Flip Chip Bonding Tool Protrusion Pattern for Uniform Chip Temperature
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Solution Overview
Problem
In flip chip bonding processes, existing technologies face challenges in maintaining uniform temperature distribution across semiconductor chips during laser bonding, leading to potential defects due to thermal stress and warpage, especially when using conventional convection reflow methods or bonding tools with direct contact that hinder heat transfer uniformity.
Innovation Solution
A bonding tool with a configuration that minimizes contact area through the use of contact protrusions on its surface, allowing for controlled heat transfer, formed in a pattern that reduces heat transfer from the center to the outer parts of the semiconductor chip, ensuring uniform temperature distribution using vacuum adsorption and a non-contact thermometer for temperature monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat is applied to the substrate during convection reflow bonding, then bonding between semiconductor chip and substrate is achieved, but the substrate expands causing damage to bumps or fine circuit layer due to thermal expansion difference
Solution Approach 1:
The patent extracts the heating function from the substrate and applies it only to the semiconductor chip using a laser beam. The bonding tool serves only as a pressing mechanism while the laser generator provides localized heating to the chip, completely separating the heating source from the substrate to avoid its thermal expansion
Solution Approach 2:
The patent introduces a laser beam as an intermediary heating medium that transfers energy selectively to the semiconductor chip without heating the substrate. The laser acts as a mediator that enables bonding while avoiding the harmful thermal expansion of the substrate that would occur with conventional convection heating
2Force
If a bonding tool with large contact area is used to press the semiconductor chip, then bonding pressure is improved, but heat transfer from the chip to the tool increases causing non-uniform temperature distribution
Solution Approach 1:
The bonding tool features a contact surface with non-uniform structure consisting of protrusions and recesses, where the protrusion areas provide pressing force while the recess areas reduce heat transfer. This local variation in contact quality allows simultaneous achievement of adequate bonding pressure and uniform temperature distribution by controlling where heat can and cannot transfer
Solution Approach 2:
The contact surface of the bonding tool is segmented into multiple protrusion regions and recess regions rather than being a continuous flat surface. This segmentation separates the functions of pressure application (protrusions) and heat transfer control (recesses), enabling independent optimization of both bonding pressure and temperature uniformity
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 configuration enables efficient and uniform heat distribution across the semiconductor chip, reducing thermal stress and improving bonding quality by maintaining a consistent temperature from the center to the outer parts, even with lower laser output, thus enhancing the reliability of the bonding process.
Implementation Method 1
The temperature of the semiconductor chip is rapidly increased simultaneously with absorbing energy oscillating from the laser beam
Implementation Method 2
heat from the semiconductor chip, which is primarily heated by absorbing the energy from the laser beam transmitted by the bonding tool, is returned to the bonding tool
Implementation Method 3
a bonding tool which presses a semiconductor chip while transmitting a laser beam
Data Source
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AI summary
Disclosed is a bonding tool (10) for simultaneously heating a semiconductor chip using a laser and bonding the semiconductor chip in a flip chip laser bonding process, in which a vacuum wall (W) configured to maintain a vacuum at a time of adsorbing the semiconductor chip is formed at the outer parts of the bottom surface of the bonding tool (10), and a plurality of contact protrusions (E1-E6) is formed lengthwise and breadthwise (or widthwise) on the bottom surface of the bonding tool (10) in a pattern configured such that a heat transfer area of the semiconductor chip to the bonding tool (10) at the center of the semiconductor chip is relatively large and the heat transfer area is gradually reduced in the direction towards the outer parts of the semiconductor chip so as to achieve a uniform temperature distribution from the center to the outer parts of the semiconductor chip.