FinFET Source/Drain Silicide Deposition Without Sidewall Etching
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Solution Overview
Problem
Existing FinFET manufacturing processes face challenges in selectively depositing a metal layer over source/drain regions without etching, which can lead to performance issues and void formation due to the consumption and oxidization of silicide regions.
Innovation Solution
A plasma enhanced chemical vapor deposition (PECVD) process is used to selectively form a silicide layer on source/drain regions by controlling the average energy of the plasmas and alternating the RF source, ensuring the sidewalls of the dielectric layer remain substantially free of the silicide layer, thus avoiding the need for etching and reducing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal layer is selectively deposited over source/drain regions using conventional PECVD process, then the silicide layer can be formed on source/drain regions, but the sidewalls of the dielectric layer become covered with silicide layer requiring etching that consumes and oxidizes the silicide regions
Solution Approach 1:
The RF source is turned on and off alternately during the PECVD process to control plasma energy periodically. This periodic action allows selective formation of silicide on source/drain regions while preventing silicide deposition on dielectric layer sidewalls, eliminating the need for etching and preserving silicide region integrity
Solution Approach 2:
The average energy of plasmas is controlled by adjusting RF source duty cycle to fall within a specific range that enables selective silicide formation. By changing the plasma energy parameter, the process selectively deposits silicide on source/drain regions with lower activation energy while avoiding deposition on dielectric layers with higher activation energy
2Manufacturing precision
If etching is used to remove silicide from dielectric sidewalls, then the silicide layer can be cleaned from unwanted areas, but the silicide regions are consumed and oxidized leading to performance issues
Solution Approach 1:
The PECVD process with controlled plasma energy is performed preliminarily to selectively deposit silicide only where needed on source/drain regions. This preliminary selective deposition eliminates the need for subsequent etching to remove excess silicide from dielectric sidewalls, preventing material loss and oxidation
Solution Approach 2:
The invention converts the potential harm of uncontrolled silicide deposition into a benefit by using the plasma energy control to achieve selective deposition. The same PECVD process that could deposit silicide everywhere is transformed into a selective deposition tool by controlling plasma energy, turning a manufacturing challenge into a precise patterning solution
3Productivity
If conventional deposition processes are used, then the metal layer can be deposited, but voids may form and the dielectric layer integrity is compromised
Solution Approach 1:
Alternating RF source on/off cycles create periodic plasma conditions that enable controlled, uniform silicide deposition. This periodic action prevents void formation by ensuring complete and uniform coverage of source/drain regions without excessive deposition on dielectric sidewalls that could lead to voids during subsequent filling processes
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 method enables efficient deposition of the silicide layer on source/drain regions without etching, maintaining the integrity of the dielectric layer and facilitating easier filling of openings with conductive materials, thereby improving the manufacturing process and reducing voids.
Implementation Method 1
A plasma enhanced chemical vapor deposition (PECVD) process is used to selectively form a silicide layer on source/drain regions
Implementation Method 2
controlling the average energy of the plasmas and alternating the RF source
Data Source
AI summary
A method of forming a semiconductor device includes forming source/drain regions on opposing sides of a gate structure, where the gate structure is over a fin and surrounded by a first dielectric layer; forming openings in the first dielectric layer to expose the source/drain regions; selectively forming silicide regions in the openings on the source/drain regions using a plasma-enhanced chemical vapor deposition (PECVD) process; and filling the openings with an electrically conductive material.