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The study describes the development of a thermal model for flash lamp processing of 3C-SiC on silicon substrates in the millisecond regime, the FLASiC process. The kinetics of melting and regrowth is also considered.

The influence of high dose ion irradiation through amorphous surface layers in single crystalline 6H-SiC at elevated temperatures was analyzed. Quantification for irradiation at 500 degrees Celsius was conduced on material swelling, subsequent densification and surface erosion. Ion beam induced recrystallization was examined in the temperature range from 300-1300 degrees Celsius. The findings indicate that perfect epitaxial regrowth in (0001)-oriented 6H-SiC cannot be achieved by ion irradiation at elevated temperatures.

The influence of SiO2 and SiNx cover layers on the dopant distribution as well as microstructure of high fluence Ga implanted Si after thermal processing is investigated. The annealing temperature determines the layer microstructure and the cover layers influence the obtained Ga profile. Rapid thermal annealing at temperatures up to 750°C leads to a polycrystalline layer structure containing amorphous Ga-rich precipitates. Already after a short 20?ms flash lamp annealing, a Ga-rich interface layer is observed for implantation through the cover layers. This effect can partly be suppressed by annealing temperatures of at least 900°C. However, in this case, Ga accumulates in larger, cone-like precipitates without disturbing the surrounding Si lattice parameters. Such a Ga-rich crystalline Si phase does not exist in the equilibrium phase diagram according to which the Ga solubility in Si is less than 0.1 at. %. The Ga-rich areas are capped with SiOx grown during annealing which only can be avoided by the usage of SiNx cover layers. [ABSTRACT FROM AUTHOR]

The effect of rare-earth clustering in dielectric media on the electroluminescence (EL) intensity, the charge trapping and the EL quenching was investigated using the example of Tb and Eu-implanted SiO2 layers. It was shown that the increase in the REOX cluster size induced by an increase in the furnace annealing temperature resulted in an increase in the concentration of electron traps with capture cross sections from 2×10-15 to 2×10-18 cm2. This is probably associated with an increase in the concentration of oxygen deficiency centers as well as with strained and dangling bonds in the SiO2 matrix which leads to an enhanced scattering of hot electrons and a decrease in the excitation cross section of the main EL lines of RE3+ ions. For the main EL lines of Tb3+ and Eu3+ ions the relation of the EL quenching to negative and positive charge generation in the SiO2 was considered. It was demonstrated that in case of REOX nanoclusters with small sizes (up to 5 nm) the EL quenching process can mainly be explained by a defect shell model which suggests the formation of negatively charged defect shells around the nanoclusters leading to a Coulomb repulsion of hot electrons and a suppression of the RE3+ excitation. At high levels of the injected charge (more than 2×1020 e/cm2) a second stage of the EL quenching was observed which was contributed to a positive charge accumulation in the SiO2 at a distance beyond the tunneling distance from the SiO2[Single_Bond]Si interface. In case of Eu-implanted SiO2 the quenching of the main EL line of Eu3+ is mostly correlated with positive charge trapping in the bulk of the dielectric. A model of EL quenching of the main Eu3+ line is proposed. [ABSTRACT FROM AUTHOR]

Heavily p-type doped Ge layers were fabricated by 100 keV Ga implantation and subsequent flash lamp annealing for 3 ms in the temperature range between 700 and 900 °C. For comparison, some samples were annealed in a rapid thermal processor for 60 s. Ga fluences of 2×1015, 6×1015, and 2×1016 cm-2 were chosen in order to achieve Ga peak concentrations ranging from values slightly below the equilibrium solid solubility limit of 4.9×1020 cm-3 up to 3.5×1021 cm-3 which corresponds to a maximum Ga content of about 8 at. %. The structure of the doped layer and the Ga distribution were investigated by Rutherford backscattering spectrometry in combination with ion channeling, cross-sectional electron microscopy, and secondary ion mass spectrometry. Temperature dependent Hall effect measurements were carried out in order to determine the electrical properties of the Ga-doped Ge layers. It is shown that by flash lamp annealing Ga diffusion into the bulk can be completely avoided and the Ga loss by outdiffusion from the surface is reduced. The lowest sheet resistance of 36 Ω/sq. was achieved for the medium Ga concentration annealed at 900 °C. The best Ga activation values are 73%, 60%, and 24% for the three Ga fluences under investigation. The Ga activation is correlated with the layer regrowth. Incomplete epitaxial regrowth as observed in some samples leads to lower activation. [ABSTRACT FROM AUTHOR]

Systematic evolution of the 400 nm electroluminescence (EL) with increasing flash lamp annealing (FLA) temperature from 800 to 1100 °C in an Er-doped Ge-rich metal-oxide semiconductor structure is presented. No significant change in the 1535 nm Er EL is observed with increasing FLA temperature. Enhancement of the 400 nm EL decay time with rising FLA temperature is found to be associated with recrystallization of the damaged Ge clusters in the absence of Ge outdiffusion. The 400 nm EL quenching with continuous charge injection process is also discussed within the device operation time. [ABSTRACT FROM AUTHOR]

The anomalous wear-out phenomena of Eu-implanted metal-oxide-semiconductor devices were investigated. It will be shown that in contrast to other rare earth elements the electroluminescence (EL) intensity of Eu-implanted SiO2 layers can rise under constant current injection before the known EL quenching will start. Under certain circumstances, this rise may amount up to two orders of magnitude. The EL behavior will be correlated with the microstructural and electrical properties of the devices. Transmission electron microscopy and Rutherford backscattering spectroscopy were applied to trace the development of Eu/Eu oxide clusters and the diffusion of Eu to the interfaces of the gate oxide layer. The hydrogen profile within the SiO2–SiON interface region was determined by nuclear reaction analysis. Current-voltage characteristics, EL decay times, and the progression of the voltage and the EL spectrum with increasing charge injection were measured to study charge and trapping phenomena in the oxide layer to reveal details of the EL excitation mechanism. A first qualitative model for the anomalous life time behavior is proposed. [ABSTRACT FROM AUTHOR]

Using combined electroluminescence (EL) and photoluminescence (PL) studies we establish that the energy transfer process from the Er3+ to the Ge-related oxygen-deficiency centers (GeODCs) plays the key role in enhancing the 404 nm EL intensity in Ge-rich SiO2. Er doping induced structural modification does not appear to be relevant, which is deduced from the 404 nm PL quenching with increasing Er concentration, implying a gradual loss of GeODCs. In contrast to PL, the 404 nm EL intensity increases by 0.3% Er doping followed by a gradual decrease in intensity for higher Er concentrations, which is described in terms of a competition between the energy transfer process and the gradual segregation of Er due to the destruction of GeODCs with Er doping. This fact is further discussed in the light of ab initio molecular orbital calculations. [ABSTRACT FROM AUTHOR]

High quality 3C-SiC nanocrystallites were epitaxially formed on (100) Si wafers covered by a 150 nm thick SiO2 capping layer after low dose carbon implantation and high temperature annealing in CO atmosphere. Carbon implantation is used to introduce nucleation sites by forming silicon-carbon clusters at the SiO2/Si interface acting as nucleation sites for the growth of 3C-SiC nanocrystallites. The formation of the nucleation clusters as well as the morphology, the size, and the density of the nanocrystals were systematically studied by conventional and high resolution transmission electron microscopy. The nanocrystallites were developed following two different modes of growth: The first develops facets along the <100> crystallographic direction giving tetragonal grains and the second facets along the <110> direction resulting in elongated nanocrystallites. The formation mechanism of the nanocrystallites and the strain related with them are also discussed. [ABSTRACT FROM AUTHOR]

The impact of rapid thermal annealing (RTA) in producing samples by sequential implantation of Si and Er ions into a 200 nm SiO2 layer combined with different annealing cycles as well as the corresponding room-temperature visible and infrared photoluminescence (PL) have been studied. The Er-related PL intensity at 1533 nm for the samples prepared by implanting Si with subsequent annealing, followed by Er implantation, and final annealing (type I) was found to be stronger than the one produced similarly but without the first annealing step (type II). In fact, the 1533 nm peak intensity in the optimized RTA processed sample is comparable to the PL yield of the furnace-annealed sample. Moreover, the excitation wavelength (405 nm) was found to be suitable for exciting the Si=O related point defects in the SiO2 layer and can provide a PL band with a maximum at ∼580 nm. While this band was further intensified in the presence of Si nanocrystals (Si NCs), it became weaker by introducing additional Er3+ ions with a concomitant rise of the 1533 nm Er PL, confirming the visible range pumping of Er3+. The detailed spectral analyses suggest that the 580 nm band is the result of the excitation/deexcitation mechanism in molecule such as states in the Si=O or the Si=O state mediated recombination of carriers in Si NCs according to the model proposed by [Wolkin et al., Phys. Rev. Lett. 82, 197 (1999)]. The samples were further characterized by transmission electron microscopy and Fourier-transform infrared spectroscopy. The time-resolved PL measurements and a modeling by rate equations were also performed to determine and justify the energy migration mechanism from Si NC to the neighboring Er3+. [ABSTRACT FROM AUTHOR]

Flash lamp annealing in the millisecond regime of heteroepitaxial silicon carbide on silicon structures involves melting the silicon below the SiC layer, but the deep faceted nature of the liquid-solid interface leads to unacceptable surface roughness. This paper describes a method of controlling melting by implanting a high dose of carbon at a controlled depth below the Si/SiC interface, which significantly alters the melting characteristics of the silicon. This technology has also been applied to SiC and Si multilayer heterostructures. Results confirm the effectiveness of this approach for increasing surface uniformity, making liquid phase processing compatible with standard device fabrication techniques. A thermal model has also been developed to describe this process and results indicate that the theoretical work is consistent with the experimental evidence. The model is a valuable tool for predicting the onset of melting, maximum temperatures, and process windows for controlled liquid phase epitaxy. [ABSTRACT FROM AUTHOR]

A flash lamp has been used to uniformly anneal large wafers with diameters approaching 100 mm. The equipment applies a pulse, with duration of 3–20 ms, resulting in large transient thermal gradients in the wafer. In this paper, we present separate models of the thermal reaction of this process and its effect upon the mechanical behavior, in order to predict stresses and shape changes, and to capture practical phenomenon. We further use the model to follow changes in the expected response consequent on altering process conditions, such as preheating and pulse duration, as well as exploring important issues associated with scaling to large wafer sizes. This work presents an initial description of the thermomechanical response of wafers to flash lamp annealing in the millisecond time regime and is therefore fundamental to the use of this technique in the fabrication of semiconductor devices. [ABSTRACT FROM AUTHOR]

Al supersaturated SiC layers (5×1020 Al cm-3) were produced by multienergy, high-dose ion implantation into 6H- and 4H-SiC. Several implantation schemes with varying implantation sequence and temperature were investigated. In dependence on the implantation conditions damaged single-crystalline, amorphous, or nanocrystalline layers were formed. The layer morphology and Al distribution in the as-implanted state as well as structural changes and related Al redistribution after high-temperature annealing (1500–1700 °C) were characterized by cross-sectional transmission electron microscopy, Rutherford backscattering spectrometry in combination with ion channeling, atomic force microscopy, and secondary-ion mass spectrometry. Remarkable Al redistribution effects have been found after annealing of Al supersaturated SiC. During high-temperature annealing Al atoms in excess to the solid solubility (2×1020 Al cm-3) tend to precipitate in single-crystalline SiC whereas they diffuse out in amorphous or nanocrystalline SiC. Redistribution of Al with concentration below the solid solubility is governed by transient enhanced diffusion which can be controlled by the annealing scheme. Amorphization of SiC is advantageous in the case of Al doping to levels higher than the solid solubility because it prevents Al precipitation during annealing and helps to form boxlike Al profiles with smooth plateau and abrupt edge. [ABSTRACT FROM AUTHOR]

The article presents a comparative study of the furnace and the flash-lamp annealing temperature dependent variation that is observed in the room temperature 1.52 [mu]m Er photoluminescence. The different factors that determine the photoluminescence intensity in both the cases are also determined.

Systematic evolution of the electroluminescence (EL) with increasing flash lamp annealing (FLA) temperature in an Er-doped Ge-rich metal-oxide semiconductor structure is described. The enhancement of the EL decay time with rising FLA temperature is associated with recrystallization of the damaged Ge clusters in the absence of Ge outdiffusion.

Combined electroluminescence (EL) and photoluminescence (PL) studies have shown that the energy transfer processes from the [Er.sup.3+] to the Ge-related oxygen-deficiency centers (GeODCs) have played a major role in enhancing the 404 nm EL intensity in Ge-rich Si[O.sub.2]. The studies have shown that the 404 nm EL intensity is increased by 0.3% Er doping followed by a gradual decrease in intensity for higher Er concentrations, which is described in terms of a competition between the energy transfer processes and the gradual segregation of Er due to the destruction of GeODs with Er doping.

Combined microstructural and electroluminescence (EL) investigations of the Er-doped Ge-rich Si[O.sub.2] layers are used for showing that the Ge-related oxygen-deficiency centers (GeODCs) are situated at the Ge nanocrystal/Si[O.sub.2] interface. Ge concentration dependent quenching of the maximum EL intensity and the peak shifting toward higher Er concentration are explored with respect to the reduction of the surface-to-volume ratio with increasing nanocrystal size.

A low dose carbon implantation and high temperature annealing in CO atmosphere were applied to grow epitaxially high quality 3C-SiC nanocrystallites on (100) Si wafers covered by a 150 nm thick Si[O.sub.2] capping layer. Conventional and high resolution transmission electron microscopy were used to gain insight into formation of the nucleation of silicon-carbon clusters at the Si[O.sub.2]/Si interface as well as the morphology, the size, and the density of the inamoratas.

A study is carried out to determine the impact of rapid thermal annealing (RTA) in producing samples by sequential implantations of Si and Er ions into a 200 nm Si[O.sub.2] layer. The results from time-resolved photoluminescence (PL) measurements and rate equations model justify the energy migration mechanism from Si NC to the neighboring [Er.sup.3+].

The furnace and flash-lamp annealing (FLA) temperature dependent variation in the room temperature 1.53 μm Er photoluminescence (PL) from Er-doped Ge-rich SiO2 layers is investigated. The appearance of the 1.53 μm Er PL is discussed in the framework of the phonon-assisted fluorescent resonant energy transfer from Ge-related luminescence-centers (LCs) to the Er3+. Detailed analyses suggest that in case of FLA the decrease in the 1.53 μm Er PL intensity is governed by the temperature dependent recrystallization of Ge nanoclusters, while for furnace-annealing it is associated with the reduction in the LC-Er3+ coupling due to Ge out-diffusion and the formation of Er-rich clusters with increasing temperature. [ABSTRACT FROM AUTHOR]

Using combined microstructural and electroluminescence (EL) investigations of the Er-doped Ge-rich SiO2 layers, it is established that the Ge-related oxygen-deficiency centers (GeODCs), which are associated with the 407 nm light emission, are situated at the Ge nanocrystal/SiO2 interface. Electrically driven energy transfer from the Er3+ to GeODCs causes an increase in the 407 nm EL intensity. It reaches a maximum before quenching with increasing Er concentration due to the crystalline-to-amorphous transition of Ge nanocrystals. Ge concentration dependent quenching of the maximum EL intensity and the peak shifting toward higher Er concentration are discussed in terms of the reduction of the surface-to-volume ratio with increasing nanocrystal size. [ABSTRACT FROM AUTHOR]