Cryogenic Etching of Laminated Silicon Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching processes for silicon-containing films in 3D stacked semiconductor manufacturing face challenges in maintaining high etch rates while suppressing side etching and achieving desirable etching profiles, particularly in forming deep holes or trenches through laminated layers with different compositions.
Innovation Solution
An etching process method involving a cryogenic temperature environment with a sulfur fluoride-containing gas and a hydrogen-containing gas, generating plasma to etch laminated films, which suppresses side etching and maintains a high etch rate by controlling the temperature of the substrate to ≤−35°C and using specific gas combinations like SF6 and H2 or SF6 and CH4.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fluorocarbon-based gas or hydrocarbon-based gas is used to increase mask selectivity, then mask selectivity is improved, but side etching increases and etching profile deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from conventional fluorocarbon-based (CF4) or hydrocarbon-based (CH4) gases to sulfur fluoride-based gases (SF6, S2F10). This parameter change fundamentally alters the etching chemistry to reduce side etching while maintaining high mask selectivity. The sulfur-containing etching species provide directional etching that minimizes lateral erosion of the mask pattern.
Solution Approach 2:
The patent employs a composite gas system combining sulfur fluoride-containing gas with hydrogen-containing gas (H2, HD, or D2). This composite approach leverages the high etch rate and vertical profile of SF6 while hydrogen terminates silicon dangling bonds to suppress side etching. The synergistic combination achieves both high mask selectivity and minimal side etching that neither gas alone can provide.
2Productivity
If high etch rate is maintained, then productivity is improved, but side etching increases
Solution Approach 1:
The patent changes the etching chemistry from carbon-based to sulfur-based etching species. Sulfur fluoride gases provide highly reactive fluorine atoms for rapid silicon etching while sulfur atoms deposit on sidewalls to form protective layers that suppress side etching. This chemical parameter change enables high vertical etch rates with minimal lateral etching, resolving the contradiction between productivity and side etching control.
Solution Approach 2:
The patent converts the potentially harmful effect of sulfur deposition into a beneficial protective mechanism. Sulfur atoms that would normally be considered contaminants actually form protective sulfide layers on the etched sidewalls, preventing polymer buildup and side etching. This transforms a potential defect into a feature that enables high-rate, high-aspect-ratio etching with excellent profile control.
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 effectively suppresses side etching, maintains a high etch rate, and achieves a desirable etching profile, improving transfer accuracy of mask patterns and preventing carbon deposition issues, suitable for forming deep features in 3D semiconductor structures.
Implementation Method 1
generating a plasma from the supplied sulfur fluoride-containing gas and hydrogen-containing gas
Implementation Method 2
etching a laminated film made up of laminated layers of silicon-containing films having different compositions with the generated plasma
Implementation Method 3
in a cryogenic temperature environment where the temperature of a substrate is controlled to be less than or equal to −35° C.
Data Source
AI summary
An etching process method is provided that includes outputting a first high frequency power from a first high frequency power supply in a cryogenic temperature environment where the temperature of a substrate is controlled to be less than or equal to −35° C., supplying a sulfur fluoride-containing gas and a hydrogen-containing gas, generating a plasma from the supplied sulfur fluoride-containing gas and hydrogen-containing gas, and etching a laminated film made up of laminated layers of silicon-containing films having different compositions with the generated plasma.