Journal of Applied Physics vol:111 issue:11 pages:1-6
A K-and Q-band electron spin resonance (ESR) study has been carried out on (100)Si/SiO2 entities manufactured by low temperature (150 °C) atomic layer deposition (ALD) of a high-quality SiO2 layer on Si using 3-aminopropyltriethoxysilane, H2O, and ozone in a three-step process. Whereas previous work has demonstrated the high quality of the deposited SiO2 layer, the current ESR analysis reports on the tracing of growth-related contamination of near interface Si substrate layers by two transition metals. This includes, first, detection of the signal of interstitial Cr+ (S=5/2) impurities in c-Si, characterized by an isotropic central g value of 1.9980 ± 0.0002, an isotropic 53Cr (I=3/2) hyperfine interaction of splitting Aiso= 11.8 G, and cubic crystal field splitting parameter a=+32.2 G, well in agreement with the known bulk c-Si case. The total Cr+ defect density is inferred as ~5×1011 cm-2. Second, a single signal is observed at isotropic g=2.070 ± 0.001, corresponding to interstitial Fe impurities (Fei)0 (S=1) positioned in a c-Si matrix. Defect density depth profiling reveals the impurities to be confined to a few µm thick Si substrate top layer, the density decaying exponential-like from the Si/SiO2 interface inward the Si substrate. The total of the results points to a contamination of reactor-environment origin, connected with the layer deposition process. It concerns a weak contamination, in which detection the ESR technique emerges as a powerful technique able to unveil very low levels of contamination of near-surface Si substrate layers.