Patent ID: 8067067

Claim:
A method of providing a plasma-resistant coating on an aluminum or aluminum alloy substrate, where the substrate is a surface of a plasma processing apparatus, wherein said method comprises applying a coating over at least a portion of a surface of said substrate, wherein said coating includes an oxide of an element selected from the group consisting of Y, Sc, La, Ce, Eu, Dy, and combinations thereof, wherein said coating, which is an oxide of an element selected from said group, is applied to said substrate surface using a technique selected from the group consisting of thermal/flame spraying, plasma spraying, and chemical vapor deposition (CVD), and wherein said substrate surface is preheated to a depth of at least 250 mils to a temperature of at least 150° C., and prior to application of said coating over said preheated substrate surface, followed by cooling of said coated substrate to place an exterior surface of said coating in compression, so that a porosity of said coating at said coating exterior surface is less than 1.5%, followed by reaction of said exterior surface of said coating with a dilute acid solution comprising about 0.1 volume % to about 5 volume % HF, about 1 volume % to about 15 volume % HNO 3 , and about 80 volume % to about 99 volume % deionized water, to create a fluoride of an element selected from said group upon said exterior surface of said coating, and wherein said exterior surface of said coating provides an average erosion rate of said coating when exposed to a fluorine-comprising plasma of about 243 Å/min or less. [The claim has been amended to clarify that the limitation “substrate” pertains to a surface of a plasma processing apparatus, and not to a substrate (work piece) being processed].