Multi-Pulse Laser Substrate Separation for Semiconductor Dice
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Solution Overview
Problem
The existing methods for separating a substrate from semiconductor structures during the fabrication of semiconductor dice often result in damage to the structures, such as cracking and peeling, due to the forces applied during the separation process.
Innovation Solution
A method involving the application of multiple laser pulses to selectively separate the substrate from semiconductor structures, with the first pulse applied to a larger area and the second pulse to a smaller area proximate to each die, minimizing damage and allowing for the formation of intermediate structures to protect the dice during separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single high-energy laser pulse is used to separate the substrate from semiconductor structures, then the separation process is fast and efficient, but the semiconductor structures suffer from cracking and peeling damage
Solution Approach 1:
The single high-energy laser pulse is divided into multiple sequential pulses with different parameters. The first pulse uses lower energy to initiate separation, while subsequent pulses progressively increase energy to complete the separation. This segmentation prevents sudden high-energy impact that causes cracking and peeling, while maintaining overall separation efficiency.
Solution Approach 2:
The first laser pulse performs preliminary separation by breaking the initial bond between the substrate and semiconductor structures. This preliminary action creates a controlled separation interface that reduces stress concentration, allowing subsequent pulses to complete the separation without causing damage to the semiconductor structures.
2Reliability
If laser parameters (area, power, duration) are increased to ensure complete separation, then separation completeness is improved, but damage to semiconductor structures increases
Solution Approach 1:
The separation process uses periodic laser pulses with varying parameters rather than a single continuous high-energy pulse. The pulses are applied in sequence with the first pulse having lower energy parameters to start separation, followed by subsequent pulses that progressively increase in energy. This periodic action ensures complete separation while distributing energy input to prevent localized overheating and damage.
Solution Approach 2:
The laser parameters (area, power, duration) are dynamically changed across multiple pulses. The first pulse uses smaller area and lower power, while subsequent pulses gradually increase these parameters. This parameter progression ensures that separation is initiated gently and completed thoroughly, achieving reliable separation without excessive damage to the semiconductor structures.
3Area of stationary object
If a larger laser pulse area is used to cover the entire substrate, then separation coverage is improved, but energy distribution becomes less precise and damage increases
Solution Approach 1:
The laser pulses are applied with different area sizes tailored to specific regions. The first pulse uses a smaller area focused on the interface region to initiate separation, while subsequent pulses progressively expand the area to cover more of the substrate. This local quality approach ensures precise energy concentration where needed while maintaining broader coverage for complete separation.
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 reduces damage to semiconductor structures during substrate separation, enabling the successful fabrication of semiconductor dice with minimized cracking and peeling, while allowing for precise control of the separation process.
Implementation Method 1
separating the substrate from the semiconductor structures by applying a first laser pulse and a second laser pulse to each semiconductor die on the substrate
Data Source
AI summary
A method for fabricating semiconductor dice includes the steps of providing a wafer assembly having a substrate and semiconductor structures on the substrate; and defining the semiconductor dice on the substrate. The method also includes the step of separating the substrate from the semiconductor structures by applying a first laser pulse to each semiconductor die on the substrate having first parameters selected to break an interface between the substrate and the semiconductor structures and then applying a second laser pulse to each semiconductor die on the substrate having second parameters selected to complete separation of the substrate from the semiconductor structures. The method can also include the steps of forming one or more intermediate structures between the semiconductor dice on the substrate configured to protect the semiconductor dice during the separating step.