Dual ion implantation technique for formation of shallow p+/n junctions in silicon

Abstract

To produce thin p+ layers in n-Si substrates, low-energy B+ ions have been implanted into amorphous layers formed by the prior implantation of Si+ ions. Thermal annealing results in recrystallization of the amorphous material by solid-phase epitaxy. After annealing, the B depth profile determined by secondary ion mass spectrometry is close to the calculated profile, transmission electron microscopy shows that the implanted layer is of good crystal quality, and sheet-resistivity measurements show that electrical activation is complete. Diodes with p+/n junctions ∼0.25 μm deep produced by the dual implantation technique show excellent I-V characteristics, with reverse leakage current densities ∼5 and 16 nA/cm2 at −1 and −5 V, respectively. P-channel metal-oxide-semiconductor field-effect transistors fabricated using the dual implantation technique exhibit superior electrical characteristics compared to similar devices fabricated using the conventional single B implant process.

Furnace and Rapid Thermal Annealing of P+/n Junctions in BF 2 + ‐ Implanted Silicon

“…A similar defect structure is observed if the boron fluoride implant is omitted, indicating that the damage is characteristic of the silicon implant. Almost complete elimination of implant damage has been reported for multiple silicon implants followed by a boron implant and furnace annealing (6). It has been shown here that this can be achieved by furnace annealing of dual silicon and boron fluoride implants.…”

Defective Solid-Phase Epitaxial Growth of Si

“…As the growth interface reaches the implanted dopant atoms, the dopants incorporate substitutionally due to the epitaxial nature of the process, and become electrically active. In fact, active dopant concentrations in excess of equilibrium solubility can be achieved via SPEG (Bousetta et al, 1991;Ozturk et al, 1988;Tsaur and Anderson, 1983;Vonborany and Kogler, 1993). In contrast, if activation of implanted dopant atoms is attempted in crystalline material, substitutional incorporation of the dopant can only occur if vacancies are present, and the dopants and vacancies have enough mobility to combine during annealing.…”

Challenges in advanced semiconductor technology for high-performance and supercomputer applications

“…Problems exist in controlling both the depth of the initial ion implanted profile and paths are absent, channeling is greatly reduced. Silicon [123][124][125], germanium [126][127], and even tin [128][129] implants have been used for this purpose. By combining preamorphization with low-energy ion implantation, junction depths as shallow as 0.1 ~m can be obtained, as seen in Figure 10 [130].…”