Semiconductor Electrode Pad with Differential Bonding Heights
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Solution Overview
Problem
Semiconductor devices face damage due to high stress applied during the formation of pads and bonding wires, which can lead to increased on-state resistance and reduced breakdown voltage, making them unreliable for applications in switching power supply and inverter circuits.
Innovation Solution
A semiconductor device design featuring a semiconductor element with a semiconductor layer, electrodes, and an insulating film with raised and recessed portions on the electrode pads, allowing for differential bonding distances to reduce mechanical stress and prevent short circuits, while maintaining ohmic contact and electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pads and bonding wires are formed on the semiconductor element, then electrical connectivity is achieved, but high stress is applied to the semiconductor element causing damage
Solution Approach 1:
The patent applies beforehand cushioning by introducing a stress relief structure (such as a recess or groove) in the substrate beneath the electrode pad before bonding wire formation. This pre-configured structure absorbs and distributes the mechanical stress that will be applied during subsequent bonding wire attachment, preventing stress concentration that could damage the semiconductor element. The cushioning structure is prepared in advance to mitigate the harmful effects of mechanical stress during the bonding process.
Solution Approach 2:
The patent employs an intermediary approach by introducing a stress relief structure as a mediator between the bonding wire and the semiconductor element. This intermediate structure acts as a buffer zone that decouples the direct mechanical stress transmission path, allowing the bonding wire to be attached without directly transferring high stress to the fragile semiconductor element. The intermediary structure absorbs excess stress while maintaining electrical connectivity.
2Reliability
If bonding wires are formed to reduce on-state resistance, then electrical performance improves, but mechanical stress may cause short circuits
Solution Approach 1:
The patent applies beforehand cushioning by pre-forming a stress relief structure (recess or groove) in the substrate at the electrode pad location before bonding wire attachment. This pre-configured cushioning structure is designed to absorb and distribute the mechanical stress that will be applied during bonding wire formation, preventing stress concentration that could cause substrate cracking or electrode pad displacement leading to short circuits. The cushioning effect is established beforehand to mitigate short circuit risks during the bonding process.
3Ease of manufacture
If uniform bonding surface is used, then manufacturing is simplified, but stress distribution is uneven causing element damage
Solution Approach 1:
The patent applies local quality by creating a non-uniform bonding surface with a stress relief structure (recess or groove) at specific locations beneath the electrode pad. Instead of using a uniform bonding surface across the entire substrate, the structure introduces localized variations in thickness or geometry at critical stress concentration areas. This local modification allows the bonding surface to remain simple and easy to manufacture in most areas while providing enhanced stress distribution capabilities at the specific location where the electrode pad is attached, thus improving reliability without significantly complicating the overall manufacturing process.
Data Source
AI summary
A semiconductor device includes a first electrode on a semiconductor element at a first location and a second electrode on the semiconductor element at a second location spaced from the first location. And insulating film covers the first electrode, the second electrode and a third electrode. First and second pads are on the insulating film. The first electrode contacts the first pad through an opening in a first portion of the insulating film. The second electrode contacts the second pad each through an opening in a second portion of the insulating film. A bonding surface of the first pad is at a first distance above one portion of the insulating film, and a second distance above another. A bonding surface of the second pad likewise at different distances above the insulating film depending on location.