Advanced process control model incorporating a target offset term
An advanced process control (APC) architecture comprising a process model that incorporates a target offset term is provided. The APC architecture may be applied to a so-called develop inspect critical dimension (DICD) model using the target offset term to correct at least one exposure parameter on the occurrence of an abrupt event. A corresponding event may, for example, concern a modified reflectivity of processed substrates, for example due to a rework of substrates covered by amorphous carbon material.
1. A method, comprising:
providing a processed substrate having a rework status representative of a number of rework processes performed on said substrate; and
exposing a photoresist layer provided above said substrate, wherein at least one exposure parameter is determined by an advanced process controller at least on the basis of said rework status, wherein said advanced process controller comprises a process model comprising a target value and a target offset value to correct a time-dependent variation.
2. The method of claim 1 , wherein said target offset value represents an abrupt event.
3. The method of claim 2 , wherein said target offset value represents said rework status of said substrate.
4. The method of claim 3 , wherein said target offset value is obtained from test runs.
5. The method of claim 3 , wherein said target offset value is obtained from data analyses performed on critical dimension measurement data of developed photoresist features.
6. The method of claim 2 , wherein at least one of said target value and said target offset value further depends on the position on said substrate.
7. The method of claim 6 , wherein said at least one of said target value and said target offset value is listed in an exposure map.