The size of semiconductor production equipments for dry etching, sputtering and ashing has been increasing due to increasing Si wafer size, where plasma is effectively used for micro fabrication on the Si wafer. Up to now, alumite film and bulk ceramics have been used as a shield to protect from the plasma, which easily erode chamber parts mainly composed of aluminum, resulting in frequent maintenance and decrease of yield ratio of the Si device. Recently, increase of the plasma power due to increasing equipment size has caused unreliability of the alumite film. Also, it becomes difficult to produce large scaled bulk ceramics in spite of higher durability. Therefore, application of ceramic coatings prepared by plasma spraying for the shield has been sharply increasing in the last few years. In spite of using spray coatings, mechanism of the plasma erosion and performance of the spray coatings are presently still unclear. In this work, plasma-erosion properties of the plasma spray coatings of alumina and yttria are studied and mechanism of the plasma erosion is discussed. Further, novel ceramics for the semiconductor production equipments are proposed.