Active Power Device Terminal Structure for Standing Wave Dissipation
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Solution Overview
Problem
High power semiconductor devices, such as LDMOS devices, experience mutual electromagnetic coupling between bonding wire arrays and the ground plane, leading to non-uniform RF voltage and current distributions, which cause parasitic lateral standing waves that degrade linearization and can be destructive to device components.
Innovation Solution
A terminal structure with a conductive sub-structure is introduced, positioned between the fundamental signal layer and the reference voltage plane, allowing lateral currents to flow through the sub-structure instead of the signal layer, and incorporating resistive properties to dissipate standing waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If bonding wire arrays are used for high power semiconductor devices, then electrical connection and signal transmission are achieved, but mutual electromagnetic coupling occurs between the bonding wire arrays and the ground plane causing non-uniform RF voltage and current distributions
Solution Approach 1:
A conductive sub-structure is introduced as an intermediary element between the fundamental signal layer and the reference voltage plane. This sub-structure provides a dedicated path for lateral currents to flow, preventing them from traveling through the bonding wire arrays and ground plane where they would cause harmful electromagnetic coupling and non-uniform voltage distribution.
Solution Approach 2:
The current path is segmented into separate channels: the fundamental signal flows through the fundamental signal layer while lateral currents are directed through the conductive sub-structure. This segmentation prevents the mixing of signal current and return current, eliminating the harmful electromagnetic coupling effects.
2Reliability
If lateral currents flow through the fundamental signal layer, then electrical continuity is maintained, but parasitic lateral standing waves occur that degrade linearization and can be destructive to device components
Solution Approach 1:
The conductive sub-structure serves as an intermediary current path that captures lateral currents before they can flow through the fundamental signal layer. By providing this alternative path, the harmful standing waves are prevented from forming in the signal-critical regions while electrical continuity is preserved through the sub-structure.
Solution Approach 2:
Lateral currents are extracted from the fundamental signal layer and redirected through the conductive sub-structure. This extraction removes the harmful standing wave phenomenon from the signal path while maintaining the necessary electrical continuity through the sub-structure's connection to the reference voltage plane.
3Reliability
If a conductive sub-structure is introduced to separate lateral currents, then parasitic standing waves are reduced, but device structure complexity increases
Solution Approach 1:
The conductive sub-structure is implemented as a thin conductive layer or film positioned between the fundamental signal layer and the reference voltage plane. This thin-film approach provides the necessary current separation function while minimizing the added structural complexity and maintaining compatibility with standard semiconductor manufacturing processes.
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 solution effectively separates lateral currents from the fundamental signal, reducing parasitic standing waves and improving the uniformity of impedance and signal quality in high-frequency semiconductor devices.
Implementation Method 1
at least a portion of the lateral currents generated by non-uniformity of lateral RF voltages along the terminal structure will flow through the conductive sub-structure
Implementation Method 2
by providing resistive properties within the lateral current flow path of the conductive sub-structure, lateral standing waves and currents occurring within the terminal structure can be dissipated within the conductive sub-structure
Data Source
AI summary
A semiconductor die comprising a terminal structure for an active power device. The terminal structure comprises a metallic layer arranged to be electrically coupled between the active power device and an external contact of an integrated circuit package, a conductive sub-structure extending in parallel with the metallic layer, and located such that, when mounted within an integrated circuit device, the conductive sub-structure lies between the metallic layer and a reference voltage plane, and interconnecting elements extending between the metallic layer and the conductive sub-structure and electrically coupling the metallic layer to the conductive sub-structure. The plurality of interconnecting elements comprise first and second interconnecting elements extending between first and second lateral end regions of the metallic layer and the conductive sub-structure respectively such that the first and second interconnecting elements are laterally spaced with respect to the direction of travel of the fundamental signal for the active power device.