Electron Beam Exposure Dose Map Correction for Pattern Fidelity
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Solution Overview
Problem
In semiconductor device fabrication, existing photolithography processes face challenges in accurately transferring patterns from photomasks to wafers due to minor processing errors, leading to discrepancies between the target and actual patterns formed, which affect the fidelity and precision of the resulting semiconductor devices.
Innovation Solution
The method involves creating a first dose map representing the target pattern and a second dose map accounting for energy doses from overlapping beams, allowing for controlled exposure of photoresist regions with varying energy doses to correct and improve the pattern fidelity, using techniques like Variable Shaped Beam (VSB) or Multi-Beam Mask Writer (MBMW) exposure methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography exposure is used, then the process is simple and fast, but the pattern transfer accuracy deteriorates due to processing errors
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal exposure parameters (dose, focus, NA) in a lookup table before the actual exposure process. The system retrieves pre-computed correction values based on measured wafer conditions and applies them during exposure, avoiding real-time complex calculations while achieving high precision pattern transfer
Solution Approach 2:
The system implements feedback by measuring actual wafer conditions (position, focus, dose) during exposure, comparing them against target values, and dynamically adjusting exposure parameters using pre-stored correction data from lookup tables. This closed-loop control compensates for processing errors and maintains high pattern fidelity
2Manufacturing precision
If exposure parameters are adjusted to correct pattern discrepancies, then pattern fidelity improves, but the exposure process time increases
Solution Approach 1:
The patent pre-computes exposure correction parameters for various wafer conditions and stores them in lookup tables before production. During actual exposure, the system only needs to retrieve pre-calculated values based on measured conditions, avoiding time-consuming real-time optimization while maintaining high pattern fidelity
Solution Approach 2:
The system uses self-service by automatically selecting appropriate exposure parameters from pre-stored lookup tables based on real-time wafer condition measurements. The pre-computed correction data enables the system to self-adjust without external intervention or complex real-time calculations, balancing precision and speed
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
This approach enhances the accuracy and fidelity of pattern transfer, minimizing production costs and improving the precision of semiconductor devices by adjusting energy doses based on the second dose map, resulting in improved productivity and pattern quality.
Implementation Method 1
exposing the photoresist to beams of energy emitted by a light source of an exposure apparatus
Data Source
AI summary
An exposure method includes designing a target pattern to be formed on a substrate, producing a first dose map having first dose values of beams of energy, e.g., electron beams, creating from the first dose map a second dose map having second dose values different from the first dose values, and irradiating regions of a layer of photoresist on the substrate with overlapping beams to expose the regions to doses of energy having values based on the second dose values. The photoresist layer may then be developed and used an etch mask. The etch mask may be used to etch a mask layer on a transparent substrate to form a reticle.