Semiconductor Device Busbar Cross-Section Optimization
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Solution Overview
Problem
As semiconductor devices are miniaturized, increased current densities lead to susceptibility to damage from Ohmic overheating and electromigration, and uneven current distribution reduces their overall current passing capacity.
Innovation Solution
The use of comb electrodes with busbars that decrease in cross-section and interleaving conductive fingers to stabilize current density along the length of the electrodes, ensuring a consistent current flow by adjusting the cross-sectional area in proportion to the current magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If SDs are reduced in size to achieve higher device concentration, then device density increases, but current density increases leading to Ohmic overheating and electromigration
Solution Approach 1:
The busbar cross-sectional area is varied along its length to create non-uniform current density distribution. The cross-section is larger at regions where current magnitude is higher and smaller where current is lower, optimizing heat dissipation and reducing electromigration risk at each location
Solution Approach 2:
The geometric parameter of the busbar (cross-sectional area) is changed along its length to compensate for current density variations. This parameter modification allows the electrode to maintain stable current density despite miniaturization effects
2Ease of manufacture
If electrodes are formed as patterned thin metal layers of uniform thickness, then manufacturing is simplified, but current density becomes uneven along the electrode length
Solution Approach 1:
Instead of uniform thickness throughout, the busbar cross-sectional area is locally adjusted along its length. Regions with higher current carry larger cross-sections while regions with lower current have smaller cross-sections, creating optimal current density distribution
Solution Approach 2:
The electrode geometry transitions from a static uniform structure to a dynamic structure where cross-sectional area varies continuously or in steps along the length, adapting to the varying current requirements at different positions
3Reliability
If current density is unevenly distributed through the SD, then current passing capacity is reduced, but increasing electrode cross-section increases device area
Solution Approach 1:
The cross-sectional area parameter of the busbar is optimized along its length to match the current distribution, maximizing current passing capacity without requiring uniform increase in overall electrode dimensions
Solution Approach 2:
Current density is equalized at each location by locally adjusting the cross-sectional area, ensuring optimal current utilization throughout the electrode structure without unnecessary area expansion
Data Source
AI summary
An embodiment of the invention relates to a semiconductor device comprising: first and second electrodes comprising first and second busbars respectively that decrease in cross section in opposite directions; and a plurality of interleaving first and second conducting fingers that extend from the first and second busbars respectively.