Etching Method Using Blocking Film to Prevent Gas Permeation
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Solution Overview
Problem
In semiconductor manufacturing, etching processes often result in the unintended etching of non-target films due to permeable etching gases passing through porous films, leading to increased labor and reduced film thickness, which becomes impractical with miniaturization.
Innovation Solution
An etching method involving the formation of a blocking polyurea film within the pores of a porous SiOCN film using film-forming gases, preventing etching gases from reaching adjacent films not intended for etching, thereby isolating the silicon-containing film for precise etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry etching is used to remove the polysilicon film, then the etching speed is improved, but the etching gas passes through the porous SiOCN film and causes unintended etching of the SiGe film
Solution Approach 1:
A blocking film is introduced as an intermediary layer between the porous SiOCN film and the SiGe film. This blocking film prevents the etching gas that has passed through the porous SiOCN film from reaching and etching the SiGe film, thus resolving the harmful effect while maintaining the high etching speed benefit
Solution Approach 2:
The blocking film is formed in advance before the dry etching process. By preliminarily blocking the pores of the SiOCN film with the blocking film, the patent prevents the harmful penetration of etching gas to the SiGe film during the subsequent high-speed dry etching process
2Object-affected harmful factors
If multiple etching processes (plasma-based anisotropic etching followed by wet etching) are used to remove the polysilicon film, then the unintended etching of SiGe film is suppressed, but the process complexity and labor increase
Solution Approach 1:
The patent combines the protective function (preventing unintended etching) with the etching process by forming a blocking film that enables single-step dry etching. This merges the protection mechanism into the etching process itself, eliminating the need for separate multiple etching steps while maintaining suppression of harmful effects
Solution Approach 2:
The patent extracts the protective function from the multi-step process and implements it as a dedicated blocking film structure. This extraction allows the use of a simpler single-step dry etching process while maintaining the protective effect against unintended etching
3Length of moving object
If the thickness of the sidewall of the SiOCN film is reduced to enable miniaturization, then the device size is reduced, but the permeability of etchant increases and SiGe film may be etched
Solution Approach 1:
The blocking film serves as a mediator that compensates for the increased permeability resulting from reduced SiOCN film thickness. By introducing this intermediate blocking layer, the patent prevents etching gas from reaching the SiGe film even when the SiOCN film becomes thinner due to miniaturization requirements
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 precise etching of silicon-containing films while protecting adjacent films from etching, reducing process complexity and maintaining film thickness, and eliminates the need for atmospheric changes during wet etching, enhancing the reliability of semiconductor devices.
Implementation Method 1
forming a blocking film configured to prevent an etching gas for etching a silicon-containing film from passing through each pore of a porous film by supplying at least one film-forming gas to a substrate
Data Source
AI summary
There is provided an etching method which includes: forming a blocking film configured to prevent an etching gas for etching a silicon-containing film from passing through each pore of a porous film and prevent the etching gas from being supplied to a film not to be etched, by supplying at least one film-forming gas to a substrate in which the silicon-containing film, the porous film, and the film not to be etched are sequentially formed adjacent to each other in a lateral direction; and etching the silicon-containing film by supplying the etching gas.