GaN Transistor Isolation Regions via Substrate Trenches
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Solution Overview
Problem
As semiconductor integrated circuits become more densely integrated, unwanted electrical coupling between circuit components via a common substrate can lead to performance degradation and malfunction, particularly in GaN transistors operated with different body biases or in different power domains.
Innovation Solution
The formation of isolation regions using insulating materials, including trenches and oxidized portions of the substrate, provides physical separation between GaN transistors on a common silicon substrate, reducing unwanted electrical coupling by creating a substantially continuous isolation region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If circuit components are formed closer to each other to increase integration density, then productivity and integration density are improved, but unwanted electrical coupling between components via common substrate increases causing performance degradation
Solution Approach 1:
The patent applies segmentation by dividing the common substrate into isolated regions using trenches. These trenches physically segment the substrate beneath adjacent circuit components, preventing electrical coupling while allowing components to remain in close proximity. The isolation regions created by trenches effectively partition the substrate into separate electrical domains.
Solution Approach 2:
The patent uses an intermediary approach by introducing isolation regions filled with insulating material between adjacent circuit components. These intermediary isolation regions act as mediators that prevent direct electrical coupling through the substrate while allowing the components to maintain their close spacing for high integration density.
2Reliability
If isolation regions are formed to eliminate electrical coupling between transistors, then reliability is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent merges multiple functions into the trench structure. The same trenches that provide electrical isolation also serve as anchors for forming isolation regions. By combining the trench formation and isolation region creation into a unified process flow, the patent reduces overall device complexity despite adding isolation functionality.
Solution Approach 2:
The patent applies preliminary action by forming trenches and isolation regions before completing the transistor fabrication process. This preliminary formation of isolation structures allows subsequent processing steps to proceed without additional complexity, as the isolation framework is already in place to guide further manufacturing.
3Reliability
If conventional bonding techniques are used to separate components, then electrical coupling is reduced, but parasitic inductance, resistance, and capacitance increase
Solution Approach 1:
The patent replaces conventional mechanical bonding techniques with a substrate-based isolation approach. Instead of using separate bonding structures that introduce parasitic elements, the invention uses trenches filled with insulating material directly in the substrate, eliminating the need for additional bonding components and their associated parasitic inductance, resistance, and capacitance.
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 approach effectively eliminates or decreases electrical coupling between transistors, preventing performance degradation and circuit malfunctioning, while reducing parasitic inductance, resistance, and capacitance associated with conventional bonding techniques.
Implementation Method 1
A wet etchant is introduced into the trenches, where the wet etchant etches a first opening below the first trench and a second opening below the second trench
Implementation Method 2
An oxidation process is performed to oxidize (i) surfaces of the first and second openings, and (ii) the portion of the substrate adjoining the first and second openings
Data Source
AI summary
Semiconductor structures including isolation regions and methods of forming the same are provided. A first layer is formed over a substrate, where the first layer comprises a semiconductor material. First and second trenches are etched, with each of the first and second trenches extending through the first layer and into the substrate. A wet etchant is introduced into the trenches, and the wet etchant etches a first opening below the first trench and a second opening below the second trench. Each of the first and second openings extends laterally below the first layer. The first and second openings are separated by a portion of the substrate adjoining the first and second openings. An oxidation process is performed to oxidize the portion of the substrate adjoining the first and second openings. An insulating material is deposited that fills the openings and the trenches.