JP2006234769A - Position measuring method and position measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position measuring method capable of efficiently measuring position and improving a through-put by using measuring marks applied in turn to a plurality of substrates. <P>SOLUTION: In the position measuring method containing measuring marks in an effective measuring range in the view field of an imaging optical system by horizontally moving a stage, a plurality of substrates where the measuring marks are formed on the same position on each are placed in turn. A stage drive mechanism is driven so that the stage positions in a pre-stored specific position (S2), the distance from the measuring mark to the effective measuring range is calculated after moving the stage. This distance is stored and a new predetermined position is derived by adding the distance to the predetermined position (S5). When the measuring mark comes off the effective measuring range, the stage is moved for the calculated distance and after containing the measuring mark in the effective measuring range, the predetermined measurement is performed. The stage drive mechanism is moved so as to position the stage putting the next substrate to the derived new predetermined position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention has an imaging optical system that images a measurement mark formed on a substrate placed on a horizontally movable stage, and performs a predetermined position measurement by horizontally moving the stage and measurement. The present invention relates to a position measuring apparatus that measures the position of a substrate using an image signal of a mark.

  In a photolithography process for forming a semiconductor pattern on a wafer, a plurality of patterns are stacked on the wafer on the stage using a plurality of photomasks (reticles) on which patterns corresponding to the respective processes are formed. In order to form a semiconductor pattern by laminating a plurality of patterns, the lower layer pattern formed on the wafer placed on the stage and the upper layer pattern laminated thereon by exposure using a photomask are correct. It is necessary to have a positional relationship, and for example, measurement and detection of a pattern overlay position shift is performed. In overlay position measurement detection, a registration mark is formed on the ground mark formed on the substrate during the formation of the resist pattern to form a measurement mark (overlay mark), and the overlay position deviation of the resist mark with respect to the ground mark This is done by measuring the quantity.

  For this reason, the exposure apparatus used in the photolithography process includes a stage moving device that horizontally moves the stage, and a position measuring device that optically measures and detects measurement marks formed on the wafer on the stage. The stage moving device is provided with a drive mechanism such as a motor for horizontally moving the stage, and a laser interferometer that constantly detects the two-dimensional coordinates of a reference point set at an appropriate position on the stage. The stage is moved by outputting a control signal for controlling the position of the stage to the drive mechanism. The position measuring device is disposed opposite to such a stage, has an illumination optical system that irradiates the measurement mark with illumination light, and an imaging optical system that forms an image of the measurement mark from the reflected light, The imaging optical system captures an image with a CCD camera or the like, and the captured image is subjected to image processing to measure the registration mark overlay amount with respect to the base mark.

  The formation position of the measurement mark is determined at the wafer design stage. Therefore, when moving the stage so that the measurement mark formed on the wafer placed on the stage is positioned within the effective measurement range of the imaging optical system of the position measuring device (for example, the center of the detection visual field) The position information of the measurement mark formed above is stored in advance in the control unit of the stage moving device, and this is corrected with the correction value of the alignment (positioning) error to calculate the target coordinates, and the reference point set on the stage The stage is horizontally moved by outputting a control signal to the drive mechanism so that the coordinates of the target take the target coordinates (for example, Patent Document 1).

Further, in the manufacture of semiconductor devices and the like, a plurality of wafers are usually set as a unit (also referred to as “lot”), and the same processing is sequentially performed on each wafer in this unit. In a plurality of wafers constituting such a set of processing units, the overlay position deviation detection using the measurement mark is performed one by one on the stage, but the measurement mark is formed at the same position. Yes. For this reason, the target coordinates stored in order to position the measurement mark within the effective range of the position measurement apparatus can be shared among a plurality of wafers constituting a lot.
Japanese Patent Laid-Open No. 11-251377

  By the way, in the manufacturing process of a semiconductor device, there exists a problem that distortion arises in the whole wafer, for example by processing being performed at high temperature and short time in an etching process. If there is such a distortion, an error occurs between the position information of the measurement mark determined at the design stage and the actual position of the measurement mark, and even if the stage reference point is moved to the target coordinates, the measurement mark May not be located within the effective measurement range of the position measurement device, and the stage must be moved again to be within the effective measurement range.

  For a plurality of wafers constituting a lot, the same processing is sequentially performed on the plurality of wafers by the same apparatus. Therefore, if distortion occurs in the semiconductor device manufacturing process, Similar distortion occurs. Furthermore, if the position measurement is performed by sharing the position information of the measurement mark as described above, if there are wafers that need to be finely adjusted in a plurality of wafers constituting a lot, all other The same fine adjustment needs to be performed on the wafer, and there is a problem that the throughput as the exposure apparatus is significantly reduced.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a position measurement method that can efficiently perform position detection using measurement marks sequentially performed on a plurality of substrates and improve throughput. To do.

  In order to achieve the above object, a position measuring method according to the present invention includes a stage on which a substrate on which a measurement mark is formed can be placed and can be moved horizontally by driving a stage driving mechanism, and the stage is placed on the stage. An imaging optical system that images the measurement mark provided opposite to the substrate, and moves the stage horizontally to place the measurement mark within the effective measurement range in the detection field of the imaging optical system. In the position measurement method for performing measurement, a plurality of substrates each having a measurement mark formed at the same position are sequentially placed on the stage to perform predetermined measurement, and it is assumed that the measurement mark is within the effective measurement range. Drive the stage drive mechanism so that the stage is located at the memorized predetermined position, calculate the distance from the measurement mark to the effective measurement range after moving the stage, and this distance The new predetermined position is derived by storing and adding this distance to the predetermined position, and when the measurement mark is out of the effective measurement range, the stage is moved by the calculated distance to bring the measurement mark within the effective measurement range. The stage driving mechanism is driven so that the stage on which the next substrate is placed is positioned and the stage on which the next substrate is placed is positioned at the new predetermined position derived as described above.

  In addition, when a plurality of measurement marks are provided on a plurality of substrates with the same formation position, the predetermined positions are stored corresponding to each of the plurality of measurement marks. On the other hand, it is preferable to derive the new predetermined position.

  The semiconductor substrate position measuring apparatus according to the present invention is a stage on which a semiconductor substrate on which a measurement mark is formed is placed, a horizontally movable stage, and an imaging means for imaging the measurement mark and outputting an image signal of the measurement mark. And a measurement control means for capturing the measurement mark in the measurement effective range of the detection visual field of the imaging means by driving the stage and measuring the position of the semiconductor substrate using the image signal of the measurement mark In the position measuring apparatus, a detecting means for detecting that a measurement mark of another semiconductor substrate is out of a measurement effective range of the imaging means when another semiconductor substrate is placed on the stage, and a detection signal from the detecting means And a drive control means for calculating a positional deviation amount between the measurement mark and the effective measurement range and controlling the stage by the positional deviation amount when the next semiconductor substrate is placed on the stage. Eteiru.

  According to the position measurement method according to the present invention, a plurality of substrates on which measurement marks are formed at the same position are sequentially replaced to perform a predetermined measurement, and the predetermined measurement stored as being within the measurement effective range. The stage drive mechanism is driven so that the stage is positioned at the position, and the distance from the measurement mark to the effective measurement range is calculated and stored, and this distance is added to the pre-stored predetermined position to obtain a new predetermined position. Derived. Then, the stage driving mechanism is driven so that the stage is positioned at a new predetermined position derived from the next substrate position measurement. For this reason, even if the measurement mark needs to be adjusted out of the effective measurement range at the previous position measurement, the measurement mark is kept within the effective measurement range without performing such re-movement at the next substrate position measurement. The throughput of the apparatus using this position measuring method can be improved.

  According to the position measuring apparatus according to the present invention, in the same way as the position measuring method described above, even when the measurement mark needs to be adjusted out of the effective measurement range at the time of the previous position measurement, The measurement mark can be kept within the effective measurement range without re-moving, and the throughput can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an exposure apparatus 80 including a position measuring apparatus 10 and a stage moving apparatus 90 using the position measuring method according to the present invention. First, the outline of the configuration of the exposure apparatus 80 will be described with reference to FIG. The exposure apparatus 80 is used in a photolithography process in semiconductor manufacturing, and optically projects a device pattern precisely drawn on a photomask (reticle) onto a semiconductor wafer or glass substrate coated with a photoresist. And transcribe. Such an exposure apparatus 80 includes an exposure light source 81, an illumination optical system 82, a mask support base 84 that supports a photomask 83, a projection optical system 85, and a stage 86 on which a wafer W is placed. .

  In the exposure apparatus 80, exposure light output from the exposure light source 81 is input to the illumination optical system 82, and is irradiated onto the entire surface of the photomask 83 supported by the mask support base 84 through the illumination optical system 82. The light thus irradiated and passed through the photomask 83 has an image of a device pattern drawn on the photomask 83, and this light is absorbed by the chuck 87 via the projection optical system 85. A predetermined position of the wafer W placed on the stage 86 is irradiated. At this time, the image of the device pattern of the photomask 83 is reduced on the wafer W and imaged and exposed in one shot area SA (see FIG. 3) by the projection optical system 85. This is scanned over the entire wafer, and semiconductor patterns are formed for each of the shot areas SA, SA,.

  The stage 86 includes an XY stage that two-dimensionally positions the wafer W in a plane perpendicular to the optical axis of the projection optical system 85, a Z stage that positions the wafer W in a direction parallel to the optical axis of the projection optical system 85, and the wafer. It consists of a stage that rotates W slightly, a stage that changes the angle with respect to the Z axis and adjusts the inclination of the wafer W with respect to the XY plane, and moves in the XYZ directions and rotates in the XY plane by driving each stage. And the tilt around the Z axis can be adjusted.

  An L-shaped movable mirror 15 is attached to one end of the upper surface of the stage 86, and the laser interferometer 16 is disposed at a position facing the mirror surface of the movable mirror 15. The movable mirror 15 includes a plane mirror having a reflecting surface perpendicular to the Z axis and a plane mirror having a reflecting surface perpendicular to the Y axis. The laser interferometer 16 includes two X-axis laser interferometers that irradiate the moving mirror with a laser beam along the X-axis, and a Y-axis laser interferometer that irradiates the movable mirror with a laser beam along the Y-axis. The X and Y coordinates of the stage 86 are measured by one laser interferometer for the X axis and one laser interferometer for the Y axis, and measurement of two laser interferometers for the X axis The rotation angle in the XY plane is measured by the difference in values.

  As described above, the X coordinate and Y coordinate of the stage 86 are always detected by the laser interferometer 16, and the coordinate system (X, Y) of the stage 86 is determined. That is, the coordinate value of the stage 86 measured by the laser interferometer 16 becomes the coordinate value in the stage coordinate system. A stage position measurement signal indicating the X coordinate and Y coordinate (and rotation angle) measured by the laser interferometer 16 is output to the main controller 6. The main control unit 6 outputs a drive control signal to a stage drive mechanism 7 composed of a motor or the like for driving each of the stages constituting the stage 86 while monitoring the output stage position measurement signal. In addition, an autofocus device (not shown) based on an oblique incidence method for detecting the position of the surface of the wafer W along the Z-axis direction is provided for the wafer W placed on the stage 86, A detection signal indicating the amount of displacement in the Z direction is output to the main control unit 6. The stage 86, the main controller 6, the stage drive mechanism 7 and the laser interferometer 16 constitute a stage moving device 90.

  In the photolithography process, the positional relationship between the lower layer pattern in the region formed on the wafer W and the upper layer pattern stacked by exposure of the photomask 83 needs to be accurate. For this reason, as shown in FIG. 3, rectangular overlay marks SM are provided on the wafer W at a plurality of locations as measurement marks for measuring and detecting pattern misalignment. As shown in FIG. 4, the overlay mark SM formed on the wafer W is formed inside the frame of the rectangular frame-shaped ground mark SMa provided in the lower layer pattern of the wafer before exposure and the ground mark SMa at the time of exposure. The registration mark SMb. Such an overlay mark SM is provided on the wafer W in an external area of the shot areas SA, SA,... In this embodiment, on the scribe line SL extending in the vertical and horizontal directions between the shot areas SA, SA,. Is provided. By measuring the distance d between the base mark SMa and the registration mark SMb with respect to such an overlay mark SM, it is possible to detect the amount of overlay displacement.

  Furthermore, alignment marks AM (AMX, AMY) used for measurement for accurately positioning the wafer during exposure are formed on the wafer W as measurement marks. As shown in FIGS. 3 and 4, the alignment mark AM is formed by a line and space pattern in which the ends of the plurality of line portions L, L,... Are aligned at equal intervals. Similarly to the above, it is provided on the scribe line SL. On the scribe line SLX extending in the X direction, as shown in FIG. 4B, the alignment mark AMX with the alignment direction of the line portions L, L,. As shown in FIG. 4C, an alignment mark AMY is provided with the alignment direction of the line portions L, L,.

  The exposure apparatus 80 of this embodiment is provided with a position measuring apparatus 10 that optically detects the position of the overlay mark SM. The position measuring apparatus 10 includes a stage 86 on which the wafer W is placed, a light source 1 that irradiates illumination light onto the overlay mark SM formed on the wafer W placed on the stage 86, An illumination optical system 2 that guides the illumination light to the wafer W and irradiates the wafer W perpendicularly, and an image that forms reflected images (including diffracted light) from the illumination optical system 2 on the imaging surfaces 41 and 46. The optical system 3, CCDs 40 and 45 as photoelectric conversion elements that convert the reflected light received by the imaging surfaces 41 and 46 into electrical signals and output them, and the signals from the CCDs 40 and 45 are processed and overlapped The signal processing unit 5 detects the position of the alignment mark SM. Such a position measuring apparatus 10 is configured as an FIA (Field Image Alignment) type position measuring apparatus, and is an off-axis type that directly measures the mark position on the wafer W without using the projection optical system 85 of the exposure apparatus 80. It is configured.

  The light source 1 includes, for example, a halogen lamp, and emits light including a wide wavelength range of 530 to 800 nm that does not sensitize a photosensitizer such as a resist for photolithography process applied on the wafer W.

  Irradiation light from the light source 1 is converted into a parallel light beam by the collector lens 21. Irradiated light converted into a parallel light beam by the collector lens 21 is a filter group including a wavelength selection filter 22a including an infrared absorption filter, a short wavelength cut filter, a long wavelength cut filter, and the like, and a neutral density filter 22b capable of moving back and forth with respect to the optical path. The wavelength range and intensity required for the measurement light are selected. In addition, the incident end 24a of the light guide 24 is positioned at the imaging position of the condenser lens 23, and the illumination light that passes through the filter group 22 and is collected by the condenser lens 23 enters the light guide 24 from the incident end 24a. Is incident on. The light beam incident on the light guide 24 propagates through the light guide 24 and exits from the exit end 24b. As described above, the light source 3 is integrated with the light source 1 from the light source 3 to the incident end 24 a of the light guide 24.

  An exit end 24b of the light guide 24 is provided in the sensor unit 12. Irradiation light emitted from the exit end 24b of the light guide 24 is limited via an illumination aperture stop (not shown) and is applied to the condenser lens 25. Incident. The illumination light that has passed through the condenser lens 25 is once condensed in the vicinity of an illumination field stop (not shown), and the illumination light that has become a parallel light flux through the illumination relay lens 26 via the illumination field stop is half prism 27. , And enters the objective lens 28. The illumination light collected by the objective lens 28 is reflected downward by the reflecting surface of the reflecting prism 29 and illuminates the overlay mark SM formed on the wafer W by epi-illumination. As described above, the illumination optical system 2 is configured by the collector lens 21 to the reflecting prism 29.

  The reflected light from the overlay mark SM obtained by the irradiation light from the light source 1 enters the half prism 27 via the reflecting prism 29 and the objective lens 28. Reflected light in the half prism 27 is reflected upward in the drawing, is further reflected by the reflecting mirror 34 via the second objective lens 31 and the relay lens 33, and enters the XY branch half prism 36 via the relay lens 35. The light transmitted through the XY branch half prism 36 enters the imaging surface 41 of the X direction CCD 40, and the light reflected from the XY branch half prism 36 enters the imaging surface 46 of the Y direction CCD 45. Thus, the position of the overlay mark SM and the positions of the imaging surfaces 41 and 46 are set in a conjugate positional relationship. Image formation that forms an image of the reflected light from the overlay mark SM by the reflection prism 29, the objective lens 28, the half prism 27, the second objective lens 31, the relay lenses 33 and 35, and the XY branch half prism 36 described above. An optical system 3 is configured, and the imaging optical system 3 forms a detection visual field 3a schematically shown in FIGS. 5 and 6, and an overlay mark SM is set within a predetermined range centering on the detection visual field center C in the detection visual field 3a. The measurement effective range ER that can effectively perform the position shift detection using is formed.

  The CCDs 40 and 45 that receive the reflected light from the overlay mark SM on the imaging surfaces 41 and 46 by the imaging optical system 3 photoelectrically convert the image of the overlay mark SM imaged on the imaging surfaces 41 and 46. An image signal is generated, and this image signal is output to the signal processing unit 5. The signal processing unit 5 performs image processing on the image signals output from the CCDs 40 and 45, and calculates the position information of the overlay mark SM by, for example, obtaining the center of the image of the overlay mark SM. The mark position information calculated in the signal processing unit 5 is output to the main control unit 6.

  Normally, in a semiconductor device manufacturing process, a plurality of predetermined wafers W subjected to the same processing are handled as a set of processing units (hereinafter also simply referred to as “lots”), and the processing of the wafers W is sequentially performed. For example, in a photolithography process performed using an exposure apparatus, a plurality of wafers W constituting a lot are placed on the stage 86 one by one on the stage 86, and all shot areas SA of the placed wafers W are placed. After the transfer by exposure, the overlay position SM is measured using the overlay mark SM, the next wafer W is transferred to the stage 86, and the same process as the previously placed wafer W is performed. Yes. Hereinafter, the measurement and detection of misalignment using the overlay mark SM by the position measurement method according to the present invention for a plurality of wafers W constituting such a lot will be described with reference to the flowchart of FIG.

  First, the first wafer W among the wafers W constituting the lot is placed on the stage 86 (step S1). The wafer W is accurately placed on the stage 86 by mechanical alignment using the orientation flat OF. At this time, the coordinates of the reference point F set on the stage 86 are (0, 0). Then, among the plurality of overlay marks SM, SM,... Formed on the first wafer W, the overlay mark SM1 to be measured is within the measurement effective range ER of the imaging optical system 3. The stage is moved (step S2). In this stage movement, position information of each overlay mark SM, SM,... Is stored in the main control unit 6 in advance, and the reference point F of the stage 86 is overlapped with the measurement target from the current position (0, 0). By moving to the target coordinates (X1, Y1) obtained based on the position information of the mark SM1, the overlay mark SM1 to be measured is within the effective measurement range ER of the position measuring device 10. That is, the main control unit 6 outputs a drive control signal for the stage drive mechanism 7 while monitoring the stage position measurement signal output from the laser interferometer 16, and moves the stage 86 by X1 in the X direction and Y1 in the Y direction. (See FIG. 5).

  After the movement of the stage 86, the center position of the overlay mark SM1 in the detection visual field 3a of the imaging optical system 3 is measured (step S3), and the main control unit 6 is based on the image signal output from the signal processing unit 5. Thus, the distance between the mark center and the detection visual field center C that is the center of the effective measurement range ER is calculated (step S4), and this distance is stored in the main controller 6 (step S5). Here, the target coordinates (X1, Y1) are obtained based on the design coordinates so that the overlay mark SM1 falls within the measurement effective range ER. However, the target coordinates (X1, Y1) are obtained through a semiconductor device manufacturing process such as an etching process. The entire wafer W is distorted, and an error occurs between the position information of the overlay mark SM1 stored in advance and the actual position. Therefore, there may be a distance between the mark center and the detection visual field center C as shown in FIG. Note that the distances ΔX1, ΔY1 in the respective directions are obtained as the distance between the mark center and the detection visual field center C stored in step S5 by dividing the X-direction light component and the Y-direction light component.

  Next, based on the distance between the mark center calculated in step S4 and the detection visual field center C, it is determined whether the overlay mark SM1 is within the measurement effective range ER or not (step S6). When it is determined by the determination that the overlay mark SM1 is within the effective measurement range ER, the positional deviation is detected using the overlay mark SM1 (step S8).

  If the mark center and the detection visual field center C are in the positional relationship as shown in FIG. 6 and it is determined in step S6 that the overlay mark SM1 is outside the measurement effective range ER, the stage 86 is moved to step S4. Is moved in the X direction by a distance ΔX1 in the X direction calculated in step S1, and is moved in the Y direction by a distance ΔY1 in the Y direction (step S7). That is, the drive control signal is output to the stage drive mechanism 7 while the output signal from the laser interferometer 16 is monitored by the main control unit 6 so that the coordinates of the reference point F of the stage 86 are (X1 + ΔX1, Y1 + ΔY1). . By this movement of the stage 86, the overlay mark SM1 that was outside the measurement effective range ER after the first stage movement can be accommodated in the measurement effective range ER. When the overlay mark SM1 is within the measurement effective range ER, the misalignment is detected using the overlay mark SM1 (step S8).

  Then, on the wafer W placed on the stage 86, it is determined whether or not all the overlay marks SM1, SM2,. If it is determined, the process returns to step S2 to detect misalignment using the next overlay mark SM2. As for the overlay mark SM2, as described above, target coordinates (X2, Y2) for storing the overlay mark SM2 within the effective measurement range ER are stored in advance, and the reference point F takes this target coordinate. In this manner, the stage driving mechanism 7 is driven to move the stage 86. Further, the distance between the center of the overlay mark SM2 and the measurement visual field center C is calculated after moving the stage, and this distance is stored in the main controller 6. As described above, the main controller 6 stores the position information of each of the overlay marks SM1, SM2,..., And the distance between the mark center and the detection visual field center C after the stage movement based on the position information. It is stored in correspondence with each overlay mark SM1, SM2,.

  If it is determined in step S9 that all the processes for the wafer W placed on the stage 86 have been completed, the second wafer W constituting the lot is placed on the stage 86 instead of the first wafer W. (Step S1), the same processing is performed on the second wafer W (Steps S2 to S9).

  As described above, each of the wafers W constituting the lot is provided with a measurement mark at the same location. Like the first wafer W, the overlay mark SM1 is placed within the measurement effective range ER of the imaging optical system 3. The stage 86 is moved so as to be within the range (step S2). At this time, in order to keep the overlay mark SM1 within the measurement effective range ER, a step is performed in the position measurement of the first wafer at the target coordinates (X1, Y1) stored in advance as the target coordinates of the reference point F of the stage 86. New target coordinates (X1 + ΔX1, Y1 + ΔY1) obtained by adding the distance between the detection visual field center and the mark center calculated in S4 are used. That is, the main control unit 6 outputs the drive control signal of the stage drive mechanism 7 while monitoring the stage position measurement signal output from the laser interferometer 16, and the coordinates of the reference point F of the stage 86 are (X1 + ΔX1, Y1 + ΔY1). Thus, the stage 86 is moved by X1 + ΔX1 in the X direction and by Y1 + ΔY1 in the Y direction.

  Next, as in the case of the first wafer W, the center position of the overlay mark SM1 is measured (step S3), the distance between the mark center and the detection visual field center C is calculated (step S4), and this distance is mainly used. The information is stored in the control unit 6 (step S5). Further, based on the distance calculated in step S4, it is determined whether the overlay mark SM1 is within the measurement effective range ER or not (step S6). If it is determined by this determination that the overlay mark SM1 is within the effective measurement range ER, the misalignment detection using the overlay mark SM1 is performed (step S8). When it is determined that the overlay mark SM1 is outside the effective measurement range ER, the drive control of the stage drive mechanism 7 is performed by the main control unit 6 based on the distance calculated in step S5, and the stage 86 is moved. (Step S7). After the stage is re-moved in step S7, it is assumed that the overlay mark SM1 is within the effective measurement range ER, and the positional deviation detection using the overlay mark SM1 is performed (step S8). Note that the overlay mark SM may not be within the measurement effective range ER even if the stage 86 is moved to the target coordinates obtained based on the position information stored in advance for the first wafer W. As described above, this is caused by the overall distortion of the wafer W generated in the manufacturing process of the semiconductor device. As in this embodiment, in the wafers W constituting the lot, since the same processing steps are sequentially performed using the same processing apparatus, such a distortion is similarly generated in each wafer. . For this reason, a new target coordinate is calculated by adding an error adjusted so that the overlay mark SM1 formed on the first wafer W falls within the effective measurement range ER, and the reference point F of the stage 86 becomes the reference point F. By moving the stage so as to take new target coordinates, the overlay mark SM1 formed on the second wafer W can be accommodated within the effective measurement range ER.

  When all the positional deviation measurement detection is completed for the second wafer W, the third wafer is placed on the stage 86 from the determination in step S10 (step S1), and thereafter, in the same manner, steps S2 to S9. The process shown in FIG. As described above, as shown in step S10, the wafers are sequentially processed one by one until the processing of all the wafers constituting the lot is completed.

  The target coordinates used in step S2 for the third wafer are the target coordinates stored in advance, the distance between the mark center calculated in the position measurement of the first wafer and the center of the detection visual field, and two It is obtained by adding the distance between the mark center and the detection field center calculated in the position measurement of the eye wafer. As described above, when processing is performed by sequentially replacing the wafers, the target coordinates used in step S2 (in the n-th wafer) are changed to the previously stored target coordinates (1 to n). It is assumed that the distance between the center of the detection field and the center of the mark calculated in the position measurement of the (first wafer) is added.

  As described above, according to the position measuring method according to the present invention, a plurality of wafers in which measurement marks are formed at the same position and the same processing steps are sequentially performed like wafers constituting a lot. When the stage is moved to the target coordinates based on the information stored in advance, the distance from the center of the measurement mark to the center of the detection visual field is stored, and this distance is added to the target coordinates based on the information stored in advance. The target coordinates are derived, and when the stage on which the next wafer is placed is moved, the target coordinates are moved to the new target coordinates derived by the previous wafer position measurement. Therefore, even if the measurement mark needs to be adjusted outside the effective measurement range at the previous position measurement, the possibility of the measurement mark falling outside the effective measurement range at the next wafer position measurement can be reduced. , No need to move again. Thereby, the time required for position measurement can be largely omitted, and the throughput of the exposure apparatus can be improved. Similarly, according to the position measuring apparatus of the present invention, the time required for position measurement can be largely omitted, and the throughput can be improved.

  Further, in the present embodiment, even in the second and subsequent sheets, in the process of step S5, the target coordinates are updated by adding further errors to the target coordinates already including the errors. For this reason, the error can be averaged as the number of sheets is increased, and the possibility that the measurement mark is out of the effective measurement range can be reduced as the number of processed sheets increases.

In the above-described embodiment, the position measuring apparatus is configured as the FIA system. However, the position measuring apparatus is not necessarily limited to this, but is not limited to this.
Even if it is configured as an (Interferometric Alignment) method, it can be implemented in the same manner, and the same effect can be obtained.

  Further, in the description with reference to FIG. 7 of the present embodiment, the overlay mark SM has been described as an example of the measurement mark used for position measurement. However, the mark is not necessarily limited to such a form. , 4 (b), (c), the position measurement using the alignment mark AM formed with the line and space pattern can be similarly performed, and the same effect can be obtained.

It is a block diagram which shows the structure of the exposure apparatus using the position measuring method which concerns on this invention. It is a block diagram which shows the structure of the position measuring apparatus with which the said exposure apparatus is equipped. It is a top view which shows a wafer. It is a top view which shows a measurement mark, (a) is an overlay mark, (b) is an X direction mark, (c) is a top view which respectively shows a Y direction mark. It is a figure which shows a stage movement typically. It is a figure shown about a detection visual field and a measurement effective range. It is a flowchart shown about the position measuring method which concerns on this invention.

Explanation of symbols

W wafer (substrate)
SM Overlay mark (measurement mark)
AM alignment mark (measurement mark)
DESCRIPTION OF SYMBOLS 1 Light source 2 Illumination optical system 3 Imaging optical system 5 Signal processing part (measurement control means)
6 Main control unit 7 Stage drive mechanism 10 Position measuring device 16 Laser interferometer 40, 45 CCD (light source conversion element)
80 Exposure device 86 Stages S4 and S5 (detection means)
S6, S7 (drive control means)

Claims (3)

A stage on which a substrate on which a measurement mark is formed can be placed and can be moved horizontally by driving a stage drive mechanism, and the measurement mark is provided to face the substrate placed on the stage. In a position measuring method for measuring a predetermined position by horizontally moving the stage and placing the measurement mark within a measurement effective range in a detection visual field of the imaging optical system,
A plurality of the substrates each having the measurement mark formed at the same position are sequentially mounted on the stage to perform the predetermined position measurement,
Driving the stage driving mechanism so that the stage is positioned at a predetermined position stored in advance as the measurement mark falls within the measurement effective range;
Calculate an adjustment distance from the measurement mark to the effective measurement range after moving the stage, store the distance and add the distance to the predetermined position to derive a new predetermined position;
When the measurement mark is out of the effective measurement range, the stage is moved by the distance, and the measurement mark is placed in the effective measurement range to perform a predetermined measurement,
A position measuring method, wherein the stage driving mechanism is driven so that the stage on which a next substrate is placed is positioned at the new predetermined position.   The plurality of substrates are provided with a plurality of measurement marks having the same formation position, and the predetermined positions corresponding to the plurality of measurement marks are stored, respectively. 2. The position measuring method according to claim 1, wherein the new predetermined position is derived. A stage on which a semiconductor substrate on which a measurement mark is formed is placed and can be moved horizontally;
Imaging means for imaging the measurement mark and outputting an image signal of the measurement mark;
A measurement control unit that drives the stage to capture the image of the measurement mark within a measurement effective range of the detection visual field of the imaging unit, and measures the position of the semiconductor substrate using an image signal of the measurement mark. In the position measurement device of the substrate
Detecting means for detecting that the measurement mark of the other semiconductor substrate is out of the measurement effective range of the imaging means when another semiconductor substrate is placed on the stage;
Drive control for calculating a displacement amount between the measurement mark and the effective measurement range from the detection signal from the detection means, and driving the stage by the displacement amount when the next semiconductor substrate is placed on the stage. And a position measuring device.

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