Plasma Etching of Recessed Films With Sidewall Bowing Suppression
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Solution Overview
Problem
Existing etching methods face challenges in suppressing bowing, a shape abnormality where the opening dimension of a recessed portion's side wall is larger than the top portion, leading to inefficiencies in plasma etching processes.
Innovation Solution
An etching method involving the formation of a metal-containing film on the side wall of a recessed portion using a first plasma from a metal-containing gas, followed by etching with a second plasma containing hydrogen fluoride gas, with optional inclusion of a phosphorus-containing gas, while controlling the substrate or substrate support temperature to 0°C or lower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used to etch recessed portions, then etching speed is maintained, but bowing occurs where the opening dimension of the side wall becomes larger than the top portion
Solution Approach 1:
A metal-containing film is formed on the side wall of the recessed portion before the etching process begins. This preliminary film deposition prevents bowing during subsequent etching by providing a protective layer that maintains side wall integrity, allowing high-speed etching without shape distortion.
Solution Approach 2:
The metal-containing film acts as an intermediary layer between the etching plasma and the recessed portion side wall. This intermediary film protects the side wall from direct plasma attack that causes bowing, while permitting the etching process to proceed at high speed through the recessed portion.
2Manufacturing precision
If a metal-containing film is formed on the side wall before etching, then bowing is suppressed and shape precision is improved, but process complexity increases
Solution Approach 1:
The metal-containing film formation and etching processes are merged into a single integrated sequence using the same plasma processing apparatus. The film is deposited and etching is performed without breaking vacuum or transferring the substrate to another device, reducing overall process complexity despite adding a step.
Solution Approach 2:
The plasma processing apparatus is designed to perform both metal film deposition and etching functions using the same chamber and substrate handling system. This multi-functionality eliminates the need for separate deposition and etching equipment, offsetting the added process step with equipment consolidation.
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 effectively suppresses bowing, ensuring precise and controlled etching of silicon-containing films, carbon-containing films, or metal oxide films, enhancing the quality of semiconductor devices.
Implementation Method 1
forming a metal-containing film on a side wall of the recessed portion using a first plasma formed from a first processing gas
Implementation Method 2
forming a metal-containing film on a side wall of the recessed portion using a first plasma formed from a first processing gas, the first processing gas including a metal-containing gas
Implementation Method 3
etching the etching target film in the recessed portion using a second plasma formed from a second processing gas, the second processing gas including a hydrogen fluoride gas
Implementation Method 4
etching the etching target film in the recessed portion using a second plasma formed from a second processing gas, the second processing gas including a hydrogen fluoride gas
Data Source
AI summary
An etching method is provided. This method includes (a) preparing a substrate, the substrate including an etching target film and a mask including an opening disposed on the etching target film, the etching target film including a recessed portion, and the mask configured to expose the recessed portion and; (b) forming a metal-containing film on a side wall of the recessed portion using a first plasma formed from a first processing gas including a metal-containing gas, the metal-containing gas including at least one metal selected from a group comprising ruthenium, tungsten, molybdenum, and titanium; and (c) etching the etching target film in the recessed portion using a second plasma formed from a second processing gas including a hydrogen fluoride gas.