JPS6417860A - Thin film forming device - Google Patents

Abstract

PURPOSE:To decrease the heating of a substrate by thermions and to form a thin film even on the substrate having small heat resistance by disposing a grid of a positive potential between the substrate and gas ejection port at the time of ionizing gaseous raw materials in a vacuum vessel and forming the thin film consisting of the gaseous components on the substrate. CONSTITUTION:A substrate 24 and a gaseous raw material discharge port 8 for forming the thin film are provided in the vacuum vessel 3 and the gaseous mixture composed of the gaseous material such as SiH4 and inert gas such as Ar is ejected from the discharge port 8 and is heated by a heater 13. Gaseous O2 and gaseous Ar are supplied thereto from another cylinders 20, 22. The gaseous SiH4 is activated by the thermions generated by energization of a filament 7 provided in the upper part of the gas ejection port 8 and is thereby brought into reaction with the gaseous O2 to form the thin film of SiO2 on the substrate 24. The thermions generated from the filament 7 in this case are absorbed by the grid 6 of the positive polarity and the quantity at which the thermions collide against the substrate 24 is small and, therefore, the substrate 24 is not heated to a high temp. and even materials such as plastic having weak heat resistance are usable as well.