AN EXPERIMENTAL HIGH-DENSITY DRAM CELL WITH A BUILT-IN GAIN STAGE

A new high-density DRAM cell concept is proposed and experimentally demonstrated. This cell, composed of two transistors and one capacitor, generates a large bit line signal with a small cell capacitance during the read cycle. Since it does not need a large storage capacitance and one transistor is stacked on the top of the other transistor, the cell size is small and can be easily scaled down for future generations of memory devices. The unit cell size fabricated using a 4 M SRAM process without any process modification is 1.8 mum x 2.85 mum. The proposed cell can be adopted to store multi-bit information. The fabricated prototype cell shows a resolution of about 3.5 bit.