Method for preparing nitrogen surface treated fluorine doped silicon

Abstract

A process of preparing a moisture-resistant fluorine containing SiO.sub.x film includes steps of supplying reactant gases containing silicon, oxygen and fluorine into a process chamber and generating plasma in the process chamber, supporting a substrate on a substrate support in the process chamber, depositing a fluorine-containing SiO.sub.x film on the substrate by contacting the substrate with the plasma while maintaining temperature of the film above 300.degree. C., and nitriding an exposed surface of the film with a high density plasma. The silicon and fluorine reactants can be supplied by separate gases such as SiH.sub.4 and SiF.sub.4 or as a single SiF.sub.4 gas and the oxygen reactant can be supplied by a pure oxygen gas. The SiH.sub.4 and SiF.sub.4 can be supplied in a ratio of SiH.sub.4 /(SiH.sub.4 +SiF.sub.4) of no greater than 0.5. The process can provide a film with a fluorine content of 2 to 12 atomic percent and argon can be included in the plasma to assist in gap filling. The plasma can be a high density plasma produced in an ECR, TCP.TM. or ICP reactor and the substrate can be a silicon wafer including one or more metal layers over which the fluorine-containing SiO.sub.x film is deposited. The substrate support can include a gas passage which supplies a temperature control gas into a space between opposed surfaces of the substrate and the substrate support for maintaining the substrate at a desired temperature. The nitriding step can be carried out in less than 1 minute without applying an rf bias to the substrate. The nitriding gas can be N.sub.2, N.sub.2 O and/or NH.sub.3, the nitrogen ion energy can be 20 to 50 eV, the nitrogen flux can be at least 1 mA/cm.sup.2 and the nitrogen gas flow rate can be at least 50 sccm.