A 4-Mbit DRAM with folded-bit-line adaptive sidewall-isolated capacitor (FASIC) cell

A 5-V 4-Mb word×1-b/1-Mb word×4-b dynamic RAM with a static column model and fast page mode has been built in a 0.8-μm twin-tub CMOS technology with single-metal, two-polycide, and single poly-Si interconnections. It uses an innovative folded-bit-line adaptive sidewall-isolated capacitor (FASIC) cell that measures 10.9 μm/SUP 2/ and requires only a 2-μm trench to obtain a storage capacitor of 50 fF with 10-nm SiO/SUB 2/ equivalent dielectric film. A shared-PMOS sense-amplifier architecture used in this DRAM provides a low power consumption, small C/SUB B/-to-C/SUB S/ capacitance ratio, and accurate reference level for the nonboosted word-line scheme with little area penalty. These concepts have allowed the DRAM to be housed in the industry standard 300-mil dual-in-line package with performances of 90-ns RAS access time and 30-ns column address access time.