Abstract: Systems and methods for stabilizing a CO2 laser are disclosed. The system includes a detector unit for measuring the power in a select portion of the output beam. The detector unit generates an electrical signal corresponding to the measured power. The modulation frequency of the signal used to modulate the relatively high-frequency radio-frequency (RF) pump signal is filtered from the electrical signal. The filtered electrical signal is then-compared to a desired value for the output power in the output beam. Based on the comparison, a modulation control signal for modulating the RF pump signal is formed. The modulation control signal has a varying duty cycle that varies the amount of laser pump power to reduce or eliminate the measured variations in the output beam power. The result is an output beam power that remains stable over time.

Abstract: Systems and methods for stabilizing a CO2 laser are disclosed. The system includes a detector unit for measuring the power in a select portion of the output beam. The detector unit generates an electrical signal corresponding to the measured power. The modulation frequency of the signal used to modulate the relatively high-frequency radio-frequency (RF) pump signal is filtered from the electrical signal. The filtered electrical signal is then compared to a desired value for the output power in the output beam. Based on the comparison, a modulation control signal for modulating the RF pump signal is formed. The modulation control signal has a varying duty cycle that varies the amount of laser pump power to reduce or eliminate the measured variations in the output beam power. The result is an output beam power that remains stable over time.

Abstract: Methods and apparatus for truncating an image formed with coherent radiation. The optical relay system is adapted to form a line image at the image plane. The image is truncated by a variable aperture at or near the aperture plane conjugate to the image plane, to block progressively increasing portions of an incident coherent radiation beam used to form the line image. An apodizing pupil filter having a maximum transmission or reflection in the center and a transmission or reflection profile that varies with direction corresponding to long direction of the line image is provided in the pupil plane. The apodization is designed to prevent hot-spots from forming in the truncated image and ensures a relatively smooth, flat intensity profile. Thus, one end or another of a coherent line image scanned over a substrate can be truncated during scanning without substantially changing the image intensity extending into the product area.

Abstract: Chuck methods and apparatus for supporting a semiconductor substrate and maintaining it at a substantially constant background temperature even when subject to a spatially and temporally varying thermal load. Chuck includes a thermal compensating heater module having a sealed chamber containing heater elements, a wick, and an alkali metal liquid/vapor. The chamber employs heat pipe principles to equalize temperature differences in the module. The spatially varying thermal load is quickly made uniform by thermal conductivity of the heater module. Heatsinking a constant amount of heat from the bottom of the heater module accommodates large temporal variations in the thermal heat load. Constant heat loss is preferably made to be at least as large as the maximum variation in the input heat load, less heat lost through radiation and convection, thus requiring a heat input through electrical heating elements. This allows for temperature control of the chuck, and hence the substrate.

Abstract: Systems and methods for stabilizing a CO2 laser are disclosed. The system includes a detector unit for measuring the power in a select portion of the output beam. The detector unit generates an electrical signal corresponding to the measured power. The modulation frequency of the signal used to modulate the relatively high-frequency radio-frequency (RF) pump signal is filtered from the electrical signal. The filtered electrical signal is then compared to a desired value for the output power in the output beam. Based on the comparison, a modulation control signal for modulating the RF pump signal is formed. The modulation control signal has a varying duty cycle that varies the amount of laser pump power to reduce or eliminate the measured variations in the output beam power. The result is an output beam power that remains stable over time.

Abstract: Methods and apparatus for truncating an image formed with coherent radiation. The optical relay system is adapted to form a line image at the image plane. The image is truncated by a variable aperture at or near the aperture plane conjugate to the image plane, to block progressively increasing portions of an incident coherent radiation beam used to form the line image. An apodizing pupil filter having a maximum transmission or reflection in the center and a transmission or reflection profile that varies with direction corresponding to long direction of the line image is provided in the pupil plane. The apodization is designed to prevent hot-spots from forming in the truncated image and ensures a relatively smooth, flat intensity profile. Thus, one end or another of a coherent line image scanned over a substrate can be truncated during scanning without substantially changing the image intensity extending into the product area.

Abstract: A chuck for supporting a wafer and maintaining a constant background temperature across the wafer during laser thermal processing (LTP) is disclosed. The chuck includes a heat sink and a thermal mass in the form of a heater module. The heater module is in thermal communication with the heat sink, but is physically separated therefrom by a thermal insulator layer. The thermal insulator maintains a substantially constant power loss at least equal to the maximum power delivered by the laser, less that lost by radiation and convection. A top plate is arranged atop the heater module, supports the wafer to be processed, and provides a contamination barrier. The heater module is coupled to a power supply that is adapted to provide varying amounts of power to the heater module to maintain the heater module at the constant background temperature even when the wafer experiences a spatially and temporally varying heat load from an LTP laser beam.

Abstract: A beamsplitter apparatus for use with high-power radiation is disclosed. The apparatus includes a thermally conductive frame with a central aperture. The frame holds a window in the central aperture at the window's periphery. The window includes a diamond substrate with an optional coating formed thereon. Because the substrate is diamond and the frame is thermally conductive, the window is less susceptible to thermal effects caused by absorption of the incident radiation by the window. Thus, the original flatness of the widow surfaces is preserved, and variations in its index of refraction will be minimal. The result is that high-power radiation beams reflected from and transmitted by the widow remain substantially undistorted.

Abstract: A beamsplitter apparatus for use with high-power radiation is disclosed. The apparatus includes a thermally conductive frame with a central aperture. The frame holds a window in the central aperture at the window's periphery. The window includes a diamond substrate with an optional coating formed thereon. Because the substrate is diamond and the frame is thermally conductive, the window is less susceptible to thermal effects caused by absorption of the incident radiation by the window. Thus, the original flatness of the widow surfaces is preserved, and variations in its index of refraction will be minimal. The result is that high-power radiation beams reflected from and transmitted by the widow remain substantially undistorted.