Focus blur measurement and control method

1. A method for optimizing imaging and process parameter settings in a lithographic pattern imaging and processing system is disclosed, the method comprising:

correlating the dimensions of a first set of at least one control pattern printed in a lithographic resist layer, measured at three or more locations on or within the pattern which correspond to differing dose, defocus and blur sensitivity, the locations of high defocus sensitivity on or within a pattern corresponding to different heights on the profile in the resist layer resulting from the image of a low density pattern and comprising isolated features for which pitch to an adjacent feature is significantly greater than twice the width of the smallest feature dimension and the location of low defocus sensitivity corresponding to a single height on the profile in the resist layer resulting from the image of a high density pattern and comprising nested features for which pitch to an adjacent feature is not significantly greater than twice the width of the smallest feature dimension, the dimensions of the first set of at least one control pattern being measured at different blur condition of the pattern imaging system varied by changing bandwidth of illumination or tilt of an image plane in the lithographic pattern imaging and processing system;

measuring the dimensions on subsequent sets of control patterns, printed in a lithographic resist layer, simultaneously at three or more locations on or within each pattern, of which a minimum of three locations match those measured in the first set; and

determining the effective dose, defocus and blur values associated with forming the subsequent sets of control patterns by comparing the dimensions at the matching locations with the correlated dependencies.

2. A method of determining blur, focus and exposure dose error in lithographic imaging comprising:

providing nested and isolated features in a design to be lithographically patterned on a substrate;

lithographically patterning the nested and isolated features on a substrate at different focus settings for different blur conditions, the different blur conditions comprise different spectral widths of radiation used for the lithographic patterning or different tilts of the image plane, dimension of the isolated feature being sensitive to, and dimension of the nested feature being relatively insensitive to, the different focus setting for the different blur conditions;

measuring dimensions of the nested feature at the different focus settings for the different blur conditions;

simultaneously with the measuring of the nested feature, measuring dimensions of the isolated feature at the different focus setting for the different radiation blur conditions;

determining contribution of blur error based on shifts in the dimension of the isolated feature at the different focus setting for the different blur conditions with respect to dimensions of the nested feature; and

determining focus and exposure dose error based on any shifts in the dimension of the isolated feature at the different focus setting for the different blur conditions with respect to dimensions of the nested feature.

3. The method of claim 2 wherein the different blur conditions comprise different spectral widths of radiation used for the lithographic patterning.

4. The method of claim 2 wherein the different blur conditions comprise different tilts of the image plane.