PFC Emission Control Options for Plasma Processing Tools: A Current Assessment

Abstract

Perfluorocompounds (PFCs) are critical processing gases for a number of plasma-based IC processing steps, especially dry etching and in situ CVD chamber cleaning. The long atmospheric lifetimes and large infrared absorption cross sections for such gases (which include CF4, C2F6, C3F8, NF3, SF6, and CHF3) have raised concerns about the contributions of PFC emissions to possible global warming. Global regulatory policies on greenhouse gases are expected to include the PFCs, and the specific attention given to these gases in negotiations between the U.S. government and the semiconductor industry may expand internationally as well.Several options exist for PFC emission control, including process optimization, chemical substitution, capture/recovery/recycle, and destructive abatement (including combustion, reactive adsorption, and plasma decomposition). An assessment of each option will be made in terms of both technical effectiveness (i.e., PFC reduction achievable) as well as implementation issues (e.g., commercialization timing, cost of ownership). PFC users can expect to have several commercial options to choose from to meet future PFC emission control requirements.

Dry Etching Performance and Gas-Phase Parameters of C6F12O + Ar Plasma in Comparison with CF4 + Ar

“…The increasing attention to the environmental pollution issue has motivated intensive studies of eco-friendly dry etching processes [22,23]. Particularly, it was suggested to substitute conventional process chemistries based on high-GWP fluorocarbon gases for alternate ones with lower environmental impacts [24,25]. One of the possible candidates here is the dodecafluorooxepane (C 6 F 12 O) which exhibits low GWP index of 1, has the extremely low toxicity, as well as is featured by the boiling point above the room temperature [26].…”

Plasma Parameters and Etching Characteristics of SiOxNy Films in CF4 + O2 + X (X = C4F8 or CF2Br2) Gas Mixtures

“…Recently, environmental pollution and resource consumption have received increasing attention in the semiconductor industry, and several studies on the eco-friendly manufacturing processes have been conducted [24,25]. One way for improving the situation is to replace conventional high-GWP process chemistries with those that exhibit a reduced environmental impact [26,27]. That is why several low-GWP fluorocarbon compounds have been tested for application in plasma-assisted etching processes [28][29][30].…”

Reaction Mechanisms in Both a CHF3/O2/Ar and CHF3/H2/Ar Radio Frequency Plasma Environment

“…Fluorocompounds (FCs) were most known as fire suppressants, , chemical extinguishers and ozone-depleting substances. , Today, various FCs have been applied in the semiconductor industry, such as chemical vapor deposition (CVD) techniques , and chemical-etching processes. , Typically, gaseous effluents which contained various FCs emitting from these processes were diluted with vast quantities of air or nitrogen and were either released into the atmosphere or thermally incinerated . Some FCs are atmospherically long-lived, strong infrared absorbers, and thermally stable …”

“…Great attention has been focused on the control and reduction of perfluorocompounds (PFCs) emissions, especially for the semiconductor industry. The control technologies of PFCs emissions include process optimization, PFC replacement, PFC capture/recovery, and destructive abatement . In general, the CVD processes or the dry-etching processes are typically parameter-adjusted and end-pointed to meet the regulated requirements, and there may be little opportunity to further optimize the processes to reduce the PFCs emissions …”

“…In general, the CVD processes or the dry-etching processes are typically parameter-adjusted and end-pointed to meet the regulated requirements, and there may be little opportunity to further optimize the processes to reduce the PFCs emissions . But the exhausts containing HF and SiF 4 chemically degraded the membrane and particulates presented in the stream physically blocked the pore sites.…”