JP2005322728A - Aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aligner capable of exposure with high alignment precision. <P>SOLUTION: This aligner comprises an exposure illumination optical system for illuminating a negative plate with predetermined exposure light; a projection optical system for projecting the pattern on the negative plate onto a substrate; and a position detection means for performing position detection with light having a wavelength substantially same as that of the exposure light via the projection optical system. The detection range of the position detection means is made to be the range wherein the precision is assured by the aberration of the projection optical system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus used in a lithography process and a position detection means using exposure light as a light source among processes for manufacturing semiconductor devices such as IC and LSI, imaging devices such as CCD, and display devices such as liquid crystal panels. Therefore, it is suitable for manufacturing a highly integrated device by accurately detecting position information.

  In a lithography process for manufacturing a semiconductor device, an exposure apparatus that projects and projects an original (reticle or photomask) pattern onto a substrate (wafer) through a projection optical system is used.

  The exposure apparatus uses a TTR microscope as a position detection means that performs alignment of the original and the substrate, baseline measurement, calibration measurement of the focal position detection means, detection of the original position of the original stage, and detection of differences in the running of the original stage and the substrate stage. Alternatively, a TTL microscope (in the following description, the term “TTL microscope” includes a TTR microscope) is mounted. Conventionally, a microscope that detects and measures the position of a reticle and wafer via a projection lens is usually called a TTL microscope, but TTL is used when the projection optical system is not a lens but a multilayer mirror optical system. It is hard to say. However, in the present specification, for convenience of explanation, the microscope used for the position detection means via the multilayer mirror optical system is also a TTL microscope.

  The light source of the TTL microscope as the position detection means cuts out light substantially the same as the exposure light from the illumination optical system for exposure and guides it through a fiber or lens optical system.

  In the exposure apparatus as described above, the exposure wavelength of the lithography light source has been shortened in order to cope with the improvement of the integration degree and fineness of the semiconductor device. Currently, ultraviolet ray i-line (wavelength 365 nm), KrF excimer laser light (wavelength 248 nm), and ArF excimer laser light (wavelength 193 nm) are in practical use as exposure illumination light. Furthermore, use of light sources such as F2 laser light (wavelength 157 nm), EUV, and soft X-rays with a short wavelength is planned. Along with the above, the illumination light of the position detection means using exposure light as a light source is also being shortened.

  As a semiconductor manufacturing apparatus used for such semiconductor manufacturing, a scanning (step-and-scan) projection exposure apparatus is known. A scanning projection exposure apparatus (in the following description, the notation of a projection exposure apparatus includes a scanning projection exposure apparatus) includes a pattern of an original (reticle or mask) on a substrate (wafer) via a projection optical system. A projection exposure apparatus that simultaneously scans an original and a substrate with respect to a projection optical system. As the resolution of the projection exposure apparatus improves, the allowable depth of the projection optical system decreases, and it is required to set the substrate surface to the in-focus position of the projection optical system with high accuracy.

  FIG. 2 is a schematic bird's-eye view showing an outline of a conventional first exposure apparatus, FIG. 3 is a schematic plan view, and FIG. 4 shows a detection range of the second position detection means 14.

  An original 1 (reticle) is held on an original stage 2 that is driven and controlled in the Y direction in the figure by a laser interferometer 3 and drive control means (not shown).

  In the vicinity of the original 1, one or a plurality of reference originals 4 are fixed within a predetermined range of the original stage 2. The reflective surface of the reference original plate 4 is almost the same height as the reflective surface of the original plate 1. The reflective surface of the reference original 4 is composed of a plurality of original reference marks formed of a metal surface such as Cr or Al.

  The original stage 2 is driven in a state where the position in the Z direction in the figure is kept constant with respect to the projection optical system 5. A movable mirror 6 that reflects the beam from the laser interferometer 3 is fixed to the original stage 2. The position and movement amount of the original stage 2 are sequentially measured by the laser interferometer 3.

  The pattern on the original 1 is image-exposed on the substrate 8 (wafer) held on the substrate stage 9 by the exposure illumination optical system 7 via the projection optical system 5.

  In the vicinity of the substrate 8, one or a plurality of reference substrates 10 are fixed within a predetermined range of the substrate stage 9. The reflective surface of the reference substrate 10 is substantially flush with the upper surface of the substrate 8. The reflective surface of the reference substrate 10 includes a plurality of reference marks formed of a metal surface such as Cr or Al. A photoelectric conversion element (not shown) is configured under the reference substrate 10.

  The substrate stage 9 has a vertical drive, an image surface blur correction drive, an alignment of the substrate 8 or the reference substrate 10, and a substrate 8 or a reference during yawing control in order to match the substrate 8 with the image plane of the projection optical system. Drive control means (not shown) for rotating the substrate 10 is provided. Further, a movable mirror 12 that reflects the beam from the laser interferometer 11 is fixed to the substrate stage 9. The position and movement amount of the substrate stage 9 are sequentially measured by the laser interferometer 11.

  With the above configuration, the substrate stage 9 can move in the optical axis direction (Z direction) of the projection optical system 5 and in a plane (XY plane) orthogonal to the optical axis direction, and further rotate around the optical axis (θ direction) You can also

  The original plate 1 and the substrate 8 are optically conjugate to each other via a projection optical system 5 by a plurality of position detection means, and an exposure illumination optical system 7 forms a slit-like or arc-shaped exposure region that is long in the X direction. It is formed on the original plate 1. The exposure area on the original 1 is formed on the substrate 8 with a slit-shaped exposure area having a size approximately equal to the projection magnification of the projection optical system 5.

  In the scanning exposure apparatus, both the original stage 2 and the substrate stage 9 are driven at a speed ratio corresponding to the optical magnification of the projection optical system with respect to the exposure optical axis, and the exposure area on the original and the exposure area on the substrate are driven. Scanning exposure is performed by scanning.

  As the focal plane position detection means, a first position detection means 13 of an oblique incidence method is configured. The first position detecting means 13 irradiates the substrate 8 surface (or the reference substrate 10 surface) onto which the pattern of the original 1 is transferred by the projection optical system 5 from an oblique direction, and exposes the surface of the substrate 8 (or the reference substrate). The reflected light that is reflected obliquely from (10 surfaces) is detected. The detection unit of the first position detector 13 includes a plurality of position detection light-receiving elements corresponding to each reflected light. The light-receiving surface of each position detection light-receiving element and the reflection point of each light beam on the substrate 8 They are arranged so as to be almost conjugate. Therefore, the positional deviation of the substrate 8 (or the reference substrate 10) in the optical axis direction of the projection optical system 5 is measured as the positional deviation of the position detection light receiving element in the detection unit.

  However, when the projection optical system 5 absorbs the exposure heat or the surrounding environment changes, the focal position of the projection optical system 5 changes, and the measurement origin and the focal plane of the first position detection means 13 of the oblique incidence method are changed. An error occurs. Therefore, the second position detecting means 14 is mounted to calibrate this error.

  As shown in FIG. 2, the second position detection means 14 includes two detection systems, a first detection system 14a and a second detection system 14b. The two detection systems 14a and 14b extract substantially the same light as the exposure light from the exposure illumination optical system 7 and guide it through a fiber or lens optical system. The guided light illuminates the vicinity of the focus mark on the reference original. At least one or more optical systems in the second position detection means 14 are driven in the direction of the detection optical axis, and the detection focal plane of the second position detection means 14 is aligned with the focus mark of the reference original 4. Next, the substrate stage 9 is driven up and down in the optical axis direction (Z direction) in the vicinity of zero preset by the first position detecting means 14 of the oblique incidence method. Note that the reference substrate 10 is positioned almost directly below the projection optical system 5 during driving. The light that has passed through the focus mark of the reference original 4 passes through the projection optical system 5 and irradiates the reference substrate 10. The light reflected by the reference substrate 10 passes through the projection optical system 5 again and enters the light receiving portion of the second position detection means 14 via the reference original plate 4. The reference substrate 10 can be focused on the reference original 4 by measuring the amount of light incident on the light receiving unit.

  Since the second position detection means 14 estimates the actual exposure image plane from the measured values of the left and right two points on the X axis, the two detection systems 14a and 14b are arranged in the X axis including the exposure optical axis as shown in FIG. Each detection range is on a straight line, and the detection ranges of the first detection system 14a and the second detection system 14b are substantially symmetrical with respect to the exposure optical axis. During the exposure, the first detection system 14a and the second detection system 14b are evacuated so as not to block the exposure light, and stand by at a position away from the exposure area.

In the configuration of the exposure apparatus previously proposed by the present inventor, the second position detection means 14 includes three detection systems, a first detection system 14a, a second detection system 14b, and a third detection system 14c. . (Japanese Patent Application 2002-355685, Japanese Patent Application 2003-064107)
FIG. 5 is a schematic bird's-eye view showing an outline of a conventional second exposure apparatus, FIG. 6 is a schematic plan view, and FIG. 7 shows a detection range of the second position detection means.

  Each of the detection systems 14a, 14b, and 14c is individually configured with a drive system for detecting within an arbitrary detection range. The first detection system 14a and the second detection system 14b can arbitrarily move the detection ranges 14a1 and 14b1 in a direction (X direction in the drawing) substantially orthogonal to the scanning direction of the original stage 2; The detection system 14c can move the detection range 14c1 in a direction (Y direction in the figure) substantially parallel to the scanning direction of the original stage. When performing detection using the detection system, it is possible to select one, a plurality or all of arbitrary detection systems. In addition, when calculating the position based on the selected detection result, one or a plurality of detection results can be arbitrarily selected. The detection ranges 14a1 and 14b1 of the first detection system 14a and the second detection system 14b are arranged substantially symmetrically with respect to the exposure optical axis. The third detection system 14c can detect the exposure optical axis. Each of the detection systems 14a, 14b, and 14c is retracted to a position where the exposure light is not shielded when the original pattern is exposed on the substrate. Alternatively, it is stationary at a position where the exposure light is not blocked.

  The detection system includes a plurality of position sensors so as not to interfere with each other's detection system, and is controlled by a drive control unit (not shown).

  The second position detection means 14 cuts out substantially three light beams from the exposure illumination optical system 7 and guides them individually to the detection systems 14a, 14b, and 14c. The method of branching the three light beams is a method of branching into three light beams in the exposure illumination optical system 7 and guiding them to each detection system, or branching into two light beams in the exposure illumination optical system 7, One beam is further branched in the second position detection means 14 and the three light beams are guided to each detection system, or introduced from the exposure illumination optical system 7 with one beam, and the second position detection means 14 There is a method of branching into a light beam and guiding it to each detection system.

  The illumination optical system that guides light from the exposure illumination optical system 7 to the second position detection means 14 may be guided by a flexible optical system such as a fiber, or may be guided by an optical system such as a lens or a mirror. Especially in a scanning exposure apparatus using a short wavelength laser such as KrF excimer laser (λ = 248 nm), ArF laser (λ = 193 nm), F2 laser (λ = 158 nm) as exposure light, the attenuation of exposure light is high. The light is guided in a space that is almost sealed with an inert gas.

  Each detection system 14a, 14b, 14c is configured with an attenuation glass capable of individually selecting an attenuation rate (not shown) so that a difference in light quantity between the detection systems can be corrected or adjusted.

  The second position detection means 14 also serves as position detection means for detecting the mutual position of the reference original 4 and the reference substrate 10. The detection result is an element for calculating the baseline of the off-axis microscope 15 and the off-axis microscope 16. Here, the base line is the distance between the shot center when aligning the substrate and the shot center (optical axis of the projection optical system) when exposing. The off-axis microscope 15 is a non-TTL (Through The Lens) microscope using non-exposure light, and the off-axis microscope 16 is a TTL microscope using non-exposure light.

  The off-axis microscope 15 and the off-axis microscope 16 are microscopes that detect the position of the alignment mark on the substrate 8.

  An example of baseline measurement of the off-axis microscope 15 in the conventional second exposure apparatus will be described below.

  In performing this measurement, at least one detection system of each detection system 14a, 14b, 14c of the second position detection means 14 is driven to the detection range of each detection system. The master reference mark 17 designed on the reference master 2 is moved to the detection range by driving the master stage 2. The substrate reference mark 18 designed on the reference substrate 10 is moved to the detection range by driving the substrate stage 9.

  The relative deviation between the original reference mark 17 and the substrate reference mark 18 is detected by at least one detection system of the second position detection means 14. (First Step) After completion of the first step, the reference substrate mark 19 is moved to the detection range of the off-axis microscope 15. A relative deviation amount between the reference substrate mark 19 and the microscope reference mark 20 fixed to the off-axis microscope 15 is detected. (Second Step) Based on the detection results of the first step and the second step, the baseline of the off-axis microscope 15 is calculated, and the baseline of the off-axis microscope 15 is corrected.

An exposure apparatus that constitutes a catadioptric projection optical system is disclosed in Patent Document 1.
JP 2001-343589 A

  The above-described conventional techniques are beginning to limit the recent high integration and miniaturization techniques. As patterns such as semiconductor integrated circuits are increasingly integrated and miniaturized, as the NA of the projection optical system 5 increases, the depth of focus of the projection optical system 5 becomes shallow, and a high degree of alignment accuracy is required.

  According to the present inventor, by configuring three or more detection systems in the second position detection means 14, it is possible to measure an image plane inclination component in the original scanning direction that could not be measured conventionally. Furthermore, by increasing the number of detection systems, position detection can be performed with higher accuracy than before due to the averaging effect.

  However, higher precision alignment accuracy is required in the future, and it is desired to solve the following problems.

  In the conventional projection exposure apparatus, the second position detection means 14 is used to directly measure the surface position of the substrate via the projection optical system 5, and the connection between the exposure area on the substrate surface and the projection optical system 5 is measured. For the purpose of the focusing mechanism for minimizing the difference from the image plane, the detection range of the second position detection means 14 is usually configured within the exposure area. In addition, since the second position detection means uses exposure light as a light source, the transmission range in the projection optical system is usually set to an aberration guaranteed range for exposure illumination light.

  However, the second position detection means 14 has not only focus detection but also an alignment mechanism. In the alignment mechanism, usually, a plurality of marks are observed, and the position is calculated from the position information of each mark. Therefore, the longer the distance between the detected marks, the higher the accuracy of position detection. However, since the detection range of the second position detection unit as described above is limited, there is a problem that a sufficient distance between marks cannot be obtained.

  In order to improve the resolving power of the exposure apparatus, it is necessary to increase the NA of the projection optical system 5 and to shorten the wavelength of the exposure light. As the short wavelength of exposure light progresses, the required performance of the projection optical system increases, and a large number of lenses are required to drive various aberrations. In addition, as the exposure light has a shorter wavelength, the absorption of light increases and the glass materials that can be constructed are limited. That is, if the number of lenses is not increased, the optical performance cannot be achieved, but if the number of lenses is increased, there is a problem that development is difficult because it causes a decrease in transmittance and an increase in manufacturing cost.

  For this reason, for example, an exposure apparatus having a catadioptric projection optical system as proposed in Japanese Patent Application Laid-Open Nos. 2001-27727 and 2001-343589 has been considered. According to this, a catadioptric exposure apparatus combining a reflective optical system and a refractive optical system can satisfactorily correct various aberrations including chromatic aberration to almost no aberration without causing an increase in the number of lenses. It is said. At that time, in order to correct various aberrations satisfactorily, for example, an exposure apparatus having an arcuate illumination area as proposed in Japanese Patent Laid-Open No. Hei 6-235863 has been considered.

  However, in the exposure apparatus that constitutes the catadioptric projection optical system as described above, an arc-shaped exposure area is conventionally planned from a rectangular exposure area, but the second position detecting means 14 in the arc-shaped exposure area There was a problem where an appropriate detection range was not proposed.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an exposure apparatus that can perform exposure with high alignment accuracy.

  According to the invention of claim 1, an exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and exposure light through the projection optical system, In an exposure apparatus having position detection means for performing position detection with light of substantially the same wavelength, the detection range of the position detection means is substantially the maximum in the projection optical system aberration guarantee range in which the accuracy of the position measurement means is guaranteed. It is a feature.

  The aberration accuracy required for the exposure process in the projection optical system and the aberration accuracy required for measurement do not exactly match. The aberration guarantee range of the projection optical system is not limited to the rectangular or arcuate exposure area, but the aberration is guaranteed by a circle including the entire exposure area.

  According to the present invention, by setting the detection range of the position detection means to the maximum within the aberration accuracy range of the projection optical system required at the time of measurement, the distance between each detected mark can be increased, and the alignment accuracy is improved. It becomes possible to make it.

  According to the invention of claim 2, an exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and exposure light through the projection optical system, In an exposure apparatus having position detection means for performing position detection with light of substantially the same wavelength, the detection range of the position detection means has a substantially maximum range within a projection optical system aberration guarantee range in which exposure accuracy is guaranteed. Yes.

  According to the present invention, a wide detection range can be set by extending the detection range of the position detection means to the projection optical system aberration guarantee range in which the exposure accuracy is guaranteed. Since the detection range is a projection optical system aberration guarantee range in which the exposure accuracy is guaranteed, the projection lens 5 can be transmitted or reflected with an aberration guarantee equivalent to that of the exposure light.

  According to the invention of claim 3, an exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and exposure light through the projection optical system, In an exposure apparatus having position detection means for performing position detection with light having substantially the same wavelength, the detection range of the position detection means has a substantially maximum range in the exposure area of the projection optical system.

  According to the present invention, by setting the detection range of the position detection means to the maximum range of the exposure area, the difference from the imaging plane of the projection optical system in the entire exposure area of the substrate surface can be reduced.

  Further, when the exposure area is changed by the aperture stop of the exposure illumination system, the position detection range is changed according to the exposure area to be changed, so that the imaging plane of the projection optical system is always in the entire exposure area. Difference can be minimized.

  According to the invention of claim 4, an exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and exposure light through the projection optical system, In an exposure apparatus having position detection means for performing position detection with light of substantially the same wavelength, an exposure area is parallel to the arc of a predetermined radius and an arc of a predetermined radius translated from the arc in the original scanning direction. The position detection means includes three or more detection systems, and the first detection range of the detection system is on the original scanning direction axis including the exposure optical axis. The second detection range and the third detection range are on both sides of the first detection range with the original scanning axis including the exposure optical axis as a boundary line, and the first detection range is the arc with respect to the second and third detection ranges. Or a straight line perpendicular to the original scanning direction connecting the second and third detection ranges.

  According to the present invention, in an exposure apparatus having an arc exposure area, three or more detection systems are configured in the position detection means, one detection system is arranged on the convex side of the arc, and two detection systems are arranged on both wings. Thus, the maximum detection range can be set by utilizing the shape of the arc exposure area.

  According to the exposure apparatus of claim 5, an exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and exposure light via the projection optical system In the exposure apparatus having position detecting means for detecting the position with light having substantially the same wavelength as the exposure area, the exposure area is parallel to the arc of a predetermined radius and the arc of a predetermined radius translated from the arc in the original scanning direction. The position detection means includes three or more detection systems, and the first detection range of the detection system is on the original scanning direction including the exposure optical axis. A straight line connecting the second detection range and the third detection range is perpendicular to the original scanning direction, and the second detection range and the third detection range are symmetrical with respect to a straight line in the original scanning direction including the exposure optical axis. ~ The area of the triangle having the apex angle in the third detection range is the largest.

  According to the present invention, in an exposure apparatus having an arc exposure area, three or more detection systems are configured in the position detection unit, and the triangular areas having the corners as the detection ranges of the three detection systems are arranged to be maximized. be able to.

  Since the detection position of the detection system of the second position detection means 14 is not only in the exposure area but also outside the exposure area, it is unnecessary to drive the detection system to the standby position during exposure in the baseline measurement, etc. High-speed position detection can be performed. At the same time, the driving error can be deleted or reduced, so that highly accurate position detection is possible.

  Since the detection position of the detection system of the second position detection means 14 is not only in the exposure area but also outside the exposure area, the master stage 2 can be driven or reduced in the baseline measurement, etc. Can be improved. At the same time, the drive error can be deleted or reduced, so that highly accurate position detection is possible.

  Since the detection position of the detection system of the second position detection means 14 is not only in the exposure area but also outside the exposure area, the substrate stage 9 can be driven or the drive amount can be shortened in the baseline measurement, etc. Can be improved. At the same time, the drive error can be deleted or reduced, so that highly accurate position detection is possible.

  Since the detection range of the third detection system 14c of the second position detection means 14 is between the exposure optical axis and the detection range of the off-axis microscope 15, the original stage 2 and / or the substrate stage 9 in the baseline measurement Since driving elements for driving the apparatus can be shortened or eliminated, position detection with high speed and high accuracy can be performed, throughput of the entire apparatus can be improved, and high accuracy overlay exposure can be performed.

  Baseline measurement of the off-axis microscope 15 or off-axis microscope 16 is possible without moving the detection range of the original stage 2 and / or the substrate stage 9 and the third detection system from the exposure end position. Accordingly, high-speed and high-precision position detection can be performed, the throughput of the entire apparatus can be improved, and high-precision overlay exposure can be performed.

  Since it is possible to perform baseline measurement and the like during exposure using the third detection system 14c of the second position detection means 14, the alignment measurement time in the throughput of the entire apparatus is shortened.

  Since the third detection system 14c of the second position detection means 14 can be used to detect the amount of reticle deformation due to factors such as exposure heat, high-precision overlay exposure is possible.

  The detection range of the second position detection means 14 is not limited to the exposure light illumination area, but can be set widely from the exposure light aberration guarantee area to the measurement light aberration guarantee area. Therefore, position detection measurement using the second position detection means 14 In FIG. 5, the use position detection mark interval is long, and highly accurate position detection is possible.

  Since the detection range of the second position detection means 14 can be set to the maximum range according to the exposure light illumination area, it is possible to reduce the difference from the imaging plane of the projection optical system in the entire exposure area of the surface of the substrate 8. .

  In the second position detecting means 14 configured in the exposure apparatus having an arcuate exposure area, the detection range can be increased by using the arcuate exposure area shape, so that the position detection accuracy can be improved. .

  In the second position detection means 14 configured in the exposure apparatus in which the exposure area is arcuate, a driving range corresponding to the shape of the arcuate exposure area is configured, so a wide driving range of each detection system can be secured, The detection range can be increased. Alternatively, it is possible to set the position detection accuracy at a factory by setting a portion having a small projection optical system aberration as a detection range.

  In the exposure apparatus of the present invention, since the detection range is widened, the mark configurable portion for the second position detecting means 14 on the reference substrate, reticle or wafer is widened, and there are many various measurement marks including spare marks. The design can be further reduced, and restrictions such as reticle design can be relaxed.

  FIG. 6 shows a detection range of the second position detection means 14 configured in the first exposure apparatus of the present invention (in the following description, the expression of the detection range indicates the detection range of the second position detection means 14). 8 and shown in FIG. As shown in FIG. 4, the conventional exposure apparatus normally sets the detection range in the exposure light illumination region (exposure slit) 17 set in the exposure light aberration guarantee region 18, but the detection range of the present invention is the first. 2 includes a measurement optical aberration guarantee range 19 that can guarantee the measurement accuracy of the position detection means 14 (in the following description, the expression of measurement accuracy indicates the measurement accuracy of the second position detection means 14).

  By setting the detection range to the measurement optical aberration guarantee range 19, the present inventor made baseline measurement and reticle stage position measurement using the second position detection means 14 shown in Japanese Patent Application Nos. 2002-355685 and 2003-064107. Since the mark interval length to be measured at the time of measuring the wafer stage position can be made longer, a higher degree of alignment accuracy can be achieved. In particular, the fact that the outside of the exposure slit can be detected in the 14c detection system having a drive shaft in the minor axis direction of the exposure region as shown in FIG. 9 can greatly enjoy the effects of the present invention.

  Even if the detection range cannot be set in the measurement optical aberration guarantee range 19 due to the problem of the apparatus configuration, setting it in the exposure optical aberration guarantee area 18 as shown in FIGS. It is possible to enjoy the effects of the invention. Further, since the detection range is within the exposure light aberration guarantee region 18, there is an advantage that the alignment measurement can be performed within the same aberration guarantee range as the exposure light.

  Even when the exposure light illumination area is limited by a masking blade (not shown) configured in the exposure light illumination optical system, the detection path of the second position detection means 14 is not affected, so the exposure light It is possible to measure the aberration guaranteed area 18 or the measurement optical aberration guaranteed range 19.

  One of the detection methods of the second position detection means 14 in the first exposure apparatus of the present invention is a detection method for detecting the amount of deviation between the exposure optical axis and the reference substrate in the baseline measurement of the off-axis microscope 15. . Examples of this measurement are shown below.

  FIG. 12 shows a first example of baseline measurement.

  According to the first exposure apparatus of the present invention, the detection range of each detection system of the second position detection means 14 includes outside the exposure illumination area. When performing baseline measurement, the detection position of each detection system is arranged so that the standby position at the time of exposure and the detection range substantially match, so that detection can be performed at the standby position at the time of exposure. It is not necessary to drive each detection system to the detection position when performing line measurement. Therefore, since the driving component of the detection system can be deleted in the baseline measurement, the baseline measurement can be performed at high speed and with high accuracy.

  In addition, for example, due to layout constraints, the detection system drive components are reduced even when the detection standby position and the detection range of each detection system are not substantially coincident and close to each other. Can be expected to be effective.

  Further, according to the present embodiment, the original reference mark 17 and the substrate reference mark 18 are detected by at least one detection system of the second detection means 14 without moving the original stage 2 and / or the substrate stage 9. The relative deviation amount is detected, and further, the relative deviation amount between the substrate reference mark 19 and the microscope reference mark 20 of the off-axis microscope is detected by the off-axis microscope 15.

  Baseline measurement can be performed without driving the original stage 2 and / or the substrate stage 9, and the baseline measurement with the drive time or drive accuracy eliminated or reduced can be performed at high speed and with high accuracy. Baseline correction of the off-axis microscope 15 is performed based on the measurement result.

  Further, even if the detection cannot be performed without moving the substrate stage 9 due to, for example, arrangement restrictions around the projection optical system 5, the detection range of the third detection system 14c is set to the exposure optical axis and the off-axis. By using the space between the microscopes 15, the substrate stage position when using the third detection system 14 c and the substrate stage position when using the off-axis microscope 15 when performing the baseline measurement are brought close to the substrate. The driving amount of the stage 9 can be reduced, and an effect can be expected in measurement time and measurement accuracy. In the case of the original stage 2, the same effect can be obtained because the original stage position when using the third detection system 14c and the original stage position when using the off-axis microscope 15 are brought closer to each other when performing baseline measurement. I can expect.

  FIG. 13 shows a second embodiment of baseline measurement.

  As shown in FIG. 13, in the third detection system detection range 14c1, the standby position at the time of exposure and the detection range 14c1 substantially coincide with each other as in the first embodiment of the baseline measurement. Baseline measurement of an off-axis microscope can be performed without driving the original stage 2, the substrate stage 9, and the third detection system 14c at the exposure end position.

  Details of the configuration in this embodiment will be described below.

  As shown in FIG. 13, the third detection system 14c has a detection range not only inside the exposure slit 17 but also outside the exposure slit 17, and the third detection system 14c can detect even at a standby position during exposure. .

  The master reference mark 20 of the reference master 4 is moved to the detection range 14c1 of the third detection system 14c as shown in FIG. 13 by the scanning drive of the master stage 2 by scanning exposure, and is arranged in a detectable range at the end of scanning exposure. .

  The substrate reference mark 21 for the second position detection means of the reference substrate 10 is arranged in a range that can be detected by the third detection system 14c at the end of the scanning exposure as shown in FIG. 12 by scanning driving of the substrate stage 9 by scanning exposure. .

  Furthermore, the substrate reference mark 21 and the substrate reference mark 22 are arranged on the reference substrate 10 so that the off-axis microscope substrate reference mark 22 can be detected by the off-axis microscope 15 at the end of scanning exposure.

  With the above configuration, the relative displacement between the original reference mark 20 and the substrate reference mark 21 is detected by the third detection system 14c without driving the original stage 2, the substrate stage 9, and the third detection system 14c at the scanning exposure end position. Then, the relative shift amount between the reference substrate mark 22 and the microscope reference mark 23 fixed to the off-axis microscope 15 is detected. Based on the detection result, the baseline of the off-axis microscope 15 is calculated.

  By performing this example, baseline measurement can be performed at the exposure end position without driving the original stage 2, the substrate stage 9, and the third detection system 14c, so that the throughput of the entire apparatus can be improved. is there.

  Further, since the driving component is not included in measurement accuracy, highly accurate detection and calculation can be performed.

  FIG. 14 shows a third embodiment of baseline measurement.

  As shown in FIG. 14, in the third detection system detection position 14c1, the standby position at the time of exposure and the detection range 14c1 substantially coincide with each other as in the second embodiment of the baseline measurement. The relative position between the reference original 4 and the reference substrate 10 can be detected by the third detection system 14c at a predetermined position during the exposure, and the reference substrate 10 can be detected by the off-axis microscope 15.

  Details of the configuration in this embodiment will be described below.

  As shown in FIG. 14, the third detection system 14c has a detection range not only inside the exposure slit 17 but also outside the exposure slit 17, and the third detection system 14c can detect at a standby position at the time of exposure.

  The master reference mark 20 of the reference master 4 is moved to the detection position 14c1 of the third detection system 14c as shown in FIG. 14 by the scanning drive of the master stage 2 by scanning exposure, so that it can be detected within a predetermined range during the scanning exposure. Has been placed.

  The substrate reference mark 21 for the second position detecting means 14 of the reference substrate 10 can be detected by the third detection system 14c within a predetermined range during scanning exposure as shown in FIG. 14 by scanning driving of the substrate stage 9 by scanning exposure. Arranged in the range.

  Further, the off-axis microscope substrate reference mark 22 can be detected by the off-axis microscope 15 at the substrate stage position.

  With the above configuration, the relative deviation between the original reference mark 20 and the substrate reference mark 21 is detected by the third detection system 14c within a predetermined range during scanning exposure, and is fixed to the reference substrate mark 22 and the off-axis microscope 15. The relative deviation amount of the microscope reference mark 23 is detected. Based on the detection result, the baseline of the off-axis microscope 15 is calculated. According to the embodiment, it is possible to send the calculation result of the baseline during exposure to an arithmetic processing unit (not shown) and perform correction processing or correction driving to correct baseline fluctuation during exposure.

  Conventionally, baseline measurement is performed after the exposure is completed, but according to the present embodiment, the baseline measurement can be performed or started before the exposure is completed, so that the throughput of the entire apparatus is improved. It is possible.

  In addition, since the measurement accuracy of the second position detection means 14 is also improved in the off-axis microscope 16, the baseline measurement of the off-axis microscope 16 with high accuracy can be performed.

  One of the detection methods of the second position detection means 14 in the scanning exposure apparatus of the present invention is a method of detecting thermal deformation of the reticle during exposure. Examples of this measurement are shown below.

  In the exposure apparatus of the present embodiment, the third detection system 14c can observe the reference substrate 10 even at the standby position during exposure. On the original plate 1, one or more marks used for this measurement are designed. Similarly, one or more marks used for the main measurement are also designed on the reference substrate 10. During the exposure of one of the shot rows closest to the reference substrate 10 or the movement of the substrate stage between shots, the third detection system 14c causes one or more marks on the original plate and the reference plate to be exposed. It is possible to detect the overlay of marks.

  Based on the detection, the reticle thermal deformation amount at the time of exposure is calculated based on the distance between the plurality of marks or the mark position or shape variation on the original plate 1 with reference to the mark on the reference substrate 10. Processing for correcting reticle thermal deformation is performed based on the calculation result.

  Note that this effect is not limited to the above-described measurement, and is effective in various detection methods using the second position detection means 14.

  The first detection system range 14a and the second detection system range 14b are configured on a straight line including the optical axis of the projection optical system, but in the exposure region 17 or the exposure light aberration guarantee range 18, the measurement light aberration guarantee range 19, If it is desired to have a wider detection range for reasons such as improved alignment accuracy and correction of the influence of aberrations on the projection optical system, it is possible to configure it at a position away from the exposure optical axis as shown in FIG.

  In each detection system, the exposure area is changed by a masking blade (not shown) that is configured in the exposure illumination optical system. At that time, the detection systems are driven so that each detection system has a maximum detection range according to the exposure area in the focus measurement where the measurement of the exposure area is important.

  In the second exposure apparatus of the present invention, the exposure area is not a conventional rectangular type but an arc-shaped exposure area.

  As a second exposure apparatus of the present invention, for example, there is an exposure apparatus of a catadioptric projection optical system using an F2 laser as a light source.

  The second position detection means 14 configured in the second exposure apparatus of the present invention forms a detection range as shown in FIG.

  The specific shape of the detection range shown in FIG. 1 is described below.

  The exposure area of the second exposure apparatus is an area surrounded by an arc having a predetermined radius, an arc having a predetermined radius translated from the arc in the original scanning direction, and a straight line parallel to the scanning direction. The second position detection means 14 of the catadioptric exposure apparatus of the present invention comprises three or more detection systems, the first detection range 14a1 of the detection system is on the original scanning direction axis including the exposure optical axis, The second detection range 14b1 and the third detection range 14c1 are on both sides of the first detection range 14a1 with the original scanning axis including the exposure optical axis as a boundary line, and the first detection range 14a1 is the second and third detection ranges. In contrast, it is located on the convex side of the arc and on a straight line perpendicular to the original scanning direction connecting the second and third detection ranges.

  The straight line connecting the second detection range 14b1 and the third detection range 14c1 is perpendicular to the original scanning direction, and the second detection range 14b1 and the third detection range 14c1 are symmetrical with respect to the original scanning direction line including the exposure optical axis. These are arranged so that the area of the triangle having the first to third detection ranges as apex angles is maximized.

  According to the second exposure apparatus of the present invention, three or more detection systems are configured in the second position detecting means 14 in the exposure apparatus having an arc exposure area, one detection system is arranged on the convex side of the arc, By arranging two detection systems on both wings, the maximum detection range is set using the shape of the arc exposure area.

  The detection range of the second position detection means 14 is not limited to the aberration guaranteed range in which the exposure accuracy of the catadioptric projection optical system is guaranteed as shown in FIG. 1, but the accuracy and purpose required for the second position detection means 14 For example, it is possible to replace the range limited to the exposure region as shown in FIG. 16 or the projection optical system aberration guaranteed range that can guarantee the accuracy of the position measuring means.

  A detection range when each detection system 14a, 14b, 14c of the second position detection means 14 configured in the second exposure apparatus can select the detection range individually will be described.

  FIG. 17 shows a first embodiment of the detection range of the second position detecting means 14 configured in the second exposure apparatus having an arcuate exposure area.

  As shown in FIG. 17, the exposure ranges 14a1 and 14b1 constitute a detection range perpendicular to the scanning direction and a straight line detection range that can secure the maximum range in the direction perpendicular to the scanning direction in the exposure area of the projection optical system. In the first embodiment, since the driving direction of the detection system is perpendicular to the scanning direction, the optical system arrangement 14 in the second position detection means is easy, and the driving sequence is shared with the exposure apparatus whose exposure area is rectangular. Is possible depending on the conditions.

  When there are three detection systems, the detection range 14c1 of the third detection system 14c is configured to be parallel to the scanning direction and detect the center of the exposure area as shown in FIG.

  FIG. 19 shows a second embodiment of the detection range of the second position detection means 14 configured in the second exposure apparatus in which the exposure area has an arc shape.

  According to the second embodiment, as shown in FIG. 19, a drive system using an R guide or the like is configured so as to have a detection range corresponding to an arc shape, and the detection range in the exposure area is expanded from the first embodiment. doing. In the drive system of the second embodiment, the first to third detection systems are individually configured on a set of R guides, and each drive system has a drive shaft that can be driven individually. The drive shaft cannot be configured individually for each detection system due to apparatus arrangement restrictions or the like, and the detection range can be configured along an arc even with an integrated drive shaft, so that the effects of the present invention can be fully enjoyed.

  Further, the drive mechanism is not limited to the R guide or the like, and a drive mechanism in which an XY stage is mounted and the detection system can be driven in XY can be configured. Normally, the aberration of the projection optical system is designed so that the center of the exposure aberration guarantee range is minimized, so that the influence of the aberration of the projection optical system is minimized if the detection range is configured at the center of the exposure area. Alternatively, it is possible to set the detection range along a portion where the aberration of the projection optical system is small.

  FIG. 20 shows a third embodiment of the driving range of the second position detecting means 14 configured in the second exposure apparatus having an arcuate exposure area.

  According to the third embodiment, as shown in FIG. 20, the drive ranges 14a and 14b are inclined with respect to the scanning direction, and the exposure optical aberration guarantee range 18 in which the exposure accuracy of the projection optical system is guaranteed forms a linear maximum range. It is set to do.

  Alternatively, it is also useful to configure a detection range in which the influence of the aberration of the projection optical system is reduced by configuring it at the center of the approximate exposure area as shown in FIG.

  Note that the detection range of the second position detection means 14 of the exposure apparatus of the present invention is not limited to the maximum range in the exposure light aberration guarantee range 18, and according to the accuracy, purpose, etc. required for the second position detection means. It is possible to replace the measurement optical aberration guarantee range 19 in which the measurement accuracy of the two-position measurement means 14 is guaranteed, or the exposure light illumination region 17.

  For example, the drive ranges 14a and 14b in Fig. 17 are set so that the observation range is maximized in the exposure area, so the drive range is configured at a position away from the center of the projection lens, but the measurement accuracy is guaranteed. When the allowable range is allowed, a driving range sandwiching the projection lens centers can be selected as shown in FIG.

  The detection range of the second position detection unit 14 of the present invention can be set as appropriate according to the projection optical system aberration, the detection system drive range, and the component for position detection. In this case, it is possible to set a range including a plurality of elements without being limited to the above-mentioned one element, and of course, it is possible to have one element as the main and other elements as a complementary element not completely matched. It is also possible to include in a range.

FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention. 1 is a schematic bird's-eye view of a conventional first exposure apparatus. 1 is a schematic plan view of a conventional first exposure apparatus. FIG. 6 is a detection range diagram of second position detection means configured in a conventional first exposure apparatus. FIG. 2 is a schematic bird's-eye view of a conventional second exposure apparatus. FIG. 6 is a schematic plan view of a conventional second exposure apparatus. The second position detection means detection range figure comprised in the conventional 2nd exposure apparatus. FIG. 5 is a second position detection means detection range diagram configured in the first exposure apparatus of the present invention. FIG. 5 is a second position detection means detection range diagram configured in the first exposure apparatus of the present invention. FIG. 5 is a second position detection means detection range diagram configured in the first exposure apparatus of the present invention. FIG. 5 is a second position detection means detection range diagram configured in the first exposure apparatus of the present invention. FIG. 5 is a diagram showing an example of first baseline measurement in the first exposure apparatus of the present invention. FIG. 5 is a diagram showing an example of second baseline measurement in the first exposure apparatus of the present invention. FIG. 5 is a diagram showing an example of third baseline measurement in the first exposure apparatus of the present invention. FIG. 5 is a second position detection means detection range diagram configured in the first exposure apparatus of the present invention. FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention. FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention. FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention. FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention. FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention. FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention. FIG. 5 is a detection range diagram of second position detection means configured in the second exposure apparatus of the present invention.

Explanation of symbols

1 Original edition
2 Original stage
3 Laser interferometer
4 Standard version
5 Projection optics
6 Moving mirror
7 Exposure illumination optics
8 Substrate (wafer)
9 Substrate stage
10 Reference board
11 Laser interferometer
12 Moving mirror
13 First position detection means
14 Second position detection means
14a First detection system
14a1 First detection range
14b Second detection system
14b1 Second detection range
14c 3rd detection system
14c1 3rd detection range
14d1 detection range
15 Off-axis microscope
16 Off-axis microscope
17 Exposure light illumination area (exposure slit)
18 Exposure light aberration guaranteed area
19 Measurement optical aberration guaranteed area
20 Original standard mark
21 Board reference mark
22 Board reference mark
23 Microscope reference mark

Claims (6)

An exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and position detection with light having substantially the same wavelength as the exposure light via the projection optical system In an exposure apparatus having a position detection means,
2. An exposure apparatus according to claim 1, wherein the detection range of the position detection means takes a substantially maximum range in the projection optical system aberration guarantee range in which the accuracy of the position measurement means is guaranteed. An exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and position detection with light having substantially the same wavelength as the exposure light via the projection optical system In an exposure apparatus having a position detection means,
2. An exposure apparatus according to claim 1, wherein a detection range of the position detection means takes a substantially maximum range in a projection optical system aberration guarantee range in which exposure accuracy is guaranteed. An exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and position detection with light having substantially the same wavelength as the exposure light via the projection optical system In an exposure apparatus having a position detection means,
An exposure apparatus characterized in that the detection range of the position detection means takes a substantially maximum range in the exposure area of the projection optical system. An exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and position detection with light having substantially the same wavelength as the exposure light via the projection optical system In an exposure apparatus having a position detection means,
The exposure area is an area surrounded by an arc having a predetermined radius, an arc having a predetermined radius translated from the arc in the original scanning direction, and a straight line parallel to the scanning direction,
The position detection means comprises three or more detection systems,
The third detection range of the detection system is on the original scanning direction axis including the exposure optical axis,
The first detection range and the second detection range are both sides of the third detection range with the original scanning axis including the exposure optical axis as a boundary line,
The exposure apparatus characterized in that the third detection range is located on the convex side of the arc with respect to the first and second detection ranges and on a straight line that connects the first and second detection ranges and is perpendicular to the original scanning direction. . An exposure illumination optical system that illuminates the original with predetermined exposure light, a projection optical system that projects the pattern on the original onto a substrate, and position detection with light having substantially the same wavelength as the exposure light via the projection optical system In an exposure apparatus having a position detection means,
The exposure area is an area surrounded by an arc having a predetermined radius, an arc having a predetermined radius translated from the arc in the original scanning direction, and a straight line parallel to the scanning direction,
The position detection means comprises three or more detection systems,
The third detection range of the detection system is on the original scanning direction including the exposure optical axis,
The straight line connecting the first detection range and the second detection range is perpendicular to the original scanning direction,
The first detection range and the second detection range are symmetrical with respect to a straight line in the original scanning direction including the exposure optical axis.
An exposure apparatus, wherein an area of a triangle having a first to third detection range as an apex angle is a maximum.   6. The exposure apparatus according to claim 4, wherein the projection optical system is a catadioptric type.

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