Wafer Singulation with Multi-Pass Laser Grooves and Wide Sawing
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Solution Overview
Problem
The increasing complexity of integrated circuit packages, which include multiple device dies and different technologies, poses challenges in efficient singulation processes that require precise removal of dielectric layers without penetrating the semiconductor substrate.
Innovation Solution
A method involving multiple narrow laser grooving processes with overlapping paths, followed by wide blade sawing, to create combined grooves that allow for accurate separation of packages without damaging the semiconductor substrate, combined with a defocus laser cleaning process to remove residue portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single narrow laser grooving process is used, then the groove width is sufficient for precision, but the singulation efficiency is low and the process time is long
Solution Approach 1:
The singulation process is divided into multiple sequential laser grooving passes, where each pass creates a portion of the final groove. The first pass creates an initial groove, the second pass widens it, and the third pass completes the separation. This segmentation allows each pass to be optimized for its specific function while collectively achieving both precision and efficiency
Solution Approach 2:
The laser grooving is performed in periodic intervals with multiple passes at different positions. The laser beam is systematically repositioned to create overlapping grooves that progressively widen the separation channel, transforming a continuous precision task into discrete periodic actions that improve overall throughput
2Productivity
If wide blade sawing is used directly, then the singulation speed is high, but the dielectric layers may be damaged or the substrate may be penetrated
Solution Approach 1:
Multiple narrow laser grooving passes are performed before the final wide blade sawing operation. These preliminary passes create a pre-formed groove structure that guides the blade sawing process, ensuring that the blade follows a precise path through the dielectric layers without deviating or causing damage to surrounding structures
Solution Approach 2:
The multiple laser grooving passes create a cushioning effect by progressively removing material and creating a controlled groove geometry. This pre-conditioning of the material structure absorbs the mechanical stress of the subsequent blade sawing operation, preventing unintended penetration or damage to the semiconductor substrate
3Length of stationary object
If multiple laser grooving processes with overlapping paths are used, then the groove width is increased for better sawing, but the process complexity increases
Solution Approach 1:
The same laser grooving apparatus and beam parameters are used across all three passes, with only the positioning coordinates changing. This universal approach allows the system to create different groove widths and depths using identical equipment settings, reducing the need for multiple specialized devices or complex parameter adjustments
Solution Approach 2:
The laser grooving process is replicated three times with identical parameters but different starting positions. Each pass copies the same grooving pattern and energy distribution, creating consistent overlapping grooves that systematically build up to the final desired width without requiring unique process designs for each pass
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 enhances the accuracy and efficiency of singulation by widening the grooves for precise wide sawing, preventing damage to dielectric layers and ensuring the process stops at the semiconductor substrate, thereby improving yield and reducing costs.
Implementation Method 1
performing a first plurality of laser grooving processes on a scribe line of a substrate to form a first combined groove; performing a second plurality of laser grooving processes on the scribe line of the substrate to form a second combined groove
Implementation Method 2
performing a defocus laser cleaning process to remove residue portions
Data Source
AI summary
A method includes performing a first plurality of laser grooving processes on a scribe line of a wafer to form a first combined groove, and performing a second plurality of laser grooving processes on the scribe line of the wafer to form a second combined groove. A first sawing process is performed on the scribe line of the wafer. The first sawing process is performed in a part of the scribe line between the first combined groove and the second combined groove. A second sawing process is performed to saw through the wafer in the scribe line. The second sawing process separates a first device die and a second device die on opposing sides of the scribe line from each other.