Vertical Bipolar Transistor Layout for Voltage-Frequency Trade-off

Solution Overview

Problem

Simultaneously manufacturing vertical bipolar transistors with high breakdown voltage and high-frequency performance on a single chip is challenging due to the trade-off between these characteristics, and existing solutions either increase process complexity or are limited to specific technologies like SOI.

Innovation Solution

The method involves forming buried collector regions with varying layouts for different transistors on the same die, allowing for tailored overlap and lateral extensions of base, emitter, and buried collector regions to achieve desired breakdown voltage and high-frequency performance characteristics without increasing process complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the distance between the buried collector and the base is made short to achieve good high-frequency performance and low collector resistance, then the high-frequency performance is improved, but the breakdown voltage decreases

Engineering Contradiction:

Improvehigh-frequency performanceVSAvoidbreakdown voltage

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The patent applies local quality by creating different lateral overlap configurations between the buried collector and emitter/base regions for different transistor types on the same die. High-frequency transistors have minimal overlap (local configuration A) to reduce capacitance and improve speed, while high-voltage transistors have larger overlap (local configuration B) to increase breakdown voltage through better electric field distribution and lower collector resistance.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If different buried collector designs are used for high breakdown voltage and high-frequency performance devices, then both device types can be manufactured, but the process complexity increases

Engineering Contradiction:

Improvedevice type varietyVSAvoidprocess complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the buried collector region into different lateral configurations (Configuration A with minimal overlap and Configuration B with larger overlap) that can be selectively applied to different transistor locations on the die. This segmentation allows simultaneous fabrication of high-frequency and high-voltage devices using a single unified process flow, avoiding the need for separate processing streams while maintaining device-specific optimization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent resolves the contradiction by introducing a lateral dimension variable (overlap extent) rather than requiring different vertical structures or additional processing steps. By varying the lateral overlap configuration of the buried collector with the emitter/base regions, the patent achieves different device characteristics within the same process framework, effectively using dimensional variation to enable device diversity without process complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Strength

If the collector-to-base breakdown voltage is increased, then the voltage breakdown performance is improved, but the high-frequency performance deteriorates

Engineering Contradiction:

Improvebreakdown voltageVSAvoidhigh-frequency performance

Core Design Contradiction:

StrengthVSSpeed

Solution Approach 1:

The patent applies local quality by creating different lateral overlap configurations between the buried collector and emitter/base regions for different transistor types on the same die. High-frequency transistors have minimal overlap (local configuration A) to reduce capacitance and improve speed, while high-voltage transistors have larger overlap (local configuration B) to increase breakdown voltage through better electric field distribution and lower collector resistance.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7495312B2Method for producing vertical bipolar transistors and integrated circuit

Publication Date: 2009.02.24 INFINEON TECHNOLOGIES AG

AI summary

A method for producing vertical bipolar transistors having different voltage breakdown and high-frequency performance characteristics on a single die comprises forming, for each of the vertical bipolar transistors, a buried collector region, and base and emitter regions above the buried collector region. The lateral extensions and locations of the base and emitter regions and of the buried collector region are, for each of the vertical bipolar transistors, selected to create an overlap between the base and emitter regions, and the buried collector region, as seen from above, wherein at least some of the overlaps are selected to be different.