Photomask Defect Repair Using Multi-Voltage Electron Beam Imaging
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Solution Overview
Problem
The production of microlithographic photomasks with structure dimensions in the nanometer range is complex and costly due to the need for defect-free masks, and existing methods for defect repair in these masks are not precise enough, especially for EUV and DUV lithography applications.
Innovation Solution
A method involving electron beam-induced processing using varying acceleration voltages to repair defects in microlithographic photomasks by providing an activating electron beam and a process gas, allowing for precise etching or deposition, and subsequent imaging to assess the quality of the repair, enabling better edge region processing and depth analysis of the photomask structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single acceleration voltage is used for electron beam processing, then the process is simple and fast, but the precision of defect repair and quality assessment is insufficient
Solution Approach 1:
The electron beam processing is segmented into two distinct stages: a first stage using a first acceleration voltage for defect repair (etching or deposition), and a second stage using a second acceleration voltage for quality assessment (imaging). This segmentation allows each stage to be optimized independently for its specific function, thereby improving overall precision without requiring the entire system to be overly complex.
Solution Approach 2:
The invention changes the acceleration voltage parameter between two stages: using a first acceleration voltage for the repair process and a second acceleration voltage for imaging. This parameter change enables optimization of the electron beam properties for each specific task, improving repair precision and assessment accuracy while maintaining manageable system complexity through controlled parameter variation.
2Length of stationary object
If high acceleration voltage is used for imaging, then penetration depth is sufficient for deep structures, but surface detail resolution decreases
Solution Approach 1:
The invention dynamically adjusts the acceleration voltage based on the imaging requirements. By using a second acceleration voltage that is different from the first, the system can optimize the electron beam energy for surface detail resolution when imaging, while maintaining the capability for deeper penetration when repair is needed. This dynamic adjustment resolves the contradiction between penetration depth and surface resolution.
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 enhances the precision of defect repair in microlithographic photomasks, improving the quality of the repaired defects by allowing for accurate etching or deposition, and provides immediate quality assessment, ensuring the photomasks meet specified quality standards for EUV and DUV lithography applications.
Implementation Method 1
The particle beam activates a local chemical reaction between a material of the photolithographic mask and the etching gas, as a result of which material is locally ablated from the photolithographic mask
Implementation Method 2
Interactions of the electrons of the electron beam (primary beam) with the material of the photomask for example comprise an interaction of the electrons of the primary beam with atoms of the object to be examined, with secondary electrons being produced
Data Source
AI summary
A method for electron beam-induced processing of a defect of a microlithographic photomask, including the steps of:a) providing an activating electron beam at a first acceleration voltage (EHT1) and a process gas in the region of a defect of the photomask for the purpose of repairing the defect, andb) producing at least one image of the photomask, in which the region of the defect is captured at least in part, by providing an electron beam at at least one second acceleration voltage (e.g., EHT2, EHT3, EHT4) which differs from the first acceleration voltage (EHT1), for the purpose of determining a quality of the repaired defect.