| 摘要 |
1,066,911. Semi-conductor devices. STANDARD TELEPHONES & CABLES Ltd. Dec. 23, 1965 [Jan. 1, 1965], No. 58/65. Heading H1K. In preparing a semi-conductor layer of closely controlled thickness, holes are formed to a predetermined depth in one face of a semi-conductor wafer and lined with insulating material prior to depositing a layer of semiconductor material on said face and in the holes. The wafer thickness is then reduced from the opposite face until the insulating material is exposed, at least the first stage of removal being by etching. In one embodiment an oxide layer is grown on one face of a high resistivity silicon wafer, holes formed in it by photolithographic and etching techniques and silicon removed through said holes to a depth of 15Á by etching in a hydrogen-hydrogen chloride mixture at 1200‹ C. The internal surfaces of the cavities are then oxidized 5 (Fig. 2), and after removal of oxide from the surrounding surface low resistivity silicon 6 is epitaxially deposited over it. Material is then removed by lapping or grinding the opposite face of the wafer prior to etching in hydrogen chloride until the oxide 5 becomes visible. Where it is desired to identify the interface between the original wafer and the epitaxial layer the oxide layer is not removed from the wafer periphery before the layer is grown. The wafer and grown layer may alternatively be basically different semi-conductor materials of any resistivity.
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