Etch Stop Layer Protects Metal Gate from Contact Misalignment
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Solution Overview
Problem
As semiconductor devices miniaturize, contact plug misalignment can cause short circuits between metal gates and source/drain structures, leading to device failure during the fabrication process.
Innovation Solution
A manufacturing method that forms an etch stop layer with a width larger than the metal gate, which protects the metal gate from exposure during contact hole etch processes, preventing short circuits by covering the metal gate and ensuring accurate plug placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If contact plug fabrication is performed with miniaturized feature sizes, then device integration density is improved, but contact plug misalignment causes short circuit and device failure
Solution Approach 1:
An etch stop layer is formed on the metal gate structure before contact hole etching begins. This preliminary protective layer prevents the metal gate from being exposed during contact plug fabrication, even if misalignment occurs. The etch stop layer is removed after contact holes are successfully formed, completing its protective mission.
Solution Approach 2:
The etch stop layer acts as an intermediary protective element between the metal gate and the contact plug etching process. It mediates the potential harmful interaction by absorbing the etching process's impact, preventing direct contact between the contact plug and metal gate that would cause short circuits.
2Manufacturing precision
If contact plug alignment precision is increased, then short circuit prevention is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of relying solely on precise alignment, the patent applies a protective etch stop layer beforehand that cushions against potential misalignment. This approach accepts that some misalignment may occur but prevents it from causing damage, simplifying the alignment requirements while maintaining reliability.
3Reliability
If metal gate protection is enhanced, then short circuit prevention is improved, but additional process steps increase manufacturing complexity
Solution Approach 1:
The etch stop layer formation is merged with the existing gate structure fabrication process. The same etching and deposition processes used for gate formation are utilized to create the etch stop layer, eliminating the need for entirely separate process equipment or methodologies, thereby reducing the perceived complexity increase.
Solution Approach 2:
The etch stop layer serves multiple functions: it protects the metal gate during contact hole etching, defines the contact hole depth, and can be removed selectively after serving its purpose. This multi-functionality justifies the additional process step by providing multiple benefits from a single layer.
Data Source
AI summary
A manufacturing method for a semiconductor device first provides a substrate having at least a first transistor formed thereon. The first transistor includes a first conductivity type. The first transistor further includes a first metal gate and a protecting layer covering sidewalls of the first metal gate. A portion of the first metal gate is removed to form a first recess and followed by removing a portion of the protecting layer to form a second recess. Then, an etch stop layer is formed in the second recess.