Substrate Hard Mask Removal Using Sequential Plasma Gas Cycles
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Solution Overview
Problem
Existing methods struggle to efficiently remove hard mask films from substrates while minimizing damage to insulating films, particularly when impurities are added to enhance etching resistance, leading to lower yield and inefficient subsequent processes.
Innovation Solution
A method involving sequential cycles of process gas and dissociation gas operations, where process gas reacts with the hard mask film to produce a reactant, and dissociation gas removes the reactant and protective film, using gases like CF4, SF6, Cl2, HBr, and O2, with inert gases for dissociation, at controlled temperatures and bias power application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If impurities (e.g., carbon) are added to the hard mask film to improve etching resistance and line roughness, then etching resistance is improved, but the hard mask film becomes difficult to remove after etching
Solution Approach 1:
The patent applies parameter changes by introducing a two-stage gas composition strategy. In the first stage, a process gas containing fluorine (CF4, SF6, NF3, or SiF4) reacts with the hard mask film to form volatile fluorinated compounds. In the second stage, a dissociation gas (H2, D2, or HD) is introduced to break down remaining carbon-containing compounds and oxidized impurities. This dynamic change in gas composition enables effective removal of the impurity-added hard mask film without compromising its etching resistance during the patterning process.
Solution Approach 2:
The patent uses fluorine-containing process gas as an intermediary that temporarily transforms the hard mask film into a removable state. The fluorine reacts with carbon and other impurities in the hard mask film to form volatile fluorinated compounds (e.g., CF4, COF2) that can be easily evacuated. This intermediary chemical reaction serves as a bridge between the high-etch-resistance hard mask film and the removal process, allowing both properties to be satisfied at different stages.
2Productivity
If higher temperatures and stronger density plasma are generated to remove the impurity-added hard mask film, then removal efficiency is improved, but the insulating film formed on the substrate is damaged
Solution Approach 1:
The patent applies local quality by using selective gas chemistry that targets specific materials. The process gas (fluorine-containing) selectively reacts with carbon and organic impurities in the hard mask film to form volatile compounds, while the dissociation gas (hydrogen/deuterium) selectively breaks down remaining carbon compounds. This localized chemical action spares the inorganic insulating film (silicon oxide, silicon nitride) from damage, enabling high removal efficiency without harmful effects on underlying layers.
Solution Approach 2:
The patent converts the harmful effect of oxidized impurities (which have very high boiling points and are difficult to remove) into a beneficial intermediate state. By introducing fluorine-containing process gas, the oxidized carbon impurities react to form volatile fluorinated compounds (e.g., COF2) that can be easily removed. This transforms the originally harmful high-boiling-point oxidized impurities into easily removable volatile species, achieving both complete removal and protection of the insulating film.
3Force
If strong plasma is applied to the substrate to remove the hard mask film, then removal capability is improved, but the impurity-added hard mask film remains difficult to remove and subsequent processes become less efficient
Solution Approach 1:
The patent segments the hard mask film removal process into two distinct stages with different gas compositions. The first stage uses process gas (CF4, SF6, NF3, or SiF4) to react with and volatilize carbon-containing compounds. The second stage uses dissociation gas (H2, D2, or HD) to break down and remove remaining refractory compounds and oxidized impurities. This segmentation allows each stage to be optimized for its specific function, achieving complete removal without requiring excessively strong plasma that would harm subsequent processes.
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
Efficient removal of hard mask films with added substances is achieved while minimizing damage to insulating films, maintaining high selectivity and process efficiency.
Implementation Method 1
supplying process gas to a chamber, wherein the process gas may be excited to react with a specific film formed on a substrate to produce a reactant
Implementation Method 2
supplying dissociation gas to the chamber, wherein the dissociation gas may be excited to remove the reactant from the substrate
Implementation Method 3
second gas that reacts with a surface of the film formed on the substrate to form a protective film on the surface or to etch the specific film
Data Source
AI summary
The present invention provides a substrate processing method. A substrate processing method according to an embodiment may include a first step of supplying a process gas to a chamber and exciting the process gas to react with a specific film formed on the substrate to generate a reaction product, and a second step of supplying a dissociation gas to the chamber and exciting the dissociation gas to remove the reaction product from the substrate.