KR101570626B1 - Wafer Center Finding - Google Patents

Abstract

A plurality of wafer center search methods and systems are disclosed that enhance current technology used in semiconductor manufacturing processes.

Description

{Wafer Center Finding}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wafer alignment in semiconductor processes, and more particularly to a center search method for wafers.

During semiconductor manufacturing, wafers and other substrates are transferred between the various process chambers using a robot handler. One of the ongoing challenges of wafer handling is the need to position the wafer or wafer center with sufficient accuracy for accurate placement and processing within the process chamber. Generally, a semiconductor manufacturing system uses various beam-breaking sensor devices to "stripe" a moving wafer and detect the wafer image. This data can in turn be used to position the wafer center relative to the robot handler, whereby subsequent movement and placement can be controlled more precisely. Center findidng is very important for manufacturing processes where this process is routinely adjusted and repeated through the process of each wafer.

While many physical sensors and process algorithms have been devised to center the wafer in semiconductor manufacturing processes, there remains a need for improved centering techniques that reduce the number of sensors required, simplify center search operations, or improve accuracy .

A number of wafer center search methods and systems are disclosed that can enhance existing technologies used in semiconductor manufacturing processes.

In one aspect, a method is provided for searching a center of a wafer in an apparatus having an internal structure and a plurality of inlets. Wherein the internal structure includes a robot arm and the apparatus includes a plurality of sensors each of which is adapted to detect the presence or absence of a wafer at a predetermined location in an internal structure of the apparatus, The retrieving method comprising: retrieving the wafer out of the endurance structure through a first one of the plurality of inlets; Inserting the wafer into the internal structure and detecting presence or absence of the wafer using a first sensor among the plurality of sensors; Rotating the robot arm; Moving a wafer out of the internal structure through a second one of the plurality of inlets and detecting a member of the wafer using a first one of the plurality of sensors; And determining the position of the center of the wafer relative to the robot arm using sensor data from the plurality of sensors and position data from the robot arm.

The plurality of sensors include an optical sensor. The plurality of sensors include light emitting diodes. The plurality of sensors include autofocus photodiode detectors. The step of determining the position of the center of the wafer includes applying position data from the robot arm to a Kalman filter. The method may further comprise updating the Kalman filter based on the sensor data. The wafer is substantially circular. The wafer includes an alignment notch. The plurality of sensors include one or more detectors positioned to face the light emitting diodes so that the path of light from the light emitting diode to the detector includes a predetermined location within the interior structure. The plurality of sensors include one or more detectors, wherein when the detectors are reflected from a wafer in a pre-designated position, light from the light emitting diodes is arranged to be detected by the detector. The operation of inserting the wafer includes an operation of linearly moving and inserting. The operation of moving the wafer includes an operation of linearly moving the wafer. The step of rotating the robot arm includes the step of rotating about the central axis of the robot arm.

In another aspect, a method of detecting a center of a wafer in an apparatus that includes an internal structure and a plurality of inlets is published. Wherein the internal structure includes a robot arm, the apparatus includes a plurality of sensors, each of the plurality of sensors detects presence or absence of a wafer at a predetermined location in an internal structure of the apparatus, The method includes: withdrawing the wafer out of the internal structure through a first one of the plurality of inlets; Inserting the wafer into the internal structure; Rotating the robot arm; Moving the wafer through the second of the plurality of inlets out of the interior structure; Providing sensor data by detecting the presence or absence of the wafer at a pre-designated location of the at least one sensor during the inserting, rotating and moving; And using the sensor data and position data from the robot arm to determine a position of the center of the wafer relative to the robot arm.

The plurality of sensors includes an optical sensor. The plurality of sensors include light emitting diodes. The plurality of sensors include autofocus photodiode detectors. Wherein determining the position of the center of the wafer includes applying position data from the robotic arm to a Kalman filter. The method further includes updating the Kalman filter based on the sensor data. The wafer is substantially circular. The wafer includes an alignment notch. The plurality of sensors including one or more detectors arranged to face light emitting diodes such that the path of light from the light emitting diode to the detector includes a predetermined location within the internal structure. The plurality of sensors include one or more detectors, wherein when the detectors are reflected from a wafer in a pre-designated position, light from the light emitting diodes is arranged to be detected by the detector. The operation of inserting the wafer includes an operation of linearly moving and inserting. The operation of moving the wafer includes an operation of linearly moving the wafer. The step of rotating the robot arm includes the step of rotating about the central axis of the robot arm. Wherein the act of detecting the presence of the wafer comprises the steps of: detecting a first movement in the one of the plurality of sensors from the presence of the wafer to the absence state; Wherein the path of the wafer from the first movement to the second movement may be nonlinear. The path includes an arc formed from the rotation of the wafer.

In another aspect, an apparatus for handling a wafer includes: an internal structure accessible through a plurality of inlets; And a plurality of sensors each configured for two of said plurality of inlets, wherein each sensor detects the presence of a wafer at a pre-designated location in said internal structure, and wherein at least two of said plurality of sensors The plurality of sensors are arranged so as to detect the wafer at any position of the wafer completely contained within the wafer.

The plurality of inlets include four inlets. The plurality of inlets include seven inlets. The plurality of entrances include eight entrances. The plurality of inlets include an optical sensor. The plurality of sensors include one or more light emitting diodes. The apparatus further includes a robotic arm having a central axis within the internal structure, the robotic arm including an end effector for handling the wafer.

In yet another aspect, an apparatus for handling a wafer, the apparatus comprising: an internal structure accessible through a plurality of inlets; And a plurality of sensors each configured for two of the plurality of inlets, wherein each sensor detects the presence of a wafer at a pre-designated location in the internal structure, and wherein a first pair of sensors detect each of the plurality of inlets Wherein the plurality of sensors are arranged such that a second pair of sensors are disposed just outside the maximum diameter of the wafer linearly input through each of the plurality of inlets, One of the first pair of sensors and the second pair of sensors shares an adjacent one of the plurality of inlets.

The plurality of inlets include four inlets. The plurality of inlets include seven inlets. The plurality of entrances include eight entrances. The plurality of sensors includes an optical sensor. The plurality of sensors include one or more light emitting diodes. The apparatus further includes a robotic arm having a central axis within the internal structure, wherein the robotic arm includes an end effector for handling the wafer.

In another aspect, a wafer handling apparatus for handling a wafer includes: an internal structure that approaches through four inlets; And eight sensors, each sensor detecting the presence of a wafer at a pre-designated location within the internal structure, the sensor being arranged in two square arrays centered on the center of the internal structure, Are sized such that the first array of the two square arrays is smaller than the second array of the square arrays and the group of four sensors located at the opposing vertexes of the two square arrays are aligned on the same line.

The eight sensors include an optical sensor. The eight sensors include one or more light emitting diodes. Further comprising a robotic arm having a central axis within the internal structure, the robotic arm including an end effector for handling the wafer.

In another aspect, an apparatus according to the present invention is a robotic arm for handling a wafer, said robotic arm comprising one or more encoders that provide encoder data identifying the location of one or more components of the robotic arm In-robot arm; And a processor for applying an extended Kalman filter to the encoder data to predict the position of the wafer.

The location includes the wafer center and / or wafer radius. The position is determined with reference to the end effector of the robot arm. The position is determined with reference to the central axis of the robot arm. The processor recalculates the position whenever new encoder data is received. New encoder data is received at 2 kHz. The processor updates one or more equations of the Kalman filter using movement data from one or more sensors that detect the presence or absence of a wafer at one or more predetermined locations in the robot wafer handler.

In another aspect, a method in accordance with the present invention is a method comprising: placing a plurality of sensors in an internal structure of a wafer handling apparatus, each of the plurality of sensors moving a wafer between a presence and absence state of a wafer at a pre- Detecting; The robot arm including one or more encoders that provide encoder data identifying a location of one or more components of the robotic arm; And applying the encoder data to an extended Kalman filter to provide a predicted position of the wafer.

The method includes detecting movement in one of the plurality of sensors to provide an actual position of the wafer; Determining an error on the actual location and the predicted location; And updating one or more variables for the extended Kalman filter based on the error. The step of applying the encoder data comprises calculating the wafer position every 0.5 milliseconds. The predicted position of the wafer includes the center of the wafer. The predicted position of the wafer includes the radius of the wafer.

In another aspect, an apparatus according to the present invention includes: an inner chamber having a plurality of inlets shaped and sized as one or more wafer passages; A contact image sensor arranged to scan a wafer in the inner chamber; A robot in an interior chamber comprising an end effector for handling the wafer, the robot acquiring an image of the wafer by moving the wafer into a measurement volume of the contact image sensor; And a processor for processing the image of the wafer and determining the center of the wafer.

The robot moves the wafer linearly through the measurement volume of the touch sensor image. The contact image sensor is disposed so as to be perpendicular to the path of the wafer. The contact image sensor is disposed at an angle of 45 degrees in the path of the wafer. The robot moves the wafer in a curved path through the measurement volume of the contact image sensor. The robot moves the wafer in a discontinuous path through the measurement volume of the contact image sensor. The robot rotates the wafer within the measurement volume of the contact image sensor. The robot lifts the wafer with the measurement volume of the contact image sensor. The robot includes a rotary chuck on an end effect that rotates the wafer. The rotary chuck rotates between 180 degrees and 360 degrees. And a rotation chuck for lifting the wafer from the end effector to a measurement volume of the contact image sensor. And the contact image sensor is at least 300 mm long. The contact image sensor has a length exceeding the diameter of the wafer. The contact image sensor is disposed at one of the plurality of inlets for the internal structure. Further comprising a plurality of contact image sensors, each of the plurality of contact image sensors being located at one of a plurality of inlets for the interior structure. The contact image sensor is disposed across the center of the internal structure. Further comprising a second contact image sensor, wherein the contact image sensor and the second contact image sensor are collinearly positioned. Wherein the contact image sensor and the second contact imager sensor are located at one of the plurality of inlets for the internal structure. The apparatus may comprise a plurality of collinear contact image sensor pairs located at each of the plurality of inlets for the internal structure. The apparatus may include a second pair of contact image sensors in a collinear fashion. The collinear second contact image sensor pairs are arranged to cross the center of the internal structure. The plurality of inlets may include four inlets. The plurality of entrances may include eight entrances. The processor may further identify an alignment notch on the wafer. The processor can further determine the radius of the wafer.

In another aspect, a method according to the present invention includes positioning a contact image sensor to capture image data from an internal structure of a robotic wafer handler; The contact image sensor passing over at least a portion of the wafer to obtain an image; And determining a center of the wafer based on the image. The step of the contact image sensor passing over at least a portion of the wafer includes linearly moving the wafer through a measurement volume of the contact image sensor.

In another aspect, an apparatus according to the present invention is a robot arm in a robot chamber, said robot arm comprising an end effector for handling a wafer; And a linear array of charge-coupled devices within the internal structure of the robot chamber, wherein the linear array is arranged to acquire image data from a measurement volume at one or more pre-designated locations in the robot chamber do.

The apparatus may include an external illumination source for illuminating the linear array. And a wireless power coupling to provide inductive power to the linear array. And a wireless transceiver for wirelessly exchanging data using the linear array. The wireless transceiver may be located outside the robot chamber. The data includes image data. The linear array is a 1-by-n array of charge-coupled devices. The linear array includes a two-dimensional array of charge-coupled devices. The apparatus may include a plurality of linear arrays each capturing image data at different locations within the internal structure. The robot arm includes a chuck on an end effector that rotates the wafer within a measurement volume of the linear array. The robot arm lifts the wafer with the measurement volume of the linear array. The chuck rotates between 180 degrees and 360 degrees. The apparatus may include a rotating chuck for lifting the wafer from the end effector to a measurement volume of the linear array. The apparatus may include a processor for determining the center of the wafer using the image data. The apparatus may include a processor for determining the radius of the wafer using the image data. The apparatus may further comprise a processor for identifying the alignment notch on the wafer using the image data.

In another aspect, an apparatus according to the present invention includes a robot arm in a robot chamber, the robot arm including an end effector for handling a wafer; And a linear array of typical engaging elements on the end effector arranged to capture edge data from a wafer placed in the end effector.

The apparatus may include an external illumination source for illuminating the linear array. The apparatus may include a wireless power coupling that provides inductive power to the linear array. The apparatus may include a wireless transceiver for wirelessly exchanging data using the linear array. The radio transceiver is disposed outside the robot chamber. The linear array is a 1-by-n array of charge-coupled devices. The linear array includes a two-dimensional array of charge-coupled devices. The robot arm includes a chuck on an end effector that rotates the wafer within a measurement volume of the linear array. The apparatus includes a rotating chuck that lifts the wafer from the end effector and rotates the wafer within the measurement volume of the linear array. The apparatus may include a processor for determining the center of the wafer using the edge data. The apparatus may include a processor that uses the edge data to determine a radius of the wafer. The apparatus may further comprise a plurality of linear arrays arranged to capture edge data from a plurality of locations on the surface of the end effector.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be fully understood and its practical effect, preferred embodiments of the invention, but not limited thereto, are described below with reference to the accompanying drawings.
1 is a top view of a wafer handling module including eight sensors for detecting the position of a wafer, in accordance with the present invention;
2 is a top view showing a wafer handling module including four sensors for detecting the position of the wafer.
3 is a diagram illustrating a generalized process for wafer center search.
4 is a diagram illustrating a wafer detection process using a Kalman filter.
5 is a diagram showing an apparatus including a linear image sensor.
6 is a top view showing a contact image sensor used for wafer center search using linear wafer motion;
7 is a top view showing a contact image sensor used for wafer center search using curved wafer motion.
8 is a top view showing a contact image sensor used for wafer center search using rotating wafer motion.
9 is a diagram showing a pair of linear CCD arrays used for wafer center search using linear wafer motion.
10 is a diagram showing a single CCD array used for wafer center search using rotating wafer motion.
11 is a diagram showing four CCD arrays used for wafer center search using multiple wafer motion.
12 is a view showing a CCD sensor on a robot arm and an effector.
13 is a view showing a single CCD sensor on an effector using a rotary chuck.
14 is a diagram showing a single CCD in a robot handling module.

In the following, the invention will be described in detail with reference to the accompanying drawings and examples.

The term "wafer" used below is an abbreviation for all substrates and all other materials that may be handled in a semiconductor manufacturing system. The following description applies to wafers and refers to the wafers used in various embodiments, but a variety of other objects may be covered in the semiconductor facility, including manufacturing wafers, test wafers, cleaning wafers, calibration wafers, (E.g., a reticle, a magnetic head, a flat panel, etc.) including a substrate having various shapes such as a square or rectangular substrate. All such workpieces are included within the scope of the term "wafer " used in this specification unless the context clearly dictates otherwise.

1 is a top view of a transfer robot handling module. In the module 110, a substantially round wafer 120 can be handled by a robot (not shown, having a central axis 160), while at the same time the sensor detects the presence (or absence) of the wafer 120 do. Generally, the module 110 has an interior that is substantially circular. The circular inner structure 170 has a ring sufficiently suitable for rotation of the wafer and the robot between various inlets (not shown) for the module 110. Additional space may be provided and the shape may be any geometric shape that may assist in the movement of the wafer but it is generally understood that the shape of the circle minimizes the volume within the vacuum environment maintained by the module 110 and other associated hardware This provides the advantage.

Also, generally, two or more entrances are formed to allow the wafer 120 to pass therethrough, along with any portion of the robotic arm needed to place or pull the wafer 120 out of the module 110, Is provided to the determined module. Generally, the size of each inlet is wide and long enough to accommodate a single wafer, along with the end effector and other parts of the robot that must pass through the inlet during handling. This size is optimized by the robot moving the wafer linearly through the center of each inlet, effectively preserving the valuable volume within the vacuum environment. Semiconductor wafers generally have the form of an odd circle as provided in industry standards. Such wafers also include notches for continuing rotational alignment during the process, and as will be described in greater detail below, identifying or detecting such notches may require additional processing during wafer center detection . However, more generally, the wafer may have various shapes and / or sizes. For example, 300 nm is a common size for current wafers, but a new standard for semiconductor manufacturing processes provides a size over 400 nm for wafers. Furthermore, certain substrates have different shapes, such as rectangular substrates used in flat panners. Thus, the shape and size of the components (and spaces) devised for wafer handling can vary, and one skilled in the art can understand how to apply components, such as entrances, to a particular wafer size.

In one embodiment, the module 110 includes four entrances, one on each side of the module 100. The module 110 may also include a different number of entrances, such as two or three. Further, while the square module 110 has been represented, the module 110 may have other shapes (commonly used in cluster processes), such as general polygons such as rectangles or hexagons, hexagons, octagons, and the like. A rectangular shape may include multiple entrances on one side, and a typical polygon includes one entrance on each side. Thus, a square device 110 having one inlet on each side is a common device useful for semiconductor manufacturing processes, and many other shapes may be suitably adapted for use in manufacturing facilities and are within the scope of this specification.

As shown, the sensor may include eight sensors 131-138 aligned with two square arrays 141, 142 disposed centrally with respect to the central axis 160 of the robot. The sensors are arranged such that four of these sensors 131-134 form a first internal array 142 and four of the remaining sensors 135-138 form a second external array 141. [ The layout of such a sensor is well understood with reference to FIG. 1, and the layout of other features is described as follows. Two concentric square arrays 141 and 142 are arranged such that the vertices form a pair of sensors 150 from the inner array 142 and the outer array 141. The arrays 141 and 142 are further arranged cyclically such that the four sensors from the opposite vertexes of the two square arrays 141 and 142 are collinear and are positioned at the center of the internal structure 170, (Line) intersecting the central axis 160 of the first substrate 110. [ This final restriction is not necessary. That is, the robot may include more than one axis, and the robot may be modified to accommodate various rotational movements that do not require an axis at the center of the internal structure 170. However, the layout described above is a general practical layout for a robot handler that provides 360 degrees of freedom of movement. When the wafer 120 is first input (or withdrawn) from one of the inlets to the inner structure 170 (which is generally centered on each side), two sensors from the inner array 142 detect the wafer And two sensors from the outer array 141 are disposed just outside the diameter of the wafer 123 on either side. In this manner, the ratio of only two sensors is maintained for each inlet, and in all cases where the wafer 120 is in the internal structure 170, more than one sensor detects the wafer 120, The above sensor immediately detects the rotational movement of the wafer 120 within the internal structure 170. As an excellent effect, this structure also allows the wafer 110 to be held within the internal structure even after the module 110 and the sensors 131-138 are powered, for example, even after a power failure condition, It is possible to always detect whether or not there is a < / RTI >

A similar arrangement may be provided for modules having 5, 6, 7, 8, or the entrance of the garment. Generally, each inlet may include two sensors on each side, wherein the first sensor is arranged to detect the wafer when it is completely moved from the inlet to the internal structure, and the second sensor is located just outside the diameter of the wafer . In this embodiment, each pair of sensors from the inner and outer arrays can be shared with neighboring entrances, i.e., immediately adjacent entities located on either side.

Figure 1 shows a specific device consisting of sensors 131-138, but other criteria can be used to determine suitable sensor elements and placement. For example, during a movement sequence in which a wafer is drawn out of the stasis and placed into another station, it is effective for the sensor arrangement to provide at least four points around the edge of the wafer. The group of three pointers used to predict the center and the radius is greater than 60 degrees between any three or more points and is greater than 180 degrees between any three points used to determine the center and radius (I.e., a 180 degree section does not lack the point defining the edge). Extra points can be used effectively to improve predictions through direct calculations or to identify a calculate circle. It is effective that the sensor is disposed within the swing ring of the link of the robot arm, with fiducial marking capable of reliably and repeatedly operating the sensor.

The sensor device may also be applied to a particular end effector. For example, a fork-type ent effect carries the wafer around the lateral edge. However, it is not supported from the front. For a typical wafer size, this leaves a 250 nm wide area in the middle of the fork. However, none of the side edges can be used for detection. For a paddle-type end effector, the center (150 nm) opening the centerline of the linear extension is opened for sensor placement. However, the rear end of the wafer facing the wrist of the robot arm can be completely lowered from the sensor by the end-effector.

The sensors 131-138 are generally operative to detect the presence of a wafer at a pre-designated location within the internal structure 170. As used below, the detecting operation of presence includes an operation of detecting a member as well as detecting a change between absence and presence of the wafer. Many techniques, such as a reflection technique in which the light source is reflected back toward the light source in the presence of the wafer or a beam-breaking technique in which the beam between the light source and the sensor is destroyed in the presence of the wafer, Can be suitably used. In one embodiment, the sensors 131-138 use a light emitting diode or laser light source that includes an autofocus photodiode detector (which facilitates alignment during installation operations). The sensor described above can be used and provided in a similar manner so that one cost effective solution for detecting the presence of a wafer in a predefined position or other sensor technology can be applied to the vacuum semiconductor environment. This may include, for example, sonar, radar or other electromagnetic or distance or position sensing technology.

The distance between the inner array 142 and the outer array 141, or the distance between each pair of sensors 150 therein, will generally be determined by the size of the wafer to be handled by the system. In one embodiment, the positions of the sensors can be adjusted to form larger or smaller arrays, while maintaining the linear and diagonal relationships described above. In this way, the module 110 can be easily applied to wafers of different sizes.

During normal operation, the sensors 131-138 may detect the position of the wafer 120 using a circular model, a linear model (e.g., the Kalman filter technique described below), or other suitable mathematical, neural network, inductive, It is used to determine the center position. The method of detecting the wafer position or sensor is described in more detail below. In general, the following techniques use a combination of data from the encoder for one or more robot handlers that provide data from sensors 131-138 and data related to the location of the robotics components. The following discussion focuses on sensor and encoder data, but time may be used explicitly or implicitly in wafer center search operations, as detected by a clock or signal in the system.

Figure 2 is a top view of a wafer handling module including four sensors for detecting the position of the wafer. In this embodiment, the system 200 can use only one sensor 202 for each inlet. The sensor 202 may be any of the sensors described above. In this case, the sensor 202 is preferably positioned adjacent each entrance and within the diameter of the wafer 204 so that one or more edge detections can be made as the wafer passes over any of the entrances. As shown, the wafer handling module 210 is generally square and includes four inlets, each entry including one sensor 202 associated therewith.

Figure 3 shows a generalized process for wafer center search.

Generally, a robotic arm (such as any of the robotic arms described above) can be involved in various operations to carry a wafer (any of the wafers described above) from one location to another during a semiconductor manufacturing process . This is the operation of withdrawing the wafer from the first position as shown in step 302, the act of inserting the robotic arm into any of the above described modules as shown in step 304, The act of rotating the robotic arm toward the other entrance to the entrance, the act of unfolding the robotic arm through such an entrance as shown in step 308, and the act of placing the wafer in the second position as shown in step 310 do. The first and second locations may be used for other robotic handlers, load locks, buffers or transfer stations, any type of process module, and / or other processes for basic processes such as cleaning, metrology, scanning, May be in any location within the manufacturing facility that includes the module. As shown in Figure 3, this process can be repeated infinitely as the wafer is moved into or out of the facility and processed by various process modules. While not explicitly shown, during such operations (e.g., opening or closing of the internal structure of the inlet shutoff valve, or waiting in the internal structure for access to various resources) Can be performed. Details of various robot handling operations are well known in the art, and such robotic arms or handling functions may be suitably employed using the process shown in FIG. This includes various combinations of deployment, insertion and rotation operations of the robotic arm, Z-axis movement of the robotic arm, and other optional operations that may be usefully employed in wafer handling.

While the robotic arm is being controlled in the wafer handling operation as described in step 302, the encoder provides data relating to the position of the robotic arm, the position (rotational direction) of the driving element directly controlling the position of the robotic arm, Thereby providing data. This data may be received for the process as shown in step 320. [ As shown in step 330, sensor data (any one of the sensors described above, which detects the presence, absence, or presence and absence of a wafer present at a pre-designated location in the robot handler, Is received. The physical data for such sensor operation is received in various forms, including the presence of optical signals, absence of optical signals, intensity of optical signals, or binary signals that encode any of the above.

As shown in step 330, encoder data and sensor data may be applied to calculate position data for a wafer, such as alignment, wafer sensor, and the like. Details of various algorithms for calculating wafer positions are now provided. Although not explicitly shown, a controller or other device that calculates the wafer position applies this data in various manners to control additional movement of the robotic arm. In particular, such data can be used for accurate placement of the wafer in the final position. It can also be used as an initial estimate of the position of the wafer when the data is stored and the same wafer is pulled out for further movement.

In the four sensor embodiments shown in Fig. 2, four entrances, a wafer (not shown) for the transfer path that is useful for moving the wafer from the position where wafer edge data (obtained in accordance with the change in step 330) It is used to determine the center. The sensor position, robot position, and final position (e.g., in the process chamber or loadlock) are defined in the world coordinate system. The world coordinate system determines the relative location of these or other elements in the wafer processing system including the wafer handling robot module. The world coordinate system can be effectively set with respect to the sensor position.

Through training, the controller can use the robot position or encoder data, e.g., sensor data to detect multiple faces of the robot entropy effect, and recording concurrent values from the encoder, Associate. The controller thus maps the encoder value to the world coordinate system so that the world coordinate position of the robot as the robot moves is known. The controller likewise determines the world coordinates (e.g., the end point) of other elements in the wafer processing system to produce a world coordinate map of the elements of the wafer processing system. The associated movement of the robot position and the world coordinate system may also be performed manually (or alternatively) using a calibrated fixture or an installation tool carried by the robot. The foregoing description is provided by way of example, and techniques for associating robot coordinates with world coordinates are well known and may be used more advantageously using the system described herein. For example, a sensor-based world coordinate system may be performed using one possible approach, or a similar sensor search function using an end-effector-based world coordinate system.

After the robotic arm is properly trained, the sensor data is acquired while the wafer is being handled through an insert / rotate / expand (unfold) operation, as shown in FIG. A large number of techniques are suitably employed to determine the position of a wafer moving from a top to a non-linear path to a plurality of sensors having predefined locations. These various techniques will be described in detail below by way of example, but the present invention is not limited thereto.

To predict the center and radius of a wafer, world coordinate edge point data can be applied to simultaneous circle equations. These equations can be transformed into a matrix form, and a so-called pseudo inverse can be used to provide one or more least square solutions as a matrix (see, for example, Academic Press, Inc. 1980), which is incorporated herein by reference in its entirety). This solution minimizes the square error between the edge of the circle and the detected edge point. From this solution, the sensor position and radius can be calculated. Mathematically speaking, the general equation for a circle is expressed as

This can be reformulated as follows.

here,

D ≡ -2 x _c , E ≡ -2 y _c , F ≡ x _c ² + y _c ² - r ² to be.

Given n points from the circumference of these circles, the matrix of n equations is

If there are three points, the A matrix is squared and this solution can be represented by inversely transforming the A matrix as

When three or more points are used, a pseudo inverse is used to provide a least squares solution to the above problem. This is indicated as follows.

This solution minimizes the square error between the edge of the circle and all points. From the solution to the vector (x), the center position and the predicted radius for the circular wafer can be calculated by D, E and F. [

For notch detection, the distance from the calculated center to each detected point can be determined, and after the center and radius have been recalculated, the point that is not suitable for the desired circle (using the appropriate metric) Can be removed. An alignment notch can be detected in such calculations by identifying a detected edge point that deviates from a circle calculated above some predefined threshold or tolerance. For the purpose of center detection, these points can be eliminated. General information about the geometry of the wafer may be used to detect (and exclude from subsequent calculations) points that are likely to be associated with the robot components rather than the wafers. In one aspect, the system can distinguish anomaly adjacent to the expected circumference (which is likely due to the alignment notch) and anomaly far from the expected circumference, so that the rotational alignment of the wafer is recovered . Generally, this distinction operation is based on the relative magnitude of the deformation, with the general notion that the robotic arm generally causes the wafer to unexpectedly exist, while the alignment notch is characterized by the absence of an unexpected wafer.

In addition, various events that occur during the movement (e.g., radial displacement, linear displacement, or simple or complex movement of the wafer with respect to the entrainers) can be detected, and techniques well known to those skilled in the art Can be detected and considered.

A large number of functions related to wafer detection can be effectively performed. For example, the system designed in this specification calculates the link offset for the robotic arm, measures the sensor position, measures the light beam width for the optical sensor, calculates the wafer center position for the end effector, To determine when a slotted velvet door is open or blocked, and to accurately position the wafer within the process module, the loadlock, and other link modules within the fabrication facility. A number of related process embodiments are provided below.

With the aid of a suitable center search technique that is different from the techniques described above, the robot handler and sensor can be operated to determine the position of the wafer. In one embodiment, the system tracks sensor data during an insert operation (step 304) and a rotate operation 306 and visualizes wafer center calculations for the start (step 308) of an extended (spread) operation. In one embodiment, after rotation, the processor may simultaneously calculate the radius and the angle of the wafer center (e.g., using a least square fit as described above), and the appropriate world coordinate system (e.g., end effector, module Etc.). ≪ / RTI > This predicted radius is compared to the expected value, and anomaly is detected and removed. An error vector is then derived from this measurement for subsequent sensor movement and applied to estimate the expected path for the wafer. Thus, in one embodiment, the robot handler collects sensor data during insertion and rotation operations, and calculates the wafer position while collecting additional sensor data during the extension operation.

Other techniques may be used for center search operations (calculations). In one embodiment, a real-time encoder update (e.g., every 0.5 milliseconds every 2 milliseconds, every 50 milliseconds, or any other suitable period or time increments), along with time data for each sensor movement event Using this, a Kalman filter can be used.

4 shows a wafer center search method using a Kalman filter. Generally, as shown in step 330, the operation of calculating the wafer position may be performed using a Kalman filter that applies encoder data to determine wafer position or predict sensor movement. However, as a variation on the general method shown in FIG. 3, the (center search) Kalman model may be updated periodically. More specifically, the sensor data may be received at each sensor movement, including the movement time and, as appropriate, the identification and / or location of the sensor, as shown in step 330. Based on this data, an error between the expected travel time for the location and the measured travel time is calculated, as shown in step 410. [ This error data can then be used to update the Kalman filter for more accurate subsequent prediction, as shown at step 420. [ Thus, in general, the actual detected movement (change) is used, for example, to update the center-search model, such as the equation of the determined Kalman filter, while the encoder data is used to update the wafer center data for control of the robotic arm Used to provide.

As an example, for a wafer that is seeded at a particular position (Xe, Ye) and moves at an expected velocity and acceleration (V, a), the model predicts sensor start at time (te) ) To identify the actual movement. An error occurs in which the encoder position (or optionally the time stamp) measured at time ts is expressed as:

Thereafter, an extended Kalman filter equation can be used, for example as described in Arthur-Gelf, Applied Optical Prediction (MIT Press 1974). An application example of the equation described in the book of Gelf is the system model as follows,

As a measurement model,

Can be mentioned.

Here, state estimate propagation is defined as:

이고,

ego,

The error covariance propagation

이다.

to be.

As a significant effect, this generalized technique allows more individual sensor events to be used rather than requiring a certain number of points (e.g., three) to identify a circular wafer. The steps in a particular sequence are shown in FIG. 4, and the operations shown are repeatedly performed during operation of the robot wafer handler, and the order or timing of the steps is not implied. Nevertheless, in some implementations it is generally true that encoder data is continuously provided in real time, and transitions that initiate model updates occur intermittently as the wafers are moved by the robot. In addition, 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.

The methods and systems described above can generally be applied to wafer center detection operations that utilize the detection of wafers at different points. It is also possible to use a number of linear sensors, such as a linear array of charge coupled devices (CCD) or contact image sensors, for capturing wafer data of linear segments. A plurality of devices using linear sensors are described below. In this technique, the center search is generally obtained through a direct analysis of the image data, rather than as a result derived from a plurality of distinct sensor events, as in the technique described above.

Figure 5 shows an apparatus comprising a linear image sensor for capturing image data from the passed wafer. The apparatus 500 may include an upper surface 502, a bottom surface 504, an inner structure 506, a linear image sensor 508, a light source 510 and a wafer 512.

Device 500 may be any device used in semiconductor manufacturing processes, such as, for example, load locks, buffers, aligners, robot handlers, and the like. In one embodiment, the apparatus 500 is a Robert handler including a robotic arm (not shown) having an end effector for handling the wafer.

The upper surface 502 and the bottom surface partially surround the inner structure 506. Although not shown, the apparatus 500 may include, for example, a side wall (not shown) that includes a plurality of inlets for passing a wafer therethrough, along with a slot valve or other shut-off mechanism to block the internal structure 506 of the apparatus 500 ). In general, the shape and size of the various surfaces of the device 500 are not critical. However, one or more of the surfaces must be parallel to the plane of travel for the wafer, so that the image sensor can be placed on its surface to capture image data from the wafer moving through the internal structure 506.

The linear image sensor 508 may be disposed on the top surface 502 of the device 500 or on the bottom surface of the device as shown. In one embodiment, the linear image sensor 508 may be a contact image sensor (CIS). A commercially available contact image sensor generally comprises a linear array of detectors (CCD), including an integrated focal lens and a light source 510, such as an LED located on the side of the linear sensor array. Conventional contact image sensors use a broad spectrum light source similar to red, green, and blue LEDs, but the wafer may be suitably imaged to perform a center search operation using only a monochromatic light source such as a red LED. Generally, a contact image sensor is disposed adjacent to an object to be scanned. In another embodiment, linear image sensor 508 may comprise a linear array of charge coupled devices (CCD or complementary metal oxide semiconductor (CMOS).) The linear array may include n sensors (e.g., 128 sensors, By-n arrays, 2-by-n optical sensors, or other suitable one-dimensional or two-dimensional arrays that include a number of sensors suitable for scanning Or devices) provide higher resolution than current CIS devices and may be located further away from the imaged object. However, they require additional external illumination for good quality image capture. Lt; RTI ID = 0.0 > of the < / RTI > diameter of the pre-packaged array, providing an inexpensive alternative to image capture, By suitably applying to some applications, both techniques are suitable for use with the embodiments described in this specification, but each provides an opportunity to make it more suitable for a particular application. However, as described above, any one or other of these techniques, as used herein, may be usefully employed as the linear image sensor 508. The linear image The sensor 508 has a field of view and a measurement volume over which the image data can be captured. In general, the linear evacuation sensor 508 can be used to detect ambient light, desired image accuracy, And an operating measurement volume determined according to a number of factors.

The wafer 512 may pass through the device 500 in a linear path, as indicated by arrow 514. One possible path of travel for the wafer is the linear path, or many other movements can be applied by the robot handler. For example, the wafer may move in a curved path using rotational motion of the robot, or may move in a discontinuous path composed of a plurality of different linear and / or curved paths. As will be explained further below, the wafer may be additionally or alternatively rotatable relative to the axis. The data obtained from these scans are typically directly analyzed to position the wafer center and obtain wafer position data (e.g., direction of rotation, radius, etc.). The image data thus obtained should be coordinated with the robot motion, using encoder data or other sensor data, to correctly interpret the image data.

6 is a top view showing a contact image sensor used for wafer center search using linear wafer motion. A single CIS 608 disposed at right angles to the direction of movement 606 of the wafer 602 having the alignment notch 604 may be moved in a linear motion (Indicated at 602). In an embodiment, the CIS 608 may comprise a single module having a length of 310 millimeters and may be disposed across the inlet to the device to provide overall wafer detection, As it moves in or out, a notch / alignment detection operation can be performed. This type of wafer detection provides virtually photocopy of the wafer 602, as alignment and size are obtained directly by image analysis. As a significant effect, this arrangement provides an overall wafer scan without requiring additional robotic arm motion or the like. Thus, the throughput for the transfer device can be progressed at a speed limited only by the robot and other limiting factors. In another embodiment, such a CIS 608 can be placed at each of several entrances, e.g., at four entrances of a square robot handler, at various entrances. A single CIS 608 may additionally or alternatively be arranged to traverse the center of the device. Using about 450 millimeters of CIS 608, a single CIS is placed at a 45 degree angle to all four entrances and traverses the center of the device to capture motion of all linear wafers passing through the device. While this arrangement can not capture all wafer size data for every movement through the device, it provides enough data for wafer center detection for possible motion, and additional motion (movement) is provided by the robot handler Thereby ensuring scanning of the entire wafer surface.

7 is a top view showing a contact image sensor used for wafer center search using curved wafer motion. A wafer 702 having an alignment notch 704 passes through a single CIS 708 in a curved movement (indicated by arrow 706) in an apparatus that may be any of the devices 500 described above . The resulting image data is typically processed to compensate for the non-linear path 706 taken by the wafer 702, but this arrangement is suitable for placement in various locations within the robotic handler where the robotic arm uses rotation Do.

8 is a top view of a contact image sensor used for wafer center search using rotational wafer movement. In a device such as one of those described above, a wafer 802 having an alignment notch 804 can be rotated about an axis centered on the CIS 808, as indicated by arrow 810 have. The robot handler places the wafer 802 at the bottom and center of the CIS 808 and then selectively lifts the wafer 802 closer to the CIS 808 for more accurate image acquisition. Subsequently, the wafer is rotated 180 degrees (or more) to obtain a full image of the wafer 802 including the alignment notch 804. The CIS 808 may be centered within the device (e.g., the central axis of the internal structure of the device, the central axis of the robot arm within the device, or the central axis of some other robot home position within the device). This arrangement effectively utilizes a half rotation of the rotary chuck to effectively stroke the entire scan, simplifying the design of the chuck and reducing the scanning time. Another advantage is that this arrangement can provide a full wafer scan, regardless of the wafer size (within the limitations of the CIS 808). Thus, a single system can provide full edge detection for various shapes and sizes.

FIG. 9 shows a pair of linear CCDs used for wafer center detection using linear wafer operation, which is disposed at the entrance to the device, such as, for example, any of the devices 500 described above. In this embodiment, a first linear array 902 and a second linear array 904 of CCDs may be provided across a portion of the linear path of the wafer 908. Arrays 920 and 904 may be disposed along the outer edge of the entrance to the device, such as a robotic handler, for example, to capture image data for each wafer passing through the entrance. Likewise, an additional pair of sensor arrays may be disposed at one or more additional entrances to the device. Such a configuration can effectively utilize a short linear array of CCDs that are already commercially available, but may not capture the alignment notch used to determine the rotational alignment of the wafer 908.

Figure 10 shows a single CCD array used for wafer center search using rotating wafer motion (movement). In this embodiment, a single linear CCD array 1002 can be placed on a lid or other suitable internal surface of a device such as a robot handler or any of the other devices 500 described above. After the wafer 1004 is properly positioned under the array 1002, the wafer 1004 is moved in the direction of the arrow 1006 to capture all edge data for the wafer 1004, including the location of the alignment notch 1008. [ (Motion) as indicated by < / RTI > For example, such an embodiment could use a robot handler and a rotating chuck that include z-axis motion, as described above. In this embodiment, however, the rotary chuck preferably rotates more than 360 degrees to ensure full capture of the edge data. In another embodiment, two colinear arrays at the opposite edges of the wafer 1004 may be used to perform a full edge scan using half rotation.

11 shows four CCD arrays used for wafer center search using multiple wafer operations (movement). As indicated above, the device, which is one of the described devices 500, includes four CCD arrays 1102 arranged in two collinear, intersecting lines so that they are substantially similar to those described with reference to Figure 1 To cover the wafer path. Wafer 1104 may pass through the internal structure of the device along path 1106, including straight and curved movement. In one embodiment, the wafer 1104 may be sufficiently inserted toward the center to ensure detection (result) of the alignment notch 1108 at some point during the combined (combined) movement of the wafer 1104.

12 is a top view showing a CCD sensor on a robot arm end effector. The robot arm 1200 for wafer handling includes a plurality of links 1202 and an end effector 1204. The end effector 1204 includes a plurality of linear CCD arrays 1206, which are arranged, for example, to identify the four edge positions of the wafer 1208 located thereon. As a significant effect, this arrangement places the wafer very close to the linear CCD array 1207, which provides very high image accuracy. Furthermore. Such a digit does not require z-axis or rotational movement by the end effector 1204. From Figure 12, however, it can be seen that this configuration may also not identify the alignment notch for many rotational directions of the wafer 1208.

13 shows a perspective view of a single CCD sensor on an end effector having a rotary chuck. In this embodiment, a single linear CCD array 1302 may be mounted on the end effector 1304 at a location for acquiring edge data from a wafer 1306 that is substantially centered on the end effector 1304. The end effector includes a single-axis rotatable chuck for rotating the wafer 1306 in a full circle (including detection of alignment notches, if any) to obtain complete edge data from the wafer 1306.

A plurality of external devices 1320 may support the use of the CCD array 1302. For example, an external light source is disposed inside the apparatus to illuminate the CCD array 1302. [ At this time, the end effector 1304 exists at a specific position. As another example, a CCD array 1302 is provided with an inductively coupled power source, such that the CCD array 1302 wirelessly powers in a vacuum environment. As another example, a radio frequency or other wireless transceiver may be used to receive image data wirelessly from the CCD. In this wireless configuration, the transceiver, power coupling, etc. are located away from the CCD array (e.g., the central axis of the robotic arm or some other location adjacent to the corresponding wireless system).

Figure 14 shows a single CCD sensor in a robot handling module. In this embodiment, a single linear CCD array 1402 and associated light source or other emitter may be mounted on the interior wall of a device such as a robotic handler or other device 500 as described above. The end effector 1404 positions the wafer 1406 such that the wafer 1406 is centered on a rotating chuck 1408 (separated from the end effector 1404) that includes the upper edge of the CCD array 1402 . The end effector 1404 provides z-axis movement as indicated by arrow 1410 to lower the wafer 1406 onto the chuck 1408. The chuck 1408 then rotates the wafer 1406 to be fully rotated to provide a scan for the entire wafer edge. In addition to the position data capture operation for the wafer 1406, this approach captures the direction of rotation of the wafer 1406 by detecting an alignment notch, if any, on the wafer 1406. 13, a device 1420, such as a light source, a wireless power coupling or a wireless data transceiver, may be coupled to the exterior of the module to enhance the operation of the wafer center retrieval system described herein, As shown in FIG.

A load lock, a robot handler, or a sensor within the transfer station (or on an end effector in certain embodiments), although the above techniques may be used at other locations within the manufacturing system. For example, any of the techniques described above may be suitably adjusted to be used as an alginer. Likewise, a number of techniques described above can be suitably adapted for use as measurement stations in other devices, such as a robot handler or transfer station. In this embodiment, the measurement station scans the wafer, and provides measurement work at a location lying on the z-axis from other robot activities, by providing space for the measurement station that does not block other input or output paths from the robot handler , The robot performs other wafer motion.

The methods contained herein may be implemented in specific combinations thereof suitable for monitoring or controlling hardware, software, semiconductor manufacturing robotic systems. Such a process may be implemented in one or more microprocessors, microcontrollers, scalable microcontrollers, programmable digital signal processors or other programmable devices, and internal and / or external memory. Additionally or alternatively, the process may be implemented in application specific integrated circuits, programmable gate arrays, programmable array logic, or other devices that process electronic signals or a combination of these devices. The process may also be implemented in computer program code, such as structured programming languages such as C, object-oriented programming languages such as C ++, or high-level or low-level programming languages (including database programming languages and technologies). These languages are compiled or interpreted to run on any of the above devices and processors, processor architectures, or a combination of different software and hardware. All such modifications are included within the scope of the invention included in this specification.

The above-described embodiments of the present invention are for illustrative purposes only and are not intended to limit the present invention to the described embodiments. Accordingly, it will be apparent to those skilled in the art that various changes and modifications can be made. Further, the detailed description of this specification does not limit the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims (20)

A robotic arm for manipulating the wafer, said robotic arm including one or more encoders that provide encoder data identifying the position of one or more components of the robotic arm;
Wherein the location of the wafer prior to the processor-estimate is configured to apply an extended Kalman filter to the encoder data to estimate the position of the wafer,
The processor recomputes position when new encoder data is received,
The processor updates one or more equations of the Kalman filter using transtion data from one or more sensors that detect the presence of a wafer at one or more designated locations in a robotic wafer handler
Device. The method according to claim 1,
The location includes the wafer center
Device. The method according to claim 1,
The location includes the wafer radius
Device. The method according to claim 1,
The position is determined with reference to the end effector of the robot arm
Device. The method according to claim 1,
Position is determined with reference to the central axis of the robot arm
Device. delete The method according to claim 1,
The new encoder data is actually received at 2 kHz
Device. delete Disposing a plurality of sensors within the interior of the wafer handling apparatus, each of the plurality of sensors being capable of detecting a change between the presence and absence of a wafer at a designated location within the interior;
Operating a wafer using a robotic arm, the robotic arm including one or more encoders that provide encoder data identifying a location of one or more components of the robotic arm;
Applying encoder data to the extended Kalman filter to provide an estimated position of the wafer, the position of the wafer prior to estimation not known;
Recalculating a position when new encoder data is received, and updating the extended Kalman filter upon sensor change detecting a wafer edge
Way. 10. The method of claim 9,
Applying the encoder data comprises computing the wafer position every 0.5 milliseconds
Way. 10. The method of claim 9,
Wherein the estimated location of the wafer includes a center of the wafer
Way. 10. The method of claim 9,
Wherein the estimated position of the wafer includes a radius of the wafer
Way. 10. The method of claim 9,
The estimated position of the wafer is determined with reference to the end effector of the robot arm
Way. 10. The method of claim 9,
The estimated position is determined with reference to the central axis of the robot arm
Way. 10. The method of claim 9,
Wherein the plurality of sensors includes four sensors
Way. 10. The method of claim 9,
The step of applying the encoder data may include repeating the estimated position each time encoder data is received
Way. 10. The method of claim 9,
The step of manipulating the wafer includes moving the wafer between two openings to the wafer handling apparatus
Way. 10. The method of claim 9,
The step of manipulating the wafer includes moving the wafer between a load lock and a process module,
Way. 10. The method of claim 9,
The step of manipulating the wafer includes moving the wafer between the first process module and the second process module
Way. 10. The method of claim 9,
Detecting a transition of one of the plurality of sensors to provide an actual position of the wafer;
Determining an error between the actual position and the estimated position,
Further comprising updating at least one variable for the extended Kalman filter based on the error
Way.

Images