Patent ID: 7763394

Claim:
Mask (MM) having patterns (MF), for a lithography device operating by reflection of a beam of photons of a wavelength less than about 120 nm, comprising a planar substrate (ST) connected to a reflective structure (SMR) comprising a front face equipped with selected patterns (MF), formed from a material absorbent to the said wavelength, characterised in that it comprises protective means (SP) contacting the reflective structure (SMR) and transparent to the said wavelength and contrived to keep interfering particles (PP) at a distance (H) from the patterns (MF) which is greater than or equal to one of two values taken from a depth of focus (doF) of the device and a height of pattern/interfering particle (h) associated with a tolerated percentage of absorption of photons by the interfering particles (PP) which is a function of their diameter (d), and characterised in that the protective means (SP) form a structure having a membrane (ME) connected by pillars (PS) to the front face of the reflective structure, and in a position substantially parallel to the front face, the thickness of the membrane (ME) and the height of the pillars (PS) being such that their sum is equal to the selected distance (H), the pillars (PS) contacting at least one of the patterns (MF).