JP5346759B2 - Substrate positioning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily achieve precise positioning by obtaining a relative position of a substrate after being mounted on a stage. <P>SOLUTION: A substrate positioning apparatus is composed of the stage 5, a stage moving mechanism 51, and a camera 6, which images a surface of the substrate W. The position of the center of rotation of the substrate W is corrected through centering processing using substrate rotation center position information generated by imaging an alignment mark 204 with a low magnification. In a step S18, the position of the substrate W is measured from substrate end information using the alignment mark 205 image with the low magnification and a scribe line region 203, and in a step S20, the angle of rotation of the substrate W is corrected based upon the measurement result. In a step S21, the tilt angle is corrected. In a step S22, the alignment mark 204 is imaged with a set high magnification, and the position of the center of gravity of the alignment mark 204 is calculated to correct the position of the substrate, thereby positioning the substrate. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a substrate positioning method for correcting the angle and eccentric position of a substrate such as a wafer before being introduced into a semiconductor manufacturing apparatus. In particular, the present invention relates to a positioning method used in a pattern drawing apparatus that draws a pattern on a substrate using the technique.

  Conventionally, in a semiconductor manufacturing apparatus, it is necessary to detect the center, notch, or orientation flat angle of a semiconductor wafer put into the manufacturing apparatus, and a pre-alignment apparatus used for this has been proposed (for example, Patent Documents). 1). In the conventional apparatus, an angle detection means provided on a rotary table on which a wafer is placed and rotated, a length measuring unit disposed near the side surface of the rotating table, and an upper vicinity of the rotating table, and measurement by the length measuring unit The amount of eccentricity of the wafer is calculated from the data, and the notch angle formed on the wafer is calculated from the measurement data of the length measurement unit and the angle detection means.

  On the other hand, the manufacturing process of a semiconductor device can be broadly divided into a process of forming various semiconductor element patterns on a wafer and a process of cutting and separating the wafer into individual chips and sealing them in a package. In recent years, an increase in wafer diameter has been promoted in order to reduce the manufacturing cost, and a reduction in the size and thickness of the package has been desired in order to increase the mounting density.

  Then, before sealing the wafer into individual chips for sealing in a thin package, the surface opposite to the pattern formation surface (main surface) of the wafer (back surface of the wafer) is ground with a grindstone. In addition, the thin film is removed by polishing with loose abrasive grains, etc., and then diced for cutting and separation. However, in this technique, a large number of scratches are made on the back surface of the wafer, and the shape of the outer peripheral edge of the wafer is greatly affected by the thinning. In other words, the wafer is formed to have a circular shape, but a thin curved surface due to the thinning of the peripheral edge portion results in unevenness. In such a thinned wafer, the shape of the notch has to be deformed, and as a result, it is difficult to distinguish it from other irregularities.

  Therefore, in the thinned wafer, there is a problem that the position detection accuracy is poor in the alignment for detecting the notch. Therefore, there is provided a technique for correcting a position of a substrate by detecting a scribe line or an alignment mark formed on the substrate in relation to a method for positioning a wafer. The conventional positioning pattern is a so-called theta mark provided on the scribe line region for relatively rough alignment with the rotation direction of the wafer, and each semiconductor integrated circuit chip repeatedly arranged. It consists of an X direction trimming mark and a Y direction trimming mark for accurate alignment.

  Specifically, this is an alignment method for positioning a wafer provided with an alignment mark, which detects the left and right pre-alignment marks on the substrate at a low magnification, determines the position of the pre-alignment mark, and A first measurement step of acquiring the center, and a second measurement step of measuring a plurality of alignment marks on the wafer at a magnification higher than that and performing precise detection (for example, Patent Document 2).

  Further, in a pattern drawing apparatus or an exposure apparatus that draws a pattern by irradiating a light beam onto a semiconductor substrate or a glass substrate (hereinafter referred to as “substrate”) having a photosensitive material applied to the main surface, the light beam is emitted. As the substrate moves relative to the head portion in the direction along the main surface, a pattern is drawn on the entire substrate. In order to accurately draw a pattern with the pattern drawing apparatus, the relative position between the portion of the substrate irradiated with the light beam and the head portion (that is, the relative position of the substrate with respect to the head portion) needs to be constant. Therefore, a positioning method using an alignment mark on the substrate is considered in the same manner as described above.

JP 2009-88401 A JP 2003-92246 A

  By the way, also in the positioning method using an alignment mark, the request | requirement which performs a detection and measurement in a short time is also high. That is, since it is necessary to increase the number of wafers processed per unit time, it is necessary to shorten the processing time called exposure, which does not involve exposure, as much as possible. However, in the above prior art, a plurality of alignment marks are detected in both the first and second measurement steps, and there is room for improvement in performing measurement in a short time.

  In recent years, an exposure apparatus that uses vacuum ultraviolet rays or soft X-rays as illumination light, which has high resolution on the order of submicrons and can be transferred and printed with high precision, has been developed. Pattern printing with a minimum line width of 0.2 μm is also possible. It became feasible. In such an exposure apparatus that performs printing with high accuracy, it is necessary to align the wafer with the illumination light and the mask with extremely high accuracy. However, the alignment using only the conventional alignment mark provides sufficient accuracy. Can't get.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a substrate positioning method capable of reducing the time required for alignment and obtaining the relative position of the substrate with high accuracy and stability.

In order to solve the above problems, the present invention provides a substrate positioning method for positioning a substrate provided with at least two marks that can be used for positioning measurement, and (A) the substrate among the at least two marks. The horizontal position between the rotation center position of the substrate and the rotation center position of the stage holding the substrate based on the substrate center position information obtained by imaging the mark provided at the rotation center position of the substrate at a low magnification A first position moving step of detecting a shift and moving the stage along a horizontal plane to correct the position of the substrate; and (B) after the first position moving step, of the at least two marks based on the substrate edge position information obtained by imaging the mark provided at an end portion of the substrate, and rotate the stage to correct the position of the substrate around the vertical axis, the surface of the substrate By comparing the location information of the scribe line region of the scribe line region kicked obtained by imaging, and the position information of the pre-registered the scribe line regions in front of the imaging, correcting the position of the substrate a second position moving step of rotating Subeku the stage around the vertical axis, (C) of the at least two marks of the substrate that is moved said first position moving step and the said second position moving step A third position for moving the stage to correct the position of the substrate based on substrate center position information obtained by imaging the mark provided at the rotation center position of the substrate at a magnification higher than the low magnification. And a moving process.

Further, in the substrate positioning method according to claim 1 of the present invention, the substrate center position information in the third position movement step is information on the center of gravity of the mark provided at the rotation center position of the substrate. It is.

Also, in the substrate positioning method according to claim 1 or 2, the imaging in the first position moving step is performed by using the mark provided at the rotation center position of the substrate as a back surface side of the substrate. The imaging is performed by observing at the low magnification through the substrate with infrared rays .

  According to the substrate positioning method of the present invention, the substrate center position is positioned in the first position moving step, and the substrate is positioned based on the substrate end position information and the scribe line information in the second position moving step. Therefore, the substrate position positioned in the first position moving step is corrected, and further, in the third position moving step, the mark is imaged at a high magnification and the substrate position is corrected, so that the substrate is accurately positioned.

According to the substrate positioning method of the present invention, the position of the center of rotation of the substrate is corrected by detecting the position of the center of gravity of the mark imaged at a high magnification. Play.

It is a front view showing one embodiment of a pattern drawing device provided with a substrate positioning device concerning the present invention. It is a top view of the pattern drawing apparatus shown in FIG. It is a block diagram which shows the electrical structure of the pattern drawing apparatus of FIG. It is a figure showing composition of a substrate positioning device concerning one embodiment of the present invention. It is a schematic sectional drawing of the semiconductor device of this embodiment. It is a schematic diagram of the substrate W surface. 4 is a flowchart for explaining the operation of the pattern drawing apparatus 1. It is a flowchart explaining a board | substrate positioning method.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 is a front view showing an embodiment of a pattern drawing apparatus equipped with a substrate positioning device according to the present invention, FIG. 2 is a plan view of the pattern drawing apparatus shown in FIG. 1, and FIG. It is a block diagram which shows the electric constitution of a pattern drawing apparatus. In this pattern drawing apparatus (exposure apparatus) 1, one end side region (the left hand side region in FIGS. 1 and 2) of the base 2 delivers a substrate W such as a semiconductor wafer (hereinafter referred to as “substrate”). In contrast to the substrate delivery region, the other end region (the right-hand region in FIGS. 1 and 2) is a pattern drawing region for pattern drawing on the substrate W. On the base 2, a head support portion 21 is provided at the boundary position between the substrate delivery area and the pattern drawing area. In the head support portion 21, two leg members 211 and 212 are erected upward from the base 2, and a beam member 213 is horizontally provided so as to bridge the top portions of the leg members 211 and 212. Yes. The optical head 3 is mounted on the pattern drawing area side of the head support portion 21 configured in this manner so as to be movable in the vertical direction Z. The head moving mechanism 30 is operated according to an operation command from the exposure control portion 41. By operating, the distance between the substrate W held on the stage 5 described later and the optical head 3 can be adjusted with high accuracy.

  In the substrate delivery area of the base 2, two leg members 221 and 222 are erected on the end opposite to the pattern drawing area. And the box which accommodated the illumination optical system of the optical head 3 is provided so that the top part of the leg members 221 and 222 and the upper surface of the beam member 213 may be bridged. In addition, a camera (imaging unit) 6 that functions as a substrate positioning device is fixed to the side surface of the beam member 213 on the substrate delivery area side, and the surface (drawing surface, exposed surface) of the substrate W held on the stage 5 can be imaged. It has become.

  A substrate storage cassette, a mechanical alignment unit, and a substrate transfer robot (not shown) are arranged in the vicinity of the substrate delivery area. Then, in response to a command from the exposure control unit 41, the substrate W is transported between the substrate storage cassette, the mechanical alignment unit, and the stage located in the substrate delivery area. Further, as described later, the substrate W on which the pattern is drawn in the pattern drawing region is moved to the substrate delivery region together with the stage 5, and is carried into the cassette by the substrate transport robot.

  The stage 5 is moved in the X direction, the Y direction, and the θ direction by the stage moving mechanism 51 on the base 2. That is, the stage moving mechanism 51 has a Y-axis drive unit 51Y (FIG. 3), an X-axis drive unit 51X (FIG. 3), and a θ-axis drive unit 51T (FIG. 3) stacked on the upper surface of the base 2 in this order. The stage 5 is moved and positioned two-dimensionally in a horizontal plane. Further, the stage 5 is rotated around the θ axis (vertical axis) to adjust the relative angle with respect to the optical head 3 to be described later for positioning. As such a stage moving mechanism 51, a conventionally used XY-θ axis moving mechanism can be used.

  Next, the configuration and operation of the optical head 3 will be described. In this embodiment, as described above, the optical head 3 is attached to the head support portion 21 so as to be movable in the vertical direction Z, and emits light to the substrate W moving immediately below the optical head 3. The substrate W held on the stage 5 is exposed by being reflected and a pattern is drawn. In the present embodiment, the optical head 3 can simultaneously irradiate light in a plurality of channels in the X direction, and the X direction corresponds to the “sub-scanning direction”. Further, by moving the stage 5 in the Y direction, a pattern can be drawn two-dimensionally on the substrate W, and the Y direction corresponds to the “main scanning direction”.

  The pattern drawing apparatus 1 configured as described above has a computer 8 as a control unit in order to control the entire apparatus. The computer 8 includes a CPU, a memory 81, and the like, and is disposed in an electrical rack (not shown) together with the exposure control unit 41. Further, the rasterization unit 82, the expansion / contraction rate calculation unit 83, the data correction unit 84, and the data generation unit 85 are realized by the CPU in the computer 8 performing arithmetic processing according to a predetermined program. For example, pattern data corresponding to one LSI is data generated by an external CAD or the like, and is prepared in advance in the memory 81 as LSI data 811. Based on the LSI data 811, the LSI pattern is described later. Is drawn on the substrate W.

  The rasterizing unit 82 divides and writerizes the unit area indicated by the LSI data 811, generates writer data 812, and stores it in the memory 81. Thus, after preparing the raster data 812 or in parallel with the preparation of the writer data 812, the unprocessed substrate W stored in the cassette as described above is unloaded by the robot, and mechanical alignment processing by the pre-alignment unit is performed. After receiving, it is placed on the stage 5 by the robot.

  The stretch rate calculation unit 83 shown in FIG. 3 acquires the alignment mark position on the substrate W and the correction amount of the orientation of the substrate W obtained by the image processing unit 9 described later, and the alignment mark position after alignment. In addition, the expansion / contraction ratio of the substrate W in the main scanning direction Y and the sub-scanning direction X (that is, the expansion ratio of the main surface) is obtained.

  On the other hand, the data correction unit 84 acquires the raster data 812 and corrects the data based on the expansion / contraction rate that is the detection result of expansion / contraction. For this data correction, for example, the method described in Japanese Patent No. 40020248 can be adopted. When the data correction of one divided area is completed, the corrected raster data 812 is sent to the data generation unit 85. . The data generation unit 85 generates drawing data corresponding to the divided area after the change, that is, data corresponding to one stripe.

  The drawing data generated in this way is sent from the data generation unit 85 to the exposure control unit 41, and the exposure control unit 41 controls each unit of the modulation unit 338, the head moving mechanism 30, and the stage moving mechanism 51, thereby making one stripe worth. Is drawn. The exposure operation is performed by the electric field generation control by the modulator 338 as described above. When the exposure recording for one stripe is completed, the same processing is performed for the next divided region, and drawing is repeated for each stripe.

  FIG. 4 is a diagram showing the configuration of the substrate positioning apparatus according to one embodiment of the present invention. The positioning device includes a stage 5, a stage moving mechanism 51, and a camera 6, and the surface of the substrate W is enlarged and imaged by the camera 6. The multi-tone image on the surface of the substrate W is processed by an image processing unit 9 in the computer 8 that performs an alignment process described later. The image processing unit 9 detects an error between the rotation center of the substrate W and the rotation center of the stage 5 by centering processing described in detail later, and drives the stage moving mechanism 51 via the exposure control unit 41. The position of the substrate W is corrected with respect to the optical head 3. That is, it is necessary to determine the positional relationship of the substrate W with respect to the stage 5 on the assumption that the positional relationship of the optical head 3 is maintained with respect to the stage 5, but the substrate W is displaced with respect to the stage 5. If so, the positional relationship of the substrate W with the optical head 3 is maintained by correcting the shift amount by moving the stage 5.

The rotation correction processing Sentari in g of the substrate is corrected, by detecting a rotation error between the X-axis or Y-axis is the reference axis of the alignment mark and the camera 6 of the substrate W, via the exposure control unit 41 the stage By driving the moving mechanism 51, the rotation of the substrate W is corrected. When the rotation error of the substrate is corrected, the image processing unit 9 detects the movement error between the scribe line information of the substrate W and the reference axes X and Y axes of the camera 6, and only the movement error passes through the exposure control unit 41. The stage moving mechanism 51 is moved to complete the tilt angle position correction of the substrate W.

  FIG. 5 is a schematic cross-sectional view of the semiconductor device of this embodiment, and FIG. 6 is a schematic view of the surface of the substrate W. The semiconductor device which is the substrate W of this embodiment has an SOI structure and is formed on a semiconductor substrate (bulk wafer) 101 as shown in FIG. The configuration will be described below.

  An element 103 is formed on the semiconductor substrate 101, and the element 103 is formed on the surface 101 a side of the semiconductor substrate 101. Here, as the semiconductor substrate 101, a silicon wafer or a silicon carbide wafer can be used. Further, as shown in FIG. 6, a scribe line 203 is formed on the surface 101a in element units, CMOS well units, or circuit units to partition these regions. As the element 103, for example, a CMOS, a bipolar transistor, a power transistor, or the like can be formed.

  Next, as shown in FIG. 5, a support substrate 108 for support is bonded to the surface 101 a of the semiconductor substrate 101 on which the element (device) 103 is formed using an adhesive 107. This is to prevent damage to the semiconductor substrate 101 in a process described later. Here, as the support substrate 108 for support, for example, a silicon wafer, a glass substrate, a ceramic substrate, a metal substrate, a tape member, or the like can be used. In this embodiment, a glass substrate is used. The support substrate W is formed to have a larger outer diameter than the semiconductor substrate 101.

  In this state, the support substrate 108 side is supported, and the thickness of the semiconductor substrate 101 is reduced from the back surface 101b side of the semiconductor substrate 101 (hereinafter referred to as thinning). In the thinning method, the thickness is first reduced by grinding and then polished by chemical mechanical polishing. Here, as the abrasive, for example, an organic alkali solution mixed with colloidal silica can be used, and as the abrasive cloth, a polyester nonwoven fabric can be used.

  The stage moving mechanism 51 supports the support substrate 108 of the substrate W during actual pattern drawing. That is, with the back surface 101b of the substrate W facing upward, a light beam is irradiated onto the substrate W from the optical head 3 on a coating film such as a resist applied in advance to the back surface 101b.

  Referring to FIG. 6, the wafer as the substrate W has a plurality of exposure areas 201, and each exposure area 201 is surrounded by a grid-like scribe line area 203. The scribe line region 203 has a strip-shaped portion 203a adjacent to each side of each exposure region 202 having a rectangular outer shape, and a boundary line region 203b between the strip-shaped portion 203a and each exposure region 202. The portion 203a includes one positioning alignment mark 204 at a position corresponding to the center of the substrate W and one positioning alignment mark 205 at a position corresponding to the periphery. Each alignment mark 204, 205 is formed of a multilayer reflective layer having a side of about 0.1 mm. The multilayer reflective layer is formed by a method such as vapor deposition, and efficiently reflects infrared rays.

  The processing operation will be described below with reference to the flowcharts of FIGS. FIG. 8 is a flowchart for explaining the operation of the pattern drawing apparatus 1, and FIG. 8 is a flowchart for explaining a substrate positioning method according to an embodiment of the present invention.

  In the pattern drawing apparatus 1, the substrate W is transported between the substrate storage cassette, the pre-alignment unit, and the stage 5 located in the substrate delivery area in accordance with a command from the exposure control unit 41 (steps S 1, S 2, S 3). .

  Thereafter, the stage 5 is moved to a position immediately below the camera 6 by the stage moving mechanism 51, and the alignment marks (reference marks) on the substrate W are sequentially positioned at the imageable positions of the camera 6, and mark imaging by the camera 6 is executed. Then, pre-alignment (step S4) and fine alignment (step S5) are executed. The image signal output from the camera 6 is processed by the image processing unit 9 in the electrical rack, and the position of the alignment mark on the stage 5 is accurately determined. Here, the alignment may be performed after the stage 5 is moved to a position directly below the optical head 3.

  The pre-alignment process and fine alignment process will be further described with reference to FIG. In the flowchart of FIG. 8, the substrate W is mechanically pre-mechanically aligned (step S <b> 2) by a mechanical alignment process in the pre-alignment unit and mounted on the stage 5 (step S <b> 3), and pre-alignment is performed using the camera 6. Explains the process. First, centering for correcting the deviation between the rotation center of the substrate W and the stage 5 is performed (step S11). By performing the centering process, there is an advantage that the subsequent positioning of the substrate W can be performed only by rotation correction.

  First, the alignment mark 204 at the rotation center position of the substrate W is transmitted through the semiconductor substrate 101 with infrared rays from the rear surface 101b side of the substrate W by the camera 6 and observed at a low magnification (step S12). That is, first, the alignment mark 204 is imaged at a low magnification to obtain the rotation center position of the substrate W, and the result of this processing is used to determine the deviation in the X direction from the rotation center of the stage 5 that is the target position of the alignment mark 204. The deviation in the Y direction is calculated (step S13).

  Here, the low magnification of the magnification by the camera 6 is a magnification at which the alignment mark 204 can be imaged at a size five times larger than the size visually recognized by a person. The imaging area of the substrate W by the camera 6 is a limited area, and it is smaller than the entire substrate W because the apparatus structure is enlarged to make the camera having a field of view range capable of imaging the entire substrate W. A camera whose area is the imaging range is used. Therefore, the magnification by the camera 6 can recognize the presence of the alignment mark 204, and an area having a size including the area where the alignment mark 204 exists when the substrate W is placed with a deviation from the stage 5 is within the imaging range. It is set to enter. Therefore, it is necessary to enlarge the imaging range by the camera 6 in advance as the deviation due to the pre-mechanism alignment process is larger.

  Next, two orthogonal directions (X and Y directions) with respect to the positional relationship of the substrate W with respect to the camera 6 so that the image of the alignment mark 204 on the substrate W is positioned at the center position of the obtained image. The amount of deviation is detected, and this amount of deviation is corrected. At this time, if the substrate W to be aligned is misaligned in the rotation direction, accurate alignment cannot be performed only by the coordinate movement in the orthogonal two-axis direction as described above. It is necessary to correct the rotation of the substrate W (steps S16 and S17). Since the alignment mark 204 detects a deviation from the center position of the obtained image based on information previously arranged at the rotation center position of the substrate W, the image information of the alignment mark 204 is used as the substrate center position information. The determination is made by the image processing unit 9, and the stage moving mechanism 51 is controlled via the exposure control unit 41. Therefore, the operation so far corresponds to the first position movement process of the present invention.

  At this time, if the alignment mark 204 is not detected, an error is displayed on a display unit (not shown) (step S15), and the apparatus 1 is set to the standby mode. Note that the adjustment operation of the stage moving mechanism 51 may be repeated until the alignment mark 204 is detected by a predetermined amount of operation set by the stage moving mechanism 51. For example, a half pitch of the visual field region of the camera 6 may be set, and the search operation may be set to repeat the X-axis movement to the Y-axis movement by half a pitch.

  Here, if the imaging range of the camera 6 is small and the magnification is high, there is a high possibility that the alignment mark 204 will not enter the imaging range. On the other hand, in the case of the substrate W as shown in FIG. 5, deviation occurs at the stage of bonding the semiconductor substrate 101 to the support substrate 108. Further, since the support substrate 108 is formed larger than the semiconductor substrate 101, even when the mechanical alignment process is performed, the displacement of the arrangement of the substrate W is promoted in the stage of placing on the stage 5. In other words, the imaging magnification of the camera 6 in the centering process is preferably set with a lower magnification than the fine alignment process described later, giving priority to the alignment mark 204 entering the imaging range from this viewpoint. .

  The alignment mark 204 is disposed at the rotation center position of the substrate W. However, if the rotation center position information of the substrate W is determined, the alignment mark 204 is not necessarily disposed at the rotation center. That is, if the rotation center position information of the substrate W is searched by image processing based on the shift amount set in advance from the alignment mark 204 arranged in the vicinity of the rotation center, it functions as the alignment mark 204. In this case, the shift amount may be detected in advance from image information on the substrate surface having such an alignment mark.

  Next, the stage 5 is moved to a position where the alignment mark 205 can be imaged by the camera 6, and the alignment mark 205 at the end of the substrate W is detected (step S18). Here, since the distance between the alignment marks 204 and 205 is long, it is affected by the θ component when the substrate W is placed on the stage 5. Therefore, the misalignment angle of the substrate W after centering is corrected by detecting the alignment mark 205. Although the stage 5 is moved when the alignment mark 205 is imaged, the camera 6 may be moved.

  When imaging the alignment mark 205, if the alignment mark 205 is not detected, an error is displayed on the display unit (not shown) as in the detection step (step S14) for the alignment mark 204 (step S15), and the apparatus 1 is set to the standby mode. .

  In step S20, the position of the alignment mark 205 is measured, and the rotation angle position of the substrate W is corrected based on the measurement result. That is, the substrate W after centering the substrate W is rotated so that the alignment mark 205 is positioned at the target position in the biaxial direction. The alignment mark 205 is located at the target position at the end of the substrate W if the substrate W is centered. Therefore, since the deviation from the target position of the obtained image is detected based on the information previously arranged at the end position of the substrate W, the image information of the alignment mark 205 is the image as the substrate end position information. The stage moving mechanism 51 is controlled via the exposure control unit 41 as determined by the processing unit 9.

  Subsequently, in step S21, movement error correction is set. In the substrate positioning operation, the rotation angle correction processing operation of the substrate W is followed by the tilt angle correction processing operation that is a movement error. Note that the magnification of the camera 6 remains at 5 times the low magnification.

  An enlarged multi-gradation image of the scribe line area 203 of the substrate W picked up by the camera 6 is taken into the image processing unit 9. Since the image captured by the image processing unit 9 is an image photographed through the camera 6 as described above, the gradation value is the edge that is the boundary line region 203b of the scribe line region 203 on the substrate W. Change. Therefore, the position information of the scribe line area 203 at the end from the rotation center position of the substrate W is registered in the image processing unit 9 in advance, and this registration information is compared with the information of the scribe line area 203 of the captured image. Subsequent processing is performed.

  An image of the surface of the substrate W is taken, and a linear image of a required portion at an end on the substrate W, for example, the boundary line region 203b of the scribe line region 203, is positioned at a predetermined position (for example, the center position of the image) of the obtained image. Thus, the amount of deviation in the orthogonal biaxial directions (X and Y directions) with respect to the positional relationship of the substrate W with respect to the camera 6 is detected, and this amount of deviation is corrected. At this time, since the substrate W to be aligned is centered, the boundary line region 203b is inclined. Therefore, in order to correct this tilt angle, it is necessary to correct the rotation of the substrate W (step S22). Therefore, the second position movement step of the present invention includes the step of performing the rotation angle correction using the substrate end portion position information by the alignment mark 205 and the step of performing the inclination angle correction by using the scribe line information by the boundary line region 203b. It corresponds to.

  As a method for detecting the boundary area 203b of the scribe line area 203 from the captured image, a so-called binarization process is known. In this method, a multi-tone image obtained by photographing the surface of the substrate W is converted into a binary image by setting, for example, a tone value set by a method called a mode method as a threshold value. 203b is detected.

  In the so-called mode method, when the gradation value histogram of the captured image shows bimodality, a threshold value TH is set in the valley portion between the peaks, and thereby the boundary line region 203b is processed by binarizing the captured image. Detected. When the boundary line area 203b is detected in this manner, the rotation angle between the camera 6 and the substrate W having the boundary line area 203b is obtained by using a pattern recognition method for the binarized captured image. The error is calculated, and the stage 5 on which the substrate W is placed is driven so as to cancel the error. Based on these positional information, the θ-axis drive unit 51T operates to slightly rotate the stage 5 about the vertical axis, and the positional relationship with the optical head 3 is aligned (positioned) as a direction suitable for pattern drawing on the substrate W. Combined).

  If the three sets of mark position information can be calculated in this way, the correction amount of the θ component and the center deviation when the substrate W is placed on the stage 5 and the pre-mechanism alignment process is performed can be determined. Therefore, in the measurement of the position of the alignment mark 204 to be subjected to the next high magnification processing, the target position of the mark is corrected, so it is not necessary to observe at a low magnification. That is, the alignment mark 204 is hardly found even when the imaging range of the camera 6 is imaged at a high magnification. Here, imaging is performed with a high magnification of 20 times, which is a magnification higher than 5 times that is the magnification of the previous process (step S22).

  In step S23, the stage 5 is moved and the camera 6 again sets the rotation center position of the substrate W as the imaging position. Fine alignment processing is performed in which the alignment mark 204 is imaged at a high magnification set at that position, and the center of gravity position of the alignment mark 204 is calculated as center position information of the substrate W to determine the correction movement amount of the alignment mark ( Step S5). Note that the alignment mark 204 shown in FIG. 6 is a mark having a shape that makes detection more difficult during the fine alignment process, and has a square shape as illustrated.

  The square alignment mark 204 is positioned at the rotation center position of the substrate W. However, when the image is captured at a high magnification and the barycentric position is obtained, the barycentric position is positioned at the central position of the obtained image. As described above, the amount of deviation in the orthogonal biaxial directions (X and Y directions) with respect to the positional relationship of the substrate W with respect to the camera 6 is detected, and this amount of deviation is corrected. At this time, the image processing unit 9 is set so that the center position of a pre-registered captured image to be aligned coincides with the gravity center position. In step S23, the step of correcting the position of the substrate W using the substrate center position information based on the gravity center position information of the alignment mark 204 corresponds to the third position movement step of the present invention.

  Here, when the alignment mark 204 is not detected when imaging the alignment mark 204 (step S24), an error is displayed on a display unit (not shown) as in the above-described detection step (step S14) (step S15). 1 is set to the standby mode.

  As described above, in step S18, the position of the boundary line region 203b between the alignment mark 205 and the scribe line region 203 shown in FIG. 6 is measured, and in step S20, the rotation angle of the substrate W is corrected based on the measurement result. to correct. Subsequently, in step S21, tilt angle correction is set. In step S22, the image is picked up at the set high magnification, the position of the center of gravity of the alignment mark 204 is calculated, and the position of the alignment mark is determined. That is, the precise position of the mark is obtained by calculating the center of gravity.

  When this method is used, a plurality of alignment marks are conventionally required for a plurality of alignment measurements. However, this method can be executed with at least two alignment marks. As a result, the processing time in alignment measurement is reduced, and the alignment time can be shortened. Furthermore, the image pickup means of the camera 6 can also be configured without using a camera having a wide viewing angle in the image pickup range. In the pre-alignment process, the mark is imaged at a low magnification, so that the mark is detected quickly, and even if the image is imaged at a high magnification in fine alignment after a large misalignment is corrected, the mark can be found quickly. It is possible to perform alignment with precise position information at a magnification.

  The method for obtaining the alignment mark position is not limited to the binarization process, and there are various methods such as a method for extracting the contour of the mark and performing pattern matching.

  In the fine alignment process, the position of the center of gravity of the alignment mark 204 is detected and position correction is performed so that the position of the center of gravity is positioned at the center of the obtained image. Therefore, a step of extracting information indicating the directions of the X axis and the Y axis from the graphic of the alignment mark 204 and comparing it with graphic information registered in advance may be added. In this way, more precise alignment can be performed.

  Returning to FIG. 7, mechanical alignment by mechanical pre-alignment processing (step S2) is completed, and pre-alignment of the procedure shown in FIG. 8 (step S4) is performed on the substrate W (step S3) placed on the stage 5. Fine alignment is performed (step S5). When the positioning of the substrate W is completed in this way, an exposure process for printing a pattern on the substrate W using the optical head 3 is started based on the positional information in which the displacement amount of the substrate W on the stage 5 is corrected (step S6). ).

  In the pattern drawing apparatus 1, when the optical head 3 reaches the upper end of the substrate W in the main scanning direction, the movement of the substrate W is stopped. Then, after the substrate W is moved by a predetermined distance in the sub-scanning direction, the movement of the substrate W in the main scanning direction is started, and while the substrate W is continuously moved, the height adjustment of the optical head 3 and the light beam ON / OFF control is continuously performed. The above process is repeated while moving the substrate W in the sub-scanning direction, and when the pattern is drawn on the entire substrate W, the pattern drawing process is completed.

  Thus, when drawing on the substrate W is completed and drawing of a desired pattern on the surface of the substrate W is completed, the stage 5 is placed on the substrate delivery position with the drawn substrate W placed thereon (the left region in FIGS. 1 and 2). Then, the substrate transport robot returns the substrate W to the cassette, the next substrate W is taken out, and a series of processes similar to those described above are repeated. Further, when the pattern drawing on all the substrates W stored in the cassette is completed, the cassette is unloaded from the pattern drawing apparatus 1.

  In the above embodiment, marks formed exclusively for the alignment make 204 and 205 are used. However, a shape that is optically detectable on the surface 101a of the substrate W, for example, a structure in the exposure region 201 is used as the alignment mark. Also good. That is, if the shape is optically detectable, the position information can be obtained by registering the shape as an alignment mark in advance.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In addition to the glass substrate for the display device, the pattern drawing apparatus 1 may be a substrate other than a substrate such as a semiconductor substrate or a printed wiring board (of course, it may not be rectangular). Moreover, the function as a position detection apparatus in the pattern drawing apparatus 1 may be used for purposes other than pattern drawing, and can be used for pattern inspection, for example. In this case, the relative position of the substrate with respect to the reference point associated with the position of the camera unit that captures the pattern on the substrate is detected.

DESCRIPTION OF SYMBOLS 1 Pattern drawing apparatus 2 Base 21 Head support part 211,212,221,222 Leg member 213 Beam member 3 Optical head 41 Exposure control part 5 Stage 51 Stage moving mechanism 6 Camera 8 Computer 9 Image processing unit 108 Support substrate 203 Scribe line Region 204, 205 Alignment mark W Substrate

Claims (3)

A substrate positioning method for positioning a substrate provided with at least two marks that can be used for positioning measurement,
(A) The rotation center position of the substrate and the substrate are held based on substrate center position information obtained by imaging the mark provided at the rotation center position of the substrate among the at least two marks at a low magnification. Detecting the horizontal displacement from the rotation center position of the stage
A first position moving step of moving the stage along a horizontal plane to correct the position of the substrate;
(B) After the first position moving step,
The stage is rotated around the vertical axis to correct the position of the substrate based on the substrate edge position information obtained by imaging the mark provided at the edge of the substrate among the at least two marks. ,
By comparing the position information of the scribe line area obtained by imaging the scribe line area provided on the surface of the substrate with the position information of the scribe line area registered in advance before the imaging, A second position moving step of rotating the stage around a vertical axis to correct the position of the substrate;
(C) from the first position moving step and the said low magnification the mark provided on the rotation center position of the substrate of the at least two marks of the substrate that has been moved by the second position moving step and a third position moving step of moving the stage to correct the position of the substrate based on substrate center position information obtained by imaging at high magnification,
A substrate positioning method comprising: 2. The substrate positioning method according to claim 1, wherein the substrate center position information in the third position moving step is gravity center position information of the mark provided at the rotation center position of the substrate. . In the substrate positioning method according to claim 1 or 2 ,
The imaging in the first position movement step is an imaging in which the mark provided at the rotation center position of the substrate is observed through the substrate with infrared rays from the back side of the substrate and observed at the low magnification. A substrate positioning method.

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