Method for high temperature semiconductor processing

In processing a monocrystalline silicon substrate, the steps comprising:

• A. oxidizing a surface portion of said substrate in an oxidizing atmosphere at a first elevated temperature in the range of about 900.degree.C to about 1200.degree.C;
• B. transferring the wafer of Step A at said first elevated temperature to a heated second atmosphere of oxygen and an inert diluent gas and thermally stabilizing said substrate therein at a second temperature in the range of about 800.degree. to about 900.degree.C;
• C. establishing a third processing atmosphere by introducing a conductivity determining impurity into said second atmosphere and forming therein a said impurity doped oxide over said surface portion of said substrate at said second temperature;
• D. reforming said third atmosphere to said second atmosphere of oxygen and a diluent inert gas at said second temperature with said substrate disposed therein,
• E. heating said substrate in said reformed second atmosphere to a third temperature in the range of about 900.degree. to about 1200.degree.C;
• E. annealing said substrate at said third temperature in said reformed second atmosphere to remove fast surface states in said substrate from said doped oxide into said substrate;
• G. removing said substrate from said reformed second atmosphere for cooling to ambient temperatures;
• and
• H. cooling the process tube in said reformed second atmosphere from said third temperature to a fourth temperature in the range from about 800.degree. to about 900.degree.C.