Activation and carrier mobility in high fluence b implanted

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The dopant activation and carrier mobility as function of depth has been determined by differential Hall and spreading resistance measurements. It was also found that molybdenum sputtered in the source are chamber and co-implanted with BF2 segregates together with F. B diffusion is unaffected by the presence of these precipitates.

For the 10 keV implanted wafers instead, no segregation of fluorine is found. Hall measurement analysis shows that the fluorine trapped in the layers and the presence of precipitates do not affect the carrier mobility in the high temperature annealed wafers. Proceedings Cat.

Article :. DOI: Need Help?Julien L. Heasman and Russell M. E-mail: j. We demonstrate that accurate RBS is a definitive method to determine quantity of material.

It is therefore useful for certifying high quality reference standards, and is also extensible to other kinds of samples such as thin self-supporting films of pure elements. Ion implantation is an intrinsically controllable process, involving ion beams of well-defined energies: the physics of the stopping energy loss processes is now very well understood, and determining the total fluence simply involves counting the charged particles — measuring electrical current can be done at extremely high accuracy.

However, as Gries points out, the charge measurement depends on efficient Faraday cups: in fact, as he acknowledges, the electronic environment during ion implantation is complex; secondary currents can be much larger than the primary current to be measured, and large tertiary and higher order currents may also exist including neutral and positive currents. It is by no means trivial to get and keep effective Faraday cup charge measurement, especially considering the intermittent current the cup sees with a scanned beam which intermittency can give large errors if not handled correctly 10 and considering that the beam usually does not fall fully into the cup as it scans over it: energetic ion beams striking cup aperture edges produce copious secondary particles, both electrons and ions especially in the forward direction which have to be very efficiently suppressed for quantitative implantation.

Reliable quality assurance QA of the fluence control system depends on subsequent qualification of implanted material, which is equivalent to verifying the correct behaviour of the charge collection system.

For dopant implants this is conveniently done by 4-point-probe 4pp sheet resistivity measurements, but these are indirect and also depend on a well-controlled anneal to completely activate the implanted atoms. Consequently, resistivity is usually treated as a very precise relative measurement. Here we use RBS as a primary direct method 17 traceable to the Sb-implant certified reference materials Sb-CRM 18,19 through an intrinsic material property, the silicon stopping power factor, whose value was first claimed in in the course of an IAEA-sponsored intercomparison exercise see Fig.

In the present work we fully establish the RBS uncertainty budget incorporating further work by Colaux et al. High accuracy RBS results are complemented by 4-point-probe 4pp resistivity measurements both for relative fluence measurements and for assessment of the implant uniformity. QA measurements were also extended to other implants various ion species, energies and fluences to more fully validate the quantitation capabilities of our implanter.

In detail, considering Fig. Eqn 1 and 2 are simplified without loss of generality, and were discussed in all their complexity previously. Quantitative implantation is effected by the special design of both: Faraday cups able to efficiently suppress secondary and higher order currents, and also of the four current integrators using three different designs able to accurately integrate highly intermittent beam currents.

By comparing the outputs of the four Faraday cups, under-scanning and other errors can be detected and reliable indicated fluences delivered. Well-controlled implants will have the four FCs agreeing often to better than 0. We therefore expect our quantitative implantation to give fluences closer than 1.

Table 2 sketches the uncertainty budget: a full discussion is outside the scope of this paper; however, this work makes clear that the random measurement error will be dominated by the trueness of the fluence measurement of the FCs, that is, their efficiency in suppressing secondary and other currents.

The advantages of arsenic as a test implant are: a RBS measurements are sensitive, having only the pileup as background; b As is a good silicon dopant with very high solubility so that parallel resistivity measurements can be made on the same wafer; c this heavy-ion implantation is a demanding test of the Faraday cup performance since it generates copious secondary and higher order currents in the target chamber; d arsenic implants at this fluence fully amorphises the Si crystal to about nm depth provided the implant temperature does not much exceed room temperature self-annealing is discussed in detail by Murakoshi et al.

The sensitivity of the 4pp to fluence is much better at 0.To browse Academia. Skip to main content.

activation and carrier mobility in high fluence b implanted

Log In Sign Up. Download Free PDF. Activation and carrier mobility in high fluence B implanted germanium. Salvo Mirabella. Impellizzeri, A. Piro, E. Bruno, and M. These results allow reliable evaluation for Ge application in future microelectronic devices. In addition, an accurate carried out under not-well defined conditions and restricted room-temperature concentration-dependent hole mobility to low-medium doping regimes.

Nuclear reac- Ge. Further 1 h an- B tion highly difficult. Different rH val- effect using a magnetic field of 0.

A In Fig. Still, increasing the implant flu- ence, the active B dose increases with an underlinear slope, due to the larger dopant amount below Bmax. The evident slope change in the NH plot is related to the maximum active dopant level we wish to determine. Once the Hall factor is fixed and given the implanted profile,15 the measured Hall dose versus implant B fluence can be simulated at different Bmax values, considering all the dopant distribution below Bmax as fully ionized.

The results of such an exercise are reported in Fig. This Bmax value for Si is in agreement with literature data,19 while the measured Bmax in Ge is higher than what previously reported. Moreover, a further, not-trivial difference is that we can ne- glect any surface-related effect because of the nm deep R p, while for low-energy B implants surface oxidation or proximity can induce fouling up phenomena such as en- hanced dopant precipitation, or outdiffusion, lowering the so measured dopant activation.

The NH plot reveals a linear trend up to a certain B The inactive B fraction does not show any thermal variation fluence, above which an underlinear slope is reported. Although rH is generally concentration dependent, it is These values are reported in Fig. As expected, drift mobility for holes agreement with literature data in similar concentration in Ge is well higher than in Si.

Still, in the investigated N regimes. For tals properties should account for the different rH values.Print Send Add Share.

Notes Abstract: The physical scaling associated with integrated circuits is exhausting the properties of Si and requires that advanced materials be used for future device generations.

activation and carrier mobility in high fluence b implanted

Ge is widely regarded as a possible replacement for Si due to its enhanced mobility and reduced contact resistance. However, the information regarding technologically relevant ultra-shallow dopant implants into Ge and their associated activation behavior is currently sparse and must be fully understood prior to implementation into future devices. The activation behavior is further explained through the largely immobile B atoms which have a distinctly low probability of recombining with a vacant site due to the overwhelmingly large population of interstitials created during implantation as simulated by SRIM.

The excess interstitial population increases competition for B recombination on a vacant lattice site and thereby reduces B activation. The observed activation behavior in this work is a strong departure from what has been observed previously for B in Si. General Note: Includes vita.

Bibliography: Includes bibliographical references. Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication.

The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. Thesis: Thesis Ph. Local: Adviser: Jones, Kevin S. Local: Co-adviser: Law, Mark E.

activation and carrier mobility in high fluence b implanted

Statement of Responsibility: by Bradley R Yates. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes.

Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. While I am earning the degree from the University of Florida, it seems like the majority of this work was completed at other institutions. I have travelled and sent samples around the world, but this work would not have been completed if it w as not for those closest giving me their support.

To begin, I w ould like to thank my mother, family and friends for always being there for me during my academic career The support received was probably not outwardly recognized, but its effect was impo rtant nonetheless. I would also like to acknowledge all of the help that my advisor, Dr. Kevin Jones, has given me along the way. Foolishly, I had turned down his initial offer to join his group just to plead with him one year later for admittance.

For this, I will always be grateful. I also appreciate all of the help given to me by Dr. Mark Law, Dr. Toshi Nishida, Dr. Gerald Bourne, Dr. Luisa Amelia Dempere and Dr. Rajiv Singh for sitting on my supervisory committee I also need to thank Dr. John Talbo tt for his support of my academic endeavors ; this will never be forgotten and I will be sure to pay it forward. I would also like to thank all of the members of the group that have helped me along the way.

Everyone from Pat Whiting with his seemingly nev er ending supply of academic memes to Nick Rudawski with his imitations of th ose that shall go written with Nick in mind. All of my interactions here at the University of F lorida have been positive and have been instrumental in achieving this goal.

PAGE 5 5 I would also like to thank the countless collaborators that have helped me with this project. I would also like to acknowledge Lucia Romano of the University of Catania and Barney Doy le of Sandia Nationa l Laboratories for their assistance with ion beam analysis. The project would not have been possible without the funding p rovided by Intel. A 35 keV implant corresponds to an R P of 90 nm The presence of the native oxide surrounding th e pit is evident.These quantities were correlated with boron and fluorine chemical depth profiles obtained with secondary ion mass spectrometry SIMSand with the lattice defects revealed by transmission electron microscopy TEM.

In the high fluence implanted samples, the solid phase epitaxial regrowth of the amorphous layer induces a severe fluorine redistribution which causes the formation of a defective band at the sample surface containing microtwins and small precipitates; a decrease in both the activated dopant concentration and carrier mobility was found in this region. Download to read the full article text.

Liu and W. Google Scholar. Lunnon, J. Chen and J. Baker, J. Cohen, J. Norton, E. Kock and G. Weisel, J. Wilson, J.

activation and carrier mobility in high fluence b implanted

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Matsumura, Y. Nakagome and S. Furukava, Appl. Prussin, D.A method for ion-implanting a dopant species in semiconductors includes the steps of implanting a dopant species in a semiconductor material at a predetermined rate, the predetermined rate being based on a rate corresponding to a maximum in a characteristic graph of percent activation as a function of dopant species implantation rate; and annealing the dopant implanted semiconductor.

This invention relates to the field of electrical activation of ion-implanted semiconductors. In particular, the invention relates to ion-implanted silicon in GaAs.

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The ion-implantation of semiconductors, and in particular the ion-implantation of silicon into GaAs, is an important doping technology for device fabrication. Particle accelerators accelerate silicon ions to impinge on and be implanted into GaAs.

Implantation is followed by an annealing procedure which removes radiation induced damage and thermally transports dopants into lattice positions where they become electrically active. For low fluences from nil to. At higher fluences on the order of The study of electrical activation of implanted dopants in GaAs as a function of implanted species, fluence and post-implant processing annealing has been an active research area in recent years.

The ion-implantation process induces damage in the crystalline structure of the semiconductor. The annealing process reduces or ameliorates a portion of the induced damage. The study of implantation induced damage and its anneal characteristics has been ongoing for an even longer time than the study of electrical activation.

Few of these studies report the dose rate with which the fluence was administered and there have been no studies reporting the impact of various dose rates on the electrical activation of the implanted species.

Japanese Patent No. Ozawa discloses obtaining a peak carrier concentration of 7. Ozawa does not disclose activation percentages or their dependency on implantation dose rates. Ozawa does not disclose the dependence of electrical activation on implantation dose rates. The Kwok et al. Tomura does not disclose the dependence of electrical activation on implantation dose rates. Jackson et al. It is an object of the present invention to provide a method by which electrical activation of dopants in semiconductor materials can be enhanced.

In particular, the percentage activation of dopants when applied in high concentrations in semiconductors are enhanced by the methods described herein. It is another object of the present invention to overcome deficiencies in the prior art by a method which enables high percentage activations of dopant to be achieved without requiring additional processing steps. It is yet another object of the present invention to allow high percentage activation of dopants to be achieved in an inexpensive manner.

It is another object of the present invention to provide a method by Which electrical activation of dopants in semiconductor materials can be enhanced using standard processing techniques.

To achieve these and other objects, the inventors herein have discovered that the percentage of electrical activation of high concentrations of dopants in semiconductors is enhanced by controlling the dose rates of the ion-implantation of the dopants. In particular, silicon and sulphur ions implanted into GaAs at controlled implantation dose rates which accumulate to high dopant concentrations exhibit high electrical activation percentages when annealed.

The method described herein comprises implanting a dopant species in a semiconductor material at a predetermined rate, said predetermined rate being based on a rate determined so that a maximum in a characteristic graph of percentage activation as a function of dopant species implantation rate is the predetermined rate. For instance, The enhancement can be by as much as a factor of 3 over the activation obtained using lower and higher dose rates.

It will be appreciated that different dopant species, implantation parameters e. Nevertheless, for each combination of dopant species in semiconductor material type, an optimal dose rate will exist. The optimal dose rate can be determined from a characteristic experimentally determined graph of activation verses ion dose rate. The invention will be described in detail in the following description of the preferred embodiments with reference to the following figures wherein:.

Described herein is a study of electrical activation of silicon implanted at a fluence of The study shows that electrical activation depends strongly on the dose rate of the implantation.

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