A Novel 1T-DRAM Fabricated with 22 nm FD-SOI Technology

A novel single-transistor dynamic random access memory (1T-DRAM) named IS-DRAM (in-situ sensing DRAM) which combines non-destructive reading with compact footprint is experimentally demonstrated with advanced 22nm fully depleted silicon-on-insulator (FD-SOI) technology. Unlike conventional 1T-DRAM using floating-body effect in SOI, the IS-DRAM stores charge in the substrate beneath the buried oxide (BOX). The stored charge modulates the drain current of the top Si transistor through interface coupling effect, and thus the state of the memory is “in-situ” read out. A buried accessing diode is formed in the substrate in order to write and erase the stored charge. Excellent writing time and retention reaching 10ns and 94ms at 85°C respectively have been measured in IS-DRAM with 26 nm gate length.