PI Tape Support for Semiconductor Die Warpage During LAB
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Solution Overview
Problem
Semiconductor devices experience warpage during laser-assisted bonding (LAB) due to heat-induced stress, particularly for large and/or thin wafers, which complicates process control and increases the risk of bump-pad misalignment, and temperature monitoring is impractical with infrared cameras.
Innovation Solution
The use of polyimide (PI) tape as a structural support layer on the back surface of semiconductor devices during LAB, providing heat resistance and high transmittance to minimize stress and warpage, allowing for effective temperature monitoring and improved process control by absorbing little to no laser power and maintaining manufacturing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If compression LAB (cLAB) is used to handle devices with high susceptibility to warpage, then warpage control is improved, but process complexity increases due to multiple control parameters and alignment risks
Solution Approach 1:
A susceptor layer is introduced as an intermediary between the semiconductor device and the bonding process. This susceptor absorbs laser energy and converts it to heat, which is then conducted to the bonding interface. This mediator enables temperature monitoring and control without directly exposing the device to laser heating, thereby reducing warpage while simplifying process control.
Solution Approach 2:
The patent replaces the mechanical compression system of cLAB with a thermal field-based approach using laser heating of the susceptor. Instead of applying compressive force and monitoring multiple mechanical parameters, the system uses optical heating with temperature monitoring, reducing process complexity while maintaining warpage control.
2Ease of manufacture
If laser emission is projected to the bonding surface to melt fusible material, then bonding is achieved, but heat-induced stress and warpage increase due to large area heating
Solution Approach 1:
The susceptor acts as a thermal mediator that distributes laser energy over a larger area before it reaches the device, reducing localized heat-induced stress and warpage while still enabling effective bonding through controlled heat conduction to the bonding interface.
Solution Approach 2:
The patent changes the heating parameter distribution by using the susceptor to convert concentrated laser energy into distributed thermal energy. This allows the bonding process to proceed with reduced peak temperatures and more uniform heat distribution, minimizing warpage and stress.
3Stability of the object's composition
If compression pressure is applied during laser emission, then warpage is reduced, but bump-pad misalignment risk increases
Solution Approach 1:
The patent replaces mechanical compression with optical-thermal processing using laser heating of the susceptor. This substitution eliminates the need for mechanical force application, thereby avoiding alignment issues associated with compression while still achieving warpage control through thermal management.
4Measurement precision
If infrared camera is used for temperature monitoring during LAB, then temperature measurement is attempted, but monitoring becomes impractical due to warpage and heat interference
Solution Approach 1:
The susceptor serves as a thermal mediator that can be independently monitored. Since the susceptor is separate from the device, temperature monitoring of the susceptor provides indirect but accurate measurement of the bonding interface temperature without being affected by device warpage or internal heat generation, making monitoring practical and reliable.
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 PI tape significantly reduces warpage and stress on semiconductor devices during LAB, enabling more efficient bonding with improved alignment and temperature monitoring, resulting in higher processing units per hour compared to compression LAB methods.
Implementation Method 1
laser emission is projected to the bonding surface to melt fusible material
Implementation Method 2
the fusible material resolidifies and bonds the semiconductor device to the substrate
Data Source
AI summary
A semiconductor device has a semiconductor die and a support tape disposed over a back surface of the semiconductor die opposite an active surface of the semiconductor die. A portion of the back surface of the semiconductor wafer is removed to reduce its thickness. The semiconductor die is part of a semiconductor wafer, and the wafer is singulated to provide the semiconductor die with the support tape disposed on the back surface of the semiconductor die. The support tape can be a polyimide tape. A dicing tape is disposed over the support tape. The semiconductor die is disposed over a substrate. A laser emission is projected onto the semiconductor die to bond the semiconductor die to the substrate. The support tape provides stress relief to avoid warpage of the semiconductor die during the laser emission. The support tape is removed from the back surface of the semiconductor die.