Patent ID: 6268267
Filing Date: 2001-07-31
Classification: H01L

Abstract:
A method for forming a Localized Oxidation Isolation (LOCOS) region, comprising the steps of:providing a silicon substrate;depositing a layer of silicon-oxynitride-oxide (SXO) over the surface of said substrate by exposing the surface of said substrate is to a mixture of SiH.sub.4, N.sub.2 O and NH.sub.3 using either Low Pressure CVD (LPCVD) or Plasma Enhanced CVD (PECVD) techniques, thereby creating an initial layer of SiON on the surface of said substrate said initial layer is to be between about 75 and 200 Angstrom thick, by then decreasing the nitrogen concentration while increasing the oxygen concentration in said mixture of SiH.sub.4, N.sub.2 O and NH.sub.3 by adjusting the mixture of N.sub.2 O and NH.sub.3 by decreasing the concentration of NH.sub.3 while increasing the concentration of N.sub.2 O in said mixture of SiH.sub.4 +N.sub.2 O+NH.sub.3 thereby creating a modified mixture of SiH.sub.4, N.sub.2 O and NH.sub.3 said increasing and decreasing to continue for a deposition of the layer of SXO of between about 50 and 100 Angstrom thick, by then eliminating the NH.sub.3 flow from said modified mixture of SiH.sub.4 +N.sub.2 O+NH.sub.3 and completing said deposition of said layer of silicon-oxynitride-oxide (SXO) to an overall thickness of between about 200 and 500 Angstrom;depositing a layer of silicon nitride over said layer of SXO;defining active regions for said silicon substrate thereby by inclusion defining the LOCOS regions for said silicon substrate; andperforming wet oxidation of said LOCOS regions.