DMD Photomask Correction for EUV Yield
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Solution Overview
Problem
The challenge in the semiconductor industry is to effectively correct defects in reflective photomasks used in extreme ultraviolet (EUV) photolithography, which can lead to defects in semiconductor devices due to errors in the manufacturing process, necessitating a technique to improve the yield of EUV photomasks by correcting critical dimensions.
Innovation Solution
A photomask processing apparatus and method utilizing a digital micromirror device (DMD) to selectively switch mirror blocks between on and off states to reflect light onto target correction regions of a photomask, allowing for precise correction of critical dimensions by controlling the temperature and etching process, thereby improving the accuracy and yield of EUV photomasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a reflective photomask is used in EUV lithography, then fine patterns can be transferred to the wafer, but defects in the photomask cause defects in the manufactured devices
Solution Approach 1:
The patent applies preliminary action by detecting patterns with incorrect critical dimensions before the photomask is used for manufacturing, and correcting these defects in advance. The inspection unit identifies patterns outside the critical dimension range, and the correction unit repairs them before they can cause device defects, thus preventing reliability issues while maintaining manufacturing precision.
Solution Approach 2:
The patent implements feedback by using the inspection unit to continuously monitor the critical dimensions of patterns on the photomask, comparing them against target specifications, and feeding this information back to the correction unit. This closed-loop system ensures that any deviations are detected and corrected, maintaining both pattern transfer accuracy and device yield.
2Measurement precision
If manual inspection and correction methods are used for photomask patterns, then individual defects can be addressed, but the process is time-consuming and inefficient
Solution Approach 1:
The patent replaces manual mechanical inspection and correction methods with an automated optical and computational system. The inspection unit uses optical imaging to detect patterns, and the correction unit applies automated repair techniques, eliminating the need for time-consuming manual operations while maintaining high measurement precision and significantly improving productivity.
Solution Approach 2:
The patent changes the operational parameters from manual to automated processing by implementing a systematic workflow where the inspection unit rapidly captures images and the correction unit automatically applies repairs based on algorithmic analysis. This parameter change from manual to automated operation maintains detection accuracy while dramatically increasing correction speed and throughput.
3Reliability
If the entire photomask is inspected and corrected, then all potential defects are addressed, but the processing time and resources increase significantly
Solution Approach 1:
The patent applies local quality by focusing inspection and correction efforts only on specific regions of the photomask where patterns fall outside the critical dimension range. Rather than uniformly processing the entire photomask, the system identifies and targets only the defective local areas, maintaining overall photomask quality while significantly reducing processing time and resource consumption.
Solution Approach 2:
The patent implements partial action by performing inspection and correction only on the necessary portions of the photomask that contain patterns with incorrect critical dimensions. This selective approach applies the minimum necessary action to achieve the desired quality level, avoiding unnecessary processing of already-compliant areas and thus reducing overall processing time while maintaining reliability.
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 solution enables simultaneous correction of multiple target correction patterns, increasing the precision and efficiency of the photomask processing, thereby enhancing the yield and reducing the time required for critical dimension correction in EUV photomasks.
Implementation Method 1
each of the plurality of mirror blocks is configured to, in the on state, reflect the emitted light toward the first surface of the photomask and, in the off state, reflect the emitted light toward outside of the first surface of the photomask
Implementation Method 2
a light source configured to emit light along an optical axis
Data Source
AI summary
Provided is a photomask processing apparatus including a light source, a photomask including a first surface provided with a plurality of patterns, an inspector configured to detect a target correction region including at least one target correction pattern, and a digital micromirror device (DMD) including a plurality of mirror blocks, and the DMD is further configured to switch, to the on state, mirror blocks corresponding to the target correction region of the first surface of the photomask among the plurality of mirror blocks, and switch, to the off state, mirror blocks corresponding to a non-correction region among the plurality of mirror blocks, the non-correction region being a region other than the target correction region on the first surface of the photomask.