A fourth material: thermally stable organic gap-fill spin-on-polymer enabling new integration concepts [DRAM example]

A fourth material for Si-technology other than silicon, silicon oxide and nitride is introduced in FEOL processing: thermally stable gap-fill organic polymer. It combines the strip-ability of resist with the thermal stability of classic materials, enabling new integration approaches. The feasibility of this material is demonstrated for a new DRAM trench integration scheme. Utilizing a modified version of an organic spin-on-polymer (SiLK* S semiconductor dielectric) with ideal gap fill properties, good planarization and temperature stability up to 450/spl deg/C, a vertical liner stack acting as a "sacrificial collar" was integrated in the top part of the trench by direct deposition of ozone-TEOS on the organic. This resulted in high yielding, fully integrated 256 M DDR DRAMs of 140 nm ground rule with a very low number of failing bits prior to redundancy activation and improved backend retention.