摘要:

An ion-beam mixing technique is used to fabricate ultrashallowp+/njunctions. In this method, a thin boron layer is first sputter deposited onto the Si wafer surface. Then a 10–40 keV Ge ion beam or−3 kVAr plasma source ion implantation (PSII) is used to knock the boron atoms into the Si substrate by means of ion-beam mixing. For the thin (0.7 nm) boron layers used in this effort, a selective etch for the removal of boron is unnecessary. Sub-100 nmp+/njunctions have been realized with this method. Numerical simulations, performed to predict the recoiled boron profiles, show good agreement between the simulated and measured data.

ISSN:1071-1023    

DOI:10.1116/1.589823

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A new two-dimensional junction delineation technique named Auger voltage contrast (AVC) is described. AVC is a mapping tool that indicates the dopant type of each point of the cross-sectioned surface by measuring the Auger electron energy shifts that mirror the workfunction differences caused by the built-in junction, i.e., caused by Fermi level differences betweenn- andp-doped silicon. AVC makes use of the dual capabilities of field emission Auger electron spectroscopy instrumentation for spectroscopy at each pixel and for high spatial resolution. A theoretical examination is made of the important practical aspects of this previously observed Auger energy line shift, in particular the effect of surface states on the Fermi level position and the effect of beam-induced electron-hole pair creation and transport. AVC results obtained from cross-sectioned metal–oxide–semiconductor structures are shown to have good agreement with both theory and with one-dimensional secondary ion mass spectroscopy and spreading resistance probe profiles from the same sample. A fast and efficient algorithm has been devised which fits the Auger SiLVVspectrum to that of a reference spectrum obtained from a region of known doping, so that it is possible to make a calculation of the energy shift at each pixel with resolution on the order of 50 meV and in a way that speeds analysis and minimizes storage size.

ISSN:1071-1023    

DOI:10.1116/1.589824

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The possibilities of diffusion from polymer spin-on films have been investigated for the purpose of obtaining shallow junctions in Si, GaAs, InP, and InGaAs. Compared to the conventional diffusion techniques, diffusion from polymer spin-on films is simpler and more controllable. The peculiarities of the method are associated with a uniform distribution of the dopant atoms in the three-dimensional network of the polymer chains. The possibilities have been demonstrated for control of the atomic concentration of B in silicon and of Zn in III–V compounds (from1021to1017 cm−3) and for obtaining shallowp-njunctions; for example, a junction depth of 40 nm has been obtained in silicon. Diffusion conditions have been analyzed which provide a near-entire activation of the impurity. Moreover, gettering the defects and the background impurities by the spin-on film in the near-surface region of the semiconductor has been investigated.

ISSN:1071-1023    

DOI:10.1116/1.589825

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

This study presents an empirical implantation damage model on the basis of the“+1”model, describing the defect profile as a function of implantation energy, dose, and species. The model implies that the defect profile generated by ion implantation is very sensitive to the implantation condition especially at low doses and energies. This sensitivity is not accounted sufficiently for by the existing model, and that it can be effectively argumented by the proposed dependencies of D.PLUS. To validate the model, the extracted dependencies were applied to process and device simulations for our 0.35 μm complementary metal–oxide–semiconductor technology. An excellent agreement between simulation and measurement was obtained in the reverse short channel effect as well as in the drain induced barrier lowering and the body effect, which indicates that both vertical and lateral profiles are accurately described by this model.

ISSN:1071-1023    

DOI:10.1116/1.589934

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have characterized the effect of implant parameters on the characteristics of boron-implanted silicon prepared by plasma doping. The thickness of the amorphous layer was monitored using Rutherford backscattering spectrometry, transmission electron microscopy, and double crystal x-ray diffraction. At low plasma implant pulse biases (2 kV), both dose rate and pulse repetition rate (10 Hz to 1 kHz) were found to have a negligible effect on the generation of the surface amorphous layer. At higher voltages (5 kV), the thickness of the amorphous layer increased with the pulse repetition rate but was apparently not sensitive to the dose rate. The sheet resistance after annealing correlated strongly with the increasing thickness of the surface amorphous layer formed at 5 kV. From these results, we conclude that an increase in pulse repetition rate has a stronger effect on the formation of the surface amorphous layer than does dose rate.

ISSN:1071-1023    

DOI:10.1116/1.589826

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The alteration of the shape of one-dimensional, two-dimensional (2D), and three-dimensional (3D) range distributions with growing dose as well as the extension of amorphous zones formed at high doses is studied for 15 keVBF2+and 30 keVP+implantations into (100)Si using the dynamic binary collision code Crystal-TRIM. The range and damage profiles are calculated for the area97.74 (parallel to [010])×97.74 (parallel to [001]) nm2at the target surface irradiated by the ion beam and surrounded by impenetrable masks. The change of the shape of the 2D and 3D distributions in the lateral direction is less pronounced than in the depth direction. At low doses the lateral profile branches are determined by rechanneled particles, at high doses the enhanced dechanneling is the reason for the increased lateral straggling. The latter effect is responsible for the relatively large lateral extension of the amorphous zone beneath the masks. The simulated depth profiles of boron and phosphorus and the predicted thickness of the amorphous layer are in good agreement with experimental data.

ISSN:1071-1023    

DOI:10.1116/1.589828

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The electrical characteristics of shallow junction devices are often dependent on tightly controlled ion implants for their performance and yield. However, concerns exist over the ability of existing in-line metrology tools to accurately verify low energy implants, and therefore, determine whether the ion implanter is in control before committing product to it. This article will explore the capabilities of the Therma-Probe TP500, the Tencor OmniMap RS75, and secondary-ion-mass spectroscopy to measure low energy ion implants done on an Applied Materials xR-LEAP with energies10 keVand below, doses of1.0E15–3.0E15 cm−2,and both boron and arsenic species.

ISSN:1071-1023    

DOI:10.1116/1.589818

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have used scanning tunneling microscopy and spectroscopy (STM/S) to study multiplepnjunctions on cross-sectional surfaces of both Si and GaAs devices. The spectroscopy results indicate thatpnjunctions can be resolved at the nanometer scale by using the two-dimensional STS technique. STM is also used to identify Zn dopants on GaAs(110) surfaces. A detail dopant location identification method is presented.

ISSN:1071-1023    

DOI:10.1116/1.589829

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We will report a variation of the scanning capacitance microscopy for two-dimensional delineation of semiconductor charge carrier profiles based on the measurement of the local Schottky contact capacitance. When a metal probe is brought into contact with a semiconductor, a space-charged depletion region and therefore a capacitor is formed at the junction. By applying a small ac voltage, the voltage derivative of the contact capacitance can be measured with a lock-in amplifier. The amplitude of the derivative signal is a function of the carrier concentration, and the sign gives the type of carrier. We have carried out the local contact capacitance–voltage measurements on standard doping concentration samples and two-dimensional (2D) carrier concentration profiling on device structures. The results demonstrate that the contact capacitance measurement is capable of quantitative 2D characterization of semiconductor devices. These preliminary results also demonstrate that this technique, when used as a method for carrier profiling, is relatively insensitive to the sample surface condition.

ISSN:1071-1023    

DOI:10.1116/1.589830

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

To help correlate scanning capacitance microscope measurements of silicon with uniformly doped concentrations, model capacitance curves are calculated and stored in a database that depends on the probe-tip radius of curvature, the oxide thickness, and the dopant density. The oxide thicknesses range from 5 to 20 nm, the dopant concentrations range from1017to1020 cm−3,and the probe-tip radius of curvature is set to 10 nm. The cone-shaped probe is oriented normal to the sample surface, so that the finite-element method in two dimensions may be used to solve Poisson’s equation in the semiconductor region and Laplace’s equation in the oxide and ambient regions. The equations are solved within the semi-classical quasistatic approximation, where capacitance measurement depends only on the charge due to majority carriers, with inversion and charge trapping effects being ignored. Comparison with one-dimensional-related models differs as much as 200% over the given doping range. For shallow gradient profiles satisfying quasiuniformity conditions, the database is used directly to find the doping profile. Converting a512×512point image takes less than 2 min.

ISSN:1071-1023    

DOI:10.1116/1.589831

出版商:American Vacuum Society    

年代:1998

数据来源: AIP