| 摘要 |
1,072,986. Semi-conductor devices. PHILCOFORD CORPORATION. Sept. 29, 1964 [Sept. 30, 1963], No. 39684/64. Heading H1K. Semi-conductor material is deposited on an area of a semi-conductor wafer by forming a masking band of oxide on the wafer around the area and then epitaxially depositing semi-conductor material on the area. The band must be narrow enough to prevent formation of crystallites thereon. In a typical case a wafer of N-type silicon the surface of which is inclined at 0À5-4 degrees to a 111 crystallographic plane is etched and a thermal oxide film grown on it. The film is removed by photolithographic techniques except from areas 14, 16, 18 and 30 (Fig. 3). After further conventional cleaning steps the wafer is blown dry in nitrogen and placed in a reaction chamber. It is raised to 1200-1400‹ C. by R.F. heating while the chamber is flushed out with hydrogen. P- type silicon is then deposited on the unmasked areas from a flow of hydrogen containing silicon tetrachloride and boron tribromide and the wafer afterwards cooled in flowing hydrogen. The surface is next reoxidized and holes formed in the oxide to expose areas to which contact is made by metal vapour deposited through a mask to provide a series of interconnected PN diodes (Fig. 9, not shown). Alternatively the new oxide layer is selectively removed by photolithography to re-expose areas within the original rings 14, 16 and N-type silicon deposited thereon from a mixture of silicon tetrachloride, phosphorus trichloride and hydrogen. The surface may again be reoxidized and suitable contacts made through holes in the oxide to the resulting transistor zone configurations. |
