Ion projection lithography below 70 nm: tool performance and resist process
Ion projection lithography (IPL) uses electrostatic ion-optics for reduction printing of stencil mask patterns to wafer substrates. The IPL process development tool (PDT) prints field sizes of 12.5 mm12.5 mm (wafer) at a demagnification factor of 4. First printing results demonstrating different aspects such as resolution, linearity, exposure schemes with stencil masks and image stabilization are available. As an integral part of IPL a resist process suitable for 50 nm minimum feature size has been established using the IMS 1:1 ion beam proximity exposure tool. This resist process has been transferred successfully to the PDT. Compared to previous experiments, sensitivity and contrast have been determined for a larger number of resist materials and with higher precision. Improved resist patterns, better CD linearity and higher stability with respect to pattern collapse have been achieved by optimizing the process parameters. For a Shipley resist, system input parameters for simulations have been determined. Results for the quantum efficiency obtained by Szmandas titration method will be presented.
ion projection lithography lithography resist process