Wrap-Around Source/Drain Contacts With Cut-Last Silicide Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor device fabrication processes, particularly for MOSFETs, face challenges in forming source and drain contacts that result in degraded contact resistance due to epitaxial damage and limited contact area, leading to step height issues and increased risk of shorts between contacts.
Innovation Solution
A source/drain contact 'cut last' process is implemented, which includes forming a silicide layer around the source and drain regions, using a block layer to protect the contact liner, and selectively etching to maintain wrap-around-contact silicide formation, thereby minimizing epitaxial damage and allowing for scaled contact formation without extending past the epitaxy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional source and drain contact formation process is used, then contact area is limited, but contact resistance increases and epitaxial damage occurs
Solution Approach 1:
The silicide layer is formed on the contact liner before the contact cut process. This preliminary formation of the silicide layer ensures that the low-resistance contact path is established before any potential damage from subsequent etching or cutting operations, thereby improving contact resistance while maintaining contact area
Solution Approach 2:
The contact formation process is segmented into distinct stages: forming the contact liner, annealing to create the silicide layer, and then performing the contact cut. This segmentation allows the silicide layer to be established independently before the contact geometry is finalized, resolving the contradiction between contact area and contact resistance
2Ease of manufacture
If contact cut is performed early in the process, then manufacturing is simplified, but epitaxial damage increases and contact resistance degrades
Solution Approach 1:
The silicide layer is formed preliminarily before the contact cut operation. This ensures that the beneficial low-resistance silicide contact is established before any potentially damaging cut operations, maintaining reliability while allowing process flexibility
Solution Approach 2:
Instead of cutting the contact first and then forming silicide (which would cause damage), the process is inverted: the silicide layer is formed first, then the contact cut is performed. This inversion protects the epitaxial surface from damage while maintaining ease of manufacture through the block layer protection mechanism
3Area of stationary object
If contact liner is removed completely, then contact area is maximized, but contact resistance increases due to epitaxial damage
Solution Approach 1:
The silicide layer is formed preliminarily on the contact liner before any removal operations. This ensures that even when portions of the contact liner are removed to maximize contact area, the silicide layer remains to provide low-resistance contact paths, preventing contact resistance degradation
Solution Approach 2:
The silicide layer acts as an intermediary between the contact liner and the epitaxial surface. It provides a robust, low-resistance contact path that is less susceptible to damage from liner removal, thereby enabling contact area maximization without compromising contact resistance
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 improves contact resistance and reduces the risk of shorts by maintaining the silicide contact during the contact cut process, enabling better scaling and minimizing damage to the epitaxial surfaces, thus enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
annealing to form a silicide layer around the one or more S/D regions, the silicide layer being formed at an interface between the S/D contact liner and the S/D regions
Data Source
AI summary
A technique relates to a semiconductor device. A source or drain (S/D) contact liner is formed on one or more S/D regions. Annealing is performed to form a silicide layer around the one or more S/D regions, the silicide layer being formed at an interface between the S/D contact liner and the S/D regions. A block layer is formed into a pattern over the one or more S/D regions, such that a portion of the S/D contact liner is protected by the block layer. Unprotected portions of the S/D contact liner are removed, such that the S/D contact liner protected by the block layer remains over the one or more S/D regions. The block layer and S/D contacts are formed on the S/D contact liner over the one or more S/D regions.