Chromium Alloy Etching via Optimized Chlorine Oxygen Plasma
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Solution Overview
Problem
Chromium and chromium alloy thin films are difficult to dry etch, with plasma etching methods like RIE being slow and resulting in residue deposition on etching chamber walls, which requires frequent cleaning, and linewidth control is challenging due to physically sputtered films.
Innovation Solution
A reactive ion etching process using a chlorine source gas and an oxygen source gas with a chlorine to oxygen atomic ratio of at least 6 to 1, or adding fluorine, to chemically etch chromium alloy films such as SiCrC, SiCrO, and SiCrN, enhancing etching rates and reducing residue deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical sputtering is used to etch chromium alloy films, then etching can be achieved, but etching rate is slow and residue deposits on chamber walls
Solution Approach 1:
The patent changes the chemical composition parameters of the etching plasma by introducing specific gas ratios (chlorine to oxygen atomic ratio of at least 6:1, or adding fluorine) to transform the etching mechanism from physical sputtering to chemical etching, thereby increasing etching rate and eliminating residue deposition
Solution Approach 2:
The patent replaces the mechanical physical sputtering process with a chemical etching process using optimized plasma chemistry, substituting ion bombardment with chemical reactions that produce volatile etch products, thus eliminating residue while maintaining high etching rates
2Manufacturing precision
If physical sputtering is used to etch chromium alloy films, then etching can be achieved, but linewidth control is difficult
Solution Approach 1:
The patent optimizes plasma chemical composition parameters (chlorine to oxygen atomic ratio of at least 6:1, addition of fluorine) to achieve chemical etching that provides both high etching rates and precise linewidth control through anisotropic etching profiles and vertical sidewall formation
3Manufacturing precision
If wet etching is used for chromium alloy films, then etching can be achieved, but dimension control is poor
Solution Approach 1:
The patent replaces wet chemical etching with plasma-based chemical etching, providing better dimension control through the directional nature of plasma etching and the ability to control etch profiles through gas composition and process parameters while maintaining high etching rates
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 process significantly improves etching rates and linewidth control for chromium alloy films, eliminating residue deposition on chamber walls and enabling efficient etching of chromium alloy films like SiCrC with a vertical sidewall profile.
Implementation Method 1
A reactive ion etching (RIE) process comprising a chlorine source gas and an oxygen source gas with an atomic ratio of chlorine to oxygen in the plasma of at least 6 to 1 is used to etch chromium alloy films
Implementation Method 2
Typically these etches utilize significant ion bombardment to physically sputter away much of the film
Implementation Method 3
Chromium alloy RIE etches are typically slow and typically deposit residue on the walls of the etching chamber walls
Data Source
AI summary
A reactive ion etching (RIE) process comprising a chlorine source gas and an oxygen source gas with an atomic ratio of chlorine to oxygen in the plasma of at least 6 to 1 is used to etch chromium alloy films such as SiCr, SiCrC, SiCrO, SiCrCO, SiCrCN, SiCrON, SiCrCON, CrO, CrN, CrON, and NiCr for example. Additionally, a fluorine source may be added to the etch chemistry.