Process for suppressing boron penetration in BF.sub.2 .sup.+ -implanted P.sup.+ -poly-Si gate using inductively-coupled nitrogen plasma

A process for suppressing boron penetration through a BF.sub.2 + implanted p+ type polycrystalline Si gate region using an inductively coupled nitrogen plasma, said process comprising

• (a) growing a gate oxide layer on a silicon wafer substrate by steps of washing said silicon wafer, placing said substrate in a high temperature furnace, and introducing oxygen at temperatures of 900.degree.-1000.degree. C. to grow said oxide layer of 50-120 .ANG. thickness;
• (b) carrying out an inductively coupled plasma treatment of said silicon wafer in nitrogen at a power of 100-300 W for 1-30 minutes to form a nitrided layer on said oxide layer providing an energy barrier substantially impenetrable by boron ions;
• (c) forming at least one layer of polycrystalline silicon of approximately 1000-3000 .ANG. thickness on said nitrided layer and said oxide layer;
• (d) implanting BF.sub.2 + ions at an energy of 30-70 keV in an amount of 1.times.10.sup.15 to 1.times.10.sup.16 atoms/cm.sup.2 into said at least one layer of polycrystalline silicon to form a p+ type gate region;
• (e) washing said silicon wafer again;
• and
• (f) again placing said silicon wafer into said high temperature furnace, introducing one of nitrogen or oxygen at 800.degree. to 1000.degree. C., and annealing for 10-60 minutes.