| 摘要 |
1,209,313. Transistors. JOSEPH LUCAS (INDUSTRIES) Ltd. 1 March, 1968 [11 April, 1967], No. 16543/67. Heading H1K. A high voltage transistor is produced by the steps shown in the flow sheet, which comprise: 1. starting with a wafer of N-type silicon which forms the collector region; 2. diffusing-in phosphorus to form N+ type regions; 3. removing the upper N+ type region by etching or lapping; 4. diffusing-in aluminium from the vapour to produce a P-type surface region; 5. removing part of the P-type region by photomasking and etching; 6. heating in an oxidizing atmosphere to redistribute the aluminium so that the maximum concentration is below the surface and the gradient is shallow at the collector junction, to form the base region; 7. diffusing-in boron to form a P+ type region; 8. removing the P+ type region from the N- type wafer and heating in wet oxygen to form a glass layer; 9. forming a window in the glass layer and diffusing phosphorus through the P+ type region into the P-type region to form the emitter region; 10. (not shown) heating in wet oxygen to further redistribute the impurities; 11. (not shown) applying emitter, base and collector contacts, all to the top surface if desired.
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