IN-SITU TEM OBSERVATIONS OF SILICON CARBIDE FORMATION AND CHARACTERIZATION OF THE SILICON-CARBON INTERFACE

Owing to its large band gap, thermal stability, and high mechanical strength, silicon carbide (SiC) is extensively used in optoelectronics and electronic applications requiring high temperature and wear resistance.^[1-3] Its numerous polytypes offer a broad variation in bandgap which provide many opportunities for device applications. Commercial SiC wafers are limited to a few polytypes such as 4H and 6H-SiC and are constrained by size.^[4] Deeper insights into the fundamental reaction between Si and carbon leading to the nucleation and growth of SiC are important for process development.

In this study we investigated the formation of silicon carbide at silicon-carbon interfaces in carbon coated silicon<110> TEM specimens at temperatures ranging from 700°C-1000°C. Heating was performed in-situ in TEM and ex-situ in a graphite furnace at different temperatures and for various times. The structural and compositional changes of the specimen during ex-situ and in-situ heating experiments was monitored by high resolution and analytical transmission electron microscope (FEI Themis G² 60-300). The silicon-carbon reaction was found to start only above 750°C during in-situ heating experiments, and analysis showed the development of SiC crystalline regions 10 – 100 nm in diameter at 780°C and above. Stacking faults were detected, which are characteristic for the SiC structure.

References:

1. Wesch, W., Nuclear Instruments and Methods in Physics Research Section B 1996, 116 (1-4), 305-321.
2. Casady, J. B.; Johnson, R. W., Solid-State Electronics 1996, 39 (10), 1409-1422.
3. Mehregany, M.; Zorman, C. A., Thin Solid Films 1999, 355, 518-524.
4. Powell, A. R.; Rowland, L. B., Proceedings of the IEEE 2002, 90 (6), 942-955.