Substrate processing with reduced warpage and/or controlled strain

Abstract

Provided are systems and methods for processing the surface of substrates that scan a laser beam at one or more selected orientation angles. The orientation angle or angles may be selected to reduce substrate warpage. When the substrates are semiconductor wafers having microelectronic devices, the orientation angles may be selected to produce controlled strain and to improve electronic performance of the devices.

1 . A system for processing a surface of a substrate to produce a device, comprising:
 a radiation source adapted to emit a photonic beam suitable for processing the substrate surface;   a stage adapted to support and move the substrate translationally relative to the beam;   an alignment system to position the substrate on the stage at a selected orientation angle relative to a surface normal of the stage; and   a controller operably coupled to the radiation source, the stage, and the alignment system, wherein the controller is adapted to provide a first relative scanning motion between the stage and the beam to allow the beam to scan translationally over substantially the entire surface of the substrate along a first path at a first orientation angle followed by a second relative scanning motion between the stage and the beam to allow the beam to scan translationally over at least a portion of the surface of the substrate along a second path at a second orientation angle with said first and second orientation angles each selected to optimize performance characteristics of said device.   
     
     
         2 . The system of  claim 1 , wherein the radiation source includes a CO 2  laser. 
     
     
         3 . The system of  claim 2 , wherein the radiation source includes a relay adapted to direct the beam toward the surface substrate at an incidence angle of at least 45°. 
     
     
         4 . The system of  claim 3 , wherein the incidence angle is substantially identical to the Brewster's angle of the beam for the surface. 
     
     
         5 . The system of  claim 3 , wherein the relay is adapted to form an elongate image on the substrate surface. 
     
     
         6 . The system of  claim 5 , wherein the elongate image has a lengthwise axial directionality that traverses the relative translational scanning motion between the beam and the stage. 
     
     
         7 . The system of  claim 1 , wherein the controller is adapted to allow the beam to scan translationally over substantially the entire substrate surface at said second orientation angle. 
     
     
         8 . The system of  claim 1 , wherein the alignment system is adapted to alter the substrate from the first to the second orientation angle without removing the substrate from the stage. 
     
     
         9 . The system of  claim 1 , wherein the alignment system is adapted to remove the substrate from the stage to alter the position of the substrate from the first to the second orientation angle. 
     
     
         10 . The system of  claim 1 , wherein the first and second orientation angles differ by about 90°. 
     
     
         11 . A method for processing a surface of a substrate, comprising:
 (a) generating a photonic beam suitable for processing the substrate surface;   (b) scanning the beam translationally over the substrate surface along a first path at a first orientation angle; and   (c) scanning the beam translationally over the substrate surface along a second path at a second orientation angle.   
     
     
         12 . The method of  claim 11 , wherein the photonic beam illuminates no more than 5% of the substrate surface at one time. 
     
     
         13 . The method of  claim 11 , wherein the photonic beam is effective to heat an illuminated portion of the substrate surface at a rate of at least 1000° C. per second. 
     
     
         14 . The method of  claim 11 , wherein steps (b) and (c) is carried out to allow the beam to scan translationally over substantially the entire substrate surface at first and second orientation angles. 
     
     
         15 . The method of  claim 11 , wherein the first and second paths, when viewed from the first and second orientation angles, respectively, are substantially identical to each other. 
     
     
         16 . The method of  claim 15 , wherein each of the first and second paths include a plurality of parallel segments. 
     
     
         17 . The method of  claim 16 , wherein the parallel segments of each of the first and second paths are linear. 
     
     
         18 . The method of  claim 16 , wherein the parallel segments of each of the first and second paths are curved. 
     
     
         19 . The method of  claim 16 , wherein the parallel segments are spaced at a predetermined distance from each other such that the illuminated sections substrate along the parallel segments overlap. 
     
     
         20 . The method of  claim 19 , wherein the beam has an intensity profile and predetermined distance is selected according to the intensity profile. 
     
     
         21 . The method of  claim 20 , wherein the intensity profile has a peak intensity region and the predetermined distance is selected such that the peak intensity regions do not overlap. 
     
     
         22 . The method of  claim 11 , wherein steps (b) and (c) are performed at substantially identical scan rates. 
     
     
         23 . The method of  claim 11 , wherein one of steps (b) and (c) is carried out to allow the beam to scan translationally over substantially the entire substrate surface and the other of steps (b) and (c) is carried out to allow the beam to scan over only a selected portion of the substrate surface. 
     
     
         24 . A method for processing a substrate to produce a desired substrate surface contour, comprising:
 (a) providing a substrate having a surface having an initial surface contour profile;   (b) generating a photonic beam suitable for processing the substrate surface;   (c) scanning the beam translationally over the substrate surface along a first path at a first orientation angle, thereby converting the initial surface contour into intermediate surface contour; and   (d) scanning the beam translationally over the substrate surface along a second path at a second orientation angle, thereby converting the intermediate surface contour into the desired surface contour.   
     
     
         25 . A method for reshaping a substrate having a surface with a contour unsuitable for subsequent processing, comprising:
 (a) generating a photonic beam suitable for thermally processing the substrate surface; and   (b) scanning the beam translationally over the substrate surface along a selected path and a selected orientation angle to reshape the surface in a manner effective to convert the unsuitable surface contour into a contour suitable for subsequent processing.   
     
     
         26 . A method for thermally processing a semiconductor substrate having a microelectronic circuit on a surface thereof, comprising:
 (a) generating a photonic beam suitable for producing an elongate image suitable for thermally processing the substrate surface; and   (b) scanning the image translationally over the substrate surface at an orientation angle effective to produce a surface strain in a manner the enhances carrier mobility in the microelectronic circuit relative to carrier mobility of the circuit without the surface strain.   
     
     
         27 . The method of  claim 26 , wherein the microelectronic circuit comprises a PMOS transistor. 
     
     
         28 . The method of  claim 26 , wherein the microelectronic circuit comprises a NMOS transistor. 
     
     
         29 . The system of  claim 1  wherein said stage is rotatable about said surface normal to alter the position of the substrate from the first to the second orientation angle. 
     
     
         30 . The system of  claim 1  wherein said first and second orientation angles are selected so warpage of the substrate produced when the substrate surface is scanned at the first orientation angle is reduced by scanning of the substrate surface at the second orientation angle to optimize characteristics of said device. 
     
     
         31 . The system of  claim 1  wherein a shape and orientation of an image created on the surface of the substrate by the photonic beam is selected based on a crystallographic orientation of the substrate to reduce warpage of the substrate. 
     
     
         32 . The system of  claim 31  wherein when said device being formed on said substrate is a transistor with a particular channel orientation, an orientation angle of said image from said photonic beam relative to the channel orientation is selectable to maximize performance of said transistor when completed.