Ceramic membrane device and a method of producing the same

Abstract

A ceramic membrane device for a photomask is a ring-shaped base plate constituting a circumferential frame and having a flat front surface, an outer side surface and a rear surface, a front CVD coating supported on the front surface of the base plate and defining a flat surface on which a masking pattern is to be formed, and a rear CVD coating formed on the rear surface of the base plate. The front and rear CVD coatings are made of a silicon compound. The ceramic membrane device is made by providing a plate having a flat front surface, a side surface and a rear surface, forming a front CVD coating made of a silicon compound on the side surface and the front surface of the plate, forming a rear CVD coating made of a silicon compound on a partial area of the rear surface of the plate so that an uncoated area remains, removing the portion of the plate corresponding to the uncoated area by means of etching so that the remaining portion of the plate can function as a circumferential frame for the ceramic membrane formed by the front coating.

Dependencies are inferred from the claim text.