Photomask Blank Oxygen Concentration Adhesion
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Solution Overview
Problem
The shrinking of circuit patterns in semiconductor processes leads to poor adhesion of resist films on photomask blanks, resulting in resist pattern separation and residue generation during development, which increases defects due to the hydrophobicity caused by silylation processes like hexamethyldisilazane treatment.
Innovation Solution
A photomask blank with a silicon-containing inorganic film, such as SiO or SiON, is treated with hexamethyldisilazane to improve adhesion and reduce defects by adjusting the surface oxygen concentration to between 55-75 atomic percent, inhibiting resist pattern separation and residue generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a silylation process using hexamethyldisilazane is performed to improve adhesion, then adhesion between resist film and inorganic film is improved, but hydrophobicity increases causing resist residues and defects
Solution Approach 1:
The invention changes the surface chemical composition parameters by controlling the oxygen concentration in the silicon-containing inorganic film to 55-75 atomic percent. This parameter adjustment modifies the surface properties to achieve appropriate adhesion while reducing hydrophobicity, thereby preventing resist residues without requiring silylation processes.
Solution Approach 2:
The invention converts the potentially harmful effect of hydrophobicity into a benefit by carefully controlling the oxygen concentration parameter. By maintaining oxygen concentration within 55-75 atomic percent, the surface exhibits sufficient adhesion characteristics while avoiding excessive hydrophobicity that would cause resist residues, thus transforming a problematic surface property into an advantageous one.
2Productivity
If pattern size is shrunk to achieve higher integration, then circuit density increases, but resist pattern separation occurs due to poor adhesion
Solution Approach 1:
The invention adjusts the chemical composition parameter (oxygen concentration) of the silicon-containing inorganic film to 55-75 atomic percent. This parameter change optimizes the surface properties to maintain strong adhesion even when pattern sizes are reduced, preventing resist pattern separation while enabling higher circuit density through pattern shrinking.
3Manufacturing precision
If resist film thickness is thinned to accommodate pattern shrinking, then aspect ratio decreases improving pattern transfer, but adhesion becomes more difficult to maintain
Solution Approach 1:
The invention changes the surface chemical composition by controlling oxygen concentration in the silicon-containing inorganic film to 55-75 atomic percent. This parameter adjustment creates an optimal surface that maintains strong adhesion even when resist film thickness is reduced, enabling thin film deposition while preserving bonding strength for successful pattern transfer.
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 effectively reduces the number of defects by enhancing the adhesion between the resist film and the silicon-containing inorganic film, preventing resist pattern separation and residue formation, especially for fine patterns smaller than 50 nm.
Implementation Method 1
a surface of the silicon-containing inorganic film is subjected to a silylation process
Implementation Method 2
the oxygen concentration on a surface of the silicon-containing inorganic film is controlled
Data Source
Figure 1
Figure 2(A)~2(G)
Figure 3~4
AI summary
The present invention relates to a photomask blank obtained by forming a resist film after performing a silylation process on a silicon-containing inorganic film and provides a method for manufacturing a photomask blank having at least a silicon-containing inorganic film over a transparent substrate and a resist film on the silicon-containing inorganic film, comprising: forming the silicon-containing inorganic film such that a surface that will contact the resist film has an oxygen concentration not less than 55 atomic percent and not more than 75 atomic percent; performing a silylation process after forming the silicon-containing inorganic film; and then forming the resist film by application. The method can inhibit generation of defects due to resist residues or the like after development.