Semiconductor Bonding Pad Structure for Low-Load Copper Wire Joining
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Solution Overview
Problem
The bonding of copper wires in semiconductor devices requires high ultrasonic wave energy, which imposes a significant load on the semiconductor substrate, necessitating measures to reduce this load while ensuring good bonding.
Innovation Solution
A semiconductor device design featuring a first structure with a first uneven unit and a second structure with a shallower second uneven unit, where the copper wiring is joined to the second structure, reducing the load on the substrate by dispersing ultrasonic wave energy and ensuring secure bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper wire is bonded using ultrasonic wave, then good bonding is achieved, but large load acts on the semiconductor substrate
Solution Approach 1:
The bonding pad structure is segmented into multiple levels: a first bonding pad at the substrate surface, a second bonding pad covering the first pad, and a third bonding pad covering the second pad. This multi-level segmentation distributes the ultrasonic wave energy across different structural layers, reducing the load concentration on the semiconductor substrate while maintaining effective bonding contact area.
Solution Approach 2:
The bonding pad structure extends in the vertical dimension with multiple stacked layers (first, second, and third bonding pads at different heights). This dimensional extension allows the bonding interface to be distributed across multiple planes, reducing the force concentration on any single point of the substrate while maintaining total bonding area.
2Reliability
If larger ultrasonic wave energy is applied for copper wire bonding, then bonding reliability is improved, but damage risk to semiconductor substrate increases
Solution Approach 1:
The multi-level bonding pad structure acts as a cushioning mechanism before the ultrasonic wave energy reaches the substrate. The first, second, and third bonding pads with their respective uneven units distribute and absorb the impact energy, protecting the semiconductor substrate from direct high-energy exposure that could cause damage.
Solution Approach 2:
The bonding pad structures serve as intermediary elements between the copper wire and the semiconductor substrate. These pads with uneven units provide a controlled interface that mediates the energy transfer, allowing reliable bonding while preventing harmful direct contact between high-energy ultrasonic waves and the substrate.
3Ease of manufacture
If conventional single-level bonding pad is used, then manufacturing is simple, but bonding area is limited and load concentration is high
Solution Approach 1:
The bonding pad structure transitions from a conventional single-level (2D) design to a multi-level stacked configuration (3D). This dimensional change increases the total bonding surface area by utilizing vertical space, providing more contact area for wire bonding without significantly complicating the manufacturing process.
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 design achieves reduced load on the substrate during copper wire bonding, enhances bonding reliability, and improves the overall reliability of the electric power converter by securing a larger contact area and reducing manufacturing time and costs.
Implementation Method 1
there is a technique of bonding the metal wire by applying vibration energy by an ultrasonic wave to the metal wire
Data Source
AI summary
In a semiconductor device, a first structure including a first uneven unit and a second structure covering the first structure and including a second uneven unit are formed in a bonding region defined in a semiconductor substrate. Metal wiring is joined to the second uneven unit in the second structure. A depth of a recess in the second uneven unit is shallower than a depth of a recess in the first uneven unit. An insulating member defining the bonding region is formed so as to reach the semiconductor substrate.