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Peaker A.R.,University of Manchester | Markevich V.P.,University of Manchester | Hamilton B.,University of Manchester | Parada G.,Semilab | And 8 more authors.
Physica Status Solidi (A) Applications and Materials Science | Year: 2012

Electronic grade Czochralski and float zone silicon in the as grown state have a very low concentration of recombination generation centers (typically <10 10 cm -3). Consequently, in integrated circuit technologies using such material, electrically active inadvertent impurities and structural defects are rarely detectable. The quest for cheap photovoltaic cells has led to the use of less pure silicon, multi-crystalline material, and low cost processing for solar applications. Cells made in this way have significant extrinsic recombination mechanisms. In this paper we review recombination involving defects and impurities in single crystal and in multi-crystalline solar silicon. Our main techniques for this work are recombination lifetime mapping measurements using microwave detected photoconductivity decay and variants of deep level transient spectroscopy (DLTS). In particular, we use Laplace DLTS to distinguish between isolated point defects, small precipitate complexes and decorated extended defects. We compare the behavior of some common metallic contaminants in solar silicon in relation to their effect on carrier lifetime and cell efficiency. Finally, we consider the role of hydrogen passivation in relation to transition metal contaminants, grain boundaries and dislocations. We conclude that recombination via point defects can be significant but in most multi-crystalline material the dominant recombination path is via decorated dislocation clusters within grains with little contribution to the overall recombination from grain boundaries. Achieving high efficiency in low cost silicon solar cells is a key goal in the quest for effective renewable energy sources. In this Feature Article the authors have studied the recombination process in solar silicon involving defects and impurities which degrade the cell efficiency. Lifetime mapping measurement using microwave detected photoconductivity decay shows that the parasitic recombination is concentrated in specific regions of multi-crystalline ingots. Localised Laplace Deep Level Transient Spectroscopy has been used to distinguish isolated point defects, small precipitate complexes and decorated extended defects. It is concluded that in most multi-crystalline materials the dominant recombination path is via decorated dislocation clusters within grains with little contribution to the overall recombination from grain boundaries. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Borland J.,J.O.B. Technologies | Tallian M.,Semilab | Kosztka D.,Semilab | Pap A.,Semilab | And 5 more authors.
18th International Conference on Advanced Thermal Processing of Semiconductors, RTP 2010 | Year: 2010

Boron 200eV 1E15/cm 2 p+ Ultra Shallow Junctions with various PAI (Ge, Xe & In) and HALO (As & Sb) implantation activated by msec laser annealing (1220°C to 1350°C) were studied using Junction Photo Voltage (JPV) and Modulated Photo Reflectance (MPR). JPV and MPR provided information about junction quality; dopant activation, junction capacitance, residual implant damage and junction leakage. Highest p+ junction quality and best p+ dopant activation was achieved with laser annealing temperatures >1300°C. The results with Sb-HALO were worse than with As-HALO. For HALO implants junction leakage was controlled by direct band to band tunneling while for no HALO it was controlled by end of range residual PAI defects. The high junction leakage (exceeding E-5 A/cm 2) could lead to unreliable Rs and junction capacitance determination. © IEEE.

Duru R.,STMicroelectronics | Le-Cunff D.,STMicroelectronics | Nguyen T.,STMicroelectronics | Barge D.,STMicroelectronics | And 3 more authors.
ASMC (Advanced Semiconductor Manufacturing Conference) Proceedings | Year: 2013

This paper describes a study performed to evaluate in a manufacturing environment the Model Based Infrared Reflectometry (MBIR) technique for the monitoring of the Boron doping in epitaxial SiGe:B layers and Phosphorus doping in epitaxial SiC:P layers. MBIR correlation to comparative techniques is demonstrated on multiple wafer sets, including product wafers on bulk silicon and FD-SOI (Fully Depleted Silicon On Insulator) substrates. The results obtained demonstrate that MBIR is a suitable measurement technique for the in-line monitoring of doping for epitaxial SiGe:B and SiC:P layers. © 2013 IEEE.

Hoglund J.,SEMILAB | Kiss Z.,SEMILAB | Nadudvari G.,SEMILAB | Kovacs Z.,SEMILAB | And 3 more authors.
Journal of Micro/Nanolithography, MEMS, and MOEMS | Year: 2014

The three-dimensional (3-D) integrated circuit relies on the stacking of multiple two-dimensional integrated circuits into a single device using through silicon vias (TSVs) as the vertical interconnect. There are a number of factors driving 3-D integration, including reduced power consumption, resistance-capacitance delay, formfactor, as well as increased bandwidth. One of the critical process steps in all 3-D processes is stacking, which may take the form of wafer-to-wafer, chip-to-wafer, or chip-to-chip bonding. This bonding may be temporary, such as can be used for attaching a device wafer to a handle wafer for thinning, or permanent, incorporating direct metal bonds or solder bumps to carry signals between the wafers and oxide bonds or underfill in the regions without conductors. In each of these processes, it is critical that the bonding is executed in such a way to prevent the occurrence of voids between the layers. This article describes the capabilities of infrared (IR)microscopy to detectmicrometer size voids that can form in optically transparent blanket media such as oxide-to-oxide permanent bonding, benzocyclobuten permanent bonding, or temporary adhesive bonding laminate interfaces. The infrared microscope is described, and the measurement results from a bonded void wafer set are included. The wafers used to demonstrate the tool's capabilities include programmed voids with various sizes, densities, and depths. The results obtained from the IR microscopy measurements give an overview of the technique's capability to detect and measure voids as well as some of its limitations. © The Authors.

Ayerden N.P.,Koç University | Stehle J.-L.,SEMILAB | Holmstrom S.,Koç University | Urey H.,Koç University
International Conference on Optical MEMS and Nanophotonics | Year: 2012

MEMS LGI FTIR system is developed and optimized. Out-of-plane deflection >500μm is obtained at 350Hz using piezoelectric and acoustic actuation. Optical system is optimized to obtain the best spectrum. 20μm SOI film thickness is measured. © 2012 IEEE.

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