MoSiON Phase Shift Film for ArF Etching Control
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Solution Overview
Problem
In the manufacturing of semiconductor devices using half tone phase shift masks with ArF excimer laser light, the phase shift film experiences changes in transmittance and phase shift amount due to elution of metal elements and oxidation, making it difficult to detect the etching end point during defect repair, leading to potential substrate damage and reduced precision in pattern transfer.
Innovation Solution
A mask blank with a phase shift film structured as a stacked layer of a lower oxygen-free metal silicide layer and an upper metal silicide oxynitride layer, optimized to maintain a transmittance of 2-10% and a phase difference of 150-190 degrees, facilitating easier detection of the etching end point and reducing changes in optical properties during manufacturing and cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer MoSi-based phase shift film is used, then the structure is simple, but the transmittance and phase shift amount change due to metal element elution and oxidation
Solution Approach 1:
The phase shift film is divided into two distinct layers: a lower MoSi layer and an upper MoSiON layer. This segmentation allows each layer to perform specific functions - the lower layer provides phase shift while the upper layer protects against oxidation and metal element elution, thereby stabilizing transmittance and phase shift amount without requiring complex multi-material structures
Solution Approach 2:
The patent employs a composite structure combining MoSi and MoSiON materials in a layered configuration. This composite approach leverages the advantages of both materials - the phase shift capability of MoSi and the oxidation resistance of MoSiON - to achieve stable optical properties while maintaining structural simplicity
2Reliability
If plasma treatment or UV irradiation is applied to enhance ArF light fastness, then light fastness improves, but the manufacturing process becomes more complex
Solution Approach 1:
The MoSiON layer is formed during the initial film deposition process before any plasma treatment or UV irradiation steps. This preliminary formation of the protective layer provides inherent ArF light fastness without requiring additional post-processing treatments, thereby simplifying the manufacturing process while ensuring reliability
3Ease of repair
If EB defect repair is performed on black defects, then defect repair is achieved, but etching end point detection becomes difficult leading to substrate damage
Solution Approach 1:
The upper MoSiON layer exhibits distinct etching characteristics that produce visible color changes or contrast variations during EB defect repair etching. These optical changes provide clear etching end point detection signals, allowing precise control of the repair process and preventing substrate damage while maintaining effective defect repair capability
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 solution effectively reduces changes in transmittance and phase shift amount, enhances etching end point detection, and prevents substrate damage during defect repair, ensuring precise pattern transfer and improved semiconductor device manufacturing accuracy.
Implementation Method 1
a phase shift film (2) having a function to transmit an exposure light of an ArF excimer laser at a transmittance of 2% or more and less than 10%, and a function to generate a phase difference of 150 degrees or more and 190 degrees or less between the exposure light transmitted through the phase shift film (2) and the exposure light transmitted through air for a same distance as a thickness of the phase shift film (2)
Implementation Method 2
xenon difluoride (XeF2) gas is supplied to a black defect part of a light shielding film while irradiating the part with an electron beam to etch and remove the black defect part (defect repair by irradiating charged particles such as an electron beam as above is hereafter simply referred to as EB defect repair)
Data Source
AI summary
A mask blank with phase shift film where changes in transmittance and phase shift to an exposure light of an ArF excimer laser are suppressed. The film transmits light of an ArF excimer laser at a transmittance of 2% or more and less than 10% and generates a phase difference of 150 degrees or more and 190 degrees or less between the exposure light transmitted through the phase shift film and the exposure light transmitted through the air for the same distance as a thickness of the phase shift film. The film has a stacked lower layer and upper layer, the lower layer containing metal and silicon and substantially free of oxygen. The upper layer containing metal, silicon, nitrogen, and oxygen. The lower layer is thinner than the upper layer, and the ratio of metal to metal and silicon of the upper layer is less than the lower layer.