Semiconductor Die Edge Ledge Structure for High Voltage Protection
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Solution Overview
Problem
High voltage semiconductor devices experience failures due to electrical shorting at the edge of the semiconductor die, primarily caused by the coupling of high voltage signals leading to electrical shorting from the semiconductor material to conductors, which existing packaging methods fail to adequately address.
Innovation Solution
The formation of a ledge at the edge of the semiconductor die, covered with a protective passivation layer, increases the distance between bond wires or conductors and the semiconductor substrate, thereby reducing or preventing failures by using a passivation layer with higher breakdown voltage than the mold compound, ensuring the semiconductor device can handle higher voltages without electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing packaging methods are used for high voltage semiconductor devices, then the device structure is simple and manufacturing is easy, but electrical shorting occurs at the die edge causing device failure
Solution Approach 1:
The patent introduces a multi-dimensional approach by creating a ledge structure that extends from the die edge into the mold compound, and forming a passivation layer that covers the ledge and extends onto the mold compound surface. This three-dimensional structure adds spatial separation between conductors and the semiconductor die, increasing the electrical breakdown path length and preventing edge-related shorting in high voltage devices
Solution Approach 2:
The passivation layer acts as an intermediary material between the semiconductor die and the surrounding mold compound/conductors. This intermediate layer provides enhanced electrical insulation and creates an additional breakdown barrier, preventing direct electrical discharge paths that would otherwise occur at the die edge in high voltage conditions
2Reliability
If the distance between bond wires and semiconductor substrate is increased to prevent electrical shorting, then electrical shorting is reduced, but the device size increases
Solution Approach 1:
The patent applies local quality enhancement by concentrating the electrical insulation improvements specifically at the die edge region where shorting is most likely to occur. The ledge and passivation layer are formed locally at the perimeter rather than uniformly across the entire device, providing enhanced protection where needed while maintaining compact overall dimensions
Solution Approach 2:
Instead of increasing horizontal separation distance between conductors and die, the patent utilizes the vertical dimension by forming a ledge that extends downward into the mold compound and creating a multi-layer passivation structure. This vertical separation achieves electrical isolation without increasing the device's planar footprint
3Reliability
If a passivation layer with higher breakdown voltage is used to protect the die edge, then electrical shorting is prevented, but manufacturing complexity increases
Solution Approach 1:
The passivation layer is formed as part of the semiconductor fabrication process before the die is packaged, allowing the protective structure to be created while the die is still in wafer form. This preliminary action integrates the protection layer into the manufacturing flow without requiring separate post-packaging processing steps
Solution Approach 2:
The patent merges the formation of the ledge structure and the passivation layer into a single integrated process sequence. The ledge is formed by etching or mechanical means, and the passivation material is then deposited to cover both the ledge and the surrounding area, combining structural modification and insulation application in one manufacturing flow
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
The solution effectively reduces the occurrence of electrical shorts and enhances the ability of packaged semiconductor devices to withstand higher voltage signals by increasing the distance between conductors and the semiconductor edge, thereby improving the reliability and performance of high voltage semiconductor devices.
Implementation Method 1
using a passivation layer with higher breakdown voltage than the mold compound, ensuring the semiconductor device can handle higher voltages without electrical shorts
Data Source
AI summary
In a described example a device includes: a first corner formed between a circuit side surface of a semiconductor die and a first sidewall formed with a first depth extending along a side of the semiconductor die from the circuit side surface; a ledge having a planar surface formed parallel to the circuit side surface of the semiconductor die formed at the first depth from the circuit side surface at the first corner, and being perpendicular to the first sidewall; a second corner formed by an intersection of the planar surface of the ledge and a scribe lane sidewall of the semiconductor die, forming a second sidewall perpendicular to the circuit side surface; and portions of the circuit side surface of the semiconductor die, the first corner, the first sidewall, and the planar surface of the ledge covered by a passivation layer.