AVS 51st International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThA

Paper PS-ThA1
A Comprehensive Study of Gas Phase and Plasma-Surface Interactions of Depositing Fluorocarbon Plasma Systems

Thursday, November 18, 2004, 2:00 pm, Room 213A

Session: Plasma-Surface Interaction
Presenter: I.T. Martin, Colorado State University
Authors: I.T. Martin, Colorado State University
E.R. Fisher, Colorado State University
Correspondent: Click to Email
A thorough investigation of the gas-phase chemistry, plasma-surface interactions, and surface properties of deposited materials has been performed for C@sub 3@F@sub 8@ and C@sub 4@F@sub 8@ plasmas. OES-actinometry, LIF and MS were used to study the plasma gas phase. OES quantifies excited state species in these systems, whereas LIF measurements provide relative densities of ground state CFx species as a function of applied rf power (P) and pressure. CF LIF excitation spectra were used to measure CF rotational temperatures (@Theta@@sub R@) as a function of P and pressure: @Theta@@sub R@(CF) in C@sub 4@F@sub 8@ plasmas is approximately constant over a range of P and pressure, whereas it increases with P in the C@sub 3@F@sub 8@ systems. MS data identify nascent ions and measure ion energy distributions. Plasma-surface interactions of CFx species were investigated using our Imaging of Radicals Interacting with Surfaces (IRIS) molecular beam apparatus. CF@sub 2@ surface production was characterized during C@sub 3@F@sub 8@ and C@sub 4@F@sub 8@ plasma processing of Si via a scattering coefficient, S(CF@sub 2@), the ratio of CF@sub 2@ molecules scattering from the surface relative to those in the molecular beam. S(CF@sub 2@) values>1 were measured during the deposition of amorphous fluorocarbon (FC) materials. This net surface production of CF@sub 2@ suggests that CF@sub 2@ is not a deposition precursor in these FC systems. Charged species contribute to CF@sub 2@ surface production, as demonstrated by the decrease in S(CF@sub 2@) measured under ion-limited conditions. A notable result of this work is the positive correlation between S(CF@sub 2@) and %-crosslinking measured by XPS in the deposited FC materials. Optimized FC materials were used in several applications, including the production of micropatterned surfaces used in cell growth studies, and the modification of microfluidic devices. The performance of our FC materials in these applications will be discussed.