Wafer Separation via Pilot Groove Alignment and Non-Sequential Breaking
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Solution Overview
Problem
Current methods for dicing semiconductor wafers, such as those used for light emitting diodes (LEDs), face challenges in achieving high yields due to misalignment and sidewall offsets during the separation process, which can result in damaged devices and reduced efficiency.
Innovation Solution
The method involves scribing a shallow pilot groove for alignment correction followed by a deeper singulation groove to ensure precise separation, and employing non-sequential breaking patterns to minimize sidewall offsets and improve yield, along with using location-specific best-fit line alignment algorithms for irregular arrays of LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single deep groove is scribed for wafer separation, then the separation depth is sufficient, but alignment precision deteriorates due to lack of reference correction
Solution Approach 1:
The singulation groove is divided into two segments: a shallow pilot groove (first groove) that serves as an alignment reference, and a deeper singulation groove (second groove) that provides sufficient separation depth. This segmentation allows the alignment function and separation function to be performed by different groove portions, resolving the contradiction between alignment precision and separation depth.
Solution Approach 2:
The shallow pilot groove is scribed first to establish an alignment reference before scribing the deeper singulation groove. This preliminary action creates a reference feature that enables accurate positioning and alignment correction, ensuring that the subsequent deep groove can be precisely positioned without compromising alignment accuracy.
2Ease of manufacture
If sequential breaking is used to separate the wafer, then the process is simple, but sidewall offsets increase causing device damage
Solution Approach 1:
The breaking process transitions from a static sequential approach to a dynamic non-sequential approach where breaking operations are performed in multiple passes with varying patterns. The method alternates between breaking different sections of the wafer, allowing stress distribution and sidewall offset compensation, thereby reducing device damage while maintaining process feasibility.
3Measurement precision
If alignment checking is performed continuously during grooving, then alignment accuracy is maintained, but processing time increases
Solution Approach 1:
Alignment checking is performed at specific predetermined locations rather than continuously throughout the entire grooving process. This preliminary alignment verification at key points is sufficient to ensure overall alignment accuracy while significantly reducing the time spent on alignment checks compared to continuous monitoring.
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 precision and efficiency of wafer separation, reducing sidewall offsets and improving yield by allowing for accurate alignment and controlled breaking, thereby minimizing device damage and increasing the effectiveness of the dicing process.
Implementation Method 1
a laser is often used in the process of dicing a semiconductor wafer such that individual devices (or dies) manufactured from the semiconductor wafer are separated from each other. The dies on the wafer are separated by streets and the laser may be used to cut the wafer along the streets.
Data Source
AI summary
A method of separating a wafer including rows of light emitting devices is described. Dicing streets are provided on the wafer such that a respective one of the dicing streets is provided between each of the rows of light emitting devices on the wafer. The wafer is broken along a first one of the dicing streets to separate a first portion of the wafer from a remaining portion of the wafer. The first portion of the wafer includes more than one of the rows of light emitting devices. The first portion of the wafer is broken along a second one of the dicing streets to separate a second portion of the wafer from the first portion of the wafer.