Method for the bonding of disk-shaped substrates and apparatus for carrying out the method

Abstract

A first substrate ( 11 a ) is positioned on a support surface ( 7 ) in a vacuum chamber with an upward-facing first bonding surface ( 12 a ) spin-coated with adhesive while a second substrate ( 11 b ) is held with downward-facing second bonding surface ( 12 b ) to a cover ( 3 ) by suction. While the vacuum chamber is being evacuated to a pressure of between 0.1 mbar and 2 mbar, a support pin ( 9 ) is extended through central openings ( 14 a, 14 b ) of the substrates ( 11 a, 11 b ) and then retracted with the second substrate ( 11 b ) released from the cover ( 3 ) and carried by radially extended balls ( 10 ). The support pin ( 9 ) is lowered to a position where the balls ( 10 ), acting against the first bonding surface ( 12 a ), deform the first substrate ( 11 a ). The first bonding surface ( 12 a ) being therefore slightly concave, the first and second bonding surfaces ( 12 a, 12 b ) only touch close to their circumferences. Retraction of the balls ( 10 ) causes a spreading of the contact area radially inwards to cover the first and second bonding surfaces ( 12 a, 12 b ) without entrapment of non-bonded areas. The substrates ( 11 a, 11 b ) are then lifted by the support pin ( 9 ) with again extended balls ( 10 ) and pressed against the cover ( 3 ) and the vacuum chamber is aired.

1 . An apparatus for carrying out a method of bonding disk-shaped substrates comprising an essentially plane disk-shaped first substrate with a central opening and with a first bonding surface and a back surface opposite the first bonding surface, and an essentially plane disk-shaped second substrate with a central opening and with a second bonding surface to be bonded to the first bonding surface by a layer of adhesive, the apparatus comprising a vacuum chamber accommodating: 
 support means for supporting the first substrate, the support means being structured as a circumferential mechanical means for acting on the first substrate at positions offset towards the outer edge of the said substrate from its central opening,    a holding device for holding the second substrate in a position opposite the first substrate in a position opposite the first substrate with the second bonding surface facing the first bonding surface,    a support pin extendable through the central openings of the first substrate and the second substrate, with radially extendable and retractable central mechanical means for acting on the edge of the central opening of the first substrate or on the first bonding surface in the vicinity of the central opening.    
     
     
         2 . The apparatus of  claim 1 , wherein the vacuum chamber comprises a base plate carrying the support means and the support pin and a cover carrying the holding device.  
     
     
         3 . The apparatus of  claim 1 , wherein the central mechanical means comprise mechanical stop means for acting against the first bonding surface and the circumferential mechanical means comprise mechanical stop means for acting on the back surface of the first substrate.  
     
     
         4 . The apparatus of  claim 1 , wherein the support means is suitable for holding the first substrate in a position where the first bonding surface lies in an essentially horizontal first plane and the holding device is suitable for holding the second substrate in a position where the second bonding surface lies in an essentially horizontal second plane above the first plane.  
     
     
         5 . The apparatus of  claim 4 , wherein the first plane and the second plane are parallel.  
     
     
         6 . The apparatus of  claim 4 , wherein the first plane is slightly tilted with respect to the second plane.  
     
     
         7 . The apparatus of  claim 6 , wherein the angle between the first plane and the second plane is between 1° and 3°.  
     
     
         8 . The apparatus of  claim 1 , wherein the holding device is a suction holding device.