SOI-DRAM circuit technologies for low power high speed multigigascale memories

This paper describes a silicon on insulator (SOI) DRAM which has a body bias controlling technique for high-speed circuit operation and a new type of redundancy for low standby power operation, aimed at high yield. The body bias controlling technique contributes to super-body synchronous sensing and body-bias controlled logic. The super-body synchronous sensing achieves 3.0 ns faster sensing than body synchronous sensing and the body-bias controlled logic realizes 8.0 ns faster peripheral logic operation compared with a conventional logic scheme, at 1.5 V in a 4 Gb-level SOI DRAM. The body-bias controlled logic also realizes a body-bias change current reduction of 1/20, compared with a bulk well-structure. A new type of redundancy that overcomes the standby current failure resulting from a wordline-bitline short is also discussed in respect of yield and area penalty     

A 1.0-V 230-MHz column access embedded DRAM for portable MPEGapplications

This paper describes a 32-Mb embedded DRAM macro fabricated using 0.13-μm triple-well 4-level Cu embedded DRAM technology, which is suitable for portable equipment of MPEG applications. This macro can operate 230-MHz random column access even at 1.0-V power supply condition. The peak power consumption is suppressed to 198 mW in burst operation. The power-down standby mode, which suppresses the leakage current consumption of peripheral circuitry, is also prepared for portable equipment. With the collaboration of array circuit design and the fine Cu metallization technology, macro size of 18.9 mm² and cell efficiency of 51.3% are realized even with dual interface and triple test functions implemented     

An experimental 256-Mb DRAM with boosted sense-ground scheme

In developing the 256-Mb DRAM, the data retention characteristics must inevitably be improved. In order for DRAM's to remain the semiconductor device with the largest production volume in the 256-Mb era, we must develop a cost effective device with a small chip size and a large process tolerance. In this paper, we propose the BSG (boosted sense-ground) scheme for data retention and FOGOS (folded global and open segment bit-line) structure for chip size reduction. We have fabricated an experimental 256-Mb DRAM with these technologies and obtained a chip size of 304 mm² and a performance of 34 ns access time     

A 5.3-GB/s embedded SDRAM core with slight-boost scheme

This paper describes a slight-boost scheme to improve a transistor performance in system large-scale integrated circuits, which integrate logic circuits and 1-Tr/1-C DRAMs. In this scheme, an embedded SDRAM core has been developed for graphic and multimedia applications. Its maximum operating frequency is 166 MHz, with a peak data rate of 5.3 GB/s. As well, a fast row-address access time of 22 ns has been achieved. The SDRAM core has been fabricated by means of a 0.3-μm quad-polysilicon, triple metal, triple-well CMOS process. This SDRAM core has a block write function, enhanced by a multiselect block write scheme, and a synchronous direct memory-access test circuit has been implemented to reduce the number of test pads     

A well-synchronized sensing/equalizing method for sub-1.0-Voperating advanced DRAMs

Proposes an advanced DRAM array driving technique which can achieve low-voltage operation, a well-synchronized sensing and equalizing method. This method sets the DRAM array free from the body effect, achieves a small influence of the short channel effect, and reduces the leakage current. The sense and restore amplifier and equalizer can operate rapidly under a low-voltage operating condition such as 1.0 V V_CC. Therefore, one can make determining the V _th easy for the satisfaction of the high-speed, the low-power dissipation, and a simple device structure. The well-synchronized sensing and equalizing method is applicable to low-voltage operating DRAMs with capacity of 256 Mbits and more     

0.13-μm 32-Mb/64-Mb embedded DRAM core with high efficientredundancy and enhanced testability

This paper describes the 32-Mb and the 64-Mb embedded DRAM core with high efficient redundancy, which is fabricated using 0.13-μm triple-well 4-level Cu embedded DRAM technology. Core size of 18.9 mm ² and cell efficiency of 51.3% for the 32-Mb capacity, and core size of 33.4 mm² and cell efficiency of 58.1% for the 64-Mb capacity are realized. This core can achieve 230-MHz burst access at 1.0-V power-supply condition by adopting a new data bus architecture: merged shift column redundancy. We implemented four test functions to improve the testability of the embedded DRAM core. It realizes the DRAM core test in a logic test environment     

Low voltage circuit design techniques for battery-operated and/orgiga-scale DRAMs

This paper describes a charge-transferred well (CTW) sensing method for high-speed array circuit operation and a level-controllable local power line (LCL) structure for high-speed/low-power operation of peripheral logic circuits, aimed at low voltage operating and/or giga-scale DRAMs. The CTW method achieves 19% faster sensing and the LCL structure realizes 42% faster peripheral logic operation than the conventional scheme, at 1.2 V in 15 Mb-level devices. The LCL structure realizes a subthreshold leakage current reduction of three or four orders of magnitude in sleep mode, compared with a conventional hierarchical power line structure. A negative-voltage word line technique that overcomes the refresh degradation resulting from reduced storage charge (Q_s) at low voltage operation for improved reliability is also discussed. An experimental 1.2 V 16 Mb DRAM with a RAS access time of 49 ns has been successfully developed using these technologies and a 0.4-μm CMOS process. The chip size is 7.9×16.7 mm² and cell size is 1.35×2.8 μm²