Process Vessel Cleaning for High-k Oxide Etch Residue Removal
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Solution Overview
Problem
Existing methods using fluorine-containing gases to etch high dielectric constant oxide films, such as hafnium oxide, face challenges due to the adherence of metal fluoride etch stops, making it difficult to remove these films effectively.
Innovation Solution
A cleaning technique involving alternating cycles of supplying chlorine-containing and oxygen-containing gases under varying pressures to etch and oxidize the oxide films, utilizing phosgene (COCl2) gas to break atomic bonds efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorine-containing gas is used to etch high dielectric constant oxide films, then etching process can be performed, but metal fluoride adheres to the film surface forming etch stops that prevent further etching
Solution Approach 1:
The patent changes the chemical composition parameter of the etching gas from fluorine-containing gas to chlorine-containing gas (specifically phosgene COCl2). This parameter change allows the etching process to proceed without forming metal fluoride etch stops, as chlorine forms volatile metal chlorides that can be completely removed, thus resolving the contradiction between etching efficiency and etching completeness.
Solution Approach 2:
The patent introduces oxygen as an intermediary substance by alternating between chlorine-containing gas supply and oxygen-containing gas supply. The oxygen serves to re-oxidize the film surface between etching cycles, preventing fluoride adhesion and enabling complete film removal. This intermediary action resolves the contradiction by facilitating continuous etching without etch stop formation.
2Productivity
If high pressure is used for gas supply, then etching rate increases, but residue formation increases
Solution Approach 1:
The patent employs periodic action by alternating between chlorine-containing gas supply (for etching) and oxygen-containing gas supply (for oxidation and residue removal). This periodic cycle allows high-pressure etching to achieve high etching rates while the subsequent oxygen supply phase removes residues, thus resolving the contradiction between etching rate and residue formation.
Solution Approach 2:
The patent maintains continuity of useful action by implementing repeated cycles of chlorine gas etching followed by oxygen gas treatment. This continuous cyclic process ensures that etching proceeds at high rates while residues are continuously removed, preventing accumulation and maintaining manufacturing precision throughout the process.
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 method enables effective removal of high dielectric constant oxide films by minimizing residue formation and enhancing etching efficiency through controlled pressure and gas supply variations.
Implementation Method 1
supplying a chlorine-containing gas to an interior of a process vessel, to which an oxide film adheres... The oxide film which adheres to the interior of the process vessel is removed by performing each of (a) to (h) one or more times
Implementation Method 2
supplying an oxygen-containing gas into the process vessel... supplying the oxygen-containing gas into the process vessel
Data Source
AI summary
There is provided a technique that includes: (a) supplying a chlorine-containing gas to an interior of a process vessel, to which an oxide film adheres, under a first pressure; (b) exhausting the interior of the process vessel; (c) supplying an oxygen-containing gas into the process vessel; (d) exhausting the interior of the process vessel; (e) supplying the chlorine-containing gas into the process vessel under a second pressure lower than the first pressure; (f) exhausting the interior of the process vessel; (g) supplying the oxygen-containing gas into the process vessel; and (h) exhausting the interior of the process vessel, wherein the oxide film which adheres to the interior of the process vessel is removed by performing each of (a) to (h) one or more times and setting a supply amount of the oxygen-containing gas in (c) different from a supply amount of the oxygen-containing gas in (g).