Plasma Etching Sidewall Protection via Phosphorus Gas
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Solution Overview
Problem
Current plasma etching methods for silicon-containing films suffer from excessive lateral etching, which can lead to irregularities and reduced precision in manufacturing processes like those for DRAM and 3D-NAND devices.
Innovation Solution
The method involves using a plasma processing apparatus with a specific ratio of phosphorus-containing gases in the process gas to control the etching rate of silicon oxide and silicon nitride films, forming a protective film containing phosphorus on the sidewalls to reduce lateral etching, and adjusting the substrate temperature to enhance the protective layer's effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching methods are used for silicon-containing films, then the etching process can be completed, but excessive lateral etching occurs leading to irregularities and reduced precision
Solution Approach 1:
A protective film is introduced as an intermediary layer between the etching plasma and the sidewalls of the silicon-containing film. This protective film, formed from phosphorus-containing compounds, acts as a barrier that prevents lateral etching while allowing the main etching process to proceed on the exposed surfaces, thus resolving the contradiction between achieving etching completion and preventing harmful lateral etching
Solution Approach 2:
The invention changes the chemical composition parameters of the process gas by introducing phosphorus-containing compounds at specific concentrations (0.1-10% by flow rate). This parameter change enables the formation of a protective film on sidewalls that suppresses lateral etching, while maintaining appropriate etching rates on the main surfaces through controlled phosphorus content in the plasma environment
2Productivity
If the etching rate of silicon oxide film is increased, then manufacturing efficiency improves, but the uniformity of etching across different materials (silicon oxide and silicon nitride) deteriorates
Solution Approach 1:
The invention modifies the plasma chemistry parameters by introducing phosphorus-containing compounds, which changes the etching characteristics selectively. The phosphorus content in the plasma (controlled through gas flow rate) enables simultaneous optimization of etching speed for silicon oxide and selectivity for silicon nitride, achieving both high productivity and uniformity through precise parameter control
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 enables precise plasma etching of silicon-containing films with reduced lateral etching, improving the uniformity and aspect ratio of recesses in silicon-containing films, thus enhancing the manufacturing efficiency of devices like DRAM and 3D-NAND.
Implementation Method 1
forming a protective film containing phosphorus on the sidewalls to reduce lateral etching
Implementation Method 2
plasma etching of a silicon-containing film with reduced lateral etching
Data Source
AI summary
An etching method enables plasma etching of a silicon-containing film with reduced lateral etching. The etching method includes providing a substrate in a chamber included in a plasma processing apparatus. The substrate includes a silicon-containing film. The etching method further includes setting a flow rate proportion of a phosphorus-containing gas with respect to a total flow rate of the process gas so as to establish a predetermined ratio of an etching rate of an alternate stack of a silicon oxide film and a silicon nitride film to an etching rate of the silicon oxide film.