Apparatus and process for controlling
etching of
silicon-based or organic materials on large rectangular substrates for manufacture of
flat panel displays or other devices. The disclosed
etching process can remove
silicon-based materials or organic polymers with a rate distribution such that all areas of the panel are finished at nearly the same time. It does so while minimizing electrical charging of the workpiece that could cause damage to the devices. The
etching chamber employs a
parallel plate RF discharge between two electrodes, one of which is the showerhead for gas introduction and the other supports the substrate to be processed. Reactant and other gases are provided to the
discharge by a novel showerhead structure. The gases which provide reactants for etching
silicon-based materials include halogenated compounds.
Oxygen,
water vapor or
hydrogen with other gas additives may be used for etching organic polymers. The uniformity of etching across the substrate is controlled by adding other gas(es), including
inert diluents, which can control the
etching rate for either silicon-based materials or organic materials by accelerating and / or decreasing it. In addition, the distribution of the gases which are added can be varied to make the surface potential of the substrate more uniform. With a showerhead having a single reservoir that feeds all gases into the
discharge, the gases may be added to the reservoir through multiple distribution structures within or adjacent to the reservoir. These structures are each supplied separately with the additive gases and, in turn, feed them to the different regions of the reservoir. The invention can thus provide different etching rates for different parts of the substrate, as may be required to finish film removal in all areas of the panel at nearly the same time. The invention also provides for
chemical conversion of inorganic residues remaining after the oxidation of an
organic polymer in the
ashing process by addition of small amounts of halogenated gas(es) to the mixture flowing through the
plasma sources. With the
system and process of the invention, space efficiency,
operating cost and
capital cost for making large substrates can be reduced significantly.