Systems and methods for determination of focus and telecentricity, amelioration of metrology induced effects and application to determination of precision bossung curves
An apparatus and method for the simultaneous determination of focus and source boresighting error for photolithographic steppers and scanners is described. A reticle containing custom arrays of box-in-box test structures specifically designed for performing source or exit pupil division using an aperture plate is exposed onto a resist coated wafer several times. The resulting exposure patterns are measured with a conventional overlay tool. The overlay data is processed with a slope-shift algorithm for the simultaneous determination of both focus and source telecentricity as a function of field position. Additionally, methods for ameliorating metrology induced effects and methods for producing precision Bossung curves are also described. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules, it shall not be used to interpret or to limit the scope or the meaning of the claims.
1. A method for determining focus and source telecentricity for a lithographic projection machine comprising:
providing a reticle containing arrays of box-in-box test structures and aperture plate for exit pupil division, said box-in-box test structures comprising at least one set of large featured alignment attributes and one set of small featured alignment attributes;
exposing at least one array of the box-in-box test structures;
shifting wafer stage to align reference arrays over the box-in-box test structures;
exposing the reference arrays;
measuring the resulting exposure patterns with an overlay tool; and
entering overlay data into an analysis engine, wherein the analysis engine is configured to solve for focus and source telecentricity.
2. The method of claim 1 , wherein the lithographic projection machine is selected from a group consisting of a stepper and a scanner.
3. The method of claim 1 , wherein the exposure includes exposing extra dose structures.
4. The method of claim 1 , wherein the overlay data is corrected for aberrations.
5. The method of claim 1 , wherein the overlay data is corrected for metrology error.
6. The method of claim 1 , wherein the analysis engine is configured to solve for exit pupil telecentricity from the overlay data.
7. The method of claim 1 , wherein the analysis engine is configured to solve for entrance pupil telecentricity from the overlay data.
8. The method of claim 1 , wherein the said reticle is configured for source division.
9. The method of claim 1 , wherein the analysis engine includes lithography simulation.
10. A method for producing an optimized photolithographic chip mask work from a lithographic projection machine and process, the method comprising:
determining a focus result and a source telecentricity result wherein the determining stem comprises:
providing a reticle containing arrays of box-in-box test structures and aperture plate for exit pupil division, said box-in-box test structures comprising at least one set of large featured alignment attributes and one set of small featured alignment attributes;
exposing at least one array of the box-in-box test structures;
shifting wafer stage to align reference arrays over the box-in-box test structures;
exposing the reference arrays;
measuring the resulting exposure patterns with an overlay tool; and
entering overlay data into an analysis engine, wherein the analysis engine is configured to determine focus and source telecentricity;
entering the focus and the source telecentricity results into a machine simulator or controller;
determining optimum operation conditions related to the machine and process to reflect the optimized conditions; and
exposing product wafer(s) using the optimized conditions.
11. A method for producing an optimized photolithographic chip mask work from a lithographic projection machine and process, the method comprising:
determining focus and source telecentricity, wherein the determining step comprises:
providing a reticle containing arrays of box-in-box test structures and aperture plate for exit pupil division, said box-in-box test structures comprising at least one set of large featured alignment attributes and one set of small featured alignment attributes;
exposing at least one array of the box-in-box test structures;
shifting wafer stage to align reference arrays over the box-in-box test structures;
exposing the reference arrays;
measuring the resulting exposure patterns with an overlay tool; and
entering overlay data into an analysis engine, wherein the analysis engine is configured to determining focus and source telecentricity;
entering the focus and source telecentricity results into a machine simulator or controller;
determining precision Bossung curves related to the machine and process; and
exposing product wafer(s) using the precision Bossung curves.