Electron Beam Exposure System Shot Density Compensation
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Solution Overview
Problem
Conventional electron beam exposure systems suffer from pattern position and beam drift errors, which affect the accuracy of mask patterns formed on photomasks during the photolithography process, leading to discrepancies between exposure and mask layouts.
Innovation Solution
An electron beam exposure system with a data processing part that generates control parameters to drive the exposure process without pattern position and beam drift errors, using shot density calculations to adjust stage acceleration and electron beam deflection width, and a controlling part to implement these parameters, ensuring precise alignment and beam control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electron beam exposure systems are used, then the exposure process can be performed, but pattern position errors and beam drift errors occur leading to discrepancies between exposure layout and mask layout
Solution Approach 1:
The system performs preliminary calculations of shot density distribution across the exposure layout before actual exposure. Control parameters are pre-computed based on these density calculations, allowing the system to anticipate and compensate for potential pattern position errors and beam drift errors before they occur during the exposure process.
Solution Approach 2:
The system dynamically adjusts exposure control parameters based on calculated shot density values. By changing parameters such as beam current, exposure time, or stage velocity in response to varying pattern densities, the system maintains consistent pattern formation quality across different regions of the exposure layout, preventing both pattern position errors and beam drift errors.
2Ease of operation
If uniform exposure parameters are used across the entire exposure layout, then the exposure process is simple, but pattern position errors occur at interfaces between dense and sparse regions
Solution Approach 1:
The system divides the exposure layout into regions with different shot density characteristics and applies locally optimized control parameters to each region. At interfaces between dense and sparse regions, the system calculates transition parameters that smoothly bridge the density difference, preventing pattern position errors while maintaining operational simplicity through automated parameter selection.
Solution Approach 2:
The system transitions from static uniform exposure parameters to dynamic region-dependent parameters. By automatically identifying dense and sparse regions and adjusting control parameters accordingly, the system maintains exposure simplicity for the user while achieving high pattern position accuracy through adaptive parameter changes at region boundaries.
3Productivity
If the stage acceleration is increased to improve productivity, then exposure speed increases, but beam drift errors occur due to deflector contamination
Solution Approach 1:
The system calculates shot density distributions and predicts potential beam drift errors caused by deflector contamination before exposure. By pre-computing compensatory control parameters that counteract the expected beam drift, the system maintains beam position accuracy even when operating at high stage acceleration speeds that would otherwise cause errors due to contaminated deflectors.
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 system effectively reduces pattern position and beam drift errors, ensuring accurate formation of mask patterns by optimizing stage movement and electron beam deflection based on shot density differences between dense and sparse regions, thereby preventing discrepancies between exposure and mask layouts.
Implementation Method 1
a photolithography process is performed to transfer mask patterns formed on a photomask onto a photoresist layer on a substrate
Implementation Method 2
a deflector that deflects the electron beam in a tilted direction relative to the mask layer
Data Source
AI summary
An exposure system includes a data processing part that forms an exposure layout and an exposure part that irradiates an electron beam at a photoresist layer according to the exposure layout. The data processing part generates a control parameter for driving the exposure part without a pattern position error and a beam drift error and to prevent a discrepancy between the exposure layout and a mask layout to be formed in the photoresist layer. A controlling part controls the exposure part according to the control parameter.