Low voltage Zener diode prodn. - by etching substrate and epitaxial deposition of p-silicon through window on N-silicon body

摘要

In the prodn. of Zener diodes with a Zener voltage of 2.4-3.3.V an n-Si body is provided with an insulating film having a window and a strongly p-doped Si layer is deposited on the exposed surface by selective (gas phase) epitaxy. Growth involves cleaning the exposed surface by etching at a first temp. and deposition at a second, lower temp. The n-Si body pref. has a specific surface resistance of 0.003-0.004 ohm.cm and an overall specific resistance in the same region. The epitaxial Si film is 5-20 micron thick, whilst the insulating film is an oxide and is 0.5-1.5 micron thick. It has a ring with a width of 0.002-0.004 cm and an inside window dia. of 0.002-0.035 cm. The p-conductive film has a specific resistance of 0.001-0.003 ohm.cm and is of such a thickness that the pn-junction on its underside is not influenced physically or electrically by a conductor electrode applied to the p-conductive film, a suitable thickness being in the 1.5-3.0 micron range. Diodes with a low voltage and excellent electrical properties are produced in a relatively simple process without special costs.