Method of performing metrology on a microfabrication pattern

A non-transitory computer-readable media storing instructions that, when executed by a computing device, cause the computing device to perform functions comprising:

• transmitting control parameters to a scanning electron microscope;
• generating, by the scanning electron microscope and according to the control parameters, a first set of frames of a first region of a microfabrication pattern, a second set of frames of a second region of the microfabrication pattern, and a third set of frames of a third region of the microfabrication pattern, wherein a number of frames of the first set, the second set and the third set are different;
• estimating, using the first set, the second set, and the third set, first feature data corresponding to the first set, second feature data corresponding to the second set, and third feature data corresponding to the third set, wherein the first feature data, the second feature data, and the third feature data represent edge positions, linewidths, or centerline positions of features of the microfabrication pattern;
• computing a first preliminary estimate, a second preliminary estimate, and a third preliminary estimate of a roughness parameter from the first feature data, the second feature data, and the third feature data, wherein the roughness parameter is indicative of a line edge roughness, a linewidth roughness, or a pattern placement roughness of the features of the microfabrication pattern;
• fitting a model equation to the first preliminary estimate, the second preliminary estimate, and the third preliminary estimate using a model parameter that is dependent on the number of frames of the first set, the second set, or the third set, the model equation relating the model parameter to the roughness parameter, wherein the model parameter is an average signal-to-noise ratio for the first set, the second set, or the third set;
• and
• computing a final estimate of the roughness parameter using the model equation.

A computing device comprising:

• a processor;
• and
• a computer readable medium storing instructions that, when executed by the processor, cause the computing device to perform functions comprising:
• transmitting control parameters to a scanning electron microscope;
• generating, by the scanning electron microscope and according to the control parameters, a first set of frames of a first region of a microfabrication pattern, a second set of frames of a second region of the microfabrication pattern, and a third set of frames of a third region of the microfabrication pattern, wherein a number of frames of the first set, the second set and the third set are different;
• estimating, using the first set, the second set, and the third set, first feature data corresponding to the first set, second feature data corresponding to the second set, and third feature data corresponding to the third set, wherein the first feature data, the second feature data, and the third feature data represent edge positions, linewidths, or centerline positions of features of the microfabrication pattern;
• computing a first preliminary estimate, a second preliminary estimate, and a third preliminary estimate of a roughness parameter from the first feature data, the second feature data, and the third feature data, wherein the roughness parameter is indicative of a line edge roughness, a linewidth roughness, or a pattern placement roughness of the features of the microfabrication pattern;
• fitting a model equation to the first preliminary estimate, the second preliminary estimate, and the third preliminary estimate using a model parameter that is dependent on the number of frames of the first set, the second set, or the third set, the model equation relating the model parameter to the roughness parameter, wherein the model parameter is an average signal-to-noise ratio for the first set, the second set, or the third set;
• and
• computing a final estimate of the roughness parameter using the model equation.