Pattern writing method during X-ray mask fabrication

DETAILED DESCRIPTION The above problems and others are at least partially solved and the above purposes and others are realized in a pattern writing method for membrane structure fabrication including the steps of forming a membrane structure, and forming a material system on the membrane structure including the steps of providing a layer of material with internal stresses, the internal stresses being altered by exposure of the material to radiation to produce altered internal stresses in exposed areas, and exposing the layer of material to radiation to define a pattern, the exposing being performed in associated areas such that the internal stresses within the layer of material and altered internal stresses in the associated areas are substantially offset to reduce distortion in the material system and in the membrane structure.
Generally, this method is used to fabricate X-ray masks with smaller errors, or less distortion, in a pattern.
In a specific example, the method includes forming an etch mask on a layer of X-ray absorbing material including the steps of providing a layer of photoresist sensitive to an electron beam, the photoresist having internal stresses which are altered by exposure to the electron beam, and exposing the photoresist to the electron beam to define a pattern, the exposing being performed in associated areas such that the internal stresses within the photoresist and altered internal stresses in the associated areas are substantially offset to reduce distortion in the etch mask and in the layer of X-ray absorbing material.
Also, in a preferred embodiment, the radiation sensitive material is exposed to radiation to define the chosen pattern by exposing the layer of material in a spiral path starting at approximately a central portion of the layer of material.
This produces a minimum amount of distortion while maintaining maximum patterning speed.