Silicon Etching Study in a RT-CVD Reactor with the HCl/H2 Gas Mixture

Abstract

AbstractA promising candidate to etch silicon totally selective against the dielectrics is here studied. This paper reports a detailed study of the silicon chemical vapor etch with HCl/H2 mixtures. Kinetics measurements on (001)-oriented wafers permitted us to extract apparent activation energies varying from 95.2kcal/mol and 73.9kcal/mol, depending on the HCl dilution in the chamber. On the other hand, etch rates measurements as a function of the HCl partial pressure are found to follow a sub-linear behavior indicating complex mechanisms occurring with the use of the HCl/H2 gas mix. In a second part, thanks to SEM cross-section observations, morphological analysis permitted us to point out that the {311} facet behave differently as compared to the {111} and {100} planes. To conclude, we extracted rugosity data after HCl treatment from AFM measurements and all these results permitted us to validate the potential industrialization of this etching process for the formation of localized cavities or junctions on patterned wafers.