[PDF]    http://dx.doi.org/10.3952/lithjphys.45205

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 45, 125–131 (2005)


SIMULATION OF SILICON ETCHING IN CF2Cl2 PLASMA
R. Knizikevičius
Department of Physics, Kaunas University of Technology, K. Donelaičio 73, LT-44029 Kaunas, Lithuania
E-mail: rimantas.knizikevicius@ktu.lt

Received 7 March 2005

The reactive ion etching of silicon in CF2Cl2 plasma is considered. The profiles of etched trenches are calculated as the functions of mask dimensions, flux of CF2 radicals, and parameters of ion bombardment. The processes of adsorption, activation, chemical reactions, relaxation, desorption, and sputtering are included in the proposed model. During one-dimensional etching, F/C ratio of adsorbed layer decreases with the intensification of reaction of CF2 radicals with Si atoms and of the sputtering of polymer and SiC molecules. The values of frequency probabilities, found by extrapolation from the experimentally measured one-dimensional silicon etching rate in CF2Cl22 plasma, are used for the calculation of the real dimensions of etched trenches. During two-dimensional etching, F/C ratio in the trench bottom depends on the fluxes of neutrals and ions. F/C ratio at the sidewalls is equal to 2. Special attention is given to the etching anisotropy and lateral etching. The influence of the ratio of concentration of CF2 radicals and concentration of CF2+ ions in the plasma on an etched trench profile is considered. The conditions under which anisotropic etching prevails are found.
Keywords: CF2Cl2 plasma, silicon, reactive ion etching
PACS: 52.77.Bn, 82.35.Gh, 82.65.+r


SILICIO ĖSDINIMO CF2Cl2 PLAZMOJE MODELIAVIMAS
R. Knizikevičius
Kauno technologijos universitetas, Kaunas, Lietuva

Išnagrinėtas reaktyvus joninis silicio ėsdinimas CF2Cl2 plazmoje. Išėsdintų kanalų profiliai apskaičiuoti kaip kaukės matmenų, CF2 radikalų srauto ir joninio apšaudymo parametrų funkcija. Pasiūlytame modelyje atsižvelgta į įgerties, aktyvavimo, cheminių reakcijų, relaksacijos, atvirkštinės gerties ir dulkėjimo vyksmus. Vienmačio ėsdinimo metu įgerto sluoksnio F/C santykis mažėja, intensyvėjant CF2 radikalų reakcijai su Si atomais, polimero ir SiC molekulių dulkėjimui. Dažninių tikimybių vertės, rastos ekstrapoliuojant eksperimentiškai išmatuotas silicio vienmačio ėsdinimo spartas CF2Cl2 plazmoje, panaudotos išėsdintų kanalų realiems matmenims skaičiuoti. Dvimačio ėsdinimo metu F/C santykis kanalo dugne priklauso nuo neutralių ir joninių srautų. F/C santykis šoninėje sienelėje lygus 2. Atkreiptas dėmesys į ėsdinimo anizotropiją ir šoninį ėsdinimą. Tirta CF2 radikalų ir CF+2 jonų koncentracijų santykio plazmoje įtaka išėsdinto kanalo profiliui. Rasta, kokiomis sąlygomis vyrauja anizotropinis ėsdinimas.


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