Photolithography Patterning Device Shadow Angle Compensation
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Solution Overview
Problem
Current photolithography techniques face challenges in accurately transferring patterns onto substrates due to displacement and dimension errors caused by effective shadow angles and slit position dependencies, leading to misalignment and variations in critical dimension and position shifts during pattern transfer.
Innovation Solution
The method involves defining features within the patterning device with specific dimensions and orientations to compensate for displacement and dimension errors by calculating the effective shadow angle and adjusting these features to optimize image transfer, using a computer program to generate an adjustment model for the lithographic projection apparatus, and employing a measurement device to detect and correct for errors during pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography pattern transfer is used, then the patterning process can be completed, but displacement and dimension errors occur due to effective shadow angles and slit position dependencies
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-adjusting the features on the patterning device to compensate for expected displacement and dimension errors. The method involves calculating effective shadow angles for a plurality of points on the patterning device and adjusting features beforehand to compensate for errors that would otherwise occur during pattern transfer, rather than attempting to correct errors after they occur during the exposure process
Solution Approach 2:
The patent employs parameter changes by modifying the dimensions and positions of features on the patterning device based on calculated effective shadow angles. The method adjusts critical parameters such as feature size, position, and orientation to compensate for the effects of shadow angles and slit position dependencies, thereby maintaining manufacturing precision despite the inherent optical limitations
2Measurement precision
If alignment actions are performed to accurately position the reticle with respect to the substrate, then alignment accuracy is improved, but the process complexity increases due to multiple measurement and adjustment steps
Solution Approach 1:
The patent reduces alignment process complexity by performing preliminary compensation adjustments on the patterning device features before the alignment and exposure process. By pre-adjusting features to account for effective shadow angles, the patent reduces the need for complex real-time measurements and adjustments during the alignment process, thereby simplifying the overall alignment procedure while maintaining high accuracy
3Manufacturing precision
If features are adjusted to compensate for effective shadow angles, then pattern transfer accuracy is improved, but the manufacturing complexity of the patterning device increases
Solution Approach 1:
The patent addresses the manufacturing complexity by systematically adjusting feature parameters (dimensions, positions, orientations) based on pre-calculated effective shadow angles. While this does increase the complexity of patterning device fabrication compared to conventional approaches, the method provides a deterministic and calculable approach to compensation, allowing for automated design and manufacturing processes that can handle the increased parameter complexity in a controlled manner
Data Source
AI summary
A method of generating a photolithography patterning device for transferring a pattern formed in the patterning device onto a substrate utilizing a lithographic projection apparatus includes defining features within the pattern formed in the device, wherein the features have dimensions and orientations chosen to create a desired image on the substrate during pattern transfer; and adjusting the dimensions of the features to compensate the desired image for displacement and dimension errors introduced by the effective shadow angle of the radiation on the features during pattern transfer or correlated to the position of the features within the exposure slit during pattern transfer. A measurement device for determining the position of a target image on or proximate a substrate in a lithographic projection apparatus, wherein the target image is formed by features on a patterning device, includes a detector configured to measure the position of the target image on or proximate the substrate, wherein the detector compensates the measured position of the target image for displacement and dimension errors introduced by the effective shadow angle of the radiation on the features of the patterning device during pattern transfer or correlated to the position of the features within the exposure slit during pattern transfer. A lithographic apparatus includes a measurement device.