Abstract: Plasma ashing and/or etching using a solid sapphire disk is disclosed. A plasma etcher/asher of one embodiment of the invention includes at least a chamber body, upper and lower baffles, and a solid sapphire disk. The chamber body defines an interior chamber in which a semiconductor wafer is positionable for etching or ashing. The baffles are positioned over the semiconductor wafer, and distribute gas onto the semiconductor wafer. The solid sapphire disk has no holes, and is positioned over one of the baffles to affect distribution of the gas onto the semiconductor wafer. The solid sapphire disk of the invention provides for more uniform distribution of the gas onto the semiconductor wafer. As a result, etching or ashing of the semiconductor wafers occurs more uniformly, providing for more uniformly thick wafers.