Title :
A cell transistor scalable DRAM array architecture
Author :
Takashima, Daisaburo ; Nakano, Hiroaki
Author_Institution :
Memory LSI Res. & Dev. Center, Toshiba Corp., Yokohama, Japan
fDate :
5/1/2002 12:00:00 AM
Abstract :
Presents a new DRAM array architecture for scaled DRAMs. This scheme suppresses the stress bias for memory cell transistors and enables memory cell transistor scaling. In this scheme, the data "1" and data "0" are written to the memory cell in different timing. First, for all selected cells, data "1" is written by boosting wordline (WL) voltage. Second, after pulling down WL voltage to a lowered value, data "0" is written only for data "0" cells. This scheme reduces stress bias for the cell transistor to half of that of the conventional operation. The time loss for data "1" write is eliminated by parallel processing of data "1" write and sense amplifier activation. This scheme realizes fast cycle time of 50 ns. By adopting the proposed scheme, the gate-oxide thickness of the cell transistor is reduced from 5.5 to 3 nm, and the memory cell size is reduced to 87% in 0.13-μm DRAM generation. Moreover, the application of the oxide-stress relaxation technique to all row-path circuits as well as the proposed scheme enables high-performance DRAM with only a thin gate-oxide transistor
Keywords :
DRAM chips; cellular arrays; integrated circuit reliability; memory architecture; parallel architectures; stress relaxation; 0.13 micron; 3 nm; 50 ns; DRAM array architecture; cell transistor scalable array; cycle time; gate-oxide thickness; memory cell transistors; oxide-stress relaxation technique; parallel processing; reliability; row-path circuits; sense amplifier activation; stress bias; thin gate-oxide transistor; time loss; wordline voltage; Degradation; Large scale integration; Logic; Random access memory; Research and development; Scalability; Stress; Threshold voltage; Timing; Transistors;
Journal_Title :
Solid-State Circuits, IEEE Journal of