Planar channeling effects in a batch process ion implanter

Liebert, R.B.; Downey, Daniel F.; Basra, Vijay K.

doi:10.1016/0168-583x(87)90863-9

Cited by 6 publications

(2 citation statements)

References 11 publications

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“…The skewness is a measure of the tilting of the profile, and the kurtosis relates to the shape of the top of the profile (i.e., sharp or rounded peak). The equations in [3] can be solved for the four constants of the Pearson distribution function…”

Section: Description Of New Modeling Approachmentioning

confidence: 99%

“…This has been a particularly difficult task for the case of boron due to the strong channeling tendency of this light atom in silicon. Indeed, the degree of channeling has been shown to depend considerably on both the tilt and rotation (or twist) angles during ion implantation, even for those ranges of angles for which channeling is generally considered to be minimal (1)(2)(3).…”

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An Improved Approach to Accurately Model Shallow B and BF 2 Implants in Silicon

Tasch

Shin

Park

et al. 1989

J. Electrochem. Soc.

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In this paper, an improved modeling approach is described for simulating as-implanted boron impurity profiles for B + and BF2 ~ implants into single*crystal silicon. This method uses the sum of two Pearson distribution functions to account for the nonchanneling and channeling components of the implant distribution. The ratio of the two Pearson functions varies with dose, which accounts for the change in the degree of channeling with dose. This modeling approach has been compared with experimentally measured SIMS profiles for a wide range of energies and doses for shallow B § and BF2 § implants. The excellent agreement indicates that this method offers a large improvement in simulation capability for B § and BF2 § implants. In addition, this method should be applicable to accurately model other impurities which have channeling tendencies.In the development of submicron-integrated circuit technologies, much attention is currently focused on the achievement of reproducible and uniform (over the wafer) shallow, compact impurity profiles for both shallow junctions and the adjustment of various threshold voltages. Also, the entire impurity profile is of interest, in particular for the shallow source-drain junctions in CMOS. This is because of the need to simultaneously have low sheet resist~ ance, very high surface concentration for low contact resistance, a shallow junction, and profile control in order to minimize high electric fields which can cause hot carrier reliability problems. This has been a particularly difficult task for the case of boron due to the strong channeling tendency of this light atom in silicon. Indeed, the degree of channeling has been shown to depend considerably on both the tilt and rotation (or twist) angles during ion implantation, even for those ranges of angles for which channeling is generally considered to be minimal (1-3).Extensive use of process modeling is mandatory for timely, efficient technology development and in order to understand the process control issues in manufacturing. Thus it is necessary to be able to accurately predict impurity profiles beginning with the as-implanted distribution and continuing with the evolution (diffusion) of the profile in subsequent thermal treatments. In addition, the models used to describe the profile evolution in furnace and rapid thermal processing can only be valid over a wide range of conditions if they begin with the correct initial as-implanted impurity distribution. Otherwise, erroneous assumptions must be made in the model in order to relate its predicted diffused profile with the initial implanted profile. This is especially the case when rapid thermal annealing is used.Historically it has been difficult to accurately simulate as-implanted boron distributions for both B+ and BF2 + implants. This is mainly due to the ease with which boron is able to channel in the silicon lattice. Also, at the lower energies of interest for shallow profiles, channeling occurs more easily, further aggravating the simulation difficulty. The original LSS th...

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Section: Description Of New Modeling Approachmentioning

confidence: 99%

mentioning

confidence: 99%

An Improved Approach to Accurately Model Shallow B and BF 2 Implants in Silicon

Tasch

Shin

Park

et al. 1989

J. Electrochem. Soc.

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Results of a SIMS round robin sponsored by ASTM committee E‐42 on surface analysis

Hues

Colton

1989

Surface & Interface Analysis

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The results of a round robin involving the quantitative depth pro& aMlySk of ion-implanted boron in silicon by secondary ion mass spectrometry are reported. This study was a blind analysis; each participant was provided with three samples, a standard for which the implantation dose was known and two other samples of unknown dose. The study compares the accuracy and precision of the quantitative analysis of boron in silicon, background signal levels, detection limits, dynamic range and sputter depth profle shapes obtained using fifteen SIMS instruments (fourteen commercial imtrnments manufactured by five different companies and one home-built system). The quantitative SIMS analysis of boron in silicon, using similar standards, was found to have a relative standard deviation of approximately 10-12%, which also turned out to be the variation in sample homogeneity over the implanted samples, and a relative error of < 10%. Comparison of sputter profile shapes shows a good degree of precision extending over six decades of signal intensity. The highest dynamic range of 6.1 x lo5 and the best detection limit of 3.7 x 10" atoms m-3 were found for analyses using the 'minichip' method of v. Criegern and Weitzel. Results of a test concerning the lateral homogeneity of the depth distribution of the implanted species are presented and d i s c d .

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