Deep Trench Isolation Etching With Fluorocarbon Byproduct Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The traditional etch process for deep trench isolation in 3D DRAM manufacturing using chlorine, hydrogen bromide, and oxygen chemistry results in byproduct buildup, leading to obstruction and reduced etch selectivity, which affects the etch profile of silicon/silicon germanium pairs.
Innovation Solution
Incorporating a fluorine-containing hydrocarbon into the etch mixture of chlorine, hydrogen bromide, and oxygen to effectively remove silicon oxide byproducts, preserving the etch profile of the superlattice structure and enhancing etch selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional chlorine, hydrogen bromide, and oxygen chemistry is used for etching deep trench isolation, then the etch process can proceed, but byproduct buildup occurs leading to obstruction and reduced etch selectivity
Solution Approach 1:
The patent modifies the etch chemistry composition by adding fluorine-containing compounds (such as CF4, C2F6, or C4F8) to the traditional Cl2/HBr/O2 mixture. This parameter change in chemical composition alters the etch reaction pathways, enabling effective removal of silicon oxide byproducts while maintaining anisotropic etching of the Si/SiGe superlattice structure, thus resolving the contradiction between etch selectivity and byproduct accumulation
Solution Approach 2:
The patent converts the harmful silicon oxide byproducts into removable species by introducing fluorine-containing etch chemistry. The fluorine reacts with silicon oxide to form volatile fluorosilicon compounds that can be easily evacuated, transforming the obstruction problem into a beneficial self-cleaning effect during the etch process, thereby maintaining high etch selectivity throughout
2Manufacturing precision
If traditional etch chemistry is used, then the process is simpler, but etch profile distortions occur due to byproduct obstruction
Solution Approach 1:
The patent employs a composite etch chemistry system that combines multiple chemical components (Cl2, HBr, O2, and fluorine-containing compounds) to achieve synergistic effects. This composite chemistry provides both the anisotropic etching capability needed for vertical profiles and the byproduct removal mechanism, delivering superior etch profile control despite the increased chemical complexity
3Productivity
If byproduct buildup occurs during etching, then the etch process continues, but hardmask opening obstruction occurs
Solution Approach 1:
The fluorine-containing etch chemistry converts potentially obstructing silicon oxide byproducts into volatile fluorosilicon species that are continuously removed during etching. This transformation maintains clear hardmask openings throughout the etch process, ensuring both high productivity and precise opening definition without requiring additional cleaning steps
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 addition of a fluorine-containing hydrocarbon improves etch selectivity and reduces silicon oxide obstruction, allowing for more precise deep trench isolation in 3D DRAM devices, facilitating higher throughput and potentially eliminating post-etch cleaning steps.
Implementation Method 1
Incorporating a fluorine-containing hydrocarbon into the etch mixture of chlorine, hydrogen bromide, and oxygen to effectively remove silicon oxide byproducts
Implementation Method 2
performing an etch process to etch an opening in the film stack on the substrate using a mixture of chlorine, hydrogen bromide, oxygen, and a fluorine-containing hydrocarbon
Data Source
AI summary
Methods of manufacturing semiconductor devices are described. A film stack on a substrate is exposed to a mixture of chlorine (Cl2), hydrogen bromide (HBr), oxygen (O2), and a fluorine-containing hydrocarbon to etch an opening in the film stack. The fluorine-containing hydrocarbon may have a general formula (I) CxHyFz wherein x is an integer in a range of from 1 to 4, y is an integer in a range of from 0 to 8, and z is an integer in a range of from 1 to 8. The film stack may additionally be exposed to etch cycles of a plasma where the plasma can be turned off periodically.