SOI Transistor Butted Body Tie for Floating Body Suppression
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Solution Overview
Problem
Floating body silicon-on-insulator (SOI) transistors face limitations in operating voltage and power due to accumulated hot carriers, leading to reduced electrical potential and increased complexity in device modeling. Conventional body tied devices, such as H-gate and T-gate structures, become less effective for large transistor widths due to high resistance and increased parasitic capacitance.
Innovation Solution
The introduction of a butted body tie structure in semiconductor devices, which includes a non-conductive isolation region, a body contact region, and a body tab, effectively ties the body region to the source region, reducing floating body effects and enhancing voltage and power handling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional body tied devices (H-gate, T-gate) are used for large transistor widths, then voltage and power handling capabilities are improved, but resistance increases and parasitic capacitance increases reducing effectiveness
Solution Approach 1:
The body tie structure is segmented into multiple separate body contact regions distributed across the transistor width, rather than a single continuous body tie. This segmentation reduces the total parasitic capacitance while maintaining effective body potential control across wide transistor structures, resolving the contradiction between power handling capability and parasitic capacitance reduction.
2Reliability
If body ties are added to suppress floating body effects, then voltage capability is improved, but on state conduction performance is degraded
Solution Approach 1:
Body contacts are strategically positioned only in specific local regions where floating body effects are most problematic, rather than providing continuous body tying across the entire transistor. This localized approach suppresses floating body effects in critical areas while minimizing the impact on channel conduction performance, resolving the contradiction between voltage capability and on-state conduction.
3Stability of the object's composition
If conventional body tie structures are used, then floating body effects are suppressed, but device complexity increases due to high resistance and parasitic capacitance
Solution Approach 1:
The body tie structure is divided into multiple discrete body contact regions, which simplifies the electrical model by reducing the number of parasitic capacitance elements compared to a continuous body tie. This segmentation maintains floating body effect suppression while reducing device modeling complexity, directly addressing the contradiction between stability and complexity.
Data Source
AI summary
Systems, methods, and apparatus for an improved body tie construction are described. The improved body tie construction is configured to have a lower resistance body tie exists when the transistor is “off” (Vg approximately 0 volts). When the transistor is “on” (Vg>Vt), the resistance to the body tie is much higher, reducing the loss of performance associated with presence of body tie. Space efficient Body tie constructions adapted for cascode configurations are also described.