Projection electron-beam lithography masks using advanced materials and membrane size

A stencil or scatterer mask for use with charged particle beam lithography such as projection electron-beam lithography comprises a membrane layer of a material having a Young's modulus of at least about 400 GPa and support struts supporting a surface of the membrane. The struts form and surrounding a plurality of discrete membrane areas of different aspect ratios aligned to design regions of an integrated circuit. The discrete membrane areas have different aspect ratios range from about 1:1 to about 12:1, and the discrete membrane areas have different size surface areas. The membrane is preferably silicon carbide, diamond, diamond-like carbon, amorphous carbon, carbon nitride or boron nitride. When used in scatterer masks, the ratio of discrete membrane area to membrane thickness is at least about 0.18 mm2/nm. When used in stencil masks, the ratio of discrete membrane area to membrane thickness is at least about 1.0 mm2/nm. The stencil mask is made by depositing a diamond membrane film patterned with a hardmask layer on a substrate, depositing an etch stop layer adjacent the diamond film, and forming supporting struts surrounding a plurality of discrete areas of the membrane film. The method then includes depositing a pattern over the membrane film within the discrete membrane film areas, the pattern conforming to one or more desired circuit elements, and etching the membrane film with a reactive ion etch containing oxygen to form openings in the membrane film.