AVS 51st International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS1-TuM

Paper PS1-TuM7
Study on Self-aligned Contact Oxide Etching Using C@sub 5@F@sub 8@/O@sub 2@/Ar and C@sub 5@F@sub 8@/O@sub 2@/Ar/CH@sub 2@F@sub 2@ Plasma

Tuesday, November 16, 2004, 10:20 am, Room 213A

Session: Dielectric Etching
Presenter: S.B. Kim, Hynix Semiconductor Inc., Korea
Authors: S.B. Kim, Hynix Semiconductor Inc., Korea
D.G. Choi, Hynix Semiconductor Inc., Korea
D.S. Kim, Hynix Semiconductor Inc., Korea
Y.W. Song, Hynix Semiconductor Inc., Korea
C.I. Kim, Chung-ang University, Korea
Correspondent: Click to Email
A self-aligned contact (SAC) technology is developed for application of electrical contacts between the local interconnection and the silicon diffusion regions (or plug pad) from 0.18µm device. The commercial memory devices have capping (or spacers) nitride (Si@sub 3@N@sub 4@) for protection of Word Line (or Bit Line) and nitride thin film layer for etching stop of SAC. Recently, the problems of SAC etch process in ULSI devices of sub 0.1µm-design rule are low selectivity to nitride and etching-stop due to high aspect ratio of contact hole. The key issue of SAC etch process is control of polymer generation. In this study, the characterizations of SAC oxide etching are investigated with C@sub 5@F@sub 8@/O@sub 2@/Ar and C@sub 5@F@sub 8@/O@sub 2@/Ar/CH@sub 2@F@sub 2@ plasma. As the mixing ratio of O@sub 2@ on the C@sub 5@F@sub 8@/Ar/O@sub 2@ increase, the amount of polymer decreases and the ability of contact etching increases, the effect CH@sub 2@F@sub 2@ addition on SAC oxide (SiO@sub 2@) etching in C@sub 5@F@sub 8@/Ar/O@sub 2@ is that etch rate of oxide in the contact hole increases about 7%, and the selectivity of oxide to nitride increase, specially that to nitride of contact bottom for SAC etch stopping increases. The selectivity of oxide to nitride increases with increasing of plasma source power or with decreasing of bias power. SAC patterned wafers were characterized using top-down critical dimension scanning electron microscopy (CD-SEM), cross-section SEM, and transmission electron microscopy (TEM). To analyze the effect of various parameters on the C@sub 5@F@sub 8@/Ar plasmas, we investigated the chemical species in the gas phase with an optical emission spectroscopy (OES). The components of polymer were investigated with transition electron microscopy - energy dispersive X-ray (TEM-EDX) and auger electron spectroscopy (AES). X-ray photoelectron spectroscopy (XPS) studies have analysis of real polymer topology on contact bottom and side wall.