SiN Etching Composition for High-Selectivity Semiconductor Removal
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Solution Overview
Problem
The semiconductor industry faces challenges in selectively etching silicon nitride (SiN) in the presence of other materials like metal conductors, gate materials, and low-k dielectric layers, which affects device yield and performance due to the shrinking feature sizes and increasing density of electronic components.
Innovation Solution
An etching composition containing phosphoric acid, fluorine-containing inorganic acids or salts, nitrogen-containing compounds with alkoxysilane groups, and silane compounds is used at elevated temperatures to selectively remove SiN while minimizing the etching of other dielectric materials, such as SiOx and SiOCN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching compositions are used to remove silicon nitride, then the SiN etching can be achieved, but other materials such as metal conductors, gate materials, and low-k dielectric layers are also etched, reducing device yield and performance
Solution Approach 1:
The patent applies parameter changes by using phosphoric acid at elevated temperatures (typically 80-150°C) to dramatically increase SiN etching selectivity. The high temperature activates the phosphoric acid to selectively attack SiN while leaving other materials intact, transforming the etching process from non-selective to highly selective through temperature and chemical composition parameters
Solution Approach 2:
The etching composition uses a composite chemical system combining phosphoric acid with specific additives (fluorine-containing compounds, nitrogen-containing compounds, and silane compounds) to create a synergistic effect that achieves high SiN selectivity while protecting other materials, effectively using composite material properties to resolve the selectivity issue
2Productivity
If the feature sizes are shrunk to increase device density, then the device capacity and integration are improved, but the tolerance for etching errors decreases, making selective etching more difficult
Solution Approach 1:
By changing the chemical parameters (using phosphoric acid at high temperature), the patent achieves ultra-high etching selectivity that is necessary for processing smaller features. The temperature-dependent selectivity allows precise control over etching depth and rate, enabling accurate patterning at reduced feature sizes with minimal impact on device density
Solution Approach 2:
The phosphoric acid-based etching composition acts as an intermediary that selectively interacts with SiN while being inert to other materials. This intermediary chemical system enables precise manipulation of small features by providing a controlled, selective etching mechanism that does not compromise the integrity of surrounding structures at scaled dimensions
3Productivity
If high concentration phosphoric acid at elevated temperature is used, then the SiN removal rate increases with high selectivity, but the process complexity and temperature control requirements increase
Solution Approach 1:
The patent leverages parameter changes by using elevated temperature to accelerate the phosphoric acid etching reaction, achieving high SiN removal rates. The temperature parameter serves as a control knob that simultaneously increases both etching rate and selectivity, making the process efficient despite the added complexity of temperature management
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 SiN removal rate with selective etch rates, ensuring efficient processing and maintaining device performance by preventing the etching of other materials, thus enhancing the SiN etch selectivity and device yield.
Implementation Method 1
an etching composition containing a high concentration of phosphoric acid at an elevated temperature (e.g., 110° C. to 160° C.)
Implementation Method 2
at least one fluorine-containing inorganic acid or a salt thereof
Data Source
AI summary
The present disclosure is directed to etching compositions that are useful for, e.g., selectively removing silicon nitride from a semiconductor substrate as an intermediate step in a multistep semiconductor manufacturing process.