Semiconductor Package Solder Bonding With Reflective Stencil Heating
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Solution Overview
Problem
Laser-assisted bonding (LAB) in semiconductor devices induces stress and damage, leading to low reliability.
Innovation Solution
A method involving the use of a stencil with openings aligned with contact pads, where solder bumps are formed and irradiated with a homogenized laser beam, with the stencil reflecting most of the laser energy to reduce heat transfer and stress in the semiconductor package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser-assisted bonding is used to bond semiconductor device to substrate, then bonding efficiency is improved, but stress and damages are induced in the semiconductor device
Solution Approach 1:
The laser beam is segmented into multiple independent laser sources arranged in an array, allowing selective irradiation of different regions. This segmentation enables precise control of heating zones, reducing stress propagation to the semiconductor device while maintaining bonding efficiency through parallel processing of multiple contact pads.
Solution Approach 2:
Different regions receive different laser intensities and durations - the contact pad regions receive high intensity for rapid heating and bonding, while the semiconductor device regions receive reduced or no laser exposure. This local quality differentiation achieves effective bonding without inducing stress and damages in the semiconductor device.
2Speed
If conventional laser beam irradiation is applied to solder bumps, then bonding speed is improved, but heat transfer causes stress and warpage in the semiconductor package
Solution Approach 1:
The laser beam is divided into multiple segmented beams that can be independently controlled. Each beam targets specific contact pad areas, enabling rapid localized heating for bonding while avoiding excessive heat accumulation in the semiconductor package, thus reducing stress and warpage.
Solution Approach 2:
The segmented laser beams are activated in a periodic or sequential manner rather than simultaneously, allowing controlled heat distribution. This periodic action enables rapid bonding at each contact pad while providing thermal management across the entire package, reducing overall stress and warpage.
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
Reduces stress and warpage in the semiconductor package, enhancing reliability by minimizing heat generation and potential damage to electronic components.
Implementation Method 1
irradiating the plurality of solder bumps with a homogenized laser beam to form a solder interconnection
Implementation Method 2
irradiating the bonding region with a homogenized laser beam to melt the solder bump
Implementation Method 3
the stencil reflecting most of the laser energy to reduce heat transfer and stress in the semiconductor package
Data Source
AI summary
A semiconductor device and a method for forming the same are provided. The method includes: providing a semiconductor package including a plurality of contact pads formed on a surface of the semiconductor package; providing a stencil having a plurality of openings; disposing the stencil on the surface of the semiconductor package with the plurality of openings aligned with the plurality of contact pads respectively; forming a plurality of solder bumps on the plurality of contact pads and in the plurality of openings, respectively; and irradiating the plurality of solder bumps with a homogenized laser beam to form a solder interconnection between each of the plurality of solder bumps and a respective one of the plurality of contact pads.