Modeling the impurity profile in an ion-implanted layer of an IGFET for the calculation of threshold voltages

AbstractThe diffusion of ion-implanted dopants in silicon during rapid thermal annealing is modeled using the finite difference method.The change in impurity profile for an initial Pearson IV boron implant is negligible(less than 1 % change in junction depth) when the peak annealing temperature(TP ) is less than 1050 °C and its duration is shorter than 20 seconds. The dopant redistribution becomes significant(greater than 25 % change in junction depth) when Tp is greater than 1200 °C and its duration is longer than 40 seconds.The heatup and cooldown portions of the transient annealing cycle are found to have little effect on dopant redistribution provided that their rates are higher than 120 °C per second.

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Electron Diffraction Analysis of Microtwin Structures in Regrown (III) Silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054765 ◽

1982 ◽

Vol 40 ◽

pp. 460-461

Author(s):

P. Ling ◽

R. Gronsky ◽

J. Washburn

Keyword(s):

Electron Diffraction ◽

Ion Implantation ◽

Diffraction Analysis ◽

Diffraction Pattern ◽

Direct Consequence ◽

The Other ◽

Electron Diffraction Analysis ◽

Defect Microstructures ◽

Ion Implanted

The defect microstructures of Si arising from ion implantation and subsequent regrowth for a (111) substrate have been found to be dominated by microtwins. Figure 1(a) is a typical diffraction pattern of annealed ion-implanted (111) Si showing two groups of extra diffraction spots; one at positions (m, n integers), the other at adjacent positions between <000> and <220>. The object of the present paper is to show that these extra reflections are a direct consequence of the microtwins in the material.

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Defects in ion implanted silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109070 ◽

1978 ◽

Vol 36 (1) ◽

pp. 386-387

Author(s):

J.A. Lambert ◽

P.S. Dobson

Keyword(s):

Defect Structure ◽

Dislocation Loops ◽

Frank Loop ◽

Burgers Vector ◽

Temperature Range ◽

Perfect Dislocation ◽

Contrast Analysis ◽

Image Position ◽

Ion Implanted

The defect structure of ion-implanted silicon, which has been annealed in the temperature range 800°C-1100°C, consists of extrinsic Frank faulted loops and perfect dislocation loops, together with‘rod like’ defects elongated along <110> directions. Various structures have been suggested for the elongated defects and it was argued that an extrinsically faulted Frank loop could undergo partial shear to yield an intrinsically faulted defect having a Burgers vector of 1/6 <411>.This defect has been observed in boron implanted silicon (1015 B+ cm-2 40KeV) and a detailed contrast analysis has confirmed the proposed structure.

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A technique to prepare cross-sectional TEM specimens of semiconducting devices

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014508x ◽

1986 ◽

Vol 44 ◽

pp. 742-743

Author(s):

A. K. Rai ◽

P. P. Pronko

Keyword(s):

Thin Films ◽

Surface Region ◽

Sample Surface ◽

Specific Region ◽

Cross Sectional ◽

Thin Sections ◽

The Past ◽

Device Structures ◽

Ion Implanted

Several techniques have been reported in the past to prepare cross(x)-sectional TEM specimen. These methods are applicable when the sample surface is uniform. Examples of samples having uniform surfaces are ion implanted samples, thin films deposited on substrates and epilayers grown on substrates. Once device structures are fabricated on the surfaces of appropriate materials these surfaces will no longer remain uniform. For samples with uniform surfaces it does not matter which part of the surface region remains in the thin sections of the x-sectional TEM specimen since it is similar everywhere. However, in order to study a specific region of a device employing x-sectional TEM, one has to make sure that the desired region is thinned. In the present work a simple way to obtain thin sections of desired device region is described.

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Microstructure studies of tungsten silicide schottky contacts on Gaas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126445 ◽

1987 ◽

Vol 45 ◽

pp. 328-329

Author(s):

Yih-Cheng Shih ◽

E. L. Wilkie

Keyword(s):

Thermal Stability ◽

Field Effect Transistors ◽

Schottky Contact ◽

Schottky Contacts ◽

Excellent Thermal Stability ◽

Barrier Heights ◽

Gaas Substrates ◽

Film Adhesion ◽

Threshold Voltages ◽

Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

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Preparation of Backthinned Ceramic Specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117881 ◽

1985 ◽

Vol 43 ◽

pp. 182-183

Author(s):

A. T. Fisher ◽

P. Angelini

Keyword(s):

Electron Microscopy ◽

Analytical Electron Microscopy ◽

Vacuum System ◽

Back Surface ◽

Surface Microstructure ◽

Ion Milling ◽

Near Surface ◽

Depth Profiles ◽

Analytical Electron ◽

Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

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