MANUFACTURE OF X-RAY MASK

摘要

PURPOSE:To suppress an increase in the intensity of transmitted X-rays in the central part of a Ta pattern due to Fresnel diffraction and thereby to prevent the lowering of a mask contrast by a method wherein the section of the pattern is sloped to be shaped in a trapezoid by dry etching with a fluorocarbon gas. CONSTITUTION:When reactive ion etching with a fluorocarbon gas in conducted under a high pressure of about 14Pa, chemical etching due to a radial reaction is predominant over a physical sputtering effect due to ions and side etching occurs on a Ta pattern 2. Since the depth of this side etching is proportional to a time during which each part of the Ta pattern 2 is exposed to plasma, the Ta pattern 2 sloped smoothly is formed consequently. Thereby the lowering of a mask contrast due to Fresnel diffraction can be prevented.