Shuhei Tsuchimoto

Design and implementation of a 3D-LSI image sensing processor

A four-story structured image sensing processor implemented with three-dimensional LSI (3D-LSI) technology and integrating 5040 pixel photodiodes and 0.22 million transistors on a 14.3-mm/sup 2/ single die is described. The implemented chip allows a large degree of data parallelism in image computations where the image sensor unit operates without synchronous clocks. The chip, which is a second prototype, is able to sense 12 characters at the same time, and can recognize 64 different characters in upper and lower case, Arabic numerals, and some symbols, each consisting of a 10*14 matrix. The chip is made of a large number of simple processing elements working in parallel, which speeds up computation. The time needed to identify a sensed image as a memorized character is about 3 mu s. Successful measurements of the principal functions verify the usefulness of the chip. >

Formation of Sources/Drains Using Self-Activation Technique on Polysilicon Thin Film Transistors

Source/drain formation by ion doping using self-activation technique without thermal anneal on polysilicon thin film transistors (TFTs) have been investigated. Phosphorus ions and protons were simultaneously implanted into polysilicon films. At total ion doses over 8×1015 ions/cm2, resistivities of self-activated films have been found equal to those of the ones annealed after the implantation. This self-activation technique enabled us to fabricate self-aligned TFTs having low-resistance Al gates and, at the same time, to hydrogenate active layers. With the case of self-activation technique, field-effect mobilities as high as 58 and 49 cm2/(Vs) were achieved in n-channel and p-channel TFTs, respectively, fabricated on glass substrates.

Crystallization Phenomenon Induced by Proton Beam Irradiation using Large Area Ion Implantation for Polycrystalline Silicon Thin Film Transistors

Crystallization induced by proton beam irradiation using large area ion implantation at low temperature (less than 600°C) have been investigated. Phosphine gas containing hydrogen of more than 95% is discharged by RF power of 100W. Both phosphorus ions and protons are accelerated by a potential of 100kV and implanted into polycrystalline silicon (poly-Si) layers. At a range of beyond 2×10 15 ions/cm 2 P 1 ions dose, amorphous phase is primarily formed and then changes into polycrystals again and its grain sizes grow up to 50nm in average diameter. The crystallization is found to occur simultaneously with phosphorus doping and to depend on the amount of the irradiated protons. This technique enables us to eliminate the activation annealing process for implanted dopant.

Fabrication of Self-Aligned Aluminum Gate Polysilicon Thin-Film Transistors Using Low-Temperature Crystallization Process

The performance of scanning driver circuits fabricated with self-aligned aluminum gate polysilicon thin-film transistors (TFTs) is demonstrated. After the gate electrode patterning, the fabrication process temperature is kept below 400 o C to enable the use of aluminum gate electrodes. The low-temperature crystallization phenomenon, which occurs when protons are implanted simultaneously with boron or phosphorus dopants, is employed to eliminate the 600 o C activation-annealing process. A maximum clock frequency of about 2.0 MHz is achieved when the driver operating voltage is 24 V and the TFT channel length is 12 μm

Four-story Structured Character Recognition Sensor Image with 3D Integration

This paper describes the design and implementation of a four-story structured character recognition system with three-dimensional (3D) integration. This device is capable of sensing the image of 12 characters at the same time and also recognizing 64 kinds of characters. The efficiency of the device has been verified.

Anisotropy and Hysteresis Behavior of Galvanomagnetic Effect in Super Magneto-Resistor

The hysteresis behavior, fluctuation and their anisotropy of galvanomagnetic effect in novel magnetic sensor using bulk and film samples of ceramic superconductor Y-Ba-Cu-O have been measured. For the bulk element, the hysteresis was observed and its property was independent of the direction of magnetic field. For the film element, when the magnetic field direction was perpendicular to the element surface, the hysteresis was observed in a way similar to the bulk element, but when the magnetic field direction was parallel to the element surface, the hysteresis was eliminated to zero and fluctuation of output voltage was greatly reduced. These properties can be explained by considering the dynamics of magnetic flux trapping in the element.

Design and implementation of a 3D-LSI character recognition image sensor

A four-story structured character recognition image sensor has been implemented with three-dimensional LSI technology, integrating 55-thousand diodes and 0.22-million transistors on a 14.3-mm square single die. Three-dimensional LSIs will achieve very high performance by exploiting the structural parallelism by way of the inherent parallelism of the algorithm. The chip, which is the second-step prototype of the Intelligent Image Sensor, is able to sense 12 characters of an image at the same time and recognize 64 kinds of characters containing the alphabet in upper and lower case, Arabic numerals, and some symbols, each consisting of a 10*14 bit matrix. The present chip allows a 20 times larger degree of data parallelism in image computation and a considerably higher speed of recognition in data matching compared with a previous chip. The efficiency of the chip has been verified.<<ETX>>

Application of optical fiber array to contact-type image sensors

In order to develop small-size, high-fidelity input for reading letters and images, the authors studied the use of an optical fiber array to obtain compact contact-type image sensors. The optical system exhibited a modulation transfer function of 50% at 8 lp/mm, about the same depth of field as that of a rod lens array; a uniformity of less than +or-4.5%; and a transmittance of about 25%. The illuminance achieved by the system is about four times as large as that of the conventional one, and the resolution characteristics of the system are excellent as well. A 2048-bit, 70-bit/mm linear charge-coupled device or a 1728-bit, 8-bit/mm a-Si:H thin-film linear photodiode array is used as the photodetector of the image sensor. Letters (e.g. 8 point size) and images of documents were read and reproduced by a thermal printer successfully.<<ETX>>

Improvement in sensitivity of novel magnetic sensor using Y-Ba-Cu-O ceramic superconductor film

The authors report an improvement in the sensitivity of a magnetic sensor made of high-T/sub c/ ceramic superconductor. The sensitivity is discussed in connection with the noise measurement of a film element. It is believed that a high sensitivity comparable to that of a high-T/sub c/ SQUID (superconducting quantum interference device) utilizing ceramic materials can be obtained with the present magnetoresistive superconductive element. The magnetic field dependence of the electric resistance of the element at 77 K is shown. The sensitivity as a function of the current is compared for various elements. It is found that the sensitivity of this element is about 100000 times higher than that of a bulk element reported last year. The magnetoresistance at low magnetic field is attributed to the weak couplings between superconductive grains in a ceramic semiconductor. Thus the ceramic superconductor is considered to be a multiconnected Josephson network. The noise is mainly due to the presence of trapped magnetic flux. The reduction of the noise for parallel magnetic field implies the elimination of the trapped flux. Noise measurements are also reported.<<ETX>>