Methods for angled ion implantation of semiconductor devices

Abstract

This disclosure concerns methods for ion implantation of semiconductor devices such as VCSELs. In on example of such a method, a surface of the semiconductor structure is disposed at a predetermined orientation. The semiconductor structure is then rotated at a predetermined speed. An ion beam of characteristic flux is generated and directed at the surface of the semiconductor structure so that the ion beam is incident on the surface at an incident flux angle. Because the ion beam is incident on the surface at a defined angle, an implant region having an approximately wedge shaped cross-section is formed in the semiconductor device.

1 . A method for implanting a semiconductor structure, the method comprising: 
 disposing a surface of the semiconductor structure at a predetermined orientation;    rotating the semiconductor structure;    producing at least one ion beam having a characteristic flux; and    directing the at least one ion beam at the surface of the semiconductor structure so that the at least one ion beam is incident on the surface at an incident flux angle.    
   
   
       2 . The method as recited in  claim 1 , wherein disposing the surface of the semiconductor structure at a predetermined orientation comprises tilting the surface of the semiconductor structure relative to a predetermined direction along which the at least one ion beam is directed.  
   
   
       3 . The method as recited in  claim 1 , wherein the at least one ion beam is directed substantially along a predetermined direction that is tilted relative to the surface of the semiconductor structure such that the incident flux angle comprises an angle of tilt of the predetermined direction.  
   
   
       4 . The method as recited in  claim 1 , wherein producing the at least one ion beam comprises producing at least one ion beam having a predetermined implant energy.  
   
   
       5 . The method as recited in  claim 1 , wherein producing the at least one ion beam comprises producing a plurality of ion beams, each ion beam having a different implant energy level, flux and dose.  
   
   
       6 . The method as recited in  claim 1 , wherein a rotational speed of the semiconductor structure is substantially constant.  
   
   
       7 . The method as recited in  claim 1 , wherein the incident flux angle is controlled magnetically.  
   
   
       8 . The method as recited in  claim 1 , wherein the incident flux angle is controlled by adjusting a tilt angle of the surface of the semiconductor structure.  
   
   
       9 . The method as recited in  claim 1 , further comprising adjusting one or more of the following to achieve a desired implantation profile in the semiconductor structure: a tilt angle of the surface of the semiconductor structure; the incident flux angle; ion implant energy; and, dose.  
   
   
       10 . The method as recited in  claim 1 , wherein the semiconductor structure comprises a semiconductor wafer that includes a semiconductor device, and incidence of the ion beam on the surface of the semiconductor structure facilitates production of one of: an ion implant in the semiconductor device; and, an ion implant adjacent the semiconductor device.  
   
   
       11 . A method for implanting a semiconductor device, the method comprising: 
 disposing a surface of a vertical cavity surface emitting laser (VCSEL) structure at a predetermined orientation;    rotating the surface of the VCSEL structure;    producing at least one ion beam having a characteristic flux; and    directing the at least one ion beam at the surface of the VCSEL structure so that the at least one ion beam is incident on the surface at an incident flux angle.    
   
   
       12 . The method as recited in  claim 11 , wherein disposing the surface of the VCSEL structure at a predetermined orientation comprises tilting the surface of the VCSEL structure relative to a predetermined direction along which the at least one ion beam is directed.  
   
   
       13 . The method as recited in  claim 11 , wherein producing the at least one ion beam comprises producing at least one ion beam having a predetermined implant energy.  
   
   
       14 . The method as recited in  claim 11 , wherein producing the at least one ion beam comprises producing a plurality of ion beams, each ion beam having a different implant energy level, flux and dose.  
   
   
       15 . The method as recited in  claim 14 , wherein respective incident flux angles of the ion beams are substantially the same.  
   
   
       16 . The method as recited in  claim 14 , wherein respective incident flux angles of the ion beams are different.  
   
   
       17 . The method as recited in  claim 11 , wherein a rotational speed of the VCSEL structure is substantially constant.  
   
   
       18 . The method as recited in  claim 11 , wherein the VCSEL structure includes a mesa, the at least one ion beam being directed to an area of the VCSEL structure located proximate the mesa.  
   
   
       19 . A method for producing an implanted semiconductor structure, the method comprising: 
 depositing an ion resistant mask material proximate a surface of a semiconductor wafer;    etching away a selected portion of the ion resistant mask material to produce an ion implantation mask;    disposing the surface of the semiconductor wafer at a predetermined orientation;    rotating the semiconductor wafer;    producing an ion beam having a characteristic flux; and    directing the ion beam at the surface of the semiconductor wafer so that the ion beam is incident on the surface at an incident flux angle    
   
   
       20 . The method as recited in  claim 19 , wherein the ion resistant mask material is lithographically defined and etched.  
   
   
       21 . The method as recited in  claim 19 , further comprising coating the semiconductor wafer with a planarizing material such that the ion resistant mask material is deposited on top of the planarizing material.  
   
   
       22 . The method as recited in  claim 21 , wherein the planarizing material comprises at least one of: BDB; polyimide; photo-resist; and, spin-on glass.  
   
   
       23 . A method for implanting a semiconductor device, the method comprising: 
 disposing a surface of a vertical cavity surface emitting laser (VCSEL) structure at a predetermined orientation;    rotating the surface of the VCSEL structure;    producing a first ion beam;    directing the first ion beam at the surface of the VCSEL structure so that the first ion beam is incident on the surface at a first incident flux angle;    producing a second ion beam; and    directing the second ion beam at the surface of the VCSEL structure so that the second ion beam is incident on the surface at a second incident flux angle.    
   
   
       24 . The method as recited in  claim 23 , wherein the first ion beam has an ion implant energy that is less than an ion implant energy of the second ion beam.  
   
   
       25 . The method as recited in  claim 23 , wherein the first and second incident flux angles are different.  
   
   
       26 . The method as recited in  claim 23 , further comprising: 
 forming top and lower ion implantation masks on the VCSEL structure;    removing the top implantation mask after direction of the first ion beam at the surface of the VCSEL structure; and    removing the lower implantation mask after direction of the second ion beam at the surface of the VCSEL structure.    
   
   
       27 . The method as recited in  claim 26 , wherein the top and lower ion implantation masks are formed lithographically.  
   
   
       28 . The method as recited in  claim 26 , wherein the first incident flux angle is substantially the same as the second incident flux angle.