Projection Lens Wavefront Manipulator for Overlay Accuracy
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Solution Overview
Problem
Current microlithographic projection exposure methods face challenges in achieving high overlay accuracy, particularly in double patterning techniques, which can lead to manufacturing errors and increased costs due to insufficient overlay precision.
Innovation Solution
A projection lens with a wavefront manipulation system and a sensitivity adaptation system that allows for controllable wavefront adjustment and sensitivity modification, enabling precise imaging and adaptation to changes in mask position and deformation, thereby improving overlay accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If double patterning method is used to reduce structure dimensions, then productivity is improved, but overlay accuracy deteriorates leading to manufacturing errors
Solution Approach 1:
The system performs preliminary measurement of the actual mask position using a sensor before the exposure process. Based on this measured position, the control system pre-calculates and sets the appropriate sensitivity value for the manipulator, ensuring that overlay errors are compensated in advance rather than corrected after errors occur
Solution Approach 2:
The system implements a feedback mechanism where the actual mask position is continuously monitored by a sensor during the exposure process. This position information is fed back to the control system, which adjusts the manipulator's sensitivity in real-time to maintain optimal overlay accuracy throughout the double patterning process
2Manufacturing precision
If manipulator sensitivity is increased to reduce overlay errors, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system employs dynamic sensitivity adjustment where the manipulator's sensitivity is not fixed but varies based on the measured mask position. The control system automatically selects from a plurality of sensitivity values stored in memory, optimizing the manipulator's response characteristics for each specific exposure condition without requiring manual intervention or complex mechanical modifications
Solution Approach 2:
The system changes the operational parameters of the manipulator by selecting different sensitivity values from a predefined set. This allows the system to adapt to varying mask positions and exposure conditions by modifying the electrical/control parameters rather than physically redesigning the manipulator mechanism, thereby maintaining simplicity while achieving high precision
3Manufacturing precision
If wavefront manipulation is applied to correct imaging properties, then manufacturing precision is improved, but adaptability to varying operating conditions deteriorates
Solution Approach 1:
The system dynamically adapts to varying operating conditions by continuously monitoring mask position and adjusting manipulator sensitivity accordingly. This dynamic adaptation allows the wavefront manipulation system to maintain optimal imaging quality across different mask positions, illumination conditions, and exposure parameters without requiring manual reconfiguration
Solution Approach 2:
The control system is designed to handle multiple exposure conditions and mask positions using a single integrated system that automatically selects appropriate sensitivity values. This universal approach allows the same wavefront manipulation system to effectively correct imaging properties across various operating conditions, eliminating the need for multiple specialized systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables reduced overlay errors and improved imaging quality, allowing for more precise and efficient microlithographic processes, even under varying operating conditions, thus enhancing the production of finely structured components like semiconductor components.
Implementation Method 1
The wavefront manipulation system has a manipulator having a manipulator surface arranged in the projection beam path. The manipulator includes an actuating device which renders it possible to modify the surface form and/or the refractive index distribution of the manipulator surface in a reversible manner.
Implementation Method 2
The radiation modified by the pattern travels through the projection lens as projection radiation, the projection lens imaging the pattern with a reduced scale onto the substrate to be exposed.
Implementation Method 3
use is usually made of catadioptric projection lenses which have both transparent refractive optical elements with refractive power (lens elements) and reflective elements with refractive power, i.e. curved mirrors. Typically, at least one concave mirror is contained.
Data Source
AI summary
A projection lens images a pattern of a mask arranged in the region of an object plane of the projection lens into an image plane of the projection lens via electromagnetic radiation with a work wavelength λ<260 nm. The projection lens has a multiplicity of optical elements with optical surfaces. The projection lens also has a wavefront manipulation system for controllable influencing of the wavefront of the projection radiation travelling from the object plane to the image plane. The wavefront manipulation system has a manipulator having a manipulator element and an actuating device or reversibly changing an optical effect of the manipulator element on radiation of the projection beam path.