Silicon Film Etching With Non-Plasma Metal Fluoride Residue Removal
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Solution Overview
Problem
Existing substrate processing methods face challenges in effectively etching silicon-containing and carbon-containing films while managing residues generated during the etching process, particularly when using fluorine-containing gases, which can lead to residue adhesion and potential damage to the substrate.
Innovation Solution
A method involving the use of a fluorine-containing gas for etching silicon-containing films, followed by the application of a second process gas to remove residues, such as chlorine-containing gases, without generating plasma, and optionally heating the substrate to enhance residue removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorine-containing gas is used for etching silicon-containing film, then etching capability is improved, but residue generation increases
Solution Approach 1:
The patent introduces a metal-containing film as an intermediary layer between the silicon-containing film and the environment. This metal-containing film reacts with fluorine to form volatile metal fluorides that can be easily removed, preventing fluorine from directly reacting with silicon and forming difficult-to-remove silicon fluoride residues. The intermediary layer thus mediates the harmful interaction between fluorine and silicon.
Solution Approach 2:
The patent changes the chemical composition parameters by introducing specific metal elements (such as tin, aluminum, or gallium) into the etching process. These metals have different chemical reactivity with fluorine compared to silicon, forming volatile compounds at lower temperatures. This parameter change transforms the etching chemistry to favor volatile residue formation over stable residue formation.
2Speed
If fluorine-containing gas is used for etching, then etching speed is improved, but substrate damage increases
Solution Approach 1:
The metal-containing film serves as a protective intermediary that absorbs the aggressive fluorine radicals, preventing them from directly attacking and damaging the silicon substrate. The metal fluorides formed are volatile and can be removed without causing substrate damage, thus mediating between the high-speed etching requirement and substrate protection.
Solution Approach 2:
The patent converts the harmful effect of fluorine (which causes both high etching speed and substrate damage) into a beneficial effect by having it react preferentially with the metal-containing film. The fluorine's aggressive nature is redirected to form volatile metal fluorides instead of damaging the silicon substrate, thus converting a harmful interaction into a useful one.
3Object-affected harmful factors
If residue removal is performed without plasma, then substrate damage is reduced, but residue removal efficiency decreases
Solution Approach 1:
The patent changes the physical state parameters by performing residue removal in a non-plasma state (thermal desorption or chemical reaction in gas phase). This parameter change from plasma to non-plasma environment reduces the energy and aggressiveness of the removal process, preventing substrate damage while still achieving effective residue removal through thermal or chemical mechanisms.
Solution Approach 2:
The patent utilizes phase transitions of metal fluorides from solid/liquid residue state to gas phase volatile state through thermal heating or chemical reaction. This phase transition enables residue removal without requiring plasma, as the volatile metal fluorides can be easily evacuated from the chamber, achieving both low substrate damage and high removal efficiency.
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 removes residues like metal fluorides or oxides without causing further substrate damage, ensuring precise etching of features in silicon and carbon-containing films.
Implementation Method 1
etching the silicon-containing film with plasma generated from a first process gas including a fluorine-containing gas
Implementation Method 2
heating the substrate to enhance residue removal
Data Source
AI summary
In one example embodiment, a substrate processing method includes (a) providing a substrate including a silicon-containing film and a metal-containing film on the silicon-containing film, the metal-containing film including at least one opening; (b) etching the silicon-containing film with plasma generated from a first process gas including a fluorine-containing gas; and (c) removing a residue generated in the (b) by supplying a second process gas different from the first process gas, the residue including a metal and fluorine included in the metal-containing film.