AVS 49th International Symposium
    Plasma Science Monday Sessions
       Session PS1-MoA

Paper PS1-MoA6
Silicon Oxide Highly Selective Etching Using Novel Solid Gas Sources

Monday, November 4, 2002, 3:40 pm, Room C-103

Session: Dielectric Etch I
Presenter: M. Nagai, Nagoya University, Japan
Authors: M. Nagai, Nagoya University, Japan
M. Hori, Nagoya University, Japan
T. Goto, Nagoya University, Japan
Correspondent: Click to Email
Dry etching of silicon oxide (SiO@sub 2@) films is an essential process for fabricating deep contact holes in ultralarge-scale integrated circuits (ULSIs). This process has been developed by using high density plasma employing perfluorinated compound (PFC) gases such as CF@sub 4@, CHF@sub 3@, C@sub 2@F@sub 6@, C@sub 4@F@sub 8@, and so on. In this process, the high selectivity of SiO@sub 2@ over resist and underlayers and the vertical etching profile for high aspect ratio patterns are required. However, there has been a problem of the poor SiO@sub 2@/resist selectivity using PFC gas source. Additionally, PFC gases of high global warming potential cause a serious environmental problem. In this study, we have developed an environmentally begin etching process without PFC gases which enables to control the radicals independently, for example CF@sub 2@ radical, C atom and F atom. In this system, the etching was performed with magnetron plasma source. The top electrode of graphite was supplied with two rf powers of 13.56 MHz and 450 kHz, which were separated through a low-pass filter. The plasma was generated by 13.56 MHz and the incident ion energy on the graphite target was controlled by 450 kHz. The bottom electrode was supplied with rf power of 2 MHz as the substrate bias. Fluorine and carbon atom sources were employed instead of PFC gases. Ar and F@sub 2@ gases as a fluorine atom source were injected into the process chamber. Carbon species were generated by magnetron sputtering of the graphite plate using Ar and F@sub 2@ gas plasma. In this etching system, the etching characteristics of SiO@sub 2@ and resist were investigated. As a result, by controlling the carbon and fluorine species incident on the surface, we have obtained the SiO@sub 2@ etching rate of 420 nm/min and high SiO@sub 2@/resist selectivity of 10 with good pattern profile of the contact holes in environmentally begin etching system without employing PFC gases.