Charged-particle beam deflection voltage correction for pattern drift
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Solution Overview
Problem
Conventional electron beam exposure systems face challenges in maintaining high dimensional accuracy and pattern precision due to direction and pattern drift errors during the fabrication of photomasks and other patterned articles, which affect the quality of semiconductor devices.
Innovation Solution
A charged-particle beam method that involves moving a stage with a target sample, irradiating it with a charged-particle beam, and controlling the beam's direction drift by applying a deflection voltage based on the stage's movement direction and shot density, with correction processes to compensate for errors in direction and pattern drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a charged-particle beam is used to transfer patterns to a substrate, then fine patterns can be formed, but direction drift and pattern drift errors occur that reduce manufacturing precision
Solution Approach 1:
The system performs preliminary measurement of direction drift and pattern drift before the actual exposure process. Drift values are measured using a test substrate with marks, and these measured values are stored and used for correction during subsequent production exposure, allowing the system to prepare correction data in advance
Solution Approach 2:
The system implements a feedback mechanism where drift values are continuously measured and used to adjust deflection voltages. The measured drift information feeds back to the control system, which automatically adjusts the beam deflection to compensate for drift, creating a closed-loop control system that maintains pattern transfer accuracy
Solution Approach 3:
The system changes the deflection voltage parameter based on measured drift values. By adjusting the deflection voltage in response to measured drift, the system dynamically compensates for beam direction instability and maintains manufacturing precision throughout the exposure process
2Area of stationary object
If the stage is moved to scan the beam across the substrate, then large area exposure is achieved, but direction drift occurs that affects pattern accuracy
Solution Approach 1:
The system measures direction drift values before exposure using a test substrate with marks positioned at different locations. These pre-measured drift values corresponding to different stage positions are stored and used to correct beam direction during actual exposure, allowing compensation for position-dependent drift
Solution Approach 2:
The system applies different deflection voltage corrections for different regions of the substrate. Drift values are measured and stored for specific mark positions, and during exposure, the appropriate regional correction is applied based on the current stage position, allowing localized compensation for direction drift across the large exposure area
3Reliability
If deflection voltage is applied to correct direction drift, then beam direction stability is improved, but additional control complexity is introduced
Solution Approach 1:
The system uses itself to measure and correct drift. The same charged-particle beam exposure system that is affected by drift also performs the drift measurement using built-in marks on a test substrate, and uses its own deflection voltage control to correct the measured drift, eliminating the need for external measurement equipment
Solution Approach 2:
The system combines the drift measurement function and the exposure function into a single integrated process. The measurement of direction drift and pattern drift is performed using the same beam and hardware as the exposure process, merging calibration and production operations to reduce overall system complexity
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 method ensures high reliability and precision in transferring desired patterns by correcting for direction and pattern drift, enabling the formation of fine patterns that would otherwise be impossible to achieve, thereby improving the accuracy and quality of patterned articles like photomasks.
Implementation Method 1
regulating a deflection voltage, which is applied to the charged-particle beam to deflect the charged-particle beam
Data Source
AI summary
A charged-particle beam exposure method includes providing a sample that has patterns having shot densities different from each other, using the sample to obtain pattern drift values correlated with the shot densities, and irradiating the sample with a charged-particle beam to perform an exposure process on the sample. The irradiating of the sample with the charged-particle beam is carried out while a deflection voltage, which is applied to the charged-particle beam to deflect the charged-particle beam, is corrected based on the pattern drift value corresponding to a shot density of a pattern to be formed on the sample.