A self-aligned 1-µm-channel CMOS technology with retrograde n-well and thin epitaxy

A six-mask 1-µm CMOS process with many self-aligned features is described. It uses a thin p-type epitaxial layer on a p⁺substrate and a retrograde n-well. Self-aligned TiSi2is formed on n⁺and p⁺diffusions to reduce the sheet resistance and to make butted source contacts. It is shown that n⁺poly-gated p-channel devices can be properly designed with low threshold magnitudes and good turn-off characteristics. With a 5-V supply, the minimum gate delay of unloaded CMOS ring oscillators is 150 ps/stage. Furthermore, it is demonstrated that this CMOS technology is latchup free since the holding voltage for latchup is higher than 5 V.