Highly Selective SiOC Etch for Advanced Sub-3nm Applications
ABSTRACT
Silicon Oxycarbide (SiOC) is a hybrid low-k dielectric material which comprises between k-values and robustness. It is widely used as inter-metal dielectric (IMD), inter-layer dielectrics (ILD), low-k spacer, etch-stop and barrier layers.
The most common etch chemistry is HF-based etchants, such as dilute HF (DHF) or buffered Oxide Etch (BOE/BHF). Si-O-Si + 6HF → 2H2SiF6 + H2O; or via SiO2 component, SiO2 + 4HF → SiF4+2 H2O. Typical SiOC etch rates of 1:100 DHF range at 30-80 Å/min.
However, DHF and other conventional SiOC etch chemistries (e.g. SC-1 + HF) cannot meet selective SiOC etch for sub-3nm applications with higher SiOC etch rates and expand compatibility requirements (e.g. Si, SiGe, TEOS).
Two novel highly selective SiOC etch chemistries have been recently developed. Acidic non-traditional fluoride-based chemistries (e.g. SSOC-1 and SSOC-2) provide greater than 600Å/min SiOC etch rates and 70-4,000X etch selectivity vs. TEOS, SiGe and Si.
Another types of alkaline-based non-oxidative chemistries (e.g. SSOC-3 and SSOC-4) deliver greater than 800Å/min SiOC etch rates and 90-600X etch selectivity vs. SiGe, TEOS, SiGe and Si.
Selective SiOC etch mechanisms and etchant designs will be discussed in more details.
BIOGRAPHY
Chien-Pin Sherman Hsu, Ph.D., serves as a Technical Fellow, Electronic Materials at Avantor. Current programs at Avantor focus on products for advanced semiconductor technology nodes of 2nm and beyond, including high-performance implant photoresist (PR) strip, residue clean, selective etch, surface preparation and advanced packaging integration. With more than 30 years in research, Dr. Hsu has developed a series of Cu- and low-k-compatible cleaning chemistries and novel techniques that include supercritical fluid cleans in microelectronics and nanoelectronics. His recent work on selective etchants and cleaners provides fine profile tuning, surface conditioning, and integration of a wide range of materials in front-, middle- and back-end-of-line (FEOL, MOL and BEOL) applications. Dr. Hsu received a Ph.D. degree in Chemistry from Cornell University, Ithaca, NY, USA. He has authored more than 60 patents, publications, and conference presentations.