Dual-Layer BJT Contact Structure for Low-Resistance Ribbon Bonding
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Solution Overview
Problem
Existing bipolar junction transistors (BJTs) face challenges in reducing power loss and increasing efficiency due to limitations in enlarging the emitter bond pad area without increasing specific area resistance, and they are not suitable for ribbon bonding over the active area.
Innovation Solution
A bipolar junction transistor design featuring a dual-layer metal structure with insulating structures isolating emitter and base contacts, allowing for ribbon bonding and enlarged emitter bond area without sacrificing active area, and incorporating columnar support pillars for mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the emitter bond pad area is enlarged to accommodate low resistance multiple bond wires or ribbon bond connection, then the package resistance is reduced, but the active area is reduced and the specific area resistance of the BJT device increases
Solution Approach 1:
The patent introduces a second metal layer above the first metal layer to create a three-dimensional metal contact structure. The second metal layer provides additional bonding area for ribbon bonds without occupying lateral space that would reduce the active area of the BJT device. This vertical dimensionality change resolves the contradiction by enabling low resistance connections while preserving the horizontal active area.
Solution Approach 2:
The patent segments the metal contact structure into multiple layers (first metal layer and second metal layer) with each layer serving specific functions. The first metal layer provides initial contact and connection, while the second metal layer provides additional bonding area and mechanical support. This segmentation allows the emitter bond pad area to be effectively enlarged through vertical stacking rather than lateral expansion.
2Loss of energy
If multiple bond wires or ribbon bond connection are used to reduce package resistance, then the power loss is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the electrical connection function with the mechanical support function into a single integrated metal layer structure. The first and second metal layers work together to provide both low resistance electrical paths and mechanical support for ribbon bonds, eliminating the need for separate support structures and reducing overall device complexity despite enabling multiple bonding options.
Solution Approach 2:
The multi-layer metal structure serves multiple functions simultaneously: it provides low resistance electrical connections, supports multiple bonding techniques (wire bonding and ribbon bonding), offers mechanical strength, and enables flexible packaging options. This multi-functionality reduces the need for additional components and simplifies the overall device design.
3Loss of energy
If ribbon bond technology is used to reduce package resistance, then the power loss is reduced, but the mechanical strength and device integrity may be compromised
Solution Approach 1:
The patent uses a composite metal layer structure where the first metal layer and second metal layer are made of conductive materials that provide both electrical conductivity and mechanical strength. The combination of multiple metal layers creates a composite structure that maintains device integrity while supporting ribbon bond connections and reducing package resistance.
Solution Approach 2:
The first metal layer serves as a foundation and support structure before the second metal layer is added. This preliminary metal layer provides mechanical cushioning and structural integrity, ensuring that the device maintains its strength and integrity even when ribbon bonds are applied to the upper second metal layer.
Data Source
Figure 1(a)~1(b)
Figure 2~3
Figure 4(a)
AI summary
A bipolar junction transistor (BJT) comprising a semiconductor region and a plurality of metal contacts, located on a top surface of the semiconductor region, where the plurality of metal contacts comprise one or more first metal contacts that are in contact with one or more emitter regions and one or more second metal contacts that are in contact with an upper surface of a body region of the semiconductor region. One or more insulating structures are located on a top surface of the semiconductor region, where the insulating structures isolate the one or more first metal contacts from the one or more second metal contacts. A metal layer is located over the insulating structures, where the metal layer is in contact with one or more first metal contacts and is isolated from the one or more second metal contacts by the insulating structures.