Selective Halogen Etching of Phosphorus-Doped Silicon Films
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Solution Overview
Problem
Existing substrate-processing techniques lack an efficient method for selectively etching and removing phosphorus-doped silicon films while preserving undoped silicon films.
Innovation Solution
A substrate-processing method involving the preparation of a substrate with both undoped and phosphorus-doped silicon films, followed by the selective etching of the phosphorus-doped film using a chlorine gas, while maintaining a temperature that ensures high etching selectivity and prevents etching of the undoped film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a halogen gas is supplied to etch silicon films, then the phosphorus-doped silicon film can be removed, but the undoped silicon film may also be etched unintentionally
Solution Approach 1:
The patent applies parameter changes by optimizing the substrate temperature to a specific range (200°C to 400°C) during halogen gas etching. This temperature parameter modification creates a selective etching environment where phosphorus-doped silicon films are etched at high rates while undoped silicon films are protected, thus resolving the contradiction between achieving high etching selectivity and preventing unintentional etching of undoped regions
Solution Approach 2:
The patent utilizes local quality differences in the silicon film structure by exploiting the distinct etching characteristics between phosphorus-doped and undoped regions. The phosphorus doping creates local structural and chemical differences that enable selective etching with halogen gases at controlled temperatures, allowing the etching process to differentiate between doped and undoped areas and achieve high selectivity without damaging undoped films
2Productivity
If the substrate temperature is increased to enhance etching rate, then the etching speed increases, but the selectivity between doped and undoped films decreases
Solution Approach 1:
The patent resolves this contradiction by identifying and controlling the substrate temperature parameter within the optimal range of 200°C to 400°C. Within this temperature window, the etching rate of phosphorus-doped silicon films is maximized while maintaining high selectivity against undoped films. This parameter optimization enables simultaneous achievement of high productivity through fast etching and high manufacturing precision through selective etching
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 allows for the selective removal of phosphorus-doped silicon films, thereby protecting the underlying undoped silicon films, and achieves high etching selectivity across various silicon film types.
Implementation Method 1
supplying a halogen gas to the substrate, and, from among the undoped silicon film and the phosphorus-doped silicon film, etching and removing the phosphorus-doped silicon film selectively
Data Source
AI summary
A substrate-processing method includes: preparing a substrate including an undoped silicon film and a phosphorus-doped silicon film, at least the phosphorus-doped silicon film being exposed on a surface of the substrate; and supplying a halogen gas to the substrate, and, from among the undoped silicon film the phosphorus-doped silicon film, etching and removing the phosphorus-doped silicon film selectively.