Bond Pad Structure With Nested Metal Layer
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Solution Overview
Problem
Conventional bond pad structures face issues such as mechanical scratching, inadequate heating during sputtering procedures, and increased risk of leakage currents due to the exposed second metal layer, which affects the manufacturability and reliability of semiconductor devices.
Innovation Solution
A bond pad structure is designed with a second metal layer positioned below the second isolator layer, ensuring it is protected from scratches and with a thickness less than the first isolator layer, and a method involving a substrate with a first and second isolator layer, where the second metal layer is deposited on top of the first metal layer and overlaps the second isolator layer, maintaining good solderability and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second metal layer is exposed on the bond pad structure, then good solderability is achieved, but the second metal layer is vulnerable to mechanical scratching
Solution Approach 1:
The patent applies the nesting principle by placing the second metal layer (solderable layer) underneath the second isolator layer (silicon nitride layer). This nested configuration allows the second metal layer to remain protected by the overlying isolator layer during handling and processing, while still providing solderability through the sidewalls and bottom surfaces that are exposed to the bonding partner.
2Temperature
If the second metal layer is positioned at the highest point of the bond pad structure, then solderability is improved, but thermal contact with the chuck during sputtering causes insufficient heating of the substrate
Solution Approach 1:
The patent resolves the thermal contact issue by changing the vertical positioning of the second metal layer from the highest point to a lower position beneath the second isolator layer. This dimensional repositioning eliminates direct thermal contact with the sputtering chuck, allowing the substrate to be properly heated during sputtering procedures while the second metal layer remains accessible for soldering through sidewall and bottom exposure.
3Reliability
If the second metal layer overlaps the silicon nitride layer in a region above the oxide layer, then solderability is enhanced, but the path length for leakage currents is reduced
Solution Approach 1:
The patent applies nesting by positioning the second metal layer underneath the second isolator layer, which creates a longer lateral path for leakage currents to travel from the contacted second region to the silicon substrate. The second isolator layer acts as an additional barrier that the leakage currents must traverse, thereby increasing the leakage path length and improving reliability.
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 configuration enhances the reliability and manufacturability of semiconductor devices by protecting the second metal layer from scratches and ensuring sufficient heating during sputtering, while reducing the risk of leakage currents, thereby improving the overall performance and lifespan of the chip.
Implementation Method 1
problems can occur during sputtering procedures for metallization of the backside of the silicon substrate 103
Data Source
Figure 1~2
Figure 3(a)~3(c)
AI summary
It is described a bond pad structure and a method for producing the same, the bond pad structure (1), comprising: a substrate (3) having a surface (17)to be electrically contacted; a first isolator layer (5) contacting the surface (17) of the substrate in a first region (a); a first metal layer (9) contacting the surface (17) of the substrate (3) in a second region (b) adjacent the first region (a) and partly overlapping the first isolator layer (5); a second isolator layer (11) at least partly overlapping the first isolator layer (5) and the first metal layer (9); a second metal layer (13) at least partly overlapping the second isolator layer (11) in the second region (b); wherein a maximum thickness (U) of the second metal layer (13) perpendicular to the surface (17) of the substrate (3) is smaller than a maximum thickness (t0) of the first isolator layer (5) perpendicular to the surface (17) of the substrate (3). The surface of the second isolator layer forming the highest level provides scratching protection for the bond pad structure.