Method of forming protective structure for active matrix triode field emission device

A method for manufacturing a protective structure of active matrix triode filed emission device, comprising the steps of:

• forming a silicon active region;
• depositing a gate oxide layer over said silicon active region;
• depositing and patterning a first metal layer over said gate oxide layer;
• doping impurities into portions of said silicon active region to form a source/drain in a first conductive type and simultaneously to form a diode having a terminal in said first conductive type;
• forming an inter layer dielectric (ILD) layer over said first metal layer and forming a plurality of contact holes thereon;
• depositing and patterning a second metal layer;
• forming a passivation layer over said second metal layer and forming a plurality of via holes thereon;
• and
• depositing and patterning a third metal layer to form a gate and a tip structure while connecting said gate to one terminal of said diode and connecting said tip structure said source/drain through said contact holes and said via holes.