Kinetics and coupled dynamics of dewetting and chemical reaction in Si/$$\hbox {SiO}_2$$/Si system

Abstract

We report on the observation of a coupling between the dewetting of a Si layer on $$\hbox {SiO}_{{2}}$$ induced by surface/interface energy minimization and the etching between both materials due to the $$\hbox {Si}+\hbox {SiO}_{2}\longrightarrow 2$$ $$\hbox {SiO}^\uparrow _g$$ reaction. In the limit of a thin $$\hbox {SiO}_{{2}}$$ layer ( $$\le 10 \,\hbox {nm}$$ ) sandwiched between a Si layer and a Si handle wafer, the front of Si dewetting and the front of $$\hbox {SiO}_{{2}}$$ etching coexist in a narrow region. The interplay between both phenomena gives rise to specific morphologies. We show that extended Si fingers formed by dewetting are stabilized with respect to Rayleigh–Plateau-type instability over tenth of microns thanks to a localized etching of the $$\hbox {SiO}_{{2}}$$ layer. The breakup of this structure occurs abruptly by an unzipping process combining dewetting and etching phenomena. We also put in evidence that Si rings are created with a thin $$\hbox {SiO}_{{2}}$$ layer in the center. These processes are thermally activated with an activation energy of $$2.4\pm 0.5 \,\hbox {eV}$$ and $$4.0\pm 0.5 \,\hbox {eV}$$ , respectively, for dewetting and the etching reaction. All these results highlight the respective roles of wetting and etching in Si/ $$\hbox {SiO}_{{2}}$$ /Si system dynamics and could be a stepping stone for the development of advanced processes based on Silicon-On-Insulator technology.