Method for calibrating a metrology tool

1. A method for calibrating a metrology tool, comprising:

providing a substrate including at least one calibration site, the calibration site including a pattern of cells;

providing at least one feature in each of the cells, the at least one feature disposed in a surface of the substrate;

measuring the feature using a phase metrology tool to provide a measured phase shift;

comparing the measured phase shift with an initial phase shift associated with the feature; and

adjusting the phase metrology tool if the measured phase shift does not match the initial phase shift.

2. The method of claim 1 , further comprising:

measuring the feature using a step height metrology tool to provide a measured depth;

comparing the measured depth with an initial depth associated with the feature; and

adjusting the step height metrology tool if the measured depth does not match the initial depth.

3. The method of claim 1 , further comprising the phase metrology tool including an exposure wavelength between approximately 100 nanometers and approximately 400 nanometers.

4. The method of claim 3 , further comprising the feature including a depth operable to produce a phase shift of approximately 180 degrees at the exposure wavelength.

5. The method of claim 1 , further comprising providing a plurality of calibration sites formed on the substrate, a first calibration site located in a center of the substrate and a second calibration site located proximate an edge of the substrate.

6. The standard of claim 1 , further comprising forming the feature in the substrate using a wet etch process.