III-Nitride Through-Via Layout for Backside Drain Connection
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Solution Overview
Problem
Current silicon-based power semiconductor devices face limitations in cost and design flexibility, while III-N devices on silicon substrates suffer from back-gating effects and restricted terminal connections, leading to performance and reliability issues.
Innovation Solution
The integration of III-N devices with through-vias (TVs) on insulating substrates like sapphire allows for improved device performance and reduced packaging complexity by enabling multiple terminal connections on the backside, overcoming back-gating issues and reducing metal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If III-N devices are fabricated on silicon substrates to reduce cost and improve compatibility, then manufacturing cost decreases and ease of manufacture improves, but back-gating effects occur and terminal connection flexibility is restricted
Solution Approach 1:
The device structure is segmented into front-side active region and back-side terminal region, separated by through-vias. This segmentation allows the silicon substrate to serve as a mechanical support and electrical interconnection medium without causing back-gating effects on the active channel region, thus maintaining device performance while enabling cost-effective silicon substrate fabrication
Solution Approach 2:
Through-vias act as intermediary elements that electrically connect the front-side source/drain contacts to the back-side terminals. These vias provide controlled electrical pathways that isolate the active region from the substrate, eliminating back-gating effects while maintaining the cost advantages of silicon substrate fabrication
2Device complexity
If all device terminals are formed on the same side of the substrate, then device structure is simplified, but metal resistance increases and design flexibility is restricted
Solution Approach 1:
The device terminals are distributed across two dimensions - front-side terminals (gate, source, drain) and back-side terminals (source, drain). This spatial distribution reduces the metal trace lengths required for current flow, thereby reducing metal resistance and improving electrical performance while maintaining structural simplicity through the through-via interconnections
3Adaptability or versatility
If through-vias are used to extend terminals to the backside of the substrate, then terminal connection flexibility improves and metal resistance decreases, but device structure and fabrication process become more complex
Solution Approach 1:
The through-vias are formed and filled with conductive material during the epitaxial growth process or as a preliminary step before final device fabrication. This preliminary action integrates the via formation into the existing fabrication flow, reducing the need for additional complex processing steps while enabling back-side terminal connections
Data Source
AI summary
A semiconductor device comprises a III-N device including an insulating substrate. The insulating substrate includes a first side and a second side. The device further includes a III-N material structure on a first side of the insulating substrate, and a gate electrode, a source electrode, and a drain electrode on a side of the III-N material structure opposite the substrate. A backmetal layer on the second side of the insulating substrate, and a via hole is formed through the III-N material structure and the insulating substrate. A metal formed in the via-hole is electrically connected to the drain electrode on the first side of the substrate and electrically connected to the backmetal layer on the second side of the substrate.