The effects of Ti and Co silicidation on P+ ion implantation damage in Si have been investigated. After silicidation of unannealed 40 keV, 2×1015 cm-2 P+ implanted junctions by rapid thermal annealing at 900°C for 10–300 seconds, secondary ion mass spectrometry depth profiles of phosphorus in suicided and non-silicided junctions were compared. While non-silicided and TiSi2 suicided junctions exhibited equal amounts of transient enhanced diffusion behavior, the junction depths under COSi2 were significantly shallower. End-of-range interstitial dislocation loops in the same suicided and non-silicided junctions were studied by planview transmission electron microscopy. The loops were found to be stable after 900°C, 5 minute annealing in non-silicided material, and their formation was only slightly effected by TiSi2 or COSi2 silicidation. However, enhanced dissolution of the loops was observed under both TiSi2 and COSi2, with essentially complete removal of the defects under COSi2 after 5 minutes at 900°C. The observed diffusion and defect behavior strongly suggest that implantation damage induced excess interstitial concentrations are significantly reduced by the formation and presence of COSi2, and to a lesser extent by TiSi2. The observed time-dependent defect removal under the suicide films suggests that vacancy injection and/or interstitial absorption by the suicide film continues long after the suicide chemical reaction is complete.

The defect annihilation in CZ-crystal was first detected during the process of oxygen out-diffusion, by the positron measurements with a variable-energy beam. The defects, which were related to oxygen atoms such as oxygen cluster, were mainly annihilated at the high temperature, ex., 1150°C. The defect concentration was decreasing down to one tenth, compared with that for an as-grown crystal.

An arsenic doped polysilicon emitter structure is widely used as an important technology for high speed BiPolar and BiCMOS VLSI devices. The electrical behavior of such emitters is dictated to a large degree by the structure of the polysilicon/silicon interface and the extent of any interfacial oxide. In particular the contact resistance of n+ and p+ diffused regions of the polysilicon is sensitive to the interfacial structure. The microstructure of the polysilicon, in addition to the interface, dictates the junction depth and electrical properties and is determined by the deposition conditions and subsequent doping and annealing processes. The interface itself is defined largely by the cleaning procedure and the initial stages of the deposition process. In this paper we report the effects of process variables, such as deposition temperature, doping and annealing times and temperatures and pre-cleans on the microstructure and electrical properties of poly-emitters.

This paper reports the variation of carrier concentration depth profile in Si-implanted channel conductive layers of liquid- encapsulated-Czochralski- technique (LEC) grown GaAs crystals, the Vth scattering amplitude variation and the averaged Vth variation before and after phospho-silicate-glass (PSG) cap annealing of high-dose-Si-ion implanted crystal layers. Furthermore, the PSG-cap-annealing Vth variation difference between the As-rich LEC crystal and the near-stoichiometric LEC crystal is presented. These results, and carrier depth profile of Si-implanted active layers in LEC GaAs crystals through model of implanted Si atom move (like diffusion) and Si atom capture of a crystal lattice and siteing on lattice are discussed.

Poly-buffered local-oxidation of silicon + trench-isolation (PBLT) is a technique being explored for device isolation. In an earlier study, we had reported the presence of dislocations associated with a combination of high-dose (∼5E14 cm2) phosphorous implants and PBLT isolation. In the present study, the behavior of extended defects present in the structures is analyzed in greater detail. The origin and behavior of the defects is modelled to explore potential mechanisms to explain the observations. Implantation induced dislocation-loops interact with stress fields associated with PBLT isolation-trenches. Some of the implant loops (in the presence of a stress field) transform to dislocation sources which then create glide dislocations in the structures. Strategies for defect engineering are discussed, including reducing implant-induced damage (lowering the implant dose) or reducing stress fields (by moving the edge of the implanted region away from the trench). Defect densities can be reduced or eliminated.

The influence of the rapid thermal annealing (RTA) in comparison with that of the standard furnace annealing (FA) on the electrical parameters and photoluminescence (PL) of Czochralski silicon (Cz Si) subjected to neutron irradiation at various temperatures has been studied. The role of the irradiation temperature on the annealing behaviour of electrical parameters in Cz Si has been established. The possibility of getting neutron transmutation doped (NTD) Cz Si having the calculated resistivity by means of the RTA is shown.

The incorporation of small amounts of fluorine has been found to improve the properties of MOS devices. In this paper, some of these results will be reviewed, several techniques to introduce fluorine will be described, the distributions of F resulting from these processes will be shown, and the possible mechanisms leading to the improved MOS device reliability will be discussed.

Random telegraph signals can be seen in the conductivity of submicron MOSFETs due to capture and emission from individual SiO2 defects. They show activated capture times, temperature dependent energy levels as well as a complex scattering behaviour. It is shown how 1/f noise in large MOSFETs arises naturally from the properties of these defects and how models based on this understanding can be constructed. 1/f noise is shown to be a poor tool for the study of the traps due to the loss of information associated with averaging over many active signals.

Deep level acceptor and donor centers are created in III-V materials by energetic ion bombardments. The controlled introduction of these centers by selective area implantation can be used to provide electrical and optical isolation of neighbouring devices. We will contrast the implant isolation characteristics of GaAs and AlGaAs with materials such as InP and InGaAs, and also with the ternary compounds InGaP and AllnP, for which there has previously been little information. In all of these materials the as implanted resistivity is controlled by hopping conduction processes, with p « e×p (T 0.25). Post-implant annealing can be used to achieve resistivities of > 108 Ωcm in initially highly doped material provided the implant doses are correctly chosen. These defect engineered regions may be made many microns deep by using overlapping multiple-energy keV implants or a single MeV implant. In the latter case a nearly flat damage profile can be achieved over depths typical of HBT, SEED or long-wavelength laser epitaxial thicknesses. Examples of these devices which rely on controlled introduction of deep level defects for their operation will be given.

The effects of intentional metal contamination on silicon charge-coupled device imagers are reported. Such imagers are both sensitive to and provide sensitive measures of the presence of metals in the fabrication process. High-purity iron, cobalt, nickel, copper, palladium, and gold were deliberately introduced into the device wafers just before the last high temperature step. Metals were found to cause both electrical defects and distinctive imaging defects.

We find that transition metals can be effectively removed from device regions by internal gettering, but that this gettering can be defeated by a fast cool-down. Gold, however, is poorly gettered.

Specific situations where defects have a positive impact on the properties of semiconductors are examined. In a first category are ranged defects used as probes for characterizing materials. Then semiconductors with high concentration of defects like low temperature GaAs and porous Si are discussed. This is followed by cases where direct use is made of the defect properties (optical, pressure…). Finally several possibilities for defect engineering of materials are reviewed.

We report a comparison of the characteristics of germanium- silicon base heterojunction bipolar transistors fabricated using mesa- etched and ion- implanted processes. The base currents of both device structures are dominated by peripheral currents associated with the plasma- SiO2 covered junction edge. After an implant damage anneal at 800 or 900 C, the ion- implanted process exhibited the lowest base currents. There was no evidence of strained layer relaxation even for the 900 C anneal.

We report drain-current (Id) deep level transient spectroscopy (DLTS) spectra and liquid-encapsulated-Czochralski-technique (LEC) GaAs crystal effect on low-frequency-oscillation (LFO) of wide gate (400-μm) Si-implanted GaAs metal- semiconductor field- effect- transistors (MESFETs). In the range of this experiment we could not find distinguishing DLTS peaks surely to be linked with Id-LFO of the MESFETs. Stoichiometric-melt growth LEC-boules showed relatively large Id-LFO phenomena. As-rich-melt growth LEC-boules showed tolerance to Id-LFO. We conclude that Id-LFO is not directly linked to deep centers themselves but interaction between deep centers and potential profiles and electrons. Stability of potential profile or band profile depends on “pinning’ center, which affects Fermi-level or quasi-Fermi-level stability. ‘Pinning’ center such as EL2s of ‘LEC GaAs crystals” is essential.

We contrast the stability under bias-aging conditions of GaAs/AlGaAs HBTs utilizing highly Be- or C-doped base layers. Devices with Be doping display a rapid degradation of dc current gain and junction ideality factor. At 200°C, a 2 × 10 μm2 Be-doped device (4 × 1019cm−3 base doping) operated at a current density of 2.5 × 104 A. cm−2 shows a decrease in gain from 16 to 1.5 within 2h. Under the same conditions a C-doped device with even higher base-doping (7 × 1019 cm−3) is stable over periods of 36h, the longest time we tested our structures. The degradation of Be-doped devices is consistent with the mechanism of recombination-enhanced diffusion of interstitials into the adjoining layers. Similar results are obtained with Zn-doped devices. Since C occupies the As sub-lattice rather than the Ga sublattice as with Be and Zn, it is not susceptible to reaction with Ga interstitials injected during growth or bias-aging.

The electrical and optical properties of Indium-Tin-Oxide (ITO) films, deposited by radio frequency (r.f.) magnetron sputtering, were studied. ITO films, when deposited using optimum sputtering conditions, were reproducibly prepared with resistivity as low as 1.5 × 10−4 Ω-cm and optical transmissivity higher than 80% over the wavelength range of interest. Device stability when ITO is used as a replacement for polysilicon as a gate electrode in silicon charge-coupled device (CCD) image sensors was also studied. After an anneal process at 950 °C in N2 the device degraded. The degradation can be attributed to the generation of oxide charge and interface states in the ITO/SiO2/Si system.

Electronic properties of originally homogeneous samples of (Hg, Cd)Te, CuInSe2 and (CuAg)InSe2 have been modified on a local scale, in a stable manner, at room temperature, by reverse biasing of small area Schottky contacts on them. This is shown, after the bias voltage is lifted, by I-V measurements and by Electron Beam Induced Current scans. The creation of a clear diode-like, and, in the case of (CuAg)InSe2, transistor-like structure, in the vicinity of the Schottky contact, on a scale of about hundred um, could be explained by electromigration of electrically active ions and by the simultaneous generation of point and line defects. The latter type of defects is revealed for (Hg,Cd)Te by chemical etch, after application of the field.

The mechanism of improvement in gate oxide integrity (GOI) characteristics by H2 annealing in CZ-grown Silicon wafers was investigated. Grown-in defects that are considered to degrade GOI and which can be detected correlatively as 0.1 μm level size pits appearing after SC-1 cleaning, decrease drastically by H2 annealing, while other inert gases, i.e., N2 and Ar, do not exhibit such effect. Besides, H2 annealing shrinks or extinguishes oxygen precipitates significantly, while other gases do not. On the other hand, oxygen outdiffusion is exactly the same among H2, N2 and Ar annealing. From these results, it was concluded that the dominant mechanism for GOI characteristics improvement by H2 annealing is due to decomposition of the grown-in defects having Si-O bonding by the reduction reaction between Si-O bonding and hydrogen, and not due to a mere thermal decomposition enhanced by oxygen outdiffusion.

In this paper we shall look at a technique, known as impurity free vacancy diffusion (IFVD) for selectively altering the optoelectronic response of quantum well material after growth with a view to monolithic device integration. We will discuss the mechanism, practical considerations and some possible applications.

Epitaxial growth of III/V compounds with tight band gap engineering is essential for the realization of efficient optoelectronic devices. Using MOVPE, high quality materials have been grown with anomalous low band gap energy. The order/disorder phenomena and their relation to the band gap energy in the GalnP/AlGalnP system are reported. The effect of the growth parameters on the ordered phase and the band gap Eg will be presented by using TEM and PL characterizations. The growth models will be discussed. The importance of the ordering phenomena will be illustrated by short wavelength laser application, the emission wavelength being as low as 650 ran at 300 K. And a possible future laser structure will be proposed.

The discovery of strong visible photoluminescence at room temperature from porous silicon has triggered new hope that light-emitting devices compatible with existing Si-technology might become possible. We first review the luminescence behavior observed in silicon-based materials such as amorphous Si, microcrystalline Si, or SiO2. We then critically discuss the present model for the luminescence from porous silicon based on quantum confinement in view of the growing experimental evidence for the importance of both hydrogen and oxygen to obtain efficient luminescence from this material. We propose an alternative explanation based on the presence of siloxene (SieO3H6) in porous silicon which is corroborated by experimental results obtained with photoluminescence, Raman and IR spectroscopy. An important aspect is that siloxene can be prepared by methods different from anodic oxidation, and one particular technique will be described together with possible ways to tune the luminescence energy.