Vishal Sipani

Characterization of array CD uniformity with respect to pattern density in 193nm dry photolithography

As we move toward printing sub-100nm features using 193nm dry photolithography with high-contrast photoresists, effects of mask transmission and pattern density start to play an important role in critical dimension uniformity (CDU). With these two factors in existence, the linewidth for a dense feature block gradually increases from the center to the edge of the array of the block. This change in CD is typically observed for low-transmission reticles. In this paper, we have characterized variables, such as reticle tone and resist processing parameters, which have an effect on the CD uniformity. Use of high-contrast photoresist can increase the effect of chemical flare and can have higher CDU. We have further shown that by using a topcoat or by making changes in the resist bake temperature and time, the effect of chemical flare can be reduced. We also propose a mechanism by which resists exhibit this characteristic and show that both the photoacid generator and quencher can contribute to chemical flare.

Fundamental characterization of silicon-containing spin-on hardmask for 193nm photolithography

In this contribution, we have performed the fundamental characterization of silicon-containing spin-on hardmasks. There has been an interest in using these materials as part of multi-layer resist (MLR) technology to replace CVD films in order to improve lithographic performance and lower the overall process cost. However, not much is known about the characteristics of these materials in terms of their resist compatibility and etch performance, based on their composition. We have characterized these materials using a number of analytical techniques, including: FTIR, XPS, etc. We have also studied the effect of numerous etching chemistries, such as CF4 and SO2/O2, to determine their etch characteristics. Finally, we provide some after-dry-develop etch profiles.