A New Sealed Poly Buffer Locos Isolation Scheme

A LOCOS isolation technique for devices with deep submicron dimensions should combine a small lateral encroachment (bird´s beak) with good gate oxide quality and low junction leakage currents. In this paper we present a new isolation scheme, capable of defining deep submicron features: the Sealed Poly Buffer LOCOS process (Sealed PBLOCOS). We will show that there is only a minor dependence of birds´ beaks on mask geometry. An electrical characterisation of the Sealed PBLOCOS scheme revealed low junction leakage and a gate oxide quality comparable to conventional LOCOS isolation schemes.