Process control system including process condition determination using attribute-relative process condition

A method of forming an integrated circuit, the method comprising:

• using one or more processor-based systems, obtaining first historical energy conditions and second historical energy conditions, wherein the first historical energy conditions are of previous photolithography processing corresponding to a target value of a process attribute, and the second historical energy conditions are of previous photolithography processing corresponding to variable values of the process attribute;
• using the one or more processor-based systems, determining time-based weights, each time-based weight of the time-based weights being for a time-corresponding pair of a first historical energy condition of the first historical energy conditions and a second historical energy condition of the second historical energy conditions;
• using the one or more processor-based systems, calculating attribute-relative energy conditions, each attribute-relative energy condition of the attribute-relative energy conditions being based on the time-based weights, the first historical energy conditions, and the second historical energy conditions that correspond to a respective given value of the variable values of the process attribute;
• using the one or more processor-based systems, excluding outlier attribute-relative energy conditions of the attribute-relative energy conditions;
• using the one or more processor-based systems, determining an average energy condition from non-excluded attribute-relative energy conditions of the attribute-relative energy conditions;
• setting an energy condition of a subsequent photolithography process based on the average energy condition, the subsequent photolithography process corresponding to the target value of the process attribute;
• and
• performing the subsequent photolithography process on a semiconductor substrate, the subsequent photolithography process being based on the set energy condition.

A non-transitory computer readable medium comprising stored instructions, which when executed by one or more processors, cause the one or more processors to:

• obtain first historical process conditions and second historical process conditions from a database, wherein the first historical process conditions are of previous semiconductor processing corresponding to a target value of a process attribute, and the second historical process conditions are of previous semiconductor processing corresponding to variable values of the process attribute;
• determine time-based weights, each time-based weight of the time-based weights being for a time-corresponding pair of a first historical process condition of the first historical process conditions and a second historical process condition of the second historical process conditions;
• calculate attribute-relative process conditions, each attribute-relative process condition of the attribute-relative process conditions being a current process condition corresponding to a respective given value of the variable values of the process attribute plus a sum of weighted differences, each weighted difference of the weighted differences being a respective time-based weight of the time-based weights times a difference between a respective time-corresponding pair of the time-corresponding pairs, wherein for the respective time-corresponding pair, the second historical process condition corresponds to the respective given value of the variable values of the process attribute;
• exclude outlier attribute-relative process conditions of the attribute-relative process conditions;
• and
• determine an average process condition from non-excluded attribute-relative process conditions of the attribute-relative process conditions, wherein the average process condition is for a subsequent semiconductor process corresponding to the target value of the process attribute.