EUV Photomask Black Border Sidewall Passivation Without Reflectivity Loss
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Solution Overview
Problem
Traditional passivation techniques for black border sidewalls in photomasks are time-consuming, uneconomical, and degrade EUV/DUV reflectivity, leading to poor pattern fidelity and critical dimension uniformity in lithography processes.
Innovation Solution
A method and apparatus using localized passivation processes with reactive gases, lasers, or electron beams to form a passivation layer on black border sidewalls without additional patterning steps, employing plasma oxidation, nitridation, or surface quenching to protect the sidewalls from chemical reaction and diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional passivation techniques are used to protect black border sidewalls, then sidewall protection is improved, but manufacturing complexity and time consumption increase significantly
Solution Approach 1:
The patent extracts the passivation function from the complex multi-step traditional process and implements it through a single selective deposition step that deposits material only on the sidewalls using atomic layer deposition (ALD) with controlled precursor delivery, eliminating the need for multiple patterning, etching, and strip steps while maintaining sidewall protection
Solution Approach 2:
The patent employs self-aligned deposition where the sidewalls themselves serve as the template for selective material deposition. The ALD process automatically confines the deposited passivation layer to the sidewall surfaces through surface-reactive precursor chemistry, eliminating the need for separate alignment and patterning steps that would otherwise be required
2Reliability
If traditional passivation techniques are used to protect black border sidewalls, then sidewall protection is improved, but production time and cost increase
Solution Approach 1:
The patent performs preliminary passivation of the sidewalls immediately after black border formation through selective ALD deposition, protecting the sidewalls before they are exposed to subsequent processing steps. This prevents sidewall damage proactively rather than requiring corrective steps later, reducing total process time and improving productivity
Solution Approach 2:
The patent removes multiple time-consuming steps (patterning, lithography, multiple etching steps, wet/dry strip steps) from the traditional passivation process and replaces them with a single selective deposition step, dramatically reducing production time and cost while maintaining sidewall protection
3Reliability
If traditional passivation techniques are used to protect black border sidewalls, then sidewall protection is improved, but EUV/DUV reflectivity and critical dimension performance deteriorate
Solution Approach 1:
The patent applies passivation material selectively only to the sidewall regions through controlled ALD deposition, leaving the black border top surface and other areas unaffected. This localized approach protects sidewalls from chemical attack and diffusion while maintaining the optical properties (EUV/DUV reflectivity) and critical dimension performance of the patterned areas
Solution Approach 2:
The patent uses a thin passivation layer deposited by ALD as an intermediary protective barrier on the sidewalls. This layer prevents direct contact between reactive chemicals and the sidewall materials (molybdenum and silicon), blocking harmful reactions and diffusion while being thin enough to maintain optical performance and pattern fidelity
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
Enhances black border pattern fidelity, maintains EUV/DUV reflectivity, and improves critical dimension uniformity by preventing sidewall damage during photomask processing, thus ensuring reliable wafer printing performance.
Implementation Method 1
employing plasma oxidation, nitridation, or surface quenching to protect the sidewalls from chemical reaction and diffusion
Implementation Method 2
employing plasma oxidation, nitridation, or surface quenching to protect the sidewalls from chemical reaction and diffusion
Implementation Method 3
A method and apparatus using localized passivation processes with reactive gases, lasers, or electron beams
Implementation Method 4
A method and apparatus using localized passivation processes with reactive gases, lasers, or electron beams
Data Source
AI summary
The present disclosure generally relates to a method that includes providing a photomask, wherein the photomask includes a trench defined by two sidewalls which are exposed, introducing the photomask into a controlled environment, and directing (i) one or more reactive gases, (ii) a laser, (iii) one or more reactive gases and a laser, or (iv) one or more reactive gases and an electron beam, to the two sidewalls to render a passivation layer adjacent to and in contact with each sidewall. An apparatus and the photomask are also described.