Method for adjusting the overlay of two mask planes in a photolithographic process for the production of an integrated circuit
View Patent ↗The present invention provides a method for optimizing the overlay adjustment of two mask planes in a photolithographic process for the production of an integrated circuit having the following steps: provision of a substrate (S) with at least one first mask plane (ME), which has been patterned by exposure of a first mask using a first exposure device; orientation of a second mask (M), which is provided for the patterning of a second mask plane using a second exposure device, with respect to the first mask plane (ME); measurement of the overlay between the first mask plane (ME) and the second mask (M); analysis of the measured overlay taking account of error data (FAD, FXD, FBD, FYD) provided, in advance regarding errors (FA, FX, FB, FY) of the first and second masks and/or errors of the first and second exposure devices; carrying out of a correction of the orientation of the second mask (M) depending on the result of the analysis.
1. A method for adjusting the overlay of two mask planes in a photolithographic process for the production of an integrated circuit, the method comprising the steps of:
providing a substrate with at least one first mask plane, which has been patterned by exposure of a first mask using a first exposure device;
orientating a second mask, which is provided for patterning a second mask plane using a second exposure device, with respect to the first mask plane;
measuring an overlay between the first mask plane and the second mask plane;
providing error data, which are stored in a database, regarding errors of the first and second masks and/or errors of the first and second exposure devices by a measurement by means of a common reference grid;
analyzing the measured overlay taking account of the error data provided in advance regarding the errors of the first and second masks and/or errors of the first and second exposure devices;
comparing a result of said analyzing with a predetermined specification; and
performing a correction step for correcting the orientation of the second mask depending on a result of said comparing.
2. The method of claim 1 , wherein said analyzing provides a division into correctable and noncorrectable errors.
3. The method of claim 2 , further comprising interrupting the photolithographic process if the result of said comparing lies outside the specification and, at the same time, only noncorrectable errors are present.
4. The method of claim 1 , further comprising interrupting the photolithographic process if a number of correction steps exceeds a predetermined value or a predicted result is assessed as insufficient.