EUV Photomask Stress Layer Crystallization for Warpage Correction
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Solution Overview
Problem
In the context of extreme ultraviolet (EUV) lithography, photomasks used in semiconductor manufacturing often suffer from defects and errors that can lead to defects in the devices produced, such as warpage and flatness issues, which are challenging to correct effectively.
Innovation Solution
A photomask design incorporating a stress-inducing layer with amorphous and crystalline materials, such as Al, Si, and K, and Nb, Mo, Ru, and Pb, which can be altered to correct shape deviations by converting amorphous states to crystalline states using energy beams, allowing for real-time adjustment of the photomask's shape to minimize errors during the EUV lithography process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional photomask structure is used, then the manufacturing process is simple, but shape errors such as warpage and flatness defects occur leading to device defects
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of the stress inducing layer through controlled crystallization. By changing the crystalline state (amorphous to crystalline) of specific materials in the stress inducing layer, the stress characteristics are altered, enabling precise control of photomask shape and correction of warpage and flatness errors.
Solution Approach 2:
The patent employs composite materials by creating a multi-layer stress inducing layer containing different materials (e.g., Al, Si, K and Nb, Mo, Ru, Pb) with distinct stress properties. This composite structure allows for fine-tuned stress control and precise shape correction by selectively crystallizing specific material layers to address different shape errors.
2Manufacturing precision
If the photomask shape is corrected using traditional methods, then shape errors are reduced, but the correction process is time-consuming and cannot be done in real-time
Solution Approach 1:
The patent implements dynamics by making the photomask shape correctable in real-time through controlled crystallization of the stress inducing layer. The system transitions from a static photomask structure to a dynamic one where stress characteristics can be adjusted on-demand by applying energy beams to induce crystallization at specific locations, enabling rapid shape correction without time-consuming mechanical adjustments.
Solution Approach 2:
The patent utilizes phase transitions by converting the stress inducing layer materials from amorphous to crystalline states through energy beam irradiation. This phase transition mechanism enables rapid, localized stress modification and shape correction, eliminating the need for time-consuming traditional correction methods while achieving precise real-time shape control.
3Adaptability or versatility
If amorphous material is used in the stress inducing layer, then the photomask structure is simple, but shape control capability is limited
Solution Approach 1:
The patent applies preliminary action by pre-configuring the stress inducing layer with materials that have different stress characteristics in amorphous and crystalline states. The layer is prepared in advance with the potential for stress induction, and when shape correction is needed, selective crystallization activates the predetermined stress characteristics, enabling rapid shape adjustment without complex real-time material synthesis.
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 solution enables precise correction of shape errors in photomasks, reducing warpage and improving flatness, thereby enhancing the accuracy and quality of semiconductor devices produced by EUV lithography.
Implementation Method 1
converting amorphous states to crystalline states using energy beams
Implementation Method 2
alter a stress applied to the substrate to alter a shape of the photolithographic mask
Data Source
AI summary
Provided are a photomask and a method of correcting errors thereof. The photomask includes a multilayer reflection film covering one side surface of a substrate and an energy receiving layer covering the other side surface of the substrate. The method includes determining a local correction position on a frontside surface of the photomask according to a detected error of the photomask, and locally applying an energy beam to a backside surface region of the photomask aligned with the local correction position in a thickness direction of the photomask. The invention may be applicable to structures other than photomasks that benefit from modification of surface heights or selectively applied stress.