Method for fabricating a semiconductor integrated circuit with a litho-etch, litho-etch process for etching trenches

A method for fabricating a semiconductor integrated circuit comprising:

• providing a semiconductor substrate with an overlying process layer;
• determining a trench pattern to be etched into the process layer, the trench pattern including an isolated trench;
• forming a lithographic mask implementing the trench pattern and further including first and second density balancer patterns symmetrically positioned with respect to the isolated trench;
• applying a resist layer overlying the process layer;
• patterning the resist layer with the lithographic mask;
• and
• etching the process layer using the patterned resist layer as an etch mask.

A method for fabricating a semiconductor integrated circuit comprising:

• providing a process layer overlying a semiconductor substrate;
• determining a trench pattern to be etched into the process layer as required for the semiconductor integrated circuit being fabricated;
• decomposing the trench pattern into a first pattern of lithographically printable features and a second pattern of lithographically unprintable features including an isolated trench;
• converting the lithographically unprintable features to lithographically printable features by adding density balancer patterns to the second pattern in spaced apart symmetric relationship to the isolated trench to form a converted second pattern;
• and
• etching the first pattern and the converted second pattern into the process layer.