Effects of Heating Samples on the Extended Defect Generation during Pulsed Electron Beam Annealing of Silicon
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EFFECTS OF HEATING SAMPLES ON THE EXTENDED DEFECT GENERATION DURING PULSED ELECTRON BEAM ANNEALING OF SILICON
M. PITAVAL, D~partement
M. AMBRI, M. THOLOMIER, D. BARBIER, G. CHEMISKY, A. LAUGIER de Physique des Mat6riaux, Universit6 Claude Bernard - LYON I,
43 Boulevard du 11 Novembre 1918,
69622 VILLEURBANNE C4dex
*Laboratoire de Physique de la Mati&re, Institut National des Sciences Appliqu6es de LYON, 20 Avenue Albert Einstein, 69621 VILLEURBANNE C6dex
ABSTRACT A non destructive SEM observation method has been applied to investigate the extended defects created by pulsed electron beam annealing of arsenic-implanted silicon. The defect study was performed on bevelled 0 samples after irradiation using variable beam fluences for both a 20 C 0 or a 450 C specimen starting temperature. Dislocation generation resulting in subgrain boundaries formation occurs during regrowth of the silicon layer which has been heated up to the melt point or higher. For the rather penetrating electron beam pulse used in this work the subgrain size and their depth extent depend on the beam fluence and the substrate temperature. 0 For 45 0C pre-heated samples, annealing of the arsenic implant is possibl• without any stable extended defect creation using the 1.0 - 1.2 J.cm fluence range. INTRODUCTION The main advantage of Pulsed Electron Beam Annealing (PEBA) over other transient annealing technics lies in the possibility of controlling the deposited energy by means of the electrons spectral distribution [1]. This is particularly interesting in the case of deeply implanted silicon layers for which laser annealing does not succeed in high dopants activation. However this advantage is counterbalanced by extended defect genera-
tion in the regrowth layer as recently reported [2] [3]. By another way, the substrate temperature is likely to play a significant role in the crystal quality of pulsed annealed implanted silicon. So in this work, the substrate temperature is used as a variable parameter to investigate PEBA induced extended defects generation in arsenic-implanted silicon. Structural defects observation has been performed on bevelled samples by means of scanning electron microscopy (SEM) in the channelling imaging (ECI) mode [4]. Defects in the recrystallised layers are mainly low angle grain boundaries. The mean size of the grains and their depth extent have been measured for the various annealing conditions, and results are correlated with thermal computation. I. EXPERIMENTS I.1. PEBA Silicon wafere• (C.Z. grown (001)) were implanted with arsenic ions (140 keV - 10T5 cm ) and annealed by means of a SPIRE 300 pulsed electron beam processor. The pulse durati on was about-PO ns, and the deposited energy was varied from 0.8 J.cmto 1.6 J.cm . In order to modify the recrystallisation kinetics, samples were pre-heated at 450 0 C or kept at room temperature during the annealing process. PEBA thermal effects have been simulated [5] and results are summarized on Table I. Due to the rather penetrating energy deposition profile used in this
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