Kensaku Yano

Application of E-beam recrystallization to three-layer image processor fabrication

E-beam recrystallization has been applied to the fabrication of a three-layer processor. The seed structure and the E-beam conditions were successfully optimized so that a large-area SOI as wide as 1 mm was recrystallized without void generation with no damage to underlying devices. The actual SOI area in the device, 850*1100 mu m, was recrystallized with one E-beam scan by aligning its position. The three-layer image processor was capable of visual image sensing with a feature outline extraction in a parallel processing manner. Normal operations of the fundamental functions have been confirmed, demonstrating the feasibility of E-beam recrystallization for three-dimensional IC application. >

A new, laminar flow photo-CVD method for preparing hydrogenated amorphous silicon films

A new, laminar flow type photochemical vapor deposition method has been applied to prepare a-Si:H films. The main feature of this method is introduction of Ar gas as a flow down gas through the lower part of the quartz window into the reaction chamber to keep the window highly transparent. The high deposition rate (150 A/min) of the a-Si:H film has been stably maintained by optimizing the flow rate for each gas into the chamber. Utilizing this new method, we have been able to realize high quality films with low impurity content, high resistivity (>10 11 Ω cm), low dangling bond density (5×10 15 cm -3 ), etc

A Predischarge Doping Method for Hydrogenated Amorphous Silicon Films

A new slight boron doping method, predischarge doping, for a-Si:H films was investigated. Highly resistive borondoped a-Si:H films with 1011~1012 (Ωcm) orders of magnitude have been realized without mobility-lifetime product decrease. The mobility-lifetime product value was nearly the same as that for undoped films.

Frame Transfer CCD Imager with Transparent Electrodes

A frame transfer CCD imager has been fabricated with transparent electrodes as second level electrodes in the image area. The imager with fine-pattern-etched transparent electrodes has 512 V×340 H picture elements. Smaller etching rate for a transparent indium-tin-oxide film, compared with a SiO2 layer, which is a problem in device fabrication, was overcome by employing a new CCD structure. Quantum efficiency of the fabricated imager in visible wave-lengths is 0.5~0.75 and particularly higher for blue light than that of the conventional double poly-Si electrode CCD imager.

Intrinsic type a-SiC:H hole-blocking layer effects on image lag in an amorphous silicon image sensor

Effects of an intrinsic type a-SiC:H hole-blocking layer on a decay lag in an amorphous silicon photo-sensor for an HDTV imager was studied. The decay lag increased proportionally with thickness and gap state density in the intrinsic a-SiC:H layer. It was shown that the decay lag in the i-type a-SiC:H layer was caused by thermal release of carriers from gap states in this layer. An extremely low, 0.66%, decay lag has been realized by optimizing the i-type a-SiC:H hole-blocking layer. The optimization for the layer was due to its thickness and its carbon content.

A new, pre-discharge boron doping method for amorphous silicon photoconversion layer in HDTV image sensor

A novel predischarge boron doping method for amorphous silicon (a-Si) has been applied to a high-definition-television (HDTV) solid-state CCD imaging device. A lightly boron doped a-Si photoconversion layer achieved by this method has high resistivity (>10/sup 11/ Omega cm) and a large electron-mobility-lifetime product ( mu tau =3*10/sup -7/ cm/sup 2//V). Using this a-Si layer, a high-resolution, high-resistivity image sensor has been realized without any pixel separation structure in its photoconversion layer.<<ETX>>