Photomask Substrate Defect Repair via Fluorine Plasma Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in photomask substrate defects during cleaning and polishing processes, which can lead to compounding defects in patterned layers, especially as feature sizes decrease, necessitating improved techniques for defect removal and substrate preparation.
Innovation Solution
A method involving the creation of alignment marks on photomask substrates using localized deposition or removal processes, followed by inspection, cataloging, and automated or semi-automated repair of pit and particle defects using techniques like gas-assisted deposition, focused ion beam etching, and atomic force microscopy nanomachining, with subsequent cleaning to ensure a defect-free surface for subsequent layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cleaning and polishing processes are used to prepare photomask substrates, then surface quality is improved, but defects are introduced during the processes
Solution Approach 1:
The patent replaces mechanical cleaning and polishing processes with a chemical etching process using fluorine-based plasma. This substitution eliminates the mechanical contact that introduces defects while achieving the desired surface preparation through chemical reactions that remove contaminants without generating mechanical defects.
Solution Approach 2:
The patent changes the fundamental parameter of the surface preparation process from mechanical action to chemical action. By using fluorine-based plasma etching, the process transitions from physical removal of material to chemical removal, fundamentally changing how surface quality is achieved without introducing mechanical defects.
2Productivity
If feature sizes are decreased to increase device density, then manufacturing capability is improved, but photomask substrate defects cause compounding defects in patterned layers
Solution Approach 1:
The patent applies preliminary action by performing surface preparation and defect removal on the photomask substrate before the actual photolithography process. The fluorine-based plasma etching is conducted in advance to eliminate potential defect sources, ensuring that when high-resolution patterning occurs, the substrate is already optimized to prevent defect propagation to the final patterned layers.
Solution Approach 2:
The patent replaces mechanical cleaning processes with chemical plasma etching to prepare the substrate surface. This substitution is critical for maintaining pattern quality at reduced feature sizes, as chemical processes introduce fewer defects than mechanical processes, thereby preventing defect compounding in the final patterned layers.
3Ease of manufacture
If conventional cleaning processes are used on photomask substrates, then surface contamination is removed, but defects remain after cleaning
Solution Approach 1:
The patent changes the cleaning process parameter from mechanical/chemical-mechanical action to pure chemical action using fluorine-based plasma. This parameter change enables effective contamination removal while avoiding the defect introduction associated with conventional mechanical cleaning methods, achieving both cleaning effectiveness and a defect-free surface.
Solution Approach 2:
The patent substitutes mechanical cleaning systems with a chemical plasma etching system. This replacement maintains the ability to remove surface contamination while eliminating the mechanical contact that causes defects, thereby achieving effective cleaning without compromising surface integrity.
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
This approach effectively reduces phase defects on photomask substrates, enabling more precise and reliable semiconductor manufacturing by ensuring a clean and defect-free surface for subsequent processing steps, thereby improving the quality of patterned layers and reducing unwanted defects.
Implementation Method 1
focused ion beam etching
Implementation Method 2
gas-assisted deposition
Data Source
AI summary
Provided is a method for reducing phase defects on many different types of semiconductor mask blanks. The method includes receiving a semiconductor mask blank substrate, creating alignment marks on the surface of the substrate, performing an inspection of the surface of the substrate to locate a plurality of surface defects, and repairing the plurality of surface defects on the surface of the substrate. A semiconductor mask is also provided that includes a repaired substrate a multilayer stack comprising a plurality of molybdenum and silicon layers, a capping layer, an absorber layer, and in some instances a photoresist layer.