AVS 47th International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS2-MoA

Paper PS2-MoA2
Fabrication of 80 nm PN-poly/metal Gate on Ultra-thin 1.5 nm Oxynitride

Monday, October 2, 2000, 2:20 pm, Room 311

Session: Plasma Etching of Conductors
Presenter: K. Kinoshita, NEC Corporation, Japan
Authors: K. Kinoshita, NEC Corporation, Japan
S. Saito, NEC Corporation, Japan
Y. Saito, NEC Corporation, Japan
M. Narihiro, NEC Corporation, Japan
M. Ueki, NEC Corporation, Japan
H. Wakabayashi, NEC Corporation, Japan
Y. Ochiai, NEC Corporation, Japan
T. Mogami, NEC Corporation, Japan
Y. Hayashi, NEC Corporation, Japan
Correspondent: Click to Email
A PN-poly/metal gate is thought to be the promising technology to embedded LSIs beyond 0.13 µm design rule. This paper describes about the 80 nm PN-poly/metal gate fabrication technique on ultra-thin 1.5 nm gate oxynitride. Mix & match resist pattern by a point-beam EB system (JEOL, JBX-9300FS) for sub-0.1 µm pattern, and a usual KrF lithography system for wider pattern were developed over CVD-SiO@sub 2@/W/barrier/PN-poly-Si/gate-oxynitride stack on "8 wafer. The resist mask was transferred to CVD-SiO@sub 2@ hard mask layer, and then the poly/metal stack etching were investigated with a single chamber of an ICP type etcher (AMAT, Silicon Etch Centura DPS). The use of N@sub 2@-rich N@sub 2@/SF@sub 6@/Ar gas system for W etching, and the use of HBr/Cl@sub 2@/O@sub 2@ gas system for TiN etching generated rectangular cross section. Then, the PN-Poly-Si layer was etched by HBr/O@sub 2@ gas system. There existed the important correlation between relative oxygen density change by an optical actinometry and the PN-poly-Si etching. As the O@sub 2@ flow increased, the oxygen density increased, and the local etching to the silicon substrate through the thin gate oxynitride effectively suppressed. However, the excess O@sub 2@ flow brought etching stop on P-poly-Si region. XPS analysis for the etched P-Si wafer showed that the thicker oxide formation on the P-Si wafer etched at the etching stop condition. These results indicated that the P-Si surface oxidation brought both the high etching selectivity and the etching stop. The thinner the gate oxynitride, the narrower the process margins. Finally, good device characteristics were achieved.