Plasma Etching with Protective Film to Prevent Mask Metal Release
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Solution Overview
Problem
Conventional plasma etching methods using metal-containing masks result in metal contamination, leading to degraded recess shapes and potential etching stop issues due to metal release from the mask.
Innovation Solution
A plasma etching method involving a protective film formation process on a metal-containing film, followed by an etching process using the metal-containing film as a mask, with intermittent radio frequency power application for ion attraction to prevent metal release and improve recess shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a metal-containing film is used as a mask for plasma etching, then the etching process can be performed, but metal is released from the mask and adheres to the etching target film, degrading the recess shape and causing etching stop
Solution Approach 1:
A protective film is introduced as an intermediary layer between the metal-containing mask and the etching target film. This protective film prevents direct contact and adhesion between released metal and the target film, while still allowing the etching process to proceed effectively through the protective film.
Solution Approach 2:
The protective film is formed on the metal-containing mask before the plasma etching process begins. This preliminary action ensures that the mask surface is prepared in advance to prevent metal release and adhesion during the subsequent etching operation.
2Productivity
If a metal-containing film is used as a mask, then etching can proceed, but the released metal causes tapered sidewalls and critical dimension reduction
Solution Approach 1:
The protective film serves as a mediator that allows plasma etching to proceed at effective rates while preventing the harmful interaction between released metal and the etching target film, thereby maintaining critical dimension control and preventing tapered sidewall formation.
Solution Approach 2:
The harmful function of the metal-containing mask (releasing metal that adheres to the target film) is separated from its useful function (providing mask pattern). The protective film extracts and isolates the harmful metal release, allowing the mask to perform only its useful patterning function.
3Reliability
If intermittent radio frequency power is applied for ion attraction, then metal release is prevented, but the process complexity increases
Solution Approach 1:
Radio frequency power is applied in periodic intervals during the plasma etching process rather than continuously. This periodic application timing creates optimal conditions for ion attraction that prevents metal release from the mask, while allowing plasma generation to occur during other intervals.
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 prevents metal contamination and maintains the integrity of recess shapes during etching, avoiding etching stop and enhancing etching precision.
Implementation Method 1
etching an etching target film by plasma generated from a processing gas
Implementation Method 2
applying a radio frequency power for attraction of ions in the plasma
Implementation Method 3
applying a radio frequency power for attraction of ions in the plasma for a period during which the plasma is being generated from the processing gas
Data Source
AI summary
Etching stop which is caused by a metal released from a metal-containing mask can be avoided. A plasma etching method includes a protective film forming process of forming a protective film on a metal-containing film, which is formed on an etching target film and provided with a preset opening pattern, by a first processing gas; and an etching process of etching the etching target film by plasma generated from a second processing gas while using, as a mask, the metal-containing film on which the protective film is formed.