JP2011216789A - Position detecting device, superposition device, position detecting method, and method of manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of possibility that an alignment mark formed on the uppermost wafer does not fall within an observing view of a microscope of an alignment device owing to impossibility to directly observe the laminated uppermost wafer and hence to make positional alignment using the lowermost wafer in detecting the positions of the laminated wafers by a transmission optical system in a spare alignment device.SOLUTION: The device includes: a stage; a detecting unit detecting the position of the wafer mounted on the stage; and a controller controlling the detecting unit by switching a plurality of different detection controls for detecting the position of the wafer under a predetermined condition.

Description

  The present invention relates to a position detection apparatus, an overlay apparatus, a position detection method, and a device manufacturing method.

In recent years, an overlay apparatus that manufactures a semiconductor chip having a three-dimensional structure by stacking and bonding a plurality of wafers into individual pieces has attracted attention in recent years. The overlaying device performs positioning with high accuracy by a positioning device when overlaying a plurality of wafers (see, for example, Patent Document 1).
[Prior art documents]
[Patent Literature]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2005-251972

  The alignment apparatus moves the position of the two wafers based on the position of the alignment mark by moving at least one of the wafers while observing the alignment marks formed on the surfaces of the two opposing wafers with a microscope. Match. Here, since the microscope provided in the alignment device is set to a high magnification and the observation field of view is narrow, the wafer is placed so that the alignment mark is within the observation field of the microscope when the wafer is carried into the alignment device. It is desirable to preliminarily adjust the position of.

  Therefore, a preliminary alignment apparatus is used that performs preliminary alignment so that the alignment mark of the wafer enters the observation field of view of the alignment apparatus before the wafer is carried into the alignment apparatus. In this preliminary alignment apparatus, the outer shape of each wafer is often used as a reference for positioning, and a transmissive optical system is used to recognize the outer shape of the wafer with high contrast.

  However, if the wafer to be detected is a laminated wafer that has already been laminated, and the upper wafer has a smaller outer shape than the lower wafer, the transmission optical system can accurately detect the outer shape of the upper wafer. Is difficult. If the upper and lower wafers are stacked without misalignment, there is no problem because the position of the lower wafer matches the position of the upper wafer, but in reality, misalignment occurs at the stage of laminating the wafers. There may be.

  If the positions of the upper and lower wafers do not match, the position of the upper wafer will deviate even if alignment is performed with the position of the lower wafer as a reference. As a result, when the wafer is carried into the aligner, the alignment mark formed on the upper wafer may not be within the observation field of the microscope of the alignment apparatus. As described above, in the conventional preliminary alignment apparatus, depending on the conditions, the alignment mark of the target wafer observed by the alignment apparatus may not be aligned at a position that falls within the observation field of the microscope.

  In order to solve the above-described problem, a position detection device according to a first aspect of the present invention includes a stage, a detection unit that detects the position of the wafer disposed on the stage, and a predetermined condition. A control unit that controls the detection unit by switching a plurality of different detection controls for detecting the position.

  In order to solve the above-described problem, the overlay apparatus according to the second aspect of the present invention includes a stage, a detection unit that detects the position of the wafer placed on the stage, and a predetermined condition. A control unit that controls the detection unit by switching a plurality of different detection controls for detecting the position of the position, and an alignment unit that aligns the wafer based on the position of the wafer detected by the detection unit by control by the control unit, And an overlapping portion that overlaps two wafers aligned by the alignment portion.

  In order to solve the above-described problem, a position detection method according to a third aspect of the present invention is a position detection method for controlling a position detection apparatus including a stage and a detection unit that detects the position of a wafer placed on the stage. Then, the wafer position is detected by a selection step for selecting one detection control from a plurality of different detection controls for detecting the position of the wafer according to a predetermined condition, and the detection control selected in the selection step. Detecting step.

  In order to solve the above problem, a device manufacturing method according to the fourth aspect of the present invention is a device manufacturing method manufactured by stacking a plurality of wafers, and the step of stacking the plurality of wafers includes: In accordance with a predetermined condition, at least one detection control is selected from a plurality of different detection controls for detecting the position of the first wafer, which is one of the plurality of wafers, and the first detection control selects the first At least one detection control is selected from the first detection step for detecting the position of the wafer and a plurality of different detection controls for detecting the position of the second wafer, which is one of the plurality of wafers, according to a predetermined condition. Then, by the selected detection control, the first wafer and the second wafer are respectively mounted on the first detection step for detecting the position of the second wafer and the stage arranged opposite to each other. Then, based on the position of the first wafer detected in the first detection step and the position of the second wafer detected in the second detection step, the overlaying step of aligning and overlaying the first wafer and the second wafer Including.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a top view which shows roughly the whole structure of a superimposition apparatus. It is a top view which shows the structure of a wafer roughly. It is a top view which shows the structure of an upper wafer holder roughly. It is a top view which shows the structure of a lower wafer holder roughly. It is a perspective view which shows the structure of a position detection part roughly. It is a fragmentary sectional view which shows roughly the structure of the position detection part which has imaged the edge of the wafer illuminated by the 1st illumination unit with the 1st imaging unit. It is a conceptual diagram showing the picked-up image image | photographed with the 1st imaging unit. It is a conceptual diagram which shows the example of the three picked-up images image | photographed by three 1st imaging units. It is a fragmentary sectional view which shows schematically the structure of the position detection part which has imaged the edge of the wafer illuminated by the 2nd illumination unit with the 1st imaging unit. It is a conceptual diagram showing the picked-up image image | photographed with the 1st imaging unit. It is a perspective view which shows roughly the structure of the position detection part which image | photographs the edge of the laminated wafer illuminated by the 3rd illumination unit with the 2nd imaging unit. It is a conceptual diagram of the picked-up image containing the edge of the lamination | stacking wafer which the 2nd imaging unit acquired. It is explanatory drawing explaining the method of specifying the position of the notch of a wafer. It is a flowchart which shows the flow of the control of the position detection performed by a position detection part. It is a figure which shows the example in the case of performing position detection by the transmitted light measurement for the laminated wafer. It is a flowchart which shows the flow of the control of the position detection performed by a position detection part. It is a flowchart which shows the flow of the control of the position detection performed by a position detection part.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a plan view schematically showing the overall structure of an overlay apparatus 100 that performs the device manufacturing method according to the present embodiment. In the figure, the plane direction is the XY axis direction, and the gravity direction is the Z axis direction. The overlay apparatus 100 is an apparatus for joining a plurality of wafers on which circuit patterns are formed by superposing and heating and pressing so that electrodes to be joined are in contact with each other.

  The superimposing apparatus 100 includes an atmospheric environment unit 102 and a vacuum environment unit 202 formed in a common casing 101. The atmospheric environment unit 102 has a control unit 110 and an EFEM (Equipment Front End Module) 112 facing the outside of the housing 101. Each element of each device included in the superimposing apparatus 100 is controlled by the control unit 110 that controls and controls the entire superimposing apparatus 100, or the control arithmetic unit provided for each element performs integrated control and cooperative control. Operate. The control unit 110 includes a storage unit 111 that stores information for controlling the overlay apparatus 100.

  The EFEM 112 includes three load ports 113, 114, 115 and a robot arm 116. A FOUP (Front Opening Unified Pod), which is a sealed wafer storage pod, is attached to each load port. A plurality of wafers 120 are accommodated in the FOUP attached to the load ports 113 and 114, and are carried into the atmospheric environment unit 102 by the robot arm 116. The wafer 120 bonded by the atmospheric environment unit 102 and the vacuum environment unit 202 is stored in a FOUP attached to the load port 115.

  The wafer 120 here may be a single-layer wafer in which a plurality of circuit patterns are periodically formed or a single-layer wafer, or a laminated wafer in which a plurality of wafers are laminated. The wafer 120 carried into the atmospheric environment unit 102 by the robot arm 116 is managed by the control unit 110, and it is grasped by the control unit 110 whether the carried-in wafer 120 is a single layer wafer or a laminated wafer. Yes.

  The atmospheric environment unit 102 includes a spare aligner 130, a main aligner 140, a holder rack 150, and a separation mechanism 160, which are arranged inside the housing 101, respectively. The inside of the housing 101 is temperature-managed so that the temperature is substantially the same as the room temperature of the environment in which the overlay apparatus 100 is installed.

  The preliminary aligner 130 is a device for preliminarily aligning the position of the wafer 120 so that the alignment mark of the wafer 120 is within the observation field of the microscope provided in the aligner 140 when the wafer 120 is loaded into the main aligner 140. is there. The spare aligner 130 includes a position detection unit 300 and a mounting unit 360. Then, the wafer 120 accommodated in the FOUP is carried into the position detection unit 300 by the robot arm 116. A notch is provided on the outer periphery of the wafer 120, and the position detection unit 300 detects the position of the wafer 120 by photographing the notch and the edge of the wafer 120. A specific configuration of the position detection unit 300 will be described later.

  The mounting unit 360 includes a holder table 362 and an observer 364. A wafer holder 190 is placed on the holder table 362. Wafer holder 190 is accommodated in holder rack 150 and is transferred to holder table 362 by robot arm 175 and first transfer unit 171 or second transfer unit 172. The observation device 364 is installed on the ceiling frame of the preliminary aligner 130 and observes the wafer holder 190 placed on the holder table 362. A notch is provided on the outer periphery of the wafer holder 190, and the mounting unit 360 adjusts the position of the wafer holder 190 while observing the notch with the observer 364.

  A plurality of insertion holes are provided on the wafer holding surface of the wafer holder 190 and penetrate the front and back of the wafer holder 190. The holder table 362 is provided with a plurality of through holes, and the plurality of lift pins can pass through the through holes and the insertion holes of the wafer holder 190 so that the wafer 120 can be placed on the lift pins.

  Then, the wafer 120 transferred from the position detection unit 300 to the holder table 362 by the wafer slider is placed on a plurality of lift pins. At this time, the mounting unit 360 aligns the wafer 120 and the wafer holder 190 while observing the wafer 120 and the wafer holder 190 with the observation device 364, and places the wafer 120 on the lift pins. Then, the wafer 120 is placed on the wafer holder 190 by lowering the lift pins.

  The holder table 362 is provided with power supply pins, and is connected to a power supply terminal provided on the back surface of the wafer holder 190 to supply power to the wafer holder 190. The wafer holder 190 supplied with power from the power supply terminal causes a potential difference on the wafer holding surface by the electrostatic chuck provided therein, and electrostatically attracts the wafer 120. The wafer 120 and the wafer holder 190 integrated in this way are called workpieces. The work formed by the preliminary aligner 130 is carried into the main aligner 140 by the robot arm 176.

  The aligner 140 is a device for aligning and overlaying a plurality of alignment marks formed on the wafer 120 of each workpiece with high accuracy, with two workpieces facing each other. The aligner 140 includes a fixed stage 141, a moving stage 142, a control unit 143, microscopes 144 and 145, and interferometers 146 and 147. Further, a shutter 148 and a heat insulating wall 149 are provided so as to surround the aligner 140.

  The fixed stage 141 is installed on the ceiling portion of the aligner 140, and holds the work downward in a fixed state. A workpiece held on the fixed stage 141 is called an upper workpiece, and a wafer holder 190 constituting the upper workpiece is called an upper wafer holder 191. The moving stage 142 holds the workpiece upward. And it is comprised so that a movement in an XY plane direction is possible, A workpiece | work is hold | maintained and conveyed. A workpiece placed on the moving stage 142 is called a lower workpiece, and a wafer holder 190 constituting the lower workpiece is called a lower wafer holder 192.

  The control unit 143 uses the microscope 144 installed adjacent to the fixed stage 141 and the microscope 145 installed adjacent to the moving stage 142 to set the alignment mark of the wafer 120 of the upper work and the alignment mark of the wafer 120 of the lower work. Observe. Then, the upper stage wafer 120 and the lower work wafer 120 are aligned with each other by precisely moving the moving stage 142 while monitoring the position thereof by the interferometers 146 and 147 with the alignment mark as a reference.

  At this time, the control unit 143 uses, for example, a global alignment method or the like that is statistically determined so that the amount of misalignment is minimized when a plurality of alignment marks formed on each of the two wafers are superimposed. To perform calculations. After the alignment is completed, the control unit 143 raises the lower work by the moving stage 142 and brings the bonding surface of the wafer 120 of the upper work and the wafer 120 of the lower work into contact with each other to superimpose them. Two superimposed workpieces are collectively called a workpiece pair.

  Since the aligner 140 is required to align the two wafers 120 with high accuracy in this way, the microscopes 144 and 145 are set at high magnification and the observation field of view is narrow. As a result, if the workpiece is loaded into the aligner 140 with the position of the wafer 120 being displaced, it takes time to align the position and causes a reduction in the overall throughput. In particular, when the positional deviation is large and the alignment mark of the wafer 120 is out of the observation field of view of the microscopes 144 and 145, it takes an extra time to search for the alignment mark.

  Further, when the position of the moving stage 142 is monitored using the interferometers 146 and 147 as in this embodiment, the adjustment range in the rotation direction is narrowed. For this reason, when the wafer 120 is displaced beyond the allowable adjustment range in the rotational direction of the moving stage 142, the alignment cannot be adjusted so that the alignment mark is within the observation field of view of the microscopes 144 and 145. It may not be possible. Therefore, the alignment of the wafer 120 is executed in advance by the preliminary aligner 130 so that the alignment mark of the wafer 120 falls within the imaging field of view of the microscopes 144 and 145 of the aligner 140.

  The work pair formed by the main aligner 140 is unloaded from the main aligner 140 by the robot arm 176 and placed on the transfer port 173 provided at the upper part of the separation mechanism 160 by the first transfer unit 171 or the second transfer unit 172. Is done. The first transport unit 171 and the second transport unit 172 travel independently on rails provided in parallel in the vertical direction. The first transfer unit 171 is positioned above the second transfer unit 172 and has a structure that can pass by while holding the wafer holder 190, the workpiece and the workpiece pair. The work pair placed on the delivery port 173 is carried into a load lock chamber 220 described later by the robot arm 175.

  The vacuum environment unit 202 includes a heat insulating wall 210, a load lock chamber 220, a robot arm 230, and a plurality of heating and pressing devices 240. The heat insulating wall 210 surrounds the vacuum environment unit 202 to maintain the internal temperature of the vacuum environment unit 202 and blocks heat radiation to the outside of the vacuum environment unit 202. Thereby, the influence which the heat of the vacuum environment part 202 has on the atmospheric environment part 102 can be suppressed. The robot arm 230 is a transfer device that transfers a work pair, and transfers the held work pair between the load lock chamber 220 and the heating and pressurizing device 240.

  The load lock chamber 220 includes shutters 222 and 224 that open and close alternately on the atmosphere environment unit 102 side and the vacuum environment unit 202 side. When the workpiece pair is carried from the atmospheric environment unit 102 to the vacuum environment unit 202, first, the shutter 222 on the atmospheric environment unit 102 side is opened, and the robot arm 176 carries the workpiece pair into the load lock chamber 220. Next, the shutter 222 on the atmosphere environment unit 102 side is closed, and the air in the load lock chamber 220 is exhausted to make a vacuum state.

  After the inside of the load lock chamber 220 is in a vacuum state, the shutter 224 on the vacuum environment unit 202 side is opened, and the robot arm 230 carries out the workpiece pair. By such a loading operation to the vacuum environment unit 202, the workpiece pair can be loaded into the vacuum environment unit 202 without leaking the internal atmosphere of the air environment unit 102 to the vacuum environment unit 202 side.

  Next, the robot arm 230 carries the unloaded workpiece pair into one of the plurality of heating and pressing devices 240. The heating / pressurizing device 240 heats and presses the workpiece pair. As a result, the wafer 120 loaded while being sandwiched between the wafer holders 190 is permanently bonded.

  The heating / pressurizing device 240 includes a main body for heating the work pair and a heating / pressurizing chamber in which the main body is disposed. The robot arm 230 is installed in the robot arm chamber. That is, the plurality of heating and pressurizing chambers, robot arm chambers, and load lock chambers 220 constituting the vacuum environment unit 202 are individually partitioned and the atmosphere can be adjusted separately. As shown in the drawing, the vacuum environment unit 202 includes a plurality of heating and pressurizing chambers and a load lock chamber 220 arranged in the circumferential direction with the robot arm chamber as the center.

  When the workpiece pair is carried out from the vacuum environment unit 202 to the atmospheric environment unit 102, the shutter 224 on the vacuum environment unit 202 side is first opened, and the robot arm 230 carries the workpiece pair into the load lock chamber 220. Next, the shutter 224 on the vacuum environment section 202 side is closed, and the shutter 222 on the atmosphere environment section 102 side is opened. Then, the workpiece pair is unloaded from the load lock chamber 220 by the robot arm 175.

  The work pair carried out from the load lock chamber 220 is carried into the separation mechanism 160, and the separation mechanism 160 takes out the bonded wafer that is sandwiched and bonded by the wafer holder 190. The bonded wafer is accommodated in the FOUP attached to the load port 115 by the first transfer unit 171 or the second transfer unit 172.

  FIG. 2 is a top view schematically showing the structure of the wafer 120. In the figure, the plane direction is the XY axis direction, and the gravity direction is the Z axis direction. In addition, the orientation when the wafer 120 is placed on the wafer holder 190 by the spare aligner 130 is shown. The wafer 120 is provided with a notch 123 indicating the crystal orientation of the wafer 120 in a part of the periphery thereof. The notch 123 here includes a notch and an orientation flat. In addition, for example, the circuit pattern 124 is formed on the wafer 120 in about several tens of shots to several hundred shots, but in the figure, the case where 22 circuit patterns 124 are formed is illustrated.

  A plurality of alignment marks 125 are formed around the circuit pattern 124 by a photolithography process. Here, the alignment mark 125 is formed in a cross shape. The orientation of the wafer 120 is adjusted by the preliminary aligner 130 so that the notch 123 is positioned at the end in the −Y direction when the wafer 120 is placed on the moving stage 142 of the aligner 140.

  FIG. 3 is a plan view schematically showing the upper wafer holder 191 that holds the wafer 120. The upper wafer holder 191 has a holder body 911 and a magnet unit 918. The holder body 911 is integrally formed of a highly rigid material such as ceramics or metal, and has a region for holding the wafer 120 on the surface thereof. This holding region is polished and has high flatness. The holding of the wafer 120 is performed by adsorption using an electrostatic force.

  Specifically, a potential difference is generated between the upper wafer holder 191 and the wafer 120 by applying a voltage to the electrostatic chuck embedded in the holder body 911 via a voltage application terminal provided on the back surface of the holder body 911. As a result, the wafer 120 is attracted to the upper wafer holder 191. The suction surface of the wafer 120 is the surface opposite to the surface on which the circuit pattern 124 is provided.

  The holder main body 911 is provided with an insertion hole 912. The insertion hole 912 is provided at a position along a line corresponding to the outer periphery of the wafer 120 when the wafer 120 is placed on the upper wafer holder 191. The lift pins included in the preliminary aligner 130 penetrate the insertion hole 912, so that the wafer 120 can be placed on the lift pins. The wafer 120 placed on the lift pins is placed on the wafer holder 190 as the lift pins descend. The holder main body 911 has a notch 916 at a part of the outer periphery thereof. The notch 916 is used as a reference in the preliminary aligner 130 when the wafer 120 is preliminarily aligned with the wafer holder 190.

  A plurality of magnet units 918 are arranged in an outer peripheral area outside the held wafer 120 on the surface holding the wafer 120. In the case of the figure, a total of six magnet units 918 are arranged every 120 degrees with two as one set.

  FIG. 4 is a plan view schematically showing the lower wafer holder 192 that holds the wafer 120. Constituent elements similar to those of the upper wafer holder 191 are assigned the same reference numerals as those of the upper wafer holder 191 and description thereof is omitted. The lower wafer holder 192 is different from the upper wafer holder 191 in that it has a suction unit 922 instead of the magnet unit 918.

  A plurality of suction units 922 are arranged in the outer peripheral area outside the held wafer 120 on the surface holding the wafer 120. In the case of the figure, a total of six suction units 922 are arranged every 120 degrees with two as one set. The attracting unit 922 is made of a magnetic material, and is disposed so as to correspond to the magnet unit 918 of the upper wafer holder 191. When the upper wafer holder 191 that holds the wafer 120 and the lower wafer holder 192 that holds the wafer 120 face each other and the magnet unit 918 and the attracting unit 922 act, the two wafers 120 are sandwiched in an overlapped state. Can be fixed.

  FIG. 5 is a perspective view schematically showing the structure of the position detection unit 300. The position detection unit 300 includes a pedestal unit 302, a stage 304, a control unit 306, three first illumination units 311, 312, and 313 as first illumination units, and three second illumination units 321 and 322 as second illumination units. 323, three third illumination units 331, 332, 333, 334 as third illumination units, three first imaging units 341, 342, 343 as first imaging units, and four first as imaging units Two imaging units 351, 352, 353, and 354 are provided.

  A stage 304 is installed on the pedestal portion 302, and the wafer 120 loaded by the robot arm 116 is placed on the stage 304. In the figure, a direction parallel to the mounting surface of the wafer 120 is described as an XY axis direction, and a direction perpendicular to the mounting surface is described as a Z axis direction. The stage 304 moves parallel to the XY directions. Further, the wafer is rotated with respect to the Z axis with the center point of the wafer placement surface as the center axis.

  The first illumination units 311, 312, and 313 are installed on the stage 304 and irradiate illumination light in a direction orthogonal to the wafer mounting surface. The first imaging units 341, 342, and 343 are installed on the ceiling of the position detection unit 300, and face the first illumination units 311, 312, and 313, respectively.

  The wafer 120 is placed by the robot arm 116 at a position where the edge thereof enters the imaging field of view of the first imaging units 341, 342, and 343. At this time, the illumination light emitted from the first illumination units 311, 312, and 313 is partially blocked by the wafer 120 and reaches the first imaging units 341, 342, and 343.

  The illumination light that has reached the first imaging units 341, 342, and 343 is photoelectrically converted by the control unit 306 and subjected to image processing. As a result, the control unit 306 acquires three captured image data corresponding to the three positions of the edge of the wafer 120. The control unit 306 detects the position of the wafer 120 based on the acquired three captured image data. Specific detection control will be described later.

  Each of the second illumination units 321, 322, and 323 irradiates illumination light downward through a half mirror that is configured integrally with the first imaging units 341, 342, and 343 and disposed in the lens barrel. . The illumination light emitted in the downward direction is adjusted to have a common optical path in the opposite direction to the illumination light directed from the first illumination units 311, 312, 313 to the first imaging units 341, 342, 343. Yes. A half prism may be used instead of the half mirror.

  At least a part of the illumination light emitted from the second illumination units 321, 322, and 323 reaches the edge of the wafer 120, and the scattered light at the edge part reaches the first imaging units 341, 342, and 343. The scattered light that has reached the first imaging units 341, 342, and 343 is subjected to photoelectric conversion by the control unit 306 and subjected to image processing. As a result, the control unit 306 acquires three captured image data corresponding to the three positions of the edge of the wafer 120. The control unit 306 detects the position of the wafer 120 based on the acquired three captured image data. Specific detection control will be described later.

  The third illumination units 331, 332, 333, and 334 provide slit images 335, 336, 337, and 338 as illumination light that illuminates the wafer 120 obliquely with respect to the mounting surface direction of the wafer 120. The slit images 335, 336, 337, and 338 have an elongated shape extending in the radial direction of the disk-shaped wafer 120, and the irradiation range includes a part of the edge of the wafer 120. The longitudinal direction of the slit images 335 and 338 is the X direction, and the longitudinal direction of the slit images 336 and 337 is the Y direction. The positions and irradiation directions of the third illumination units 331, 332, 333, and 334 are adjusted so as to illuminate the position where the edge is to come when the wafer 120 is correctly arranged with respect to the target position.

  The second imaging units 351, 352, 353, and 354 image a region including a part of the edge of the wafer 120 obliquely with respect to the surface direction of the wafer 120. The second imaging units 351, 352, 353, and 354 are installed at positions where the reflected light reflected by the wafer 120 reaches the illumination light irradiated by the third illumination units 331, 332, 333, and 334.

  At least a part of the illumination light emitted from the third illumination units 331, 332, 333, and 334 is reflected by the wafer 120, and the reflected light reaches the second imaging units 351, 352, 353, and 354. The reflected light that has reached the second imaging units 351, 352, 353, and 354 is subjected to photoelectric conversion and image processing by the control unit 306. As a result, the control unit 306 acquires four captured image data corresponding to the four positions of the edge of the wafer 120. The control unit 306 detects the position of the wafer 120 based on the acquired four captured image data. Specific detection control will be described later.

  FIG. 6 is a partial cross-sectional view schematically showing the configuration of the position detection unit 300 that images the edge of the wafer 120 illuminated by the first illumination unit 311 by the first imaging unit 341. The position of the cross section corresponds to AA in FIG. Illumination light emitted from the stage 304 side to the first imaging unit 341 side by the first illumination unit 311 is partially blocked by the wafer 120 and passes through the half mirror 326 to the first imaging unit 341. To reach. The reflected light from the half mirror 326 is not shown.

  FIG. 7 is a conceptual diagram illustrating captured image data 316 acquired by the control unit 306 performing image processing on an image captured by the first imaging unit 341. The control unit 306 obtains a binary image shown in FIG. 7 by performing image processing that binarizes the 8-bit grayscale image output from the first imaging unit 341 using a predetermined threshold. The hatched portion of the photographed image data 316 represents a portion blocked by the wafer 120, and the blocked portion is a black region, and the unblocked portion is a white region.

  As described above, the edge is illuminated vertically from the back side of the wafer 120, and the photographed image obtained by photographing the illuminated edge in the vertical direction from the front side of the wafer 120 is analyzed to measure the edge of the wafer 120. This method is called transmitted light measurement. Since the grayscale image by transmitted light is sharply separated from light and dark, an actual edge can be faithfully reproduced when binarized.

  FIG. 8 is a conceptual diagram illustrating an example of three pieces of captured image data 316, 317, and 318 acquired by performing image processing on the image captured by the first imaging unit by the control unit 306. The hatched portion corresponds to the portion where the wafer 120 blocks the illumination by the first illumination unit. A wafer 127 indicated by a broken line represents a position when the wafer 127 is correctly arranged at a target position, and a center position 128 represents a center point of the wafer 127. The circuit pattern 124 and the alignment mark 125 formed on the wafer 120 are not shown.

  Here, a method in which the control unit 306 detects the position of the wafer 120 based on the captured image data 316, 317, and 318 will be described. The controller 306 detects both the translational position and the rotational direction position as the position of the wafer 120. Here, the position of the wafer 120 in the translation direction is the X coordinate and the Y coordinate of the center point 126 of the wafer 120 with respect to the center position 128. The position in the rotation direction is an angle θ formed by the direction of the notch of the wafer 127 from the center position 128 and the direction of the notch 123 from the center point 126 of the wafer 120.

  The control unit 306 analyzes the three photographed image data 316, 317, and 318 and detects the coordinates of three points located on the edge of the wafer 120. First, the flow of calculating the coordinates of one point on the edge of the wafer 120 from the captured image data 316 will be described. A center point 811 represents the center of the imaging field of view of the first imaging unit 341. The coordinates of the center point 811 are previously grasped from the positional relationship with the center position 128 and stored in the storage unit provided in the control unit 306. When the wafer 120 is correctly placed at the target position, the edge of the wafer 120 is located at the center point 811.

  The control unit 306 calculates the coordinates of the intersection 813 between the straight line 812 connecting the center position 128 and the center point 811 and the edge of the wafer 120 with respect to the captured image data 316. Specifically, the position of the intersection 813 is specified by detecting a boundary point between a black area and a white area on the straight line 812. Then, the coordinates of the intersection point 813 are calculated by adding the relative coordinates of the center point 811 and the intersection point 813 to the coordinates of the center point 811. In this way, the control unit 306 acquires coordinates corresponding to one point on the edge of the wafer 120.

  Although the intersection 813 between the straight line 812 connecting the center position 128 and the center point 811 and the edge of the wafer 120 is detected here, the present invention is not limited to this. For example, other methods may be used as long as the coordinates of the boundary point between the black region and the white region are obtained such as detecting the boundary point between the black region and the white region along a straight line parallel to the Y axis from the center point 811. It doesn't matter.

  Similarly to the photographed image data 316, the coordinates of the intersection point 833 that is the intersection point of the straight line 832 connecting the center position 128 and the center point 831 and the edge of the wafer 120 are also acquired for the photographed image data 318. The captured image data 317 includes the notch 123 of the wafer 120, and the coordinates of a point that is a boundary point between the black region and the white region and is not on the notch 123 are calculated. Therefore, processing different from that of the captured image data 316 is performed. Apply.

  In the photographed image data 317, the center point 821 represents the center of the photographing field of view of the first imaging unit 342. The control unit 306 continuously detects a boundary point between the black region and the white region from the center point 821 toward the + X direction, and determines whether the boundary point is a point on the notch 123. Here, since the difference in the characteristic that the difference in the Y coordinate is small in the continuous boundary point on the edge other than the notch 123 appears compared to the continuous boundary point on the notch 123, the control unit 306 indicates the difference in the characteristic. By detecting, it is determined whether or not the point is on the notch 123.

  The control unit 306 confirms the difference in the Y coordinate between the boundary point detected from the center point 821 toward the + X direction and the boundary point detected immediately before, and the boundary point of the section showing a characteristic with a small difference. Get the coordinates. Then, the coordinates corresponding to one point on the edge of the wafer 120 are acquired by adding the acquired coordinates and the relative coordinates of the center point 821 to the coordinates of the center point 821.

  Through the above processing, three coordinates corresponding to three points on the edge of the wafer 120 are acquired. The control unit 306 calculates a center coordinate of a circle passing through the three points by applying a known calculation method to the obtained three point coordinates, thereby obtaining the coordinates of the center point 126 of the wafer 120 having a circular shape. get.

  Next, a method for detecting the position of the wafer 120 in the rotation direction will be described. The notch 123 of the wafer 120 has an isosceles triangle shape symmetrical to the center line of the wafer 120, and when the wafer 120 is correctly placed at the target position, the center line is parallel to the Y axis. Is provided. Therefore, the position in the rotation direction of the wafer 120 carried into the position detection unit 300 corresponds to the inclination of the center line of the notch 123 with respect to the Y axis.

  The controller 306 virtually forms an inscribed circle 823 inscribed in the notch 123 with respect to the captured image data 317 first. Next, for the two normal lines of the notch 123 and the inscribed circle 823, the coordinates of the intersection 824 are calculated. Then, the coordinates of the intersection point 824 are acquired by adding the relative coordinates of the intersection point 824 to the center point 821 to the coordinates of the center point 821. A straight line 825 connecting the coordinates of the intersection point 824 and the center point 126 of the wafer 120 becomes the center line of the notch 123. The control unit 306 calculates an angle θ formed by the straight line 822 and the straight line 825 connecting the center position 128 and the center point 821 as the position in the rotation direction of the wafer 120.

  The flow of detecting the position of the wafer 120 by performing transmitted light measurement using the first illumination unit and the first imaging unit is as described above. Here, when the detection target is a single-layer wafer, the position of the wafer 120 can be detected by transmitted light measurement. However, when the object to be detected is a laminated wafer, and the outer shape of the upper wafer is smaller than that of the lower wafer, the edge of the upper wafer cannot be observed by transmitted light measurement. When the object to be detected is a laminated wafer, the aligner 140 performs alignment with reference to the alignment mark 125 formed on the uppermost wafer. However, in the transmitted light measurement, the position of the uppermost wafer cannot be detected correctly. There is a problem.

  On the other hand, according to the detection control by the second illumination unit and the first imaging unit, the edge of the uppermost wafer can be directly observed, and the position of the uppermost wafer can be detected. In the present embodiment, an example in which an epi-illumination dark field optical system is employed will be described as detection control by the second illumination unit and the first imaging unit. FIG. 9 is a partial cross-sectional view schematically showing a configuration of the position detection unit 300 in which the edge of the wafer 120 illuminated by the second illumination unit 321 is imaged by the first imaging unit 341.

  Here, a case where a laminated wafer 901 in which an upper wafer 121 is laminated on a lower wafer 122 is arranged as a detection target wafer is illustrated. After the upper wafer 121 is laminated with the lower wafer 122, the opposite surface side of the bonding surface is polished and is thinner than the lower wafer 122. The position of the cross section corresponds to the position AA in FIG.

  The second illumination unit 321 is provided with a ring-shaped diaphragm 325 having a ring-shaped opening, and the ring-shaped illumination light that has passed through the ring-shaped diaphragm 325 reaches the half mirror 326. The ring-shaped illumination light is reflected by the half mirror 326 and illuminates the upper wafer 121 obliquely with respect to the wafer placement surface from the top to the bottom. Illumination light 327 illustrates part of the illumination light. Then, the regular reflection light 328 regularly reflected by the upper wafer 121 is blocked by the aperture stop 345 having a circular opening, and the scattered light 329 at the edge of the upper wafer 121 reaches the first imaging unit 341.

  The control unit 306 binarizes the grace case image output from the first imaging unit 341, whereby a binary image in which only the edge portions of the upper wafer 121 and the lower wafer 122 are white areas and the other areas are black areas. To get. Since the edges of the upper wafer 121 and the lower wafer 122 are recognized by the scattered light, the edges can be detected with high accuracy even when the step between the upper wafer 121 and the lower wafer 122 is small. FIG. 10 is a conceptual diagram showing the captured image data 324 acquired by the control unit 306.

  As shown in the photographed image data 324, the edges of the upper wafer 121 and the lower wafer 122 can be recognized by the detection control by the second illumination unit and the first imaging unit. In this way, a measurement method for measuring the edge of the uppermost wafer by illuminating the mounting surface of the laminated wafer 901 from the surface side of the laminated wafer 901 and receiving the scattered light from the surface side of the laminated wafer 901 is provided. This is called first reflected light measurement.

  According to the first reflected light measurement, the uppermost edge of the laminated wafer can be measured. The edge of the uppermost wafer of the laminated wafer is often in an R shape before being polished by the polishing apparatus, and becomes an D shape in which the upper part is a flat plate by polishing. Since the D-shaped edge whose upper part is a flat plate is in a state in which contrast easily occurs with the lower wafer, the edge can be accurately detected when the first reflected light measurement is applied.

  In other words, applying the first reflected light measurement to a laminated wafer in which the top wafer is polished and the shape of the edge is a D shape with a flat top is simply to measure the edge of the top wafer. In addition to the effect that it can be performed, the effect that the edge of the uppermost wafer can be detected with high accuracy may be obtained.

  The method for detecting the position of the upper wafer 121 based on the three photographed image data corresponding to the three positions of the edge of the upper wafer 121 acquired by the first reflected light measurement is the same as the transmitted light measurement. The description is omitted here. In the first reflected light measurement, the position of the wafer 120 can be detected even when the target is not a laminated wafer but a single layer wafer. However, if the detection target edge has an R shape, for example, it is difficult to produce a difference in contrast between the edges, and it may be difficult to accurately grasp the edge in the first reflected light measurement. Therefore, when a single-layer wafer is to be detected, it is desirable to preferentially apply transmitted light measurement rather than first reflected light measurement.

  As described above, in the first reflected light measurement, when the detection target is a laminated wafer, the position of the uppermost wafer can be detected. However, for example, if the uppermost wafer 120 is polished by the polishing apparatus and the step difference from the lower wafer is small, it is difficult to obtain only the scattered light of the edge, and the edge of the uppermost wafer 120 is accurately determined. It may not be possible to grasp. In such a case where the level difference between the uppermost wafer 120 and the lower wafer is small, detection control by the third illumination unit and the second imaging unit is effective.

  FIG. 11 is a perspective view schematically showing a configuration of the position detection unit 300 that images the edge of the laminated wafer 1101 illuminated by the third illumination unit by the second imaging unit. The position detection target is the position of the upper wafer 1102 of the laminated wafer 1101 in which the upper wafer 1102 is laminated on the lower wafer 1103.

  The third illumination units 331, 332, 333, and 334 form slit images 1110, 1120, 1130, and 1140 as illumination light that illuminates the laminated wafer 1101 obliquely with respect to the plane direction of the laminated wafer 1101. Are captured by the second imaging units 351, 352, 353, and 354. Then, the control unit 306 detects four absolute coordinates corresponding to four points on the edge of the upper wafer 1102 and the position of the upper wafer 1102 in the rotation direction based on the photographed image, so that the position of the upper wafer 1102 is detected. Is detected. In this case as well, the center position of the upper wafer 1102 when the upper wafer 1102 is correctly placed at the target position is used as a coordinate reference point.

  FIG. 12 is a conceptual diagram of the captured image data 1200 including the edge of the upper wafer 1102 output from the second imaging unit 351. The upper wafer reflected image 1202 in the captured image data 1200 is an image of a portion of the slit image 1110 that is reflected by the upper wafer 1102. On the other hand, the lower wafer reflected image 1203 is an image of a portion of the slit image 1110 reflected by the lower wafer 1103. Actually, the image data has lower brightness in the order of the upper wafer reflection image 1202, the lower wafer reflection image 1203, and the other regions, but for the sake of explanation, the higher brightness portion is illustrated as a darker image. .

  Since there is a height difference between the upper wafer 1102 and the lower wafer 1103, a stepped portion E exists between the upper wafer reflected image 1202 and the lower wafer reflected image 1203. Since the position of the stepped portion E corresponds to the position of the edge of the upper wafer 1102, the control unit 306 identifies the position of the edge of the upper wafer 1102 by analyzing the position of the stepped portion E.

  Specifically, the control unit 306 first identifies a boundary line between the upper wafer reflected image 1202 and another region by recognizing a difference in brightness in the selection window 1204. Then, the boundary line is identified while moving the selection window 1204 to the left, and a step where the vertical position of the boundary line is shifted downward is a step that is a boundary between the upper wafer reflected image 1202 and the lower wafer reflected image 1203. Recognized as the position of the part E.

  The control unit 306 stores in advance data that associates coordinates in the captured image data 1200 with absolute coordinates based on the size of the slit light to be irradiated and the optical magnification of the second imaging unit 351, and the like. The absolute coordinates of one point on the recognized stepped portion E are acquired. Here, the absolute coordinate of the intersection 1205 is acquired from the Y coordinate corresponding to the upper boundary line of the upper wafer reflected image 1202 and the X coordinate corresponding to the stepped portion E.

  The control unit 306 applies the same method to the slit images 1110, 1130, and 1140 acquired by the second imaging units 351, 353, and 354 so that four absolute coordinates corresponding to four points on the edge of the upper wafer 1102 are obtained. To get. Then, by applying a known calculation method to the absolute coordinates of three of the four acquired points and calculating the center coordinates of a circle passing through the three points, the center point 126 of the upper wafer 1102 having a circular shape is obtained. Get the coordinates of. The controller 306 acquires the coordinates of the center point 126 of the upper wafer 1102 by executing this center coordinate calculation process for three different points and taking the average value of the calculated center coordinates.

  Next, a method for detecting the position of the notch of the upper wafer 1102 in the rotation direction will be described. The position detection unit 300 detects a plurality of boundary points by observing the cutout and its periphery with the second imaging unit 352 while moving the laminated wafer 1101 by the stage 304. FIG. 13 is a conceptual diagram showing a plurality of boundary points detected by the control unit 306. In this example, nine boundary points from point A to point I are detected.

  Since the size of the notch of the upper wafer 1102 is known, the control unit 306 detects the boundary points at intervals sufficient to specify the shape of the notch, thereby removing the notch of the upper wafer 1102. Can be identified. For example, the notch of the upper wafer 1102 can be specified by detecting boundary points at intervals as shown in the figure. The control unit 306 virtually forms an inscribed circle with respect to the notch, and calculates the angle with respect to the Y axis of the straight line connecting the intersection of the normal line and the center point 126, thereby rotating the upper wafer 1102. The position of is detected.

  In this way, the slit wafer is irradiated obliquely with respect to the mounting surface of the laminated wafer so as to include a part of the edge of the upper wafer, and the reflected light is received on the surface side of the laminated wafer to thereby remove the edge of the upper wafer. A measurement method for photographing the region to be included and analyzing the position of the step included in the photographed image to measure the edge of the upper wafer is called second reflected light measurement. The position detection unit 300 can detect the position of the uppermost wafer of the laminated wafers by measuring the second reflected light.

  Next, a flow of position detection processing by the position detection unit 300 according to the present embodiment will be described. As described above, the position detection unit 300 according to the present embodiment is configured to execute a plurality of different detection controls. Then, the position detection unit 300 switches the detection control according to a predetermined condition and detects the position of the detection target wafer 120. FIG. 14 is a flowchart showing a flow of position detection control executed by the position detection unit 300.

  In step S <b> 1401, the robot arm 116 carries the wafer 120 into the position detection unit 300. The robot arm 116 arranges the wafer 120 so that the edge of the wafer 120 enters the imaging field of view of the three first imaging units 341, 342, and 343. The robot arm 116 stores in advance a movement amount for the edge of the wafer 120 to enter the imaging field of view of the first imaging units 341, 342, and 343, and transports the wafer 120 according to this movement amount, thereby allowing the wafer 120 to move. Can fit within the field of view. The control unit 306 and the robot arm 116 may be linked so that the wafer 120 is moved so that the edge of the wafer 120 falls within the imaging field of view while checking the captured image acquired by the first imaging unit. good.

  In step S1402, the control unit 306 determines whether the loaded wafer 120 is a single layer wafer or a laminated wafer. The loaded wafer 120 is managed by the control unit 110, and the control unit 306 refers to information managed by the control unit 110 to determine whether the loaded wafer is a single layer wafer or a laminated wafer. Can be judged. For example, a measurement device that measures the thickness of the wafer 120 may be provided separately, and the thickness of the wafer 120 measured by the measurement device may be determined to determine whether the wafer is a single-layer wafer or a laminated wafer. .

  If the controller 120 determines in step S1402 that the loaded wafer 120 is a single layer wafer, the process advances to step S1403. If the controller 120 determines that the wafer 120 is not a single layer wafer but a stacked wafer, the process proceeds to step S1404. move on. In step S1403, the control unit 306 detects the position of the wafer 120 by the above-described transmitted light measurement.

  In step S1404, the control unit 306 determines whether the interval between the surface of the uppermost wafer of the stacked wafers and the surface of the next lower wafer is larger or smaller than a predetermined threshold value. When the interval is so small that the edge of the wafer cannot be recognized by the first reflected light measurement, it is desirable to detect the position by the second reflected light measurement instead of the first reflected light measurement. On the other hand, when the interval is large enough to recognize the edge of the wafer by the first reflected light measurement, it is preferable to execute the first reflected light measurement that can detect the position in a shorter time than the second reflected light measurement.

  Therefore, in step S1404, the control unit determines whether or not the distance between the surface of the uppermost wafer and the surface of the next lower wafer exceeds the size at which the edge of the wafer can be recognized by the first reflected light measurement. 306 determines. The control unit 110 manages the interval between the surface of the uppermost wafer and the surface of the next lower wafer, and the control unit 306 communicates with the control unit 110 to acquire information on the interval. . The control unit 110 can acquire and manage information indicating a distance between the surface of the uppermost wafer of the laminated wafer and the surface of the wafer below it from a polishing apparatus that polishes the laminated wafer, for example. .

  If the control unit 306 determines in step S1404 that the distance between the uppermost wafer surface and the surface of the next lower wafer is greater than or equal to the threshold value, the process proceeds to step S1405. The process proceeds to S1406. In step S1405, the control unit 306 detects the position of the wafer 120 by the first reflected light measurement. In step S1406, the control unit 306 detects the position of the wafer 120 by measuring the second reflected light.

  In step S1407, based on the measured position of the wafer 120, the stage 304 adjusts the position of the wafer 120 so that the position of the wafer 120 matches the target position. The wafer 120 whose position has been adjusted in this way is transferred onto the holder table 362 by the wafer slider of the preliminary aligner 130 and placed on the wafer holder 190.

  In the above flowchart, in step S1404, it is determined whether or not the interval between the surface of the uppermost wafer of the laminated wafer and the surface of the wafer below it is equal to or greater than a threshold value, but another determination is made. You may control as follows. For example, it is determined whether or not a filler such as a resin is attached to a stepped portion formed by the uppermost wafer and the lower wafer of the laminated wafer.

  When a bump is formed on a wafer and the wafers are stacked, a resin may be sealed between the wafers. If this resin adheres to the outer periphery of the uppermost wafer, there will be no step between the edge of the uppermost wafer and the lower wafer, and there will be no gap between the resin and the lower wafer. A step will occur. As a result, when the second reflected light measurement is executed, the edge of the uppermost wafer cannot be detected correctly.

  On the other hand, when the first reflected light measurement is executed, the edge of the uppermost wafer and the boundary between the resin adhering to the edge can be recognized, so the resin is adhering to the edge of the uppermost wafer. It is desirable to perform the first reflected light measurement instead of the second reflected light measurement. Therefore, it is determined whether or not the resin is attached to the edge of the uppermost wafer, and if it is determined that the resin is attached, the process proceeds to step S1405 to execute the first reflected light measurement, and the resin is If it is determined that it is not attached, the process proceeds to step S1406, and control can be performed so as to execute the second reflected light measurement.

  In the above flowchart, the case where the process proceeds to step S1404 when the wafer is determined to be a laminated wafer in step S1402 has been described as an example, but the present invention is not limited thereto. If it is determined in step S1402 that the wafer is a laminated wafer, it is next determined whether or not the transmitted light measurement can be applied even to the laminated wafer. If applicable, the process proceeds to step S1403. If not, the process proceeds to step S1404. You may control as follows.

  Whether or not transmitted light measurement can be applied even if the detection target is a laminated wafer can be determined by whether or not two conditions are met. The first condition is whether or not there is a possibility that a predetermined allowable deviation amount is exceeded with respect to the history regarding the lamination accuracy of the laminated wafer to be detected. In some cases, the laminated wafers are laminated with their positions shifted depending on the accuracy of the equipment to be laminated. In that case, the positions of the stacked wafers do not match.

  As a result, even if the wafer is aligned based on the position of the wafer other than the uppermost wafer, the alignment mark 125 formed on the uppermost wafer may not be aligned. However, in this case, if the amount of deviation is small enough to fit within the observation field of the microscope of the present aligner 140, the alignment mark 125 will fit within the observation field of the microscope when loaded into the present aligner 140. become. Therefore, the control unit 306 determines whether or not there is a possibility that a predetermined tolerance is exceeded with respect to the history regarding the stacking accuracy of the stacked wafer to be detected. The history information regarding the stacking accuracy of the wafer 120 is managed by the control unit 110, and the control unit 306 can make a determination by referring to the history information managed by the control unit 110.

  The second condition is whether or not the position of any one of the stacked wafers can be detected. As described above, if the first condition is satisfied, any position of the stacked wafers can be detected and aligned, and when it is loaded into the aligner 140, it is aligned within the observation field of the microscope. The mark 125 can be accommodated. Whether or not the position of any one of the stacked wafers can be detected can be determined as follows, for example.

  FIG. 15 is a diagram illustrating an example in which wafer position detection is performed by measuring transmitted light for a laminated wafer. As for the two captured image data 1510 and 1520, the control unit 306 binarizes an image in which a part of the edge including the cutout of the laminated wafer illuminated by the first illumination unit 312 is captured by the first imaging unit 342. Represents photographed image data acquired. In the figure, the upper wafer 1501 and the lower wafer 1502 are shown separately for the sake of explanation, but in actuality, the hatched portions are all black regions.

  The shape and size of the notch are known, and the control unit 306 stores graphic data corresponding to the shape and size of the notch in the storage unit in advance. Then, the control unit 306 inscribes the notch of one wafer like the photographed image data 1510 by performing pattern matching on the photographed image data 1510 and 1520 with the notch graphic data stored in the storage unit. It is determined whether or not the inscribed circle 1511 can be formed. In the case of the captured image data 1510, it is possible to form an inscribed circle that is inscribed in the notch of one wafer, so that it is determined that the position of at least one of the wafers laminated on the laminated wafer can be detected correctly. Can do.

  On the other hand, in the case of the captured image data 1520, only a small cut shape can be recognized with respect to the cutout graphic data stored in the storage unit, so that it can be determined that two wafers overlap each other at the cutout portion. Even if the inscribed circle 1521 is formed with respect to this notch, an inscribed circle inscribed in the notches of the two wafers is formed, and both the positions of the upper wafer 1501 and the lower wafer 1502 can be detected correctly. I can't. Therefore, in the case of the captured image data 1520, the control unit 306 determines that the position of any of the stacked wafers cannot be detected correctly.

  Even when the detection target is a laminated wafer, the transmitted light measurement can be applied when the two conditions described above are satisfied. Therefore, after determining that the wafer is a laminated wafer in step S1402 by the control unit 306, it is determined whether or not the transmitted light measurement can be applied under two conditions. If applicable, the process proceeds to step S1403. Can implement the control of proceeding to step S1404.

  FIG. 16 is a flowchart showing a flow of position detection control executed by the position detection unit 300, which is different from the above-described flowchart. In step S <b> 1601, the robot arm 116 carries the wafer 120 into the position detection unit 300. The robot arm 116 places the wafer 120 at a position where the edge of the wafer 120 enters within the field of view of the first imaging units 341, 342, and 343. In step S1602, the position of the wafer 120 is detected by transmitted light measurement.

  In step S1603, the control unit 306 determines whether the position detection result of the wafer 120 is an error. The control unit 306 determines that the detection result is an error when the position of the wafer 120 cannot be detected or when the tolerance exceeds a preset allowable range.

  If the control unit 306 determines that the detection result is an error in step S1603, the process proceeds to step S1604. If the detection result is not determined to be an error, the process proceeds to step S1609. In step S1604, the control unit 306 detects the position of the wafer 120 by the first reflected light measurement. In step S1605, the control unit 306 determines whether the position detection result of the wafer 120 is an error.

  If the control unit 306 determines that the detection result is an error in step S1605, the process proceeds to step S1606. If the error is not determined, the process proceeds to step S1609. In step S1606, the control unit 306 detects the position of the wafer 120 by the second reflected light measurement. In step S1607, it is determined whether the position detection result of the wafer 120 is an error.

  If the control unit 306 determines that the detection result is an error in step S1607, the process proceeds to step S1608, and if it is not determined to be an error, the process proceeds to step S1609. In step S1608, an error is detected in all of the transmitted light measurement, the first reflected light measurement, and the second reflected light measurement. Therefore, the robot arm 116 removes the wafer 120 from the position detection unit 300 under the control of the control unit 306. Take it out. The unloaded wafer 120 is returned to the FOUP by the robot arm 116.

  In step S1609, based on the measured position of the wafer 120, the position is adjusted by the stage 304 so that the position of the wafer 120 matches the target position. The wafer 120 whose position has been adjusted in this way is transferred onto the holder table 362 by the wafer slider of the preliminary aligner 130 and placed on the wafer holder 190.

  In the above flowchart, an example is described in which position detection is performed in the order of transmitted light measurement, first reflected light measurement, and second reflected light measurement. However, the present invention is not limited to this, and the order may be changed. Absent. For example, it may be controlled to execute position detection by the first reflected light measurement in step S1602.

  When the carried-in wafer is a single layer wafer, as described above, the transmitted light measurement can specify the edge more accurately than the first reflected light measurement. However, even when the position of the single-layer wafer is detected by the first reflected light measurement, which is less accurate than the transmitted light measurement, the position can be detected with an accuracy that the alignment mark is within the observation field of the microscope of the aligner 140. If it is, the detection result by a 1st reflected light measurement is employable. Therefore, position detection by first reflected light measurement is executed in step S1602, and in step S1603, it is determined whether the detection result is an accuracy with which the alignment mark is within the observation field of the microscope of the aligner 140. To control. Further, a measurement method for detecting the position of the wafer by bringing the notch of the wafer into contact with a physical positioning pin may be added to the flowchart.

  FIG. 17 is a flowchart showing a flow of position detection control executed by the position detection unit 300, which is different from the flowchart described above. Here, a process flow of the position detection unit 300 in a lot process in which a plurality of sets are formed by repeating the process of superposing the upper wafer 121 and the lower wafer 122 to form one set will be described. In this case, a group of wafers to be subjected to the same process is assumed to be a wafer of the same lot.

  In step S <b> 1701, the robot arm 116 carries the wafer 120 into the position detection unit 300. In step S1702, the control unit 110 determines whether or not it is the first wafer 120 of the same lot. If the controller 110 determines that the first wafer 120 is in the same lot, the process proceeds to step S1703. If the controller 110 determines that the first wafer 120 is not in the same lot, the process proceeds to step S1708.

  In step S <b> 1703, the position detection unit 300 detects the position of the wafer 120 by executing three measurement controls of transmitted light measurement, first reflected light measurement, and second reflected light measurement. The execution order of the three measurement controls may be other orders. The position detection unit 300 acquires three detection results by executing three measurement controls. The three detection results are stored in the storage unit 111.

  In step S1704, the position detection unit 300 adjusts the position of the wafer 120 according to at least one of the three acquired position detection results. For example, the adjustment may be performed according to one of the three position detection results, or may be performed by taking an average of the three position detection results. After the position adjustment, the position detection unit 300 places the wafer 120 on the wafer holder 190 to form a workpiece.

  In step S1705, the robot arm 176 conveys the work formed by the position detection unit 300 to the aligner 140. The aligner 140 observes the alignment marks of the wafer 120 with the microscopes 144 and 145, detects the position of the wafer 120 with high accuracy, and executes the alignment of the wafer 120. At this time, the control unit 110 stores the detection result of the position of the wafer 120 detected with high accuracy in the storage unit 111.

  In step S1706, the control unit 110 compares the detection results by the main aligner 140 stored in the storage unit 111 with the three detection results by the position detection unit 300, and determines the detection result having the smallest difference. And the measurement control which measured the detection result with the smallest difference is judged as selection measurement control. Thereafter, the process proceeds to step S1709.

  Next, the case where it is determined in step S1702 that the wafer is not the first wafer of the same lot will be described. In step S1707, the position detection unit 300 detects the position of the wafer 120 by the measurement control selected in step S1706. The wafers 120 in the same lot are a group of wafers to be subjected to the same process as described above.

  Here, the same process can be, for example, an overlay process when the number of stacked wafers to be overlapped is the same. That is, in the case of the process of superposing the upper wafer as a single layer wafer and the lower wafer as a laminated wafer in which three wafers are laminated, all the upper wafers in the same lot are single layer wafers, and all the lower wafers are laminated with three wafers. It is a laminated wafer. Thus, since the conditions of the wafers 120 in the same lot are the same, the measurement control that outputs the optimum detection result for the first wafer 120 in the same lot is also optimal for other wafers 120 in the same lot. You can expect to be there.

  In step S1708, the position of the wafer 120 is adjusted according to the detection result acquired in step S1707. In step S1709, the robot arm 176 conveys the work formed by the position detection unit 300 to the aligner 140. In step S1710, control unit 110 determines whether or not processing for the same lot has been completed. If it is determined that the process for the same lot has not been completed, the process returns to step S1701, and if it is determined that the process for the same lot has been completed, the process ends. Since the wafers 120 in the same lot have the same stacking conditions as described above, the position of each wafer 120 can be detected by the optimum measurement control among a plurality of measurement controls by processing according to the flow described above. Can do.

  In the flowchart shown in FIG. 17, the wafers 120 in the same lot are illustrated as having the same number of layers, but the present invention is not limited thereto. For example, a wafer heated and pressurized by the same heating and pressing apparatus 240, a wafer carried out from the same FOUP, a wafer exposed by the same exposure apparatus, and the like may be used as conditions.

  In the above embodiment, the case where the dark field optical system is employed as the first reflected light measurement has been described as an example, but a bright field optical system may be employed. When the bright-field optical system is employed, the control unit 110 detects the edge of the upper wafer 121 by acquiring image data with a dark edge by the geometric shadow of the edge of the upper wafer 121. By adopting the bright field optical system, the configurations of the second illumination unit and the second imaging unit can be simplified as compared with the case where the dark field optical system is employed.

  Moreover, in the said embodiment, the position detection part 300 is one apparatus provided with a 1st illumination part, a 2nd illumination part, a 3rd illumination part, a 1st imaging part, and a 2nd imaging part, transmitted light measurement, 1st Although an example is described in which the reflected light measurement and the second reflected light measurement can be performed, the present invention is not limited to this. A dedicated device that performs the transmitted light measurement, the first reflected light measurement, and the second reflected light measurement may be separately provided, and the position detection unit 300 may be configured to switch the device to be used.

  In the above-described embodiment, the example in which the wafer 120 is mounted on the wafer holder 190 and carried into the main aligner 140 has been described. However, the present invention is not limited thereto, and the wafer 120 is directly carried into the main aligner 140 without using the wafer holder 190. You may comprise so that it may do. In that case, after the position is adjusted by the position detection unit 300, the wafer 120 is carried into the aligner 140 by the robot arm 176.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The execution order of each process such as operation, procedure, step, and stage in the apparatus and method shown in the claims, the description, and the drawings is clearly indicated as “before”, “prior”, etc. It should be noted that, unless the output of the previous process is used in the subsequent process, it can be realized in any order. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 100 Overlay apparatus, 101 housing | casing, 102 atmospheric environment part, 110 control part, 111 memory | storage part, 112 EFEM, 113, 114, 115 load port, 116 robot arm, 120 wafer, 121 upper wafer, 122 lower wafer, 123 notch , 124 circuit pattern, 125 alignment mark, 126 center point, 127 wafer, 128 center position, 130 spare aligner, 140 aligner, 141 fixed stage, 142 moving stage, 143 control unit, 144, 145 microscope, 146, 147 interferometer 148 shutter, 149 heat insulation wall, 150 holder rack, 160 separation mechanism, 171 first transfer unit, 172 second transfer unit, 173 delivery port, 175, 176 robot arm, 190 wafer wafer 191 Upper wafer holder, 192 Lower wafer holder, 202 Vacuum environment section, 210 Heat insulation wall, 220 Load lock chamber, 222, 224 Shutter, 230 Robot arm, 240 Heating and pressing device, 300 Position detection section, 302 Base section, 304 Stage , 306 Control unit, 311, 312, 313 First illumination unit, 316, 317, 318 Photographed image data, 321, 322, 323 Second illumination unit, 324 Photographed image data, 325 Ring-shaped aperture, 326 Half mirror, 327 Illumination Light, 328 Regular reflection light, 329 Scattered light, 331, 332, 333, 334 Third illumination unit, 335, 336, 337, 338 Slit image, 341, 342, 343 First imaging unit, 345 Aperture stop, 351, 352 353, 3 54 Second imaging unit, 360 mounting portion, 362 holder table, 364 observer, 811 center point, 812 straight line, 813 intersection point, 821 center point, 823 inscribed circle, 824 intersection point, 825 straight line, 831 center point, 832 straight line, 833 Intersection, 901 Laminated wafer, 911 Holder body, 912 Insertion hole, 918 Magnet unit, 922 Adsorption unit, 1101 Laminated wafer, 1102 Upper wafer, 1103 Lower wafer, 1110, 1120, 1130, 1140 Slit image, 1200 Photographed image data, 1202 Upper wafer reflection image, 1203 Lower wafer reflection image, 1204 Selection window, 1205 Intersection, 1501 Upper wafer, 1502 Lower wafer, 1510 Photographed image data, 1511 Inscribed circle, 1520 Photographed image data 1521 inscribed circle

Claims (12)

Stage,
A detection unit for detecting a position of a wafer disposed on the stage;
A position detection apparatus comprising: a control unit that controls the detection unit by switching a plurality of different detection controls for detecting the position of the wafer according to a predetermined condition. The detection unit illuminates the edge of the wafer from the back side of the wafer that is the stage side, and the second illumination that illuminates the edge of the wafer from the surface side opposite to the back side. And a first imaging unit having a region including the edge as an observation field,
The plurality of detection controls include first detection control for detecting the position of the wafer by imaging the edge illuminated by the first illumination unit by the first imaging unit, and illumination by the second illumination unit. The position detection apparatus according to claim 1, further comprising: a second detection control that images the edge that has been captured by the first imaging unit and detects the position of the wafer. The first illuminating unit and the second illuminating unit are arranged so that directions of the respective illumination lights are orthogonal to the wafer,
The detection unit includes a third illumination unit that illuminates the edge from the surface side at an angle different from that of the second illumination unit, and an area including the edge as an observation field, and the edge is illuminated by the third illumination unit. A second imaging unit for imaging
3. The position according to claim 2, wherein the plurality of detection controls include third detection control in which the edge illuminated by the third illumination unit is imaged by the second imaging unit and the position of the wafer is detected. Detection device.   The control unit detects the position of the wafer by the first detection control when the wafer is a single-layer wafer consisting of a single wafer, and when the wafer is a laminated wafer in which a plurality of wafers are laminated. The position detection apparatus according to claim 2, wherein the position of the wafer is detected by detection control other than the first detection control.   The controller detects the position of the wafer by the first detection control when the wafer is a single-layer wafer consisting of a single wafer, and the wafer is a laminated wafer in which a plurality of wafers are laminated, When the distance between the surface of the uppermost wafer of the laminated wafer and the surface of the wafer arranged below the uppermost wafer is larger than a threshold, the position of the wafer is detected by the second detection control, The position detection device according to claim 3, wherein the position of the wafer is detected by the third detection control when the wafer is the laminated wafer and the interval is smaller than a threshold value.   The control unit detects the position of the wafer by the first detection control when the wafer is a single-layer wafer consisting of a single wafer, and the wafer is a laminated wafer in which a plurality of wafers are laminated, When the filler adheres to the stepped portion formed by the uppermost wafer and the wafer below it, the position of the wafer is detected by the second detection control, and the wafer is the laminated wafer, The position detection device according to claim 3, wherein the position of the wafer is detected by the third detection control when a filler is not attached to a step portion formed by the wafer and the wafer under the wafer.   4. The position detection according to claim 1, wherein when the detection result of one detection control is an error, the control unit switches to another detection control and detects the position of the wafer again. 5. apparatus.   The controller detects the position of the wafer by the first detection control when determining that there is no possibility of exceeding a predetermined allowable deviation amount with respect to the history regarding the stacking accuracy of the wafer. 3. The position detection apparatus according to claim 2, wherein when it is determined that the allowable deviation amount may be exceeded, the position of the wafer is detected by the second detection control.   The control unit controls the detection unit to execute the plurality of detection controls for one wafer, and based on a plurality of detection results detected by executing the plurality of detection controls, The detection unit is controlled so that one detection control is selected from a plurality of detection controls and the selected one detection control is executed on another wafer in the same lot as the one wafer. 4. The position detection device according to any one of items 3. Stage,
A detection unit for detecting a position of a wafer disposed on the stage;
A control unit that controls the detection unit by switching a plurality of different detection controls for detecting the position of the wafer according to a predetermined condition;
An alignment unit that aligns the wafer based on the position of the wafer detected by the detection unit under the control of the control unit;
And a superimposing unit that superimposes two wafers aligned by the alignment unit. A position detection method for controlling a position detection apparatus including a detection unit for detecting the position of a wafer arranged on a stage,
A selection step of selecting one detection control from a plurality of different detection controls for detecting the position of the wafer according to a predetermined condition;
And a detection step of detecting the position of the wafer by detection control selected in the selection step. A device manufacturing method manufactured by superposing a plurality of wafers,
The step of superimposing the plurality of wafers includes:
According to a predetermined condition, at least one detection control is selected from a plurality of different detection controls for detecting the position of the first wafer, which is one of the plurality of wafers, and the first detection control is used to select the first control. A first detecting step for detecting the position of one wafer;
According to a predetermined condition, at least one detection control is selected from a plurality of different detection controls for detecting the position of the second wafer, which is one of the plurality of wafers, and the first detection control is used to select the first detection control. A second detection step for detecting the position of two wafers;
The first wafer and the second wafer are respectively placed on opposite stages, and the position of the first wafer detected in the first detection step and the detection in the second detection step are detected. A device manufacturing method comprising: an overlapping step of aligning and overlapping the first wafer and the second wafer based on the position of the second wafer.

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