JP2009010139A - Exposure apparatus and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve exposure accuracy by minimizing the residual correction of a shape of reticle surface and a shape of a wafer surface and lens aberration. <P>SOLUTION: The shape of the reticle surface, the shape of the wafer surface and the lens aberration are measured and then calculated to determine a summed surface shape based on the measured value. Accordingly, the residual correction can be minimized by adequately assigning such a summed surface shape to the drive of a reticle stage, a wafer stage, and a projection optical system for correction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exposure apparatus used for manufacturing a device such as a semiconductor device, and a device manufacturing method using the exposure apparatus.

  A projection exposure apparatus used for manufacturing a semiconductor element transfers a circuit pattern formed on an original to a photoresist layer on a substrate. For this reason, it is required to align the original plate and the substrate with high precision. Further, the miniaturization of the process is accelerated, and the exposure error (exposure residue) allowed in the apparatus becomes severe. Here, the original is a mask or a reticle, and the substrate is a semiconductor wafer or a glass plate.

  At present, reticle processing technology is improved, and reticle flatness is improved. However, since the reticle placed on the reticle stage is sucked and held by the reticle suction pad, suction deformation occurs. Due to the suction deformation, the offset caused by the reticle surface shape such as defocus and distortion cannot be ignored.

  A method for measuring the shape of the reticle surface placed on the reticle stage will be described. There is a method of measuring the reticle surface shape by continuously measuring the height of the back surface of the reticle while stepping or scanning driving the reticle stage using a grazing incidence detection type focus detection system. This method is disclosed in Patent Document 1.

  There is a method of providing a plurality of measurement marks on a reticle and measuring the positional deviation of the measurement marks with respect to the measurement optical system reference. The measurement mark is illuminated and projected onto a stage reference mark provided on the wafer stage via a projection optical system. The reticle surface shape is measured by measuring the relative positional deviation from the stage reference mark. This method is disclosed in Patent Document 2.

  A method for measuring the aberration of the projection optical system is described. A plurality of measurement marks provided on a reticle reference plate arranged at a position equivalent to the reticle is illuminated and projected onto a stage reference mark provided on a wafer stage via a projection optical system. The aberration of the projection optical system is measured by measuring the relative positional deviation (optical axis direction and horizontal direction) between the measurement mark on the reticle reference plate and the stage reference mark. This method is disclosed in Patent Document 3.

A method for measuring the wafer surface shape in the optical axis direction will be described. The wafer surface is continuously measured by stepping or scanning the wafer stage using a focus detection system of the oblique incidence detection system, and the wafer surface shape is measured. This method is disclosed in Patent Document 4.
A method for measuring the wafer surface shape in the planar direction will be described. There is so-called alignment measurement.
Each correction amount is calculated by the shape measurement, and the final correction is performed by adding all the correction amounts.
JP 2004-342900 A JP 2004-186313 A JP 2004-303830 A JP 2000-114162 A JP 2003-178968 A

At present, it is possible to measure an error amount and calculate a correction amount for each element that causes an exposure error, for high accuracy required for the apparatus. However, correction residue remains at the time of calculating the correction amount for each element. There is a need to minimize the correction residue.
An object of the present invention is to improve the adjustment accuracy of an image of an original pattern formed on a substrate.

  In order to solve the above-described problems, a first exposure apparatus according to the present invention is an exposure apparatus that exposes a substrate through an original pattern, and projects an image of the pattern by projecting light from the pattern. A projection optical system formed on the substrate, and an adjustment unit that adjusts the image of the pattern formed on the substrate, and measures each of a plurality of state quantities that determine the image of the pattern. A plurality of state quantities are added, and an adjustment amount by the adjustment unit is determined based on the added state quantities.

  A second exposure apparatus according to the present invention is an exposure apparatus that exposes a substrate through an original pattern, and projects light from the pattern to form an image of the pattern on the substrate. An optical system, a first adjustment unit that adjusts an image of the pattern formed on the substrate, and a second adjustment unit that adjusts an image of the pattern formed on the substrate, Each of the plurality of state quantities that determine the image of the pattern is measured, and at least one partial state quantity among the plurality of measured state quantities is added, and based on the added state quantity, the first quantity An adjustment amount by the adjustment unit is determined, and an amount obtained by subtracting the adjustment amount by the first adjustment unit from the added state amount is added to the remaining state amount among the plurality of measured state amounts. , Based on the added amount, the adjustment by the second adjustment unit. To determine the amount, and wherein the.

  According to the present invention, for example, the adjustment accuracy of an image of an original pattern formed on a substrate can be improved.

In a preferred embodiment of the present invention, the present invention is an exposure apparatus that exposes a substrate through an original pattern, and projects light from the pattern to form an image of the pattern on the substrate Applicable to an optical system.
The exposure apparatus according to the first embodiment of the present invention includes an adjustment unit that adjusts an image of the pattern formed on the substrate. Then, each of a plurality of state quantities that determine the image of the pattern is measured, the plurality of measured state quantities are added, and an adjustment amount by the adjustment unit is determined based on the added state quantities.

Here, the original plate is, for example, a mask or a reticle, and the substrate is, for example, a semiconductor wafer or a glass plate.
The adjustment unit performs at least one of driving an optical element in the projection optical system, driving an original stage holding the original, and driving a substrate stage holding the substrate.
Further, the plurality of state quantities include at least one of a shape of the original plate (original plate surface shape), a shape of the substrate (substrate surface shape), and a shape of the image plane of the projection optical system (projection optical system image surface shape). Includes two. Hereinafter, the projection optical system image surface shape is also referred to as lens aberration or projection optical system surface shape.
As a specific example, reticle surface shape (original plate shape), wafer surface shape (substrate surface shape), and lens aberration are measured, and reticle surface shape, wafer surface shape, and lens aberration are calculated based on the measured values to obtain a comprehensive image. The correction residue is minimized by obtaining and correcting the surface shape or the total surface shape.

  An exposure apparatus according to a second embodiment of the present invention includes a first adjustment unit that adjusts an image of the pattern formed on the substrate, and a first adjustment unit that adjusts the image of the pattern formed on the substrate. 2 adjustment units. Then, each of a plurality of state quantities that determine the image of the pattern is measured, and at least one partial state quantity among the plurality of measured state quantities is added, and based on the added state quantity, An adjustment amount by the first adjustment unit is determined. Further, an amount obtained by subtracting the adjustment amount by the first adjustment unit from the added state amount and the remaining state amount among the plurality of measured state amounts are added, and based on the added amount The amount of adjustment by the second adjustment unit is determined.

Here, the first adjustment unit performs a part of driving of an optical element in the projection optical system, driving of an original stage holding the original, and driving of a substrate stage holding the substrate.
The second adjustment unit performs another part of driving of the optical element in the projection optical system, driving of the original stage holding the original, and driving of the substrate stage holding the substrate.
The plurality of state quantities include at least two of the shape of the original plate, the shape of the substrate, and the shape of the image plane of the projection optical system.

  As a specific example, an original plate surface shape measuring unit for measuring the surface shape of the reticle, a substrate surface shape measuring unit for measuring the surface shape of the wafer, and a projection optical system image surface shape for measuring the aberration of the projection optical system Measuring means. Further, a shape calculating means for calculating a reticle surface shape, a wafer surface shape, and a lens aberration based on the measurement values measured by the original surface shape measuring means, the substrate surface shape measuring means, and the projection optical system image surface shape measuring means. Have. A correction residue calculation unit that calculates a correction residue based on the correction amount calculated by the correction amount calculation unit and the shape calculated by the shape calculation unit with respect to at least one shape. Correction residue correction amount calculation means for calculating a second correction amount based on a correction residue shape calculated by adding all of the correction residues calculated by the correction residue calculation means or the correction residue and the correction amount of another shape; Have. Correction method selection means for determining a correction item and a correction method based on the correction amount calculated by the correction amount calculation means and the correction residue correction amount calculation means, and the correction item and correction selected by the correction method selection means It has a correction means which corrects by a method.

  Here, the correction items include, for example, correction of the primary and secondary components of the reticle surface shape, correction of the primary and secondary components of the wafer surface shape, and correction of the primary and secondary components of the projection optical system image surface shape. . Further, for example, in the case of a scanning exposure apparatus, the correction method is a scanning direction in the Y direction, and the optical axis (Z) direction of the original or substrate during scanning of the original and the substrate and around the scanning axis (X tilt). Drive and drive in the optical axis direction of the projection optical system. The surface shape is, for example, a surface shape in the optical axis direction of the projection optical system and a surface shape in a direction perpendicular to the optical axis direction.

Hereinafter, embodiments of the present invention will be described more specifically.
The reticle surface shape is measured by an off-axis autofocus optical system and a TTR observation optical system. Wafer surface shape measurement is performed using an off-axis autofocus optical system and an off-axis alignment observation optical system. In the projection optical system aberration measurement, measurement by the TTR observation optical system is performed. Hereinafter, the projection optical system aberration may be referred to as a projection optical system surface shape or a projection optical system surface shape.

FIG. 1 is a block diagram showing the arrangement of an exposure apparatus to which the present invention can be applied.
In FIG. 1, reference numeral 1 denotes a light source for exposure such as a lamp, a laser, or EUV light. When the circuit pattern on the reticle is transferred and exposed onto the wafer, an instruction from the exposure apparatus control system 70 is transmitted to the light source control system 30, and the operation of the exposure light source 1 is controlled by the instruction from the light source control system 30.

Reference numeral 2 denotes a reticle, which is held on the reticle stage 4. Although not shown, the reticle 2 is provided with a plurality of measurement marks.
Reference numeral 3 denotes a reticle reference plate, which is held by the reticle stage 4 in FIG. 1, but is optically fixed at a position equivalent to the reticle. Although not shown, a plurality of reticle reference marks are provided on the reticle reference plate 3.

  In the scanning exposure apparatus, the reticle stage 4 is movable in the optical axis direction (Z direction) of the projection optical system 5 and in the XY direction (here, horizontal direction) perpendicular to the optical axis, and is rotated with respect to the optical axis. Is also possible. In the drive control of the reticle stage 4, an instruction from the exposure apparatus control system 70 is transmitted to the reticle stage control system 40, and the reticle stage 4 is driven and controlled by an instruction from the reticle stage control system 40.

  The projection optical system 5 is composed of a plurality of lenses, and at the time of exposure, a circuit pattern on the reticle is imaged on the wafer 8 at a magnification corresponding to the reduction magnification of the projection optical system 5. Although the projection optical system 5 is not shown, an aberration correction optical system is provided.

  Reference numerals 6 and 7 form an off-axis autofocus measurement system. Reference numeral 6 denotes a light projecting optical system, and a light beam that is non-exposure light emitted from the light projecting optical system 6 is focused on a point on the stage reference plate 9 (or the upper surface of the wafer 8) and reflected. The reflected light beam enters the detection optical system 7. Although not shown, a position detection light-receiving element is disposed in the detection optical system 7 so that the position detection light-receiving element and the reflection point of the light beam on the stage reference plate 9 are conjugate. The positional deviation of the stage reference plate 9 with respect to the projection optical system 5 in the optical axis direction is measured as the positional deviation of the incident light beam on the position detection light receiving element in the detection optical system 7.

  The positional deviation of the stage reference plate 9 from the predetermined reference plane measured by the detection optical system 7 is transmitted to the wafer stage control system 60. During focus calibration measurement, the wafer stage control system 60 drives the stage reference plate 9 up and down in the optical axis direction (Z direction) of the projection optical system 5 in the vicinity of a predetermined reference position. In addition, the position control of the wafer 8 is also performed during exposure.

  The TTR observation optical system 20 includes a fiber 21, a half mirror 22, an objective lens 23, a mirror 24, and an image sensor 25. The illumination light beam emitted from the fiber 21 passes through the half mirror 22 and is condensed near the reticle reference plate 3 (or reticle 2) via the objective lens 23 and the mirror 24. The illumination light beam condensed near the reticle reference plate 3 is condensed on the stage reference plate 9 via the projection optical system 5. The reflected light from the stage reference plate 9 returns to the original optical path, and is reflected by the half mirror 22 through the projection optical system 5, reticle reference plate 3, mirror 24, and objective lens 23 in order, and enters the image sensor 25. Although not shown, a relay lens that changes the focal position with respect to the observation surface is configured in the TTR observation optical system 20. Although not shown, a plurality of TTR observation optical systems 20 are arranged in the X direction of the reticle stage 4.

  Reference numeral 11 denotes a TTR observation optical system (hereinafter referred to as a sensor). The illumination light beam from the light source 1 or the TTR observation optical system 20 illuminates the reticle mark arranged on the reticle 2 or the reticle reference plate 3 and is projected onto the stage reference plate 9 via the projection optical system 5. Although not shown, a slit having the same size as the projected mark is formed on the stage reference plate 9, and the light transmitted through the slit reaches the sensor 11. The sensor 11 is a light amount integrating sensor. When the relative position of the projected mark and the light receiving slit changes, the light amount received by the sensor changes. Measurement by the sensor 11 is performed by utilizing this phenomenon. By moving the stage 10 in the measurement direction with the reticle mark illuminated, the amount of light becomes maximum (or minimum) when the projected mark and the slit coincide. The relative position between the reticle mark and the stage reference plate is obtained from the relationship between the position of the stage 10 and the amount of light.

  Reference numerals 81 and 82 form an off-axis autofocus optical system. Reference numeral 81 denotes a light projecting optical system. A light beam, which is non-exposure light emitted from the light projecting optical system 81, is condensed on a point on the lower surface 2a of the reticle 2 or the reticle reference plate 3 and reflected. The reflected light beam enters the detection optical system 82. Although not shown, a position detection light-receiving element is disposed in the detection optical system 82, and the position detection light-receiving element and the reflection point of the light beam projected onto the lower surface 2a of the reticle 2 are configured to be conjugate. Yes. The positional deviation in the optical axis direction between the lower surface 2 a of the reticle 2 and the projection optical system 5 is measured as the positional deviation of the incident light beam on the position detection light receiving element in the detection optical system 82. The deviation in the optical axis direction from the predetermined reference surface or reference position of the reticle 2 measured by the detection optical system 82 is transmitted to the reticle surface control system 80.

  Reference numeral 90 denotes an off-axis alignment optical system. Although not shown, the off-axis alignment optical system includes a light source, an image sensor, and the like.

  The measurement of the reticle surface shape placed on the reticle stage 4 will be described. Here, FIGS. 2 and 3 are views showing the relationship of the measurement system for measuring the position of the reticle 2, the reticle suction pad 42, and the reticle lower surface 2a on the reticle stage 4 with respect to the projection optical system 5 in the optical axis direction.

  FIG. 2 shows the positional relationship between the reticle 2 and the reticle suction pad 42 when the reticle 2 is sucked onto the reticle stage 4. As shown in FIG. 2, the suction pads 42 are arranged at the four corners outside the actual element pattern area of the reticle 2. Although not shown, since the reticle stage 4 can be scanned and driven in the Y direction in the figure, the pads 42 at the four corners are also configured to be long in the scanning direction.

FIG. 3 is a schematic cross-sectional view showing a state in which the reticle 2 is adsorbed on the reticle stage 4. The positional relationship of the measurement system (81a, 82a, 81b, 82b, 81c, 82c) which measures the height of the reticle 2 and the reticle suction pad 42 and the reticle lower surface 2a in the optical axis direction with respect to the projection optical system 5 is shown. As shown in FIG. 3, the measurement system is arranged at a position where the measurement beam does not interfere with the suction pad 42 and in a region where the X direction of the reticle can be measured over a wide range.
In this embodiment, the height of the reticle lower surface 2a can be measured at three points in the X direction. However, any number of measurement systems may be arranged in the X direction as long as the measurement beam does not interfere.

Hereinafter, height measurement in the Z direction with respect to the projection optical system 5 on the reticle lower surface 2a will be described.
Here, FIG. 4 is a schematic plan view showing the measurement point MP. In FIG. 4, black circles indicate measurement points. The height of the reticle lower surface 2a with respect to the projection optical system 5 in the optical axis direction is measured at each position by moving the reticle stage 4. Regarding measurement, the reticle stage 4 may be driven to scan, and each measurement point during the scan drive may be continuously measured, or the reticle stage 4 may be driven to each measurement point position and measured in a stationary state. Good. When measuring each measurement point MP with higher accuracy, the measurement may be performed in a stationary state, and when the measurement time is shortened, each measurement point during scanning driving may be continuously measured.

The measurement of the shape of the reticle surface placed on the reticle stage 4 by the TTR observation optical system 20 will be described. Here, FIG. 5 is a plan view showing the relationship between the reticle 2, the reticle suction pad 42 and the reticle mark 44 on the reticle stage 4.
In FIG. 5, the reticle mark 44 is not arranged in the actual element pattern area, but the reticle mark 44 may be arranged in the actual element pattern area.

  Hereinafter, measurement of the optical axis direction of the reticle mark 44 with respect to the projection optical system 5 will be described. Here, FIG. 6 is a measurement sequence flow for measuring the in-focus position of the TTR observation optical system 20 with respect to the reticle mark 44. The flowchart shown in FIG. 6 is stored in the storage unit in the control system 70. A program or software that implements such a flowchart also constitutes one aspect of the present invention.

The reticle stage 4 is driven to the first reticle mark 44 in step S0 in FIG. At this time, the objective lens 23 of the TTR observation optical system 20 has already been driven to a position where the first reticle mark 44 can be observed.
In step S1, the relay lens of the TTR observation optical system 20 is driven to the measurement start position.

  In step S2, the reticle mark 44 is measured by the TTR observation optical system 20. When the sensor used in the TTR observation optical system 20 is a photoelectric conversion element, the amount of light reflected from the mark is the measurement value, and when the sensor is a two-dimensional sensor represented by a CCD, the contrast of the mark is measured. Value.

  In step S3, it is confirmed whether the measurement for the number of measurement points necessary for calculating the in-focus position of the TTR observation optical system 20 with respect to the reticle mark 44 is completed. If the measurement necessary for calculating the in-focus position is not completed, the focus position of the relay lens is changed in step S4. Thereafter, mark measurement is performed in step S2. When the measurement for the number of measurement points necessary for calculating the in-focus position of the TTR observation optical system 20 with respect to the reticle mark 44 is completed in step S3, the in-focus position is calculated and stored in step S5. Next, in step S6, it is confirmed whether all marks have been measured.

If all the marks have not been measured, the reticle stage 4 is driven to the next reticle mark 44 in step S7. In step S7, in the case of a stepper (collective exposure apparatus) where the movable range of the reticle stage 4 is narrow, the objective lens 23 of the TTR observation optical system 20 may be driven to the mark observation position.
By repeating steps S0 to S7 until all the marks have been measured, the in-focus position (MP) of the reticle mark 44 relative to the TTR observation optical system 20 can be obtained.

  The optical axis direction measurement with the TTR observation optical system 20 has been described above. After the in-focus position of each mark is obtained, the relay lens is driven to the in-focus position of the reticle mark, and the measurement of the reticle mark position is obtained to complete the horizontal measurement.

The positional deviation of the reticle mark relative to the TTR observation optical system may be used as the measurement value, or the reticle mark and the stage reference mark may be observed simultaneously with the TTR observation optical system, and the relative positional deviation between the reticle mark and the stage reference mark may be used as the measurement value. .
The configuration of the TTR observation optical system may be a configuration in which the reticle mark is illuminated with an exposure light source and the amount of light transmitted through the slit provided on the stage reference mark is measured for the projected image.

  A method of performing reticle surface shape measurement using an off-axis autofocus optical system and a TTR observation optical system will be described. In the measurement by the off-axis autofocus optical system, the surface shape in the optical axis direction of the reticle surface with respect to the projection optical system is measured by the method described above. In this measurement, measurement is performed in a state where the reticle is attracted to the reticle stage and in a state where the reticle is deactivated. The reason for performing the measurement with suction ON / OFF is that the purpose is to measure the difference in the reticle surface shape due to suction ON / OFF.

  In the measurement by the TTR observation optical system, the optical surface direction and horizontal surface shape of the reticle surface with respect to the projection optical system are measured by the above-described method. The measurement here is also performed by suction ON / OFF. The configuration of the TTR observation optical system may be either a mark irradiation method using a dedicated fiber or a mark irradiation method using an exposure light source.

Let (x, y) be the measurement coordinates in the reticle, (on) be the measurement value when suction is ON, and (off) be the measurement value when suction is OFF. Further, the suction ON / OFF difference measured by the off-axis autofocus optical system is expressed as ΔZ1 (x, y) = Z1 (on) −Z1 (off) (Formula 1)
And Further, the adsorption ON / OFF difference measured by the TTR observation optical system is expressed as follows: ΔZ2 (x, y) = Z2 (on) −Z2 (off) (Formula 2)
ΔX2 (x, y) = X2 (on) −X2 (off) (Formula 3)
ΔY2 (x, y) = Y2 (on) −Y2 (off) (Formula 4)
And Then, an optical axis direction and a horizontal relational expression are obtained from the results of (Expression 2), (Expression 3), and (Expression 4).

  As for the relational expression, an approximate surface may be obtained from the measurement values of all points, or a coefficient may be obtained for each measurement point. The relational expression may be obtained separately for the optical axis direction approximate surface and the plane direction approximate surface, or may be a function of the optical axis direction position and the plane direction position.

Next, the sensitivity of the off-axis autofocus optical system and the TTR observation optical system is obtained from the results of (Expression 1) and (Expression 2).
For the sensitivity, an approximate function may be obtained from the measurement values at all points, or a coefficient may be obtained for each measurement point. The sensitivity may be obtained separately for the optical axis direction approximate surface and the plane direction approximate surface, or may be a function of the optical axis direction position and the plane direction position.

  As described above, the horizontal position with respect to the projection optical system can be calculated based on the measurement result of the off-axis autofocus optical system by obtaining the relationship between the optical axis direction and the planar direction and the sensitivity due to the difference in the measurement system. It becomes possible.

Next, the measurement of the shape of the wafer surface placed on the wafer stage 10 will be described.
FIG. 7 is a diagram showing the wafer 8 and the exposure area in the wafer 8. The exposure area in the wafer 8 is divided into a plurality of areas.
FIG. 8 shows the positions of the exposure region 800 in the wafer 8 and the off-axis autofocus measurement systems 6 and 7. In FIG. 8, the off-axis autofocus measurement systems 6 and 7 are configured to measure only one point with respect to the exposure region 800. However, if the measurement beam does not interfere, the number of optical systems is arranged in the X and Y directions. You may do it.

  In the optical axis direction surface shape measurement of the surface of the wafer 8, the wafer stage 10 is driven to the measurement position of the off-axis autofocus measurement systems 6 and 7 to measure the surface of the wafer 8. The measurement may be performed on the entire surface of the wafer 8, or when the exposure area 800 is known as shown in FIG. 7, only the exposure area 800 may be measured.

  As for the measurement method, measurement may be performed while the wafer stage 10 is stationary and then driven to the next measurement position, and measurement may be repeated while the wafer stage 10 is stationary. Alternatively, the wafer stage 10 may be scanned and driven. Alternatively, the surface of the wafer 8 during scanning driving may be measured.

9 and 10 show the measurement points when the off-axis autofocus measurement systems 6 and 7 measure the surface shape of the wafer 8 in the optical axis direction.
FIG. 9 shows measurement points when the entire surface of the wafer 8 is measured. When the surface shape measurement in the direction of the optical axis of the entire surface of the wafer 8 is performed, the local surface shape of the surface of the wafer 8 can be calculated based on the measurement values of the entire surface of the wafer 8, so that the wafer surface shape measurement can be performed with high accuracy. Can be implemented.

FIG. 10 shows measurement points when only the exposure area of the wafer 8 is measured. When the surface shape measurement in the optical axis direction for only the exposure region is performed, the surface shape for each exposure region can be measured. Further, since the measurement area is narrower than the measurement of the entire surface of the wafer 8, the measurement is completed in a short time.
When measuring the surface shape of the wafer 8 in the optical axis direction with higher accuracy, more off-axis autofocus optical systems may be arranged, or measurement may be performed at more measurement points on the wafer.

  Next, planar surface shape measurement of the wafer 8 will be described. The plane direction surface shape measurement of the wafer 8 may be performed by so-called alignment measurement. In the alignment measurement, a positional deviation of the alignment mark drawn on the wafer 8 with respect to the off-axis alignment optical system 90 is measured.

  The planar surface shape of the wafer 8 can be separated into the planar surface shape of the entire wafer and the planar surface shape of the exposure region. FIG. 11 is a diagram showing a sample shot 800 s for performing alignment measurement on the wafer 8 and an exposure area in the wafer 8. Here, the sample shot is an exposure region in which an alignment mark for performing alignment measurement is drawn in the exposure region 800.

  FIG. 11 shows that when the inside of the wafer 8 is divided by the X axis and the Y axis with respect to the center of the wafer 8 and divided into the first to fourth quadrants, each quadrant is separated from the center of the wafer 8 by a certain distance or more. An existing exposure area 800 is a sample shot 800s. Although the number of sample shots 800 s is four in the present embodiment, at least three sample shots are sufficient to obtain the planar surface shape of the wafer 8. In order to obtain the planar surface shape of the wafer 8 with higher accuracy, the number of sample shots may be increased.

  12 and 13 are diagrams showing sample shots. In FIG. 12, an alignment mark (black dots in the figure indicate alignment marks) is drawn near the center of the sample shot. In FIG. 13, alignment marks are drawn at the four corners of the sample shot.

  The planar surface shape of the wafer 8 can be obtained by measuring the alignment marks in FIG. 12 by the number of sample shots in FIG. 11 and calculating the horizontal surface shape with respect to the projection optical system based on the measured values. Here, the planar shape of the wafer 8 includes wafer shift, wafer magnification, wafer orthogonality, and wafer rotation.

  By measuring the alignment mark in FIG. 13, it is possible to calculate the planar surface shape of the exposure region. Here, the planar surface shape of the exposure region includes shift, magnification, orthogonality, rotation, and distortion. In the present embodiment, the number of alignment marks is four. However, if it is desired to obtain the planar surface shape of the exposure region with higher accuracy, the number of alignment marks may be increased.

Up to this point, a description has been given of the so-called single stage embodiment in which one wafer stage 10 is configured in the apparatus.
FIG. 14 is a view when two wafer stages 10 are arranged in the apparatus. The two wafer stages 10 are movable under the projection optical system 5 and under the off-axis autofocus measurement systems 6 and 7 (and the off-axis alignment optical system 90). The configuration is the same as in FIG. 1 except that two wafer stages 10 are configured and the off-axis autofocus measurement systems 6 and 7 do not have measurement points directly under the projection optical system 5. Omitted.

The off-axis autofocus measurement systems 6 and 7 and the off-axis alignment optical system may be disposed under the projection optical system 5. In this case, the offsets of the two off-axis autofocus optical systems and off-axis alignment optical systems may be measured in advance.
Two projection optical systems, two off-axis autofocus optical systems, and two off-axis alignment optical systems may be provided. In this case, the offsets of the two projection optical systems, the off-axis autofocus optical system, and the off-axis alignment optical system may be measured in advance.

  In the apparatus configuration of FIG. 14, exposure processing is performed under the projection optical system 5, and wafer surface shape measurement in the optical axis direction and planar direction of the wafer 8 is performed under the off-axis autofocus measurement systems 6 and 7 and the off-axis alignment optical system 90. Can be processed in parallel. Therefore, since the wafer surface shape measurement can be performed until the exposure processing is completed, the number of measurement points can be increased, and a more detailed measurement result can be obtained.

FIG. 15 is a flowchart showing a processing sequence of the exposure processing on the two wafer stages 10.
In step S10, the wafer stage 10 is driven to the exposure position. The exposure position is a position below the projection optical system 5 in a so-called stepper, and a position away from the bottom of the projection optical system 5 by a distance required for constant speed driving in a so-called scanner (scanning exposure apparatus).
In step S15, an exposure process is performed. The exposure process is performed in units of one exposure area on the wafer 8.

  In step S20, the completion of the exposure process for all exposure areas is confirmed. If the exposure process is not completed, the next exposure position is calculated and the process returns to step S10. When the exposure process is completed, the process ends. Although not shown in FIG. 15, after the exposure process is completed, the wafer 8 is collected, and the wafer for which the measurement process of FIG. 16 is completed is subjected to the exposure process according to the exposure process sequence flow of FIG.

The measurement process is performed in parallel with the exposure process of FIG.
FIG. 16 is a processing sequence flow of measurement processing by a wafer stage 10 different from the wafer stage 10 of FIG.

  In step S50, focus measurement is performed. The focus measurement is a surface shape measurement of the wafer 8 in the optical axis direction by the above-described off-axis autofocus measurement systems 6 and 7. As for the measurement method, the wafer stage is scanned and driven with respect to the off-axis autofocus optical system, and the optical axis direction measurement of the wafer 8 being scanned is performed. Alternatively, the wafer stage is driven under the off-axis autofocus optical system, the measurement is performed in a state where the wafer stage is stationary, and then the operation is repeated to drive to the next measurement position. As a result, it is only necessary to measure the position in the optical axis direction of the entire wafer surface or the entire exposure region shown in FIG.

  In step S55, a focus map is created. The focus map is created based on the optical axis direction measurement value at the plane position (X, Y position) on the wafer 8. The map may be a map of the entire wafer or a map for each exposure region. A correction amount in the optical axis direction may be calculated and used as a map.

  In step S60, the wafer stage is driven to a position where alignment measurement is performed. Here, the position where the alignment measurement is performed may be only the sample shot shown in FIG. 11 and the alignment mark shown in FIG. 12, or all the exposure regions shown in FIG. 11 and the alignment mark shown in FIG. All alignment marks drawn on the wafer 8 may be measured.

  In step S65, alignment marks are measured. Here, the alignment mark is measured in accordance with the focus map created in step S55 to obtain the position of the alignment mark to be measured in the optical axis direction. After driving the wafer stage to the obtained position in the optical axis direction, the planar position measurement is performed. As another method, the alignment mark is driven in the optical axis direction, the light amount or contrast is measured by the off-axis alignment optical system, and the focal position is obtained based on the change in the light amount or contrast measurement value with respect to the position in the optical axis direction. . Thereafter, the planar position measurement may be performed after the stage is driven to the in-focus position.

In step S70, the misalignment amount of the alignment mark is calculated. The amount of misalignment is determined as the amount of exposure that each alignment mark exposed on the wafer is shifted from the design coordinates.
In step S75, it is confirmed whether all the alignment measurements scheduled for measurement have been completed. If there is an unmeasured mark, the position of the next alignment mark is calculated, and the process returns to step S60. When all the alignment mark measurements are completed, the measurement ends.

  After all the measurements are completed, an alignment map is created in step S80. The alignment map uses a relative relationship of the deviation amount in the actual coordinates with respect to the design coordinates. The map may be a map of the entire wafer or a map for each exposure region. A correction amount in the plane direction may be calculated and used as a map.

The sequence flow of FIGS. 15 and 16 has been described. In an apparatus in which two wafer stages are mounted as shown in FIG. 14, the exposure process and the measurement process are performed in parallel.
In addition to the apparatus configuration of FIG. 14, if the surface shape of the wafer or the exposure area in the optical axis direction and the plane direction is determined in advance, and the configuration is such that the surface shape is notified to the exposure apparatus before exposure processing, the inside of the apparatus It is not necessary to configure two wafer stages.

  FIG. 17 is a diagram showing the optical axis direction surface shape measurement position on the wafer measured by the measurement sequence flow of FIG. The surface shape in the optical axis direction is characterized in that there are measurement points not only on the entire exposure area on the wafer and in the exposure area but also on the outer periphery and in the vicinity of the exposure area. When scanning exposure is performed, there are almost steps in the optical axis direction in the vicinity of the exposure area and in the outer periphery and the exposure area. Therefore, since it is important to know the shape of the neighborhood in advance, measurement points are provided on the outer periphery and the neighborhood.

  FIG. 18 is a diagram showing planar surface shape measurement positions on the wafer measured by the measurement sequence flow of FIG. The planar surface shape is characterized in that there are measurement points in the exposure area on the wafer. In the case of measuring in the plane direction, the alignment mark is already printed by exposure, and the mark is measured.

Next, the aberration measurement of the projection optical system 5 will be described. As a method for measuring the wavefront aberration of the projection optical system, the method disclosed in Patent Document 5 can measure the aberration of the projection optical system 5 with the highest accuracy. However, this method takes time because exposure processing and measurement processing are required to obtain the wavefront aberration.
The aberration measurement of the projection optical system in the present embodiment will be described with respect to simple aberration measurement by the TTR observation optical system.

FIG. 19 and FIG. 20 show a sequence flow of the surface shape measurement in the optical axis direction of the projection optical system by the TTR observation optical system.
FIG. 19 shows a sequence flow of the surface shape measurement in the optical axis direction of the projection optical system by the TTR observation optical system 20.

In step S100, the relay lens in the TTR observation optical system is driven to the measurement start position. Although not shown, the objective lens is also driven as preparation for measurement.
In step S105, the reticle side mark is measured. In this measurement, the mark contrast with respect to the position in the optical axis direction of the relay lens with respect to the projection optical system is measured.

In step S110, it is confirmed whether measurement of the reticle side mark is completed. If the measurement has not been completed, the optical axis direction position of the relay lens is changed in step S115, and the process returns to step S105.
The measurement of the reticle side mark in step S105 is performed to align the focal position of the TTR observation optical system with the reticle side mark. The previously measured in-focus position may be stored, and the measurement process may be omitted if the stored in-focus position does not change.

In step S120, the relay lens is driven to the in-focus position of the reticle side mark.
In step S125, the wafer side mark is driven to the measurement position.
In step S130, the wafer side mark is measured. In this measurement, the mark contrast with respect to the position in the optical axis direction of the relay lens with respect to the projection optical system is measured.

In step S135, it is confirmed whether measurement of the wafer side mark is completed. If the measurement is not completed, the position of the wafer stage in the optical axis direction is changed in step S140, and the process returns to step S130.
In step S145, the optimum focus position is calculated based on the measured position in the optical axis direction of the wafer stage and the mark contrast at each position.

Although not shown, when a plurality of TTR observation optical systems are configured, the optimum focal position measurement at a plurality of locations in the projection optical system is completed by the sequence flow of FIG.
When the optimum focus position measurement of the projection optical system is performed with high accuracy, the objective lens of the TTR observation optical system may be driven to measure a plurality of locations in the projection optical system.

FIG. 20 shows a sequence flow of the surface shape measurement in the optical axis direction of the projection optical system by the TTR observation optical system 11.
In step S150, measurement preparation is performed. Here, the measurement preparation refers to driving of a light shielding plate for limiting an irradiation area of illumination light with respect to the reticle side mark, or driving to a measurement position of a wafer stage on which a light quantity integrating sensor is mounted.

In step S155, measurement is performed while driving the wafer stage in the optical axis direction. In the measurement, since the illumination light is pulsed like a laser, the position in the optical axis direction of the stage at the time of pulse emission and the amount of light integrated at that time are stored.
In step S160, the optimum focal position is calculated based on the measured position in the optical axis direction of the wafer stage and the light quantity at each position.

Although not shown, when a plurality of TTR observation optical systems are configured, the optimum focal position measurement at a plurality of positions of the projection optical system is completed by the sequence flow of FIG.
When the optimum focus position measurement of the projection optical system is performed with high accuracy, the light shielding plate is driven in accordance with the reticle mark each time, the wafer stage is driven to the measurement position, and a plurality of positions are measured.

  In the present embodiment, the configuration in which the reticle side mark is illuminated by the exposure light source has been described, but the reticle side mark may be illuminated by the TTR observation optical system 20.

FIG. 21 and FIG. 22 show a sequence flow of measuring the planar surface shape of the projection optical system by the TTR observation optical system.
FIG. 21 shows a sequence flow of measuring the planar surface shape of the projection optical system by the TTR observation optical system 20.

In step S200, the relay lens of the TTR observation optical system is driven to the in-focus position with respect to the reticle side mark.
In step S205, the wafer side mark is driven to the in-focus position.

  The in-focus position in steps S200 and S205 may be the in-focus position obtained in FIG. As another method, the focus position of the wafer-side mark may be measured after obtaining the focus position of the relay lens with respect to the reticle mark by the sequence flow of FIG. 19 for the mark to be measured. Steps S200 and S205 are driven in parallel processing.

In step S210, planar position measurement is performed. In the planar position measurement, the reticle side mark and the wafer side mark are simultaneously observed by the TTR observation optical system, and the positional deviation amount between the reticle side mark and the wafer side mark with respect to the TTR observation optical system is measured.
In step S215, the planar position is calculated. For the position in the plane direction, a relative positional deviation amount between the reticle side mark and the wafer side mark at the measurement image height of the projection optical system is calculated.

Although not shown, when a plurality of TTR observation optical systems are configured, the planar position measurement at a plurality of positions of the projection optical system is completed by the sequence flow of FIG.
When measuring the position in the planar direction of the projection optical system with high accuracy, the objective lens of the TTR observation optical system may be driven to measure a plurality of locations in the projection optical system.

FIG. 22 shows a sequence flow of measuring the planar surface shape of the projection optical system by the TTR observation optical system 11.
In step S250, measurement preparation is performed. Here, the measurement preparation refers to driving of a light shielding plate for limiting an irradiation area of illumination light with respect to the reticle side mark, or driving to a measurement position of a wafer stage on which a light quantity integrating sensor is mounted.

In step S255, measurement is performed while driving the wafer stage in the plane direction. In the measurement, since the illumination light is pulsed like a laser, the position in the plane direction of the stage at the time of pulse emission and the amount of light integrated at that time are stored.
In step S260, the amount of positional deviation in the planar direction with respect to the design coordinates is calculated based on the measured planar position of the wafer stage and the amount of light at each position.

Although not shown, when a plurality of TTR observation optical systems are configured, the planar direction position measurement at a plurality of positions of the projection optical system is completed by the sequence flow of FIG.
When measuring the position in the plane direction of the projection optical system with high accuracy, the light shielding plate is driven in accordance with the reticle mark each time, the wafer stage is driven to the measurement position, and a plurality of positions are measured.

In the present embodiment, the configuration in which the reticle side mark is illuminated by the exposure light source has been described, but the TTR observation optical system 20 may illuminate the reticle side mark.
As described above, the optical axis direction surface shape and the planar direction surface shape of the reticle, the optical axis direction surface shape and the planar direction surface shape of the wafer, and the optical axis direction surface shape and the planar direction surface shape of the projection optical system can be respectively obtained. I can do it.

[First embodiment]
As a first example of the present invention, correction to the surface shape is performed based on the optical axis direction surface shape of the reticle obtained in the above embodiment, the optical axis direction surface shape of the wafer, and the optical axis direction surface shape of the projection optical system. A method for determining items and correction methods will be described.

FIG. 23 shows the shape of the reticle in the optical axis direction. It can be seen that the reticle is bent in the Z direction (optical axis direction).
FIG. 24 shows items that can be corrected by the apparatus with respect to the shape of the reticle in the optical axis direction in FIG. 23 (in this embodiment, the position in the optical axis direction: Z, the tilt in the X direction: tilt X, and the curvature of field component). The correction amount is shown.

FIG. 25 shows a correction residue (correction residue) obtained by subtracting the correction amount of FIG. 24 from the optical axis direction surface shape of the reticle of FIG.
As described above, even if the surface shape of the reticle in the optical axis direction is measured with high accuracy and correction is performed, the residue cannot be made zero.

FIG. 26 shows the surface shape in the optical axis direction of the projection optical system. It can be seen that the projection optical system is bent in the Z direction (optical axis direction).
FIG. 27 shows items that can be corrected by the apparatus with respect to the shape in the optical axis direction of the projection optical system in FIG. 26 (in this embodiment, the position in the optical axis direction: Z, the tilt in the X direction: tilt X, and the curvature of field component). The amount of correction is shown.

FIG. 28 shows the remaining correction obtained by subtracting the correction amount of FIG. 27 from the surface shape in the optical axis direction of the projection optical system of FIG.
As described above, even when the surface shape in the optical axis direction of the projection optical system is measured with high accuracy and correction is performed, the residue cannot be made zero.

FIG. 29 shows the surface shape in the optical axis direction of the exposure region in the wafer. It can be seen that the exposure area has a complicated shape.
FIG. 30 shows items that can be corrected by the apparatus with respect to the surface shape in the optical axis direction of the exposure region in FIG. 29 (optical axis direction position: Z, tilt in X direction: tilt X, field curvature component in this embodiment). The amount of correction is shown.

FIG. 31 shows a residual correction obtained by subtracting the correction amount of FIG. 30 from the surface shape in the optical axis direction of the exposure region of FIG.
As described above, even when the surface shape in the optical axis direction of the exposure area is measured with high accuracy and correction is performed, the residue cannot be made zero.

  FIG. 32 shows the residue in the shape of the optical axis direction surface obtained by adding the correction residues in FIGS. 25, 28 and 31 described above. The surface shape of the reticle, projection optical system, and exposure area in the direction of the optical axis can be measured with high accuracy, and even if the correction amount is calculated and corrected individually, the residue cannot be reduced to zero. The correction residue is about ± 10 nm in the exposure region.

  On the other hand, FIG. 33 shows a total image surface shape obtained by adding the surface shapes in the optical axis direction of FIG. 23, FIG. 26 and FIG. The total image surface shape refers to a surface shape that is obtained by adding the optical axis direction measurement values of the reticle, wafer (exposure area), and projection optical system at the same plane direction position (X, Y coordinates). The total image plane shape represents the image plane shape when exposure is performed. Therefore, the correction residue can be reduced by correcting the total image plane shape.

FIG. 34 shows the correction amount in the items that can be corrected by the apparatus (in this embodiment, the position in the optical axis direction: Z, the tilt in the X direction: tilt X, and the curvature of field component) with respect to the total image plane shape in FIG. Show.
FIG. 35 shows a residual correction obtained by subtracting the correction amount shown in FIG. 34 from the total image plane shape shown in FIG. As shown in FIG. 35 and FIG. 32, the remaining correction is small. In FIG. 32, the correction residue that is about ± 10 nm in the exposure area is reduced to about ± 3 nm in the exposure area in FIG.

  As described above, when the reticle, projection optical system, and exposure area surface shape in the optical axis direction are measured with high accuracy before exposure, it is better to obtain the total image surface shape from each component and perform correction. Correction residue can be reduced.

  A correction item and a correction method will be described. The primary components (Z and tilt X, tilt Y) are obtained from the total image surface shape obtained as described above. In the case of a scanning exposure apparatus, Z and tilt X may be calculated as the correction amount by calculating the primary component for each scanning direction (Y direction) coordinate in the exposure area on the wafer. As a correction method, the wafer stage or the reticle stage may be corrected and driven in the Z direction and the tilt X direction during scanning driving according to the correction amount. If the control position during scanning drive of the wafer stage or reticle stage and the measurement position of the total image plane shape are different, an approximate function is obtained in advance based on the total image plane shape, and the control position during scan driving is given to the approximate function. The correction amount may be calculated. In the case of a batch exposure apparatus, the primary component may be calculated as a correction amount by calculating a primary plane (Z and tilt X, tilt Y) for each exposure area on the wafer. As a correction method, the wafer stage or the reticle stage may be corrected and driven in the Z direction and the tilt X and tilt Y directions according to the correction amount.

  Next, the primary component obtained as described above is subtracted from the total image plane shape. A secondary component is obtained from the total image plane shape after subtraction. In the case of a scanning type exposure apparatus, a secondary component may be calculated for each scanning direction in the on-wafer exposure area and used as a correction amount. The correction method may be correction driving by synchronizing the secondary component with scanning driving in the projection optical system. If the correction drive of the projection optical system cannot be synchronized with the scan drive, the average value of the secondary component calculated for each exposure area is calculated, and the secondary component is corrected and driven by the projection optical system before exposure for each exposure area. It ’s fine. In the case of the batch exposure apparatus, the secondary component is calculated from the measurement value at the measurement position where the Y coordinate is the same as the measurement value in the exposure area on the wafer, and the average value of the calculated secondary component may be used as the correction value. . As a correction method, the secondary component may be corrected and driven by the projection optical system before exposure for each exposure region.

[Modification of the first embodiment]
As another method, the primary component and the secondary component are calculated based on the reticle, wafer (exposure region), and the shape of the projection optical system in the optical axis direction. Each correction residue is added, and the total image plane shape of the correction residue is calculated. The primary component and the secondary component may be calculated based on the calculated total image plane shape. Since the correction method has been described above, it will be omitted.

  In the first embodiment, the surface shapes in the optical axis direction of the reticle, wafer, and projection optical system are all added. However, if the reticle stage and wafer stage can be independently corrected and driven in the optical axis direction, the following method is used. The surface shape may be calculated.

  The primary component and the secondary component are calculated from the surface shape in the optical axis direction of the reticle. Based on the calculated correction amount, correction driving by the reticle stage is performed. The correction residue of the reticle is added to the surface shape in the optical axis direction of the projection optical system and the exposure area to calculate the total image surface shape. The primary component and the secondary component may be calculated based on the calculated total image plane shape. Since the correction method has been described above, it will be omitted.

  In this embodiment, the primary component and the secondary component are corrected. However, there is a correction method in which correction driving is not performed when the correction amount is small. This is because after the correction amount is calculated and the correction means is determined, the correction resolution of the correction means is compared with the correction amount. If the correction amount is equal to or less than the correction resolution, the correction error increases.

[Effect of the first embodiment]
By executing the correction amount calculation, the correction means determination, and the correction, the correction residue can be minimized.

[Second Embodiment]
As a second example of the present invention, correction items and corrections for the surface shape based on the planar surface shape of the reticle, the planar surface shape of the wafer, and the planar surface shape of the projection optical system obtained by the above embodiment. A method for determining the method will be described.

  FIG. 36 shows the planar surface shape of the reticle. A thin line indicates an ideal planar shape. A black dot indicates a measured value, and a thick line connecting the black dots indicates a planar surface shape of the reticle obtained from the measured value.

FIG. 37 shows the remaining correction after the planar surface shape of the reticle of FIG. 36 is corrected. Compared to FIG. 36, it is close to the ideal planar shape, but it can be seen that there is a residue.
As described above, even when the planar surface shape of the reticle is measured with high accuracy and corrected, the residue cannot be made zero.

  FIG. 38 shows the planar surface shape of the projection optical system. A thin line indicates an ideal planar shape. A black dot indicates a measured value, and a bold line connecting the black dots indicates a planar surface shape of the projection optical system obtained from the measured value.

FIG. 39 shows the remaining correction after correcting the planar surface shape of the projection optical system of FIG. Compared to FIG. 30, it is close to the ideal planar shape, but it can be seen that there is a residue.
As described above, even if the planar surface shape of the projection optical system is measured with high accuracy and corrected, the residue cannot be made zero.

  FIG. 40 shows the planar shape of the exposure area in the wafer. A thin line indicates an ideal planar shape. A black dot indicates a measured value, and a thick line connecting the black dots indicates a planar surface shape of the wafer obtained from the measured value.

FIG. 41 shows the remaining correction after the planar surface shape of the exposure region in FIG. 40 is corrected. Compared to FIG. 40, it is close to the ideal planar shape, but it can be seen that there is a residue.
As described above, even when the planar surface shape of the exposure area is measured with high accuracy and correction is performed, the residue cannot be made zero.

  FIG. 42 shows a planar surface shape residue obtained by adding the correction residues in FIGS. 37, 39, and 41 described above. As can be seen from FIG. 42, the optical axis direction of the reticle, the projection optical system, and the exposure area can be measured with high accuracy, and a residue is generated even if the correction amount is calculated and corrected individually. The correction residue is about ± 4 nm in the exposure region.

  On the other hand, FIG. 43 shows an overall planar shape obtained by adding the planar direction surface shapes of FIGS. 36, 38 and 40. The total planar shape refers to a surface shape obtained by adding the planar direction measurement values of the reticle, wafer (exposure area), and projection optical system at the same planar direction position (X, Y coordinates). The total plane shape represents the image plane shape when exposure is performed. Therefore, the correction residue can be reduced by correcting the total planar shape.

  FIG. 44 shows the remaining correction after the total planar shape of FIG. 43 is corrected. The correction residue is reduced to ± 1.9 nm in the exposure area.

  A correction item and a correction method will be described. A primary component (X and Y magnification), a tertiary component (X and Y distortion), and an offset (X and Y shift) are obtained from the overall planar shape obtained as described above. In the case of a scanning exposure apparatus, a correction amount may be obtained for each scanning direction (Y direction) in the on-wafer exposure region. As an offset correction method, the wafer stage or the reticle stage may be corrected and driven in the X direction and the Y direction during the scanning drive according to the correction amount. When the control position during scanning driving of the wafer stage or the reticle stage is different from the measurement position of the total plane shape, an approximate function is obtained in advance based on the total plane shape. Thereafter, the correction amount may be calculated by giving a control position during scanning driving to the obtained approximate function. As a correction method of the primary and tertiary components, the primary and tertiary components may be corrected and driven in synchronization with the scanning drive in the projection optical system. If the correction drive of the projection optical system cannot be synchronized with the scan drive, the average value of the primary and tertiary components calculated for each exposure area may be calculated, and correction drive may be performed by the projection optical system before exposure for each exposure area.

  In the case of a collective exposure apparatus, the correction amount may be calculated by calculating the primary, tertiary, and offset for each exposure area on the wafer. As an offset correction method, the wafer stage or the reticle stage may be corrected and driven in the X direction and the Y direction according to the correction amount. In the primary and tertiary component correction methods, the primary and tertiary component correction amounts calculated for each exposure region may be corrected and driven by the projection optical system before exposure for each exposure region.

[Modification of Second Embodiment]
As another method, the offset, the primary component, and the tertiary component are calculated based on the plane direction surface shape of the reticle, wafer (exposure region), and projection optical system, respectively. Each correction residue is added and the total planar shape of the correction residue is calculated. The offset, the primary component, and the tertiary component may be calculated based on the calculated overall planar shape. Since the correction method has been described above, it will be omitted.

  In the second embodiment, the planar surface shapes of the reticle, wafer, and projection optical system are all added. However, if the reticle stage and the wafer stage can be independently corrected and driven in the planar direction, the surface shape is obtained by the following method. May be calculated.

  An offset and a primary component are calculated from the planar surface shape of the reticle. Based on the calculated correction amount, correction driving by the reticle stage is performed. Here, the primary component to be corrected by the reticle stage is only the magnification component in the scanning direction (Y direction). The correction residue of the reticle is added to the planar direction surface shape of the projection optical system and the exposure area to calculate the total planar shape. The offset, the primary component, and the tertiary component may be calculated based on the calculated overall planar shape. Since the correction method has been described above, it will be omitted.

  In this embodiment, the offset, the primary component, and the tertiary component are corrected. However, there is a correction method in which correction driving is not performed when the correction amount is small. This is because after the correction amount is calculated and the correction means is determined, the correction resolution of the correction means is compared with the correction amount. If the correction amount is equal to or less than the correction resolution, the correction error increases.

[Effect of the second embodiment]
By executing the correction amount calculation, the correction means determination, and the correction, the correction residue can be minimized.

[Example of device manufacturing method]
Next, with reference to FIGS. 45 and 46, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. FIG. 45 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, a semiconductor chip manufacturing method will be described as an example.
In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask production), a mask (also referred to as an original plate or a reticle) is produced based on the designed circuit pattern. In step 3 (wafer manufacture), a wafer (also referred to as a substrate) is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer using the mask and the wafer by the above exposure apparatus using the lithography technique. Step 5 (assembly) is referred to as a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4. including. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, a semiconductor device is completed and shipped (step 7).

  FIG. 46 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus to expose the wafer through the pattern formed on the mask. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer.

It is a block diagram of the exposure apparatus which concerns on one Embodiment of this invention. It is a top view which shows the relationship between the reticle in the apparatus of FIG. 1, and a reticle suction pad. FIG. 3 is a cross-sectional view showing the relationship between the reticle, the reticle suction pad, and the reticle lower surface measurement oblique incidence measurement system in FIG. 2. FIG. 3 is a schematic plan view showing measurement points MP on the lower surface of the reticle in FIG. 2. FIG. 3 is a plan view showing the relationship between a reticle, a reticle suction pad, and a reticle mark in FIG. 2. 6 is a measurement sequence flow of a focal position of the TTR observation optical system with respect to the reticle mark of FIG. 5. It is a top view which shows the relationship between a wafer and the exposure area | region arrangement | positioning in a wafer. It is a top view which shows the relationship between the exposure area | region of FIG. 7, and arrangement | positioning of an off-axis auto-focus optical system. It is a top view which shows an example of the wafer of FIG. 7, an exposure area | region in a wafer, and an off-axis autofocus measurement point. FIG. 8 is a plan view illustrating another example of the wafer, the in-wafer exposure area, and the off-axis autofocus measurement point in FIG. 7. It is a top view which shows the relationship between a wafer, the exposure area | region in a wafer, and sample shot arrangement | positioning. It is a top view which shows an example of alignment mark arrangement | positioning in a sample shot. It is a top view which shows the other example of alignment mark arrangement | positioning in a sample shot. It is a block diagram of the exposure apparatus which comprised two wafer stages based on other embodiment of this invention. 15 is an exposure processing sequence flow in the exposure apparatus of FIG. 15 is a measurement processing sequence flow in the exposure apparatus of FIG. It is a top view which shows the optical axis direction surface shape measurement position on a wafer. It is a top view which shows the planar direction surface shape measurement position on a wafer. It is a processing sequence flow of the optical axis direction surface shape measurement of a projection optical system. It is a processing sequence flow of the optical axis direction surface shape measurement of a projection optical system. It is a processing sequence flow of planar direction surface shape measurement of a projection optical system. It is a processing sequence flow of planar direction surface shape measurement of a projection optical system. It is a figure which shows the optical axis direction surface shape of a reticle. It is a figure which shows the optical axis direction surface shape correction amount of a reticle. It is a figure which shows the optical axis direction surface shape correction | amendment residue of a reticle. It is a figure which shows the optical-axis direction surface shape of a projection optical system. It is a figure which shows the optical axis direction surface shape correction amount of a projection optical system. It is a figure which shows the optical axis direction surface shape correction | amendment residue of a projection optical system. It is a figure which shows the optical axis direction surface shape of the exposure area | region in a wafer. It is a figure which shows the optical axis direction surface shape correction amount of the exposure area | region in a wafer. It is a figure which shows the optical axis direction surface shape correction | amendment residue of the exposure area | region in a wafer. It is a figure which shows all the correction residues of an optical axis direction. It is a figure which shows a comprehensive image surface shape. It is a figure which shows the total image surface shape correction amount. It is a figure which shows the correction | amendment residue after total image surface shape correction | amendment. It is a figure which shows the planar direction surface shape of a reticle. It is a figure which shows the planar direction surface shape correction | amendment of a reticle. It is a figure which shows the planar direction surface shape of a projection optical system. It is a figure which shows the planar direction surface shape correction | amendment residue of a projection optical system. It is a figure which shows the planar direction surface shape of the exposure area | region in a wafer. It is a figure which shows the plane direction surface shape correction | amendment of the exposure area | region in a wafer. It is a figure which shows all the correction | amendment residues of a plane direction. It is a figure which shows a comprehensive planar shape. It is a figure which shows the correction | amendment residue after total plane shape correction | amendment. It is a flowchart for demonstrating manufacture of the device using an exposure apparatus. 46 is a detailed flowchart of the wafer process in Step 4 in the flowchart shown in FIG. 45. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Reticle 3 Reticle reference plate 4 Reticle stage 5 Projection optical system 6 Wafer side off-axis autofocus measurement system (light projection optical system)
7 Wafer side off-axis autofocus measurement system (detection optics)
8 Wafer 9 Stage reference plate 10 Wafer stage 11 TTR observation optical system (sensor)
20 TTR observation optical system 40 reticle stage control system 50 projection optical system control system 60 wafer stage control system 70 exposure apparatus control system 80 reticle surface control system 81 reticle side off-axis autofocus optical system (projection optical system)
82 Reticle side off-axis autofocus optical system (detection optical system)
90 Off-axis alignment optical system

Claims (8)

An exposure apparatus that exposes a substrate through an original pattern,
A projection optical system that projects light from the pattern to form an image of the pattern on the substrate;
An adjustment unit for adjusting an image of the pattern formed on the substrate;
Have
Measure each of a plurality of state quantities that determine the pattern image,
Add the measured state quantities,
An adjustment amount by the adjustment unit is determined based on the added state amount.
An exposure apparatus characterized by that.   The adjustment unit performs at least one of driving an optical element in the projection optical system, driving an original stage holding the original, and driving a substrate stage holding the substrate. 2. The exposure apparatus according to 1.   The exposure apparatus according to claim 1, wherein the plurality of state quantities include at least two of a shape of the original plate, a shape of the substrate, and a shape of an image plane of the projection optical system. . An exposure apparatus that exposes a substrate through an original pattern,
A projection optical system that projects light from the pattern to form an image of the pattern on the substrate;
A first adjustment unit for adjusting an image of the pattern formed on the substrate;
A second adjustment unit for adjusting an image of the pattern formed on the substrate;
Have
Measure each of a plurality of state quantities that determine the pattern image,
Adding at least one partial state quantity among the plurality of measured state quantities;
Based on the added state quantity, an adjustment amount by the first adjustment unit is determined,
Adding the amount obtained by subtracting the adjustment amount by the first adjustment unit from the added state amount and the remaining state amount among the measured state amounts;
Based on the added amount, an adjustment amount by the second adjustment unit is determined.
An exposure apparatus characterized by that.   The first adjustment unit performs a part of driving an optical element in the projection optical system, driving an original stage holding the original, and driving a substrate stage holding the substrate. The exposure apparatus according to claim 4.   The second adjustment unit performs another part of driving of an optical element in the projection optical system, driving of an original stage holding the original, and driving of a substrate stage holding the substrate. 6. An exposure apparatus according to claim 5, wherein   The plurality of state quantities include at least two of the shape of the original plate, the shape of the substrate, and the shape of the image plane of the projection optical system. Exposure equipment. Exposing the substrate using the exposure apparatus according to claim 1;
Developing the exposed substrate;
A device manufacturing method comprising:

Images