is calculated, and si (j-1) is sequentially substituted into equation (4), whereby the illumination optical system ILS is placed on the pupil plane. The Stokes parameter si (j) for a series of measurement points set at intervals corresponding to the interval δX can be obtained. Further, the Stokes parameter of a point between two adjacent measurement points may be obtained by interpolation of Stokes parameters si (j−1) and si (j) before and after the measurement point. Further, by performing the above-described processing on a plurality of rows of measurement points arranged in the Y direction on the pupil plane PPL of the projection optical system PL, a large number of measurement points distributed over the entire pupil plane of the illumination optical system ILS. The Stokes parameter si (X, Y) can be determined for.

In the next step 107, the measurement unit 17 subtracts the Stokes parameter si (X, Y) of the illumination optical system ILS obtained in step 106 from the first set of Stokes parameters ST1 (X, Y) obtained in step 103. Thus, the Stokes parameter sp (X, Y) of the projection optical system PL for each measurement point Q (j) is obtained as follows.
sp (X, Y) = ST1 (X, Y) -si (X, Y) (5)
The Stokes parameters si (X, Y) of the illumination optical system ILS and the Stokes parameters sp (X, Y) of the projection optical system PL thus obtained are supplied to the main control system 11.

Effects and the like of this embodiment are as follows.
(1) The polarization characteristic measuring device provided in the exposure apparatus of the present embodiment is a device that measures the Stokes parameters (polarization characteristics) of the illumination optical system ILS and the projection optical system PL. A light source 1 that supplies illumination light IL in a predetermined polarization state, a polarization measurement unit 16 that measures a Stokes parameter of illumination light IL emitted from projection optical system PL via illumination optical system ILS, and illumination optical system ILS. Illuminating light that passes through the illumination optical system ILS and the projection optical system PL and is measured by the polarization measuring unit 16 and the prism unit 22A that deflects the illumination light IL. A first set of Stokes parameters of IL and a second set of Stokes of illumination light IL that has passed through illumination optical system ILS, prism unit 22A, and projection optical system PL Based on the parameters, but with a measuring unit 17 for determining the Stokes parameters of the illumination optical system ILS and the projection optical system PL, a.

  Further, the polarization characteristic measuring method of the present embodiment includes a step 103 for obtaining a first set of Stokes parameters of the illumination light IL emitted from the projection optical system PL via the illumination optical system ILS, and substantially the illumination optical system. Step 104 of arranging the prism portion 22A of the test reticle R1 between the ILS and the projection optical system PL, and a second set of illumination light IL emitted from the projection optical system PL via the illumination optical system ILS and the prism portion 22A The step 105 for obtaining the Stokes parameters of the illumination optical system ILS and the projection optical system PL from the first set and the second set of Stokes parameters are included.

  According to the present embodiment, when there is no prism portion 22A between the illumination optical system ILS and the projection optical system PL, when there is the prism portion 22A, the region 25 on the pupil plane of the illumination optical system ILS. And the region 26 on the pupil plane of the projection optical system PL are relatively laterally displaced. Therefore, for example, the Stokes parameters of the illumination optical system ILS and the projection optical system PL can be obtained separately by calculating the difference between the first set and the second set of Stokes parameters.

Accordingly, it is possible to adjust the polarization characteristics of the illumination optical system ILS and the polarization characteristics of the projection optical system PL to desired states, respectively.
(2) In Step 106, the difference between the first and second sets of Stokes parameters is the difference between the Stokes parameters for adjacent measurement points on the pupil plane of the illumination optical system ILS. Therefore, the Stokes parameters for each measurement point of the illumination optical system ILS can be easily obtained by integrating the differences.

  (3) In this embodiment, in step 105, the illumination light IL from the illumination optical system ILS is guided to the projection optical system PL via the prism portion 22A. Therefore, the illumination light IL from the illumination optical system ILS can be deflected in the vicinity of the object plane of the projection optical system PL with a simple configuration. Thereby, the image of the pupil plane of the illumination optical system ILS and the pupil plane of the projection optical system PL can be easily laterally shifted.

  (4) The exposure apparatus of the present embodiment illuminates the reticle R with the illumination light IL from the illumination optical system ILS, and exposes the wafer W with the illumination light IL via the reticle R and the projection optical system PL. In order to measure the polarization characteristics of the illumination optical system ILS and the projection optical system PL, a measurement apparatus including the polarization measurement unit 16, the test reticle R1, and the measurement unit 17 of the present embodiment is provided.

In the exposure method of the present embodiment, the polarization characteristics of the illumination optical system ILS and the projection optical system PL are obtained using the polarization characteristic measurement method of the present embodiment.
Therefore, since the polarization characteristics of the projection optical system PL can be adjusted with high accuracy, the image of the pattern of the reticle R can be exposed on the wafer W with high accuracy when performing polarized illumination.
The above-described embodiment can be modified as follows.

(1) The two optical systems for measuring the polarization characteristics (illumination optical system ILS and projection optical system PL in the above embodiment) do not need to be arranged continuously, for example, between the two optical systems to be measured. The present invention can also be applied to a case where a third optical system (for example, an optical system with a known polarization characteristic) that is not a measurement target is arranged.
(2) The prism portion 22A is formed on a part of the test reticle R1, but when the exposure apparatus is a scanning exposure type, the prism (or other optical path deflecting member) is used as the reticle R on the reticle stage RST. On the other hand, it may be fixed at a position adjacent in the scanning direction. In this case, when the prism is disposed between the illumination optical system ILS and the projection optical system PL, the reticle stage RST may be moved.

(3) Instead of the prism portion 22A, a Fresnel lens portion 22B formed on the test reticle R1 may be used as an optical path deflecting member as shown in FIG. A diffraction grating or the like may be used instead of the Fresnel lens portion 22B.
(4) In the above-described embodiment, the illumination optical system ILS and the projection optical system PL are refractive systems or catadioptric systems. When light is used, the illumination optical system and the projection optical system are reflection systems, and the reticle is also a reflection type. As described above, when the present invention is applied when the optical system is a reflection system, it is also possible to use a mirror disposed in the vicinity of the object plane as the optical path deflecting member.

  (5) In the above-described embodiment, the polarization characteristics are represented by Stokes parameters. However, the present invention may be applied to the case where the polarization characteristic is represented by Jones notation such as Jones Matrix. The Jones notation is described in, for example, the reference `` M. Totzeck, P. Graeupner, T. Heil, A. Goehnermeier, O. Dittmann, DSKraehmer, V. Kamenov and DGFlagello: Proc. SPIE 5754, 23 (2005) ''. As described, a Jones matrix composed of a 2 × 2 complex matrix (polarization matrix) for representing the polarization characteristics of the optical system, and 2 for representing the polarization state converted by the optical system. A Jones vector consisting of a complex column vector of rows is described.

In addition, the present invention may be applied to the case where the polarization characteristic is represented by a Mueller matrix. The Mueller matrix is described in, for example, the reference “D. Goldstein, Polarized light, Marcel Dekker Inc., 2003)”.
In addition, 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 be widely applied to various devices such as an image sensor (CCD or the like), a micro machine, a thin film magnetic head, and a DNA chip, and an exposure apparatus for manufacturing a mask itself.

Note that the present invention is not only for measuring the polarization characteristics of the projection optical system and illumination optical system of the exposure apparatus, but for example, for measuring the polarization characteristics of the illumination system and objective optical system of an image processing type sensor, and processing. The present invention can also be applied to a case where two optical systems such as an apparatus and an inspection apparatus are to be measured.
As described above, the present invention is not limited to the above-described embodiment, and various configurations can be taken without departing from the gist of the present invention.

  ILS ... illumination optical system, PL ... projection optical system, R ... reticle, R1 ... test reticle, W ... wafer, 3 ... polarization state variable unit, 11 ... main control system, 16 ... polarization measurement unit, 17 ... measurement unit, 22A ... Prism part

Claims (9)

In the method for measuring the polarization characteristics of the first optical system and the second optical system on which the illumination light having passed through the first optical system is incident,
Supplying illumination light in a predetermined polarization state to the first optical system, and measuring a first polarization characteristic of the illumination light emitted from the second optical system via the first optical system;
Disposing an optical path deflecting member for deflecting the illumination light between the first optical system and the second optical system;
Supplying illumination light in the predetermined polarization state to the first optical system, and measuring a second polarization characteristic of the illumination light emitted from the second optical system via the first optical system;
Obtaining polarization characteristics of the first optical system and the second optical system based on the first and second polarization characteristics;
A polarization measurement method comprising: The step of obtaining the polarization characteristics includes:
The polarization measurement method according to claim 1, further comprising a step of obtaining a polarization characteristic of the first optical system from a difference between the first and second polarization characteristics.   The polarization measurement method according to claim 1, wherein the first and second polarization characteristics are each expressed by a Stokes parameter. In an exposure method of illuminating a pattern with illumination light from an illumination optical system and exposing an object with the illumination light through the pattern and a projection optical system,
An exposure method comprising: determining the polarization characteristics of the illumination optical system and the projection optical system using the polarization measurement method according to claim 1. In the apparatus for measuring the polarization characteristics of the first optical system and the second optical system on which the illumination light having passed through the first optical system is incident,
A light source device that supplies illumination light in a predetermined polarization state to the first optical system;
A polarization characteristic measuring device that measures a polarization characteristic of the illumination light emitted from the second optical system via the first optical system;
An optical path deflecting member that is disposed so as to be able to be inserted and removed between the first optical system and the second optical system, and deflects the illumination light;
The first polarization characteristic of the illumination light emitted from the second optical system via the first optical system, measured by the polarization characteristic measurement device, and the first optical system and the optical path polarization member. And an arithmetic unit for obtaining the polarization characteristics of the first optical system and the second optical system based on the second polarization characteristics of the illumination light emitted from the second optical system;
A polarization measuring device comprising:   The polarization measuring apparatus according to claim 5, wherein the optical path deflecting member is a prism or a Fresnel lens.   The polarization characteristic measuring apparatus includes: a light collecting system that forms a measurement surface substantially conjugate with the pupil plane of the second optical system; and an image sensor that measures a light amount distribution on the measurement surface. The polarization measuring device according to claim 5 or 6. The arithmetic unit is:
The polarization measuring apparatus according to claim 5, wherein a polarization characteristic of the first optical system is obtained from a difference between the first and second polarization characteristics. In an exposure apparatus that illuminates a pattern with illumination light from an illumination optical system and exposes an object with the illumination light through the pattern and the projection optical system,
An exposure apparatus using the polarization measuring device according to any one of claims 5 to 8, in order to obtain polarization characteristics of the illumination optical system and the projection optical system.

Images