Ultrahigh selective etching of Si3 N4 films over Si O2 films for silicon nitride gate spacer etching

Sunghoon Lee, Jinho Oh, Kyumin Lee, Hyunchul Sohn

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20 Citations (Scopus)


The process window for the high etching selectivity of silicon nitride to silicon oxide was investigated in C F4 /C H4 inductively coupled plasma. This work showed that the etching selectivity could be controlled by modulating the thickness of the fluorocarbon film with the flow rates of C H4 gas. The carbon content in the fluorocarbon by-product layers on the etched films was observed to play a critical role in determining the etching selectivity of silicon nitride to silicon oxide. The increase in the carbon content in the fluorocarbon films with increasing C H4 gas caused the etch rates of both silicon oxide and silicon nitride films to be reduced, eventually leading to the etch stops. The minimum effective thickness of the fluorocarbon films was estimated to be 20 Å for the etch stop. The infinite etching selectivity of the silicon nitride to the silicon oxide on the blanket wafers could be achieved for the C H4 flow rate above 30 SCCM (SCCM denotes cubic centimeters per minute at STP) for the C F4 flow rate of 10 SCCM. N F3 /C H4 and S F6 /C H 4 plasma showed etch behavior similar to C F4 /C H 4 plasma.

Original languageEnglish
Pages (from-to)131-137
Number of pages7
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Issue number1
Publication statusPublished - 2010

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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