Photomask Blank Chromium Oxide Interface Defect Reduction
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Solution Overview
Problem
Photomask blanks with film structures containing chromium-containing and silicon-containing films tend to develop defects over time due to oxidation and volume changes at their interface, affecting the accuracy and longevity of semiconductor pattern transfer.
Innovation Solution
A method for preparing photomask blanks with a transparent substrate, where a chromium-containing film (A) and a silicon-containing film (B) are contacted using a sputtering method, with controlled oxygen gas supply to maintain a specific intensity ratio of secondary ions, reducing defects by minimizing chromium oxidation at the interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a chromium-containing film and a silicon-containing film are deposited in contact with each other to form a photomask blank, then the manufacturing precision and pattern accuracy are improved, but defects are generated over time due to oxidation and volume changes at the interface
Solution Approach 1:
A chromium oxide layer is intentionally formed as an intermediary layer between the chromium-containing film and silicon-containing film. This mediator layer prevents direct contact and chemical reaction between chromium and silicon, eliminating the source of volume changes and defect generation while maintaining the functional integrity of the photomask blank structure
Solution Approach 2:
The chromium oxide layer is formed in advance during the film deposition process, before the interface between chromium-containing and silicon-containing films is fully established. This preliminary oxidation action prevents subsequent volume changes and defect formation by pre-stabilizing the chromium surface that will contact the silicon layer
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 method significantly reduces the generation and increase of defects over time in the photomask blanks, enhancing the accuracy and durability of the photomask for semiconductor microfabrication.
Implementation Method 1
a chromium-containing film (A) and a silicon-containing film (B) are contacted using a sputtering method
Implementation Method 2
with controlled oxygen gas supply to maintain a specific intensity ratio of secondary ions, reducing defects by minimizing chromium oxidation at the interface
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A photomask blank including a transparent substrate, and at least one film (A) containing chromium and free of silicon and at least one film (B) containing silicon, and oxygen or oxygen and nitrogen, and free of a transition metal that are contacted to each other In the blank, when an intensity of secondary ions is measured along a thickness direction of the films by a time-of-flight secondary ion mass spectrometry (TOF-SIMS), an intensity of secondary ions derived from Cr2O5 is lower than an intensity of secondary ions derived from Cr, at a position located at the interface or its vicinity of the film (A) and film (B) and having a maximum intensity of secondary ions derived from SiCrOs.