Flip-Chip Laser Bonding for Warped Thin Semiconductor Chips
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to effectively bond semiconductor chips that are bent, warped, or prone to thermal deformation to a substrate while preventing contact failures of solder bumps during the flip-chip laser bonding process.
Innovation Solution
A flip-chip laser bonding system that includes a supply unit for substrates, a fixing unit for securing the substrate, a laser unit for bonding with a laser beam, a mask with transmission portions to focus the laser beam, and a control unit to manage the system's operations. This system applies pressure to the semiconductor chip using the mask, ensuring proper contact and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin semiconductor chip is used to achieve miniaturization, then the chip thickness is reduced, but the chip becomes bent or warped due to internal stress, causing bonding failure
Solution Approach 1:
The patent applies a pressing force to the semiconductor chip during laser bonding to change its physical state from bent to flat. The pressing unit exerts mechanical pressure on the chip surface, forcing it to conform to the substrate and ensuring proper contact between solder bumps, thereby resolving the flatness issue without changing the chip's thin dimensions
Solution Approach 2:
The patent introduces a pressing unit as an intermediary component between the laser bonding system and the semiconductor chip. This pressing unit acts as a mediator that applies controlled force to the chip during the bonding process, enabling flat contact without directly modifying the chip structure or requiring changes to the chip manufacturing process
2Reliability
If the temperature of the semiconductor chip and substrate is raised to achieve bonding, then the bonding is formed, but the chip or substrate becomes bent or warped due to thermal expansion coefficient differences, causing bonding failure
Solution Approach 1:
The patent applies a pressing force to the semiconductor chip before and during the laser heating process to counteract the thermal expansion effects. By pre-applying pressure and maintaining it during heating, the system prevents thermal warping from occurring, rather than trying to correct it after the fact. This preliminary anti-action ensures the chip remains flat throughout the thermal bonding process
Solution Approach 2:
The pressing unit is activated before the laser beam is applied to the chip-substrate assembly. This preliminary action of applying mechanical pressure ensures the chip is in a flat state before thermal expansion occurs, and the pressure is maintained throughout the heating process to prevent warping during bonding
3Strength
If the semiconductor chip is bent or warped, then the chip structure remains intact, but some solder bumps fail to contact the substrate, causing bonding failure
Solution Approach 1:
The patent applies mechanical pressure to change the physical configuration of the bent chip, forcing the solder bumps into contact with the substrate. The pressing force modifies the chip's shape locally at the bonding interface without compromising the overall structural integrity of the chip, enabling reliable solder bump contact while maintaining chip strength
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 system ensures reliable bonding of semiconductor chips to substrates, even when the chips are bent or prone to thermal deformation, by applying pressure through the mask and using a focused laser beam to prevent solder bump contact failures.
Implementation Method 1
the semiconductor chip is irradiated with a laser beam to transmit energy, so that the solder bump melts and hardens instantaneously
Implementation Method 2
the solder bump melts and hardens instantaneously
Implementation Method 3
a mask having a plurality of transmission portions that transmit a laser beam irradiated from the laser head of the laser unit
Data Source
AI summary
Provided is a flip-chip laser bonding system for bonding a semiconductor chip in the form of a flip chip to a substrate using a laser beam. In the flip-chip laser bonding system, the semiconductor chip is laser-bonded to the substrate while pressure is applied to the semiconductor chip. Accordingly, even a semiconductor chip that is bent or is capable of being bent can be bonded to a semiconductor chip without contact failure.