Amine Gas Pore Sealing for Selective Polysilicon Etching
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Solution Overview
Problem
Existing etching methods for semiconductor wafers with porous low-k films fail to prevent etching gases from passing through pores, leading to unintended etching of non-target films, such as the sidewall of the SiGe film during polysilicon film etching.
Innovation Solution
The method involves sequentially forming a silicon-containing film, a porous film, and a non-etching target film on the substrate, followed by supplying an amine gas to adsorb onto the porous film's walls, thereby sealing the pores and preventing etching gases from reaching the non-target film during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If etching gas is supplied to etch the silicon-containing film through the porous film, then the polysilicon film can be etched, but the etching gas passes through the pores and causes unintended etching of the non-etching target film (SiGe film)
Solution Approach 1:
An amine gas is introduced as an intermediary substance that adsorbs onto the pores of the porous low-k film, forming a protective barrier. This intermediary layer allows the etching gas to selectively etch the polysilicon film while preventing the etching gas from penetrating through the pores and damaging the SiGe film underneath.
Solution Approach 2:
The amine gas treatment creates a localized protective effect specifically at the pore interfaces of the porous film. The amine adsorbed on the pore surfaces provides selective protection only where needed (at the porous film boundaries), allowing etching to proceed in desired areas while blocking harmful etching gas penetration in critical areas.
2Object-affected harmful factors
If a dense non-porous film is used instead of a porous film to prevent etching gas penetration, then the non-target film is protected, but the low dielectric constant property is lost
Solution Approach 1:
The amine gas is supplied in advance before the main etching process to pre-adsorb and seal the pores of the low-k film. This preliminary action prepares the porous film to resist etching gas penetration while maintaining its porous structure and low dielectric constant properties throughout the subsequent etching operation.
3Productivity
If plasma processing is used to enhance etching capability, then etching speed increases, but process complexity and cost increase
Solution Approach 1:
The amine gas acts as a temporary, consumable protective layer that is easily introduced and removed. This disposable protective mechanism provides effective pore sealing without requiring complex plasma generation equipment or sophisticated process control systems, thereby reducing overall process complexity and cost.
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 effectively suppresses the etching of the non-target SiGe film while allowing the etching of the polysilicon film, reducing damage and operational complexity, and is cost-effective by eliminating the need for plasma processing and minimizing film thickness issues.
Implementation Method 1
supplying an amine gas to the substrate in which the silicon-containing film, a porous film, and a non-etching target film that is a film not to be etched but is etchable by the etching gas are sequentially formed adjacent to each other, so that amine is adsorbed onto walls of pores of the porous film
Data Source
AI summary
An etching method for etching a silicon-containing film formed in a substrate by supplying an etching gas to the substrate is provided. The method includes supplying an amine gas to the substrate, in which the silicon-containing film, a porous film, and a non-etching target film that is a film not to be etched but is etchable by the etching gas are sequentially formed adjacent to each other, so that amine is adsorbed onto walls of pores of the porous film. The method further includes supplying the etching gas for etching the silicon-containing film to the substrate in which the amine is adsorbed onto the walls of the pores of the porous film.