Capability of impurity gettering by thin polycrystalline films on the backside of silicon wafer was evaluated by minority-carrier diffusion length. Cu was gettered easily during usual cooling after high temperature annealing. On the other hand, intentional slow cooling or low temperature annealing was necessary for effective Fe gettering. The gettering efficiency for Fe increased with lowering the annealing temperature when Fe was diffused sufficiently. From the quantitative consideration of Fe gettering, we propose the model of impurity gettering based on the chemical equilibrium of impurity reaction in polysilicon films. It was also expected that gettering efficiency increased with the thickness of polysilicon film.

Experiments on the intrinsic gettering of Cr in p-type Czochralski-grown Si including lamp pulse annealings have been carried out. Transmission Electron Microscopy observations of both oxide and metallic precipitates on cross-sectional specimens, as well as quantitative results about the electrically active metal depth-profiles, using Deep Level Transient Spectroscopy measurements, are presented. We have observed that a lamp pulse (1200 °C/5 s) applied prior to a three-step gettering cycle produced a strong retardation of the oxygen precipitation, and consequently an inhibition of the Cr bulk precipitation during the nucleation step. Besides, it was observed that the Cr-precipitates formed in the bulk during the oxygen nucleation step were highly unstable upon a post-gettering 2–4 s lamp pulse at 1000 °C, whereas the same lamp pulse did not produce a significant re-dissolution of Cr-precipitates formed during the oxide precipitate growth step. The reversibility of the intrinsic gettering of Cr upon a post-gettering lamp pulse thus critically depends on the oxide precipitate growth rate during the gettering process.

IR and DLTS studies of H-implanted Si crystals are performed. It is shown that H is a bistable impurity: it has an equilibrium site at a T-site for H+ and H- and at a BC-site for H°. The mechanisms of H-passivation of defects and shallow and deep impurities are discussed.

The electrical and optical properties of defects introduced by Reactive Ion Etching (RIE) in the near surface region of Si after dry etching with various gases and plasma conditions is studied with spreading Resistance (SR), photoluminescence (PL), and capacitance-voltage profiling (C-V). Plasma etching in chlorine and fluorine based gases produce donors at the surface in both n-type and p-type, Czochralski and float-zone silicon. Isochronal annealing reveals the presence of two distinct regions of dopant compensation. The surface damage region is confined to 1000 Å and survives heat treatment at 400°C, while the defect reaction region extends ≥ 1 μm in depth and recovers by 250°C. A comprehensive picture of the interstitial defect reactions in RIE silicon is completed. The interstitial defects, Ci and Bi, created in the ion damaged near surface region, undergo recombination enhanced diffusion caused by the presence of ultraviolet light in the plasma, resulting in the long range diffusion into the Si bulk. Subsequently, the interstitial atoms are trapped by the background impurities forming the defect pairs, CiOi, CSCi, or BiOi, which are observed experimentally. The depth of the diffusion-limited trapping and the probability of forming specific pairs depends on the relative concentrations of the reactants, oxygen, carbon or boron, present in the bulk material.

A new approach to investigate low energy defect formation and annealing in a crystal is developed, based on experimental observations of the total number of interstitials. The model is applied to damage in crystalline silicon caused by low energy implantation of Si-atoms during 40eV implants at 300°Kand 685°K. The model has two versions, analytical and computational, and includes two kinds of diffusing species, self-interstitials and vacancies, their interaction, surface motion of the growing crystal, and a constant source of defects. The source was calculated using a modified TRIM code (TRJMCSR). The focal point of the analysis is the number of interstitials per ion dose surviving at the end of the deposition time (damage to dose ratio or DDR, which is found to be an informative quantity and can be calculated for more sophisticated models including precipitation.

In this study, using oxide breakdown voltage and time-dependent-dielectric breakdown measurements, thermal wave modulated reflectance and chemical etching/optical microscopy, we investigated effects of Si ion implantation upon formation of D-defects and thin gate oxide integrity. Our data show that addition of Si ion implantation with a dose of up to 1013 ions/cm2 improves oxide integrity if the implantation is done at a certain step just before sacrificial oxidation in the Mb DRAM process. However, no improvement in oxide integrity is observed when the same implantation is done on the virgin wafer surfaces at the start of the same Mb DRAM process. We discuss our hypothesis that the improvement in oxide integrity is due to a reduction in the D-defect density in the near-surface region of the wafer.

Electronic defects were introduced at and around the Si-SiO2 interface by exposing thermally-oxidized silicon samples to a 16 keV Si ion beam in an ion implanter. The oxide thickness was 350 Å. Following Si self-implantation, hydrogenation was carried out at room temperature by a 400 eV hydrogen ion beam from a Kaufman source. Experimental results obtained from the admittance-voltage-frequency measurements of the metal-oxide-silicon structures indicated significant passivation of the ion-beam-induced defects.

Vacancy type defects introduced by As+, P+, Si+ and B+ ion implantations into Si (100) single crystals were studied by a variable-energy positron beam. Depth distributions of the defects were obtained from measurements of Doppler broadening profiles of the positron annihilation as a function of incident positron energy. The results showed that this technique is sensitive not only to a vacancy type defect but to formation of amorphous regions. The defects introduced by lower doses were identified as vacancy clusters from isochronal annealing experiments. By higher doses such as 5×1014 /cm2, amorphous layers were formed for 150KeV As+, 150KeV P+, and 200KeV Si+ ions, and it was not formed for 80KeV B+ by the dose of 5×1015 /cm2. These results are consistent with the calculated critical doses. In the case of B+, pre-amorphous formation was observed with higher ion beam current over 5mA and a dose of 5×1015 /cm2.

Vacancy-type defects in ion implanted Si were studied by a monoenergetic positron beam. The depth-distributions of the defects were obtained from measurements of Doppler broadening profiles of the positron annihilation as a function of incident positron energy. The results showed that a size of vacany-clusters introduced by 150-keV P+-ion implantation was found to be smaller than that introduced by 2-MeV P+-ion implantation. This was attributed to an overlap of collision cascades in low-energy (150 keV) ion implanted specimens. From isochronal annealing experiments for 80-keV B+- and 150-keV P+-ion implanted specimens, the defected region was removed by 1200 °C annealing, however, for 2-MeV P+-implanted specimen, two-types of oxygen-vacancy complexes were found to coexist even after 1200 °C annealing.

The effect of ultraviolet (UV) irradiation on the minority-carrier surface recombination lifetime (τs) in silicon wafers with native or thermal oxide was studied with a noncontact laser/microwave photoconductance (LM-PC) technique. The τs greatly increases in samples with native oxide after the irradiation. The dominant factor for the τs change can be negative charges created by photo-injected electrons in the surface area. On the other hand, the irradiation decreases τs in silicon with thermal oxide. The τs decrease is due to the generation of carrier recombination centers with an energy level around 0.2eV at the Si-SiO2 interface.

Indium Phosphide (InP) based multilayer structures are becoming increasingly important in the semiconductor industry with optoelectronic applications being the main growth area. Mesa type structures with finely controlled width and etch angle, often form the building blocks for many of these photonic devices. Traditional wet etching techniques have often proved to be inadequate for the required anisotropie removal of material. This paper presents the results of etching semi-insulating InP (100) using a combination of an Argon ion beam and a reactive gas, CCl2F2 (Freon 12). It was found that the etch rate was enhanced by increasing the ion energy and by the addition of CCl2F2. Auger electron spectroscopy revealed that the increased etch rate was accompanied by an increase in the surface indium concentration and at low ion beam energies carbon build-up retarded the etch rate. The optimum etch angle to fabricate 3μm waveguides was found to be 22° to the surface normal, however Schottky contacts to these structures were unsuccessful.

We have studied the damage and strain produced in Ge (100) single crystals by implantation of various doses of 300 keV 28Si ions at room temperature. The analyzing tools were x-ray double-crystal diffractometry, and MeV 4He channeling spectrometry. The damage induced by implantation produces positive strain in Ge (100). The maximum perpendicular strain and maximum defect concentration rise nonlinearly with increasing dose. These quantities are linearly related with a dose-independent coefficient of ∼ 0.013 for Ge (100) single crystals implanted at room temperature. The results are compared with those available for Si (100) self-implantation. We have also monitored the strain and defects generated in pseudomorphic Ge0.1Si0.9/Si (100) films induced by room temperature 28Si ion implantation. It is found that the relationship between the strain and defect concentration induced by ion implantation is no longer a simple linear one.

Using void-related compensation in Al-implanted GaAs, high-resistivity isolation regions that are thermally stable to high temperatures (> 700 °C) are demonstrated. The high-temperature thermal stability of the isolation regions allows the simplification of device processing in which a single high-temperature anneal (e.g., at 900 °C) can be used to activate the implant dopants in the device-active regions, and simultaneously to convert the Al-implanted regions highly resistive for electrical isolation. Other advantages of using void-related isolation will also be discussed.

In this paper results of a study of electron irradiation induced extended defect generation in doped silicon is presented. The irradiations are performed in-situ with 1 MeV electrons in a high voltage transmission electron microscope. Preferential generation of extended defects is observed in certain areas of the sample which can be correlated with well defined dopant concentration levels. The defect growth kinetics is studied as a function of the irradiation temperature and dose and the type and concentration of dopant.

After the first irradiation experiment some of the samples received a second electron irradiation, during which shrinkage and even complete annihilation of the previously generated defects can be observed. The observed results are interpreted on the base of point defect reactions.

A series of CuInSe2 single crystals which were grown by the vertical Bridgman technique have been implanted with oxygen and xenon ions. These implants tend to cause a change from n to p-type conductivity and an enhancement of the photoconductivity. We present HREM and SIMS characterisation of the microstructural effects caused by high dose ion implants on CuInSe2. We also correlate our data with calculated ion implant profiles. In addition, we show that CuInSe2 thin foils can undergo significant degradation under the electron beam irradiation conditions which are commonly encountered in electron microscopes.

We have used high resolution transmission electron microscopy to study the formation of end- of- range defects after pre- amorphization due to Ge+ - implantation and subsequent furnace annealing at temperatures below 550 C. It is shown that depending on the annealing conditions two types of extrinsic stacking faults (SFs) are formed, i.e. {113}- defects or Frank- type {111} SFs. We present a scheme allowing the controlled deposition of Si self- interstitials into {113}- defects, which can be removed more easily than Frank type SFs during subsequent RTA under constraints of low thermal budget.

DLTS studies of electronic states and properties of the selfinterstitial in α-irradiated p-Si and n-Si are performed. The injection-enhanced annealing is observed for two traps E2 (Ec -0.39 eV) and El (Ec -0.26 eV) in p-Si. The annealing of E2 and E1 are simultaneous with the growth of hole traps connected with vacancy (V), Ci and Ali. It is concluded that the observed electronic levels belonq to different charge states of silicon selfinterstitial. The conclusion is confirmed by the differences of cross sections of the formation of Ali and Ci, by the influence of the zero and reverse bias conditions on the introduction rate and optical annealing of the E2 state in p-Si as well as by DLTS spectra of n-Si.

The effect of phosphorous ion implantation and/or rapid thermal treatment on the behaviour of Schottky barrier elect-rophysical characteristics formed on the plane (100) of n-GaP epitaxial layer is discussed. Even though the implantation and post implantation rapid annealing lead to the generation of deep recombination centers in the bulk, the dominant mechanism of current transport across the barrier structure becomes thermo-ionic - like in initial samples. The analysis of the behaviour of forward current-voltage characteristics, steady state capacitance-voltage characteristics and DLTS data allow to conclude that the obtained reduction of forward current after ion im- plactation can be attributed to an increase of effective potenia! barrier height.

High-energy ion-implantation is one of the roost critical processing steps regarding the formation of defects in mono-crystalline silicon. High- as well as low-doses implanted at various energies can result in relatively high residual defect concentrations after post-implantation annealing.

Before annealing, the crystal lattice strain is mainly caused by the point defects. After annealing, the accommodation of substitutional impurities is the main origin of the residual lattice strain. High-Resolution X-ray Diffraction (HRXD) has been frequently used for the characterization of these structures. Dislocation loops formed during the high temperature step, however, cause enhanced diffuse X-ray scattering, which can dominate the measured X-ray intensity in conventional HRXD.

Triple axis diffractometry is used in this study to analyze the size, type and location of defects in a boron implanted and rapid thermally annealed silicon sample.

In proton-bombarded InP single crystals the fluence-dependent production of vacancy-type radiation defects and their annealing behaviour are studied. The results are interpreted using measurements of the total defect concentration, the carrier concentration and the infrared absorption.