Line-Source E-Beam Crystallization of Silicon-On-Insulator Films
- PDF / 2,603,412 Bytes
- 5 Pages / 417.6 x 639 pts Page_size
- 70 Downloads / 201 Views
LINE-SOURCE E-BEAM CRYSTALLIZATION OF SILICON-ON-INSULATOR FILMS*
J. A. Knapp and S. 87185, USA
T.
Picraux,
Sandia National Laboratories,
Albuquerque,
NM,
ABSTRACT Silicon-on-insulator films have been formed using a 20 mm by 1 mm line-source electron beam, with sample sweep speeds of 2 100-500 cm/sec and peak beam power densities up to 75 kW/cm . Films were formed over 1 and 2 ým thick Si0 2 isolating layers on 4" diameter Si wafers, with stripe openings of 5 to 100 •m width for seeding the crystallization from the substrate. Films consisted of Si layers from 0.4 to 1.0 pm thickness, with a capping layer of 2 Pm Si0 2 . By sweeping the beam parallel to the long axis of the seed openings, smooth, oriented films were obtained, with low-angle grain boundaries confined to midway between seed openings. Best results were obtained for 4 50 im spacing between seed openings.
INTRODUCTION A number of approaches to the formation of silicon-on-insulator (SOI) structures are being investigated [1]. Our studies have centered on the use of a high-power line-source e-beam to melt the isolated Si layer at relatively fast sweep speeds [2]. The results reported here concern the use of seed openings in the isolation layer to control the orientation and quality of the recrystallized Si layers. Control or elimination of grain boundaries in melt-recrystallized SOI is the goal of several studies using various techniques. One method [3] is to control the orientation of growth over an isolated island or area by using seeding from the substrate. Another method is to control the shape of the molten zone, and hence, the location of low-angle grain boundaries by using patterned anti-reflection coatings for optical excitation [4,5]. We have used seed openings to the Si substrate for both purposes in e-beam melting and recrystallization. In this way, both the regrowth orientation, the heat flow and subsequent low-angle grain boundary locations are determined by the pattern of the seed openings. EXPERIMENTAL The electron beam system has been described earlier [2]. The beamshaping electrodes have since been reconfigured to give a more uniform and reproducible beam of 1.1 mm full-width at half-maximum in the narrow dimension and 2-3 cm long. For the SOI studies, beam energies of 30-38 keV 2 were used, with peak power densities of up to 75 kW/cm . Samples were 0 ohmically heated in situ to 400-500 C and swept under the beam at speeds of 100-500 cm/sec. The sample fabrication began 4" Si wafers. Seed openings pattern of stripes 350 pm long by apart. The openings were aligned
with a 1 or 2 Pm Si0 2 isolation layer on were etched through to the substrate in a 5-100 pm wide and spaced from 5 to 200 pm with the axis. A polycrystalline
*This work performed at Sandia National Laboratories supported by the US Department of Energy under contract number DE-AC04-76DP00789. Mat. Res. Soc.Symp. Proc. Vol. 23 (1984)(
Elsevier Science Publishing Co., Inc.
534
silicon (poly Si) layer of 0.4 - 1.0 pm thickness was then deposited, followed by a capping l
Data Loading...
