Abstract: In an etch monitor system, a method and apparatus for adjusting the angle of incidence to normal between a laser beam and a reflective surface, such as a silicon wafer, includes a rotatable mirror having a pinhole formed therethrough, the rotatable mirror moveably mounted to be positioned in a first location within a light path and a second location out of said light path. When the rotatable mirror is located in the light path, the pinhole allows a beam of the laser beam to pass from a laser source to the reflective surface. If the beam is normal to the reflective surface, the beam is directed back toward the laser source through the pinhole. If the beam is not normal to the reflective surface, the beam is reflected by the rotatable mirror to a target, allowing observation on a lit spot of the target to enable normalization by making appropriate adjustments.

Abstract: An etch rate monitor for use with semiconductor wafer etching processes includes a source of light of normal incidence to the wafer surface through a window in the etching chamber. In a first embodiment, a Fresnel or positive lens is used to collect some of the diffraction orders caused by the repetitive patterns on the wafer surface which merge from the window. In alternate embodiments, a concave spherical mirror and/or a photodetector system are used to collect the diffraction orders. A collimating lens applies these diffraction orders of normal incidence to interference filters which reject plasma and ambient light and pass the diffraction orders to a photodetector to monitor etch rate as a function of the cycle period between interference minima or maxima caused by the difference in path length between the etched and not etched surfaces of the wafer.

Abstract: An inner lid is attached to a vacuum chamber, covering an inner region of the vacuum chamber. An outer lid, also attached to the vacuum chamber, covers the inner lid, leaving a region between the inner lid and the outer lid. A gas conduit allows gas to flow between the inner region of the vacuum chamber and the region between the inner lid and the outer lid. A filter is placed in or immediately outside the gas conduit to prevent particles from entering the inner region of the vacuum chamber from the region between the inner lid and the outer lid. Since the pressure is the same on the top and bottom of the inner lid, the inner lid does not flex and thus does not rub against the vacuum chamber when the vacuum chamber is pumped down or vented up.

Abstract: A semiconductor wafer is provided with magnetic material about the periphery for magnetically clamping the wafer on a seating gasket at the processing station. The seating gasket is annular for peripherally supporting the wafer. An electro-magnet establishes a peripheral station magnetic field which attracts the wafer magnetic material to form the clamp. The station magnetic field may by reversed to levitate the wafer onto and off of the seating gasket.

Abstract: An inner lid is attached to a vacuum chamber, covering an inner region of the vacuum chamber. An outer lid, also attached to the vacuum chamber, covers the inner lid, leaving a region between the inner lid and the outer lid. A gas conduit allows gas to flow between the inner region of the vacuum chamber and the region between the inner lid and the outer lid. A filter is placed in or immediately outside the gas conduit to prevent particles from entering the inner region of the vacuum chamber from the region between the inner lid and the outer lid. Since the pressure is the same on the top and bottom of the inner lid, the inner lid does not flex and thus does not rub against the vacuum chamber when the vacuum chamber is pumped down or vented up.

Abstract: A method for endpoint detection in a semiconductor wafer etching system characterized by the steps of: 1) scanning a semiconductor wafer with a narrowly focused laser beam; 2) analyzing a reflected portion of the beam to determine a preferred parking spot on a preferred flat area of the wafer; 3) parking the beam at the preferred spot; and 4) analyzing the reflected portion of the beam to determine when the preferred flat area has been etched through. The beam spot of the laser beam is smaller than the width of the preferred flat area to eliminate noise generated at the transition boundaries of the flat area. Preferably, the wafer is scanned several times along the same beam path to permit the comparison of several scans to determine the preferred parking spot.

Abstract: A semiconductor wafer is provided with magnetic material about the periphery for magnetically clamping the wafer on a seating gasket at the processing station. The seating gasket is annular for peripherally supporting the wafer. An electro-magnet establishes a peripheral station magnetic field which attracts the wafer magnetic material to form the clamp. The station magnetic field may by reversed to levitate the wafer onto and off of the seating gasket.

Abstract: A method for focussing a radiant energy beam characterized by the steps of scanning a beam of radiant energy across a test pattern including areas of differing reflectivity, detecting the variance in a reflected portion of the scanned beam and adjusting the beam to minimize the variance. Preferably, the test pattern includes areas of varying widths, e.g. relatively non-reflective areas of varying widths separated by reflective areas of uniform widths. As the beam is scanned perpendicularly across the test pattern it will be highly reflected by the reflective areas and will be partially absorbed by the non-reflective areas. If the beam is wider than a non-reflective area a portion of the beam will be absorbed and a portion of the beam will be reflected, resulting in a greater total reflection than if the beam is narrower than the non-reflective region.

Abstract: A method for endpoint detection in a semiconductor wafer etching system characterized by the steps of: (1) scanning a semiconductor wafer with a narrowly focussed laser beam; (2) analyzing a reflected portion of the beam to determine a preferred parking spot on a preferred flat area of the wafer; (3) parking the beam at the preferred spot; and (4) analyzing the reflected portion of the beam to determine when the preferred flat area has been etched through. The beam spot of the laser beam is smaller than the width of the preferred flat area to eliminate noise generated at the transition boundaries of the flat area. Preferably, the wafer is scanned several times along the same beam path to permit the comparison of several scans to determine the preferred parking spot.

Abstract: A cassette of conventional form is loaded with a plurality of semiconductor wafers having indexing flats of the known type and placed over three parallel rollers rotatably secured to a frame. The three rollers include a center roller and two side rollers positioned only slightly higher than the center roller such that their rotary motions can be communicated to the wafers by contact, depending on the position of the individual indexing flats. The indexing flats are roughly aligned in downward directions first by rotating only the center roller and after all three rollers are rotated to bring the indexing flats in upward directions, the wafers are more accurately aligned in a downward direction by rotating only the center roller and all three rollers are rotated thereafter for a predetermined period of time, depending on the desired angular position of the indexing flats.