Photomask Defect Repair Shape Control for Precise Edge Profiles
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Solution Overview
Problem
Existing methods for processing defects in microlithographic photomasks struggle to achieve precise edge shapes and steepness, particularly when using particle beam-induced processing, due to limitations in controlling the particle beam's settling behavior.
Innovation Solution
A method that utilizes a process gas activated with a particle beam, controlled by a deflection unit and a control unit with a specified bandwidth, to guide the particle beam over the photomask. This method involves providing an image of the photomask, ascertaining a repair shape based on the control bandwidth, and directing the particle beam at specific pixels of the repair shape to activate the process gas for defect processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If particle beam-induced processing is used to repair defects in photomasks, then defect processing capability is improved, but edge shape precision and steepness deteriorate due to uncontrolled beam settling behavior
Solution Approach 1:
The patent applies preliminary action by pre-calculating and compensating for the beam settling behavior before actual defect repair. The control unit determines a compensated beam trajectory that anticipates the settling effect, adjusting the beam path in advance to ensure accurate edge formation despite the beam's natural settling during switching transitions.
Solution Approach 2:
The patent implements feedback by using detected edge information from the photomask to dynamically adjust the particle beam trajectory. The control unit continuously monitors the beam position and settling behavior, then modifies subsequent beam paths based on this feedback to maintain precise edge shapes during defect repair operations.
2Productivity
If particle beam is rapidly switched between pixels for efficient defect repair, then processing speed is improved, but beam settling behavior causes edge shape deterioration
Solution Approach 1:
The system performs preliminary calculation of the compensated beam trajectory that accounts for settling effects before rapid pixel switching begins. This pre-computation allows the beam to be rapidly switched between pixels for high productivity while the pre-determined compensation path prevents edge shape deterioration from settling behavior.
Solution Approach 2:
The patent applies dynamics by making the beam trajectory adaptive and dynamic rather than static. The control unit dynamically adjusts the beam path in real-time during rapid pixel switching, modifying the trajectory on-the-fly to compensate for settling effects while maintaining high processing speed through efficient rapid switching.
3Productivity
If control bandwidth is increased to improve beam response, then processing efficiency is improved, but control complexity increases
Solution Approach 1:
The control unit performs preliminary determination of the compensated beam trajectory, calculating the necessary compensation for settling behavior in advance. This pre-calculation approach allows for higher effective control bandwidth and processing efficiency while managing control complexity by consolidating the compensation logic into a centralized control unit rather than requiring complex distributed control systems.
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 method achieves improved edge shapes and steepness by considering the control bandwidth, allowing for more precise defect repair in microlithographic photomasks, which is critical for maintaining the quality of integrated circuits produced using these masks.
Implementation Method 1
a particle beam, in particular an electron beam, and an etching gas are provided at a site on the photolithographic mask to be etched. 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
The processing of the defect comprises, in particular, an etching of the defect, within the scope of which material is locally ablated from the photomask
Data Source
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AI summary
A method for processing a defect (D) of a microlithographic photomask (100) is disclosed, wherein a process gas is activated with the aid of a particle beam (802), wherein a control unit (828) is provided for controlling a deflection unit (816) with a control bandwidth (GF), wherein the deflection unit (816) for deflecting the particle beam (802) is configured to guide the particle beam (802) over the photomask (100), including the following steps: a) providing (S1) an image (200') of at least a portion of the photomask (100), b) ascertaining a repair shape (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) in the image (200') on the basis of the control bandwidth (GF), wherein the repair shape (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) comprises the defect (D), and c) providing the particle beam (802) at m pixels (410) of the repair shape (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) with the aid of the deflection unit (816), and activating the process gas for the purpose of processing the defect (D).