Method and system for precisely positioning a waist of a material-processing laser beam to process microstructures within a laser-processing site
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Abstract
A high-speed method and system for precisely positioning a waist of a material-processing laser beam to dynamically compensate for local variations in height of microstructures located on a plurality of objects spaced apart within a laser-processing site are provided. In the preferred embodiment, the microstructures are a plurality of conductive lines formed on a plurality of memory dice of a semiconductor wafer. The system includes a focusing lens subsystem for focusing a laser beam along an optical axis substantially orthogonal to a plane, an x-y stage for moving the wafer in the plane, and a first air bearing sled for moving the focusing lens subsystem along the optical axis.
90 Citations
45 Claims
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1-28. -28. (canceled)
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29. A method of precisely positioning a waist of a material-processing laser beam to dynamically-compensate for local variations in height of conductive links of a semiconductive memory located on a plurality of dies formed on a wafer and spaced apart within a laser-processing site, the laser beam having a spot diameter, W(z), variable along an optical axis, and a minimum spot diameter, Wo, at a beam waist location, the method comprising:
controllably positioning the waist of the laser beam along the optical axis to dynamically adjust the beam waist location between first and second links to be processed within the site so that;
a spot diameter, W(z), at a processing location is no more than about 5% greater than a minimum beam waist diameter over a total distance of about 1.5 microns or finer along the axis, and at a rate fast enough so that throughput is not substantially effected by the step of controllably positioning.- View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. A method for precisely positioning a waist of a material-processing laser beam to dynamically compensate for local variations in height of spaced apart conductive links of a semiconductive memory within a laser-processing site, the links lying on a surface which is substantially orthogonal to an optical axis, the method comprising:
controllably positioning the waist of the laser beam along the optical axis to dynamically adjust the beam waist location between first and second links to be processed within the site so that;
a spot diameter W(z) at a processing location is no more than about 5% greater than the minimum beam waist diameter over a total distance of about 1.5 microns or finer along the axis and at a rate fast enough so that throughput is not substantially effected by the step of controllably positioning.
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45. A method of laser processing of conductive links of a semiconductive memory, the method comprising:
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planning a trajectory to position a laser beam waist relative to the links to be processed; and
controllably positioning the beam waist along an optical axis based on the trajectory to dynamically adjust the beam waist location between first and second links to be processed so that;
a spot diameter, W(z), at a processing location is no more than about 5% greater than a minimum beam waist diameter over a total distance of about 1.5 microns or finer along the axis and at a rate fast enough so that throughput is not substantially effected by the step of controllably positioning.
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Specification