Improvement in MOS VLSI Device Characteristics Built on Epitaxial Silicon

Abstract

Two advantages (freedom from ground loops and enhanced performance of diffused guard rings) of P+/P− epitaxial versus homogeneous crystal substrates in 64K DRAM are presented. Reduced refresh time and pattern sensitivities of the early TMS 4164, built on homogeneous substrate, are chronicled. To better understand the significant improvements with epitaxy, models are investigated for substrate capacitive/drift current coupling and for guard rings. Substrate-coupling modeling primarily used an instantaneous view of potential distributions via solution of Laplace's equation, followed by time-domain analysis. A comparison is made with a discrete resistor mesh. Guard ring study was empirical. Sets of biased diffused annular rings, surrounding an n+ dot used for minority carrier injection, were fabricated on both types of substrate. Results of the theoretical and experimental studies are compared with device performance.

On the Mechanism of Oxygen Content Reduction by Antimony Doping of Czochralski Silicon Melts

“…The following two reactions can occur at the melt surface Si(1) + [0] ~ SiO(g) [1] 4[Sb] + 6[0] ~-Sb406(g) [2] To clarify which evaporation process is dominant, we need to analyze the following reaction…”

“…Antimony-doped Czochralski (CZ) silicon has attracted an increased interest in advanced complimentary metal oxide semiconductor (CMOS) fabrication in recent years (1). It has been established that heavily antimony-doped CZ silicon contains less oxygen than lightly doped crystals.…”