AVS 52nd International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS1-MoA

Invited Paper PS1-MoA5
Polymer Management in Dielectric Etch

Monday, October 31, 2005, 3:20 pm, Room 302

Session: Dielectric Etch I
Presenter: E.A. Hudson, Lam Research Corp.
Authors: E.A. Hudson, Lam Research Corp.
A. Marakhtanov, Lam Research Corp.
K. Takeshita, Lam Research Corp.
Correspondent: Click to Email
Etching of dielectric films for microelectronics requires processes which provide control of feature profiles and high selectivity to mask and stop layer films. For most dielectric films, especially Si-containing materials, plasma etch processes tend to deposit fluorocarbon or hydrofluorocarbon films. These polymeric films play many essential roles, acting to passivate feature sidewalls, to control critical dimensions and profile angles, to reduce mask loss, to minimize corner faceting, and/or to protect underlayers. But polymer deposition on reactor surfaces can lead to difficulties in maintaining stable reactor conditions. This paper focuses on several critical areas in dielectric etch processing where understanding and managing the behavior of deposited polymer is crucial. One focus is the effect of polymer upon microscopic structures. For example, low-k dielectric films tend to be modified by photoresist removal processes. Protective sidewall films have shown the capability to limit strip-induced damage. In another example, fluorocarbon films prepared under simulated conditions for sidewall vs top surfaces have shown different properties. These differences can influence final etch profiles. Another focus is the behavior of polymer on reactor surfaces. Multi-step in-situ processing has become a standard production method for reducing cost and cycle time. To maintain a stable process, it is important to understand how the chamber condition evolves during the sequential etch steps, and to minimize the interaction between these steps. Several process and plasma parameters influence the measured deposition rate of polymer on reactor surfaces. For transitions from a polymerizing step to a step which can etch polymer, the plasma conditions and process results may be influenced by the removal of residual chamber polymer. Time-resolved plasma measurements show the extent of this step-to-step chamber memory effect, and how it can be minimized.