Process for the formation of a functional deposited film by way of microwave plasma CVD method

Claim 1

In a microwave plasma chemical vapor deposition process for the formation of a functional deposited film on a plurality of cylindrical substrates by means of a microwave plasma chemical vapor deposition conducted in a substantially enclosed cylindrical film-forming chamber, said film-forming chamber comprising a circumferential wall having an end portion thereof hermetically provided with a microwave introducing window to which a waveguide extending from a microwave power source is connected, said film-forming chamber having a discharge space and a plurality of rotatable cylindrical substrate holders therein, each of said substrate holders being capable of having one of said cylindrical substrates positioned thereon, said substrate holders being concentrically arranged in said film-forming chamber so as to circumscribe said discharge space, said film-forming chamber being provided with means for supplying a film forming raw material gas into said discharge space and means for evacuating said film-forming chamber, wherein said process includes forming a functional deposited film on each of said cylindrical substrates by generating a plasma by microwave glow discharge in said film-forming raw material gas to form said functional deposited film while simultaneously rotating said cylindrical substrates, the improvement which comprises the steps of: (a) monitoring an effective power of microwaves to be introduced into said film-forming chamber, (b) generating an output signal indicative of the effective power of said microwaves corresponding to a given plasma intensity, and (c) controlling a match between (i) said effective power of said microwaves corresponding to a given plasma intensity in film-forming chamber and (ii) said microwaves to be introduced into said film-forming chamber in accordance with said output signal to thereby maintain the plasma intensity constant in said film-forming chamber irrespective of the time elapsed, whereby a functional deposited film exhibiting enhanced uniformity in thickness and in quality is formed on each of said cylindrical substrates at a high deposition rate.