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Secondary ion mass spectrometry depth profiling of boron and antimony deltas in silicon: Comparison of the resolution functions using oxygen bombardment at different energies and impact angles

 

作者: K. Wittmaack,  

 

期刊: Journal of Vacuum Science&Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena  (AIP Available online 1994)
卷期: Volume 12, issue 1  

页码: 258-262

 

ISSN:1071-1023

 

年代: 1994

 

DOI:10.1116/1.587150

 

出版商: American Vacuum Society

 

关键词: DOPING PROFILES;SILICON;BORON ADDITIONS;ANTIMONY ADDITIONS;SIMS;SPATIAL RESOLUTION;ROUGHNESS;ION COLLISIONS;OXYGEN IONS;KEV RANGE 01−10;Si:B;Si:Sb

 

数据来源: AIP

 

摘要:

Codeposited delta doping distributions of B and Sb in Si, with areal densities on the order of 1×1013atoms/cm2, were used to determine the resolution functions for depth profiling of these dopants under 2 and 5 keV O2bombardment at impact angles θ between 0° (normal incidence) and 60°. The resolution functions are described by the first and second moments and by the characteristic inverse slopes, which define the exponential rise and decay of the signal at the profile’s leading and trailing edges, respectively. The decay lengths λd(0°) agree very well with numbers reported recently. The up‐slope parameters λu(0°) are the same for B and Sb (0.65 and 1.0 nm at 2 and 5 keV, respectively), but significantly smaller than the previously published data, which showed differences for B, Sb, and Ge. This discrepancy could be due to differences in roughness of the as‐grown samples. Moreover, the high doping densities used in the previous work might have caused profile distortions during growth. Variations of θ between 0° and 60° have only a very small effect on λu(B, Sb) and on λd(B); e.g., at 5 keV λd(B)=3.3 nm at 0° and 60° with a broad maximum in between, where λd=3.7 nm. By contrast, λd(Sb) is quite large in the range 0°≤θ≤25°, 5.6–6.0 nm, then decreases rapidly with increasing impact angle to fall below λd(B) as θ exceeds 40°. Significant differences between B and Sb are also seen in the first moments 〈z〉 of the resolution function. At 5 keV, e.g., 〈z〉Sb−〈z〉Bvaries from 3.5 nm (0°) to −1.5 nm (60°). The square root of the second moments can be approximated as σ=λu+λd. The difference in the angular dependence of the resolution parameters for B and Sb is thought to be due to differences in the redistribution of the two dopants within the silicon dioxide layer (θ≤25°) and the silicon suboxide (θ≳25°) generated by oxygen bombardment.

 

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