Localized Insulated Block in Bulk Substrate for Circuit Isolation
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Solution Overview
Problem
Conventional semiconductor devices face challenges in fabricating integrated circuits that require different electrical characteristics on the same substrate, as they typically need either a bulk or isolated substrate, limiting the ability to co-fabricate circuits with varying requirements on a single substrate.
Innovation Solution
A semiconductor device with a localized insulated block in a bulk substrate is created by forming an isolated block using trenches and an insulating layer, allowing for the fabrication of integrated circuits with different characteristics on the same substrate, where the isolated block is electrically isolated from the bulk substrate using a combination of trenches and insulating materials like oxide or nitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bulk substrate is used for fabricating integrated circuits, then the substrate provides good mechanical strength and thermal conductivity, but all circuits on the substrate share the same electrical characteristics and cannot be electrically isolated
Solution Approach 1:
The substrate is segmented into isolated blocks surrounded by trenches filled with insulating material. This segmentation creates electrically isolated regions that can host circuits with different electrical characteristics, while the bulk substrate maintains its mechanical strength and thermal conductivity. The trenches act as boundaries that divide the continuous substrate into discrete functional zones.
Solution Approach 2:
Different regions of the substrate are given different local qualities through the introduction of insulating trenches. The isolated blocks have different electrical characteristics from the bulk substrate, allowing co-fabrication of circuits requiring different electrical properties. The insulating material provides localized electrical isolation without affecting the overall substrate quality.
2Adaptability or versatility
If a silicon-on-insulator substrate is used to provide electrical isolation, then circuits can be electrically isolated, but the substrate structure becomes more complex and manufacturing steps increase
Solution Approach 1:
The insulating trenches are formed preliminarily before circuit fabrication. By pre-establishing the isolated blocks and their insulating boundaries, subsequent circuit fabrication steps can proceed independently in each isolated region. This preliminary structuring simplifies the overall manufacturing process by separating concerns early in the fabrication sequence.
Solution Approach 2:
The electrical isolation function is extracted from the bulk substrate by introducing separate insulating trenches. Instead of requiring a complete silicon-on-insulator structure, only the necessary trench regions are removed and filled with insulating material, taking out the isolation function where needed while preserving the bulk substrate elsewhere.
3Productivity
If different types of integrated circuits are fabricated on the same substrate, then production efficiency increases, but electrical interference between circuits with different characteristics occurs
Solution Approach 1:
Circuits with different electrical characteristics are segmented into separate isolated blocks on the same substrate. The trenches surrounding each block prevent electrical interference between adjacent circuits, allowing high-density co-fabrication of diverse circuit types without cross-talk or interference issues.
Solution Approach 2:
Insulating material is introduced as an intermediary between different circuit blocks. This intermediary substance fills the trenches and provides electrical isolation, enabling circuits with different voltage levels and electrical characteristics to coexist on the same substrate without interfering with each other.
Data Source
AI summary
One or more trenches can be formed around a first portion of a semiconductor substrate, and an insulating layer can be formed under the first portion of the semiconductor substrate. The one or more trenches and the insulating layer electrically isolate the first portion of the substrate from a second portion of the substrate. The insulating layer can be formed by forming a buried layer in the substrate, such as a silicon germanium layer in a silicon substrate. One or more first trenches through the substrate to the buried layer can be formed, and open spaces can be formed in the buried layer (such as by using an etch selective to silicon germanium over silicon). The one or more first trenches and the open spaces can optionally be filled with insulative material(s). One or more second trenches can be formed and filled to isolate the first portion of the substrate.