Defect engineering
Ion implantation and „Defect Engineering“ in Si and SiGe
Ion implantation into crystalline materials such as Si or SiGedamages the crystalline structure.
However, there are also special defects which can be created
locally by ion implantation. Such defects intentionally introduced contribute to:
- recombination of point defects,
- accumulation of foreign atoms,
- excitation of reactions.
This is termed „defect engineering“.
Ion implantation and „Defect Engineering“ in Si and SiGe
Ion implantation generates in Si a typical point defect distribution consisting of excess vacancy defects and –deeper - excess interstitial defects. These defects are responsible for the formation of extended structural defects and trapping of foreign atoms.
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Defect distribution of excess vacancies (Vex) and excess interstitials (Iex) for 2 MeV Ge+ implantation into Si. The blue dots show the depth profile of the Ge+ ions. |
Recent publications:
- Peeva, R. Kögler, W. Skorupa, J.S. Christensen, A.Yu. Kuznetsov, J. Appl. Phys. 95 (2004) 4738
- R. Kögler, A. Peeva, A. Mücklich, F. Eichhorn, W. Skorupa, Appl. Phys. Lett. 88 (2006) 101918
SiGe – a promising material for electronic devices. Adjustments in the composition of the alloy enable to improve the carrier mobility. However, ion implantation generates increasing damage with increasing Ge fraction.
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Defects and depth profile of trapped impurities (Cu) in Si0.8Ge0.2, implanted with 2 MeV Ge+ ions. |
Recent publications:
- R. Kögler, A. Peeva, A.Yu. Kuznetzov, J. Christensen, B.G. Svensson, W. Skorupa, Solid State Phenomena, 95-96 (2004) 587
- R. Kögler, A. Peeva, A. Mücklich, A.Yu. Kuznetzov, J. Christensen, B.G. Svensson, W. Skorupa, J. Appl. Phys. 101 (2007) 033508
Defect engineering for ion beam synthesis
Materials synthesis in the solid state can be initiated or improved by the presence of suitable defects. For instance: vacancy defects assist volume expansive reactions.
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The Simultaneous Dual Beam implantation is a tool simultaneously to perform ion implantation wiht two independent ion beams in a synchronous scanned mode with permanent beam overlap at the target. |
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Recent publications:
- J.R. Kaschny, R. Kögler, H. Tyrrof, W. Bürger, F. Eichhorn, A. Mücklich, C. Serre, W. Skorupa, Facility for simultaneous dual-beam ion implantation, Nucl. Instrum. and Meth. A 551, 200 (2005)
Examples for ion beam synthesis:
► Defect engineering for SIMOX
► Ion beam synthesis of high-K material
Ion beam synthesis of high-k material
Pr2O3 is one of the promising new insulating materials for the next generation of device technology. However, Pr oxide is easily degraded to Pr silicate – a material also of very high k-value compared to SiO2.
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Ternary system Pr-Si-O. Pr oxide (blue), Pr silicide (green), Pr silicate (red). |
Ion beam synthesis results in that composition of the components which is most stable and fits best with the Si substrate.
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| Ion beam synthesized Pr9.33Si6O26 in crystalline Si |
Recent publication:
- R. Kögler, A. Mücklich, F. Eichhorn, M. Posselt, H. Reuther, W. Skorupa, J. Appl. Phys. 100 (2006) 104314
Defect engineering for the initial state of SIMOX processing by simultaneous dual implantation
SIMOX (silicon implanted by oxygen) is a standard technology to produce SOI (silicon on insulator) structures. Such structures are important in the device technology to electrically separate the narrow active surface region from the substrate. SIMOX processing means to create a buried homogeneous oxide layer in Si by high fluence high temperature O implantation.
The oxide formation in Si is volume expansive – and generates strain and defects in the material.
The defect generation can be avoided by introduction of vacancy defects. Such defect engineering assists SIMOX processing.
By simultaneous dual implantation of O and Si ions the excess vacancies generated by the additional Si+ ion beam are applied for vacancy generation.
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Comparison of the conventional single O implantation (low fluence = first stage of the SIMOX process) and of simultaneous O and Si dual implantation under equal conditions. SiO2 islands in defect-free Si (right). |
Recent publication:
- R. Kögler, A. Mücklich, H. Reuther, D. Krecar, H. Hutter, W. Skorupa, Solid State Phenomena 108-109 (2005) 321
