FIELD OXIDE FORMING METHOD OF SEMICONDUCTOR

摘要

The field oxide layer is formed by; thermally growing pad oxide and adding nitride; removing nitride over a field region to define active regions; adding side walls on remaining nitride; doping the field region using the spacers as a mask; growing thermal field oxide on the exposed substrate in the field region; removing remaining nitride; and reducing step coverage problem in the field oxide layer by etchback. Size of bird's beak and stress can be reduced at the edges of the field region. A heavil doped channel stop layer is formed only in the middle of the field region so that breakdown and punch through are reduced.