Improved Annealing Process for 6H-SiC p⁺-n Junction Creation by Al Implantation

Mihai Lazar (1, 2) , Laurent Ottaviani (1, 2) , Marie-Laure Locatelli (1, 2) , Dominique Planson (1, 2, 3) , Bruno Canut (4) , Jean-Pierre Chante (1, 2)

1 CEGELY - Centre de génie électrique de Lyon
2 INSA Lyon - Institut National des Sciences Appliquées de Lyon
3 EE - Ampère, Département Energie Electrique
4 DPM - Département de Physique des Matériaux

Five-fold Al implantations at both room temperature and 300°C ranging from 25 keV to 300 keV and a total fluence of 1.75x10 15 cm-2 , have been performed in 6H-SiC epilayers to create p +-n junctions. The samples have been annealed at 1700°C during 30 mn in an inductively heated furnace especially configured. Surface effects, recrystallization, dopant distribution and electrical activation are investigated by XPS, RBS, SIMS and sheet resistance measurements. For both RT and 300°C-implanted samples, good recrystallization and surface stoichiometry are found as well as no dopant loosing and an interesting electrical activation (46% and 99%, respectively). Introduction p +-n junctions in SiC power devices must be realized by ion implantation due to very low diffusion coefficients of dopants in silicon carbide. SiC high density and its structural crystallinity involve a delicate post-implantation annealing. The implantation temperature, annealing environment, time and temperature of annealing and the heating rate are the essential parameters to reorder the crystal damage induced by ion implantation and to activate the dopants by migrating in SiC atomic sites. Initially, after ion implantation, almost all Al dopants are distributed in interstitial sites, where they are not electrically active. We utilized a JIPELEC TM rf induction furnace. This technique of annealing has significant advantages such as the very high rising slope in temperature and the very localized zone of heating (the susceptor). But this one implies high temperature variations, vertically in the enclosure and laterally on the surface of the SiC wafers. These temperature gradients may cause an etching of, or a layer deposition on the SiC surface. Moreover, Si is known to volatilize towards 1400°C at one atmosphere pressure, and in lack of a Si supersaturating vapor the carbonization of the surface is inevitable. This paper presents the results of an optimized thermal rf annealing, which avoids these problems.

Mots clés: Ion Implantation; Annealing; Surface Stoichiometry; RBS/Channeling; SIMS; Electrical Activation

Domaines: Energie électrique

Mihai Lazar, Laurent Ottaviani, Marie-Laure Locatelli, Dominique Planson, Bruno Canut, et al.. Improved Annealing Process for 6H-SiC p⁺-n Junction Creation by Al Implantation. Materials Science Forum, 2000, 338-342, pp.921-924. ⟨10.4028/www.scientific.net/MSF.338-342.921⟩. ⟨hal-02275720⟩