Current Source Using Emitter Region as Base Isolation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing current sources are incompatible with other semiconductor logic devices due to their requirement for a deeper trench isolation structure, which contradicts contemporary semiconductor technology practices.

Innovation Solution

A current source design where the emitter region, comprising a deep-well and extending portion, surrounds and isolates the base region, allowing for electrical isolation without relying on a trench isolation structure, enabling compatibility with other semiconductor logic devices even when the trench isolation structure is fabricated to a depth less than the base region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a trench isolation structure is used to isolate the base region, then electrical isolation is achieved, but the trench depth must exceed the base region depth which increases device complexity and reduces compatibility with standard semiconductor logic devices

Engineering Contradiction:

Improveelectrical isolationVSAvoidtrench isolation structure depth

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the isolation function from the trench isolation structure and transfers it to the emitter region. The emitter region is designed to extend laterally beyond the base region boundaries, directly surrounding and isolating the base region without requiring the trench isolation structure to penetrate the full base region depth. This separates the isolation function from the depth-dependent trench structure.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The emitter region performs dual functions: it serves as the active emitter for bipolar transistor operation and simultaneously provides electrical isolation for the base region by extending laterally beyond the base region. This multi-functionality eliminates the need for a separate deep trench isolation structure, reducing device complexity while maintaining isolation reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a deeper trench isolation structure is used to isolate the base region, then electrical isolation is improved, but compatibility with other semiconductor logic devices is reduced

Engineering Contradiction:

Improveelectrical isolationVSAvoidcompatibility with semiconductor logic devices

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The isolation function is extracted from the trench isolation structure and assigned to the emitter region. The emitter region extends laterally beyond the base region to provide isolation, allowing the trench isolation structure to be shallower and compatible with standard semiconductor logic device fabrication processes.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The emitter region serves itself by extending laterally to provide the isolation function that would otherwise require a separate trench isolation structure. This self-service approach to isolation improves compatibility with standard logic devices while maintaining electrical isolation reliability.

Inventive Principle:

Principle #25Self-service

3Device complexity

If the emitter region extends laterally beyond the base region, then base region isolation is achieved without deep trench isolation, but the emitter region fabrication complexity increases

Engineering Contradiction:

Improvetrench isolation structureVSAvoidemitter region formation

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The emitter region formation process is merged with the isolation structure function. By combining the emitter region extension with the lateral surrounding of the base region, the patent eliminates the need for separate deep trench isolation fabrication steps, reducing overall device complexity while maintaining manufacturability through standard doping and patterning processes.

Inventive Principle:

Principle #5Merging (Combining)

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

This design reduces device size and facilitates integration with other semiconductor logic devices by directly isolating the base region, overcoming the limitations of relying on trench isolation, and allowing compatibility with CMOS logic devices at various process nodes.

Implementation Method 1

an emitter region of a second doping type, formed in the substrate and surrounding the base region... the emitter region comprising a deep-well portion and an extending portion

Methodology Applied

Scientific EffectDoping type isolation:

Data Source

PatentUS10950601B2Current source using emitter region as base region isolation structure

Publication Date: 2021.03.16 NEXCHIP SEMICON CO LTD

AI summary

A current source includes a substrate, a base region of a first doping type formed in the substrate, an emitter region of a second doping type formed in the substrate and surrounding the base region, a first collector region of the second doping type formed in the base region, and at least one second collector region of the second doping type formed in the base region, wherein the emitter region includes a deep-well portion and an extending portion, the deep-well portion situated beneath the base region, the extending portion laterally surrounding the base region, the extending portion joined at its bottom to the deep-well portion, the extending portion being flush at its top with a top surface of the substrate. A method of forming the current source is also disclosed.