Semiconductor Flip-Chip Bonding Thermal Expansion Control
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Solution Overview
Problem
Conventional flip chip bonding techniques fail to maintain the quality of bumps during the bonding process due to thermal expansion of the mounting tool, leading to increased load on the chip and potential crushing or spreading of bumps, which can result in short circuits and improper gap maintenance between the chip and substrate.
Innovation Solution
A manufacturing apparatus and method that includes a stage, mounting tool, pressing mechanism, and controller to monitor and adjust the positional deviation of the mounting tool vertically, maintaining a constant load by updating the command position based on thermal expansion, and detecting bump melting through changes in pressing load, ensuring the gap between the chip and substrate is maintained at a target value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the position of the mounting tool is held constant during heating, then the control simplicity is maintained, but the load applied to the chip gradually increases due to thermal expansion, causing the bumps to be crushed
Solution Approach 1:
The mounting tool's command position is dynamically adjusted during heating based on detected thermal expansion amounts. Instead of holding the position constant, the system continuously updates the command position to compensate for thermal expansion, thereby maintaining constant load on the chip while accounting for the dynamic changes in tool dimensions.
Solution Approach 2:
The system uses feedback from thermal expansion detection to adjust the mounting tool's position. By detecting the thermal expansion amount and using this information to update the command position, the system creates a closed-loop control that prevents bump crushing while maintaining manufacturing precision.
2Device complexity
If the mounting tool position is not adjusted for thermal expansion, then the positional control is simple, but the gap between chip and substrate cannot be maintained at appropriate value
Solution Approach 1:
The system dynamically adjusts the mounting tool's command position during the heating process based on detected thermal expansion. This dynamic adjustment ensures that the gap between the chip and substrate is maintained at the appropriate value throughout the bonding process, rather than relying on static position control.
Solution Approach 2:
The system performs preliminary detection of thermal expansion and uses this information to proactively adjust the command position before excessive gap variation occurs. This preliminary action allows the system to maintain precise gap control by anticipating and compensating for thermal expansion effects.
3Device complexity
If continuous heating is performed without detecting melting timing, then the process control is simple, but the bumps may be crushed and spread causing short circuits
Solution Approach 1:
The system uses feedback from load detection to identify the melting timing of bumps. By monitoring changes in pressing load during heating and detecting the characteristic decrease that occurs at melting, the system can automatically determine when to stop heating, preventing over-heating and bump degradation while maintaining reliable electrical connections.
Solution Approach 2:
The system replaces simple time-based or temperature-based control with a mechanical load detection mechanism. By using load detection to identify melting timing, the system achieves more precise control over the bonding process, ensuring bumps are heated sufficiently to melt and bond without being overheated to the point of crushing and spreading.
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 effectively prevents excessive crushing of bumps and maintains the quality of the bonding process by accurately detecting melting timing and adjusting for thermal expansion, ensuring proper gap maintenance and preventing short circuits.
Implementation Method 1
the chip is heated by the mounting tool
Implementation Method 2
until the bump melts
Implementation Method 3
the mounting tool extends axially due to thermal expansion
Data Source
AI summary
A manufacturing apparatus of a semiconductor device includes a stage, a mounting tool, a pressing mechanism, and a controller. The pressing mechanism moves the mounting tool in a vertical direction and applies a load to a chip. The controller is configured to perform a first process and a detection process. In the first process, after bringing the chip into contact and until a bump melts, the chip is heated by the mounting tool and a command position of the pressing mechanism is constantly updated so that a positional deviation is constant. In the detection process, melting of the bump is detected based on a decrease in the pressing load.