Theoretical Analysis of Homogeneity and Surface Degradation during Pulsed Electron Beam Annealing of GaAs and InP
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THEORETICAL ANALYSIS OF HOMOGENEITY AND SURFACE DEGRADATION DURING PULSED ELECTRON BEAM ANNEALING OF GaAs AND InP A. LAUGIER, D. BARBIER, G. CHEMISKY Laboratoire de Physique de la Mati~re (LA 358) Institut National des Sciences Appliqu6es de Lyon 20, Avenue Albert Einstein 69621 VILLEURBANNE CEDEX (France)
ABSTRACT PEBA induced thermal effects in GaAs and InP have been simulated. MonteCarlo calculation has been used to determine universal electron energy loss functions in the 5-50 keV energy range for these materials. Similar electron depth-dose profiles of a polykinetic electron beam pulse is deduced in both GaAs and lnP. A simple adiabatic approach is sufficient to establish relationship between melting depths and fluences. Thermal effects homogeneity and surface degradation are discussed for both crystalline and amorphous materials using variable electron energy deposition profiles. Correlation is made between experimentally measured degradation thresholds and calculated fluence windows within which melting effects are expected. INTRODUCTION The ease of generation, control and energy transfer to solids associated with electron beams has led to their incorporation in many systems for transient thermal processing of semiconductor materials. Pulsed electron beam processors based on a field emission diode deliver beams of large diameter with some inhomogeneities due to the anode (grid screening) and cathode (plasma instabilities). These inhomogeneities have no significant effects for annealing of Si but can be critical for semiconductor-compounds for wich surface instabilities can occur. This work is devoted to GaAs and InP processed with pulses of 50 ns in duration. Pulsed laser and e-beam have been used to anneal implanted damage in group 111-12/serdconductors but have met with limited success. Low dose n-type implants (10 cm ) are needed for the channel of GaAs FETS and high doses are needed for making low noise, ohmic contacts. The important1 electrical characteristics obtained from pulse-annealed GaAs are summarized below ( ) : i) high doses of both n- and p-type dopants can be activated, even well above doping concentrations which can be achieved by conventional furnace annealing, ii) low dose of n-type dopants are not activated, iii) mobilities of n-types layers are poor, iV) activated layers have poor thermal stability. In addition for InP, Rutherford backscattering has shown important phosphorous losses at the surface [33. This paper presents a theoretical analysis of homogeneity and surface degradation during oulsed electron beam annealing of implanted GaAs and InP. This analysis is facilitated because e-beam allows a precise determination of the time-dependent energy distribution versus time during the pulse and versus depth in the material.
Mat. Res. Soc. Symp. Proc. Vol. 23 (1984)(
Elsevier Science Publishing Co., Inc.
700
MONTE-CARLO CALCULATION OF THE ENERGY DISTRIBUTION Electron beam processing systems rely on the transfer of energy from the beam to the solid. When the beam strikes a material a
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