| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS2-WeA |
| Session: | Plasma Surface Interactions during PECVD and Plasma Surface Modification |
| Presenter: | A. Malinowski, Institute of Electron Technology, Poland |
| Authors: | A. Malinowski, Institute of Electron Technology, Poland M. Sekine, Nagoya University, Japan M. Hori, Nagoya University, Japan K. Ishikawa, Nagoya University, Japan H. Kondo, Nagoya University, Japan T. Takeuchi, Nagoya University, Japan T. Suzuki, Nagoya University, Japan A. Jakubowski, Warsaw University of Technology, Poland L. Lukasiak, Warsaw University of Technology, Poland D. Tomaszewski, Institute of Electron Technology, Poland |
| Correspondent: | Click to Email |
As FinFET transistors become necessary, FEOL etch processes will become much more challenging, bringing new constraints to etch selectivity, anisotropy, and etch damage. System-on-a-chip RF and analog devices may have double and triple gates and can be subjected to 12 or more photoresist (PR) removals. Thus development damage-less PR removal is critical for reducing plasma induced transistor electrical parameters fluctuations. In addition to poor uniformity or heavy environmental burden, hydrogen radical-based PR removal is expected to overcome critical problem of damage to the device inborn to currently used PR removal based on oxygen plasmas. As double and “multi” ArF 193nm patterning solutions continue to be a significant vehicle for extending Moore’s Law, it is imperative to investigate plasma-surface interactions between hydrogen radical and chemically amplified ArF 193nm PR. The key element from point of view of etch reaction process kinetics investigation is radical sticking coefficient (SC).
In our study we have developed novel technique for radical SC estimation based on processing of PAPE structure (PAllet for Plasma Evaluation) followed by numerical simulation. Our approach is based on normalized profiles matching of etched PR thickness on parallel plate after PAPE structure processing, using hydrogen high density radical source, with simulated profile of number of stuck radicals on the same plate.
Understanding of the interactions of atomic hydrogen with ArF 193nm PR surface is of both fundamental and technological interest thus recombination mechanism of hydrogen atom on PR surface must be considered. In our approach SC is a sum of etch probability (EP) and recombination probability (RP) and estimated values of EP (0.07) and RP (0.1) reveal fact that recombination dominates during PR etching by hydrogen. Since recombination lowers the number of radicals that are bound to the surface, the reactive species coverage is reduced by this process. Dominance of recombination in conjunction with very low value of EP itself explains very low etch rate, which is on the order of a few nm per minute (it was 3.8 nm/min). In addition similarity of RP obtained in this study and Koleske et al. reveals that the recombination is the result of a gas phase atom abstracting an atom of the same type that has previously chemisorbed to the surface according to the Eley-Rideal mechanism.
Inefficiency of the kinetic energy loss by hydrogen radicals during the PR surface collision, by means of phonon excitation or momentum transfer explains very low value of EP (0.07). Increase of temperature (323 K) of the structure involved proportional increase of EP (0.09).