Workpiece Processing Apparatus with Gas Showerhead Assembly

A method for processing a workpiece in a processing apparatus, the workpiece comprising a top side and a back side, the method comprising:

• placing the workpiece on a workpiece support disposed in a processing chamber;
• emitting, by one or more radiative heat sources, radiation directed at one or more surfaces of a workpiece to heat at least a portion of a surface of the workpiece;
• distributing, by a gas showerhead assembly, one or more process gases towards the top side of the workpiece;
• and obtaining a temperature measurement indicative of a temperature of the workpiece, wherein the gas showerhead assembly is transparent to electromagnetic radiation emitted from the one or more radiative heat sources,
• wherein the gas showerhead assembly comprises one or more gas diffusion mechanisms to distribute gas within the enclosure,
• wherein the gas showerhead assembly comprises an enclosure having a top cover and a plurality of gas injection apertures, wherein the gas delivery system comprises a first radial gas distribution channel and a first radial gas injection barrier, wherein gas flowing radially around the first radial gas distribution channel can diffuse or flow though one or more gas diffusion apertures disposed in the first radial gas injection barrier, the gas diffusion apertures configured to facilitate horizontal flow of the one or more process gases,
• wherein the gas showerhead assembly is transparent to electromagnetic radiation emitted from the one or more radiative heat sources,
• wherein the gas showerhead assembly comprises a gas distribution plate, the gas distribution plate including a gas diffusion barrier disposed generally perpendicular to a horizontal axis of the gas distribution plate such that the gas diffusion barrier extends from the gas distribution plate to a region between the gas distribution plate and the top cover of the enclosure such that a gap is between the gas diffusion barrier and the top cover of the enclosure.