Electrical Characterization of Deep-Lying Donor Layers Created by Proton Implantation and Subsequent Annealing in N-Type Float Zone and Czochralski Silicon

Abstract

The deep-lying donor layers created by proton implantation and subsequent isochronal annealing were investigated in silicon substrates with oxygen concentration changing from 2x10^16 cm-3 to 1.4x10^18 cm-3. Implantation was performed with 700 keV and 1.8 MeV protons to fluence ranging from 1x10^10 to 1x10^15 cm-2. Results of C-V measurement showed that proton implantation introduces a Gaussian like distribution of shallow hydrogen donors that corresponds to the profile of implanted hydrogen obtained from the secondary ion mass spectroscopy measurement. Subsequent isochronal annealing leads to annealing out of hydrogen donors (~250{degree sign}C) and formation of a series of hydrogen thermal donors (250-350{degree sign}C). In substrates with enhanced concentration of oxygen, the radiation enhanced thermal donors and ordinary thermal donors (>400{degree sign}C) were registered. It was shown that the introduction rate of hydrogen and thermal hydrogen donor layers is enhanced in materials with higher oxygen concentration. However, low oxygen concentration is preferred when better control over spatial distribution of the excess donor profiles is required.

The Impact of Helium Co-Implantation on Hydrogen Induced Donor Profiles in Float Zone Silicon

“…The additional carriers introduced by the helium ions in the co-implanted sample correspond to a significantly greater activation rate of 1.6 % of the implanted helium ions. This latter activation rate is in good agreement with a recently presented value (19). In this publication the peak value of the distribution of the introduced HDs was taken from a sample implanted with 700 keV-protons with a fluence of 1×10 13 cm -2 without successive annealing.…”

“…Among its numerous reported characteristics in silicon, hydrogen is known to passivate electrically active intrinsic point defects by saturating all open bonds of the defect, e. g. V-H 4 . Possibly, analogous to the observations in samples overexposed to a hydrogen plasma (7-10), the increasing local hydrogen concentration near R p-H causes a deviation from the reported linear scaling at fluences up to some 10 13 cm -2 (19) for donor species created after annealing at ∼470 °C.…”

Activation and Dissociation of Proton-Induced Donor Profiles in Silicon

“…The principal dependence of the charge-carrier concentration on the annealing temperature are known from recent publications. 46,47 However, these studies disregard the impact of the annealing time on the thermal budget. Only the assignment of effective dissociation barriers to the individual donor species allows for an accurate description of the annealing-out of the proton-induced HDs.…”

Depth-Resolved Imaging of Radiation-Induced Doping Changes in Silicon

“…It was absent when annealed in vacuum and in irradiated standard FZ silicon, confirming their dependence on the oxygen concentration. In another study by the same authors 19 donor creation in FZ and CZ silicon by 0.7 and 1.8 MeV proton irradiation and annealing was compared. In substrates with a high concentration of oxygen, both radiation enhanced thermal donors and ordinary thermal donors were observed above 400 • C. In standard FZ the donor peak at the end-of-range slightly broadened after annealing at 300 • C, attributed to diffusion of the implanted hydrogen and its interaction with irradiation defects.…”