Semiconductor Vertical Wire Bonding Dummy Pad Structure
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Solution Overview
Problem
In vertical wire bonding, the lack of an exclusive pad at the second solder joint leads to wire cutting damage, resulting in surface pits and uneven surfaces, which can cause peeling and affect electrical signal transmission and chip performance.
Innovation Solution
A dummy pad is introduced at the second solder joint, allowing the metal wire to be cut and broken above the wire bonding pad, using a chopper with a controlled thickness and surface area to minimize damage and ensure flatness, thereby improving the vertical wire bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wire cutting is performed at the second solder joint without an exclusive pad, then the vertical wire bonding process can be completed, but the wire cutting action damages the front layer creating pits and uneven surfaces
Solution Approach 1:
The patent divides the second solder joint area into two functional parts: a dummy pad for wire cutting and a front layer area for signal transmission. This segmentation allows the wire cutting operation to be isolated to the dummy pad, preventing damage to the front layer and maintaining its flatness while still enabling complete vertical wire bonding process
Solution Approach 2:
The dummy pad acts as an intermediary structure that absorbs the mechanical damage from wire cutting. By providing a dedicated cutting platform, the dummy pad protects the front layer from pits and uneven surfaces, allowing the wire cutting function to be performed without compromising the integrity of the signal transmission layer
2Productivity
If wire cutting is performed at the front layer, then the vertical wire bonding process can be completed, but peeling may occur due to surface unevenness
Solution Approach 1:
The patent segments the second solder joint into a dummy pad specifically for wire cutting and separates it from the front layer. This spatial segmentation ensures that the mechanical stress and damage from wire cutting are confined to the dummy pad, preventing peeling in the front layer and improving overall structural reliability
Solution Approach 2:
The dummy pad serves as a mediator that absorbs the mechanical impact of wire cutting. By providing a dedicated sacrificial structure, the dummy pad prevents the propagation of stress and damage to the front layer, thereby eliminating the root cause of peeling and improving the reliability of the bonded structure
3Productivity
If wire cutting damage creates pits in the PI/metal layer, then the vertical wire bonding process can be completed, but electrical signal transmission may be interrupted
Solution Approach 1:
The patent segments the second solder joint area into a dummy pad for wire cutting and a front layer for electrical signal transmission. This segmentation ensures that wire cutting operations are isolated to the dummy pad, preventing the creation of pits in the PI/metal layer that would otherwise interrupt electrical signal transmission
Solution Approach 2:
The dummy pad acts as an intermediary that absorbs the wire cutting operation, preventing damage to the front layer's PI/metal structure. By confining the cutting action to the dummy pad, the integrity of the electrical signal transmission path in the front layer is preserved, eliminating signal interruption risks
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 dummy pad enhances the flatness of the semiconductor chip surface, reduces the risk of peeling, and improves the transmission performance and efficiency of the vertical wire bonding process by dispersing pressure and preventing excessive depression at the solder joints.
Implementation Method 1
melting a wire tail of the metal wire into a metal ball
Implementation Method 2
press-welding the metal ball onto a surface of the wire bonding pad
Implementation Method 3
thinning the metal wire on a surface of the dummy pad
Data Source
AI summary
The present disclosure provides a semiconductor IC structure having vertical wire bonding and method of making it. The method includes two steps. First step: providing a semiconductor chip, disposing a first solder joint and a second solder joint separately on its surface, disposing a wire bonding pad at the first solder joint, to connect to an internal functioning device of the semiconductor chip, and disposing a dummy pad at the second solder joint. Second step: bonding a metal wire on the wire bonding pad, cutting the metal wire on the dummy pad, and breaking the metal wire by pulling above the wire bonding pad, to obtain a vertical conductive column connected to the wire bonding pad.