Annual report, April 1981 - May 1982 : laser induced deposition of thin films

Abstract

A new chemical vapor deposition (CVD) process has been demonstrated with Si thin films. In this process, reactant gases are heated by absorbing light energy emitted from an IR laser. No other surfaces are heated by the reaction, thus contamination is eliminated, the state (stress, crystallinity, grain size, etc.) of the film can be controlled and unwanted heterogeneous reaction sites are eliminated.

Research conducted to date has employed silane (SiH 4) as a reactant and an untuned CO2 laser. Process conditions appropriate for film deposition have been defined. Deposition kinetics, film characteristics and mixed gas optical absorptivities have been measured. Deposition rates are comparable to other low pressure CVD processes (~ 1-10 A/sec) but with much colder substrate temperatures being permitted. The characteristics of initial amorphous Si films indicate that they equal or exceed the quality of films deposited by highly developed plasma or reactive sputtering techniques.