Semiconductor Etching Composition for Selective W and TiN Removal
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Solution Overview
Problem
The semiconductor industry faces challenges in selectively etching aluminum oxide (AlOx), tungsten (W), and titanium nitride (TiN) without damaging adjacent materials during the etching process, as existing methods often result in damage to gate insulating layers and semiconductor substrates, and lack sufficient selectivity over other semiconductor materials.
Innovation Solution
A composition comprising phosphoric acid, acetic acid, nitric acid, and water, with specific weight percentages, is used to selectively etch AlOx, W, and/or TiN, while minimizing etch and corrosion rates of other semiconductor materials, employing a method that includes contacting a semiconductor substrate with this composition to remove these materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional etching compositions are used, then etching of silicon dioxide is achieved, but etching of silicon nitride requires separate processing steps and selective membranes
Solution Approach 1:
The etching composition is formulated to perform multiple etching functions simultaneously - it can etch both silicon dioxide and silicon nitride materials using a single composition, eliminating the need for separate processing steps and selective membranes for different material layers
2Reliability
If conventional etching compositions are used, then etching performance is maintained, but environmental hazards and disposal costs increase
Solution Approach 1:
The composition uses alternative chemical parameters - replacing hazardous materials like HF and HNO3 with less harmful substances such as ammonium fluorosulfonate and other salts, while maintaining effective etching performance through optimized concentration ratios and pH control
Solution Approach 2:
The patent transforms potentially harmful byproducts into beneficial or neutral substances - the etching process produces ammonia and carbon dioxide as byproducts, which are far less environmentally damaging than the hazardous waste generated by conventional HF-based compositions
3Adaptability or versatility
If conventional etching compositions are used, then etching of standard materials is achieved, but etching of emerging materials like high-k dielectrics and III-V semiconductors is insufficient
Solution Approach 1:
The composition achieves universal etching capability across diverse material systems including silicon dioxide, silicon nitride, high-k dielectrics (HfO2, Ta2O5), and III-V semiconductors (GaAs, InP), providing consistent performance across emerging and traditional materials
Solution Approach 2:
The patent optimizes chemical parameters including pH control, oxidizer-to-fluoride ratios, and temperature parameters to achieve precise etching control across different material types, enabling high-quality etching of both conventional and emerging semiconductor materials
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 achieves high etch rates for AlOx, W, and TiN while maintaining low etch and corrosion rates for other semiconductor materials, thereby enhancing device yield and performance by improving etching selectivity and reducing substrate damage.
Implementation Method 1
ammonium fluorosulfonate, which etches silicon dioxide and silicon nitride
Implementation Method 2
hydrogen peroxide, which reduces metal ions and removes organic contaminants
Implementation Method 3
hydrogen peroxide, which reduces metal ions and removes organic contaminants
Data Source
AI summary
The present disclosure is directed to etching compositions that are useful, e.g., for selectively removing tungsten (W) and/or titanium nitride (TiN) from a semiconductor substrate as an intermediate step in a multistep semiconductor manufacturing process.