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  Method and apparatus for on the fly positioning and continuous monitoring of a substrate in a chamberUSPTO Application #: 20060167583Title: Method and apparatus for on the fly positioning and continuous monitoring of a substrate in a chamber Abstract: A method and apparatus for positioning a substrate in a substrate processing chamber. The method includes placing the substrate on a substrate transfer blade, moving the substrate transfer blade to a first position located in a transfer chamber, and capturing at least one image that includes at least a portion of the substrate transfer blade and at least a portion of the substrate. The method also includes processing the image to determine a position of a predetermined portion of the substrate transfer blade and a position of predetermined portion of the substrate. The method further includes determining an offset between the position of the predetermined portion of the substrate transfer blade and the position of the predetermined portion of the substrate, and moving the substrate transfer blade to a second position located in the substrate processing chamber, wherein the second position is adjusted to account for the offset. (end of abstract) Agent: Applied Materials, Inc. Patent Counsel - Santa Clara, CA, US Inventor: Satish Sundar USPTO Applicaton #: 20060167583 - Class: 700218000 (USPTO) Related Patent Categories: Data Processing: Generic Control Systems Or Specific Applications, Specific Application, Apparatus Or Process, Article Handling, Article Storing, Retrieval, Or Arrangement (e.g., Warehousing, Automated Library), Particular Charging Or Discharging Apparatus The Patent Description & Claims data below is from USPTO Patent Application 20060167583. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] This present invention relates generally to semiconductor manufacturing equipment. More specifically, the present invention relates to controlling the position of a semiconductor substrate during processing. Merely by way of example, the invention has been applied to centering a semiconductor wafer inside a processing chamber. The method and apparatus can be applied to other applications as well such as positioning of disk drive substrates, flat panel display substrates, mechanical substrates, and the like. [0002] The processing of semiconductor wafers to form integrated circuits and the like generally requires a number of sequential processing steps. Generally, these processes include steps to create devices, conductors, and insulators on the substrate. Often, these processes are performed in a number of processing chambers, each chamber dedicated to a single process. Some semiconductor processing systems utilize a central transfer chamber to couple these dedicated processing chambers, forming a "cluster tool." Examples of these cluster tools include the families of PRODUCER.RTM., CENTURA.RTM., AND ENDURA.RTM. processing systems available from Applied Materials, Inc., of Santa Clara, Calif. [0003] Generally, a cluster tool includes a central transfer chamber that houses a robot to facilitate transfer of the substrate between the surrounding processing chambers. This central transfer chamber is generally coupled to at least one load lock chamber and one or more processing chambers. In some cluster tools, multiple robots are located in the central transfer chamber to facilitate the transfer of semiconductor wafers from the load lock chambers to the processing chambers. Generally, semiconductor wafers are stored in wafer cassettes and transferred to the central transfer chamber via the load locks in preparation for processing. The processing chambers are typically utilized to perform various processing steps such as etching, physical vapor deposition, chemical vapor deposition, ion implantation and the like. During wafer transfer operations, semiconductor wafers are supported on moveable wafer transfer blades. [0004] In order to accurately place the semiconductor wafers in a given processing chamber, control over the wafer handling and transfer process is typically exercised by the cluster tool. As the size of semiconductor device features has decreased, processing tolerances have become more stringent and the accuracy requirements for wafer handling have increased. For example, in some processing steps, the placement tolerance for positioning the wafer in the processing chamber has been reduced to smaller dimensions. [0005] Accurate placement of the semiconductor wafers in the processing chambers may be hindered by a variety of factors. For example, thermal expansion of the components that make up the wafer transfer blades may shift the position of the semiconductor wafer from a desired position. Additionally, motion of the wafer transfer blades may result in the semiconductor wafer sliding on the wafer transfer blade during motion of the wafer transfer blade. Consequently, the placement position of the semiconductor wafer inside the processing chamber may be inaccurate. [0006] Several methods and apparatus have been utilized to determine the position of wafer transfer blades and other components of a robotic transfer system. In one approach, the position of a wafer is determined by measuring a reference position of a robot utilized to transfer a wafer between chambers of a semiconductor manufacturing system. However, although the position of a robot and an associated wafer transfer blade may be accurately determined, the position of a semiconductor wafer supported by such a wafer transfer blade may be unknown. For example, although a semiconductor wafer may be accurately positioned on a wafer transfer blade at the location where the wafer is removed from the wafer cassette, the wafer may slide during the movement of the robotic assembly through the load lock and transfer chamber. In fact, sliding of the wafer on the wafer transfer blade may cause the wafer to become misaligned in an undetermined manner. Therefore, in the general case, even though the position of the robot or the wafer transfer blade may be accurately determined and controlled, the position of the semiconductor wafer may be undetermined. [0007] In another approach, an optical emitter that produces a collimated beam of light is disposed on the surface of a transparent cover on the surface of the wafer transfer chamber. Detectors also mounted on the surface of the chamber are tripped when the beam of light is interrupted by either the wafer or the wafer transfer blade. Thus, the system can determine the position of the wafer with respect to the wafer transfer blade. Based on the detected position, the system can correct for wafer position errors. Sensor systems of the type known to be used in this approach are generally accurate to .about.mils. As semiconductor device dimensions have decreased, increased handling accuracy is desirable, thus providing motivation for wafer handling apparatus with increased accuracy. [0008] Therefore, there is a need in the art for an improved method and apparatus for positioning and continuously monitoring the position of a semiconductor wafer in a processing chamber. SUMMARY OF THE INVENTION [0009] Embodiments in accordance with the present invention relate generally to semiconductor processing systems. More particularly, embodiments according to the present invention relate to the measurement and control of the position of a semiconductor substrate. In a specific embodiment according to the present invention, a method of centering a semiconductor wafer in a processing chamber is disclosed. [0010] In one embodiment of the method of the present invention, the method includes placing the substrate on a substrate transfer blade, moving the substrate transfer blade to a first position located in a transfer chamber, and capturing at least one image that comprises at least a portion of the substrate transfer blade and at least a portion of the substrate. The method also includes processing the at least one image to determine a position of a predetermined portion of the substrate transfer blade and a position of predetermined portion of the substrate. The method further includes determining an offset between the predetermined portion of the substrate transfer blade and the predetermined portion of the substrate, and moving the substrate transfer blade to a second position located in the substrate processing chamber, wherein the second position is adjusted to account for the offset. [0011] In an alternative embodiment according to the present invention, the method includes providing a substrate support disposed in the substrate processing chamber, providing a plurality of fiducial marks associated with the substrate support, and placing a substrate on the substrate support. The method also includes capturing an image comprising at least one of the plurality of fiducial marks disposed on the substrate support and at least a portion of the substrate, and determining an offset between a predetermined position of the substrate support and a predetermined position of the substrate. The method also includes repositioning the substrate on the substrate support in response to the offset. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 is a simplified schematic illustration of a substrate positioning apparatus according to an embodiment of the present invention. [0013] FIG. 2 is a simplified schematic illustration of a top view of a substrate transfer blade according to an embodiment of the present invention. [0014] FIG. 3 is a simplified schematic illustration of a top view of a substrate transfer blade according to an alternative embodiment of the present invention. [0015] FIG. 4 is a simplified perspective side view of a substrate processing apparatus according to an embodiment of the present invention. [0016] FIG. 5 is a simplified schematic top view of a portion of a transfer chamber according to an embodiment of the present invention. [0017] FIG. 6 is a simplified schematic illustration of a transfer blade with an integrated calibration field according to an alternative embodiment of the present invention. [0018] FIG. 7 is a simplified flowchart of a method of positioning a substrate in a substrate processing system in accordance with an embodiment of the present invention. [0019] FIG. 8 is a simplified schematic illustration of a portion of a substrate processing system including a processing chamber according to an embodiment of the present invention. [0020] FIG. 9 is a simplified schematic illustration of a perspective cut-away view of a substrate processing chamber and a substrate support with an integrated calibration field according to an embodiment of the present invention. [0021] FIG. 10 is a simplified flowchart of a method of positioning a substrate in a processing chamber in accordance with an alternative embodiment of the present invention. Continue reading... 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