JP5959138B2 - Semiconductor wafer handling equipment - Google Patents

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to the following US applications: US Provisional Application No. 60 / 779,684, filed March 5, 2006, United States Application, filed March 5, 2006 Provisional Application No. 60 / 779,707, U.S. Provisional Application No. 60 / 779,478, filed Mar. 5, 2006, U.S. Provisional Application No. 60 / 779,463, filed Mar. 5, 2006, filed Mar. 5, 2006 U.S. Provisional Application No. 60 / 779,609, U.S. Provisional Application No. 60 / 784,832 filed on March 21, 2006, U.S. Provisional Application No. 60 / 746,163, filed May 1, 2006, filed on July 12, 2006 US Provisional Application No. 60 / 807,189 and US Provisional Application No. 60 / 823,454 filed August 24, 2006.

  In semiconductor manufacturing, wafers and other substrates are transferred between various process chambers using robotic handlers. A permanent challenge in wafer handling is the need to find multiple wafers or a single wafer center with sufficient accuracy to allow accurate placement and processing within such a process chamber. Generally, a semiconductor manufacturing system uses various beam destruction sensor devices to detect a wafer edge by making a passing wafer a stripe. This data can then be used to find the center of the wafer relative to the robotic handler, thereby allowing more accurate control of subsequent movement and placement. Since center detection is important enough for fabrication, this process is always calibrated and repeated throughout the process for each wafer.

  Various physical sensors and processing algorithms have been devised to center the wafer in the semiconductor manufacturing process, but reduce the number of sensors required or improve the simplicity and / or accuracy of center detection calculations. There remains a need for improved wafer center detection techniques.

  This document discloses several wafer center detection methods and systems that improve upon existing technology used in semiconductor manufacturing.

  In one aspect, a method is provided for detecting a center of a wafer in an apparatus having an interior and a plurality of inlets, wherein the interior includes a robot arm, the apparatus includes a plurality of sensors, each of the sensors , Configured to detect the presence of a wafer at a predetermined location within the interior of the apparatus, the method removing a wafer from outside the interior through a first inlet of the plurality of inlets The wafer is pulled into the interior, the presence of the wafer is detected using a first sensor of the plurality of sensors, the robot arm is rotated, and the wafer is moved to the first of the plurality of inlets. Extending outside the interior through two inlets, detecting the absence of the wafer using the first sensor of the plurality of sensors, and sensor data from the plurality of sensors; Using the location data from the serial robot arm comprising the steps of, determining the center location of the wafer relative to the robot arm.

  The plurality of sensors may include an optical sensor. The plurality of sensors may include a light emitting diode. The plurality of sensors may include an autofocus photodiode detector. The location determination can include applying a Kalman filter to the position data from the robot arm. The method can include updating a Kalman filter based on the sensor data. The wafer can be substantially circular. The wafer may include an alignment notch. The plurality of sensors can include at least one detector disposed opposite the light emitting diode, such that an optical path from the light emitting diode to the photodetector includes a predetermined position within the interior. It is possible to The plurality of sensors may include at least one detector arranged to detect light from the light emitting diodes when reflected from the wafer at a predetermined location. The pulling-in step can include a pull-in operation in a linear motion. The stretching step may include a stretching operation in a linear motion. The rotation step may include rotation about a central axis of the robot arm.

  In another aspect, in a method disclosed herein for detecting a center of a wafer in an apparatus having one interior and a plurality of inlets, the interior includes a robot arm, and the apparatus includes a plurality of sensors. Each of the sensors is configured to detect the presence of a wafer at a predetermined location within the interior of the apparatus, and the method includes the interior of the interior via a first inlet of the plurality of inlets. The wafer is taken out from the outside, the wafer is drawn into the inside, the robot arm is rotated, the wafer is extended to the outside outside through the second inlet of the plurality of inlets, and the drawing is performed. Detecting the presence of a wafer at a predetermined location of at least one sensor during the rotation, stretching and stretching steps, thereby providing sensor data, the sensor data and the robot arm Using the location data from including the steps of, determining the center location of the wafer relative to the robot arm.

  The plurality of sensors may include an optical sensor. The plurality of sensors may include a light emitting diode. The plurality of sensors may include an autofocus photodiode detector. The location determination can include applying a Kalman filter to the position data from the robot arm. The method can include updating a Kalman filter based on the sensor data. The wafer can be substantially circular. The wafer may include an alignment notch. The plurality of sensors can include at least one detector disposed opposite the light emitting diode, such that an optical path from the light emitting diode to the photodetector includes a predetermined position within the interior. It is possible to The plurality of sensors may include at least one detector arranged to detect light from the light emitting diodes when reflected from the wafer at a predetermined location. The pulling-in step can include a pull-in operation in a linear motion. The stretching step may include a stretching operation in a linear motion. The rotation step may include rotation about a central axis of the robot arm. Detecting the presence of the wafer detects a first transition from absence to presence of the wafer in one of the plurality of sensors and presence of the wafer in the one of the plurality of sensors; Detecting a second transition from to non-existence, wherein the path of the wafer from the first transition to the second transition is non-linear. The path may include at least one arc that results from rotation of the wafer.

  In another aspect, an apparatus for manipulating a wafer disclosed herein includes an interior that can enter through a plurality of inlets, and a plurality of sensors disposed two at each of the plurality of inlets. Each sensor is capable of detecting the presence of a wafer at a predetermined location within the interior, and the plurality of sensors are such that at least two of the plurality of sensors are entirely within the interior. The wafer is arranged so as to be detected at any one of the wafer positions.

  The plurality of inlets can include four inlets. The plurality of inlets can include seven inlets. The plurality of inlets may include eight inlets. The plurality of sensors may include an optical sensor. The plurality of sensors may include at least one light emitting diode. The apparatus can include a robot arm having a central axis within the interior, the robot arm including an end effector for manipulating the wafer.

  In another aspect, an apparatus for manipulating a wafer disclosed herein includes an interior that can enter through a plurality of inlets, and a plurality of sensors disposed two at each of the plurality of inlets. Each sensor is capable of detecting the presence of a wafer at a predetermined location within the interior, and the plurality of sensors are arranged such that a first pair of sensors is connected to the plurality of inlets. Detecting a wafer linearly entering through each and a second pair of sensors located substantially immediately outside the maximum diameter of the wafer linearly entering through each of the plurality of inlets Each of the plurality of inlets shares one of the first pair of sensors and the second pair of sensors with each adjacent inlet of the plurality of inlets.

  The plurality of inlets can include four inlets. The plurality of inlets can include seven inlets. The plurality of inlets may include eight inlets. The plurality of sensors may include an optical sensor. The plurality of sensors may include at least one light emitting diode. The apparatus can include a robot arm having a central axis within the interior, the robot arm including an end effector for manipulating the wafer.

  In another aspect, the apparatus for manipulating a wafer disclosed herein each detects an interior that can enter through four inlets and the presence of a wafer at a predetermined location within the interior. And wherein the sensors are arranged into two square arrays centered on the interior center, the size of which is the first square array of the square arrays The array is smaller than the second square array, and the orientation is such that four sensors forming a group at opposite vertices of the two square arrays are located on the same straight line.

  The eight sensors can include optical sensors. The eight sensors may include at least one light emitting diode. The apparatus can include a robot arm having a central axis within the interior, the robot arm including an end effector for manipulating the wafer.

  In another aspect, an apparatus disclosed herein is a robot arm for manipulating a wafer, one providing encoder data identifying the position of one or more components of the robot arm. Or a robot arm including two or more encoders and a processor configured to apply an extended Kalman filter to the encoder data to estimate the position of the wafer.

  The location can include a wafer center and / or a wafer radius. The position can be determined in relation to an end effector of the robot arm. The position can be determined in relation to a central axis of the robot arm. The processor can recalculate the position each time new encoder data is received. The new encoder data can be received at about 2 kHz. The processor uses one or more of the Kalman filters using transition data from one or more sensors that detect the presence of a wafer at one or more predetermined locations within a robotic wafer handler. It is possible to configure to update the above equations.

  In another aspect, a method disclosed herein places a plurality of sensors within an interior of a wafer handling device, each of the plurality of sensors being the presence and absence of a wafer at a predetermined location within the interior. An encoder capable of detecting a transition between and operating a wafer using a robot arm, the robot arm identifying the position of one or more components of the robot arm Including one or more encoders that provide data and applying the encoder data to an extended Kalman filter to provide an estimated position of the wafer.

  The method detects a transition in one of the plurality of sensors to provide an actual position of the wafer, determines an error between the actual position and the estimated position, and based on the error, an extended Kalman filter It is possible to include the steps of updating one or more variables for. The application of the encoder data can include calculating the wafer position every 0.5 ms. The estimated position of the wafer can include the center of the wafer. The estimated position of the wafer can include the radius of the wafer.

  In another aspect, an apparatus disclosed herein is arranged to scan an interior chamber having a plurality of inlets shaped and sized to pass at least one wafer and a wafer within the interior. An internal robot including a contact image sensor and an end effector for manipulating the wafer, wherein the wafer is moved into a measurement volume of the contact image sensor, thereby obtaining an image of at least a portion of the wafer. A robot configured to acquire and a processor configured to process the image to determine the center of the wafer may be included.

  The robot can move the wafer linearly through the measurement volume of the contact image sensor. The orientation of the contact image sensor can be perpendicular to the path of the wafer. The contact image sensor may be oriented at an angle of 45 ° with respect to the wafer path. The robot can move the wafer along a curved path through the measurement volume of the contact image sensor. The robot can move the wafer in a non-continuous path through the measurement volume of the contact image sensor. The robot can rotate the wafer within the measurement volume of the contact image sensor. The robot can be configured to raise the wafer into the measurement volume of the contact image sensor. The robot can include a rotating chuck on an end effector configured to rotate the wafer. The rotary chuck can rotate 180 ° to 360 °. The apparatus can include a rotating chuck configured to raise the wafer from the end effector into the measurement volume of the contact image sensor. The length of the contact image sensor can be at least 300 mm. The contact image sensor may have a length that exceeds the diameter of the wafer. The contact image sensor can be disposed at one of the plurality of entrances into the interior. The apparatus can include a plurality of contact image sensors, each of the plurality of contact image sensors being disposed one at the plurality of entrances into the interior. The contact image sensor may be disposed so as to intersect the center of the interior. The apparatus may include a second contact image sensor, in which case the contact image sensor and the second contact image sensor are arranged on the same straight line. The contact image sensor and the second contact image sensor can be disposed at one of the plurality of entrances into the interior. The apparatus can include a plurality of pairs of collinear contact image sensors disposed at each of the plurality of entrances into the interior. The apparatus can include a second pair of collinear contact image sensors, wherein the second pair of collinear contact image sensors intersects the center of the interior. Placed in. The plurality of inlets can include four inlets. The plurality of inlets may include eight inlets. The processor can be further configured to identify alignment notches on the wafer. The processor can be further configured to determine a radius of the wafer.

  In another aspect, the method positions a contact image sensor to capture image data from within a robotic wafer handler, and obtains an image through at least a portion of the wafer by the contact image sensor, the image Each step of determining the center of the wafer based on Said step of passing at least a portion of the wafer by the contact image sensor may comprise passing the wafer linearly through the measurement volume of the contact image sensor.

  In another aspect, an apparatus disclosed herein includes a robot arm in a robot chamber, the robot arm including an end effector configured to manipulate a wafer, and a charge coupled device in the interior of the robot chamber. A linear array of charge coupled devices positioned to acquire image data from a measurement volume at one or more predetermined locations within the robot chamber.

  The apparatus can include an external illumination source that illuminates the linear array. The apparatus can include a wireless power coupling that inductively powers the linear array. The apparatus can include a wireless transceiver for wirelessly exchanging data with the linear array. The wireless transceiver can be located outside the robot chamber. The data may include the image data. The linear array may be a 1 × n charge coupled device array. The linear array can include a two-dimensional array of charge coupled devices. The apparatus may include a plurality of linear arrays that each capture image data at different locations within the interior. The robotic arm can include a chuck on the end effector configured to rotate a wafer within a measurement volume of the linear array. The robot arm can be configured to raise the wafer into the measurement volume of the linear array. The chuck can be rotated 180 ° to 360 °. The apparatus can include a rotating chuck configured to raise a wafer from the end effector into a measurement volume of the linear array. The apparatus can include a processor configured to determine the center of the wafer using the image data. The apparatus can include a processor configured to determine a radius of the wafer using the image data. The apparatus can include a processor configured to identify alignment notches on the wafer using the image data.

  In another aspect, an apparatus disclosed herein includes a robot arm in a robot chamber, the robot arm including an end effector configured to manipulate the wafer, and an edge from the wafer mounted on the end effector. And a linear array of charge coupled devices on the end effector positioned to capture the part data.

  The apparatus can include an external illumination source for illuminating the linear array. The apparatus can include a wireless power coupling that inductively powers the linear array. The apparatus can include a wireless transceiver for wirelessly exchanging data with the linear array. The wireless transceiver can be located outside the robot chamber. The linear array may be a 1 × n charge coupled device array. The linear array can include a two-dimensional array of charge coupled devices. The robotic arm can include a chuck on the end effector configured to rotate a wafer within a measurement volume of the linear array. The apparatus can include a rotating chuck configured to raise the wafer from the end effector and rotate the wafer within the measurement volume of the linear array. The apparatus can include a processor configured to determine the center of the wafer using the edge data. The apparatus can include a processor configured to determine the radius of the wafer using the edge data. The apparatus can include a plurality of linear arrays arranged to capture edge data from a plurality of locations on the surface of the end effector.

  These and other systems, methods, objects, features, and advantages of the present invention will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings.

  The detailed description of the invention and its specific embodiments presented below will be understood by reference to the drawings.

  The following description focuses on the detection of the center of a substantially circular semiconductor substrate having an alignment notch. However, it will be appreciated that suitable adaptations to many of the techniques described below can be made to detect the centers of other shapes such as ellipses, semicircles, squares, and rectangles. In addition, although semiconductor manufacturing is an important area for using the techniques described herein, the center detection techniques described below have broad applicability, such as extensive machine vision and It will be appreciated that it can be used in robotic applications.

  As used herein, the term “wafer” is a simplified representation of all substrates and other materials that can be manipulated by a semiconductor manufacturing system. The following description is applicable to wafers, and some illustrative embodiments refer specifically to wafers, but include semiconductor equipment including wafer manufacturing, wafer inspection, wafer cleaning, wafer calibration, and the like. Within it, it is possible to manipulate various other objects and other substrates including substrates having various shapes such as square or rectangular substrates (eg reticles, magnetic heads, flat panels, etc.) It will be understood that. All such workpieces are intended to be within the scope of the term “wafer” as used herein, unless a different meaning is explicitly provided or apparent from the context.

  FIG. 1 shows a plan view of a robotic operation module for transfer. In the module 110, a substantially circular wafer 120 can be manipulated by a robot (not shown) having a central axis 160, and a sensor detects the presence (or absence) of the wafer 120. In general, the module 110 may have a generally circular interior 170 having a radius sufficient to accommodate the rotational motion of the wafer and the robot between various entrances (not shown) to the module 110. Is possible. Additional space can be provided, and the shape can have any geometric shape that can accommodate the movement of the wafer, but the substantially circular shape can be the module 110 and other related features. This provides the great advantage of minimizing the volume in the vacuum environment maintained by the hardware.

  Also, in general, two or more of two or more formed in a shape and size to pass through the wafer 120 and any part of the robotic arm necessary to place and remove the wafer 120 outside the module 110. An inlet can be disposed in the module 110. In general, the size of each inlet will have a width and height to accommodate a single wafer and any other part of the robot end effector that must pass through the inlet during operation. This size can be optimized by having the robot move the wafer linearly through the center of each inlet, which advantageously saves valuable volume in a vacuum environment. Become. Semiconductor wafers are generally approximately circular as provided by industry standards. Such a wafer can also include an alignment notch to maintain alignment of the wafer in the rotational direction during the process, as described in more detail below, Further processing may be required during wafer center detection. On the other hand, more generally, the wafer can have various shapes and / or sizes. For example, 300 mm is the current standard wafer size, but the new standard for semiconductor manufacturing defines a wafer size exceeding 400 mm. In addition, some substrates can have other shapes, such as a rectangular substrate used in flat panels. Thus, the shape and size of components (and spaces) designed for wafer handling can vary, and those skilled in the art understand how to adapt components such as inlets to specific wafer dimensions. It will be understood that

  In one embodiment, the module 110 can include four inlets, one on each side of the module 110. The module 110 can also include different numbers of inlets, such as two or three. Furthermore, although a square module 110 is shown, the module 110 may have other shapes (such as commonly used in cluster processes) such as rectangular or hexagonal, heptagon, and regular polygons such as octagons. Is possible. A rectangular shape can have multiple entrances on one side, and a regular polygon can contain one entrance on each side. Thus, the square module 110 with one entrance on each side is a common configuration useful for semiconductor manufacturing, but many other shapes can be suitably adapted for use in manufacturing equipment. It will be appreciated that many other such shapes are intended to be within the scope of the present disclosure.

  As already mentioned, the sensor can include eight sensors 131-138 arranged as two square arrays 141, 142 centered on the central axis 160 of the robot. The sensors are such that four of the sensors 131-134 form a first inner array 142 and four of the sensors 135-138 form a second outer array 141. It is arranged. The layout of these sensors is best understood with reference to FIG. 1, but other features of the layout are described below. The two concentric square arrays 141, 142 are oriented so that their vertices form a sensor pair 150 of the inner array 142 and the outer array 141. The arrays 141, 142 are further rotationally oriented so that the four sensors at opposite vertices of the two square arrays 141, 142 are co-linear and form a straight line that intersects the center of the interior 170 or the central axis 160 of the robot. The direction is set. This last limitation is not strictly necessary, i.e. the robot can have more than one axis, and the robot does not require an axis at the center of the interior 170 for various rotations. It is possible to adapt to exercise. However, it is a traditional and realistic layout for a robotic handler that provides 360 ° freedom of movement. Also, as the wafer 120 first enters (or exits) the interior 170 from one of a plurality of inlets generally located at the center of each side, the two sensors of the inner array 142 may detect the wafer. It will be appreciated that the two sensors of the outer array 141 are located on both sides just outside the diameter of the wafer 120. Thus, while maintaining the ratio of only two sensors for each inlet, at least two sensors always detect the wafer 120 while the wafer 120 is within the interior 170, and at least one sensor is internal. It can be ensured that any rotational movement of the wafer 120 in 170 will be detected immediately. As a major advantage, this configuration also allows for wafers in the interior, for example, when module 110 and sensors 131-138 are powered up after a power failure (no a priori data on wafer position). Ensure that the presence can always be detected.

Similar configurations can be provided for modules having 5, 6, 7, 8, or more inlets. In general, each inlet, it is possible to have two sensors, in this case, the first sensor is arranged to detect the wafer when the wafer has been fully moved from the inlet into the interior, first Two sensors are placed just outside the diameter of the wafer. In such embodiments, each pair of inner and outer array sensors can be shared with adjacent inlets, i.e., immediately adjacent inlets on either side thereof.

  Although FIG. 1 shows a particular configuration of sensors 131-138, other criteria can be used to determine the appropriate number and placement of sensors. For example, sensor placement can advantageously provide at least four points around the wafer during any movement sequence when the wafer is removed from the station and placed in another station. Any group of three points used to estimate the center and radius usefully includes an angle greater than 60 ° between the at least three points, and to define the center and radius It is possible to usefully include an angle of less than 180 ° between any three points used (ie there should be no lack of points defining its edges in the 160 ° area) Is). Additional points can be advantageously used to improve estimation via direct calculation or to validate the calculation circle. The sensor can be advantageously arranged within the rocking radius of the link of the robot arm, with a reference mark that can reliably and repeatedly trigger the sensor.

  The configuration of the sensor can also be adapted to a particular end effector. For example, a fork-type end effector supports the wafer around the side edges but not the front. With conventional wafer sizes, this leaves a 250 mm wide area in the middle of the fork, but the side edges cannot be used for detection. In the case of a paddle type end effector, the center 150 mm across the center line of the linear extension is vacant for sensor placement, but the rear end of the wafer toward the robot arm's wrist is the end effector. Can be completely blocked from the sensor.

  Sensors 131-138 generally operate to detect the presence of a wafer at a predetermined location within interior 170. As used herein, it will be appreciated that detection of presence includes detection of absence as well as detection of transitions between the absence and presence of a wafer. This type of detection involves the use of an optical sensor such as a reflection technique in which light is reflected towards the light source when a wafer is present or a beam blocking technique in which the beam is blocked between the light source and the sensor when a wafer is present. Many techniques can be used as appropriate. In one embodiment, the sensors 131-138 use light emitting diodes or laser light sources, and light is sent to an autofocus photodiode detector (which facilitates alignment during installation). The sensor described above is one of the cost-effective solutions for detecting the presence of a wafer at a given location, but other sensing techniques are similar as long as they can be adapted to a vacuum semiconductor environment. It will be understood that it can be used for: This can include, for example, sonar, radar, or other electromagnetic or distance or position sensing techniques.

  The distance between the inner array 142 and the outer array 141, or the distance between each sensor pair 150, will generally depend on the size of the wafer operated by the system. In one embodiment, the position of the sensor can be adjustable to form a larger or smaller array while maintaining the linear and diagonal relationships described above. In this way, the module 110 can be easily adapted to different sized wafers.

  During normal operation, the sensors 131-138 use a circular model, a linear model (such as the Kalman filter technique described below), or any other suitable mathematical technique, neural network technique, heuristic technique, or other technique. Used to determine the location of the center of the wafer 120. Here, a method for detecting the position and center of the wafer will be described in more detail. In general, the techniques shown below use a combination of data from sensors 131-138 and data from encoders for one or more robotic handlers that provide data regarding the position of robotic components. . The following discussion focuses on sensor and encoder data, but times such as those detected by any clock or signal in the system should also be used explicitly or implicitly in wafer center detection calculations. It will be understood that this is possible.

  FIG. 2 shows a plan view of a wafer handling module having four sensors for detecting the position of the wafer. In this embodiment, the system 200 can use only one sensor 202 at each inlet. The sensor 202 can be any sensor described above. In this case, the sensor 202 is preferably within the diameter of the wafer 204 near each inlet so that at least one edge detection can be obtained as the wafer passes through any of the inlets. Be placed. As described above, the wafer handling module 210 is substantially square and includes four inlets, each inlet having one sensor 202.

  FIG. 3 shows a generalized process for wafer center detection.

  In general, a robot arm (such as any of the robot arms described above) can perform a number of operations to transfer a wafer (such as any of the above-described wafers) from one location to another in the semiconductor manufacturing process. It is. This involves removing the wafer from the first location as shown in step 302, pulling the robot arm into a module (such as any of the modules described above) as shown in step 304, and moving the robot arm as shown in step 306. Rotating toward the other entrance of the module, extending the robot arm through the entrance as shown in step 308, and placing the wafer in a second location as shown in step 310. Includes numerous operations. The first and second locations are modules for other robotic handlers, load locks, buffers or transition stations, all kinds of process modules, and / or other additional processes (cleaning, measuring, scanning, etc.) Can be anywhere within the manufacturing facility. As shown in FIG. 3, this process can be repeated without limitation as the wafer is moved into and out of the facility and processed by various process modules. Although not explicitly shown, other steps (such as opening and closing isolation valves to enter the interior or waiting inside to access various resources) are performed by the system during these operations. It will be understood that this is possible. The details of the various robot operating operations are well known in the art, and any such robot arm or operating function can be suitably used with the process shown in FIG. This includes various combinations of robot arm stretching, retraction, and rotation, z-axis motion by the robot arm, and any other operation that can be effectively used in wafer operations.

  While the robot arm is controlled by the wafer operation as shown in step 302, the encoder directly receives the data related to the position of the robot arm or the position of the drive element (the direction of the rotation direction) that controls the operation of the robot arm. Provided by detecting). This data can be received for a process as shown in step 302. As shown in step 330, the sensor data may include one or more sensors (described above) that detect the presence, absence, or transition between presence and absence of a wafer at a predetermined location within the robotic handler. Or any other sensor). Physical data relating to such detection can come in a variety of forms, including the presence of an optical signal, the absence of an optical signal, the intensity of an optical signal, or a binary signal that encodes any of the above. Will be understood. All such signals can be effectively used to detect the absence, presence, and transition as described herein.

  As shown in step 330, the encoder data and sensor data can be used to calculate position data about the wafer (alignment, wafer center, etc.). Details of various algorithms for calculating the wafer position will now be described. Although not explicitly shown, it is understood that a controller or other device that calculates the wafer position can apply this data in any of a variety of ways to control further movement of the robot arm. Like. In particular, this data can be used for accurate placement at the destination location. The data can also be stored and used as an initial estimate of the wafer position when the same wafer is removed for further motion.

  In the embodiment of FIG. 2 having four inlets and four sensors, the wafer edge data (obtained during the transition at step 330) is used to determine the center of the wafer relative to the transfer path, and thus from its detection location. The wafer can be easily moved to the destination position. The sensor position, robot position, and destination location (such as in a process chamber or load lock) are defined in a global coordinate system, which is relative to the above other elements in a wafer processing system including a robotic module for wafer handling. It is easy to determine the correct position. The world coordinate system can be advantageously defined in relation to the sensor position.

  Through training, the controller can associate sensor position or encoder data to the world coordinate system, using sensor data, for example, to detect robot end effector features and recording simultaneous values from the encoder. . In this way, the controller can map the encoder values to the world coordinate system, so that when the robot moves, the position of the world coordinate system of the robot can be known. The controller can similarly determine the world coordinates of other elements (such as destinations) in the wafer processing system and create a world coordinate map of the elements of the wafer processing system. The association of the robot position with the world coordinate system can additionally or alternatively be done manually using a scaled instrument or a measuring tool supported by the robot. The above is for illustrative purposes only, and many techniques for associating robot positions to the world coordinate system are known in the art and can be used effectively in the systems described herein. Will be understood. For example, a sensor-based world coordinate system is one possible approach, but it is possible to perform a similar center detection function using an end effector-based world coordinate system.

  After the robot arm has been properly trained, sensor data can be acquired while the wafer is being manipulated via a pull / rotate / stretch movement, as shown in FIG. If the wafer moves in a non-linear path across multiple sensors having a predetermined location, it is possible to determine the wafer position using multiple techniques as appropriate. Some of these techniques are described in detail below for purposes of illustration and not limitation.

  To estimate the center and radius of the wafer, the edge point data in world coordinates can be applied to the equation of the circles that exist simultaneously. For example, as described in Linear Algebra and its Applications by Gilbert Strang (Academic Press, Inc. 1980), the equations are converted to matrix form and the so-called pseudoinverse is used to compute the least squares solution for the matrix. Can be provided. This solution minimizes the square error between the circumference and the detected edge points. From this solution, the center position and radius can be calculated. Mathematically speaking, the general formula of a circle can be expressed as follows:

(X−x _c ) ² + (y−y _c ) ² = r ²
This can be rewritten as follows.

x ² + y ² + Dx + Ey + F = 0
here,
D≡−2x _c , E≡− ² y _c , F≡x _c ² + y _c ² −r ²
Given n points from the circumference, a matrix of n equations can be created as follows:

Ax = b
When there are three points, the matrix A is a square matrix, and its solution can be expressed as follows by inverting the matrix A.

x = A ⁻¹ b
If more than four points are available, pseudo-inverse can be used to provide a least squares solution to the problem as described above. This can be expressed as:

x = (A ^T A) ⁻¹ A ^T b
This solution will minimize the square error between the circumference and all points. From the solution for the vector x, the center position and estimated radius for a circular wafer can be calculated from D, E, F.

  In the case of notch detection, it is possible to determine the distance of each detected point from the calculated center and remove any points that do not fit the desired circle (using any suitable criteria). The center and radius can then be recalculated. Thus, alignment notches are detected in these calculations by identifying detected edge points that deviate from the calculated circle by exceeding some predetermined threshold or tolerance. Is possible. These points can be removed for center detection. General information about the wafer shape can also be used to detect (and exclude from further calculations) points that may be related to robotic components rather than the wafer. In one aspect, the system includes a singularity that is close to the expected circumference (which may be due to the alignment notch) and a singularity that is far from the expected circumference. It is possible to distinguish them, and it is possible to restore the alignment in the rotation direction of the wafer. In general, such a distinction is the general notion that the alignment notch is characterized by the relative magnitude of the variation, as well as the absence of an unexpected wafer while the robot arm will generally cause the presence of an unexpected wafer. It can be based on

  In addition, various events in motion, such as radial displacement, linear displacement, or other simple or complex motion of the wafer relative to the end effector, are detected and clarified and used in techniques known to those skilled in the art. Is possible.

  A number of functions related to wafer detection can be usefully performed. For example, the system designed in this document calculates the robot arm link offset, calibrates the sensor location, calibrates the beam width for the optical sensor, calculates the wafer center position relative to the end effector, Detect the presence of wafers at the location, determine when the slot valve door is open or shut off, and accurate wafers in process modules, load locks, and other connected modules in the manufacturing facility An arrangement can be provided. An example of a plurality of related processes will be described below.

  The robotic handlers and sensors can be operated to determine the location of the wafer using the above techniques as well as other suitable center detection techniques. In one embodiment, the system tracks sensor data during pull-in (step 304) and rotation (step 306) and begins calculating the wafer center at the start of stretching (step 308). In this embodiment, after the rotation, the processor calculates the instantaneous radius and wafer center angle (eg, using the least squares described above) and an appropriate global coordinate system (eg, end effector, module, etc.). It is possible to calculate the sensor position by, for example, conversion to. It is possible to detect and remove singularities by comparing this estimated radius with the expected value. An error vector can then be derived from measurements for subsequent sensor transitions and applied to correct the expected trajectory of the wafer. Thus, in one aspect, the robotic handler can collect sensor data during retraction and rotation, and collect additional sensor data during stretching and calculate the wafer position.

  Other techniques can be used for the center detection calculation. In one embodiment, using encoder updates in real time (eg, at 2 kHz, every 0.5 ms, every 50 ms, or other suitable frequency or time increments) with time data about each sensor transition event. It is possible to use a Kalman filter.

  FIG. 4 shows a wafer center detection method using a Kalman filter. In general, the calculation of the wafer position as shown in step 330 can be performed using a Kalman filter that applies encoder data to determine wafer position and / or predict sensor transitions. . However, as a modification of the general method shown in FIG. 3, the Kalman model (for center detection) can be periodically updated. More specifically, as shown in step 330, sensor data is received at each transition of the sensor, including the time of the transition (and the sensor identifier and / or location, if necessary). Based on this data, it is possible to calculate the error between the expected transition time at the location and the measured transition time, as shown in step 410. Then, as shown in step 420, the Kalman filter can be updated with this error data to make subsequent estimations more accurate. Thus, in general, the encoder data can be used to provide wafer center data for control of the robot arm and the center detection model (e.g., extended Kalman filter equation) can be updated using the actual detected transitions. Is possible.

For example, the wafer is placed in a particular position (Xe, Ye), and velocity and acceleration V is estimated, when moving in a can, the model predicts a sensor is triggered at time t _e, this system, it is possible to identify the actual transition at time t _s. The encoder position measured at time t _s (or optionally its time stamp) can produce an error represented by:

  The extended Kalman filter equation can then be used as described, for example, in Applied Optimal Estimation by Arthur Gelb (MIT Press 1974). The application of the equations described in Gelb applies to the system model:

And measurement model:

Can be described briefly.
Here, the state estimation propagation is

And the error covariance propagation is

It is.

  As a major advantage, this generalized technique allows the use of individual sensor events incrementally without requiring multiple (eg, three) points to identify a circular wafer. Although the specific order of each step is suggested by FIG. 4, the operations shown there are repeatedly performed during the operation of the robotic wafer handler, inferring the specific order or timing of each step. It will be understood that it should not. Nevertheless, it is generally true that in some embodiments, the encoder data is continuously provided in real time, while the transition that initiates the model update will occur intermittently as the wafer is moved by the robot. It becomes. It is also understood that the extended Kalman filter is one useful technique for converting encoder data into wafer center information, but other filters or linear modeling techniques can be applied as well. Like.

  The methods and systems described above are generally applicable to wafer center detection using wafer detection at discrete locations. It is also possible to use a plurality of linear sensors such as a charge coupled device or a linear array of contact image sensors to capture wafer data in a plurality of linear segments. Several devices using linear sensors are described below. In these techniques, center detection can generally be achieved through direct analysis of image data rather than inference derived from multiple discrete sensor events as in the techniques described above.

  FIG. 5 shows an apparatus having a linear image sensor for capturing image data from a passing wafer. The apparatus 500 can include a top surface 502, a bottom surface 504, an interior 506, a linear image sensor 508, a light source 510, and a wafer 512.

  The device 500 can be any device used in a semiconductor manufacturing process, such as, for example, load locks, buffers, aligners, and robotic handlers. In one embodiment, the apparatus 500 is a robotic handler that includes a robot arm (not shown) having an end effector for manipulating the wafer.

  The top surface 502 and the bottom surface 504 can partially surround the interior 506. Although not shown, the apparatus 500 may also have a side that may include, for example, a plurality of inlets for passing a wafer as well as a slot valve or other isolation mechanism for isolating the interior 506 of the apparatus 500. It will be understood that this is possible. In general, the shape and size of the various surfaces of apparatus 500 are not critical, but at least one of the surfaces is parallel to the plane of motion of the wafer and an image sensor is placed on the surface to provide an internal 506. It should be possible to capture image data from a wafer moving through it.

  A linear image sensor 508 can be placed on the top surface 502 of the device 500 as shown or on the bottom surface of the device. In one embodiment, the linear image sensor 508 can be a contact image sensor. Commercially available contact image sensors typically include a linear array of a plurality of detectors (such as charge coupled devices) having an integrated focusing lens and a light source 510 (such as LEDs located laterally parallel to the linear sensor array). . Conventional contact image sensors use red, green, and blue LEDs or similar broad spectrum light sources, but the wafer uses only a single color light source (eg, red LED) for center detection. It is possible to image appropriately. In general, the contact image sensor can be disposed close to an object to be operated. In another embodiment, linear image sensor 508 includes a linear array of charge coupled device (“CCD” or complementary metal oxide semiconductor “CMOS”) photosensors. The linear array can be a 1 × n array, 2 × n array, or other suitable number that includes n sensors (eg, 128 sensors, or other suitable number of sensors that span part or all of a wafer). It can be a one-dimensional or two-dimensional array. In general, CCD or CMOS devices can be placed farther from the object being imaged than current CIS devices and can provide higher resolution. However, they require additional external light for good image capture quality. CIS devices, on the other hand, are readily available in lengths that exceed the diameter of common semiconductor wafers, provide an inexpensive alternative for image capture, and pre-packaged arrays Provides high accuracy. Both technologies are suitable for use in the embodiments described herein, with appropriate adaptations for the application, each providing the advantage of being more suitable for a particular application. Become. Some of these variations are described below, but as noted, any of these techniques or other optical techniques are effectively used as the term “linear image sensor 508” as used herein. It is possible. The linear image sensor 508 has a fixed field of view or measurement volume that allows image data to be captured. In general, a linear image sensor 508 can have an effective measurement volume that depends on a number of factors, such as ambient light, the desired accuracy of the image, lenses and other optics associated with the sensor, and the like.

  Wafer 512 can pass through apparatus 500 in a linear path as indicated by arrow 514. It will be appreciated that a linear path is one possible wafer movement, but many other movements can be provided by the robotic handler. For example, the wafer can move in a curved path with a rotational movement of the robot, or can move in a non-continuous path consisting of a plurality of different linear and / or curved paths. As described further below, the wafer may additionally or alternatively rotate about its axis. The data obtained from such a scan is generally directly analyzed to determine the wafer center and other wafer position data (eg, rotation direction, radius, etc.). It will be appreciated that for correct interpretation, it should be combined with robot motion, for example using encoder data or other sensor data.

  FIG. 6 shows a plan view of a contact image sensor used for wafer center detection using linear wafer motion. Within a device that can be any of the devices 500 described above, a single CIS 608 positioned perpendicular to the direction of motion 606 moves the wafer 602 with the alignment notch 604 linearly (arrow 606). It is possible to pass by. In one embodiment, the CIS 608 can include a single module having a length of 310 mm and complete wafer detection (notch / position) as the wafer moves through the inlet into and out of the device. It can be placed across the entrance to the device to provide alignment detection). This type of wafer detection can actually provide a photocopy of the wafer 602, from which alignment and dimensions can be obtained directly by image analysis. As a major advantage, this configuration provides a complete wafer scan without the need for additional robot arm movement or the like. For this reason, the throughput of the transfer device can be processed at a speed limited only by the robot and other constraints. In other embodiments, one such CIS 608 may be placed at each of the plurality of entrances (eg, at the four entrances of a square robotic handler). A single CIS 608 can additionally or alternatively be placed across the center of the device. Using a CIS608 of approximately 450 mm, a single CIS can be positioned at a 45 ° angle to all four inlets, which captures all linear wafer motion through the device. Cross the center of the device as possible. This configuration does not capture all wafer size data for every movement through the apparatus, but nevertheless provides sufficient data for wafer center detection for every possible movement, A robotic handler can provide additional motion to ensure that the entire wafer surface is scanned.

  FIG. 7 shows a plan view of a contact image sensor used for wafer center detection using curvilinear wafer motion. Within an apparatus that can be any of the apparatus 500 described above, a single CIS 708 can pass through a wafer 702 having an alignment notch 704 in a curved motion (indicated by arrow 706). . This configuration is suitable for positioning at various locations within a robotic handler where the robotic arm employs rotation, but typically the resulting image data is processed to capture the wafer 702. It will be appreciated that the non-linear path 706 will be offset. .

FIG. 8 shows a plan view of a contact image sensor used for wafer center detection using rotating wafer motion. Within an apparatus that can be any of the above-described apparatus 500, a wafer 802 having an alignment notch 804 can be rotated as shown by arrow 810 about an axis located approximately at the center of CIS 808. Is possible. Within this device, the robotic handler may include a z-axis control and rotation chuck. The robotic handler can position the wafer 802 at the center below the CIS 808 and then optionally raise the wafer 802 closer to the CIS 808 for more accurate image acquisition. The wafer can then be rotated 180 ° (or more) to obtain a complete image of the wafer 802 including the alignment notch 804. The CIS 808 can be positioned at the center within the device (such as the central axis inside the device, the central axis of the robot arm inside the device, or the home position of some other robot within the device). This configuration advantageously provides complete scanning with a half rotation of the rotating chuck, which can simplify the chuck design and reduce scan time. As another advantage, this configuration can provide a full wafer scan regardless of wafer size (within the limitations imposed by the length of CIS 808). Thus, a single system can provide complete edge detection for various shapes and sizes.

  FIG. 9 shows a pair of linear CCD arrays used for wafer center detection using linear wafer motion, which is placed at the entrance to a device such as any of the devices 500 described above, for example. Is possible. In this embodiment, the first linear array 902 and the second linear array 904 of CCDs can be disposed across a portion of the linear path 906 of the wafer 908. The arrays 902, 904 can be positioned along the outer edge of the entrance to an apparatus, such as a robotic handler, for example, so that image data is captured each time a wafer passes through the entrance. Similarly, additional sensor array pairs can be placed at one or more additional inlets to the device. This configuration takes advantage of commercially available short linear CCD arrays that are readily available, but may not be able to capture the alignment notches used to determine the orientation of the wafer 908 in the rotational direction. It is also a sexual thing.

  FIG. 10 shows a single CCD array used for wafer center detection using rotating wafer motion. In this embodiment, a single linear CCD array 1002 can be placed on the lid or other suitable internal surface of a device such as a robotic handler or any of the other devices 500 described above. After the wafer 1004 is properly positioned below the array 1002, the wafer 1004 is subjected to full rotation as indicated by arrow 1006 to capture all edge data of the wafer 1004 including the position of the alignment notch 1008. It becomes possible. This embodiment can use, for example, the robotic handler and rotary chuck with z-axis motion described above. However, in this embodiment, the rotating chuck is preferably rotated at least 360 ° to ensure complete capture of edge data. In another embodiment, two collinear arrays at opposite edges of the wafer 1004 can be used to obtain a full edge scan in half a turn.

  FIG. 11 shows four CCD arrays used for wafer center detection using complex wafer motion. As previously described, any of the above-described apparatus 500, etc., may be arranged as two collinear intersecting lines to navigate the wafer path in a manner substantially similar to that described above with reference to FIG. It is possible to include four CCD arrays 1102 to cover. Wafer 1104 can traverse the interior of the apparatus along a path 1106 that includes linear and curvilinear motion. In one embodiment, the wafer 1104 can be retracted sufficiently toward the center to ensure detection of the alignment notch 1108 at any point during the combined movement of the wafer 1104.

  FIG. 12 shows a plan view of the CCD sensor on the end effector of the robot arm. The wafer handling robot arm 1200 may include a plurality of links 1202 and end effectors 1204. The end effector 1204 can include a plurality of linear CCD arrays 1206 arranged, for example, to identify the four edge positions of the wafer 1208 disposed thereon. As a major advantage, this configuration places the wafer 1208 very close to the linear CCD array 1207, which provides very high image accuracy. Furthermore, this design does not require any z-axis or rotational movement by the end effector 1204. However, as is apparent from FIG. 12, this configuration also may not be able to identify alignment notches for many rotational orientations of the wafer 1208.

  FIG. 13 shows a perspective view of a single CCD sensor on an end effector 1204 having a rotating chuck. In this embodiment, a single linear CCD array 1302 can be mounted on the end effector 1304 at a location that obtains edge data from a wafer 1306 that is positioned approximately in the center of the end effector 1304. The end effector also includes a single-axis rotating chuck that rotates the wafer 1306 once to obtain complete edge data from the wafer 1306 (including detection of alignment notches (if the notches are present)). It is possible.

  Multiple external devices 1320 can support the use of a CCD array 1302. For example, an external light source can be placed in the apparatus to illuminate the CCD array 1302 while the end effector 1304 is in a particular position. As another example, a power supply that is inductively coupled to the CCD array 1302 can be provided to wirelessly power the CCD array 1302 in a vacuum environment. As another example, image data can be received wirelessly from a CCD using a radio frequency or other wireless transceiver. In such wireless configurations, transceivers and power couplings, etc. can be placed away from the CCD array (eg, at the central axis of the robot arm or some other location near the corresponding wireless system).

  FIG. 14 shows a single CCD sensor in a robotic operating module. In this embodiment, a single linear CCD array 1402 and any associated light source or other light emitting means can be mounted on the inner wall of a device such as a robotic handler or any of the other devices 500 described above. . In operation, the end effector 1404 can position the wafer 1406 so that the wafer 1406 is positioned at the center of the rotating chuck 1408 (separate from the end effector 1404) and its edge is on the CCD array 1402. It is. The end effector 1404 can then provide z-axis motion as indicated by arrow 1410 to lower the wafer 1406 onto the chuck 1408. The chuck 1408 can then rotate the wafer 1406 one complete revolution to provide a scan of the entire periphery of the wafer. In addition to capturing position data for the wafer 1406, this approach detects the alignment notch on the wafer 1406 (if the notch is present) to determine the orientation of the wafer 1406 in the rotational direction. To capture. As in the embodiment of FIG. 13, a device 1420, such as a light source, wireless power combiner, or wireless data transceiver, is located within the interior or at a suitable location outside the module and is described herein. It is possible to enhance the operation of the wafer center detection system.

  The above-described embodiments include sensors in devices such as load locks, robotic handlers, or transfer stations (or on end effectors in certain embodiments), although the techniques are located elsewhere in the manufacturing system. It will be understood that it is possible. For example, any of the above techniques can be suitably adapted for use as an aligner. Similarly, many of the above techniques can be suitably adapted for use as a measurement station in other devices such as robot handlers or transfer stations. In such embodiments, by providing space for a measurement station that does not interfere with other entrance or exit paths from the robotic handler, or by taking measurements at locations displaced on the z-axis from other robotic activities. The robot can perform other wafer movements as the measurement station scans the wafer.

  It will be appreciated that the method described herein can be implemented in hardware, software, and any combination thereof suitable for monitoring or controlling a semiconductor manufacturing robotic system. Each process includes one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other (one or more) programmable devices, and internal and / or Or it can be implemented in an external memory. The process may additionally or alternatively be an application specific integrated circuit, programmable gate array, programmable array logic, or any other device or devices that can be configured to process electrical signals. It is possible to implement with the combination of. One or more processes may be executed in a structured programming language such as C, an object oriented language such as C ++, or the like, compiled or interpreted in one of the above devices. Code that can be executed by a computer written using any high-level or low-level programming language (including database programming languages and technologies), and different types of processors, processor architectures, or combinations of various hardware and software It will be further understood that it can be implemented as a combination. All such variations are intended to be included within the scope of this disclosure.

  While the invention has been described in terms of certain preferred embodiments, other embodiments will be apparent to those of ordinary skill in the art and such other embodiments are also included herein.

FIG. 6 shows a plan view of a wafer handling module with eight sensors for detecting the position of the wafer. FIG. 2 shows a plan view of a wafer handling module with four sensors for detecting the position of the wafer. Figure 2 shows a generalized process for wafer center detection. 3 shows a wafer center detection process using a Kalman filter. 1 shows an apparatus having a linear image sensor. FIG. 2 shows a plan view of a contact image sensor used for wafer center detection using linear wafer motion. FIG. 2 shows a plan view of a contact image sensor used for wafer center detection using curvilinear wafer motion. FIG. 3 shows a plan view of a contact image sensor used for wafer center detection using rotating wafer motion. Figure 2 shows a pair of linear CCD arrays used for wafer center detection using linear wafer motion. Figure 2 shows a single CCD array used for wafer center detection using rotating wafer motion. 4 shows four CCD arrays used for wafer center detection using complex wafer motion. Fig. 2 shows a CCD sensor on an end effector of a robot arm. Fig. 4 shows a single CCD sensor on an end effector with a rotating chuck. A single CCD in a robotic operation module is shown.

Claims (8)

A semiconductor wafer operating device,
A robotic operation module for transfer including one interior, one transfer robot, and a plurality of inlets, the transfer robot having one rotation axis and configured to transfer a semiconductor wafer A robotic operation module for transfer, and
A plurality of sensors, each of which detects the presence of a semiconductor wafer at a predetermined location within the interior during movement of the transfer robot including at least one rotation about the rotation axis of the transfer robot. It has a plurality of sensors that can be detected,
The plurality of sensors are
Two of the plurality of sensors are disposed at each of the inlets, and the plurality of sensors are located within the interior of the semiconductor wafer during movement of the semiconductor wafer by the transfer robot. at least two sensors to detect the semiconductor wafer, which is disposed on the transfer robot, is disposed with respect to the transfer robot and the internal for each position, and,
As the said sensor disposed in each of at least the inlet is different from other sensors, immediately detects the rotational movement of said semiconductor wafer around the rotation shaft of the transfer robot, the semiconductor wafer is a Arranged so as to be disposed outside the semiconductor wafer at an interval longer than the diameter of the semiconductor wafer when completely passing through the inside through one of a plurality of inlets. A semiconductor wafer handling device.   Two sensors are disposed adjacent to each of the plurality of entrances into the interior of the robotic manipulation module, and the semiconductor wafer handling device is based on encoder data from one or more robots The semiconductor wafer handling device according to claim 1, further comprising a second system including a processor configured to apply estimation of a wafer position by an extended Kalman filter to the determination of the center position of the semiconductor wafer.   The semiconductor wafer manipulating apparatus according to claim 1, comprising four, seven, or eight inlets. A semiconductor wafer manipulating apparatus for manipulating a substantially circular wafer,
One interior accessible via multiple entrances;
A plurality of sensors, each sensor comprising a plurality of sensors capable of detecting the presence of a substantially circular wafer at a predetermined location within the interior;
The plurality of sensors are
Two of the plurality of sensors are disposed at each of the inlets, and the plurality of sensors are circular within the interior of the circular wafer during movement of the circular wafer by the transfer robot. And at least two sensors for each position of the wafer are positioned relative to the transfer robot and the interior so as to detect the circular wafer positioned on the transfer robot; and
At least another sensor different from the sensor disposed at each of the inlets is the circular wafer centered on the central axis of the transfer robot when the transfer robot is located in the interior. Arranged to be outside the diameter of the circular wafer so as to immediately detect the rotational movement of
The sensor disposed at each of the inlets is arranged to detect the circular wafer when the circular wafer has completely passed through the interior through the respective inlet. The other sensor that immediately detects the rotational movement of the wafer is just outside the diameter of the circular wafer when the circular wafer has completely passed into the interior through one of the plurality of inlets. Located in the
Semiconductor wafer handling device.   The semiconductor wafer manipulating apparatus according to claim 4, comprising four, seven, or eight inlets.   The semiconductor wafer manipulating apparatus according to claim 4, wherein the plurality of sensors include optical sensors.   The semiconductor wafer handling device according to claim 6, wherein the plurality of sensors include at least one light emitting diode.   5. The semiconductor wafer manipulating apparatus according to claim 4, wherein the transfer robot includes a robot arm having the central axis in the interior, and the robot arm includes an end effector for manipulating the circular wafer.

Images