Development of 3-D Microfabrication Method by SR Lithography

PMMA(Polymethyl Methacrylate)microstructures fabricated by X-ray lithography with plane-pattern to cross- section transfers technique has a direct influent from the absorber on X-ray mask pattern.Due to the dependency between the absorbed X-ray energy distribution in PMMA and the shape of absorber on the X-ray mask,without the compensation for mask design,the deformed shapes of sloped side-wall on the exposed structures are observed.The factors causing the de- formation are investitated.The effect of dose-depth nonlinear curve is the most possible cause of the problem.Based on the measurement of errors occurred between the 2-D shape of mask pattern and the resulting wall of fabricated 3-D structure,the strength of microneedle is improved by changing the mask pattern from a double right-triangular pattern to a double semi-cir- cular pattern.Moreover,in order to clarify the practical error,we have developed a useful graphical data of the structural profiles versus absorbed X-ray energy.