Surface acoustic wave diagnosis of vacancy orbital with electric quadrupoles in silicon

International Conference on Strongly Correlated Electron Systems 2014

Goto, T.^1 ; Mitsumoto, K.^1 ; Akatsu, M.^1 ; Baba, S.^1 ; Okabe, K.^1,3 ; Takasu, R.^1 ; Nemoto, Y.^1 ; Yamada-Kaneta, H.^2 ; Furumura, Y.^4 ; Saito, H.^3 ; Kashima, K.^3 ; Saito, Y.^5

Graduate School of Science and Technology, Niigata

950-2181, Japan^1

Department of Electrical Engineering and Electronics, Kyushu Institute of Technology, Kitakyushyu

804-8550, Japan^2

GlobalWafers Japan Co., Ltd., Seiro, Niigata

957-0197, Japan^3

Philtech Inc., Bunkyo, Tokyo

113-0033, Japan^4

Toshiba Corporation, Yokohama

225-8522, Japan^5

关键词: Boron-doped silicon;    Electric quadrupoles;    Interdigital transducer;    Low temperatures;    Strain interactions;    Surface acoustic wave (SAW);    Surface acoustic waves;    Vacancy concentration;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/592/1/012150/pdf
DOI  :  10.1088/1742-6596/592/1/012150

来源: IOP

【 摘 要 】

We demonstrate ultrasonic diagnosis of vacancies in boron-doped silicon wafers currently used in device manufacturing. The low-temperature softening of elastic constants measured by surface acoustic waves (SAW) as well as bulk ultrasonic waves is caused by a coupling of elastic strains to electric quadrupoles of the vacancy orbital in silicon wafers. Using interdigital transducers with a comb gap of 2.5 μm on a piezoelectric ZnO film deposited on the (001) surface of the wafer, we observed the softening of 1.9×10-4in relative amount of the elastic constant Csbelow 2 K down to 23 mK. Taking account of the strong quadrupole-strain interaction, we deduced a small vacancy concentration 3.1×1012cm-3in the surface layer of the wafer within a penetration depth 3.5 μm of the SAW.