Fluorocarbon radical density measurements in an inductively coupled plasma reactor

Infrared absorption spectroscopy was used to determine [CF] and [CF ₂] time evolutions and CF₂ rotational temperature in inductively coupled pulsed plasmas. From modeling the time evolutions we determined that CF molecules are generated by ion bombardment of polymer covered surfaces and are consumed in a first order homogeneous process. No single model adequately describes [CF₂] time evolution while the plasma is on. [CF ₂] shows near-first order exponential decay. Hydrogen addition to the plasma increases [CF] and [CF₂] decay time. A C atom balance was developed based on decay data and generation and loss mechanisms determined from the time evolutions.; We deposited fluorocarbon polymer on bare Si wafers while monitoring deposition rate, gas-phase chemistry, and ion current and determined that polymer deposition is due to direct incorporation of CF molecules and ion-dependent incorporation of CF₂ molecules. The ion-dependent CF₂ term was 2 modified to reflect a saturation effect at high [CF₂]. Using the polymer deposition model, we determined sticking coefficients for CF and CF₂ molecules.; Oxide and photoresist etch rates and etch selectivity were explored in the parameter space near etch stop and the parameter space at high bias to minimize polymer deposition. Conditions that provide high oxide etch rates generally result in low selectivity. For the design with the parameter space near etch stop, etch rates and selectivity were modeled using an ion energy-dependent etch rate model that incorporates the etch-impeding effect of fluorocarbon polymer. Polymer thickness was predicted by balancing generation and loss mechanisms. For the design with the parameter space at high bias to minimize polymer deposition, etch rate was modeled as the product of a constant, I _sat and V_bias1/2. This model is similar to the ion energy-dependent etch rate model with no polymer to impede etching.; We compared Ar actinometry to infrared absorption spectroscopy for measurement of [CF] and [CF₂]. Ar actinometry is applicable for [CF] measurement at a given pressure using CF₄ and C₂F₆ feed gases, but not among different pressures. Ar actinometry is suitable for [CF ₂] measurement for all process conditions using CF₄, CHF ₃, and C₂F₆ feed gases.