Abstract: Silicon wafers oriented in the (100) crystal planes are sawed from a silicon ingot using the (111) faces on the as drawn silicon ingot as reference planes. The reference planes permit determination of the ingot orientation during the sawing process.

Abstract: A method of improving the yield and achievable tolerances of integrated circuits by obtaining surface measurements of non-reflective soft mounting films used in integrated circuit manufacture. The non-reflective surface of a mounting film is first rendered reflective by applying a reflective water atop the film surface. This reflective test wafer, which is highly plano-parallel and preferably has a thickness less than that of the ultimate product wafer, is applied to the mounting film to be measured via direct pressure whereby the reflective test wafer conforms to and takes on the surface characteristics and contours of the film. The formerly non-reflective surface of the mounting film is thereby rendered effectively reflective and thus susceptible to optical profiling and graphical and numerical recordation by a computerized interferometer in accordance with well-known techniques.

Abstract: An improvement in silicon wafer flatness is obtained by reducing the time spent in polishing the wafer. After a conventional lapping operation, the wafer is coated with an etch resistant coating, typically silicon nitride. A polishing step removes the nitride coating on the flat surfaces of the wafer, but leaves a nitride coating on the sides of pits that are formed in the lapping operation. The wafer is then etched, typically in KOH, to remove the silicon surface to below the depth of the pits. The undercutting of the nitride coating removes the pits, or leaves relatively small protrusions in their place. The protrusions may be removed by a short polishing operation. Other wafer types and etch-resistant materials are possible. Integrated circuits are typically formed on the wafers by lithography techniques that advantageously utilize the improved flatness.

Abstract: A method for batch-contouring crystal plates for frequency adjustment is disclosed. A plurality of plates is secured to a compliant sheet and the sheet is attached to an applicator surface which includes a resilient pad. The plates are then abraded against another surface to produce contours on all the plates. The resilient pad provides spring loading to insure uniform pressure on all the plates.

Abstract: A method of contouring crystal plates for frequency control. After plate dimensions are established, the plates are kept in a stack separated by a bonding material. The stack is immersed in an etchant which etches the exposed crystal edges in a manner which undercuts the bonding material, thus batch forming bevel contours on at least the outer portions of the major faces of each plate in the stack.

Abstract: A method and apparatus for checking the orientation of crystal plates in a stacked configuration. The plate stack (15) is placed between a polarizer (11) and analyzer (12). A cylindrical lens (13) placed between the stack and analyzer is utilized as a convergent element. Included with the stack are reference plates (17, 18) having known orientation angles representing the upper and lower limits of the desired orientation tolerance. Monochromatic light is made incident on one surface of the plates in the stack through the polarizer. Since the crystals are birefringent, an interference pattern will be produced by light emerging from the opposite surface. Due to the presence of the cylindrical lens, this pattern can be viewed as a series of essentially linear, parallel bands of light. Deviations within a particular band are compared with bands produced by the reference plates to determine if the angle of each plate falls within the desired limits.

Abstract: A method which permits highly stable frequency adjustment of piezoelectric crystal devices to tight tolerances. Small fragments of the crystal (10) which resemble conchoidal shells (18) are removed from at least one surface (11) of the crystal plate by fracturing. In one example, this is accomplished by applying pressure from a sharp-pointed stylus (20) near the edge of the plate.