Localized Etch Stop Layer for Plasma Damage Mitigation
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Solution Overview
Problem
Semiconductor plasma processing techniques, such as dry etching, often cause damage to underlying material layers, leading to uncontrolled variations in device electrical performance and yield loss due to aggressive ion bombardment during contact hole formation in advanced structures like FinFET devices and 3D NAND architectures.
Innovation Solution
A method involving the formation of localized metal-based or nitride etch stop layers to protect sensitive semiconductor regions during plasma etching, where these layers are selectively deposited and later removed using gentle wet cleaning processes to prevent damage, ensuring the integrity of epitaxial regions and contact areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry etch process is used to open contact holes, then contact holes can be opened efficiently, but damage occurs to the underlying material layers due to aggressive ion bombardment
Solution Approach 1:
A protective layer is formed over the underlying material layers before the dry etch process. This preliminary protective action prevents plasma damage during contact hole opening while maintaining etching efficiency. The protective layer is subsequently removed after serving its protective function.
Solution Approach 2:
The protective layer acts as an intermediary between the plasma etch process and the underlying material. It absorbs the harmful ion bombardment while allowing the etch process to proceed, thereby mediating the conflict between etching efficiency and material protection.
2Object-affected harmful factors
If protective layer is formed before plasma etching, then underlying material is protected from plasma damage, but additional process steps are required to form and remove the protective layer
Solution Approach 1:
The protective layer serves multiple functions: it protects underlying materials during plasma etching, provides a removal reference plane, and can be integrated with existing process flows. This multi-functionality justifies the additional process steps by delivering multiple benefits from a single layer.
Solution Approach 2:
The protective layer is designed with specific material properties that enable selective removal after serving its protective function. By controlling the layer composition and thickness, the process adds minimal complexity while achieving effective protection and subsequent clean removal.
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 effectively minimizes plasma damage to semiconductor regions, maintaining the integrity of epitaxial layers and improving electrical performance and yield by using sacrificial etch stop layers that protect against aggressive plasma etching processes.
Implementation Method 1
etching the nitride etch stop layer with a plasma etch process to expose a surface of the metal based etch stop layer
Implementation Method 2
a dry etch process such as reactive Ion etching (RIE) may be used to open contacts... the dry etch process possesses a plasma source that generates a sea of ions that accelerate in a manner that causes ion bombardment against sensitive device layers
Implementation Method 3
removing the metal based etch stop layer using an etching process that selectively removes the metal based etch stop layer
Data Source
AI summary
In one embodiment, a method includes providing a substrate comprising a source/drain contact region and a dummy gate, forming a first etch stop layer aligned to the source/drain contact region, where the first etch stop layer does not cover the dummy gate. The method may include forming a second etch stop layer over the first etch stop layer, the second etch stop layer covering the first etch stop layer and the dummy gate. The method may include converting the dummy gate to a metal gate. The method may include removing the second etch stop layer using a plasma etching process. The method may include removing the first etch stop layer.