AVS 50th International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS1-ThM

Paper PS1-ThM9
Study of Fluorocarbon Deposition Mechanism with a Small Gap Structure in Fluorocarbon Plasmas

Thursday, November 6, 2003, 11:00 am, Room 314

Session: Plasma-Surface Interactions: Deposition
Presenter: L. Zheng, University of Maryland, College Park
Authors: L. Zheng, University of Maryland, College Park
X. Li, University of Maryland, College Park
X. Hua, University of Maryland, College Park
L. Ling, University of Maryland, College Park
G.S. Oehrlein, University of Maryland, College Park
E.A. Hudson, Lam Research Corp.
Correspondent: Click to Email
We designed a small gap structure to study the deposition of fluorocarbon film in a high aspect ratio feature in an inductively coupled rf plasma (ICP) reactor in an effort to provide information on fluorocarbon film formation mechanisms for highly selective dielectric etching processes. The small gap structure exhibits three regions for fluorocarbon film formation: A region exposed to the full plasma, transition region and a completely shadowed region where only long-lived species can arrive after multiple collisions with the walls. Both in situ (real time) and external He-Ne ellipsometers were used to monitor the deposition rate of the fluorocarbon film on the base wafer. X-ray photoelectron spectroscopy (XPS) was used to analyze the detailed surface chemistry of the fluorocarbon film. CFx (x = 1-3) radicals produced in fluorocarbon discharges act as precursors for the formation of fluorocarbon film. Effects of different gases (C4F8, C4F6), Ar addition, gap height, pressure on refract index and deposition rate of the fluorocarbon film in the three regions were studied and a simple model based on Knudsen diffusion mechanism was developed to describe the fluorocarbon film deposition in the completely shadowed region. We also will describe an equivalent set of studies performed in a 40 MHz (source power) - 13.56 MHz RF (bias power) dual frequency capacitively coupled system.