Lithography Focus Control Using Optical and Acoustic Surface Profiling
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Solution Overview
Problem
Variations in the topography of semiconductor substrates and photo-sensitive layers cause focus errors during lithographic processes, leading to incorrect pattern projection and reduced quality of exposure operations.
Innovation Solution
A method involving the formation of a photo-sensitive layer on a semiconductor substrate, where optical and acoustic transceivers obtain profiles of the substrate and photo-sensitive layer surfaces, enabling calculation of a vertical displacement profile to dynamically focus the irradiation light source at the desired focal plane, and adjusting the substrate stage accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lithographic exposure is performed on substrates with variable topography, then productivity is maintained, but manufacturing precision deteriorates due to focus errors and imaging errors
Solution Approach 1:
The patent implements dynamic focus adjustment by continuously varying the focal plane position during scanning exposure to match the local topography of the substrate and photoresist layer. The focal plane is dynamically adjusted based on real-time measurements of surface variations, allowing the system to maintain manufacturing precision while processing substrates with variable topography at high productivity.
Solution Approach 2:
The system changes the focal plane parameter dynamically during the exposure process. By adjusting the focal plane position as a variable parameter rather than keeping it fixed, the system adapts to local topography variations, maintaining pattern projection accuracy across the entire substrate surface while preserving exposure throughput.
2Device complexity
If the focal plane is fixed during exposure, then device complexity is reduced, but manufacturing precision deteriorates due to inability to compensate for thickness variations
Solution Approach 1:
The focus control system transitions from a static fixed focal plane to a dynamic adjustable focal plane that can be varied during scanning. This dynamic capability allows the system to compensate for photoresist thickness variations and substrate topography, significantly improving exposure quality while adding only moderate complexity through automated control.
Solution Approach 2:
The system incorporates feedback from surface measurements to automatically adjust the focal plane position. By measuring the actual topography and photoresist thickness and using this information to control the focal plane, the system achieves high manufacturing precision without requiring overly complex manual intervention or excessive hardware complexity.
3Productivity
If scanning speed is increased to improve productivity, then exposure throughput increases, but measurement precision deteriorates due to reduced time for topography assessment
Solution Approach 1:
The system performs preliminary measurement of the substrate and photoresist surface topography before the actual exposure process. By obtaining accurate surface profiles in advance, the system can plan the focal plane trajectory ahead of time, allowing high scanning speeds during exposure without compromising measurement precision, as the critical measurements are completed beforehand.
Solution Approach 2:
The exposure process is segmented into distinct phases: measurement phase and exposure phase. During the measurement phase, the system moves slowly to accurately assess surface topography. During the exposure phase, the system moves quickly while following a pre-calculated focal plane trajectory. This segmentation allows both high measurement precision and high productivity to be achieved in different stages of the process.
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
Improves scanning accuracy and ensures the focal plane remains at the middle plane of the photo-sensitive layer, enhancing the quality of exposure operations by compensating for thickness variations.
Implementation Method 1
an optical transceiver emits a light and obtains a first profile of a first surface of the semiconductor substrate
Implementation Method 2
an acoustic transceiver emits matter waves and obtains a second profile of a top surface of the photo-sensitive layer
Data Source
AI summary
The present disclosure provides an apparatus for manufacturing a semiconductor structure. The apparatus includes a stage, an optical transceiver over the stage, configured to obtain a first profile of a first surface of a substrate, an acoustic transceiver over the stage, configured to obtain a second profile of a top surface of a photo-sensitive layer over the substrate, wherein the stage is adapted to be displaced based on the first profile and the second profile.