High contrast ratio membrane mask
AssigneeNEC Corporation
InventorFumihiro Koba
Life of this patent
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Abstract
A membrane mask for use in an electron beam lighography or X-ray lighography has a membrane film formed on a silicon wafer, and a mask body pattern formed on the membrane film. The membrane film has a heavy-metal-implanted area underlying a portion of the mask body pattern other than the opening of the mask body pattern. The implanted area achieves a higher contrast ratio in the pattern obtained from the membrane mask.
Claims12
A membrane mask comprising a wafer, a membrane film including a first material and supported by said wafer, and a mask body overlying said membrane film, said mask body having a mask pattern including an opening, said membrane film having a first area underlying said mask body other than said opening, said first area being formed by addition of atoms having an atomic number higher than an atomic number of said first material.
A method for fabricating a membrane mask comprising the steps of:
- forming a membrane film supported on a wafer;
- forming a resist mask on said membrane film;
- selectively implanting atoms into said membrane film by using said resist mask to form an implanted area, said atoms having an atomic number higher than an atomic number of a material included in said membrane film;
- forming a mask body film on said membrane film including said implanted area;
- and
- patterning said mask body film to have a pattern including an opening exposing said membrane film other than said implanted area.
Dependencies are inferred from the claim text.