A method of obtaining a mask for X-ray lithography having a thin oxide film supported on an annular silicon base includes the following steps:(a) deposition of an oxide layer such as titania or zirconia, on a silicon or copper substrate;(b) etching selectively a portion of the backside of the substrate, obtaining a membrane on the etched portion; and(c) obtaining a pattern delineation through a photoresist on the membrane framed by the silicon or copper substrate.The mask prepared according to the present invention does not suffer from any distortion and preserves its accuracy even under the stresses incurred during the mask preparation and use.