Wafer positioning system

A wafer processing system comprising:

• a wafer handling chamber having a vacuum sealable first opening for admitting wafers from a region external to said wafer handling chamber;
• at least one wafer processing chamber disposed adjacent to said wafer handling chamber, said wafer processing chamber having a second opening large enough to admit a wafer, said chamber including a valve for closing said second opening;
• a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, said wafer transport robot defining a wafer transport plane;
• at least one position sensor disposed to detect an edge of said wafer as said wafer is transported by a detection position defined by an optical beam emitted by said position sensor within said wafer handling chamber, wherein said position sensor defines an optical beam direction disposed away from a normal to said wafer transport plane so that said optical beam emitted by said position sensor and incident upon said wafer reflects from said wafer to a position disposed away from said position sensor.

A wafer positioning system comprising:

• a wafer handling chamber, said wafer handling chamber having at least a portion of a wall formed from a substantially transparent material;
• a wafer storage apparatus within said wafer handling chamber having a plurality of locations for storing wafers;
• a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, said wafer transport robot having a blade adapted for carrying wafers;
• and
• at least one position sensor comprising:
• a light source disposed external to said wafer handling chamber, said light source aligned to direct an incident beam of light through said substantially transparent material into said wafer handling chamber;
• a corner cube reflector disposed within said wafer handling chamber so that at least a portion of said incident beam of light is reflected from said reflector as a reflected beam of light, wherein said reflector directs said reflected beam of light through said substantially transparent material;
• and
• a detector disposed external to said wafer handling chamber to receive said reflected beam of light from said reflector, wherein said light source and said detector are disposed to detect an edge of said wafer when said wafer intercepts a beam of light as said wafer is transported from said wafer storage apparatus to a position within said wafer handling chamber disposed away from said wafer storage apparatus.

A wafer positioning system comprising:

• a wafer handling chamber, said wafer handling chamber having at least a portion of a wall formed from a substantially transparent material;
• a wafer storage apparatus within said wafer handling chamber having a plurality of locations for storing wafers;
• a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, said wafer transport robot having a blade adapted for carrying wafers;
• and
• at least one position sensor comprising:
• a light source disposed external to said wafer handling chamber, said light source aligned to direct an incident beam of light through said substantially transparent material into said wafer handling chamber;
• a reflector disposed within said wafer handling chamber so that at least a portion of said incident beam of light is reflected from said reflector as a reflected beam of light, wherein said reflector directs said reflected beam of light through said substantially transparent material;
• and
• a detector disposed external to said wafer handling chamber to receive said reflected beam of light from said reflector, wherein said light source and said detector are disposed to detect an edge of said wafer when said wafer intercepts a beam of light as said wafer is transported from said wafer storage apparatus to a position within said wafer handling chamber disposed away from said wafer storage apparatus.

A wafer positioning system comprising:

• a wafer handling chamber, said wafer handling chamber having at least a portion of a wall formed from a substantially transparent material;
• a wafer storage apparatus within said wafer handling chamber having a plurality of locations for storing wafers;
• a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, said wafer transport robot having a blade adapted for carrying wafers;
• and
• at least one position sensor comprising:
• a light source disposed external to said wafer handling chamber, said light source aligned to direct an incident beam of light through said substantially transparent material into said wafer handling chamber;
• a reflector disposed within said wafer handling chamber so that at least a portion of said incident beam of light is reflected from said reflector as a reflected beam of light, wherein said reflector directs said reflected beam of light through said substantially transparent material;
• and
• a detector disposed external to said wafer handling chamber to receive said reflected beam of light from said reflector, wherein said light source and said detector are disposed to detect an edge of said wafer when said wafer intercepts a beam of light as said wafer is transported from said wafer storage apparatus to a position within said wafer handling chamber disposed away from said wafer storage apparatus;
• means for detecting a position of said wafer transport robot as said edge of said wafer intersects both a first detection position and a second detection position within said wafer handling chamber;
• a stepper motor controller which generates an interrupt signal;
• and
• means for checking the state of said position sensor in response to said interrupt signal.

A wafer processing system comprising:

• a wafer storage apparatus having a plurality of locations for storing a plurality of wafers;
• a wafer transport robot operating under computer control, said wafer transport robot being capable of placing a wafer at a location within said wafer storage apparatus and being capable of transporting a wafer from said wafer storage apparatus to a plurality of locations;
• a first wafer positioning system comprising:
• a first array of optical sensors generating a first data set corresponding to a first wafer edge position;
• means for detecting a first wafer position from said first data set corresponding to said first wafer edge position;
• and
• means for controlling said wafer transport robot in accordance with said detected first wafer position so that said wafer transport robot places a wafer at a predetermined position within a location of said wafer storage apparatus;
• and a second wafer positioning system comprising:
• at least one optical sensor disposed to generate a second data set corresponding to a second wafer edge position;
• means for detecting a second wafer position from said second data set corresponding to said second wafer edge position;
• and
• means for controlling said wafer transport robot in accordance with said detected second wafer position so that said wafer transport robot places a wafer at a destination position.

A wafer processing system comprising:

• a wafer handling chamber having a vacuum sealable opening for admitting wafers from a region external to said wafer handling chamber;
• a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction;
• a plurality of optical sensors disposed to detect an edge of said wafer as said wafer is transported within said wafer handling chamber past a first detection position and past a second detection position within said wafer handling chamber;
• means for detecting when each of said plurality of optical sensors is blocked;
• means for detecting a distance corresponding to a displacement of said wafer transport robot from a predetermined position, wherein said wafer transport robot is capable of returning to said predetermined position periodically during wafer transport operations;
• means for detecting the output states of said optical sensors when said wafer transport robot is disposed at said predetermined position;
• and
• decision means for switching between operating modes in response to a particular set of signals output by said plurality of optical sensors when said wafer transport robot is disposed at said predetermined position.

A method of positioning a wafer within a wafer processing system comprising the steps of:

• transporting a wafer with a wafer transport robot so that said wafer is transported by at least one wafer position sensor;
• detecting a wafer position as an edge of said wafer passes through a wafer detection position defined by said at least one wafer position sensor;
• calculating a wafer offset value by comparing said wafer position to a nominal wafer position;
• detecting a condition in which a wafer disposed on said wafer transport robot is displaced by more than a predetermined correctable displacement amount;
• adjusting a destination coordinate of said wafer transport robot in accordance with said wafer offset value;
• and
• suspending operation of the wafer processing system upon detecting that said wafer is displaced by more than said predetermined correctable displacement amount.

A method of positioning a wafer within a wafer processing system comprising the steps of:

• transporting a wafer into a chamber with a wafer transport robot so that said wafer is transported past a first wafer position sensor array;
• detecting a wafer center position as said wafer passes through a first wafer detection position defined by said first wafer position sensor array;
• transporting said wafer within said chamber so that said wafer is transported past a second wafer position sensor array;
• detecting a wafer position as said wafer passes through a second wafer detection position defined by said second wafer position sensor array;
• calculating a wafer offset value by comparing said wafer position to a nominal wafer position;
• and
• adjusting a destination coordinate of said wafer transport robot in accordance with said wafer offset value.

A method of positioning a wafer comprising the steps of:

• transporting a wafer within a chamber using a wafer transport robot so that said wafer is transported past at least one wafer detection position;
• directing an optical beam from a position external to a wafer transport chamber so that said optical beam propagates in a direction disposed away from a normal to a surface of said wafer during a wafer transport operation;
• reflecting said optical beam from a reflector within said chamber to form a reflected optical beam;
• detecting the intensity of said reflected optical beam at a detector position external to said chamber;
• detecting a wafer position as an edge of said wafer passes through said optical beam;
• calculating a wafer offset value by comparing said wafer position to a nominal wafer position;
• adjusting a destination coordinate of said wafer transport robot in accordance with said wafer offset value.