Stacked Diode Over Lateral Bipolar Transistor for RF ESD Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuits (ICs) are vulnerable to electrostatic discharge (ESD) which can affect their reliability, and in RF circuits, large voltage swings can damage p-n junctions, limiting voltage scaling and distorting harmonics in ESD protective structures.
Innovation Solution
A structure comprising a lateral bipolar transistor within a monocrystalline semiconductor, an insulator layer, and a diode in a polycrystalline semiconductor, where the diode's cathode is coupled to a well defining an emitter or collector terminal of the lateral bipolar transistor, providing enhanced ESD protection with reduced surface area and capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ESD protective structures with multiple interconnected diodes are used, then ESD protection function is provided, but capacitance increases and harmonics distortions occur
Solution Approach 1:
The patent transitions from a planar arrangement of multiple diodes to a vertical stacked configuration where a diode is positioned directly over a lateral bipolar transistor. This dimensional change reduces the horizontal footprint and minimizes parasitic capacitance while maintaining ESD protection functionality through the vertical current path.
Solution Approach 2:
The diode structure is nested over the lateral bipolar transistor, with the diode's active region positioned above the transistor's active region. This nested configuration allows the ESD protection device to occupy minimal space while the underlying transistor provides additional protection mechanisms, creating a compact multi-functional structure.
2Reliability
If ESD protective structures are implemented in RF circuits, then protection against electrostatic discharge is provided, but large voltage swings damage p-n junctions and limit voltage scaling
Solution Approach 1:
The patent modifies the electrical parameters of the ESD protection structure by using a lateral bipolar transistor with specific doping configurations and junction depths. These parameter changes enable the structure to withstand large voltage swings in RF circuits without damaging the p-n junctions, while maintaining effective ESD protection capability.
3Reliability
If multiple interconnected diodes are used for ESD protection, then ESD protection is achieved, but surface area increases
Solution Approach 1:
The patent employs a vertical stacked architecture where the diode is positioned over the lateral bipolar transistor in the vertical dimension rather than spreading multiple diodes across the horizontal plane. This dimensional reorganization dramatically reduces the surface area occupied by the ESD protection structure while maintaining its protective function.
Data Source
AI summary
Embodiments of the disclosure provide an integrated circuit (IC) structure with a diode over a lateral bipolar transistor. A structure according to the disclosure may include a lateral bipolar transistor within a monocrystalline semiconductor over a substrate. An insulator layer is over a portion of the monocrystalline semiconductor. A diode is within a polycrystalline semiconductor on the insulator layer. A cathode of the diode is coupled to a first well within the monocrystalline semiconductor. The first well defines one of an emitter terminal and a collector terminal of the lateral bipolar transistor.