P-N-P Junction Vertical FET Integration for High Density ICs
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Solution Overview
Problem
Conventional integrated circuits face limitations in miniaturization, as they can only stack multiple device components in a single layer, typically including capacitors over passive or active devices, and CMOS transistors, which restricts the vertical alignment of field effect transistors (FETs) with other components like bipolar junction transistors (BJTs).
Innovation Solution
The integration of a P-N-P junction within an integrated circuit structure, where a p-type substrate, p-well region, and n-type barrier region are used to create a bipolar junction transistor (BJT) vertically aligned with a field effect transistor (FET), utilizing a buried insulator layer and voltage sources to induce the P-N-P junction, allowing for vertical alignment and independent operation of both transistors in a single device layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional two-dimensional circuit layout is used, then device components can be manufactured with standard processes, but the surface area occupied by each device component is large and device density is limited
Solution Approach 1:
The patent transitions from conventional two-dimensional circuit layout to a three-dimensional vertical structure by stacking the FET above the P-N-P junction with a buried insulator layer in between. This vertical stacking allows both transistor types to occupy the same footprint area while maintaining electrical isolation, effectively utilizing the third dimension (vertical space) to increase device density without increasing surface area occupation.
2Quantity of substance
If multiple device components are stacked vertically in a single layer, then device density increases, but conventional devices only allow capacitors over passive/active devices and CMOS transistors over doped well regions, limiting component compatibility
Solution Approach 1:
The buried insulator layer serves as a universal isolation mechanism that enables vertical stacking of different transistor types (FET and BJT) that would otherwise be incompatible. This single structural element allows the circuit to accommodate multiple device components with different operational requirements in the same vertical column, enhancing component compatibility and versatility while maintaining high device density.
3Area of stationary object
If FET and BJT are vertically aligned in a single device layer, then surface area is reduced and device density increases, but the structural complexity and manufacturing precision requirements increase
Solution Approach 1:
The buried insulator layer acts as an intermediary element between the FET and the P-N-P junction, providing both physical separation and alignment reference. This intermediary structure simplifies the manufacturing process by establishing a clear interface for vertical alignment, reducing the precision requirements compared to direct contact stacking, while still achieving compact vertical integration.
Data Source
AI summary
Embodiments of the disclosure provide an integrated circuit (IC) structure, including: a p-type substrate, a p-well region within the p-type substrate, and an n-type barrier region between the p-type substrate and the p-well region. The n-type barrier region physically isolates the p-type substrate from the p-well region. A field effect transistor (FET) is positioned above the p-well region, and a buried insulator layer on the upper surface of the p-well region separates the transistor from the p-well region. A first voltage source electrically coupled to the p-well region induces a P-N-P junction across the p-well region, the n-type barrier region, and the p-type substrate.