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M5.49.1

DLTS studies of defects produced in n-type silicon by hydrogen implantation at low temperature Takahide Sugiyama1, Masayasu Ishiko1, Shigeki Kanazawa2 and Yutaka Tokuda2 1 Toyota Central R&D Labs., Inc., Nagakute, Aichi 480-1192, Japan 2 Department of Electronics, Aichi Institute of Technology, Toyota 470-0392, Japan

ABSTRACT Metastable defects are discovered in hydrogen-implanted n-type silicon. Hydrogen implantation was performed with the energy of 80 keV to a dose of 2x1010 cm-2 at 109 K. After implantation, the sample temperature was raised to room temperature. DLTS measurements were carried out in the temperature range 80-290 K for fabricated diodes. When the sample is reverse-biased at 10V for 10 min at room temperature and then is cooled down to 80 K, three new peaks labeled EM1, EM2 and EM3 appear around 150, 190 and 240 K, respectively. The introduction of metastable defects is found to be characteristic of low temperature implantation. We have evaluated properties of EM1 in detail. EM1 with thermal emission activation energy of 0.29 eV has a peak in concentration around the depth of 0.64μm, which corresponds to the projected range of 80 keV hydrogen. EM1 is regenerated with the reverse bias applied around 270 K and is removed with the zero bias around 220 K.

INTRODUCTION It has been well recognized from DLTS [1] measurements that two hydrogen-related defects are observed in n-type silicon implanted at room temperature by hydrogen ions in addition to three vacancy-related defects which are vacancy-oxygen pair (VO), divacancy (VV) and vacancy-phosphorus pair (VP) [2-5]. One hydrogen-related defect (Ec – 0.32 eV) has been identified as the complex of VO with hydrogen [4]. Some of irradiation-induced defects display metastable or multistable behavior. Carbon-related defects such as interstitial carbon-substitutional carbon pair and interstitial carbon-phosphorus pair are well-known metastable ones and have been extensively investigated by DLTS so far [6-8]. Recently, it has been reported that a metastable defect at Ev + 0.43 eV is induced in epitaxially grown p-type silicon by alpha particle irradiation [9]. In spite of a growing number of discoveries of metastable defects, to our knowledge, there seems to be no reports on the observation of metastable defects which are characteristic of hydrogen implantation. Since hydrogen is the lightest element, it seems natural to expect the metastable defects which are hydrogen-related. Indeed, hydrogen-related metastable defects have been discovered in GaAs [10,11]. Recently, Nielsen and Holm have reported the production of a metastable defect after ambient gas-flow annealing at ~900°C and subsequent cleaning procedure which causes hydrogen injection [12]. They have suggested that the generated defect by annealing is activated by hydrogen.

M5.49.2

In the present paper, we report the first observation of metastable defects in n-type silicon implanted by hydrogen ions. It is shown that the creation of hydrogen-related metastable defects is realized by hydrog