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In this letter, nanoscale p-MOS TFTs with a TiN gate electrode were realized using a novel microwave (MW) dopant-activation technique. We compared both low-temperature MW annealing and rapid thermal annealing. We successfully activated the source/drain region and suppressed the short-channel effects using low-temperature MW annealing. This technique is promising from the viewpoint of realizing high-performance and low-cost upper layer nanoscale transistors required for low-temperature 3-D integrated circuit fabrication

In this study, activation and crystallization in short channel amorphous Si TFTs were demonstrated using a novel microwave annealing (MWA) technique. Both low-temperature MWA and rapid thermal annealing (RTA) were compared to study the dopant activation level. We successfully activated the source/drain region, improved the electronic mobility and suppressed the short-channel effects using low temperature MWA. This can reduce the annealing temperature and processing time below that of solid phase crystallization (SPC). This technique is promising for realizing a high utility rate of AM-LCDs with low cost.The commercial success of active-matrix liquid-crystal displays (AM-LCDs) has attracted much research into the performance improvement of thin-film transistors (TFTs), which function as the pixel switches in AM-LCDs. Various materials have been investigated as candidates for high mobility channels, such as organic semiconductors, 1 amorphous silicon (α-Si), 2 and semi-conducing oxide. 3 Among these candidates, amorphous silicon has attracted much attention because of its wide range of applicability in large area electronics, lower cost and ease of fabrication. 4 Along with finding new materials, it is necessary to develop a low temperature fabrication process capable of producing high performance TFTs (e.g., high carrier mobility and low resistances at source and drain) using glass as a substrate. SPC of α-Si is a method for manufacturing poly-Si films with low cost and excellent uniformity. 5 Although some heatproof glass could accept annealing temperature over 600 • C, 6 it is generally considered to be harsh condition to use glass as the substrate material. In addition, laser annealing, rapid thermal annealing (RTA), and metal-induced crystallization have been also used as annealing techniques for recrystallization and dopant activation in the amorphous or implanted Si layer. While RTA achieves the best results for short durations of processing, the lamp photons are not only heating the Si layer but also stimulate unintended defect formations which cause dopant diffusion. 7 Metal-induced crystallization in the short channels leads to unwanted contaminations of the active regions. 8 Furthermore, MWA were demonstrated to process annealing with lower crystallization temperatures and short dwell times than the SPC process. 9,10 Therefore, the devices with MWA can reduce the impacts of punch-through, DIBL to obtain nano-scaled transistors with good short channel control. 11 In addition, this technique appears to be a promising replacement for RTA for the semiconductor industry. In this study, TFTs on the amorphous-Si films were fabricated using MWA. The MWA process can reduce the crystallization temperature of amorphous Si, lowering the thermal budget of the entire process while enhancing substrate applications. In addition, the shrinkage of the device size may enhance the aperture rate. ExperimentalA 6-in. (100) bulk silicon wafer was used as the starting material. After a 500 nm-thick silicon dioxide (SiO 2 ) laye...