This book provides a comprehensive survey of the technology of flash lamp annealing (FLA) for thermal processing of semiconductors. It gives a detailed introduction to the FLA technology and its physical background. Advantages, drawbacks and process issues are addressed in detail and allow the reader to properly plan and perform their own thermal processing. Moreover, this books gives a broad overview of the applications of flash lamp annealing, including a comprehensive literature survey. Several case studies of simulated temperature profiles in real material systems give the reader the necessary insight into the underlying physics and simulations. This book is a valuable reference work for both novice and advanced users.
"In recent years, many technologies have come forward to address the display industry's increasing demand for improved TFT performance over a-Si:H. Low Temperature Polycrystalline Silicon (LTPS) is one such material which has been extensively researched due to its high mobility and high TFT current drive. Flash Lamp Annealing (FLA) is a technique which is potentially capable of forming LTPS on large glass substrates, thus reducing cost and increasing throughput compared to raster-scan Excimer Laser Annealing (ELA) which is inherently slow and relatively complex. Polycrystalline silicon with grain size of 10's of microns has been shown using this technique. NMOS and PMOS TFTs with a top gate coplanar structure have been fabricated on display glass which showed very promising results as described below. A SiO2 capping layer was deposited on etched a-Si mesas, which was then used as screen oxide for source/drain ion implantation. Substrate heating at 525°C was implemented to reduce thermal loss during the FLA exposure. The implanted a-Si mesas were FLA exposed with 20 kW/cm2 power for 250 μsec, which yielded large-grain size. The TFTs fabricated had a best-case channel mobility of 380 cm2/V-sec and 143 cm2/V-secs for NMOS and PMOS, respectively. This work presents the first demonstration of CMOS TFTs using the FLA process."--Abstract.
Denise Reichel studies the delicate subject of temperature measurement during lamp-based annealing of semiconductors, in particular during flash lamp annealing. The approach of background-correction using amplitude-modulated light to obtain the sample reflectivity is reinvented from rapid thermal annealing to apply to millisecond annealing. The author presents a new method independent of the lamp operation to obtain this amplitude modulation and derives a formula to describe the process. Further, she investigates the variables of the formula in depth to validate the method’s suitability for background-corrected temperature measurement. The experimental results finally proof its power for elevated temperatures.
The thermal processing of materials ranges from few fem to seconds by Swift Heavy Ion Implantation to about one second using advanced Rapid Thermal Annealing. This book offers after an historical excursus selected contributions on fundamental and applied aspects of thermal processing of classical elemental semiconductors and other advanced materials including nanostructures with novel optoelectronic, magnetic, and superconducting properties. Special emphasis is given on the diffusion and segregation of impurity atoms during thermal treatment. A broad range of examples describes the solid phase and/or liquid phase processing of elemental and compound semiconductors, dielectric composites and organic materials.
"As displays continue to increase in resolution and refresh rate, new materials for thin film transistors (TFTs) are required. Low temperature polycrystalline silicon (LTPS) formed by excimer laser annealing (ELA) has been very successful and has been implemented in small displays, but cost and scalability issues prevent it from entering larger display products. Currently LPTS TFTs are top-gate structures due to manufacturing challenges associated with crystallizing thin film silicon when a thermally conductive gate is under portions and insulating glass under others. Bottom-gate devices offer the benefit of higher breakdown voltage, better dielectric-semiconductor interface quality, and direct access to the back-channel region for interface trap passivation. The ability to fabricate bottom-gate devices would allow for different integration and design schemes and is a prerequisite for double gate structures. Flash lamp annealed (FLA) LTPS is an attractive method to expand the size of displays that use high mobility TFTs due to its scalability and parallel production nature. In this work bottom-gate LTPS TFTs were fabricated via FLA with indium tin oxide (ITO), a transparent conductive oxide, used as the gate electrode. A p-channel TFT with 4 [micron] channel length crystallized with a FLA energy of 4.4 J/cm2 for 250 [micro]s demonstrated a low-field mobility of 190 cm2/(Vs), a subthreshold slope of 325 mV/dec, on/off state ratio of seven orders of magnitude, and a threshold voltage of -5.4 V. A dielectric failure mechanism was identified that compromised the transistor operation under high drain bias and an alternative dopant introduction techniques were proposed to mitigate this issue. An effect due to the transduction of optical energy from the field to thermal energy under the channel via the gate was observed. Details of the FLA crystallization process, device fabrication, and electrical characteristics will be presented."--Abstract.
This book explains why SiC is so useful in electronics, gives clear guidance on the various processing steps (growth, doping, etching, contact formation, dielectrics etc) and describes how these are integrated in device manufacture.
