FinFET Transistor Fin Back Biasing Method
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Solution Overview
Problem
FinFETs lack effective body biasing due to geometric limitations, which diminishes the body biasing effect typically seen in traditional transistor scaling, hindering the modulation of gate threshold voltage.
Innovation Solution
A method is introduced to form a FinFET with a shrunk portion as a body-biasing region, which is strategically positioned and dimensioned to apply a biasing voltage that influences the threshold voltage, allowing for effective body biasing by electrically connecting it to the source and drain regions, thereby enhancing the biasing effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FinFET geometry is used for transistor scaling, then device density and manufacturing efficiency are improved, but body biasing capability is lost
Solution Approach 1:
The fin structure is segmented into multiple regions: a channel region adjacent to the gate and a biasing region at the distal end. This segmentation allows the biasing region to be independently controlled for applying body biasing voltage, thereby restoring body biasing capability in FinFET devices while maintaining the high density benefits of the FinFET geometry.
Solution Approach 2:
A biasing electrode is introduced as an intermediary component to apply body biasing voltage to the biasing region of the fin. This electrode acts as a mediator between the external biasing circuit and the fin structure, enabling effective body biasing control in FinFET devices without compromising their geometric advantages.
2Ease of manufacture
If traditional body biasing is applied to FinFET substrate, then manufacturing simplicity is maintained, but biasing effectiveness is diminished
Solution Approach 1:
Instead of applying body biasing uniformly across the entire substrate, the invention applies biasing locally to the biasing region of the fin through a dedicated biasing electrode. This local quality approach ensures that the body biasing effect is concentrated where it is most effective—at the fin region adjacent to the channel—thereby improving threshold voltage modulation effectiveness while maintaining manufacturing simplicity.
3Length of moving object
If fin geometry is made narrow and tall, then device scaling is achieved, but body effect is virtually eliminated
Solution Approach 1:
The invention extends the fin structure in the vertical dimension by creating a biasing region at the distal end of the fin, away from the gate. This dimensional extension provides an additional degree of freedom for applying body biasing voltage, thereby restoring the body effect in narrow and tall FinFET structures where traditional substrate biasing is ineffective.
Data Source
AI summary
A method of forming a semiconductor device includes forming a fin protruding from a substrate, the fin having a channel region, a source/drain (S/D) region, and a biasing region, wherein the channel region and the biasing region sandwich the S/D region. The method further includes trimming the biasing region to reduce a height of the biasing region and forming a gate structure engaging the channel region. The method also includes forming a conductive feature electrically coupling to the biasing region.