Patent ID: 7641806

Claim:
A method of manufacturing an electron beam transmission window of an electron beam irradiation tube having a base membrane having opposed first and second surfaces, first support beams provided on the first surface of the base membrane, and second support beams provided on the second surface of the base membrane, said method comprising the steps of: providing a substrate including: a base membrane forming layer having a first side and a second side; a first layer provided on the first side of the base membrane forming layer; and a second layer provided on the second side of the base membrane forming layer; partially etching the first layer in dry to form the first support beams on the first side of the base membrane forming layer, and to partially expose the first side of the base membrane forming layer between the first support beams, and partially etching the second layer in dry to form the second support beams on the second side of the base membrane forming layer and to partially expose the second side of the base membrane forming layer between the second support beams, thereby forming a structure including the base membrane provided by the base membrane forming layer and having the first and second surfaces provided by the first and second sides of the base membrane forming layer, respectively, the first support beams formed of parts of the first layer and provided on the first surface of the base membrane and the second support beams formed of parts of the second layer provided on the second surface of the base membrane; and forming a coating layer of SiN on the structure such that the coating layer covers whole surfaces of all of the first and the second support beams, and also covers whole areas of the first surface of the base membrane exposed between the first support beams, and also covers whole areas of the second surface of the base membrane between the second support beams.