Die-to-die wire-bonding with variable bump sizes
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Solution Overview
Problem
The challenge in die-to-die wire-bonding lies in achieving reliable and high-quality bonds with smaller die pad openings and pitches, where the use of smaller diameter wires results in undesirable bond quality due to the small bump size, especially when die pads are probed or scuffed.
Innovation Solution
The method involves bonding a first conductive bump of a larger size to a first die pad and a second conductive bump of a smaller size to a second die pad, with the first wire bonded to both bumps using different bond tools, allowing for varying wire diameters and materials like gold, aluminum, or copper, to enhance bond reliability and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If smaller diameter wires are used to accommodate smaller die pad openings and pitches, then the wire can fit the smaller pads, but the bond quality and reliability deteriorate due to small bump size
Solution Approach 1:
The patent applies different bump sizes at different locations: a first bump size for the first die pad and a second bump size for the second die pad. This local differentiation allows each bump to be optimized for its specific bonding requirements, resolving the contradiction between fitting small pads and ensuring bond reliability.
Solution Approach 2:
The patent changes the bump size parameter between different bonding locations. By using a first bump size for the first die pad and a second bump size for the second die pad, the system optimizes bonding reliability for each location independently, particularly when die pads have been probed or scuffed.
2Length of moving object
If smaller diameter wires are used for wire-bonding, then they can accommodate smaller die pad pitches, but the bump size becomes too small leading to undesirable bond quality
Solution Approach 1:
The patent implements local quality by forming a first bump of a first size and a second bump of a second size at different locations. This allows the bonding process to have different quality characteristics at different locations, with larger bumps providing more robust bonding where needed.
Solution Approach 2:
The bonding process is segmented into two distinct bonding operations: bonding a first wire to a first die pad with a first bump, and bonding a second wire to a second die pad with a second bump. This segmentation allows independent optimization of each bonding operation.
3Device complexity
If the same bond tool is used for both die pads, then the process is simpler, but bond reliability deteriorates when die pads have different conditions (probed or scuffed)
Solution Approach 1:
The patent applies local quality by using a first bond tool for bonding to the first die pad and a second bond tool for bonding to the second die pad. Each bond tool can be optimized for its specific bonding conditions, improving reliability when die pads have different conditions such as being probed or scuffed.
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 results in high reliability and quality bonding, particularly beneficial for fine-pitched dies, reducing the likelihood of shorting and improving bond strength by using differing bump sizes and bond tools, thus addressing the limitations of smaller wire diameters.
Implementation Method 1
wires having smaller diameters have had to be used for wire-bonding so that the bumps formed therefrom (by electrostatic charge, for example) can be bonded to the die pads
Data Source
AI summary
Methods for die-to-die wire-bonding, and devices and systems formed thereby, are described herein. A die to die wire-bonding method may comprise bonding a first conductive bump having a first bump size to a first die pad; bonding a first wire to a second die pad, the first wire bonded to the second die pad by a second conductive bump having a second bump size, the second bump size being smaller than the first bump size; and bonding the first wire to the first conductive bump.