Alkaline Etchant Composition for Silicon-Oxide Selective Patterning
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Solution Overview
Problem
Existing etchant compositions for semiconductor devices lack high etch rates for silicon layers and sufficient etch resistance for silicon oxide layers, particularly in forming fine patterns of 50 to 500 nm, and are not suitable for structures using silicon oxide as a protective layer.
Innovation Solution
An etchant composition containing an alkaline compound, organoaluminum, and water, which maintains a high etch rate for silicon while improving the etch resistance of silicon oxide layers, ensuring excellent etch selectivity between silicon and silicon oxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an acidic etchant composition is used to etch silicon, then the etching mechanism oxidizes silicon to form silicon oxide and removes it with fluoride, but the silicon oxide layer cannot be protected and is etched away as well
Solution Approach 1:
The patent changes the fundamental chemical parameter of the etchant from acidic to alkaline composition. The alkaline etchant composition containing tetramethylammonium hydroxide and organoaluminum compounds enables selective etching of polysilicon while preserving silicon oxide layers, resolving the contradiction between etching efficiency and oxide layer protection
Solution Approach 2:
The patent creates a composite etchant system combining multiple alkaline compounds (tetramethylammonium hydroxide, organoaluminum compounds) in specific concentrations. This composite composition achieves synergistic effects that provide both high etch rate for polysilicon and selective protection for silicon oxide layers
2Productivity
If the etchant composition is optimized for high etch rate on silicon, then the etching speed increases, but the selectivity between silicon and silicon oxide layers deteriorates
Solution Approach 1:
The alkaline etchant composition exhibits local quality by reacting differently with different materials: it aggressively etches polysilicon while being inert to silicon oxide layers. This selective chemical reactivity provides both high productivity for silicon removal and high manufacturing precision for pattern definition
Solution Approach 2:
The organoaluminum compounds in the alkaline etchant act as intermediaries that enhance the etching mechanism. They facilitate the etching of polysilicon through complex chemical reactions while the alkaline environment maintains selectivity against silicon oxide, achieving both high etch rate and high selectivity
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 etchant composition achieves a high etch rate for silicon with enhanced etch resistance for silicon oxide layers, enabling precise and reliable etching of fine patterns, thereby improving the selectivity and quality of semiconductor devices.
Implementation Method 1
The wet etching process is performed by immersing an object to be removed in the etchant
Implementation Method 2
The acidic etchant composition has a mechanism of oxidizing silicon to form a silicon oxide layer and then removing the silicon oxide layer with a fluoride
Data Source
AI summary
An etchant composition contains (A) an alkaline compound, (B) an organoaluminum, and (C) water. The composition may be used in a method of forming a pattern. The composition also may be used in a method of fabricating an array substrate.