FinFET Channel Strain via Germanium Ion Implantation
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Solution Overview
Problem
Conventional finFET fabrication techniques struggle to maintain strain in the channel region of semiconductor devices, as processes like forming fins and source/drain regions inadvertently relax the strain, affecting device performance.
Innovation Solution
A method involving forming a fin on a substrate, creating a dummy gate stack, removing portions to expose the fin, forming source/drain regions, implanting germanium ions into the channel region, and performing an annealing process to induce and maintain strain, followed by forming a gate stack to enhance device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional finFET fabrication techniques are used to form fins and source/drain regions, then the device structure is formed, but the strain in the channel region is relaxed, affecting device performance
Solution Approach 1:
The patent applies preliminary action by forming a dummy gate stack before forming the source/drain regions. This dummy gate stack serves as a protective structure that maintains the strain in the channel region during subsequent fabrication steps. The dummy gate is formed, then source/drain regions are formed around it, and finally the dummy gate is removed and replaced with the actual gate stack. This sequence ensures strain is maintained throughout the critical fabrication steps.
Solution Approach 2:
The dummy gate stack acts as an intermediary structure that protects the channel region strain during fabrication. It serves as a temporary placeholder that allows source/drain regions to be formed without directly exposing and relaxing the strained channel material. The dummy gate mediates between the need to form source/drain regions and the need to maintain channel strain.
2Ease of manufacture
If the channel region is exposed during fabrication to form source/drain regions, then the source/drain structures can be formed, but the strain in the channel region is reduced
Solution Approach 1:
The dummy gate stack is formed in advance before source/drain region formation. This preliminary structure allows source/drain regions to be formed epitaxially around the dummy gate without requiring direct exposure and manipulation of the channel region, thereby maintaining strain while enabling easy manufacture of source/drain structures.
3Reliability
If germanium ions are implanted into the channel region followed by annealing, then strain is induced and maintained in the channel region, but additional fabrication steps are required
Solution Approach 1:
The patent changes the compositional parameter of the channel region by implanting germanium ions and then performing annealing. This transforms the material composition to induce and maintain strain. The germanium implantation concentration and annealing temperature/time are optimized parameters that enable strain maintenance with acceptable additional process complexity.
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 method effectively maintains and increases strain in the channel region of finFET devices, improving their performance by enhancing the semiconductor material's properties and maintaining the desired strain levels throughout the fabrication process.
Implementation Method 1
implanting ions in the channel region of the fin
Implementation Method 2
performing an annealing process
Data Source
AI summary
A method for fabricating a semiconductor device, the method comprises forming a fin on a substrate, forming a dummy gate stack on the fin and the substrate, removing a portion of an exposed portion of the fin, forming a source/drain region on an exposed portion of the fin, forming a conductive contact on the source/drain region, removing the dummy gate stack to expose a channel region of the fin, implanting ions in the channel region of the fin, performing an annealing process, and forming a gate stack on the channel region of the fin.