| 摘要 |
918,568. Etching. WESTINGHOUSE ELECTRIC CORPORATION. June 21, 1961 [July 18, 1960], No. 22396/61. Class 100 (2). [Also in Group XXXVI] The performance of a tunnel diode is improved by etching it in the region of the junction while passing a current through it, either continuously or from time to time so as to monitor its electrical characteristics, the etch being of such low conductivity as not to affect substantially the performance of the diode. As shown in Fig. 1, a semi-conductor device which may be of silicon, germanium or gallium arsenide and has a PN junction with tunnel diode characteristics is immersed in a low-conductivity etch 18. A forward current from source 14 passes through the junction and a cathode-ray tube 16 traces the characteristic of the device, etching being allowed to proceed until the characteristic is satisfactory. The etching process removes a peripheral area 22 about the PN junction. Suitable etching solutions contain from 1 to 10 parts by volume of 90% fuming red nitric acid, 1-15 parts of 80% acetic acid, 1-10 parts of 50% hydrofluoric acid and 0.1 to 4 parts of bromine per 100 parts of solution. Specific etches in this range are described.
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