Semiconductor Contact Plug with Silicide Protection
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Solution Overview
Problem
The increasing integration of semiconductor devices leads to smaller contact holes and higher aspect ratios, making it difficult to form reliable electrical contacts, resulting in potential electrical contact failures due to the penetration of etching solutions and damage to silicide layers during the wet etch process.
Innovation Solution
A semiconductor device and method that include a contact pad in a first interlayer insulating layer, a contact hole in a second interlayer insulating layer with a contact spacer, a first contact plug of doped polysilicon formed using selective epitaxial growth, and a metal silicide layer on the first contact plug, which is partially filled and surrounded by a nitride layer to prevent damage during subsequent processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the contact hole size is reduced to achieve higher integration, then the device integration density is improved, but the manufacturing precision and reliability of electrical contact deteriorate
Solution Approach 1:
The contact plug formation process is segmented into multiple stages: first forming a contact hole, then filling it with a contact plug material, and finally forming a separate metal silicide layer on top of the contact plug. This segmentation allows each step to be optimized independently, ensuring reliable electrical contact while maintaining small contact hole dimensions for high integration.
Solution Approach 2:
The metal silicide layer is formed in advance on the contact plug before subsequent wet etching processes. This preliminary action ensures that the silicide layer is already in place and protected before any etching occurs, preventing etching solution penetration and contact failures that would otherwise occur with reduced contact hole sizes.
2Productivity
If the contact hole size is reduced, then the device integration is improved, but the reliability of electrical contact deteriorates due to etching solution penetration
Solution Approach 1:
The metal silicide layer is formed on the contact plug before the wet etching process. This preliminary formation of the silicide layer ensures that it is already protective against etching solution penetration, thereby maintaining electrical contact reliability even when contact holes are small.
Solution Approach 2:
The metal silicide layer acts as a protective cushion or barrier layer that prevents the etching solution from reaching and damaging the contact plug and contact pad interface. This beforehand protection ensures that even with reduced contact hole sizes, the electrical contact remains reliable and free from etching-induced failures.
3Productivity
If the contact hole size is reduced, then the integration is improved, but the silicide layer becomes easily damaged by etching solution
Solution Approach 1:
The metal silicide layer is formed on the contact plug before the wet etching process. This preliminary formation ensures the silicide layer is already in place and structurally intact before exposure to etching solutions, preventing damage that would otherwise occur with reduced contact hole sizes.
Solution Approach 2:
The metal silicide layer serves as an intermediary protective layer between the contact plug and the etching solution. It mediates the interaction by providing a barrier that prevents the etching solution from directly contacting and damaging the contact plug, thereby maintaining silicide layer integrity even at high integration levels with small contact holes.
4Productivity
If the contact hole size is reduced, then the integration density is improved, but the alignment margin in photolithography process decreases
Solution Approach 1:
The contact structure is segmented into multiple components (contact hole, contact plug, metal silicide layer) that can be formed in separate steps. This segmentation allows the contact hole to be precisely formed with small dimensions for high integration, while the subsequent contact plug and silicide layer formation steps provide additional alignment tolerance, effectively compensating for reduced alignment margins.
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 solution effectively prevents electrical contact failures by ensuring the metal silicide layer is protected from etching solutions and maintains reliable contact connections, even in highly integrated semiconductor devices.
Implementation Method 1
a first contact plug connected to the contact pad exposed by the contact hole having the contact spacer on the internal walls thereof, the first contact plug partially filling the contact hole... forming a first contact plug connected to the contact pad exposed by the contact hole having the contact spacer formed on the internal walls thereof
Data Source
AI summary
In a semiconductor device and a method of fabricating the same, the semiconductor device includes a contact pad in a first interlayer insulating layer on a semiconductor substrate, a contact hole in a second interlayer insulating layer on the first interlayer insulating layer, selectively exposing the contact pad, a contact spacer on internal walls of the contact hole, a first contact plug connected to the contact pad exposed by the contact hole having the contact spacer on the internal walls thereof, the first contact plug partially filling the contact hole, a metal silicide layer on a surface of the first contact plug, and a second contact plug on the metal silicide layer and partially filling the remaining portion of the contact hole.