Effective intra-field overlay compensation in lithography via mask-level thermal and mechanical control

With the continuous shrinkage of integrated circuit process nodes, overlay have become one of the most significant factors affecting lithography. In response to the limitations of traditional overlay correction methods, this paper proposes a novel intra-field overlay control approach based on the thermodynamic effects of the mask. By employing 143 pixel-level thermal tuning schemes and 16 stress application strategies, this method shows promise in addressing the lithographic accuracy degradation caused by overlay. We utilize a third-order overlay decomposition in the lithography field and establishes physical, mathematical, and statistical models. Simulation results show that the compensation effects in the X and Y directions achieve 98.28% and 99%, respectively, with compensation rates of 99%, 97%, and 83.96% for linear, quadratic, and higher-order terms. Multiple validations indicate that the average compensation effects in the X and Y directions are 97.99% and 98.08%, respectively. Additionally, the model identifies the key scenarios and compensation parameters that limit the third-order overlay, including K15, K19, and K20. Applying the method to 24 random datasets yielded residual overlay errors (|mean| + 3σ, X and Y directions) consistently <1 nm, meeting 14nm technology node and beyond as advanced nodes requirements. Future work will focus on optimizing the model using real nanoimprint lithography (NIL), surface plasmon lithography (SPL), or near-field lithography (NFL) machine data and exploring higher-order overlay correction effects.