Wafer position error detection and correction system
First Claim
1. A wafer position error detection system comprising:
- a wafer handling chamber having a vacuum sealable opening for admitting wafers from a region external to the wafer handling chamber;
at least one wafer holding chamber disposed adjacent to the wafer handling chamber, the wafer holding chamber having an opening large enough to admit a wafer, the wafer holding chamber including a valve for closing the opening;
a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, the wafer transport robot having a blade adapted for carrying wafers, wherein the blade defines a slot;
at least one detection sensor disposed to detect an edge of the slot and an edge of the wafer as the wafer is retracted from or placed into the wafer holding chamber;
a controller device responsive to the detection sensor, wherein the controller device identifies the distance between the edge of the slot and the edge of the wafer on the blade as the wafer transport robot is translated along the first coordinate direction, and detects as a function of said identified distance a condition in which a wafer disposed on the wafer transport robot blade is displaced.
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Accused Products
Abstract
A wafer position error detection and correction system determines the presence of a wafer on a wafer transport robot blade. The system also determines a wafer position error by monitoring the position of the wafer with respect to the blade with one sensor which is located proximate to each entrance of a process chamber. When a wafer position error is detected, the system determines the extent of the misalignment and corrects such misalignment if correctable by the wafer transport robot or alerts an operator for operator intervention. The system incorporates a transparent cover on the surface of the wafer handling chamber and four optical detection sensors disposed on the surface of the transparent cover, in which each sensor is placed proximate to the entrance of the process chamber. In addition, an I/O sensor is placed adjacent the I/O slit valve to detect and correct wafer position errors. The detection sensors direct light through the wafer handling chamber to reflectors on the floor of the transfer chamber which reflect the light back to the detector sensors. A detector within the detector sensor detects when the beam path from the position sensor to the reflector is uninterrupted. As a wafer is retracted out of a process chamber or a wafer cassette, the position of the wafer with respect to the blade is measured, thus determining whether the wafer is properly placed on the wafer.
223 Citations
31 Claims
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1. A wafer position error detection system comprising:
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a wafer handling chamber having a vacuum sealable opening for admitting wafers from a region external to the wafer handling chamber; at least one wafer holding chamber disposed adjacent to the wafer handling chamber, the wafer holding chamber having an opening large enough to admit a wafer, the wafer holding chamber including a valve for closing the opening; a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, the wafer transport robot having a blade adapted for carrying wafers, wherein the blade defines a slot; at least one detection sensor disposed to detect an edge of the slot and an edge of the wafer as the wafer is retracted from or placed into the wafer holding chamber; a controller device responsive to the detection sensor, wherein the controller device identifies the distance between the edge of the slot and the edge of the wafer on the blade as the wafer transport robot is translated along the first coordinate direction, and detects as a function of said identified distance a condition in which a wafer disposed on the wafer transport robot blade is displaced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of detecting and correcting a position of a wafer within a wafer position error detection and correction system comprising the steps of:
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transporting a wafer on a blade of a wafer transport robot, wherein the blade includes a slot and defines a center hole; identifying the distance between an edge of the slot and an edge of the wafer on the blade as an edge of the slot and an edge of the wafer passes through a detection sensor; determining a wafer offset value by comparing the wafer distance to a nominal wafer distance; detecting a condition in which a wafer disposed on the blade is displaced by more than a predetermined correctable displacement amount; adjusting a destination coordinate of the wafer transport robot in accordance with the wafer offset value; and suspending operation of the wafer processing system upon detecting that the wafer is displaced by more than the predetermined correctable displacement amount. - View Dependent Claims (16, 17, 18)
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19. A wafer position error detection and correction system comprising:
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a wafer handling chamber having a vacuum sealable opening for admitting wafers from a region external to the wafer handling chamber, the wafer handling chamber having at least a portion of a wall formed from a substantially transparent material; at least one wafer holding chamber disposed adjacent to the wafer handling chamber, the wafer holding chamber having an opening large enough to admit a wafer, the wafer holding chamber including a valve for closing the opening; a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, the wafer transport robot having a blade adapted for carrying wafers, wherein the blade has a slot and defines a center hole; at least one detection sensor disposed to detect an edge of the slot and an edge of the wafer as the wafer is retracted from the wafer holding chamber, the detection sensor including; a light source disposed external to the wafer handling chamber, the light source aligned to direct an incident beam of light through the substantially transparent material into the wafer handling chamber; a reflector disposed within the wafer handling chamber so that at least a portion of the incident beam of light is reflected from the reflector as a reflected beam of light, wherein the reflector directs the reflected beam of light through the substantially transparent material; and a detector disposed external to the wafer handling chamber to receive the reflected beam of light from the reflector, wherein the light source and the detector are disposed to detect an edge of the slot when the slot allows the reflected beam of light to reflect through the transparent material and to further detect an edge of the wafer when the wafer intercepts a beam of light as the wafer is retracted from the wafer holding chamber; and a controller device responsive to the detection sensor, wherein the controller device identifies the distance between the edge of the slot and the edge of the wafer on the blade as the wafer transport robot is translated along the first coordinate direction, detects as a function of said identified distance a condition in which a wafer disposed on the wafer transport robot blade is displaced and controls the wafer transport robot to correct for the displacement of the wafer. - View Dependent Claims (20)
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21. A method of detecting a position of a wafer in a processing system comprising the steps of:
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transporting a wafer on a blade of a wafer transport robot, wherein the blade includes an optically detectable reference point; identifying the distance between the blade reference point and an edge of the wafer on the blade as the blade reference point and an edge of the wafer passes an optical detection sensor; and determining a wafer position condition as a function of said identified distance. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A wafer positioning method comprising:
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transporting a wafer on a blade of a transport robot, wherein said blade includes a slot and a hole; identifying the distance between an edge of the slot and an edge of the wafer on the blade as an edge of the slot and an edge of the wafer passes a detection sensor; determining a wafer offset value by comparing said wafer distance with a nominal wafer distance; controlling said wafer transport robot to correct for said wafer offset value during subsequent wafer transport. - View Dependent Claims (31)
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Specification