Wafer Dicing with Multi-Pulse Lasers for Low-Damage Separation
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Solution Overview
Problem
Conventional laser dicing methods cause damage to semiconductor devices by thermally reflowing not only the cut areas but also the surrounding areas, leading to partial device damage.
Innovation Solution
A wafer dicing method using a multiple pulse laser beam with decreasing peak powers and controlled arrival time intervals forms inner cracks in the scribe lane region, allowing precise separation of semiconductor devices without damaging surrounding areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is irradiated to cut the wafer, then the wafer is separated into individual devices, but the surrounding areas are thermally reflowed causing device damage
Solution Approach 1:
The laser beam is divided into multiple sub-laser beams that are spatially separated and focused at different depths within the wafer. This segmentation allows each sub-beam to target specific regions (scribe lane at different depths) without overlapping thermal zones, preventing collateral damage to surrounding devices while maintaining cutting efficiency
Solution Approach 2:
The invention transitions from a single-plane cutting approach to a three-dimensional cutting strategy by focusing multiple sub-laser beams at different depths within the wafer thickness. This depth-dimension utilization enables precise scribe lane removal without thermal interference to surface-mounted devices, resolving the contradiction between cutting effectiveness and device safety
2Productivity
If high peak power is used to form cracks efficiently, then the dicing speed increases, but the thermal damage to surrounding areas increases
Solution Approach 1:
Each sub-laser beam is assigned a specific local function: the first sub-beam targets the scribe lane surface and upper layers, while the second sub-beam targets deeper regions. This local quality differentiation allows optimized peak power delivery to specific zones without causing widespread thermal damage, maintaining both speed and safety
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 method enhances the reliability of semiconductor device separation by minimizing damage to surrounding areas during the dicing process, ensuring high precision and efficiency.
Implementation Method 1
forming a plurality of inner cracks in the scribe lane region of the wafer by repeatedly irradiating a multiple pulse laser beam that includes a plurality of sub-laser beams along the scribe lane region
Implementation Method 2
a workpiece can be thermally reflowed by irradiating laser light in a wavelength band having a high absorptance to the workpiece to cut the workpiece
Implementation Method 3
the plurality of sub-laser beams have decreasing peak powers, and separating the plurality of semiconductor devices from each other along the plurality of inner cracks
Data Source
AI summary
A wafer dicing method includes preparing a wafer that includes a plurality of device forming regions and a scribe lane region that separates the plurality of device forming regions, forming a plurality of semiconductor devices in the plurality of device forming regions of the wafer, respectively, forming a plurality of inner cracks in the scribe lane region of the wafer by repeatedly irradiating a multiple pulse laser beam that includes a plurality of sub-laser beams along the scribe lane region, wherein the plurality of sub-laser beams have decreasing peak powers, and separating the plurality of semiconductor devices from each other along the plurality of inner cracks.