Apparatuses and methods for irradiating a substrate to avoid substrate edge damage

Abstract

Apparatuses and methods are provided for processing a substrate having an upper surface that includes a central region, a peripheral region, and an edge adjacent to the peripheral region. An image having an intensity sufficient to effect thermal processing of the substrate is scanned across the upper surface of the substrate. The image scanning geometry allows processing the central region of the substrate at a substantially uniform temperature without damaging the outer edge. In some instances, the image may be formed from a beam traveling over at least a portion of the central region so that no portion thereof directly illuminates any portion of the edge when the image is scanned across the periphery region. The substrate may be rotated 180° or the beam direction may be switched after part of the scanning operation has been completed.

1 . An apparatus for processing a substrate having an upper surface that includes a central region, a peripheral region, and an edge adjacent to the peripheral region and perpendicular to the upper surface, said apparatus comprising:
 a radiation source adapted to emit radiation;   an optical system adapted to receive the emitted radiation and create therefrom a beam that forms an image that is incident the upper surface of the substrate at an incident angle greater than 45°;   a stage adapted to support the substrate; and   a controller operably coupled to the radiation source and the stage, wherein the controller is programmed to provide relative movement between the stage and the beam to scan the image across the substrate surface in manner effective to process the substrate over at least the central region at a substantially uniform temperature without overheating the edge to a temperature that damages the edge.   
     
     
         2 . The apparatus of  claim 1 , further comprising a substrate supported by the stage, wherein the incident angle between the beam and the upper surface of substrate is at or near the Brewster angle. 
     
     
         3 . The apparatus of  claim 2 , wherein the substrate comprises Si. 
     
     
         4 . The apparatus of  claim 2 , wherein the edge is curved. 
     
     
         5 . The apparatus of  claim 2 , wherein the stage is movable. 
     
     
         6 . The apparatus of  claim 5 , wherein the stage is rotably movable by at least 180°. 
     
     
         7 . The apparatus of  claim 2 , wherein the controller is programmed to move the stage in a manner effective to ensure that no portion of the image directly illuminates any portion of the edge. 
     
     
         8 . The apparatus of  claim 7 , wherein the controller is programmed to orient the stage such that the substrate is rotated about an axis normal to the upper surface thereof. 
     
     
         9 . The apparatus of  claim 8 , wherein the controller is programmed to ensure that the image is scanned across the peripheral region of the surface. 
     
     
         10 . The apparatus of  claim 2 , wherein the controller is programmed to ensure that substantially all of the upper surface of the substrate is thermally processed. 
     
     
         11 . A method for processing a substrate having an upper surface that includes a central region, a peripheral region, and an edge adjacent to the peripheral region and perpendicular to the upper surface, said method comprising the steps of:
 (a) forming an image from a radiation beam that is incident to the upper surface of the substrate at an incident angle greater than 45°; and   (b) scanning the image across the substrate in a manner effective to process at least the central region of the substrate surface at a substantially uniform temperature without heating the edge to a temperature that damages the edge.   
     
     
         12 . The method of  claim 11 , wherein step (b) is carried out in a manner effective to ensure that no portion of the image directly illuminates any portion of the edge. 
     
     
         13 . The method of  claim 11 , further comprising the step of:
 (c) rotating the substrate about an axis normal to the upper surface thereof.   
     
     
         14 . The method of  claim 13 , wherein step (c) is carried out after a substantial portion of the upper surface of the substrate is thermally processed. 
     
     
         15 . The method of  claim 13 , wherein step (c) is carried out while step (b) is carried out. 
     
     
         16 . The method of  claim 11 , wherein step (b) scans the image across substantially all of the upper surface of the substrate. 
     
     
         17 . A method for processing a substrate having an upper surface divided into first and second regions and an edge adjacent to the upper surface, said method comprising the steps of:
 (a) forming an image on the first region from a radiation beam that first travels over the second region and is then incident the upper surface of the substrate at an incident angle;   (b) scanning the image across the first region;   (c) orienting the substrate and/or the beam such that the relative positions of the first and the second regions are transposed relative to the beam; and   (d) scanning the image across the second region,   wherein steps (b) and (d) are carried out in a manner effective to process the substrate at a substantially uniform temperature without heating the edge to a temperature that damages the edge.   
     
     
         18 . The method of  claim 17 , wherein the incident angle is greater than 45° 
     
     
         19 . The method of  claim 17 , wherein the incident angle is about 75°. 
     
     
         20 . The method of  claim 17 , wherein steps (b) and (d) scan the image across substantially all of the upper surface of the substrate.