Redistribution of manganese after annealing of GaAs implanted with Si+ and Se+

The stress introduced by the difference in thermal expansion coefficients between an encapsulant and a substrate was found to affect the redistribution of implanted impurities during annealing. Compressive stress introduced by an SigN4 film on GaAs enhanced the diffusion of implanted Si, Se, and S. Diffusion constants of Si and Se increased exponentially with the increase in the film thickness in a thickness region less than 0.1 ~m. The diffusion mechanism was discussed and it was concluded that the change in the jump frequency of diffusing atoms was dominant in determining the effect of stress in the damaged implantation layer. Excess of carriers was also observed in Se-and S-implanted samples, while deficit in carriers was observed in Si-implanted samples when the samples were subsequently annealed with an Si3N4 film. ~mall logic swing is essential for achieving a GaAs logic integrated circuit, particularly in ennancementmode logic circuits, where logic swing in Schottky barrier FETes should be 0.7V at most and that in junction FET's 1.2V to avoid appreciable gate current. Channel layers of both FET's are usually formed by ion implantation directly into a semi-insulating ~ubstrate. Variation of the carrier concentration profile in the ion-implanted channel layer over the whole wafer is a most crucial problem for uniformity and reproducibility of the devices. Precisely controlled ion-implanted layers are required to achieve GaAs integrated circuits.ion implantation technology is advantageous, because it can, in principle, control the profile for the channel layer only by changing the implantation energy and ion .dose. The profile is predicted by the LSS range statistics (1). A damaged layer by ion implantation, however, has to be annealed at high temperature in order to remove radiation damage and to activate implanted impurities as donors or acceptors. Implanted impurities are redistributed by diffusion during postimplantation annealing at high temperature. The factors affecting the redistribution were discussed previously by Kasahara and Watanabe (2) and Yoder (3). Thermal stress during post-implantation annealing was pointed out to be one of the factors, and the example was shown in the case of Zn ion implantation into GaAs (2). The effect of the thermal stress on the redistribution of Cr in Cr-doped semi-insulating substrates was also reported (4, 5). However, it is not clear how the stress influenced the redistribution of implanted impurities in GaAs.In this paper, the effect of the external stress on the redistribution of implanted Si, Se, and S in GaAs is investigated by using a wafer with thermal stress introduced by the .difference in the thermal expansion coefficient between an encapsulant and GaAs. Following the descriptions of the experimental conditions and the results, we discuss variations in the diffusion constants of implanted Si and Se under a wide range of external stress conditions. Variations in the doping efficiency of the implanted impurities are also described briefly as a function of the...

Section: Discussionmentioning

confidence: 99%

The Effect of Stress on the Redistribution of Implanted Impurities in GaAs

Kasahara¹,

Kato²,

Arai³

et al. 1983

“…This illustrated the need to consider the surface condition of the GaAs with respect to surface gettering of Mn (and other fast diffusing species). "Silox" SiO~ caps, which contain excess O and H~O, getter Mn even when the anneals take place in the CAT atmosphere (9).…”

Section: Discussionmentioning

confidence: 99%

Substrate Impurity Migration during Rapid Thermal Annealing of Si Implanted GaAs

Kanber

Whelan

1987

One of the potential advantages of rapid thermal annealing (RTA) compared to conventional furnace annealing is reduced implant dopant and background impurity diffusion. In this paper, the migration of Cr and Mn during annealing of Cr-doped semi-insulating GaAs implanted with 100 keV Si + ions at a dose of 7 • 10 '~ cm -~ was measured using SIMS. We investigated uncapped RTA at 860 ~ and 930~ for times between 1 and 60s and compared them to capless 30 rain furnace anneals. During RTA, Cr migration was severe and showed a strong time-temperature dependence. Mn migration was undetectable for RTA anneals less than 60s, but dominated the 30 rain furnace anneals.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.120.3 Downloaded on 2015-05-28 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.120.3 Downloaded on 2015-05-28 to IP

“…To obtain Rp and (rrp as a function of implantation energy, E, an experimental database is generated from this study and also from earlier literature (19)(20)(21)(22)(23)(24). The results are shown in Fig.…”

Section: Activation Efficiency--the Activation Efficiency In Thismentioning

confidence: 99%

A Process Simulation Model for Silicon Ion Implantation in Undoped, LEC‐Grown GaAs

Bindal

Wang

Chang

et al. 1989

The activation efficiency of implanted Si in LEC grown normalGaAs has been investigated experimentally. Atomic and carrier distributions of the implant have been obtained using SIMS, conventional, and step‐etch C‐V techniques, respectively. Based on these experimental observations, Si activation efficiency is found to be a strong function of the implantation fluence and annealing temperature, and a weak function of the implantation energy and annealing time. An activation efficiency model is also constructed as the result of these experimental evaluations. For simplicity the model ignores all the weak processing parameters in the computation of activation efficiency. A model reproducing the atomic concentration profile for a given implant has also been developed to use in the activation efficiency model.