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6590628 
Journal Article 
Mass spectrometry analysis of the plasma-walls interaction during silicon gate etching in HBr/Cl2/O2 and CF4 plasmas 
Cunge, G; Joubert, O; Sadeghi, N; Vallier, L 
2002 
179-80 vol.1 
INSPEC:7991629 
The plasma surface interaction in different plasma chemistries used for silicon gates etching (HBr, Cl2 and their mixture with O2 and CF4) has been studied by mass spectrometry. By varying the plasma external control parameters (RF bias and initial chemistry), it is possible to distinguish between the reactive species surface loss (or production) mechanisms occurring at the wafer surface and those taking place at the reactor walls. As a result, we will show that the growth mechanism of the SiO-CFx layer (that is continuously depositing on the reactor walls) is strongly influencing the gas phase concentration of several reactive species. The layer deposition consumes SiClXBrY etch products (which are subsequently oxidized and incorporated in the film) and O atoms, and at the same time it releases Br atoms in the gas phase. Finally we will show that the chemical nature of the layer (i.e. the ratio SiOX/CFX in this layer) modifies dramatically the recombination rate of Cl and Br atoms and thus their gas phase concentration.