Phosphorus-Doped Silicon Film Removal via Selective Oxidation Etching
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Solution Overview
Problem
In semiconductor manufacturing, achieving high selectivity in removing phosphorus-doped silicon films without etching undoped silicon films is challenging due to their similar textures, leading to unintended removal of both layers during etching processes.
Innovation Solution
The method involves oxidizing the phosphorus-doped silicon film to form a silicon oxide film, which is then selectively etched using etchants with high selectivity, while the undoped silicon film remains unoxidized and intact, leveraging the difference in oxidation properties between the two films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching processing is performed to remove phosphorus-doped silicon film, then the phosphorus-doped silicon film can be removed, but the undoped silicon film is also etched together due to lack of high selectivity
Solution Approach 1:
The patent applies preliminary action by forming a silicon oxide film on the phosphorus-doped silicon film before etching. This oxidation step converts the phosphorus-doped silicon film into a different material (silicon oxide) that has high etching selectivity compared to the undoped silicon film, allowing selective removal without damaging the underlying undoped layer.
Solution Approach 2:
The patent utilizes parameter changes by exploiting the difference in oxidation properties between phosphorus-doped silicon and undoped silicon. By controlling oxidation conditions, the phosphorus-doped silicon is selectively converted to silicon oxide, which then exhibits different etching characteristics, enabling high-selectivity removal.
2Manufacturing precision
If the same substrate contains both phosphorus-doped silicon film and undoped silicon film, then high etching selectivity cannot be obtained, but selective removal is required
Solution Approach 1:
The patent introduces an intermediary substance (silicon oxide film) that mediates between the phosphorus-doped silicon film and the etching process. This intermediary layer provides the necessary selectivity difference, allowing the etching process to distinguish between the doped and undoped regions without requiring complex process parameters.
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 allows for the selective removal of the phosphorus-doped silicon film while preserving the undoped silicon film, enhancing etching selectivity and preventing unnecessary etching of the undoped layer.
Implementation Method 1
forming a silicon oxide film by oxidizing the phosphorus-doped silicon film
Implementation Method 2
selectively etching and removing the silicon oxide film from the silicon oxide film and the undoped silicon film
Data Source
AI summary
A method of removing a phosphorus-doped silicon film doped with phosphorus, includes: forming a silicon oxide film by oxidizing the phosphorus-doped silicon film in a substrate including the phosphorus-doped silicon film and an undoped silicon film which is not been doped with the phosphorus, wherein at least the phosphorus-doped silicon film is exposed to a surface of the substrate; and selectively etching and removing the silicon oxide film from the silicon oxide film and the undoped silicon film.