EUV Photomask Repair Bias Control for Faster Defect Etching
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Solution Overview
Problem
Existing EUV lithography techniques face challenges in efficiently repairing EUV photomasks due to time-consuming and costly etching processes, which are required to remove defects without damaging the capping layer.
Innovation Solution
The method involves revising the etching apparatus's bias voltage to increase the etching rate of the anti-reflection coating (ARC) and light-absorption layer (LAL) while enhancing the capping layer's durability, allowing for faster repair without risking damage to the capping layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching processes are used to remove defects from EUV photomasks, then defects can be removed, but the process is time-consuming and costly
Solution Approach 1:
The patent changes the bias voltage parameter of the etching apparatus to increase the etching rate. By adjusting this physical parameter, the etching process becomes faster while still maintaining the ability to remove defects effectively, thus resolving the contradiction between defect removal effectiveness and repair time.
Solution Approach 2:
The patent implements dynamic control of the etching process by adjusting bias voltage during different stages of etching. The system dynamically modifies etching parameters to optimize both speed and precision, allowing faster repair without sacrificing defect removal effectiveness.
2Productivity
If etching rate is increased to reduce repair time, then photomask repair becomes faster, but the capping layer may be damaged
Solution Approach 1:
The patent applies local quality by making the capping layer more durable specifically at the regions where it needs to withstand increased etching rates. The etching process is localized to affect only the ARC and LAL layers, while the capping layer's enhanced durability is concentrated where it interfaces with these layers, protecting it from damage during faster etching.
Solution Approach 2:
The patent enhances the capping layer's durability beforehand through prior treatment or design modifications. This pre-strengthening acts as a cushion that protects the capping layer from potential damage during the accelerated etching process, allowing higher productivity without compromising reliability.
3Speed
If bias voltage is increased to enhance etching rate, then etching speed increases, but control precision may be reduced
Solution Approach 1:
The patent employs dynamic adjustment of bias voltage during the etching process. The system starts with higher voltage to achieve fast etching, then dynamically reduces voltage as the etching progresses to maintain precision in the final stages. This dynamic control allows the system to achieve both high speed and high precision that would be impossible with a fixed voltage setting.
Solution Approach 2:
The patent uses periodic modulation of the bias voltage during etching. By applying voltage in periodic cycles with varying amplitudes, the system achieves both high average etching speed and precise control over the etching depth and profile, resolving the contradiction between speed and precision.
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 approach significantly reduces the photomask repair time while maintaining the integrity of the capping layer, enhancing the efficiency of the photomask fabrication and repair process.
Implementation Method 1
performing a repairing operation on the photomask by the electron beam writer system with the bias voltage
Implementation Method 2
revising the etching apparatus's bias voltage to increase the etching rate of the anti-reflection coating (ARC) and light-absorption layer (LAL)
Data Source
AI summary
A method includes: providing a photomask used in extreme ultra violet (EUV) lithography; receiving information of the photomask; determining a bias voltage of an electron beam writer system according to the information; and performing a repairing operation on the photomask by the electron beam writer system with the bias voltage.