RFSOI Fabrication Sequence for Oxygen Cluster and Silicide Resistance
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Solution Overview
Problem
Current semiconductor fabrication methods for radio frequency silicon-on-insulator (RFSOI) devices face issues such as high resistance due to oxygen cluster accumulation in the substrate, which affects device performance.
Innovation Solution
A method involving a first rapid thermal anneal (RTA) process after forming the source/drain regions and before silicide formation to remove oxygen clusters, followed by a second RTA process to transform the metal layer into a silicide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication process is used without RTA treatment, then process simplicity is maintained, but oxygen cluster accumulation occurs causing high resistance
Solution Approach 1:
The patent applies preliminary action by performing a first RTA process before metal layer formation to remove oxygen clusters from the semiconductor substrate. This preventive treatment eliminates the root cause of high resistance before it can develop, rather than attempting to fix resistance issues after device assembly. The RTA process heats the substrate to 400-700°C to facilitate oxygen diffusion and cluster removal, proactively addressing the resistance problem in the fabrication sequence.
2Reliability
If RTA process is added to remove oxygen clusters, then device resistance is reduced, but fabrication process time increases
Solution Approach 1:
The patent merges multiple functions into the RTA process: the first RTA removes oxygen clusters, while the second RTA simultaneously forms the silicide layer by reacting metal with silicon. This combination of cleaning and silicide formation in thermal processing steps reduces the total number of separate process steps compared to performing these functions separately with different equipment and methods.
3Reliability
If metal layer is transformed into silicide layer, then electrical conductivity is improved, but additional processing steps are required
Solution Approach 1:
The patent applies parameter changes by controlling the temperature and atmosphere parameters of the RTA process to transform the metal layer into silicide. By adjusting the thermal parameters (heating to specific temperature ranges in a controlled atmosphere), the metal undergoes in-situ reaction with silicon to form silicide compounds with superior electrical conductivity. This parameter-based transformation replaces the need for separate deposition and annealing steps.
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 reduces the overall resistance of the device by preventing oxygen cluster accumulation, thereby enhancing the performance of RFSOI devices.
Implementation Method 1
performing a first rapid thermal anneal (RTA) process to remove oxygen cluster in the substrate
Implementation Method 2
performing a second RTA process to transform the metal layer into a silicide layer
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of: forming a gate structure on a substrate; forming a source/drain region adjacent to the gate structure; performing a first cleaning process; performing a first rapid thermal anneal (RTA) process to remove oxygen cluster in the substrate; forming a metal layer on the source/drain region; and performing a second RTA process to transform the metal layer into a silicide layer.