SELECTING METHOD FOR SEMICONDUCTOR CRYSTAL

• Main Author: HONDA KOUICHIROU
• Format: Patent
• Language: English
• Published: 06.07.1983
• Subjects: AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUSPOLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR; BASIC ELECTRIC ELEMENTS; CHEMISTRY; CRYSTAL GROWTH; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; METALLURGY; PHYSICS; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; REFINING BY ZONE-MELTING OF MATERIAL; SEMICONDUCTOR DEVICES; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; SINGLE-CRYSTAL-GROWTH; TESTING; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL ORUNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL

PURPOSE:To enable the selection of silicon wafers for which the heat treatment of intrinsic gettering is effective, by performing the heat treatment in the specified range of temperature, and by measuring the quantity of the reduced density of oxygen at two or more points of time of heat treatment. CONSTITUTION:In the ambience of nitrogen of 700 deg.C, for instance, in the range of temperature of 600 deg.C-800 deg.C, semiconductor crystals are subjected to heat temperature for 24hr or more. Then the deposition analysis rate y of oxygen is measured, and the result of measurement is drawn in a double logarithmic graph wherein the axis of abscissa shows a time t for heat treatment, while the axis of ordinate shows the deposition analysis rate of oxygen. According to this graph, the inclination n of straight lines can be separated into n=3/2 and n=1/2. The inclination n=3/2 indicates that the precipitate of oxygen grows in silicon crystals due to diffusion. When the heat treatment of high temperature is further applied to these crystals of n=3/2, a stacking fault of high density can be formed inside without exception. Therefore, silicon wafers of excellent quality can be obtained by selecting the silicon wafers of n=3/2.