Semiconductor Source Pad with Segmented Plating for Inspection and Bonding
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Solution Overview
Problem
Conventional semiconductor devices face challenges in passing large currents during screening due to poor adhesion between Al electrode pads and plating films, leading to potential cracks and inadequate bonding strength, limiting the optimal use of single source pads for multiple purposes.
Innovation Solution
A semiconductor device structure featuring a source pad with distinct first and second portions, where the first portion is covered with a hard metal film for improved durability and contact resistance during inspection, and the second portion is used for bonding wires, allowing for enhanced bonding strength and current passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a plating film is provided on the Al electrode pad surface to improve bonding strength, then bonding strength improves, but contact resistance increases and large current passage becomes difficult
Solution Approach 1:
The electrode pad is divided into two regions with different structures: a first region without plating film for low contact resistance and large current passage, and a second region with plating film for high bonding strength. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The electrode pad surface is segmented into multiple regions with different characteristics. The first region (without plating) handles electrical contact requirements, while the second region (with plating) handles bonding requirements, allowing both contradictory requirements to be satisfied simultaneously in different locations.
2Reliability
If the Al electrode pad surface is left exposed without plating film to reduce contact resistance, then contact resistance decreases, but bonding strength deteriorates
Solution Approach 1:
Different regions of the electrode pad have different surface qualities: the first region has exposed Al for low contact resistance, while the second region has plating film for high bonding strength. This resolves the contradiction by assigning different properties to different locations based on functional requirements.
3Device complexity
If a single source pad is used for both inspection and bonding purposes, then device complexity reduces, but the pad cannot withstand large inspection currents due to poor adhesion
Solution Approach 1:
The electrode pad structure is designed to perform multiple functions: the first region enables electrical inspection with large currents, while the second region enables wire bonding. This multi-functional design allows a single pad structure to replace what would traditionally require separate pads, reducing device complexity while maintaining reliability.
Solution Approach 2:
The multi-functional pad achieves both inspection and bonding capabilities through local differentiation: the plating-free first region optimizes for electrical contact during inspection, while the plating-covered second region optimizes for mechanical bonding, allowing the single pad to handle both functions reliably.
Data Source
AI summary
A portion of a source electrode exposed by an opening in a passivation film is used as a portion of a source pad. A first portion of the source pad includes a plating film formed by a material that is harder than a material of the source electrode. During screening, a probe needle that is a metal contact contacts the plating film that is on the first portion of the source pad. A second portion of the source pad has a layer structure different from that of the first portion of the source pad and in a second direction parallel to the front surface of the semiconductor chip, is disposed adjacently to and electrically connected to the first portion of the source pad. A bonding wire is wire bonded to the second portion of the source pad after an inspection process of the semiconductor chip.