Source Map Transfer Calibration for Programmable Illumination Distortion
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Solution Overview
Problem
The distortion of Programmable Illumination Systems (PIS) in lithographic tools causes undesirable exposure effects and reduces yield in IC manufacturing, as users lack the necessary tools to account for PIS distortion in current Optical Proximity Correction (OPC) systems.
Innovation Solution
A simulation method is developed to calibrate a Source Map Transfer Model (SMTM) using ordered source maps (OSM) and actual processing results, enabling a PIS model to simulate PIS entities and optimize source masks, thereby mitigating distortion impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Source Mask Optimization (SMO) is pursued using current OPC tools, then resolution improvement is achieved, but exposure quality deteriorates due to PIS distortion
Solution Approach 1:
The patent introduces a PIS model as an intermediary component that bridges the gap between SMO optimization and actual exposure results. This model simulates the distortion characteristics of the Programmable Illumination System, allowing OPC tools to predict and compensate for PIS-induced errors without modifying the physical PIS hardware.
Solution Approach 2:
The patent creates a virtual copy of the PIS system through the PIS model, which replicates the distortion behavior of the actual physical PIS. This copying approach enables users to simulate and analyze PIS effects without requiring access to or modification of the expensive, proprietary physical PIS hardware.
2Device complexity
If PIS distortion is not accounted for in OPC tools, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent segments the lithography system into distinct functional components: the physical PIS hardware (which remains unchanged and complex) and the virtual PIS model (which is simpler and software-based). This segmentation allows OPC tools to incorporate distortion compensation through the separate, manageable PIS model without increasing overall system complexity.
3Reliability
If physical PIS hardware is modified to reduce distortion, then exposure quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical/mechanical modifications to the PIS hardware with a software-based PIS model that mathematically simulates and compensates for distortion. This substitution avoids the complexity and cost of modifying proprietary physical hardware while achieving the same exposure quality improvement.
Data Source
AI summary
The present invention relates to a simulation method for a programmable illumination system and a source mask optimization method. The simulation method includes: calibrating the parameters of the source map transfer model (SMTM) in the first simulation model based on the ordered source map (OSM) sample and the actual processing result; wherein the actual processing result is obtained by inputting the OSM sample to the physical lithographic tool and monitoring the processing process of the physical lithographic tool, the first simulation model is configured to output simulation processing results corresponding to the actual processing results, the first simulation model at least includes the SMTM; and the calibrated SMTM is used as a programmable illumination system (PIS) model. In the invention, by using reference data to calibrate the parameters of the SMTM in the first simulation model to obtain the PIS model.