Observation of Microscopic Nonuniformity during Overetch in Polysilicon Gate Etching
- 1 April 1997
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 36 (4B) , L518-521
- https://doi.org/10.1143/jjap.36.l518
Abstract
Microscopic uniformity during overetch has been investigated for polysilicon gate etching in electron cyclotron resonance Cl2/O2 plasmas, using atomic force microscopy as well as scanning electron microscopy. As the O2 percentage was increased in Cl2/O2 plasmas, the aspect-ratio dependence of the poly-Si etch rate changed from a weak reactive-ion-etching (RIE) lag to a slightly inverse RIE lag; on the other hand, the aspect-ratio dependence of the SiO2 etch rate exhibited a strongly inverse RIE lag at high O2 percentages. As a result, the microscopic etch selectivity of poly-Si over SiO2 was considerably degraded with increasing aspect ratio, giving rise to gate oxides broken in large aspect-ratio features during overetch. These results are indicative of the transport of incoming oxygen atoms in microstructures limited by neutral shadowing.Keywords
This publication has 8 references indexed in Scilit:
- Numerical study of the etch anisotropy in low-pressure, high-density plasma etchingJournal of Applied Physics, 1997
- Profile Evolution during Pulsed Plasma EtchingJapanese Journal of Applied Physics, 1996
- Effects of etch products and surface oxidation on profile evolution during electron cyclotron resonance plasma etching of poly-SiJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1996
- Aspect Ratio Independent Etching: Fact or Fantasy?Japanese Journal of Applied Physics, 1995
- Scaling of Si and GaAs trench etch rates with aspect ratio, feature width, and substrate temperatureJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1995
- Influence of Reaction Products on Si Gate Etching with a Photoresist Mask in HBr/O2 and Cl2/O2 Electron Cyclotron Resonance PlasmaJapanese Journal of Applied Physics, 1993
- Microscopic uniformity in plasma etchingJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1992
- Radio frequency plasma etching of Si/SiO2 by Cl2/O2 : Improvements resulting from the time modulation of the processing gasesJournal of Vacuum Science & Technology B, 1990