A deep-trenched capacitor technology for 4 mega bit dynamic RAM

A deep-trenched capacitor technology is one of key processes for realizing 4Mb DRAM(1). Major subjects in this technology are to form a precisely controlled shallow diffusion layer at vertical side walls and to grow high reliable thin gate oxide on the trenched Si surface. In this paper, arsenic doping from As doped SiO2(AsSG) film into the vertical side walls and the rounding oxidation technique in O2ambient including a few percent H2O, have been introduced. These techniques enable us to utilize the high-reliability trenched capacitors featuring large charge storage capability as well as low leakage current for 4Mb DRAM´s.