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 system for removing target material associated with electrically conductive links positioned between respective pairs of electrically conductive contacts in a circuit fabricated on a substrate, said links defining a link width, said system comprising: 
 a pumped, mode locked laser for generating laser output pulses having a pulse width ranging from several picoseconds to about 10 nanoseconds;    an optical switch configured to select processing pulses for focusing onto a spot on the substrate, wherein each of the output pulses are characterized by a laser spot size when focused on the link location that is larger than the link width, wherein said pulse energy and power characteristics are such that damage to material underlying the link during link processing is avoided, and insufficient to sever the link;    a beam positioning system imparting relative movement of a laser spot position over the substrate in response to processing control signals representing one or more locations of electrically conductive links; and    a laser system controller for coordinating the optical switch and the beam positioning system such that the relative movement is substantially continuous and the laser output pulses strike the overlying passivation layer and encompass the link width, the output pulses removing the overlying passivation material associated with the link without causing undesirable damage to material underlying the link.