Silicide process for manufacturing a mask ROM

A self-aligned silicide process for forming a mask ROM, comprising:

• forming a gate oxide layer and a first polysilicon layer, respectively, above a silicon substrate;
• using a photolithographic process to define a pattern on the silicon substrate;
• after said using a photolithographic process, implanting ions into the silicon substrate to form a plurality of bit lines on the surface of the silicon substrate, the bit lines extending in a first direction;
• etching the first polysilicon layer to form a plurality of polysilicon strips extending in the first direction;
• forming a second polysilicon layer above the silicon substrate, and covering both the polysilicon strips and the bit lines;
• using photolithographic and etching processes to pattern the second polysilicon layer and the polysilicon strips, and forming a plurality of word lines extending in a second direction that is perpendicular to the first direction;
• forming spacers on respective sidewalls of the word lines;
• forming a metallic layer above the silicon substrate;
• and
• after said forming a metallic layer, using a high temperature and wet etching technique to form a salicide layer above the bit lines and the word lines.