Limiting factors for secondary ion mass spectrometry profiling
作者:
Eun‐Hee Cirlin,
John J. Vajo,
T. C. Hasenberg,
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: 269-275
ISSN:1071-1023
年代: 1994
DOI:10.1116/1.587152
出版商: American Vacuum Society
关键词: SIMS;DOPING PROFILES;SPUTTERING;OXYGEN IONS;KEV RANGE 01−10;ATOMIC FORCE MICROSCOPY;SPATIAL RESOLUTION;SILICON ADDITIONS;GALLIUM ARSENIDES;MONOLAYERS;ALUMINIUM ARSENIDES;TERNARY COMPOUNDS;SUPERLATTICES;INCIDENCE ANGLE;(Al,Ga)As:Si
数据来源: AIP
摘要:
Understanding the limitations of depth profiling with ion sputtering is essential for accurate measurements of atomically abrupt interfaces and ultra‐shallow doping profiles. The effects of cascade mixing, sputtering statistics, ion‐induced roughness, the inhomogeneity of ion beams, and sample rotation on the depth resolution of Si δ‐doped, AlAs, and InAs monolayers in GaAs and an AlGaAs(5 nm)/GaAs(5 nm) superlattice were investigated. Atomic force microscopy (AFM) investigation of the ion‐induced surface ripple formation on a GaAs substrate sputtered with 3 keV O+2at angle of incidence θ=40° showed that ripples form rapidly below 200 nm depth. AFM measured root mean square roughness of Si δ‐doped GaAs sputtered with 2 keV O+2was 0.8 and 2.6 nm with and without sample rotation showing that ripples play a dominant role in depth resolution degradation at shallow depth under these conditions of bombardment. Sample rotation yielded the lowest full width at half‐maximum, 4.1 nm for a Si δ layer at 120 nm depth corresponding to a depth resolution ΔZ=3.5 nm. Use of AFM enabled determination of the atomic mixing ΔZmand sputtering statistics ΔZsscomponents of depth resolution to be identified directly for the first time. These components were 3.1 and 1.5 nm, respectively.
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