Abstract: The present invention provides an apparatus and method to automatically focus an incident beam of monochromatic parallel planar light on a work piece, using a fringe plate and a vision detector. The work piece may have a perfect mirror surface, or have a non-reflective patterned surface. The incident light beam is focused on the work piece and then reflected through a fringe plate forming an interference pattern on the vision detector. The incident light beam is then scanned or wobbled. The wobbling incident light beam forms a distinctively oscillating output signal from the vision detector when the light is focused on the work piece. When the light is not focused on the work piece a distinctive and more constant output signal is produced by the vision detector. For a given position of the work piece, by noting whether the output signal is rapidly changing or relatively constant, the invention can automatically determine whether or not the work piece is at the focal point of the incident light beam.

Abstract: A method and apparatus for laser beam drift compensation. A portion of the laser beam is split off and focused onto a photocell through a reticle. As the laser beam scans the reticle, the actual position of the laser beam is determined and compared with its anticipated position. Compensation is made for any deviation in the beam position in a closed-looped manner to provide accurate optical alignment of the laser beam to the workpiece.

Abstract: An improved method of patterning layers on a semiconductor element by use of laser processing. A thin film of amorphous silicon is deposited on a fused quartz window. Selected regions of the amorphous silicon are crystallized by a laser beam focused through the quartz window. The non-crystallized silicon is removed forming an opaque layer of crystallized silicon in the desired pattern. The quartz window is used as a window to a reactive gas containment chamber containing semiconductor devices to be patterned. By irradiating the chamber with ultraviolet light through the patterned quartz window, the semiconductor element is etched in the regions exposed to the light.

Abstract: An improved method of making masks includes forming a layer of amorphous silicon of about 2,000 angstroms on a transparent substrate. A laser beam is directed through the transparent substrate traverses the amorphous silicon to form a pattern of crystallized silicon. The n-crystallized silicon is etched leaving a patterned substrate. The patterned substrate is used as a mask for exposing photoresist on semiconductor elements.

Abstract: An automatic leveling system and a method of use of the leveling system that is suited for use with electronic components. The system uses an automatic laser focus system to focus on three separate locations on a workpiece, and the information about the focus positions is sent to a control computer. In the control computer the focus information is transformed into information concerning how far the workpiece is from being level. The computer sends signals to pitch and roll goniometers that move in response to the signals, thus leveling the workpiece.

Abstract: A laser power beam control system includes a photodetector for generating an electrical signal which is proportional to the power level of the laser beam. The electrical signal is converted to a high frequency modulated signal which controls a single acousto-optical modulator. The acousto-optical modulator is in the laser beam path and controls the power level of the beam in response to the amplitude modulated signal. The system is particularly adapted to control a laser beam used in raster or vector scanning a laser for the formation of semiconductor integrated circuits.

Abstract: An improved method of patterning a conductive interconnect on a semiconductor element is disclosed. A catalytic layer of, for example, amorphous silicon is deposited on a semiconductor element. The areas over which a conductive pattern is to be formed is activated by directing a focused laser beam onto the amorphous silicon to form crystallized silicon. The amorphous silicon is then etched away after which a conductive material such as a metal is deposited on the activated crystallized silicon.

Abstract: A method and apparatus for controlling the energy of a laser beam on a workpiece includes a photodetector for generating an electrical signal which is proportional to the light reflected from the workpiece. The energy of the laser beam at the workpiece is increased from some predetermined low level until the photodetector senses an abrupt change in the reflected light. This change represents a changed state in the workpiece material that is exposed to the laser beam. The energy level at which the change takes place is used as a reference level for further laser processing.