Atomic layer deposited dopant oxide films for doping of germanium and silicon-germanium substrates: Deposition – Flash Lamp Annealing – SIMS metrology

• Applicants: Professor Dr.-Ing. Edmund P. Burte; Professor Dr. Andreas Mai; Dr. Lars Rebohle
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Synthesis and Properties of Functional Materials
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 397771392

• Final Report Year: 2022

Final Report Abstract

The objective of the project was the development of a doping process for planar and nanostructured SiGe and Ge surfaces, which is based on atomic layer deposition (ALD) and a subsequent flash lamp annealing (FLA). The deposited ALD layers contained boron, phosphorous, and antimony, and served as a dopant source, whereas FLA was used to drive-in and to activate the dopants in regions close to the surface of the SiGe and Ge substrates. The suitability of the investigated ALD layers was quite different. Boron oxide layers strongly decomposed when exposed to air, and even the use of capping layers could not solve this problem. The stability of phosphorouscontaining layers was better under air exposure, but required the partial use of Al2O3 capping layers. Thereby, P3N5 layers turned out to be the most stable ones. Layers made of antimony or antimony monoxide have proven to be stable without the need of capping layers. FLA was applied with pulse times of 3 and 6 ms, and in a temperature range of 950 and 1200 K. This has led to an in-diffusion of dopants with penetration depths between 4 and 7 nm for antimony and 10 to 40 nm for phosphorous. As expected, longer pulse times and higher temperatures led to larger penetration depths. In case of antimony, an activation degree between 4 and 7% was found by combining the results of secondary ion mass spectroscopy and scanning spreading resistance microscopy. In case of antimony and phosphorous, a doping process for planar and nanostructured SiGe and Ge surfaces was developed. Because of unexpected challenges in preparation, this process could not be tested on real active devices. However, the obtained results can be used to develop adapted MOS test devices with larger gate lengths and reduced auxiliary structures for lithography, so-called dummy gates. This in turn would allow the fabrication of an active MOS transistor on a SiGe substrate.

Publications

• Formation of Thin NiGe Films by Magnetron Sputtering and Flash Lamp Annealing, Nanomaterials 2020, 10, 648
  V. Begeza, E. Mehner, H. Stöcker, Y. Xie, A. García, R. Hübner, D. Erb, S. Zhou, L. Rebohle