Cvd process for forming a thin film

Abstract

The present invention is a CVD process for forming a thin film which includes a step of recovering an organometallic compound component from an exhaust gas which has been conventionally discarded, and a purifying step of purifying the recovered organometallic compound to thereby eliminate a by-product formed in a film forming step by CVD. According to this process, the organometallic compound is recycled. As a recovering technique, any of the followings is employed: a technique in which the exhaust gas is cooled and is recovered as a recovered content; a technique in which the exhaust gas is brought into contact with a solvent to dissolve the organometallic compound in the solvent; and a technique in which the exhaust gas is brought into contact with an adsorbent to thereby adsorb the organometallic compound. A purifying technique is selected depending on the recovering technique or the properties of the recovered content, and any of a technique of distilling the recovered content, a technique of sublimating the recovered content, and a technique of heating the adsorbent to desorb the organometallic compound is employed. These CVD thin film processes can recover and purify the organometallic compound in a higher yield by adding a step of eliminating oxygen from the exhaust gas prior to the recovering step.

1 . A CVD apparatus for producing a thin film comprising a container for accommodating an organometallic compound as a material, a heating means for heating the solution to thereby vaporize the organometallic compound to yield a source gas, and a reactor for allowing said source gas to react to thereby form a thin film of a metal or metaloxide on a substrate,
 wherein said apparatus further comprises, on the downstream side from the reactor, a recovering means for obtaining a recovered content containing the organometallic compound from an exhaust gas, said exhaust gas being composed of a reaction product formed through a reaction and an unreacted source gas, and a purifying means for separating and purifying the organometallic compound from said recovered content.   
   
   
       2 . A CVD apparatus for producing a thin film according to  claim 1 , further comprising, between the reactor and the recovering means, an oxygen eliminating means for eliminating oxygen from the exhaust gas. 
   
   
       3 . A CVD apparatus for producing a thin film according to  claim 1 , wherein said recovering means is a cold trap in which the exhaust gas is cooled to yield the recovered content in a liquid state. 
   
   
       4 . A CVD apparatus for producing a thin film according to  claim 2 , wherein said recovering means is a cold trap in which the exhaust gas is cooled to yield the recovered content in a liquid state. 
   
   
       5 . A CVD apparatus for producing a thin film according to  claim 1 , wherein said recovering means is a solvent tank for containing a solvent in which the organometallic compound is soluble. 
   
   
       6 . A CVD apparatus for producing a thin film according to  claim 2 , wherein said recovering means is a solvent tank for containing a solvent in which the organometallic compound is soluble. 
   
   
       7 . A CVD apparatus for producing a thin film according to  claim 1 , wherein said recovering means is an adsorption tank filled with an adsorbent capable of adsorbing the organometallic compound. 
   
   
       8 . A CVD apparatus for producing a thin film according to  claim 2 , wherein said recovering means is an adsorption tank filled with an adsorbent capable of adsorbing the organometallic compound.