HF-Phosphorus Plasma Etching for Silicon Film Mask Selectivity
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Solution Overview
Problem
Current plasma etching methods face challenges in achieving high selectivity of silicon-containing films over masks, leading to inefficiencies in manufacturing processes such as those for DRAM and 3D-NAND devices.
Innovation Solution
An etching method utilizing a process gas containing hydrogen fluoride and a phosphorus-containing gas, along with optional halogen and carbon-containing gases, to enhance the selectivity of silicon-containing films during plasma etching by generating chemical species that effectively etch the film while protecting the mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional process gases are used for plasma etching, then the etching process can proceed, but the selectivity of silicon-containing film to mask deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the process gas by introducing hydrogen fluoride gas and phosphorus-containing gas. This parameter change transforms the plasma chemistry to generate etching species that selectively react with silicon-containing films while being inhibited by phosphorus-based protective layers on masks, thereby resolving the selectivity problem without sacrificing etching efficiency
Solution Approach 2:
The patent creates a composite process environment by combining hydrogen fluoride gas with phosphorus-containing gas. This composite gas mixture produces synergistic effects where hydrogen fluoride provides the etching capability for silicon-containing films while phosphorus-containing gas forms protective species on mask surfaces, achieving both high selectivity and maintained productivity
2Productivity
If etching rate is increased to improve productivity, then manufacturing efficiency improves, but mask etching increases reducing selectivity
Solution Approach 1:
The phosphorus-containing gas acts as an intermediary that mediates between the etching process and the mask. It forms a protective phosphorus-based layer on the mask surface that prevents direct contact between aggressive etching species and the mask material, allowing high etching rates on silicon-containing films while protecting the mask from etching
Solution Approach 2:
The patent converts the potentially harmful effect of high-energy plasma species that could etch the mask into a beneficial protective mechanism. The phosphorus-containing gas reacts with these species to form protective phosphorus layers on the mask, transforming what would be mask damage into a self-protecting mechanism that enables high-speed etching with maintained selectivity
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
The method improves the selectivity of silicon-containing films to masks, allowing for higher etching rates and reduced mask etching, thereby enhancing the manufacturing efficiency of devices with complex structures.
Implementation Method 1
etching the silicon-containing film with a chemical species in plasma generated from a process gas in the chamber
Implementation Method 2
etching the silicon-containing film with a chemical species in plasma generated from a process gas containing a hydrogen fluoride gas and a phosphorus-containing gas
Data Source
AI summary
An etching method includes (a) providing a substrate in a chamber in a plasma processing apparatus. The substrate includes a silicon-containing film. The etching method further includes (b) etching the silicon-containing film with a chemical species in plasma generated from a process gas in the chamber. The process gas contains a hydrogen fluoride gas and a phosphorus-containing gas.