Segmented Bond Pad Reduces Parasitic Capacitance
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Solution Overview
Problem
In semiconductor devices, particularly RF power transistors, parasitic capacitance contributed by bond pads hinders RF signal gain and increases signal distortion, as traditional methods to reduce capacitance compromise wire bond flexibility and mechanical integrity.
Innovation Solution
A bond pad region with a reduced effective area, featuring a small bus bar bond pad and electrically isolated metal tiles, which only contribute to parasitic capacitance when connected, maintains wire bond flexibility and reduces overall parasitic capacitance by 50% or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the bus bar area is reduced to decrease parasitic capacitance, then parasitic capacitance is reduced, but wire bond flexibility and mechanical integrity are compromised
Solution Approach 1:
The bond pad structure is segmented into a small bus bar region and multiple discrete metal tiles. The bus bar provides the electrical connection with minimal area to reduce parasitic capacitance, while the metal tiles are distributed across the bond pad region to provide mechanical support and wire bond attachment points. This segmentation allows the electrical function to be separated from the mechanical function, resolving the contradiction between minimizing capacitance and maintaining wire bond flexibility.
2Object-generated harmful factors
If the bus bar area is reduced to decrease parasitic capacitance, then parasitic capacitance is reduced, but sufficient metallic surface for wire bond formation is lost
Solution Approach 1:
The bond pad is divided into a small bus bar region for electrical connection and multiple metal tiles distributed across the remaining area. The metal tiles collectively provide sufficient metallic surface area for wire bond formation while the small bus bar area minimizes parasitic capacitance.
Solution Approach 2:
Different regions of the bond pad have different functions: the bus bar region provides electrical connection with minimal area to reduce capacitance, while the metal tiles provide mechanical support and wire bond attachment. Each region is optimized for its specific function, allowing the overall structure to meet both capacitance reduction and wire bond formation requirements.
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 configuration effectively minimizes parasitic capacitance while ensuring sufficient metallic surface for wire bond formation, enhancing RF signal gain and reducing signal distortion.
Implementation Method 1
parasitic capacitance generated between the metalized bus bar bond pad and the underlying silicon layer of the device
Data Source
AI summary
A bond pad region is provided that reduces parasitic capacitance generated between bond pad metallization and underlying silicon by reducing the effective area of the bond pad, while maintaining flexibility of wire bond sites and ensuring mechanical integrity of the wire bonds. Embodiments provide, in a region that would be populated by a traditional bus bar bond pad, a small bus bar bond pad that is less than half the area of the region and populating at least a portion of the remaining area with metal tiles that are not electrically connected to the small bus bar bond pad or to each other. The metal tiles provide an attachment area for at least a portion of one or more wire bonds. Only those tiles involved in connection to a wire bond contribute to parasitic capacitance, along with the small bus bar pad.