Conductive Pad Etch Stop Layer for Parasitic Effect Control
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Solution Overview
Problem
Semiconductor packaging introduces parasitic effects due to variations in conductive pads, which can significantly alter the performance of semiconductor chips, necessitating the minimization of these effects.
Innovation Solution
The implementation of a device with a first conductive pad, an etch stop layer, a solder barrier layer, and a solder metal layer, where the solder layer is selectively removed from the first conductive pad using a specific etch process, and the etch stop layer is selectively removed relative to the underlying first conductive pad, allowing for precise control of pad thickness and minimizing parasitic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging structures are used, then manufacturing is simpler, but parasitic effects increase and performance deteriorates
Solution Approach 1:
The conductive pad is segmented into multiple functional layers: a base conductive pad layer, an etch stop layer, and a solder barrier layer. Each layer serves a specific function - the etch stop layer prevents over-etching to maintain consistent pad thickness, while the solder barrier layer reduces parasitic effects. This segmentation allows precise control of pad properties without complicating the overall manufacturing process.
Solution Approach 2:
Different regions of the pad structure have different properties tailored to specific functions. The etch stop layer has selective etch resistance to protect the conductive pad during processing, while the solder barrier layer has specific electrical properties to minimize parasitic effects. This local differentiation of material properties optimizes performance while maintaining manufacturing simplicity.
2Manufacturing precision
If pad thickness varies, then manufacturing is easier, but parasitic effects increase
Solution Approach 1:
The etch stop layer is applied in advance before the final etching process. This preliminary protective layer ensures that the conductive pad thickness remains consistent by preventing over-etching, while the etch stop layer itself can be easily removed afterward using selective etching. This approach maintains manufacturing simplicity while achieving precise pad thickness control.
3Adaptability or versatility
If solder layer is present on all pads, then soldering is simplified, but wire bonding pads are contaminated
Solution Approach 1:
The solder barrier layer is selectively applied only to pads that require soldering, while wire bonding pads remain without this layer. This local differentiation allows each pad type to have the appropriate properties - solderable pads have the barrier layer for reliable solder joints, while wire bonding pads maintain their original surface for optimal wire adhesion. This approach maintains versatility without requiring complex selective processing.
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 approach effectively minimizes parasitic effects by ensuring consistent pad thickness and reducing electrical interference, thereby enhancing the performance and reliability of semiconductor chips.
Implementation Method 1
The solder layer is removed from over the first conductive pad using a first etch process
Implementation Method 2
The etch stop layer is removed from over the first conductive pad using a second etch process. The second etch process selectively removes the etch stop layer relative to the underlying first conductive pad
Data Source
AI summary
In one embodiment, a device includes a first conductive pad disposed over a substrate, and a etch stop layer disposed over a top surface of the first conductive pad. The device further includes a solder barrier disposed over the etch stop layer.