Laser-based method and system for memory link processing with picosecond lasers

Abstract

A laser-based method of removing a target link structure of a circuit fabricated on a substrate includes generating a pulsed laser output at a pre-determined wavelength less than an absorption edge of the substrate. The laser output includes at least one pulse having a pulse duration in the range of about 10 picoseconds to less than 1 nanosecond, the pulse duration being within a thermal laser processing range. The method also includes delivering and focusing the laser output onto the target link structure. The focused laser output has sufficient power density at a location within the target structure to reduce the reflectivity of the target structure and efficiently couple the focused laser output into the target structure to remove the link without damaging the substrate.

1 - 61 . (canceled)  
     
     
         62 . A method employing laser output pulses on the fly for removing target material associated with electrically conductive links, said target material including a passivation material overlying said links, said links being positioned between respective pairs of electrically conductive contacts in a circuit fabricated on a substrate, said links defining a link width, wherein the link may have a passivation layer neighboring the link that is susceptible to damage from the laser output pulses, said method comprising: 
 generating, from a laser, a first set of at least one laser output pulse during a first time interval, each of the laser output pulses of the set having a pulse duration ranging from several picoseconds to about 10 nanoseconds;    directing, in response to beam positioning data, the first set to impinge a first region of the overlying passivation layer that is spatially aligned with a first electrically conductive link, and at least one of the laser output pulses of the first set characterized by an energy distribution that is sufficient to remove the first region of the overlying passivation layer and expose the first electrically conductive link but insufficient to sever the first link or damage the neighboring passivation material;    generating, from the laser, a second set of at least one laser output pulse during a first time interval, each of the laser output pulses of the set having a pulse duration ranging from several picoseconds to about 10 nanoseconds;    directing, in response to beam positioning data, the second set to impinge a second region of the overlying passivation layer that is different from the first region and that is spatially aligned with a second electrically conductive link at a second location, and at least one of the laser output pulses of the second set characterized by an energy distribution that is sufficient to remove the second region of the overlying passivation layer and expose the second electrically conductive link but insufficient to sever the second electrically conductive link or damage the neighboring passivation material.    
     
     
         63 . The method of  claim 62 , wherein the first and second sets each consist of a single laser output pulse.  
     
     
         64 . The method of  claim 62 , in which the laser output pulses have a spot size that is smaller than 4 microns, but larger than the widths of the first or second links.  
     
     
         65 . The method of  claim 62 , in which the overlying passivation layer comprises SiO 2 .  
     
     
         66 . The method of  claim 65 , in which the overlying passivation layer is covered by a protective coating.  
     
     
         67 . The method of  claim 62 , in which the electrically conductive links comprise metal, polysilicide, or polysilicon.  
     
     
         68 . The method of  claim 62 , in which the neighboring passivation layer comprises SiO 2 .  
     
     
         69 . The method of  claim 62 , wherein the laser output pulses are generated by a pumped, Q-switched, solid state laser.