Densified Si Protection Layer for HAR Etch Mask Selectivity
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Solution Overview
Problem
High-aspect ratio etching in semiconductor manufacturing leads to mask erosion and etch deformities such as necking, bowing, and reduced B/T ratio due to ion bombardment, affecting etch resolution and accuracy.
Innovation Solution
A densified protection layer is formed using a gas mixture of hydrogen and silicon followed by argon or hydrogen treatments to reduce porosity, protecting the mask layer from erosion during energetic ion bombardment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard protection layer is deposited on the mask layer, then the mask layer is protected from erosion, but the protection layer has high porosity which reduces its protective effectiveness during ion bombardment
Solution Approach 1:
The patent applies parameter changes by modifying the protection layer's density through controlled porosity reduction. The layer transitions from a highly porous initial state to a densified state with reduced porosity, improving its protective effectiveness against ion bombardment while maintaining its composition as a deposited film layer.
Solution Approach 2:
The patent implements preliminary action by densifying the protection layer before the actual HAR etching process. This pre-treatment reduces porosity in advance, ensuring the layer is properly prepared to withstand ion bombardment during subsequent etching operations, preventing mask erosion before it occurs.
2Reliability
If the mask layer thickness is increased to prevent erosion, then mask selectivity is improved, but the aspect ratio capability is limited and etch deformities occur
Solution Approach 1:
The patent changes the protective properties of the mask system by densifying the protection layer, transforming it from a porous to a dense structure. This parameter change in the protection layer's physical state enhances mask selectivity without requiring increased mask thickness, thereby maintaining etch resolution and preventing deformities.
Solution Approach 2:
The patent creates a composite protective system consisting of the mask layer combined with a densified protection layer. This composite structure leverages the protective properties of both layers, where the densified protection layer complements the mask layer to provide enhanced erosion resistance while maintaining the original mask thickness and geometric precision.
3Productivity
If HAR etching is performed to etch high aspect ratio features, then device density is improved, but mask erosion and etch deformities occur due to ion bombardment
Solution Approach 1:
The patent performs preliminary densification of the protection layer before HAR etching to prepare the mask system for high-aspect-ratio etching. This pre-treatment ensures the protection layer has sufficient density to withstand the intense ion bombardment during HAR etching, preventing mask erosion and maintaining mask integrity throughout the etching process.
Solution Approach 2:
The densified protection layer acts as a cushioning layer that absorbs and mitigates the harmful effects of ion bombardment during HAR etching. By reducing porosity in advance, the layer creates a more robust protective barrier that cushions the mask layer against erosion, enabling successful high-aspect-ratio etching without mask degradation.
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 densified protection layer improves mask selectivity, reducing mask selectivity degradation and etch deformities, allowing for higher aspect ratios without the need for thicker hard masks.
Implementation Method 1
densifying the protection layer using argon sputtering
Implementation Method 2
exposing the protection layer to a hydrogen plasma
Data Source
AI summary
Methods for the fabrication of semiconductor devices are disclosed. A method may include depositing a mask layer on a substrate, forming a protection layer on the mask layer, and modifying the protection layer such that a porosity of the protection layer is reduced. Modifying the protection layer may include densifying the protection layer. Modifying the protection layer may include reducing the protection layer using a hydrogen plasma. The method may include etching the protection layer and the substrate. Etching may include etching, forming the protection layer, and modifying the protection layer in a predetermined number of cycles.