Method and apparatus for removing and preventing window deposition during photochemical vapor deposition (photo-CVD) processes

Claim 1

The method of depositing a film of a desired atomic or molecular species on a substrate by photochemical vapor deposition, comprising the steps of: positioning the substrate in an evacuated deposition chamber; directing photon light energy through a transparent solid medium into a primary photolysis region in said evacuation chamber positioned between said substrate and said transparent medium; flowing a process gas comprising the desired atomic or molecular species to be deposited as a component part of said process gas into said primary photolysis region, exposing said process gas to said photon light energy in said primary photolysis region to break molecular bonds in said process gas to free the desired atomic or molecular species, and allowing said desired atomic or molecular species to deposit on said substrate; flowing an etchant capable of etching and breaking bonds between the desired atomic or molecular species into said chamber simultaneously with said flow of process gas and directing said flow of etchant to a part of said primary photolysis region that is immediately adjacent said transparent solid medium and remote from said substrate and allowing said etchant to react with said desired atomic or molecular species on and immediately adjacent said transparent solid medium to prevent deposition build-up of the desired atomic or molecular species on said transparent solid medium; and balancing the respective flow volumes and pressures of the process gas and the etchant into said chamber in such a manner that the etchant effectively prevents deposition build-up of the desired atomic or molecular species on the transparent solid medium and is substantially consumed in reaction to create a depletion region in the part of the photolysis region adjacent said transparent solid medium and before reaching said substrate.

Claim 2

The method of depositing a film of a desired atomic or molecular species on a substrate by photochemical vapor deposition, comprising the steps of: positioning the substrate in an evacuated deposition chamber; directing photon light energy through a transparent solid medium into a primary photolysis region in said evacuation chamber positioned between said substrate and said transparent medium; flowing a process gas comprising the desired atomic or molecular species to be deposited as a component part of said process gas into said primary photolysis region, exposing said process gas to said photon light energy in said primary photolysis region to break molecular bonds in said process gas to free the desired atomic or molecular species, and allowing said desired atomic or molecular species to deposit on said substrate; flowing an etchant capable of etching and breaking bonds between the desired atomic or molecular species into said chamber simultaneously with said flow of process gas and directing said flow of etchant to a part of said primary photolysis region that is immediately adjacent said transparent solid medium and remote from said substrate and allowing said etchant to react with said desired atomic or molecular species on and immediately adjacent said transparent solid medium to prevent deposition build-up of the desired atomic or molecular species on said transparent solid medium; and balancing the respective flow volumes and pressures of the process gas and the etchant into said chamber in such a manner that the etchant effectively prevents deposition build-up of the desired atomic or molecular species on the transparent solid medium and is substantially consumed in reaction to create a depletion region in the part of the photolysis region adjacent said transparent solid medium and before reaching said substrate.