High-pH Silicon Etching Composition for Dielectric Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in selectively etching silicon (Si) in the presence of other materials like metal conductors, gate materials, and dielectrics due to the shrinking feature sizes and increasing density of electronic circuitry, which can lead to device yield and performance issues.
Innovation Solution
An etching composition comprising quaternary ammonium hydroxide, an oxidizing agent, polyamine, and water, with a pH of at least 13, is used to selectively etch Si relative to materials such as SiOx and SiN, enhancing the removal of Si while minimizing the impact on other layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching compositions are used to remove Si layers, then Si etching is achieved, but other materials such as SiOx, SiN, and metal conductors are also etched, leading to device yield issues
Solution Approach 1:
The etching composition uses a high pH (at least 13) to enhance Si etching selectivity. The composition includes quaternary ammonium hydroxide as a base, oxidizing agents (such as periodic acid, potassium permanganate, or sodium chlorite), and polyamines (such as ethylenediamine, diethylenetriamine, or triethylenetetramine). These parameter changes in chemical composition and pH enable selective Si removal while protecting other materials.
Solution Approach 2:
The etching composition is a composite formulation combining multiple chemical components: quaternary ammonium hydroxide (providing high pH), oxidizing agents (enhancing Si etching rate), and polyamines (providing selectivity against SiOx and SiN). This composite approach creates synergistic effects that achieve high Si etching selectivity while minimizing damage to other materials.
2Productivity
If feature sizes are shrunk to increase device density, then device capacity is improved, but selective etching becomes more difficult due to smaller margins for error
Solution Approach 1:
The composition achieves enhanced selectivity through specific parameter combinations: pH ≥ 13, oxidizing agents at controlled concentrations, and polyamine additives. These parameters are optimized to provide sufficient selectivity margin even as feature sizes shrink, allowing high device density while maintaining manufacturing precision.
Solution Approach 2:
The polyamines in the composition act as intermediary substances that modify the etching chemistry to be more selective toward Si while being less aggressive toward SiOx, SiN, and metal conductors. This intermediary role of polyamines enables precise control over etching selectivity in high-density device manufacturing.
3Manufacturing precision
If high selectivity etching is pursued to protect other layers, then damage to other materials is minimized, but etching efficiency may be reduced
Solution Approach 1:
The composition resolves the efficiency-selectivity tradeoff by using high pH (≥13) combined with oxidizing agents. The high pH provides the driving force for efficient Si etching, while the oxidizing agents and polyamines modulate the chemistry to enhance selectivity. This parameter combination achieves both high etching efficiency and high selectivity simultaneously.
Solution Approach 2:
The inclusion of strong oxidizing agents (periodic acid, potassium permanganate, or sodium chlorite) accelerates the Si etching reaction rate while the polyamines provide selectivity control. This allows high etching efficiency to be maintained even as selectivity requirements increase for protecting other layers.
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 composition achieves a high Si/dielectric material removal rate selectivity, ensuring precise etching of Si without significantly affecting other layers, thereby improving device yield and performance.
Implementation Method 1
an etching composition that includes at least one quaternary ammonium hydroxide or a salt thereof, at least one oxidizing agent, at least one polyamine, and water
Implementation Method 2
at least one oxidizing agent
Implementation Method 3
wherein the composition has a pH of at least about 13
Data Source
AI summary
The present disclosure is directed to etching compositions that are useful for, e.g., selectively removing silicon from a semiconductor substrate as an intermediate step in a multistep semiconductor manufacturing process.