Etching Method Using Fluorine Gas and Ammonia Plasma
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Solution Overview
Problem
Existing atomic layer etching (ALE) methods face challenges in suppressing deposition of reaction byproducts within the etching chamber and reducing ionic damage to objects during the etching process, particularly when using CF-based gases like C4F8, which leads to reduced throughput and damage to the object.
Innovation Solution
An etching method involving a modification process using a fluorine-containing gas like ClF3 to form a modified layer on a silicon oxide film, followed by a removal process with ammonia-containing plasma, alternately repeated multiple times, which reduces deposition inside the chamber and minimizes ionic damage by using thermal treatment instead of plasma-assisted etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CF-based gas (C4F8) is used for modification process in ALE method, then etching of silicon oxide film is achieved, but deposition of reaction byproducts attaches onto inside of chamber
Solution Approach 1:
The patent extracts the harmful deposition-forming component (CF-based gas) from the modification process and replaces it with a fluorine-containing gas (ClF3, SF6, NF3) that does not produce chamber deposition, while maintaining the etching functionality through the subsequent ammonia plasma removal process
Solution Approach 2:
The patent converts the previously harmful CF-based gas into a beneficial fluorine source (ClF3, SF6, NF3) that provides fluorine atoms for modification without creating deposition problems, thereby turning a harmful factor into a beneficial one
2Productivity
If plasma of CF-based gas is used for removal process in ALE method, then modified layer is removed from object, but ionic damage is inflicted on object
Solution Approach 1:
The patent changes the chemical composition parameter of the removal process gas from CF-based to ammonia-based (NH3), which fundamentally alters the interaction mechanism from ion bombardment damage to gentle chemical reaction, enabling modified layer removal without ionic damage
Solution Approach 2:
The patent replaces the mechanical ion bombardment mechanism (CF-based plasma) with a chemical reaction mechanism (ammonia plasma), substituting physical removal with chemical transformation and removal
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 suppresses chamber deposition and reduces ionic damage, improving process throughput and etching uniformity while maintaining low variation in etching amounts, thus enhancing the overall efficiency and precision of the etching process.
Implementation Method 1
a modified layer is formed on a surface of a silicon oxide film by supplying a fluorine containing gas to an object having the silicon oxide film
Implementation Method 2
the modified layer is removed from the object by exposing the object having the modified layer formed thereon to plasma of an ammonia containing gas
Data Source
AI summary
The etching method includes a modification process and a removal process. In the modification process, a fluorine containing gas is supplied to an object having a silicon oxide film, so that a modification layer is formed on the surface of the silicon oxide film. In the removal process, the object, on which the modification layer has been formed, is exposed to plasma of a gas that contains ammonia, so that the modification layer is removed from the object. In addition, the modification process and the removal process are alternately repeated a plurality of times.