Metrology mark structure and method of determining metrology mark structure

A computer program product comprising a non-transitory computer readable medium having instructions therein, the instructions, when executed by a computer system, configured to cause the computer system to at least:

• a) obtain an initial version of a characteristic function of an initial version of a metrology mark disposed within a layer stack for use in a lithography process, the initial version of the metrology mark comprising a plurality of mark segments, at least one of the mark segments comprising a plurality of subsegments, wherein the characteristic function comprises:
• a change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the layer stack, the reflected beam being a beam reflected from the metrology mark and passing through the layer stack, or
• a change in angular reflectance of the reflected beam as a function of a change in thickness of the stack;
• b) perturb one or more variables of the plurality of subsegments, wherein the one or more variables comprise pitch, duty cycle, and/or line width of the plurality of subsegments;
• c) perturb a thickness of one or more layers within the layer stack;
• d) update the characteristic function based upon the perturbations of b) and c);
• e) iteratively perform b), c) and d) until a further version of the characteristic function is determined to set a configuration for the plurality of subsegments;
• and
• f) cause physical creation of a metrology mark instance having the configuration for the plurality of subsegments, cause physical creation of a patterning device to create at least part of the metrology mark instance, or provide a signal representing, or based on, the configuration for the plurality of subsegments to a tool or system for use by the tool or system to enable creation of the metrology mark instance or of the patterning device.

A computer program product comprising a non-transitory computer readable medium having instructions therein, the instructions, when executed by a computer system, configured to cause the computer system to at least:

• obtain an initial version of a characteristic function of a metrology mark disposed within a layer stack for use in a lithography process, wherein the characteristic function comprises:
• a change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the layer stack, the reflected beam being a beam reflected from the metrology mark and passing through the layer stack, or
• a change in angular reflectance of the reflected beam as a function of a change in thickness of the stack;
• iteratively perturb one or more variables of the metrology mark and/or of the layer stack and update the characteristic function based upon the perturbation, until a further version of the characteristic function is determined to set a configuration for the metrology mark;
• and
• cause physical creation of a metrology mark instance having the configuration for the metrology mark, cause physical creation of a patterning device to create at least part of the metrology mark instance, or provide a signal representing, or based on, the configuration for the metrology mark to a tool or system for use by the tool or system to enable creation of the metrology mark instance or of the patterning device.