LATERAL INHOMOGENEOUS BORON SEGREGATION DURING SILICON THIN-FILM GROWTH WITH MOLECULAR-BEAM EPITAXY

Boron segregation from submonolayer (less than 0.1 monolayer) interfac ial boron deposition during thin film silicon growth with molecular be am epitaxy (MBE) in the temperature range 450 to 800-degrees-C has bee n investigated by secondary ion mass spectrometry (SIMS) with high dep th resolution and lateral resolution of a few micrometer. Beginning at 600-degrees-C, segregation-induced ''kinks'' occur in the boron profi les developing into shoulders for higher growth temperatures and/or lo wer deposition rates. At temperatures above 700-degrees-C at the shoul der a concentration of (1-2)x10(19) cm3 Was found. Interfacial carbon showing significantly less segregation has been used as a marker. Late rally resolved SIMS measurements indicate inhomogeneous boron distribu tion, mainly due to residual substrate contamination. These inhomogene ities strongly influence the segregation behaviour, as shown by SIMS c ross-section analysis, and can result in local boron penetration throu gh multilayer structures, demonstrating the importance of appropriate cleaning procedures for residual boron substrate contamination.