Halogen Gas Mixtures for High-Aspect-Ratio Through-Substrate Vias
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Solution Overview
Problem
Current etching processes for forming high aspect ratio through-substrate vias in semiconductor fabrication, such as TSVs, suffer from poor etch quality, low etch rates, and undesirable profile anomalies like bowing, microtrenching, and scalloping, which affect the integrity and performance of the vias.
Innovation Solution
The use of halogen gas mixtures, including chlorine-containing, fluorocarbon, and sulfur-containing gases, in a plasma chamber to generate a plasma for anisotropic etching, which minimizes lateral etching and promotes smooth sidewalls and high etch rates, addressing the limitations of Bosch and non-Bosch processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If aggressive deep etch processes are used to form high aspect ratio through-substrate vias, then etch depth and aspect ratio are improved, but etch quality and sidewall smoothness deteriorate due to profile anomalies like bowing, microtrenching, and scalloping
Solution Approach 1:
The patent applies parameter changes by modifying the etch chemistry composition (using specific halogen gas mixtures with controlled ratios of chlorine, fluorocarbon, and sulfur-containing gases) and plasma process parameters (power, pressure, gas flow rates) to achieve high aspect ratio etching while maintaining smooth sidewalls and avoiding profile anomalies
Solution Approach 2:
The patent uses composite etch chemistry comprising multiple gas components (chlorine-containing gas, fluorocarbon gas, and sulfur-containing halogen gas) that work synergistically to provide both deep etching capability and sidewall protection, resolving the contradiction between etch depth and etch quality
2Productivity
If conventional etch chemistries are used for deep etching, then etch rate may be sufficient, but mask selectivity deteriorates leading to poor etch control
Solution Approach 1:
The patent changes the chemical composition parameters of the etch gas mixture, incorporating specific halogen-containing gases that provide enhanced mask selectivity while maintaining high etch rates through optimized gas flow rates and plasma process conditions
3Length of moving object
If high aspect ratio structures are formed using traditional processes, then through-substrate connectivity is achieved, but sidewall roughness increases due to lateral etching and profile anomalies
Solution Approach 1:
The patent introduces halogen-containing gases as intermediary substances that mediate between the plasma and the substrate surface, providing sidewall passivation and protection against lateral etching, thereby maintaining smooth sidewalls during deep vertical etching
Solution Approach 2:
The patent optimizes plasma process parameters including power density, pressure, and gas composition to minimize lateral etching components and maximize vertical etching directionality, resulting in smooth sidewalls even at high aspect ratios
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 achieves high aspect ratio etching with improved etch rates, mask selectivity, and reduced sidewall roughness, enhancing the quality and reliability of through-substrate vias for 3D packaging applications.
Implementation Method 1
flowing a chlorine-containing gas, a fluorocarbon gas, and a sulfur-containing halogen gas into a plasma chamber loaded with the semiconductor substrate. The first method can also include generating a plasma from a gas chemistry including the chlorine-containing gas, the fluorocarbon gas, and the sulfur-containing halogen gas
Data Source
AI summary
A semiconductor substrate can be loaded into a plasma chamber, the semiconductor substrate having a through opening within a mask layer disposed over the semiconductor substrate. Using a plasma process, a through substrate via can be formed within the semiconductor substrate. The through substrate via can have a circular shape or an annulus shape with an inner semiconductor core. The plasma process can include exposing the through opening to a plasma chemistry formed from a gas mixture comprising boron, chlorine, fluorine, carbon, and sulfur.