Semiconductor structure processing using multiple laser beam spots overlapping lengthwise on a structure

Abstract

Methods and systems use laser pulses to process a selected structure on or within a semiconductor substrate. The structure has a surface, a width, and a length. The laser pulses propagate along axes that move along a scan beam path relative to the substrate as the laser pulses process the selected structure. The method simultaneously generates on the selected structure first and second laser beam pulses that propagate along respective first and second laser beam axes intersecting the selected structure at distinct first and second locations. The first and second laser beam pulses impinge on the surface of the selected structure respective first and second beam spots. Each beam spot encompasses at least the width of the selected link. The first and second beam spots are spatially offset from one another along the length of the selected structure to define an overlapping region covered by both the first and the second beam spots and a total region covered by one or both of the first and second beam spots. The total region is larger than the first beam spot and also larger than the second beam spot. The method sets respective first and second energy values of the first and second laser beam pulses to cause complete depthwise processing of the selected structure across the width of the structure in at least a portion of the total region.

1 . A method for using laser pulses to process a selected structure on or within a semiconductor substrate, the structure having a surface, a width, and a length, and the laser pulses propagating along axes that move along a scan beam path relative to the substrate as the laser pulses irradiate the selected structure, the method comprising:
 simultaneously generating on the selected structure first and second laser beam pulses that propagate along respective first and second laser beam axes intersecting the selected structure at distinct first and second locations, the first and second laser beam pulses impinging on the surface of the selected structure respective first and second beam spots, each beam spot encompassing at least the width of the selected structure, the first and second beam spots being spatially offset from one another along the length of the selected structure to define an overlapping region covered by both the first and the second beam spots and a total region covered by one or both of the first and second beam spots, wherein the total region is larger than the first beam spot and also larger than the second beam spot; and   setting respective first and second energy values of the first and second laser beam pulses to cause complete depthwise processing of the selected structure across its width in at least a portion of the total region.   
     
     
         2 . The method of  claim 1 , further comprising:
 establishing a time delay between the first and second laser beam pulses to cause the complete depthwise processing of the selected structure on-the-fly as the first and second laser beam axes move along the scan beam path.   
     
     
         3 . The method of  claim 2 , wherein the time delay is sufficiently large to avoid a deleterious concentration of absorbed energy in the vicinity of the selected structure. 
     
     
         4 . The method of  claim 2 , wherein the first and second beam spots are spatially offset from one another in a direction perpendicular to the lengthwise direction of the selected structure 
     
     
         5 . The method of  claim 1 , in which the first and second laser energy beam pulses have approximately equal energy. 
     
     
         6 . The method of  claim 1 , in which the first and second beam spots have approximately equal laser beam spot size. 
     
     
         7 . The method of  claim 6 , in which the spatial offset of the first and second beam spots is less than about 50% of the laser beam spot size. 
     
     
         8 . The method of  claim 1 , in which the second laser beam pulse has at least one optical property different from the first laser beam pulse. 
     
     
         9 . The method of  claim 1 , in which the selected structure is an electrically conductive link, and the processing is for the purpose of severing the link. 
     
     
         10 . The method of  claim 1 , wherein the generating step comprises:
 generating the first and second laser beams from two respective lasers.   
     
     
         11 . The method of  claim 1 , wherein the generating step comprises:
 generating a single laser beam from a single laser; and   splitting the single laser beam to form the first and second laser beams.   
     
     
         12 . The method of  claim 11 , in which the splitting step comprises:
 diffracting the single laser beam into two beams separated by a predetermined angle, the two beams passing through one or more optical components to form the first and second beam spots on the selected structure along its length, thereby achieving the spatial offset of the first and second beam spots.   
     
     
         13 . The method of  claim 1 , wherein the generating step is commenced based upon a trigger signal. 
     
     
         14 . The method of  claim 13 , wherein the trigger signal is generated based upon a timing signal. 
     
     
         15 . The method of  claim 13 , wherein the trigger signal is generated based upon a comparison of a desired target location and one or more of the first and second locations. 
     
     
         16 . A semiconductor substrate processed according to the method of  claim 1 .