Phase-shift blankmask with MoSiON layer for chemical resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional phase-shift layers in photomasks have low durability and chemical resistance to cleaning solutions containing acid and basic materials, ozone water, and hot deionized water, leading to changes in optical characteristics and surface damage during repeated cleaning processes, making it difficult to manufacture reliable photomasks with precise circuit patterns.
Innovation Solution
A phase-shift mask with a multi-layer phase-shift layer structure, where the uppermost layer is formed of MoSiON and the lower layer of MoSiN, providing enhanced chemical resistance and durability, and a light-shielding film with specific composition and thickness to maintain optical density and precision during semiconductor lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional phase-shift layer (e.g., nitrogen-containing metal silicide) is used, then the phase-shift layer has certain chemical resistance to acid and basic chemicals, but it has low durability with respect to hot deionized water and ozone water
Solution Approach 1:
The patent employs a composite phase-shift layer structure consisting of a lower layer (nitrogen-containing metal silicide such as MoSiN) and an upper layer (oxygen and nitrogen-containing metal silicide such as MoSiON). This composite structure combines the chemical resistance of the nitrogen-containing layer with the water and ozone resistance of the oxygen-containing layer, achieving both acid/base chemical resistance and durability against hot deionized water and ozone water simultaneously.
2Manufacturing precision
If the phase-shift layer is made thinner to suit KrF and ArF excimer laser processes, then the manufacturing precision is improved, but the chemical resistance and durability deteriorate
Solution Approach 1:
The composite phase-shift layer structure allows each layer to be optimized for different functions. The lower nitrogen-containing layer provides chemical resistance, while the upper oxygen-containing layer provides durability against water and ozone. This enables the overall layer to be thinner while maintaining both chemical resistance and durability, as each component layer contributes its specific protective properties.
Solution Approach 2:
Different regions of the phase-shift layer are given different compositions and properties. The lower layer is optimized for chemical resistance to acids and bases, while the upper layer is optimized for resistance to water and ozone. This local differentiation of material properties allows the thin structure to maintain comprehensive protective capabilities.
3Ease of operation
If cleaning processes are repeatedly performed during manufacture and use of photomask, then the photomask is cleaned effectively, but the thickness of phase-shift layer changes and optical characteristics deteriorate
Solution Approach 1:
The composite phase-shift layer structure with nitrogen-containing lower layer and oxygen-containing upper layer provides comprehensive chemical resistance to various cleaning solutions including acids, bases, hot deionized water, and ozone water. This enables repeated cleaning processes to be performed effectively without causing changes in layer thickness or degradation of optical characteristics such as transmissivity, reflectivity, and phase shift degree.
Solution Approach 2:
The phase-shift layer is designed with enhanced chemical resistance and durability properties before the cleaning processes begin. The oxygen-containing upper layer specifically protects against hot deionized water and ozone water, while the nitrogen-containing lower layer protects against acid and base cleaners. This pre-established protective structure cushions against damage during repeated cleaning operations.
Data Source
AI summary
Provided is a phase-shift blankmask in which a phase-shift layer is formed in at least two continuous layers or a multi-layer film and an uppermost phase-shift layer included in the phase-shift layer is thinly formed to contain a small amount of oxygen (O) so as to enhance chemical resistance and durability thereof.Accordingly, a phase-shift blankmask including the phase-shift layer having enhanced chemical resistance and durability with respect to a cleaning solution containing acid and basic materials, hot deionized water, or ozone water, which is used in a cleaning process that is repeatedly performed during manufacture of a photomask, may be provided using the uppermost phase-shift layer having the enhanced chemical resistance and durability.Furthermore, degradation in the refractive index and degree of phase shift of the phase-shift layer, caused when the cleaning process is repeatedly performed may be prevented due to the uppermost phase-shift layer having the enhanced chemical resistance and durability. Accordingly, a phase-shift blankmask including a thin phase-shift layer can be provided.