Selective oxidation method of semiconductor substrate

Abstract

Abstract PURPOSE: To prevent impurity exudation to element regions from field regions and produce an IC of superior dynamic characteristics by superposing an ion implanting mask of an outside dimension larger than that of a field oxidizing mask on the field oxidizing mask. CONSTITUTION: SiO 2 12, Si 3 N 4 13, SiO 2 thick film 14 are laminated on a P type Si substrate 11. Resist 15 is provided slightly wider than element forming regions. When the substrate is treated with HF after treatment for about 10 minutes in CF 4 plasma, the film 14 under the resist is etched away, leaving the film 14 of an inverted taper. The taper may be controlled as desired depending upon treatment conditions. The film 13 is etched away through the mask 14 and B ions are implanted to create a p + layer 16. If an oxide thick film 17 is created through high temperature oxidation through the mask 13, B does not exudate in the element region because the ion implantation mask 14 is wider than the selective oxidation mask 13. Next, the films 13, 12 are selectively opened with holes, where gate film 18 and poly Si 19 are provided, and n + type source, drain 20, 21 are made. This constitution obviates the decrease in operating speed and enables desired channel widths to be obtained COPYRIGHT: (C)1979,JPO&Japio

Inventors

• 👤 Sunao Shibata

Bibliographic Details