Determination of scanning error in scanner by reticle rotation

A method of characterizing a lithographic scanning system, comprising the steps of:

• printing a first pattern using a reticle having a first orientation with respect to the lithographic scanning system;
• measuring a critical dimension of the first pattern at a plurality of points;
• printing a second pattern using the reticle having a second orientation with respect to the lithographic scanning system different than the first orientation;
• measuring a critical dimension of the second pattern at the plurality of points;
• measuring a critical dimension on the reticle at a plurality of points corresponding to the plurality of points of the first and second patterns;
• determining a reticle critical dimension component and a non-reticle critical dimension component of the patterns at the plurality of points;
• wherein determining a non-reticle critical dimension component comprises:
• (a) creating four equations with four unknowns using the measured critical dimension data as follows:
• CD(pattern 1, point 1)=Rpoint 1+NRpoint 1,
• CD(pattern 1, point 2)=Rpoint 2+NRpoint 2,
• CD(pattern 2, point 1)=Rpoint 1+NRpoint 2,
• CD(pattern 2, point 2)=Rpoint 2+NRpoint 1,
• wherein CD comprises the measured critical dimension at the two points, NR comprises the non-reticle critical dimension component, and R comprises a reticle critical dimension component;
• (b) using the measured reticle critical dimension at the plurality of points to reduce the four equations to a three equation, three unknown linear system;
• (c) solving the linear equations to identify the non-reticle critical dimension component of the features at the plurality of points;
• (d) repeating steps (a), (b) and (c) until the non-reticle critical dimension components are identified for the plurality of points;
• and
• determining a scanning system critical dimension component of the patterns using the non-reticle critical dimension component data along a plurality of points corresponding to a scanning direction of the lithographic scanning system.

A method of identifying components that make up a critical dimension of a feature in a lithographic scanning system, comprising the steps of:

• printing a first pattern onto a substrate using a reticle having a first orientation with respect to the lithographic scanning system, wherein the reticle contains features thereon which are rotationally symmetric about a specified angle of rotation;
• measuring a critical dimension of the first pattern at a first plurality of points across the substrate;
• rotating the reticle to a second orientation with respect to the lithographic scanning system different than the first orientation, wherein an angle between the first and second orientation is equal to the specified angle;
• printing a second pattern onto another substrate using the reticle at the second orientation;
• measuring a critical dimension of the second pattern at a second plurality of points across the another substrate, wherein the first and second plurality of points positionally correspond to one another;
• measuring a critical dimension on the reticle at a plurality of points corresponding to one of the first and second plurality of points;
• determining a reticle critical dimension component and a non-reticle critical dimension component at the first and second plurality of points using the measured critical dimension data at the first and second plurality of points;
• and
• determining a scanning system critical dimension using the non-reticle critical dimension component along a plurality of points corresponding to a scanning direction of the lithographic scanning system.