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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

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.

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What is claimed is: 1. A laser-based system for removing a target link structure of a circuit fabricated on a substrate without causing undesirable damage to the substrate, any dielectric layers between the target link structure and the substrate, or link structures adjacent the target link structu

What is claimed is: 1. A laser-based system for removing a target link structure of a circuit fabricated on a substrate without causing undesirable damage to the substrate, any dielectric layers between the target link structure and the substrate, or link structures adjacent the target link structure, the target link structure being in a set of link structures, at least some link structures in the set of link structures being separated by a pitch of less than 2 μm, the system comprising: means, including a seed laser, for generating a sequence of laser pulses at a repetition rate of greater than about 1 MHZ, the seed laser having a first predetermined wavelength; means for optically amplifying at least a portion of the sequence of laser pulses to obtain an amplified sequence of output pulses; means for controllably selecting at least a portion of the amplified sequence of output pulses based on at least one of position and velocity information to synchronize the target link structure with laser beam position during motion of the substrate relative to the laser beam, wherein the means for controllably selecting includes either an acousto-optic modulator or an electro-optic modulator; and means for delivering and focusing pulses of the amplified sequence of output pulses onto the target link structure during the relative motion, substantially all pulses of the amplified sequence of output pulses having a pulse duration greater than about 10 picoseconds and less than about 100 picoseconds, corresponding pulse power densities in the range of at least about 109 W/cm2 to less than about 1013 W/cm2 over a focused spot diameter of 1.5 microns or less at the target link structure, and a wavelength of about 1.2 microns or less. 2. The system of claim 1 wherein the means for generating includes a master oscillator and power amplifier (MOPA). 3. The system of claim 1 wherein temporal spacing between substantially all immediately adjacent pulses of the sequence of laser pulses is at least 5 nanoseconds, and wherein the means for controllably selecting reduces the repetition rate to within a range of about 20 KHz to 150 KHz. 4. The system of claim 1 wherein the modulator is a Mach-Zehnder modulator. 5. The system of claim 1 wherein the sequence of laser pulses includes at least one pulse having a pulse duration greater than about 1 nanosecond, and wherein the system further comprises a compressor or pulse slicer to compress or slice, respectively, the at least one nanosecond pulse to produce a pulse having a pulse duration less than about 100 ps. 6. The system of claim 5 wherein the seed laser is a q-switched microlaser or laser diode having a pulse duration of about one nanosecond. 7. The system of claim 5 wherein an output of the compressor or slicer is received by the means for optically amplifying. 8. The system of claim 1 wherein the seed laser is diode-pumped, solid-state laser. 9. The system of claim 8 wherein the diode-pumped, solid-state laser is a fiber laser oscillator. 10. The system of claim 1 wherein the seed laser is an active or passive mode-locked laser. 11. The system of claim 1 wherein the seed laser is a high-speed, semiconductor laser diode. 12. The system of claim 1 wherein the means for optically amplifying includes at least one fiber-optic amplifier. 13. The system of claim 12 wherein the fiber-optic amplifier has a gain of about 30 dB. 14. The system of claim 1 wherein the first predetermined wavelength is in a range of about 1.3 μm to about 1.55 μm, and further comprising a wavelength shifter to shift the laser wavelength of the amplified sequence of output pulses from the first predetermined wavelength to a near Infrared or visible wavelength. 15. The system of claim 1 wherein the means for generating includes a master oscillator and the means for optically amplifying includes a power amplifier (MOPA). 16. The system of claim 1, wherein the pulse width of substantially all of the pulses corresponds to a duration wherein a fluence threshold for target link structure removal is substantially proportional to the square root of the pulse width, whereby the target link structure is removed in a thermal manner. 17. The system of claim 1, wherein the at least one target link structure is covered by one or more overlying passivation layers, wherein the power density of one or more pulses creates a thermal shock to the one or more overlying passivation layers and removes the one or more overlying passivation layers and the at least one target link structure, the removal of the one or more overlying passivation layers and the at least one target link structure occurring as a result of both thermo-mechanical stress and ablation. 18. The system of claim 17, wherein the one or more overlying passivation layers are inorganic passivation layers having absorption edges in a range of ultraviolet wavelengths, and wherein the pulse power densities are less than about 1012 W/cm2. 19. The system of claim 1, wherein at least one pulse of the sequence is focused to a non-round spot to improve energy enclosure. 20. The system of claim 1, wherein the number of pulses and speed of the motion cause a dimension to exceed a predetermined tolerance, and wherein the system further comprises a solid state deflector for deflecting the pulses to direct the pulses to locations within the tolerance. 21. The system of claim 20, wherein the deflector is an acousto-optic device or an electro-optic device. 22. The system of claim 1 further comprising: a multi-frequency deflector to form a group of spatially split pulses from a single pulse and to selectively direct at least one of the spatially split pulses to a first target link structure, to a second target link structure, or to both the first and second target link structures. 23. The system of claim 1, wherein the seed laser includes multiple laser sources, and wherein the system further comprises means for optically combining outputs of the laser sources into a common optical path to generate the sequence of pulses. 24. The system of claim 23, wherein the laser sources are of different types, and at least one of the laser sources comprises a semiconductor laser diode. 25. The system of claim 1, wherein the sequence of pulses produces a heat affected zone having a dimension in a range of about 0.1 micron to about 0.85 microns. 26. The system of claim 1, wherein the focused spot diameter is less than about 1.0 micron. 27. The system of claim 1, wherein at least two immediately adjacent pulses of the sequence have a temporal spacing in the range of about 2 nanoseconds to about 10 nanoseconds, thereby corresponding to an effective repetition rate in the range of about 100 MHz to about 500 MHz and where the temporal spacing exceeds a time interval for dissipation of a vapor plasma plume produced by a previous laser pulse interaction with the at least one target link structure and the link structures adjacent the at least one target link structure. 28. The system of claim 1, wherein the temporal spacing between substantially all immediately adjacent pulses is about 5 nanoseconds or greater. 29. The system of claim 1, wherein exactly two pulses of the amplified sequence are delivered to the target link structure and each of the two pulses has an energy that is about 50-70% of the energy required to remove the target link structure with a single pulse. 30. The system of claim 1, wherein the pulse duration is within a thermal processing range wherein the pulse duration is longer than a characteristic pulse duration at which the relationship of fluence breakdown threshold versus laser pulse duration exhibits a rapid and distinct change in slope at the characteristic pulse duration 31. The system of claim 1, wherein focused pulses of the amplified sequence of pulses are positioned at the target link within a predetermined positioning tolerance and wherein focused pulses of the amplified sequence of pulses produce a heat affected zone (HAZ) substantially less than the positioning tolerance. 32. The system of claim 1, further comprising means for moving the substrate relative to focused pulses of the amplified sequence of pulses. 33. The system of claim 32, wherein the means for delivering and focusing includes at least one optical element for moving the substrate relative to focused pulses of the amplified sequence of pulses in a z direction and wherein the means for moving moves the substrate relative to focused pulses of the amplified sequence of pulses in two directions substantially orthogonal to the z direction. 34. The system of claim 1, wherein the amplified sequence of output pulses comprises two or more groups of pulses.