Isolation formation process with active area protection

A protected active region formed on a surface of a semiconductor substrate, for future device formation surrounded by an isolation region, made by the process comprising the steps of:

• forming a protective material over the protected region of the surface of the semiconductor substrate;
• selectively forming a layer of thermal silicon nitride in the exposed portions of the semiconductor substrate immediately surrounding the protected region;
• forming at least one masking cover over the protected region and the surrounding thermal silicon nitride layer;
• patterning the masking cover and the thermal silicon nitride layer to reveal portions of the semiconductor substrate;
• forming an isolation region in the semiconductor substrate revealed in the previous step;
• and
• removing the masking cover, thermal silicon nitride layer and protective material to expose the protected region.

A protected active region formed on a surface of a semiconductor substrate, for future device formation, surrounded by an isolation region, made by the process comprising the steps of:

• forming a uniform layer of protective material over the surface of the semiconductor substrate;
• forming a uniform layer of first masking material over the uniform layer of protective material;
• patterning the layers of first masking material and the layer of protective material to form an island surrounded by an exposed semiconductor substrate surface;
• selectively forming a layer of thermal silicon nitride on the exposed regions of semiconductor substrate surface;
• forming a uniform layer of second masking material over the island and the layer of thermal silicon nitride;
• patterning the uniform layer of second masking material and the layer of thermal silicon nitride to form a sidewall of second masking material around the island, the sidewall having a ring of thermal silicon nitride beneath to form a ringed island surrounded by a contracted exposed region of semiconductor substrate surface;
• forming an isolation region in the contracted exposed regions of semiconductor substrate surface;
• and
• removing the first and second masking layers, ring of thermal silicon nitride and protective material to expose the protected region.

A protected active region formed on a surface of a monocrystalline silicon substrate, for future device formation, surrounded by an isolation region, made by the process comprising the steps of:

• forming a uniform layer of silicon dioxide over the surface of the silicon substrate;
• forming a first uniform layer of silicon nitride over the uniform layer of silicon dioxide;
• patterning the layers of silicon nitride and the layer of silicon dioxide to form an island surrounded by an exposed region of silicon substrate surface;
• selectively forming a layer of thermal silicon nitride on the exposed regions of silicon substrate surface;
• forming a second uniform layer of silicon nitride over the island and the layer of thermal silicon nitride;
• patterning the second uniform layer of silicon nitride and the layer of thermal silicon nitride to form a sidewall of silicon nitride around the island, the sidewall having a ring of thermal silicon nitride beneath to form a ringed island surrounded by a contracted exposed region of silicon substrate surface;
• forming a silicon dioxide isolation region in the contracted exposed region of silicon substrate surface;
• and
• removing the first and second layers of silicon nitride, ring of thermal silicon nitride and protective layer of silicon dioxide to expose the protected region.