A chamber includes a substrate, a chamber layer disposed on the substrate that defines the sidewalls of the chamber, and the chamber layer has a chamber surface. The chamber has an area in the plane formed by the chamber surface in the range from about 1 square micrometer to about 10,000 square micrometers. The chamber also includes an orifice layer disposed over the chamber layer. The orifice layer has a first and second orifice surface and a bore wherein the bore has an area in the plane formed by the first orifice surface less than the chamber area. The chamber further includes a protective layer deposited, through the bore, on the sidewalls of the chamber layer and a portion of the first orifice surface.