Takehiro Hasegawa

A new static memory cell based on reverse base current (RBC) effect of bipolar transistor

A novel SRAM (static random access memory) cell, which consists of a bipolar transistor and an MOS transistor, is proposed. The device, which is based on the reverse base current (RBC) effect, has been fabricated by conventional BiCMOS technology, using double poly-Si. A cell size of 8.58 mu m/sup 2/ has been realized in a 1.0- mu m ground rule. The results indicate that the RBC cell can be applied to very-high-density SRAMs, as large as 16 Mb or beyond.<<ETX>>

A new static memory cell based on the reverse base current effect of bipolar transistors

A SRAM cell that consists of a bipolar transistor and an MOS transistor is proposed. The cells principle of operation is based on the reverse base current (RBC) of a bipolar transistor. It has been fabricated by conventional BiCMOS technology, using double-poly Si. A cell size of 8.58 mu m/sup 2/ is realized in a 1.0- mu m ground rule. The mechanism and characteristics of this cell are discussed. >

Low operation voltage field emitter arrays using low work function materials fabricated by transfer mold technique

Extremely sharp, uniform, and low operation voltage field emitter arrays (FEAs) using low work function materials such as LaB/sub 6/ and TiN have been developed by the Transfer Mold emitter fabrication technique to realize high efficient and high reliable devices for the first time. Because of the sharpening effect on the tips by thermally oxidized SiO/sub 2/ layer of the molds, emitter tip radii are as small as less than 10 nm (2.5-5 nm). The turn-on voltages of LaB/sub 6/ and TiN FEA are 110-130 V lower than that of conventional Mo FEA. That of the gated LaB/sub 6/ FEA is as low as 28 V even without high vacuum baking treatment. Transfer Mold technique provides superior uniformity, sharpness and easiness of selecting low work function materials including diamond which might have negative electron affinity.

An experimental DRAM with a NAND-structured cell

An experimental 256-Mb dynamic random access memory using a NAND-structured cell (NAND DRAM) has been fabricated. The NAND-structured cell has four memory cells connected in series, which reduces the area of isolation between the adjacent cells and also reduces the bit-line contact area. The cell area per bit measures 0.962 mu m/sup 2/, using 0.4- mu m CMOS technology, which is 63% in comparison with the conventional cell. In order to reduce the die size, time division multiplex sense-amplifier (TMS) architecture, in which a sense amplifier is shared by four bit lines, has been newly introduced. The chip area is 464 mm/sup 2/, which is 68% compared with the DRAM using the current cell structure. The data can be accessed by a fast-block-access mode up to 512 bytes as well as a random access mode. Typical 112-ns access time of the first data in a block and 30-ns serial cycle time are achieved. >

Uniform, stable and high integrated field emitter arrays for high performance displays and vacuum microelectronic switching devices

Extremely uniform, stable and high integrated field emitter arrays (FEAs) have been developed by the Transfer Mold emitter fabrication method to realize high performance displays and vacuum microelectronic switching devices for the first time. Transfer Mold FEAs having high emitter density of 7,840,000 tips/cm/sup 2/, containing 9,400,000 emitter tips, one of the highest value reported in the world to date, have demonstrated the lowest value of less than 0.7% of emission fluctuation in the world, and highly uniform, no defect, and flickerless fluorescence. The principle of the vacuum microelectronic switching devices also has been proposed and experimentally verified for the first time by applying high anode voltage of /spl plusmn/1 kV, which will be capable of decreasing the size and the electric power loss of the high voltage electric power converters using conventional semiconductor devices such as Light-triggered thyristors (LTT) and Gate Turn Off thyristors (GTO) to less than 1/100 and 1/10 of them, respectively.