Abstract: A system for non-contact measurement of thickness of a test object. A laser beam is split into two identical directly opposed input beams. A calibration object of known thickness causes beams to be reflected from sides of the test object. Each reflected beam passes through sensing means including a pinhole aperture and a photodiode sensor. Maximum sensor output defines first and second focal points a known distance apart. The calibration object is removed, and the test object is inserted into the path of the input beams, creating focus position intensity curves for the reflected beams. By determining the deviation, at maximum photodiode output, of the positions of the test object reflecting surfaces from the positions of the calibration object surfaces, the test object thickness can be readily and accurately determined.

Abstract: A system for non-contact measurement of thickness of an object. A laser beam is split into two identical input beams that are directly opposed. A calibration object of known thickness causes beams to be reflected from sides of the test object. Each reflected beam passes through auto-focus means including a quad sensor coupled to focusing means on the input beam, causing each input beam to be focused on the calibration object, thereby defining first and second focal points a known distance apart. The focus is locked and focus error data are generated for each beam. The calibration object is removed, and the test object is inserted into the path of the focused input beams, creating focus error signals for the reflected beams. By determining the deviation of the positions of the test object reflecting surfaces from the positions of the calibration object surfaces, the test object thickness can be readily and accurately determined.

Abstract: In a system for locating and measuring an index mark on an edge of a wafer, a wafer to be examined is positioned and centered on a chuck in a horizontal chuck position such that an index mark is oriented within first and second index mark orientation features disposed on the chuck. The chuck is translatable, tiltable between horizontal and vertical positions, and rotatable over an angle subtended by the index mark orientation features of the chuck. A laser beam from a laser beam optical profiler is focussed on the surface of the wafer at a distance proximate the wafer edge and proximate the first index mark orientation feature of the chuck. The chuck is rotated in a direction from the first to the second index mark orientation feature whereby a reflected portion of the laser beam generates data corresponding to the angular location of index mark edges. An index mark center location is computed.

Abstract: A fully automated surface profiling system having a loading chamber and an adjacent measurement chamber containing a phase differential laser optical scanning system and a five-axis positioner having a vacuum chuck for holding and orienting a wafer for surface profile measurement. The positioner can displace a mounted wafer lengthwise and crosswise of the chamber, can rotate the wafer about vertical and horizontal axes through the positioner, and can rotate the wafer about its own axis. Each motion is motor-driven and can be carried out independently of all the others or in compound motion as needed. The positioner can accommodate a series of replaceable chucks for holding wafers of different diameters. The loading chamber has a cassette dock for receiving a cassette containing wafers to be tested, a robotic server, and a prealigner. All operations within the profilometer are controlled by a programmable CPU at a control station.

Abstract: An optical profilometer having a movable head for measurement of the profile of a surface of a wafer under test in response to an optical beam projected by the head and incident onto the surface. The wafer may be a substrate for a data storage disc, and the surface may be one of a plurality of surfaces of the wafer, including the side face, the edge, and a radius or bevel therebetween. A fixture for holding the wafer includes a frame for orienting the wafer and also pivotally rotating the wafer about an axis. A vacuum chuck holds the wafer on the frame. An actuator orients the fixture frame in an plurality of positions spaced angularly about the axis to present selected ones of the wafer surfaces to the beam for profile measurement. Wafers of various diameters may be accommodated on the fixture.

Abstract: A previewing profiler includes apparatus to scan the surface of an object and to provide a display relating to the smoothness of the surface at a microscopic level. The system includes providing a polarized collimated laser beam through a Nomarski type prism and focusing the resulting beams on the surface to be scanned. The system further includes a user operable rotatable mirror which may be inserted, upon operator command, between the laser and Nomarski prism, which mirror is designed to leak a small percentage of the laser light. Another source of noncollimated polarized light, provided through a condensing lens, is provided to the rotatable mirror to be directed along the same path through the Nomarski prism and to be focused at a point above the surface being scanned, thereby providing a substantially larger illuminated area on the surface. The reflected light from both the laser beam and additional noncollimated light is focused on a CCD array and then displayed on a display.