Galvanically Isolated Signal Transfer Coupler with Mushroom-Shaped Diffusion Barrier
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Solution Overview
Problem
Existing semiconductor devices face challenges in providing reinforced galvanic isolation for high-voltage applications, particularly in preventing current flow between electric circuits with different ground potentials while enabling bidirectional signal exchange, especially when subjected to surge pulses exceeding 10kV.
Innovation Solution
A semiconductor device with a galvanically isolated signal transfer coupler incorporating a contact pad with a metallic base layer, diffusion barrier layer, wire bondable layer, and passivation layer, along with inductive or capacitive couplers, provides reinforced galvanic isolation through a mushroom-shaped diffusion barrier layer and multiple isolation layers, ensuring robustness against transient voltage spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thin isolation layer is used to allow bidirectional signal transmission, then signal transmission efficiency is improved, but galvanic isolation strength deteriorates
Solution Approach 1:
The isolation structure is segmented into multiple layers (first isolation layer, second isolation layer, third isolation layer, fourth isolation layer) with different materials and functions. Each layer contributes to the overall isolation strength, allowing the system to achieve both thin effective isolation distance for signal transmission and cumulative isolation strength for high-voltage protection.
Solution Approach 2:
The patent uses composite material structures including SiOx, phosphosilicate glass, hydrogenated SixNy, and imide layers combined in a multi-layer configuration. This composite approach allows optimization of both signal transmission properties (through controlled thickness and material selection) and isolation strength (through material diversity and layer stacking).
2Ease of manufacture
If the contact pad structure is simplified, then manufacturing complexity is reduced, but reliability under high-voltage stress deteriorates
Solution Approach 1:
The contact pad structure implements local quality by creating a mushroom-shaped diffusion barrier layer with specific geometric characteristics (protruding second portion, curved periphery) only at critical locations where high-voltage stress concentrates. The metallic base layer, diffusion barrier layer, wire bondable layer, and passivation layer are configured with locally optimized properties to enhance reliability precisely where needed without complicating the entire device structure.
Solution Approach 2:
The diffusion barrier layer features a curved surface at its periphery and a mushroom-shaped profile with a protruding second portion. This curvature eliminates sharp edges that would concentrate electric field stress during transient voltage spikes, distributing the stress more evenly and improving reliability without adding manufacturing complexity.
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 increases the operational lifetime of semiconductor devices by providing reliable bidirectional signal exchange with enhanced galvanic isolation, capable of withstanding surge pulse isolation voltages of at least 10kV peak, thus meeting industry standards for high-voltage applications.
Implementation Method 1
An example of a device for inductive galvanic isolation and signal exchange is a coreless transformer which includes a primary winding and a secondary winding separated by an isolation layer that is sufficiently thin to allow bidirectional transmission of signals.
Implementation Method 2
a metallic diffusion barrier layer arranged on the metallic base layer
Data Source
Figure 1A~1C
Figure 2
Figure 3A
AI summary
In an embodiment, a semiconductor device includes a galvanically isolated signal transfer coupler comprising a contact pad. The contact pad includes a metallic base layer (93), a first isolation layer arranged on peripheral regions of the metallic base layer (93) and having a first opening exposing a portion of the metallic base layer (93), a metallic diffusion barrier layer (97) arranged on the metallic base layer (93). The metallic diffusion barrier layer (97) includes a first portion and a second portion, wherein the second portion of the metallic diffusion barrier layer (97) is arranged in the first opening in the first isolation layer (102) and the first portion of the metallic diffusion barrier layer (97) extends onto a surface of the first isolation layer (102) adjacent the first opening. The first portion has a first surface and a second surface opposing the first surface. The first surface includes a curved surface at the periphery. The first portion extends in a transverse plane and has a width. The second portion protrudes from the second surface intermediate the width of the first portion.