A quadruply self-aligned MOS (QSA MOS) a new short channel high speed high density MOSFET for VLSI

A new device named Quadruply Self-Aligned (QSA) MOS is proposed to overcome speed and density limit of conventional scaled down MOS VLSI circuits. This device includes four mutually self-aligned areas: poly Si gate area, shallow source drain area to eliminate short channel effect, deep junction area with high conductance and specific contact area to afford efficient metallic interconnection, thus achieving high speed and high density. Fabrication processes involve undercutting of poly Si gate, anisotropic ion etching of SiO2and source drain ion implantation. Experimental results of the device and feasibility of MOS RAM with a density of 1 Mbit/6 × 4 mm²storage area are described.