Dielectric Layer Topology Profiling With Selective Radical Etching
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Solution Overview
Problem
Current methods for fabricating layer structures with specific topology profiles, such as those used in semiconductor devices, face challenges in achieving uniform etching with sufficient etch selectivity, particularly when dealing with materials like SiN films. Existing technologies like plasma etching and wet etching have limitations in terms of selectivity, reproducibility, and environmental concerns.
Innovation Solution
A method involving the deposition of a dielectric layer on a substrate with specific resistance properties to fluorine and/or chlorine radicals, followed by exposure to these radicals under controlled dry-etching conditions. This process allows for the formation of a layer structure with a target topology profile, such as side face-remaining, lateral face-remaining, or conformal profiles, by selectively removing portions of the dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If plasma etching is used, then etch rate is high and anisotropic etching is achieved, but etch selectivity between materials deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using fluorine-based chemistry (SF6, NF3, CF4 gases) instead of traditional chlorine-based plasma etching. This parameter change enables high etch rates while achieving superior selectivity between SiN films and other materials like SiO2, TiN, and TaN, resolving the contradiction between speed and precision in the etching process.
2Manufacturing precision
If wet etching is used, then etch selectivity increases and isotropic etching is achieved, but wafer-to-wafer reproducibility and uniformity deteriorate
Solution Approach 1:
The patent replaces the wet chemical etching system with a dry plasma-based etching system using fluorine radicals. This substitution eliminates the variability inherent in liquid chemical processes while maintaining high selectivity through controlled radical reactions. The plasma process provides superior wafer-to-wafer reproducibility and uniformity compared to wet etching, while preserving the desired isotropic etching characteristics.
3Manufacturing precision
If wet etching is used, then etch selectivity is achieved, but process throughput deteriorates due to drying process requirements
Solution Approach 1:
The patent substitutes wet etching with dry fluorine-based plasma etching, which eliminates the need for subsequent drying processes. The dry etching process directly produces the desired etched features without requiring additional thermal or vacuum drying steps, thereby significantly improving process throughput while maintaining high etch selectivity between different materials.
4Manufacturing precision
If wet etching is used, then etch selectivity is achieved, but environmental safety and health concerns worsen due to chemical waste
Solution Approach 1:
The patent replaces wet chemical etching with dry plasma etching using fluorine-containing gases. This substitution eliminates the generation of large volumes of hazardous liquid chemical waste that requires special handling and disposal. The dry etching process produces minimal waste in the form of volatile fluorinated hydrocarbons that can be more easily managed through standard exhaust systems, thereby improving environmental safety and health conditions while maintaining etch selectivity.
5Manufacturing precision
If separate deposition and etching chambers are used, then process control is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the deposition and etching processes into a single integrated chamber system. The fluorine-based plasma etching can be performed in the same chamber where dielectric layers are deposited, eliminating the need for separate transfer chambers and reducing overall system complexity. This integration maintains precise process control through automated sequence management while reducing capital costs and simplifying the manufacturing workflow.
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 achieves precise control over the etch rate and selectivity, enabling the formation of layer structures with desired topology profiles. This approach improves upon existing methods by enhancing throughput, reducing environmental impact, and eliminating the need for separate deposition and etching chambers.
Implementation Method 1
exposing the dielectric layer obtained in process (a) to the fluorine and/or chlorine radicals under the first dry-etching conditions, thereby removing at least a part of the portion of the dielectric layer
Data Source
AI summary
A method for fabricating a layer structure having a target topology profile in a step which has a side face and a lateral face, includes processes of: (a) depositing a dielectric layer on a preselected area of the substrate under first deposition conditions, wherein the dielectric layer has a portion whose resistance to fluorine and/or chlorine radicals under first dry-etching conditions is tuned; and (b) exposing the dielectric layer obtained in process (a) to the fluorine and/or chlorine radicals under the first dry-etching conditions, thereby removing at least a part of the portion of the dielectric layer, thereby forming a layer structure having the target topology profile on the substrate.