Wafer orientation system

Apparatus for programmably orienting a semiconductor wafer in an ion implantation system so as to limit channeling or to control the depth of penetration of impinging ions. The apparatus is associated with a processing chamber door and includes a rotatable vacuum chuck for engaging the wafer and a motor for rotating the vacuum chuck and the wafer through a preselected angular displacement. The apparatus further includes a programmable control assembly operative to deenergize the motor upon sensing rotation of the vacuum chuck through the preselected angular displacement. The wafer orientation apparatus is typically utilized in a system for the vertical transfer of wafers between a cassette and a processing chamber.

What is claimed is:

1. Apparatus for positioning a generally circular wafer in a wafer processing chamber, said apparatus comprising:

wafer handling means associated with an entrance to said wafer processing chamber for receiving said wafer and moving said wafer into said processing chamber, including a processing chamber door movable between an open position in which said wafer is received and a sealed position in which said wafer is sealed into said wafer processing chamber and means for moving said chamber door between said open position and said sealed position;

means associated with said wafer handling means for engaging said wafer and rotating same through a programmable, preselected angular displacement about an axis generally perpendicular to said wafer and centrally located thereon, including a rotatable vacuum chuck extending from the inside surface of said chamber door for receiving said wafer when said chamber door is in said open position and means for rotating said vacuum chuck and said wafer through said preselected angular displacement; and

means for delivering said wafer to said wafer handling means, whereby the orientation of said wafer about said axis during processing is controlled.

2. Apparatus for positioning a generally circular wafer in a wafer processing chamber, said apparatus comprising:

wafer handling means associated with an entrance to said wafer processing chamber for receiving said wafer and moving said wafer into said processing chamber, including

a processing chamber door movable between an open position in which said wafer is received and a sealed position in which said wafer is sealed into said wafer processing chamber, said chamber door including a platen with a wafer-receiving surface against which said wafer is held during processing, said means for engaging said wafer and rotating same being associated with said wafer-receiving surface and

means for moving said chamber door between said open position and said sealed position;

means associated with said wafer handling means for engaging said wafer and rotating same through a programmable, preselected angular displacement about an axis generally perpendicular to said wafer and centrally located thereon, including

a rotatable vacuum chuck extending outwardly from said wafer-receiving surface to a wafer-receiving position in which said wafer is received and rotated, and retractable into said platen to a retracted position in which said wafer is held against said wafer-receiving surface and processed,

means for rotating said vacuum chuck and said wafer through said preselected angular displacement, and

means for moving said vacuum chuck between said wafer-receiving position and said retracted position; and

means for delivering said wafer to said wafer handling means, whereby the orientation of said wafer about said axis during processing is controlled.

3. The apparatus as defined in claim 2 wherein said means for rotating said vacuum chuck and said wafer includes

a motor for rotating said vacuum chuck and

programmable control means for sensing that said vacuum chuck has been rotated through said preselected angular displacement and for thereupon deenergizing said motor.

4. The apparatus as defined in claim 3 wherein said programmable control means includes

a shaft which rotates with said vacuum chuck, said shaft including a projection located at a prescribed angular position thereon and

sensing means which is programmed by angular displacement from said projection by a preselected amount, said sensing means being operative to sense rotation of said shaft by said preselected amount by sensing said projection and being further operative to then deenergize said motor.

5. The apparatus as defined in claim 2 wherein said means for rotating said vacuum chuck and said wafer includes

a motor for rotating said vacuum chuck and

means for energizing said motor for a predetermined time corresponding to the rotation of said vacuum chuck through said preselected angular displacement.

6. In a system for the automated transfer of generally circular wafers, one at a time, between a cassette holding a plurality of wafers and a wafer processing chamber, apparatus for providing each of the wafers with any preselected orientation, said apparatus comprising:

wafer handling means associated with an entrance to said wafer processing chamber for receiving a wafer and moving said wafer into said processing chamber, said wafer handling means including means for engaging said wafer and rotating same through a programmable, preselected angular displacement about an axis generally perpendicular to said wafer and centrally located thereon, said wafer handling means including

a processing chamber door movable between an open position in which said wafer is received and a sealed position in which said wafer is sealed into said wafer processing chamber,

a rotatable vacuum chuck extending from the inside surface of said chamber door for receiving said wafer when said chamber door is in said open position,

means for rotating said vacuum chuck and said wafer through said preselected angular displacement, and

means for moving said chamber door between said open position and said sealed position;

transfer means for transporting said wafer between said cassette and said wafer handling means;

cassette conveyor means for positioning said cassette relative to said transfer means; and

means for prealigning a guide flat on each of said plurality of wafers in said cassette.

7. In a system for the automated transfer of generally circular wafers, one at a time, between a cassette holding a plurality of wafers and a wafer processing chamber, apparatus for providing each of the wafers with any preselected orientation, said apparatus comprising:

wafer handling means associated with an entrance to said wafer processing chamber for receiving a wafer and moving said wafer into said processing chamber, including

a processing chamber door movable between an open position in which said wafer is received and a sealed position in which said wafer is sealed into said wafer processing chamber, said chamber door including a platen with a wafer-receiving surface against which said wafer is held during processing,

means for moving said chamber door between said open position and said sealed position and

means for engaging said wafer and rotating same through a programmable, preselected angular displacement about an axis generally perpendicular to said wafer and centrally located thereon, including a rotatable vacuum chuck extendable outwardly from said wafer-receiving surface to a wafer-receiving position in which said wafer is received and rotated, and retractable into said chamber door to a retracted position in which said wafer is held against said wafer-receiving surface and processed, means for rotating said vacuum chuck and said wafer through said preselected angular displacement, and means for moving said vacuum chuck between said wafer-receiving position and said retracted position;

transfer means for transporting said wafer between said cassette and said wafer handling means;

cassette conveyor means for positioning said cassette relative to said transfer means; and

means for prealigning a guide flat on each of said plurality of wafers in said cassette.

8. The apparatus as defined in claim 7 wherein said means for rotating said vacuum chuck and said wafer includes

a motor for rotating said vacuum chuck and

programmable control means for sensing that said vacuum chuck has been rotated through said preselected angular displacement and for thereupon deenergizing said motor.

9. The apparatus as defined in claim 8 wherein said programmable control means includes

a shaft which rotates with said vacuum chuck, said shaft including a projection located at a prescribed angular position thereon and

sensing means which is programmed by angular displacement from said projection by a preselected amount, said sensing means being operative to sense rotation of said shaft by said preselected amount by sensing said projection and being further operative to then deenergize said motor.

10. The apparatus as defined in claim 7 wherein said means for prealigning said guide flat on each of said plurality of wafers includes a roller associated with said cassette conveyor means and positioned so as to contact the edges of said plurality of wafers, said roller being operative when rotated, to rotate each of said plurality of wafers until said guide flat is positioned tangent to said roller.

11. The apparatus as defined in claim 10 wherein said roller is positioned below said plurality of wafers and wherein said means for prealigning said guide flat on each of said plurality of wafers further includes an element with a flat surface positioned below said plurality of wafers and movable, after operation of said roller, upward into contact with said guide flats of said plurality of wafers whereby said plurality of wafers is accurately prealigned.

12. The apparatus as defined in claim 11 wherein said transfer means includes a vertically movable elevator blade having an arcuate leading edge provided with a groove adapted to engage edgewise a wafer in said cassette from below and raise the wafer to said wafer handling means.

13. Apparatus for positioning a wafer having at least one orientation flat in a processing position with a prescribed orientation comprising:

wafer handling means associated with said processing position for receiving said wafer and moving said wafer into said processing position, including programmable orientation means for rotating said wafer through a programmable, preselected angular displacement relative to an initial orientation, about an axis generally perpendicular to said wafer and centrally located thereon, said wafer handling means comprising

a door of a processing chamber movable between an open position in which said wafer is received and a sealed position in which said wafer is sealed into said wafer processing chamber,

a rotatable vacuum chuck extending from the inside surface of said chamber door for receiving said wafer when said chamber door is in said open position,

means for rotating said vacuum chuck and said wafer through said preselected angular displacement, and

means for moving said chamber door between said open position and said sealed position; and

means for delivering said wafer to said wafer handling means with said initial orientation of said flat.

14. The apparatus as defined in claim 13 wherein said means for rotating said vacuum chuck and said wafer includes

a motor for rotating said vacuum chuck and

programmable control means for sensing that said vacuum chuck has been rotated through said preselected angular displacement and for thereupon deenergizing said motor.

15. The apparatus as defined in claim 14 wherein said programmable control means includes

a shaft which rotates with said vacuum chuck, said shaft including a projection located at a prescribed angular position thereon and

sensing means which is programmed by angular displacement from said projection by a preselected amount, said sensing means being operative to sense rotation of said shaft by said preselected amount by sensing said projection and being further operative to then deenergize said motor.

16. The apparatus as defined in claim 15 wherein said processing chamber is an ion implantation chamber and said programmable orientation means is operative to provide a preselected crystallographic orientation between said wafer and an ion beam.