Spinner chuck

A vacuum chuck for spinning a wafer during processing, comprising:

• a wafer platform for supporting said wafer on a first surface;
• spindle means centrally attached to said wafer platform adapted to connect said wafer platform to a means for spinning said platform;
• channels in said first surface of said wafer platform adapted to provide a source of suction;
• a depressed region in said first susrface of said wafer platform located laterally exterior to said channels and adapted to receive an O-ring of a pre-determined thickness for sealing against said wafer;
• wherein said depressed region is wider and deeper than said pre-determined thickness;
• wherein said depressed region has a first sidewall portion adapted to moveably retain said O-ring so that, in the absence of said wafer, the upper surface of said O-ring protrudes above said first surface;
• wherein said depressed region has a second portion sloped away from said spindle means at a substantially constant angle with respect to said first surface and located below said first sidewall portion;
• and
• wherein said first sidewall portion has a toroidal-shape conforming to the interior radius of said O-ring and said second sloped portion has a conical-shape and wherein said first and second portions join tangentially.

A rotatable holder for wafer processing, comprising:

• a platform having a first surface adapted to receive said wafer;
• spindle means centrally coupled to said platform at a right angle thereto for rotating said first surface about the longitudinal axis of said spindle;
• retention means at the periphery of said first surface adapted to moveably retain an O-ring for sealing against said wafer and having a depth greater than the thickness of said O-ring;
• wherein said retention means comprises a recessed region located below said first surface and adapted to moveably retain said O-ring in a first position so that a first portion of said O-ring for contacting said wafer protrudes above said first surface;
• wherein said O-ring retention means comprises an extension portion, located beneath said recessed region and smoothly joined therewith, and sloping away from said first surface at an angle with respect to said first surface of not less than the angle of said recessed region measured with respect to said first surface in a plane perpendicular to said first surface where said recessed region intersects said extension region;
• and
• wherein said recessed region has a cross-section whose perimeter comprises a sector of a circle, wherein said sector of said circle has a center of curvature located beneath said first surface by a distance less than the radius of curvature of said circle, wherein said extension portion has a cross-section whose perimeter comprises a substantially straight line sloping away from said first surface at a predetermined substantially constant angle, and wherein said sector of said circle and said line intersect tangentially at a point located below said center of curvature.

A method for spinning a wafer comprising:

• providing a wafer chuck having a peripheral seal holding groove with a conical skirt below said groove;
• providing in said groove a moveable circular seal for contacting and sealing against said wafer and said wafer chuck, wherein a portion of said seal protrudes from a first surface of said chuck;
• placing a wafer on said seal above said first surface;
• applying a pressing force to said wafer in a direction toward said first surface;
• moving said seal, in contact with said wafer and said wafer chuck, downwards over said conical skirt without substantially crushing said seal while simultaneously radially stretching said seal to provide an opposing force for sealing and for automatically restoring said seal to its position prior to said applying step after spinning is stopped;
• and
• spinning said chuck and said wafer.

A method for mounting a fragile wafer on a chuck for processing, comprising:

• providing a chuck having a seal holding means including a conical skirt located below a first surface of said chuck, for retaining a moveable seal for contacting and sealing against said wafer and said chuck, wherein a portion of said seal protrudes from said first surface of said chuck and wherein said seal holding means and skirt together have a depth perpendicular to said surface exceeding the thickness of said seal;
• placing a wafer on said seal above said first surface;
• applying a pressing force to said wafer in a direction toward said first surfaqce;
• moving said seal away from said surface along said conical skirt, in contact with said wafer and said chuck, without substantially crushing said seal;
• and
• applying a centrifugal force to said moveable seal.

A method for holding wafers, comprising:

• providing a wafer chuck having a first surface containing a vacuum suction means, an elastic seal, and a retaining means for moveably retaining said elastic seal, wherein said retaining means has a depth greater than the thickness of said seal, a first portion for initially locating said seal adjacent said first surface, and a second portion adjacent said first portion for retracting said seal so as to be, except for irregularities in said wafer, substantially flush with said first surface;
• locating said elastic seal in said first portion of said retaining means so that it initially protrudes from said first surface by a predetermined distance;
• placing a wafer on the protruding surface of said elastic seal;
• applying vacuum suction to draw said wafer toward said first surface;
• and
• retracting said seal by moving said seal perpendicular to said first surface by a first amount not more than said pre-determined distance while at the same time radially stretching said seal by a second amount directly proportional to said first amount and spinning said chuck.

A rotatable holder for wafer processing, comprising:

• a platform having a first surface adapted to receive said wafer;
• spindle means centrally coupled to said platform at a right angle thereto for rotating said first surface about the longitudinal axis of said spindle;
• retention means at the periphery of said first surface adapted to moveably retain an O-ring for sealing against said wafer and having a depth greater than the thickness of said O-ring;
• wherein said retention means comprises a recessed region located below said first surface and adapted to moveably retain said O-ring in a first position so that a first portion of said O-ring for contacting said wafer protrudes above said first surface;
• and
• wherein said O-ring retention means comprises an extension portion for moveably receiving said O-ring, located beneath said recessed region and smoothly joined therewith, and sloping away from said first surface at a subtantially constant angle with respect to said first surface of not less than the angle of said recessed region measured with respect to said first surface in a plane perpendicular to said first surface where said recessed region intersects said extension region.

A vacuum chuck for retaining a wafer, comprising:

• a first surface of said chuck adapted to receive said wafer;
• suction means in said first surface for applying suction to said wafer to cause it to move toward said first surface;
• and
• retention means in said first surface for moveably retaining an O-ring for sealing against said wafer and said chuck while said O-ring slides or rolls away from said first surface in response to the motion of said wafer toward said first surface, said retention means having a first portion adjacent said first surface for initially locating said O-ring so that it partially protrudes from said first surface and a second portion below said first portion, joining smoothly therewith, and making an angle with respect to said first surface which does not decrease with increasing distance from said first surface.