JP2006135055A - Exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure apparatus which can prevent the lowering of throughput without degrading accuracy as much as possible by controlling timing of preceding processing optimally. <P>SOLUTION: The aligner is provided with a method for alignment where the surface of an object adjacent to an image formation surface of a projection optical system is focused on the focal point of the projection system by using a positional detection means for detecting the plane position on the surface of the object. In this case, the timing of preceding processing prior to alignment is controlled to obtain a setting value that is set in advance during alignment and is necessary to detect the optimal focus surface of the object. Thus, throughput can be improved without affecting measuring accuracy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stepper that repeatedly reduces and exposes a circuit pattern on a reticle onto a substrate surface in the field of semiconductor element manufacturing, a projection exposure apparatus called a scanner, a projection exposure method using the projection exposure apparatus, and a device manufacturing method. In particular, it is suitable for detecting the surface position such as the height and inclination of the surface of an object in which a region having a pattern structure such as a wafer is formed in the manufacture of a semiconductor device, and enables highly accurate detection. The present invention relates to an exposure apparatus.

  Recent progress in semiconductor device manufacturing technology is remarkable, and the progress of microfabrication technology is also remarkable. In particular, the optical processing technology has been mainly reduced projection exposure equipment with a submicron resolution, commonly called a stepper, and the numerical aperture (NA) has been increased and the exposure wavelength has been shortened to improve resolution. Yes.

  Further, in order to enlarge the exposure area, a reduction scanning projection exposure apparatus (scanning exposure apparatus) composed of a lens system or a lens system and a mirror system has become mainstream.

  In this scanning-type reduction projection exposure apparatus, a stage on which a reticle having a circuit pattern is placed and a stage on which a wafer for pattern transfer is placed are relative to each other at a speed ratio corresponding to the reduction magnification of the projection optical system. Exposure is performed while scanning.

  In general, if the NA is increased to increase the resolution of the projection optical system, the allowable depth of focus for pattern projection is reduced, and the accuracy requirement for aligning the wafer surface with the in-focus position of the projection optical system becomes severe.

  2. Description of the Related Art Conventionally, in a reduction projection type exposure apparatus for manufacturing a semiconductor device, a surface position detection apparatus prior to projecting and exposing a circuit pattern of a reticle as a first object onto a wafer as a second object by a projection lens system. The position of the wafer surface in the optical axis direction is detected using (autofocus device, AF device), and the wafer surface is positioned at the best image plane of the projection lens.

  As a surface position detection mechanism for a wafer surface used in a projection exposure apparatus, a detection mechanism configured by making a light beam incident obliquely on the wafer surface is generally used. In this detection mechanism, a plurality of light beams are irradiated onto the wafer surface, which is the surface to be inspected, and the plurality of light beams reflected from the wafer surface are received by the photoelectric conversion elements, respectively, and the incident position of the light beams on the photoelectric conversion elements Information on the position of the wafer surface in the Z direction (focus), and information on the surface of the wafer surface, such as detecting tilt information (tilt) of the wafer surface from the focus information of a plurality of measurement points. Is measured.

  Here, in the surface position detection mechanism using the oblique incidence optical system, the surface position detection accuracy deteriorates if the reflectance of the detection surface fluctuates and the light reception signal is too large or conversely too small to deteriorate the S / N. Therefore, it is necessary to adjust (light control) the irradiation light amount of the light projecting means and the gain of the light receiving means according to the reflectance of the detection surface during exposure. Therefore, by shortening or uniformizing the time for dimming to make the surface position measurement time constant, and measuring the reflectance of the area to be measured in advance to improve the surface position detection accuracy, the measurement cycle There is a method of managing a certain amount (see, for example, Patent Document 1).

  Further, in the above detection method, in order to reliably position the entire exposed area of the wafer within the allowable depth of focus of the pattern projection which has become shallower due to the increase in NA, a pattern on the wafer is previously measured at each of a plurality of measurement points. Measure the pattern step (topography) in the area, determine the difference in the measured value due to the topography of each of the multiple measurement points, and then transfer each pattern to the exposure area on the wafer. This is achieved by correcting the difference between the measured values and the measured values caused by the topography.

In such a surface position detection mechanism, the local pattern step (topography) and reflectance of the detection surface vary depending on the pattern formed on the detection surface. Therefore, in general, the above pre-processing (hereinafter referred to as pre-processing) performed for improving the surface position detection accuracy is performed at regular intervals before exposure such as wafer replacement. In addition, in order to improve and stabilize the surface position detection accuracy and improve the throughput, such a preceding process is generally performed in a plurality of processes such as the dimming process and the topography measurement described above. is there.
Japanese Patent Laid-Open No. 10-064980

  By the way, when these processes are periodically performed before exposure, there is a problem that the time required for the preceding process causes a reduction in throughput. In particular, in the recent semiconductor industry, the focus has shifted to a small variety of products such as high-value-added system-on-chip (SOC). As a result, the proportion of time required for the preceding process has increased, and a reduction in throughput due to this has become a major problem. In order to eliminate this, it is desirable to reduce the preceding process as much as possible, but if it is simply reduced, the following problems occur.

  That is, since the amount of light emitted from the light projecting means and the gain adjustment (dimming) of the light receiving means are not sufficiently performed, the measurement time required for the surface position measurement and the surface position measurement accuracy vary, and in synchronization with the servo system. A response delay occurs, or an error caused by topography in the pattern area cannot fit the entire exposed area of the wafer within the allowable depth of focus of pattern projection.

  Therefore, when the focus (height and tilt) of the wafer surface is measured so as not to deteriorate the accuracy without reducing the throughput and the wafer surface is kept within the allowable depth of focus, It is necessary to perform an advance measurement process before exposure at an appropriate timing and accurately measure an offset necessary for correction. However, the timing of performing these prior processes is currently managed empirically, and cannot be said to be optimized for each process.

  The present invention has been made in view of such problems, and provides an exposure apparatus and method capable of minimizing throughput reduction without degradation in accuracy by optimally managing the timing of performing the preceding process. To do.

  In order to solve the above-described problem, in the present invention, an object plane provided in the vicinity of the image plane of the projection optical system is used as a position detection unit that detects a surface position on the object plane, and the focus of the projection optical system is In the exposure method for focusing on the surface, in order to obtain a setting value necessary for detection of the optimal focus surface of the object surface that is set in advance at the time of exposure, the timing of the preceding processing execution that is executed in advance prior to exposure, The determination is made based on information obtained in a preceding processing sequence different from the same performed immediately before or before.

  According to a preferred embodiment of the present invention, the preceding process includes a process for adjusting the amount of measurement light for detecting the surface position of the object plane, and exposure of a pattern step (topography) on the object plane. In the preceding process such as the process for measuring the difference between the measured values caused by the topography and managing the offset due to the topography, it is possible to reduce the execution opportunity of the preceding process including at least one without causing deterioration in accuracy. .

  According to a preferred embodiment of the present invention, the timing of the preceding process execution includes, for example, an elapsed time during the exposure in which parameters can be arbitrarily set, the total number of exposures of the object to be exposed, the total number of exposures, and an error during exposure. This is determined based on at least one of the conditions given by the occurrence rate or the change in reflectance of the object to be exposed calculated during execution of other processing.

  According to a preferred embodiment of the present invention, the object plane provided in the vicinity of the imaging plane of the projection optical system is used with position detection means for detecting the position of the surface above the object plane, and the projection optical system In the exposure method for focusing on the focal plane, the correction amount based on the result of the preceding process during the next exposure or the preceding amount is obtained based on the information obtained during the previous measurement value or other processes without performing the preceding process again. It is characterized in that at least one item of the parameter for determining the process re-execution timing can be corrected.

  If the above means is used, the preceding process is performed at an optimal timing, and the focus (height and tilt) of the wafer surface is measured so that the accuracy is not deteriorated without reducing the throughput, and the wafer surface is within the allowable depth of focus. It is possible to perform the focus correction held in

  According to the present invention, it is possible to reduce the measurement opportunity of the preceding process, which has been performed at a fixed interval before exposure, such as at the time of exchanging the wafers, without degrading the accuracy of the semiconductor device as compared with the prior art. Productivity can be improved. Data used for dimming and offset management is corrected and updated as needed from the reflectance change and light quantity data measured during the exposure process. For this reason, the light control processing of the exposed area, offset correction, etc. are always performed with high accuracy, and the product defect rate can be reduced.

  Hereinafter, embodiments of the invention will be described with reference to the drawings.

  FIG. 4 is a schematic view of a step-and-scan projection exposure apparatus having a surface position detection mechanism using an oblique incidence optical system according to an embodiment of the present invention. In FIG. 4, reference numeral 1 denotes a projection lens system, and its optical axis is indicated by AX in the drawing. The projection lens system 1 projects a circuit pattern of a mask such as a reticle (not shown) with a reduction of, for example, 1/4 times, and forms a circuit pattern on the focal plane. Further, the optical axis AX has a parallel relationship with the Z-axis direction in the drawing. Reference numeral 2 denotes a wafer having a surface coated with a resist, on which a plurality of exposed areas (hereinafter referred to as shots) in which the same pattern is formed in the previous exposure process are arranged.

  Reference numeral 3 denotes a wafer stage on which the wafer 2 is mounted. The wafer 2 is attracted and fixed to the wafer stage 3. The wafer stage 3 is rotated around an X stage that moves in the X axis direction, a Y stage that moves in the Y axis direction, a movement in the Z axis direction, and an axis parallel to the X axis direction, the Y axis direction, and the Z axis direction. It consists of a Θ tilt stage. Further, the X axis, the Y axis, and the Z axis are installed so as to be orthogonal to each other. Therefore, this exposure apparatus adjusts the surface position of the wafer 2 in the direction along the optical axis AX direction of the projection lens system 1 and the plane orthogonal to the optical axis AX by driving the wafer stage 3, and further the focal plane. That is, the inclination with respect to the circuit pattern image is also adjusted.

  The displacement of the wafer stage 3 in the X-axis and Y-axis directions is measured by a known method using a reference mirror and a laser interferometer provided on the wafer stage 3, and a signal indicating the displacement amount of the wafer stage 3 is laser interference. The total is input to the control device 13 via a signal line. The movement of the wafer stage 3 is controlled by the stage driving device 12, and the stage driving device 12 receives a command signal from the control device 13 through the signal line, and servo-drives the wafer stage 3 in response to this signal. ing.

  The stage driving device 12 has a first driving means and a second driving means, and the position (X, Y) and rotation (Θ) in a plane orthogonal to the optical axis AX of the wafer 2 by the first driving means. The position (Z) and the inclination (WX, WY) of the wafer 2 in the optical axis AX direction are adjusted by the second driving means.

  In the case of scanning reduction projection exposure, the exposure light beam is formed in a slit shape, and both the reticle stage (not shown) and the wafer stage 3 are set in accordance with the optical magnification of the projection optical system with respect to the slit exposure light beam. This is performed by moving the pattern transfer region on the reticle and the pattern transfer region on the wafer 2 with respect to the fixed slit-shaped exposure light beam by moving in one direction at a speed ratio.

  Next, the surface position detection mechanism of this embodiment will be described. Reference numerals (4 to 14) in FIG. 4 indicate the elements of the detection means provided for detecting the surface position and inclination of the wafer 2. The surface position detection apparatus for detecting the surface position information of the wafer surface 2 shown in FIG. 4 shows only one measurement point detection means for the sake of simplification, but actually projects a plurality of detection points, The tilt amount of the test surface is calculated from the focus information at the measurement points. Reference numeral 4 denotes an illumination light source, for example, a light source with high brightness such as a light emitting diode or a semiconductor laser. Reference numeral 5 denotes an illumination lens.

  The light emitted from the light source 4 becomes a parallel light beam by the illumination lens 5 and illuminates the slit plate 6. A plurality of apertures are provided on the slit plate 6, and a plurality of light beams (61 to 65) that have passed through the apertures of the slit plate 6 are incident on the folding mirror 8 through the joint lens 7. After changing the direction, the light is incident on the surface of the wafer 2. Here, the imaging lens 7 and the bending mirror 8 form an image of a plurality of openings of the slit 6 on the wafer 2.

  FIG. 5 shows a shot arrangement on the wafer 2, and FIG. 6 shows, for example, a shot 100 when scanning each shot, a slit (exposure slit) 30 projected onto the wafer 2 by the projection optical system, and the surface of the wafer 2 The change of the positional relationship with a plurality of upper measurement points (hereinafter referred to as CH) is shown. In the case of the present embodiment, in order to properly use the measurement points according to the direction of scanning exposure (B direction or F direction), each CH has five positions (50b to 54b, 50b to 54b, 50 f to 54 f) and five (50 to 54) in total at the center of the exposure slit 30 are set. A light beam for surface position measurement emitted from the light source 4 corresponding to the number of CHs is irradiated to each of these CHs from an oblique direction. For example, in the case of scanning exposure in the F direction, surface position measurement is performed in advance at five measurement points (50f to 54f) before reaching the exposure position, and further, these five focus values and known values are known in advance. The amount of inclination is calculated from the positional relationship of the measurement points.

  In order to prevent the deterioration of accuracy due to the light receiving signal being too large and the light receiving system being saturated or conversely being too small and the S / N being deteriorated, the amount of light to be irradiated here is set in advance before the surface position detection. The light beam from the light projecting means is incident on each detection point, the reflected light is received by the light receiving means, and the drive current of the light projecting means or the gain of the light receiving means in each CH based on the light reception signal. By finding the optimal value of, the time for dimming during scan measurement is shortened or integrated, the surface position measurement time during scanning is made constant, and the surface position detection is synchronized with the scan for offset measurement. Is accurately performed to improve the surface position detection accuracy (preceding process 1).

  Similarly, in the case of scanning exposure in the B direction, the surface position is measured in advance at the measurement points (50b to 54b), and the amount of inclination is calculated from the focus values of these five points and the positional relationship between known measurement points in advance. is doing.

  The surface position detection device 14 performs processing based on an output signal (surface position data) from the position detection element 11 and detects the position of the surface of the wafer 2. Then, the detection result is transferred to the control device 13, and a command is sent to the stage drive device 12 by a predetermined command signal, and the desired focus and tilt amount are driven before reaching the exposure position.

  Further, in order to detect the deviation of the position (Z) and the inclination (WX, WY) with respect to the position in the Z direction of the exposure area of the wafer 2, that is, the image plane position, the surface of the wafer 2 is accurately corrected. There must be. Therefore, prior to exposure, Z, WX, and WY are measured in advance under the condition that the focus value is measured with the highest accuracy, and the height of the portion requiring the highest focus accuracy in the exposed area is used as a reference. Japanese Patent Application No. 9-045608 proposes that the detection error of the focus measurement value measured during the scan exposure can be corrected in real time by managing the offset (preceding process 2).

  Further, reference numeral (17-20) in FIG. 4 denotes a detection means provided for detecting the position of the alignment mark 24 formed on the wafer 2 in the alignment of the pattern on the wafer 2 and the pattern on the reticle. Each element is shown. Reference numeral 18 denotes a light source for illumination, for example, a light source with high brightness such as an emitting diode or a semiconductor laser. The light emitted from the light source 18 changes its direction by the half mirror 17 and then illuminates the alignment mark 24 on the wafer 2 via the projection lens system 1. The light reflected on the wafer 2 enters the position detection element 19 again via the projection lens system 1 and the half mirror 17. The position detection element 19 includes a two-dimensional CCD or the like, and outputs an image including the alignment mark 24 to the alignment mark position detection device 20. The alignment mark position detection device 20 calculates the alignment mark position from the position of the stage 3 and the detection position of the alignment mark 24. Prior to the start of exposure, the control device 13 sequentially moves the stage 3 to a position where each alignment mark can be measured from the shot layout information, alignment mark arrangement information, and measurement mark selection information, and the alignment mark position detection device 20. The detection position is received from. Then, the precise positional relationship between the shot arrangement on the wafer and the projection pattern of the reticle is obtained from the relationship between the reticle position and stage position measured in advance, the shot layout information, and the alignment mark detection position information, and at the time of step-and-repeat Used for shot alignment (global alignment).

  Next, an exposure processing method according to a preferred embodiment of the present invention will be described with reference to flowcharts FIG. 1, FIG. 2, and FIG.

  First, when exposure of a certain lot is started (step 100), in step 101, a lot leading wafer is selected.

  Next, in step 102, the control device 13 starts from the alignment mark position detection device 20 arranged on each sample shot (S01 to S04) as shown in FIG. 5 based on the sample shot information set in advance. Receives the detection position and performs global alignment.

  For each preceding process, the preceding process execution determination unit 150 changes the determination method for the preceding process re-execution from information obtained during processing such as measurement performed before the preceding process. In the first embodiment, the information obtained at the time of the global alignment in step 102 is used to determine whether to re-execute the preceding process 1 (the dimming process for the measured light amount: Japanese Patent Laid-Open No. 10-64980) performed in the subsequent step 103. Used.

  Therefore, at this time, each sample shot (S01 to S04) and the reflectance during movement between sample shots are received from the surface position detection device 14 by the timing management unit 170 provided in the control device 13 and recorded in the database. In the present embodiment, the amount of reflected light including the movement of the sample shots S01 → S02 of the global alignment given in FIG. 5, the amount of reflected light including the movement of S02 → S03, and the amount of reflected light including the movement of S03 → S04 are respectively shown. Record. The database unit monitors the rate of change from the amount of reflected light at the previous measurement.

  When the change rate exceeds a preset threshold value (threshold value a), the preceding process execution determination unit 150 determines that the measurement dimming value for the surface position measurement has changed, and restarts the preceding process. Set the execution judgment flag. If this rate of change exceeds a preset threshold value (threshold value b), the re-measurement of the preceding process itself is not performed, and the correction value recorded in the database is changed, for example, by the amount of reflected light from the previous time. If it is increased, the measured light quantity is reduced according to the amount of change, and if the reflected light quantity is reduced, the measured light quantity is rewritten so as to be increased according to the amount of change.

  FIG. 9 shows the transition of the reflected light amount difference recorded in the database at a certain point P between the sample shots S01 → S02. In FIG. 9, the number of measurements exceeds the threshold value a at the time of the (i + 4) th global alignment measurement, and at this time, it is determined to re-execute the preceding process.

  In the above description, the value of the database is rewritten, but when the threshold value b is exceeded, a determination flag for re-execution of the preceding process is set, and according to the amount of change obtained at this time, The dimming value of the object surface may be predicted to reduce the time required for the measurement of the preceding process 1 or determine the validity of the result of the preceding process 1.

  Next, in order to measure the surface position at a plurality of points in the exposed area, the measurement light at the time of exposure proposed in Japanese Patent Laid-Open No. 10-64980 by the timing management unit 170 provided in the control device 13 is used. It is determined (step 103) whether or not to perform the dimming process (preceding process 1) for detecting the optimum light quantity.

  The timing management unit 170 analyzes the data currently recorded in step 151. Here, it is determined by the flowchart of FIG. In FIG. 7, a determination is made based on the conditions indicated in steps 301 to 305, and if all the conditions are satisfied, a determination is made in step 306 that the preceding process is not executed.

  If at least one of the conditions indicated in steps 301 to 305 is not satisfied, a determination is made in step 307 to re-execute the preceding process.

  If it is determined in the preceding process 1, remeasurement is performed in step 152, and the result is recorded in the database in step 153.

  Next, in step 104, focus offset measurement for offset management of surface position information proposed in Japanese Patent Application No. 9-045608 is performed.

  When the correction value necessary for detecting the surface position during exposure is obtained, the control device 13 then accurately calculates the position of the exposed region using the laser interferometer 16 and uses the stage driving device 12 to determine the position of the stage 3. After positioning, exposure processing is started (step 105).

  In the exposure process of step 105, the light amount incident on each measurement point on the exposure area using the surface position detection device 14 while referring to the data measured in the preceding process 1 or the dimming value recorded in the database. Adjust. Then, from the surface position information measured by the surface position detection device 14 and the focus offset measured in step 104, the positional deviation amount between the exposure area and the imaging surface of the projection lens system 1 is calculated, and the stage driving device 12 is used. Then, exposure is performed while the stage 3 is driven.

  FIG. 2 shows an outline of a preceding process timing management unit provided in the control device 13 in the present embodiment. In step 102 and step 104, when the advance processing determination is instructed (160), the data analysis unit 161 analyzes the data recorded in the database 162. In the data analysis unit 161, according to the flowchart shown in FIG. 7, whether an error has occurred in step 301, whether a specified time has passed in step 302, specified number of sheets has been processed in step 303, or monitored in step 103. If at least one of the conditions given by the light amount data at the time of global alignment (step 304) and the threshold value a of the wafer reflectivity change amount (step 305) is not satisfied, the remeasurement opportunity of the preceding process is determined at step 307. To do. When the re-measurement determination is made, the preceding process is executed again, and the database value is updated based on the measurement result reflected during exposure.

  After the above processing is performed on all the wafers in the lot, the exposure lot is exchanged in step 106, and when all the lots are completed, the exposure is terminated.

  In the first embodiment, the reflected light amount information that can be acquired at the time of the global alignment in step 103 is used for the determination of the previous process remeasurement or the correction of the correction value registered in the database. Similar processing may be performed from information that can be acquired during other processing, such as the amount of reflected light.

  Next, an exposure processing method according to the second embodiment of the present invention will be described with reference to flowcharts FIG. 3, FIG. 7, and FIG.

  First, when exposure of a certain lot is started (step 200), in step 201, a lot leading wafer is selected.

  Next, in step 202, the control device 13 starts from the alignment mark position detection device 20 arranged on each sample shot (S01 to S04) as shown in FIG. 5 based on the sample shot information set in advance. Receives the detection position and performs global alignment.

  Next, in step 203, a light control process for detecting the optimum light amount of the measurement light at the time of exposure is performed.

  For each preceding process, the preceding process execution determination unit 150 changes the determination method for the preceding process re-execution from information obtained during processing such as measurement performed before the preceding process. In the second embodiment, the information obtained during the dimming process of the measurement light in step 203 is the preceding process 2 performed in the subsequent step 204 (surface position information offset management: Japanese Patent Application No. 9-045608). Used to determine whether to re-execute.

  In this embodiment, at this time, from the reflectance distribution in the sample shot to be measured, a high reflectance position (abnormal measurement value position) in the sample shot is obtained by means such as threshold processing and is controlled from the surface position detection device 14. The data is received by the timing management unit 170 provided in the apparatus 13 and recorded in the database. At this time, when the obtained high reflectance position moves by a certain amount, or when the amount of reflected light exceeds a preset threshold value (threshold value c), the remeasurement execution flag of the surface position measurement preceding process 2 Stand up.

  Further, when the amount of reflected light at the high reflectance position exceeds a preset threshold value (threshold value d), the correction amount recorded in the database without performing re-execution of the preceding process 2 is changed to the high reflectance. Rewriting is performed according to the displacement or change amount of the position (steps 351 and 352 in FIG. 8).

  In the above description, the value of the database is rewritten, but when the threshold value d is exceeded, a determination flag for re-execution of the preceding process is set, and the object plane at the time of the next preceding process 2 measurement according to the amount of change acquired at this time The dimming value may be predicted, and the time required for the measurement of the preceding process 2 may be shortened, or the validity of the result of the preceding process 2 may be determined.

  Next, focus offset measurement (preceding process 2) for offset management of surface position information proposed in Japanese Patent Application No. 9-045608 is performed by the timing management unit 170 provided in the control device 13. It is determined whether or not to perform (step 204).

  The timing management unit 170 analyzes the data currently recorded in step 251.

  Here, it is determined by the flowchart of FIG. In FIG. 7, a determination is made based on the conditions indicated in steps 301 to 305, and if all the conditions are satisfied, a determination is made in step 306 that the preceding process is not executed.

  If at least one of the conditions indicated in steps 301 to 305 is not satisfied, a determination is made in step 307 to re-execute the preceding process.

  If execution of the preceding process 2 is determined, remeasurement is performed in step 252 and the result is recorded in the database in step 253.

  When the correction value necessary for detecting the position of the surface during exposure is obtained by the preceding process, the control device 13 calculates the position of the exposure area accurately using the laser interferometer 16 and uses the stage driving device 12. After the stage 3 is positioned, the exposure process is started (step 205).

  In the exposure process of step 205, the light amount incident on each measurement point on the exposure area is adjusted using the surface position detection device 14 while referring to the data measured in step 202. Then, from the surface position information measured by the surface position detection device 14 and the focus offset measured in the preceding process 2, the positional deviation amount between the exposure area and the imaging surface of the projection lens system 1 is calculated, and the stage driving device 12 is operated. The exposure is performed while the stage 3 is being driven.

  After the above processing is performed on all the wafers in the lot, the exposure lot is exchanged in step 106, and when all the lots are completed, the exposure is terminated.

  In the second embodiment, the reflectance distribution in the shot that can be acquired during the dimming process in step 203 is used for the determination of the re-measurement of the preceding process and the correction of the correction value registered in the database. The same processing may be performed from information that can be acquired during other processing, such as the amount of reflected light during the exposure processing.

  Further, the value of each setting parameter in the determination shown in FIG. 7 may be updated from the frequency of correction or the correction amount. For example, when the correction frequency is large and the correction amount is large, it is more effective to set at least one of the set time, the allowable error count, the set number of sheets, and the set threshold for determining whether to perform the preceding process again more strictly. Precise processing can be performed at appropriate timing.

  In the present invention, in the first and second embodiments, the preceding process 1 and the preceding process 2 are managed separately, but the same applies to other preceding processes including at least one or both of the preceding processes. Measurement timing can be managed by this method.

The flowchart which shows the exposure sequence by the 1st Embodiment of this invention. Flow chart for managing the execution timing of preceding processes according to the embodiment of the present invention The flowchart which shows the exposure sequence by the 2nd Embodiment of this invention. Schematic showing the main part of a projection exposure apparatus according to an embodiment of the present invention Explanatory drawing which shows the sample shot arrangement | positioning of the to-be-exposed area | region on a wafer, and a measurement offset in the projection exposure apparatus by embodiment of this invention Explanatory drawing which shows the relationship between the measurement point on a wafer, and exposure area in the projection exposure apparatus by embodiment of this invention The figure which shows the flow of a timing determination process according to embodiment of this invention. The flowchart which shows the correction process of the correction value at the time of the surface position detection performed at the time of prior process non-execution according to 2nd embodiment of this invention The figure which shows transition of the reflected light amount difference recorded on the database in the point P between sample shot S01-> S02 shown in FIG. 5 according to embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projection lens system 2 Wafer 3 Wafer stage 4 High brightness light source 5 for wafer surface position detection Illumination lens 6 Mask with pinhole 7 Imaging lens 8, 9 Bending mirror 10 Detection lens 11 Position detection for wafer surface position detection Element 12 Stage drive device 13 Control device 14 Surface position detection device 15 Laser reflection mirror 16 Laser interferometer 17 Half mirror 18 High-intensity light source 19 for alignment mark detection Position detection device 20 for alignment mark detection Alignment mark position detection device 21 Reticle Pattern projection area 24 Alignment mark 30 Exposed areas 61-65 Detection light beam for wafer surface position detection

Claims (6)

  In an exposure apparatus provided with an exposure method for focusing an object plane in the vicinity of an imaging plane of a projection optical system on a focal plane of the projection optical system using a position detection unit that detects a surface position on the object plane. It is obtained by the execution timing of a plurality of preceding processes executed in advance prior to exposure and the preceding processes before exposure in order to obtain a set value necessary for detecting the optimum focus plane of the object plane set in advance at the time of exposure. An exposure apparatus comprising a mechanism for storing and managing a correction amount for detecting an optimum focus plane of the object plane.   2. The exposure apparatus according to claim 1, wherein a plurality of preceding processes are executed in advance prior to exposure to obtain a set value necessary for detecting an optimum focus plane of the object plane set in advance at the time of exposure. The exposure elapsed time, the total number of exposures of the object to be exposed, the total number of exposures, the error occurrence rate during exposure, etc., during any preceding processing sequence that was performed immediately before or before, or during the exposure process An exposure apparatus for determining by combining at least one condition of a value given by a change in reflectance of an object to be exposed calculated during processing.   3. The exposure apparatus according to claim 2, wherein the exposure elapsed time, the total number of exposures of the object to be exposed, the total number of exposures, the error occurrence rate during exposure, or the change in reflectance of the object to be exposed calculated during execution of other processing. An exposure apparatus characterized in that a parameter for determining the execution timing of the preceding process can be arbitrarily set from the conditions given in (1).   4. The exposure apparatus according to claim 3, wherein the parameter value for determining the next preceding process execution timing is determined from the amount of change of various measurement values according to claim 2 that can be acquired during the previous measurement value or other process execution. An exposure apparatus characterized in that it can be corrected.   3. The exposure process execution timing management mechanism according to claim 2, wherein the preceding process execution timing management mechanism is obtained by using the previous measurement value or various measurement values according to claim 2 that can be acquired during execution of another process even when the preceding process is not performed. An exposure apparatus for correcting a correction amount for detecting the surface position of the object plane stored in the apparatus.   The exposure apparatus according to claim 2, for detecting the surface position of the object surface at the time of next measurement from the previous measurement value or the amount of change of various measurement values according to claim 2 that can be acquired during other processing. An exposure apparatus that predicts a change in the correction amount.