Pure-boron chemical-vapor-deposited layers: A new material for silicon device processing

This paper places focus on the special properties of pure boron chemical-vapor deposition (CVD) thin-film layers that, in several device applications, have recently been shown to augment the potentials of silicon device integration. Besides forming a reliable an efficient dopant source for both ultrashallow and deep p⁺n junctions, the deposited amorphous boron (α-B) layer itself, even for sub-nm thicknesses, is instrumental in suppressing minority electron injection from the n-region into the p⁺ contact. Therefore, even for nm-shallow junctions where the current levels mainly will approach high Schottky-like values, the diodes exhibit saturation current levels that can become as low as that of conventional deep junctions. Moreover, the α-B layer has chemical etch properties that make it particularly suitable for integration as the front-entrance window in photodiodes for detecting nm-low-penetration-depth radiation and charged particles.