Shallow trench isolation with conductive hard mask for in-line moat/trench width electrical measurements
AssigneeTexas Instruments Incorporated
InventorsMahalingam Nandakumar, Seetharaman Sridhar
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Abstract
A method for forming STI that allows for in-situ moat/trench width electrical measurement is disclosed herein. A conductive layer (18) is used in the hard mask (20) for trench etch. After the hard mask (20) is formed and the trench (12) is etched, the resistance of the conductive layer (18) is measured over a predefined length. Since the length is known, the average width of the hard mask (20)/moat (11) can be determined. Once the width of the moat (11) is known, the width of the trench (12) can easily be determined by subtracting the width of the moat (12) from the pitch, which is a known factor.
Claims18
A method for forming shallow trench isolation comprising:
- forming a conductive layer over a semiconductor;
- forming a trench mask using said conductive layer, said trench mask having trench openings;
- connecting probe pads to two ends of a portion of said conductive layer after said step of forming said trench mask;
- measuring the electrical resistance of said portion of said conductive layer;
- determining a width of said trench openings using the measured electrical resistance;
- etching a trench using said trench mask;
- and
- filling said trench.
A method of forming a test structure for determining trench width, comprising the steps of:
- forming a conductive layer over a semiconductor, said conductive layer having a plurality of parallel strips connected to each other;
- forming a trench mask using said conductive layer, said trench mask having trench openings;
- forming probe pads at two ends of said conductive layer after said step of forming said trench mask;
- measuring the electrical resistance of said conductive layer after said step of forming said trench mask;
- determining an average width of said plurality of parallel strips from said electrical resistance;
- determining a width of said trench openings using said average width;
- etching a trench using said trench mask;
- and
- filling said trench.
Dependencies are inferred from the claim text.