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A Benchmark of 300mm RP-CVD Chambers for the Low Temperature Epitaxy of Si and SiGe
摘要： we have assessed, in 300 mm Reduced Pressure – Chemical Vapour Deposition chambers from major suppliers, the advantages and drawbacks of disilane for the low temperature growth of Si and SiGe. Si growth rates are, for T < 575°C, approximately ten times higher with Si2H6 than with SiH4, which are in turn roughly ten times higher than with SiH2Cl2. For given GeH4 and Si precursor mass-flow ratios, lower Ge contents and much higher SiGe growth rates are obtained at 550°C, 20 Torr with Si2H6 than with SiH4 and especially SiH2Cl2. Growth rates (Ge concentrations) are with SiH4 and SiH2Cl2 lower (slightly lower) in Supplier A than in Supplier B chamber. The situation is the opposite with Si2H6. This is assigned to (i) a ~ 5°C offset between the two and (ii) effective precursor flows which are different, most likely due to chamber geometry differences. Growth rate activation energies and relationships linking Ge concentration to precursor mass-flow ratios are quite similar, however, making process transfer between the two rather easy. Finally, we have compared ex-situ “HF-Last” wet cleanings and in-situ surface preparation processes for Si surface conditioning prior to epitaxy. Surfaces are after the latter always under high purity N2. This results in a threshold H2 bake temperature (above which there is no O interfacial contamination anymore) which is shifted downwards by ~ 25°C (from 775°C down to 750°C). Below that threshold, O sheet concentrations are with in-situ processes typically one third those associated with “HF-Last” wet cleanings and epitaxial surfaces are smoother.
关键词： surface preparation,SiGe,silane,disilane,RP-CVD,low temperature growth,Si,dichlorosilane
更新于2025-09-23 15:21:01
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Theoretical evaluation of thermal decomposition of dichlorosilane for plasma-enhanced atomic layer deposition of silicon nitride: the important role of surface hydrogen
摘要： Silicon nitride (SiN) thin films have been widely employed for various applications including microelectronics, but their deposition presents a challenge especially when highly conformal layers are necessary on nanoscale features with high aspect ratios. Plasma-enhanced atomic layer deposition (PEALD) has been demonstrated to be a promising technique for controlled growth of SiN thin films at relatively low temperatures (o400 1C), in which thermal decomposition of Si-containing precursors on a N-rich surface is a critical step. Based on periodic density functional theory calculations, we present potential underlying mechanisms leading to facile thermal decomposition of dichlorosilane (DCS, SiH2Cl2) on the N-rich b-Si3N4(0001) surface. Our study highlights the importance of high hydrogen content on the N-rich surface, rendering primary and secondary amine groups. When the N-rich b-Si3N4(0001) surface is fully hydrogenated, the molecular adsorption of DCS is predicted to be exothermic by 0.6 eV. In this case, DCS decomposition appears to be initiated by nucleophilic attack by an amine lone-pair on the electrophilic Si, leading to the formation of a DCS-amine adduct intermediate followed by release of a Cl(cid:2) anion and a proton. The predicted activation barrier for the DCS decomposition reaction is only 0.3 eV or less, depending on its adsorption configuration. We also discuss the formation and desorption of HCl, the subsequent formation and nature of Si–N bonds, and the interaction between adsorbed DCS molecules. While clearly demonstrating the advantageous features of DCS as a Si precursor, this work suggests that the thermal decomposition of Si precursors, and in turn the ALD kinetics and resulting film quality, can be strongly influenced by surface functional groups, in addition to product accumulation and precursor coverage.
关键词： silicon nitride,plasma-enhanced atomic layer deposition,dichlorosilane,surface hydrogen,thermal decomposition,density functional theory
更新于2025-09-19 17:15:36