Resist patterning for sub-quarter-micrometer device fabrications (Invited Paper)

Abstract

In the fabrication of sub-quarter micron devices, the key components needed to realize this task must be fully integrated. The lithography capability and subsequent device processing control must be understood by the device designers and the device technology area as well. One such ingredient in this integrated operation is a high-resolution electron beam lithography sector which encompasses both resist process control and exposure tool capability. A high- throughput variable shape beam system operating at 50 keV provides both the resolution and overlay required at 0.25 μm. However, for 0.1 μm structures and below, a thermal field emission Gaussian beam system is used. This paper reports on the application of various resist systems in the fabrication of these experimental devices. Conventional resists like diazonaphthoquinone novolac based resists have been successfully applied a single-layer resist systems in the patterning of the contact and deep trench levels down to 0.20 μm. For negative tone imaging, an epoxy crosslinking resist based on chemical amplification has been successfully used to pattern poly gates down to 0.10 μm with vertical walls. This negative resist was also used as a thick single-layer resist system in implant levels where vertical resist walls are essential. Furthermore, 0.25 μm lines in single layer resist over 0.4 μm steps were resolved with no evidence on linewidth distortions.