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Integration of nanostructures of semiconducting materials such as zinc oxide with flexible substrates represent a great opportunity to obtain unique sensing platform especially for the biomedical market. However, the attractive optical and electrical properties of ZnO are usually obtained by growing or annealing nanostructured films at relative high temperatures (>400 °C), which are not suitable to substrates made of polymeric materials. We demonstrate in this work that high quality ZnO nanostructures can be processed at relative low temperature (<100 °C) by combining low temperature deposition process and XeCl excimer laser (wavelength 308 nm), used to locally anneal and recrystallize ZnO without affecting the underlying polymeric substrate. We obtain unique post-annealed ZnO nanostructures, grown and processed both on rigid and flexible substrates, that show comparable optical and structural properties of ZnO films that are processed at high temperatures. We discuss the effect of the laser energy density on the nanostructure by analyzing the recrystallized ZnO films through photoluminescence and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

By using the spectroscopic ellipsometric technique, we investigated the excimer laser annealing (ELA) effect on the electronic properties of indium tin oxides (ITO) films fabricated by the DC-sputtering method, which is the one of the most commonly known methods for the commercial ITO films. We found that while the ELA process was helpful for enhancing the electronic property of the sputtered films, the degree of the enhancement was not so sizable as the case of the sol-gel films. This result appeared to originate from the difference in the physical properties of the sol-gel and sputtered amorphous films. We also examined the thermal annealing (TA) effect on the sputtered amorphous films in various ambient conditions, and compared their physical properties with those of the TA sol-gel films. [ABSTRACT FROM AUTHOR]

High quality transparent conductive oxides (TCOs) often require a high thermal budget fabrication process. In this study, Excimer Laser Annealing (ELA) at a wavelength of 248 nm has been explored as a processing mechanism to facilitate low thermal budget fabrication of high quality aluminium doped zinc oxide (AZO) thin films. 180 nm thick AZO films were prepared by radio frequency magnetron sputtering at room temperature on fused silica substrates. The effects of the applied RF power and the sputtering pressure on the outcome of ELA at different laser energy densities and number of pulses have been investigated. AZO films deposited with no intentional heating at 180 W, and at 2 mTorr of 0.2% oxygen in argon were selected as the optimum as-deposited films in this work, with a resistivity of 1×10 −3 Ω.cm, and an average visible transmission of 85%. ELA was found to result in noticeably reduced resistivity of 5×10 −4 Ω.cm, and enhancing the average visible transmission to 90% when AZO is processed with 5 pulses at 125 mJ/cm 2 . Therefore, the combination of RF magnetron sputtering and ELA, both low thermal budget and scalable techniques, can provide a viable fabrication route of high quality AZO films for use as transparent electrodes. [ABSTRACT FROM AUTHOR]

Phosphorus that had been implanted into silicon-on-insulator (SOI) substrates was activated using different annealing techniques to investigate phosphorus deactivation at low temperatures. A combination of amorphization and excimer laser annealing (ELA) greatly enhanced phosphorus activation. However, heavy doping with phosphorus reduced the thickness of the amorphous layer. Furnace annealing at 350 °C following ELA induced significant deactivation and the deactivation behavior was similar to that following rapid thermal annealing (RTA). The temperature-dependence of phosphorus deactivation in samples that were implanted with a dose of 5×10 16 cm −2 showed a transition at 400 °C. The deactivation behavior was more sensitive to temperature below 400 °C than above it. Samples with an implantation dose of 5×10 15 cm −2 exhibited only a weak temperature-dependence of deactivation at temperatures above 400 °C, implying that the transition of temperature-dependence is caused by the change of the deactivation mechanism with the phosphorus activation level. [ABSTRACT FROM AUTHOR]

We report on the effect of the excimer laser annealing on the electronic properties of indium tin oxide (ITO) sol–gel films by using spectroscopic ellipsometric technique. We found that the excimer laser annealing effectively induces the crystallization as well as condensation of the sol–gel film. As the laser power increased, the carrier concentration and the relaxation time of photo-annealed films increased, with the bandgap shifting to higher energies. Simultaneously, the extinction coefficient values in the visible region were reduced significantly. We suggest that the excimer laser annealing should be a promising method for low temperature preparation of the ITO film on heat-sensitive substrates via the sol–gel process. [ABSTRACT FROM AUTHOR]

193 nm Excimer laser assisted growth and crystallization of amorphous Si/Ge bilayer patterns with circular structures of 3 μm diameter and around 25 nm total thickness, is presented. Amorphous patterns were grown by Laser induced Chemical Vapor Deposition, using nanostencils as shadow masks and then irradiated with the same laser to induce structural and compositional modifications for producing crystalline SiGe alloys through fast melting/solidification cycles. Compositional and structural analyses demonstrated that pulses of 240 mJ/cm 2 lead to graded SiGe alloys with Si rich discs of 2 μm diameter on top, a buried Ge layer, and Ge rich SiGe rings surrounding each feature, as predicted by previous numerical simulation. [ABSTRACT FROM AUTHOR]

Based on the heat diffusion equation we describe the temperature profile of a silicon nanoparticle thin film on silicon during excimer laser annealing using COMSOL Multiphysics. For this purpose system specific material parameters are determined such as the silicon nanoparticle melting point at 1683 K, the surface reflectivity at 248 nm of 20% and the nanoparticle thermal conductivity between 0.3 and 1.2 W/m K. To validate our model, the simulation results are compared to experimental data obtained by Raman spectroscopy, SEM microscopy and electrochemical capacitance–voltage measurements (ECV). The experimental data are in good agreement with our theoretical findings and support the validity of the model. [ABSTRACT FROM AUTHOR]

Thin amorphous silicon (a-Si) films were crystallized into polycrystalline silicon (poly-Si) by combining solid phase crystallization (SPC) and subsequent excimer laser annealing (ELA). Then thin film transistors (TFTs) were fabricated by using the poly-Si formed in the single and double excimer laser scanned area. The device performance of the TFTs fabricated with the excimer laser energy density of 230 mJ/cm 2 is almost equal for the single and double scanned area. This observation indicates that the overlapping laser irradiation with the laser energy density below 230 mJ/cm 2 does not change the characteristics of TFTs. Based on this result, we discuss the correlation between performance of active matrix organic light emitting display (AMOLED) panels and excimer laser energy density during ELA for SPC treated and non-treated poly-Si films. [ABSTRACT FROM AUTHOR]

Abstract: The use of a combined excimer (XeCl=308nm) laser annealing (ELA) and chemical etching process (dubbed the “LaText” process) to generate textured ZnO:Al thin films suitable for thin-film silicon photovoltaic applications has been previously shown, but the evolution of the material during the laser annealing and texturing steps has not been thoroughly examined. In this work, we examine in detail the evolution of the properties of room-temperature sputtered ZnO:Al thin films during such a process. We reveal (i) the bulk structural changes induced during laser annealing through X-ray diffraction measurements (XRD) and Raman spectroscopy, (ii) the dramatic changes in surface morphology and macroscopic electronic properties before and after each step of the LaText process, through Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Hall effect measurements, and (iii) the exceptional light scattering properties of these films in both air and in a cell configuration, as measured by optical transmission and reflection measurements. In all, we show that the electronic transport properties in the final state are acceptable for thin film PV applications, and the optical properties are exceptional and demonstrate great potential for light-trapping performance for both a-Si:H and µc-Si:H solar cells. [Copyright &y& Elsevier]

Abstract: We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p+-nc-Si:H films without damaging the substrate. [Copyright &y& Elsevier]

Abstract: We present an enthalpy-based model for pulsed excimer laser annealing of crystalline silicon in the melting regime that integrates into the technology computer-aided design (TCAD) suite Sentaurus Process of Synopsys. The currently one-dimensional model includes laser absorption, a transient simulation of the heat flux, melting of the surface layer, and undercooling during recrystallization. To verify the model, its predictions for a laser pulse with a duration of ∼150ns and a wavelength of 308nm were compared to those of a phase-field implementation of melting laser annealing by La Magna et al. The two models show a good agreement for the melt depth, melt duration, and melt front dynamics. In a second step, model predictions were compared to melt depths extracted from SIMS measurements of ion implanted and excimer-laser-annealed silicon samples. They were found to agree within the experimental error. Variation of the beam parameters indicated a strong influence of laser energy density fluctuations on the melt depth. [Copyright &y& Elsevier]

Abstract: UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10nm) and n-doped nc-Si:H(60nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193nm radiation with 25ns pulse length and energy densities ranging from 50mJ/cm2 to 400mJ/cm2 have been calculated. Numerical results allowed us to estimate the dehydrogenation process of the different layers and the diffusion of phosphorous (P) in Si layers as well as their structural modifications as a function of the applied laser energy density. Numerical results are compared with exhaustive characterization of the experimental results. [Copyright &y& Elsevier]

Abstract: Today, the collection of generated charges is a limiting problem for the realization of UV sensors. Indeed, the native silicon oxide of the surface acts as a region of recombination centers . Then, the sensors exhibit a low sensitivity in the UV wavelengths. An approach to overcome this drawback is the realization of a few nanometers thick passivation layer at the surface by creating an ultra-shallow junction (USJ) with a high activation level. The realization of such junctions requires two steps: first, the implantation of dopants which consists in introducing impurities at the surface of the substrate, then the thermal activation of these dopants to obtain the electrical characteristics of the junction. The Plasma Immersion Ion Implantation (PIII) process allows us to implant dopants in a very thin layer (10–20nm) into the silicon substrate . These impurities are located in interstitial sites in the silicon, and need an activation process to modify the electrical properties of the layer. The step is performed by means of an excimer laser annealing process (ELA) to melt a very thin layer of the silicon substrate and then activate the dopants without diffusion. In the framework of the ALDIP project (Laser Activation of Dopants implanted by Plasma Immersion), IBS Company has developed with its partners a cluster to realize these two steps with industrial production rates and cleanliness. Four-point probe measurements and SIMS analyzes have been used to characterize the junctions realized with this process. We have reached a sheet resistance lower than 500Ω/sq for a junction depth of 29nm and an abruptness of 3nm/dec. Nevertheless, electrical measurements on diodes have revealed a significant leakage current of around 10−5 A/cm2, revealing the presence of defects inside the junction. Light Beam Induced Current (LBIC) characterization has shown that these defects are localized at the edge of the laser beam. [Copyright &y& Elsevier]

Abstract: The structural and morphological transformations of TiO2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400°C for 1h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85° was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. [Copyright &y& Elsevier]

Abstract: Excimer laser annealing (ELA) is a widely used technique for producing polycrystalline silicon (poly-Si) thin films. An optical inspection system with simple optical arrangements for rapid measurement of recrystallization results of poly-Si thin films is developed in this study. The recrystallization results after both frontside ELA and backside ELA can be easily visible from the profile of peak power density distribution using the optical inspection system developed with an optimized moving velocity of 0.312mm/s of the specimen. The method of backside ELA is suggested for batch production of low-temperature polycrystalline silicon thin-film transistors due to higher laser beam utilization efficiency and lower surface roughness of poly-Si films. [Copyright &y& Elsevier]

Abstract: Excimer laser annealing (ELA) is frequently employed to fabricate low-temperature polycrystalline silicon films on glass substrate. The grain size and crystallinity of polycrystalline silicon films are significantly affected by the resolidification behavior during ELA. A real-time in situ time-resolved optical measurement system is developed to record the rapid phase transformation process during ELA. The average solidification velocity of liquid-Si is calculated from these optical spectra using MATLAB and Excel softwares. Field emission scanning electron microscopy images reveal maximum grain size of poly-Si films with a diameter of 1μm, which is obtained in the complete melting regime of both frontside ELA and backside ELA. Recrystallization mechanisms of complete melting of Si thin films in frontside ELA and backside ELA are demonstrated. Resolidification scenarios of partial melting, near-complete melting and complete melting in frontside ELA and backside ELA are proposed. [Copyright &y& Elsevier]

Abstract: Excellent ultra-shallow p+n junctions have been formed by thermally treating the BF2 +-implanted Si samples by excimer laser annealing (ELA) at 300–400mJcm−2 with post low-temperature long-time furnace annealing (FA) at 600°C. A junction with a leakage current density lower than 20nAcm−2 and a sheet resistance smaller than 200Ω□−1 can be well achieved. No considerable dopant diffusion is observed by using this low-thermal-budget annealing process. However, by simply using the ELA treatment at 300–400mJcm−2, the resultant junction shows a leakage current density as high as 104 nAcm−2 and a peripheral leakage current density of 103 nAcm−1. The large junction leakage is primarily due to the leakage current generated within the junction region near the local-oxidation-of-silicon (LOCOS) edge, and which is substantially caused by the ELA treatment. The large peripheral junction leakage current density can be significantly reduced to be about 0.2nAcm−1 after a post low-temperature FA treatment at 600°C. As a result, the scheme that employs ELA treatment with post low-temperature FA treatment would be efficient for forming excellent ultra-shallow p+n junctions at low thermal budget. [Copyright &y& Elsevier]

Abstract: Implementation of plasma doping and nanosecond laser annealing in the non-melt regime has shown to hold great promise for the realization of ultra shallow junctions, designed for the sub 45nm node. This work includes extensive simulation of these two emerging techniques using the Synopsys Sentaurus Process software tool, in direct comparison with experimental data for each step involved in the process. Analytical calculations were performed in order to investigate the interaction of the KrF Excimer Laser Annealing and silicon regarding the temperature gradients induced into silicon and the boron diffusion kinetics. On the other hand, analytically obtained surface temperature profiles of each annealing condition, were used as input to KMC calculations of the boron diffusion and activation behavior. Simulation predictions, in accordance with SIMS measurements revealed very limited dopant profile movement (maximum 2.5nm), combined with high levels of electrical activation close to the maximum theoretically predicted ones. As the results obtained by calculations are in consistency with the experimental, it is evident that the combination of both analytical and Kinetic Monte Carlo tools, allows for sufficient physical understanding of the underlying mechanisms for these advanced process steps. [Copyright &y& Elsevier]

Abstract: XeF excimer laser-induced melting and recrystallization of amorphous silicon was investigated using in situ on-line time-resolved reflection and transmission measurements with a nanosecond time resolution. Explosive crystallization was observed for 900Å thick amorphous silicon on SiO2 deposited on non-alkali glass substrate upon 25ns pulse duration of excimer laser by continuous-wave He-Ne probe laser. Three distinct regrowth regimes were investigated on the basis of various excimer laser fluences. Scanning electron microscopy, Raman spectroscopy and atomic force microscopy were used to evaluate the excimer laser-irradiated region of the sample. Grain size, surface roughness and melt duration as a function of various laser fluences are also determined. [Copyright &y& Elsevier]

Abstract: Rare earth oxides are emerging candidates for gate oxide films as they have high dielectric constants as well as promising crystal and electronic structures. Lanthanum oxide is one of them but, even if many of its properties are known, no data exist in literature on its thermal conductivity. In this work, La2O3 thermal diffusivity has been measured by laser flash technique in the temperature range 300 K–1600 K and, from it, its thermal conductivity has been derived. Thermal diffusivity showed a decreasing trend from 2.7⁎10−6 m2/s to 0.7⁎10−6 m2/s while thermal conductivity decreases from 6 W/m/K to 2.1 W/m/K in the studied temperature range. Results have been applied to the thermal analysis of excimer laser annealing of La2O3/Si and a-Ge/La2O3/c-Si structures. [Copyright &y& Elsevier]

Abstract: A novel low-temperature process for the crystallization of silicon is proposed: excimer laser annealing (ELA) of amorphous silicon (a-Si) with a hydrogen-modulation-doped layer (ELHMD). The effects of hydrogen on low-energy crystallization by conventional ELA and by ELHMD were investigated. As the hydrogen concentration increases, the crystallinity of the polycrystalline silicon prepared at a low-energy density improves. Nucleation is enhanced by the energy of desorption of hydrogen from Si–H2 bonds during melting of the Si. In addition, film exfoliation can be suppressed by using hydrogen-modulation-doped a-Si film. H modulation doping has the effect of controlling the presence of nucleation sites in the direction of the film thickness. [Copyright &y& Elsevier]

Abstract: We have used reactive magnetron co-sputtering to grow Zn0.95Co0.05O dilute magnetic semiconductor (DMS) on 400nm thick of (0001) Al2O3 substrate at 600°C. After deposition the films were irradiated by ArF excimer laser (λ =193nm, τ =20ns) source, with energy density equal to 0.4J/cm2 for two shoots. The effects of laser annealing on structural, optical and magnetic properties of Zn095Co0.05O thin films on Al2O3 substrate were investigated using X-ray diffraction (XRD), IR absorption spectra, Raman spectroscopy, atomic force microscopy (AFM) and SQUID magnetometry. XRD analysis showed that the annealed film is textured with c-axis of the wurtzite structure along the growth direction. The IR absorption spectra of the sample showed three absorptions peaks before and after laser annealing due to the transitions between the crystal-field-split 3d levels of tetrahedral Co2+ substituting Zn2+ ions. Raman spectra showed the appearance of an additional mode which is an indicator for incorporation of Co2+ ions into the ZnO matrix. The roughness R ms value of the film evaluated by AFM decreased after laser annealing indicates a good surface topography. Room temperature magnetization measurements performed by SQUID magnetometry showed the presence of ferromagnetism with a saturation magnetization increased after ArF excimer laser annealing. [Copyright &y& Elsevier]

Abstract: The application of the striking electrical and optical properties of amorphous and nano-crystalline silicon in photovoltaic, photonic and nano-electronic devices is attracting increasing attention. In particular, its use both on polymeric substrates and in Integrated Circuit technology for the development of enhanced new devices has shown that processing techniques to produce amorphous hydrogenated and nano-crystalline silicon films avoiding high substrate temperatures are of great importance. A promising strategy to achieve this purpose is the combination of Hot-Wire Chemical Vapor Deposition at 150°C with Excimer Laser Annealing, thus maintaining the substrate at relatively low temperature during the complete process. In this work we present a numerical analysis of Excimer Laser Annealing, performed at room temperature, of a multilayer structure of thin alternating a-Si:H and nc-Si films deposited on glass and grown by Hot-Wire Chemical Vapor Deposition. A set of two different layer thicknesses a-Si:H (25nm)/nc-Si (100nm) and a-Si:H (30nm)/nc-Si (60nm) were analysed for a total structure dimension of 900nm. The aim is to determine the probable temperature profile to achieve controlled localized in depth dehydrogenation. Temperature distribution has been calculated inside the multilayer during the irradiation by a 193nm Excimer laser, 20ns pulse length, with energy densities ranging from 50 to 300mJ/cm2. Calculations allowed us to estimate the dehydrogenation effect in the different layers as well as the structural modifications of the same layers as a function of the applied laser energy. The numerical results have been compared to the experimental ones obtained in similar multilayer structures that have been analysed through Raman spectroscopy and TOF-SIMS in depth profiling mode. [Copyright &y& Elsevier]

Abstract: This work gives an overview of the different developments for silicon germanium (Si1−x Ge x ) from a MEMS post-processing perspective. First, the maximum processing temperature that does not introduce any damage or degradation into the standard characteristics of the CMOS driving electronics is specified. Then, the optimal type of silicon and germanium gas sources and deposition technique that results in an economical process are identified. Next, the selection criteria for a low thermal budget doping method and doping species are discussed. Finally, the advantage and disadvantage for the different approaches implemented for enhancing the physical properties of poly Si1−x Ge x at a CMOS backend compatible temperature are highlighted. It is shown that the optimal method depends on the application requirements and the CMOS technology used for realizing the driving electronics. [Copyright &y& Elsevier]

Abstract: The reduction of complementary metal oxide semiconductor dimensions through transistor scaling is in part limited by the SiO2 dielectric layer thickness. Among the materials evaluated as alternative gate dielectrics one of the leading candidate is La2O3 due to its high permittivity and thermodynamic stability. However, during device processing, thermal annealing can promote deleterious interactions between the silicon substrate and the high-k dielectric degrading the desired oxide insulating properties. The possibility to grow poly-SiGe on top of La2O3//Si by laser assisted techniques therefore seems to be very attractive. Low thermal budget techniques such as pulsed laser deposition and crystallization can be a good choice to reduce possible interface modifications due to their localized and limited thermal effect. In this work the laser annealing by ArF excimer laser irradiation of amorphous SiGe grown on La2O3//Si has been analysed theoretically by a numerical model based on the heat conduction differential equation with the aim to control possible modifications at the La2O3//Si interface. Simulations have been carried out using different laser energy densities (0.26–0.58J/cm2), different La2O3 film thickness (5–20nm) and a 50nm, 30nm thick amorphous SiGe layer. The temperature distributions have been studied in both the two films and substrate, the melting depth and interfaces temperature have been evaluated. The fluences ranges for which the interfaces start to melt have been calculated for the different configurations. Thermal profiles and interfaces melting point have shown to be sensitive to the thickness of the La2O3 film, the thicker the film the lower the temperature at Si interface. Good agreement between theoretical and preliminary experimental data has been found. According to our results the oxide degradation is not expected during the laser crystallization of amorphous Si0.7Ge0.3 for the examined ranges of film thickness and fluences. [Copyright &y& Elsevier]

Abstract: Melting and crystallization scenario of amorphous silicon (a-Si) thin films have been investigated using in situ time-resolved optical reflection and transmission measurements. The explosive crystallization phenomenon is observed using a single-mode continuous wave He–Ne probe laser for thickness of 50 nm and 90 nm a-Si thin films upon 25 ns pulse duration of XeF excimer laser irradiation, respectively. The explosive crystallization phenomenon is easier to observe in the large thickness of a-Si thin films, a sample with pure a-Si microstructure and under longer pulse duration of excimer laser irradiation by time-resolved optical reflection and transmission measurements. [Copyright &y& Elsevier]

Abstract: This work combines plasma doping implantation (PLAD) with laser annealing using excimer laser, for the formation of ultra-shallow junctions. For that purpose, high dose BF3 was implanted in n-type silicon wafers using PLAD. The as implanted material was investigated by high resolution TEM, measured by SIMS and simulated by Monte-Carlo codes. Subsequently, the samples were annealed using a KrF laser source at 248nm with a pulse duration 20ns and different fluence values. Laser annealing completely recrystallizes the amorphous layer as monitored by TEM measurements, fully activates the dopants achieving low sheet resistance values as shown by Van der Pauw measurements and results in box-shaped dopant profiles with movement less than 10nm at the junction depth as measured using SIMS. [Copyright &y& Elsevier]

Abstract: An excimer laser (KrF, 248nm) was used to crystallize barium strontium titanate thin films of thickness 95nm. Numerical simulation was first performed to get an idea about the laser energy suitable for crystallization. Amorphous films deposited by chemical solution deposition were irradiated at different energies with different frequencies (40–l50Hz), laser fluences (100–150mJ/cm2) and pulses (400–1000) while maintaining the substrate at 25 and 250°C. Films were found to crystallize above 100mJ/cm2 in both cases. Films crystallized with substrate temperatures of 250°C were noticed to have less cracks. The microstructure of these films were analyzed with a scanning electron microscope. From the XPS analysis, it is inferred that the top few nanometers have a different structure compared to normal furnace annealed thin films. This top surface layer was found to be dependent on the laser energy used for crystallization. The dielectric constant was found to increase from 60 to 180 for the 95nm thin films on increasing the laser fluence. Films crystallized with 120mJ/cm2 while maintaining a substrate temperature of 250°C have leakage current densities of 1×10 −7 A/cm2 at 1.5V and a dielectric constant of 200. [Copyright &y& Elsevier]

Abstract: Integration of excimer laser annealing (ELA) process for power MOSFET devices is currently studied and evaluated within the frame of the IST project FLASH (Fundamentals and applications of laser processing for highly innovative MOS technology), funded by the European Commission. Final goal of the project is to show that ELA can be industrialized in the context of semiconductor device fabrication. In this work, the recent advancements of the FLASH project are described, including the formation of n+/p source junctions in both one and two dimensions. The experimental results are analysed by using a two-dimensional simulation program, specifically developed by the consortium. The simulation tool allowed a deeper insight of the ELA process and has been successfully used to optimise the process parameters. Finally, data on electrical integrity of the test devices are also presented, showing a yield for optimum ELA conditions up to 84%. [Copyright &y& Elsevier]

Abstract: In the course of a systematic investigation of dynamic, chemical, and laser-induced solid phase epitaxy of α-quartz after ion implantation, we have studied epitaxy and cathodoluminescence emission after 250keV Cs-ion implantation and subsequent pulsed excimer laser treatment in air. Rutherford backscattering channelling analysis showed partial epitaxy for all the laser-irradiated samples; however, no full epitaxy was achieved. The optical properties of these samples were analyzed using cathodoluminescence spectroscopy, giving evidence of five emission bands at 2.42, 2.79, 3.25, 3.65, and 4.30eV photon energy. Their intensity relation to the laser power and retained Cs-ion fraction are discussed and the present results will be compared with those obtained after chemical and dynamic epitaxy of quartz after alkali-ion, Ge, and Ba implantation. [Copyright &y& Elsevier]

Abstract: Line beam excimer laser annealing (ELA) is a well-known technique for thin Si-film crystallization and established in LTPS mass production. With introduction of sequential lateral solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS-techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM-images of process examples are shown in order to demonstrate the viability. [Copyright &y& Elsevier]

Abstract: Excimer laser crystallization of thin film amorphous silicon has become a key technology in manufacturing of high-resolution low-power consumption thin film transistor displays. Lambda Physik and its Beam Delivery Systems Department MicroLas are leading the efforts to develop complete laser-optical system solutions comprising uniformity, productivity and economic aspects of this UV–laser process. This paper will present latest achievements in high-power excimer laser and illuminator design to address the production requirements of thin film crystallization and will look at challenges to meet future requirements. [Copyright &y& Elsevier]

Abstract: The effect of excimer laser annealing (ELA) and rapid thermal annealing (RTA) on B redistribution in B-implanted Si has been studied by secondary ion mass spectrometry (SIMS) and spreading resistance probe (SRP). B has been implanted with an energy of 1keV and a dose of 1016 cm−2 forming a distribution with a width of 20–30nm and a peak concentration of ∼5 × 1021 cm−3. It has been found that ELA with 10 pulses of the energy density of 850mJ/cm2 results in a uniform B distribution over the ELA-molten region with an abrupt profile edge. SRP measurements demonstrate good activation of the implanted B after ELA, with the concentration of the activated fraction (∼1021 cm−3) exceeding the solid solubility level. RTA (30s at 1100°C) of the as-implanted and ELA-treated samples leads to a diffusion of B with diffusivities exceeding the equilibrium one and the enhancement is similar for both of the samples. It is also found that RTA decreases the activated B in the ELA-treated sample to the solid solubility limit (2 × 1020 cm−3). The similarity of the B diffusivity for the as-implanted and ELA-treated samples suggests that the enhancement of the B diffusivity is due to the so-called boron-enhanced diffusion (BED). Possible mechanisms of BED are discussed. [Copyright &y& Elsevier]

Abstract: Excimer laser annealing (ELA) of MOSFET devices is currently studied and evaluated within the frame of the IST project “Fundamentals and applications of laser processing for highly innovative MOS technology” (FLASH), funded by the European Commission. This European consortium aim to demonstrate that ELA can be industrialized in the context of semiconductor device fabrication. The technical achievement of homogeneous irradiation of entire wafers by industrial line beam system set up has been combined with device design solutions, in order to avoid the detrimental effects of the laser beam on device structures and tackle the integration issues, main obstacles for the use of ELA in the semiconductor industry. The launch of ELA, to open a new market segment in the semiconductor industry, implies also the availability of reliable process simulation tools. Therefore, a simulation program based on the phase-field method was produced, fully working and available. [Copyright &y& Elsevier]

A new automated metrology tool using infrared spectroscopic ellipsometry is presented. After a description of the instrument with special attention on the spot size, the instrument specifications are described and one application of the technique related to the IC technology is presented. We show that physical and electrical information on Ultra Shallow Junction formed by Excimer Laser annealing for the sub 100 nm node on silicon on insulator (SOI) and on bulk silicon can be obtained independently. We compare these results with conventional techniques like four points probe and secondary ion mass spectroscopy (SIMS) and show a very good agreement. [Copyright &y& Elsevier]

Gas immersion laser doping (GILD) is a very attractive technique to realize the ultra-shallow and highly doped junctions required by the International Technology Roadmap for Semiconductors (ITRS) for future CMOS technologies. In the present work, gaseous dopant precursors (BCl3) are chemisorbed on the Si surface, and partially incorporated during the melting/recrystallisation of the Si top layer induced by an UV laser pulse (λ=308 nm, pulse duration &ap;25 ns). The resulting thickness and dopant concentration of the doped layer depend on the laser energy density and the number of chemisorption/laser-induced incorporation cycles (up to 200). GILD processed junctions are box-like and exhibit depths ranging from 14 nm to 65 nm, with sheet resistances ranging from &ap;110 to 20 Ω/□ (respectively), dopant concentrations well above the B solubility limit in Si (up to 3×1021 at/cm3) at local thermodynamic equilibrium (LTE) and abruptness of 5–2 nm/decade. Moreover, in situ optical characterization shows the GILD technique capabilities to realize the sub-10 nm thick shallow junctions needed for the sub-40 nm node ITRS predictions. [Copyright &y& Elsevier]

Crystallization by excimer-laser annealing (ELA) for hydrogenated amorphous silicon (a-Si:H) films with low hydrogen content (CH) prepared by catalytic chemical vapor deposition (Cat-CVD) was systematically studied. From optical microscopy images, no hydrogen bubbling was observed during ELA, even without a dehydrogenation process. As the laser energy density was increased to 300 mJ cm−2, the full width at half-maximum of the Raman signal from the crystalline phase decreased to approximately 4 cm−1. This value is almost equal to or even smaller than that reported for polycrystalline Si (poly-Si) films prepared from plasma-enhanced CVD (PECVD) a-Si:H films by ELA so far. The average grain size, estimated from scanning electron microscopy, was approximately 500 nm for CH of 1.3 at.%. On the other hand, the grain size of poly-Si films prepared from PECVD a-Si:H films with a dehydrogenation process was only 200 nm. The technique using Cat-CVD films is expected to be used for fabrication of low-temperature high-mobility thin-film transistors. [Copyright &y& Elsevier]

The rapid control of laser crystallisation during in-line large area flat panel display fabrication using polysilicon (poly-Si) thin-film transistors (TFT’s) is of growing importance.In this work, the microstructural analysis of the laser irradiated area has been studied with atomic force microscopy (AFM) and phase stepping microscopy (PSM), the latter being an automated mode of interference microscopy that allows the rapid and non-destructive measurement of nanometric surface morphology. The evolution of the crystallisation process in amorphous silicon (a-Si) thin films irradiated using large and long duration (200 ns) excimer laser (308 nm) pulses as a function of different key parameters such as the laser fluence, the beam homogeneity and the number of laser shots has been studied. We show that PSM, although having a lower lateral resolution than AFM, is capable of detecting the important super lateral growth (SLG) region.From the comparison of the results obtained by interference microscopy and AFM, the PSM technique has been shown to be an interesting alternative way that could be used for the quantitative calibration of the laser annealing process in an industrial environment. [Copyright &y& Elsevier]

A novel fabrication process for low-temperature (<500 °C) polysilicon thin film transistors (TFTs) is proposed. The main features of such process are: (i) the source and drain contacts formation by deposition and lift-off of doped layers, allowing to eliminate ion-implantation; (ii) the use of a single excimer laser annealing step for active layer crystallization and doping activation. The gradual doping profile, resulting from the adopted contact formation process and further smeared by the laser annealing, enables a drain field reduction, if compared to doping profiles that can be achieved by conventional techniques. This allows a substantial reduction of the “field enhanced” mechanisms, affecting the electrical characteristics of polysilicon TFTs at high source/drain voltages, such as kink effect and leakage current. The present process, thanks to the above mentioned features, can be rather attractive for polysilicon TFTs applications. [Copyright &y& Elsevier]

The KrF excimer laser annealing of phosphorous implanted polycrystalline silicon (poly-Si) films had been investigated completely. Resistors were fabricated to measure sheet resistance of poly-Si film. The interference effect, heat absorption of capping oxide as well as transformation of poly-Si grain size during laser annealing were reported. Depending on the carrier concentrations, poly-Si exhibits different sheet resistance behavior when the excimer laser fluence is higher than the full-melt threshold fluence. The sheet resistance of poly-Si film has an abnormal increase from 5×104 to 4×106 Ω/□ when the excimer laser energy is higher than full-melt threshold energy. [Copyright &y& Elsevier]

Electrical properties in the subthreshold region are studied in two types of field effect transistors: laser crystallized-polysilicon thin film transistors (LC-TFTs) and solid phase crystallized-polysilicon thin film transistors (SPC-TFTs). For LC-TFT the active layer is crystallized by using one shot of a very large area excimer laser with a fluence of 600 mJ/cm2, whereas the active layer for SPC-TFT is crystallized by a thermal annealing at 600 °C in vacuum. LC polysilicon layer exhibits a higher degree of crystallinity than the SPC one.Electrical measurements on the TFTs are performed from room temperature to 120 °C. The analysis of the transfer characteristics shows that the subthreshold current is thermally activated with a different gate voltage dependence for each type of TFTs. The electrical behavior in the subthreshold region is correlated with the quality of the polysilicon active layer. For LC-TFT, conduction is mainly due to thermal emission of carriers over intergranular barrier energy, and it is convenient with a discrete distribution of defects in the active layer, mainly located at the grain boundaries. On the other hand, for SPC-TFTs, a mechanism of multiple-trapping and/or generation/recombination process of carriers from defects, rather uniformly distributed in the active layer, predominates in the electrical conduction. [Copyright &y& Elsevier]

Recently, all-solid-state lithium batteries have attracted great attention due to their safe operation without risk of explosion under high operating voltage. However, integrating all solid layers on flexible polymer substrate has been hampered by conflicts between the high crystallization temperature and the endurable temperature of the polymer substrate. In this work, we present a simple fabrication method for all-solid-state flexible lithium batteries that are directly integrated on a polymer substrate. Using excimer laser annealing technique, we are able to selectively crystalize the amorphous cathode layer grown on top of the polymer platform without any damage to the substrate. Our flexible battery is bendable up to a curvature radius of 9 mm without mechanical breakdown, and has an initial capacity of 20 μA h μm−1 cm−2 at a 0.2 C-rate. Our approach using laser annealing provides new opportunities for integrating all-solid-state lithium thin film batteries on a broader range of platforms. • The first report of fabrication flexible batteries directly on polymer substrate. • All components are solid-state thin film offering long term stability. • A simple excimer laser irradiation is used to selectively crystalize thin films. • Batteries exhibit an initial capacity of 20 μA h μm−1 cm−2 with voltage above 4.5 V. • This flexible batteries can be a new power platforms for microelectronics. [ABSTRACT FROM AUTHOR]

• Laser irradiated IZO film achieved a low electrical resistivity of 3.55 × 10−4 Ωcm. • Laser irradiated IZO film also achieved a high work function of 5.4 eV. • Inserting a SiO 2 layer prevented cracking on the surface when laser irradiation. We have developed an excimer laser annealing method to achieve low electrical resistivity (ρ) and a high work function in amorphous In 2 O 3 :Zn (IZO) films on polyethylene terephthalate (PET) substrates. The effect of excimer laser irradiation of the films on crack formation, electrical properties (ρ , carrier concentration, and Hall mobility), and work function were investigated. KrF excimer laser irradiation produced cracks in the surface of the IZO films on PET as a result of thermal expansion of the PET substrate. By inserting an amorphous SiO 2 layer as a heat barrier between the IZO layer and PET substrate, crack formation was prevented. Moreover, it was found that the work function of IZO film could be controlled by the laser fluence and repetition rate. Irradiation of a 150-nm-thick amorphous IZO film on a SiO 2 -coated PET substrate achieved a low ρ of 3.55 × 10−4 Ω cm and a high work function of 5.4 eV due to the reduction of oxygen and carbon while maintaining a flat surface. [ABSTRACT FROM AUTHOR]

Abstract: We have performed a comparative study of B re-distribution and electrical activation after excimer laser annealing (ELA) of B and BF2 implanted Si. Chemical B concentration and electrical activation profiles were measured by secondary ion mass spectrometry (SIMS) and spreading resistance profiling (SRP), respectively. SIMS data demonstrate that the presence of F does not influence significantly the re-distribution of B during ELA. A dramatic contrast, however, can be observed in the electrical activation of the dopant in the B and BF2 implanted samples. While almost 100% electrical activation of B occurs in the B implanted samples, only 20–50% of the dopant can be activated by ELA in the BF2 implanted sample. Possible mechanisms causing the deactivation of B in the BF2 implanted samples after ELA are discussed. [Copyright &y& Elsevier]

Abstract: (Ba,Sr)TiO3 (BST) thin film with a perovskite structure has a potential for the practical applications in various functional devices. Normally, the BST thin films derived from sol–gel and sputtering are amorphous or partially crystalline when processed below 700 °C. For the purpose of integrating BST thin film directly into system-on-package (SoP), it is necessary to process the BST film below 350 °C. The electrical properties of low-temperature crystallized BST film were studied in this paper. The BST thin films have been crystallized at 300 °C by excimer laser annealing (ELA). The BST films were exhibited in a single perovskite phase and have well-defined electrical properties such as high dielectric constant, low dielectric loss and low leakage current density. As a result, we demonstrated crystallized BST thin film which has permittivity of 143, dielectric loss of 0.028 and leakage current density of 0.9 μA/cm2 below 300 °C. [Copyright &y& Elsevier]