Wafer Singulation by Front-Side Trenches for Accurate LED Chip Cleavage
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Solution Overview
Problem
Conventional wafer singulation methods, such as laser dicing, face issues with misalignment of back side grooves relative to front side grooves, leading to abnormal oblique cleavage and reduced production yield due to the use of intermediate steps like back side laser scribing and dicing, which increase costs and time consumption.
Innovation Solution
A wafer singulating method involving deep scribing on the front side to form intersecting trenches, followed by cleaving the back side along these trenches in multiple directions towards the center, eliminating the need for back side laser scribing and dicing, thereby ensuring accurate alignment and reducing the risk of oblique cleavage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If back side laser scribing and dicing are performed using intermediate reference lines, then the wafer can be divided into individual chips, but misalignment occurs between back side grooves and front side grooves causing oblique cleavage and reduced manufacturing precision
Solution Approach 1:
The patent removes the intermediate back side laser scribing and dicing steps from the conventional process. Instead of using back side reference lines as intermediates, the invention directly uses front side grooves as the sole reference for back side cleavage, eliminating the source of misalignment between different reference systems.
Solution Approach 2:
The front side grooves serve multiple functions: they act as both the primary reference for back side cleavage and the direct guide for chip separation. This universal reference system eliminates the need for separate back side reference lines, ensuring consistent alignment throughout the process.
2Productivity
If multiple intermediate steps are used for wafer singulation, then chip separation can be achieved, but production time and processing costs increase
Solution Approach 1:
The patent extracts and eliminates the time-consuming intermediate steps of back side laser scribing and dicing. By proceeding directly from front side groove formation to back side cleavage, the process removes unnecessary processing stages that contribute to extended production time.
Solution Approach 2:
The invention skips the intermediate back side reference line creation and dicing steps, rushing directly from front side grooving to back side cleavage. This streamlined approach maintains essential processing while eliminating redundant operations that slow down production.
3Ease of manufacture
If conventional laser dicing with multiple steps is used, then wafer singulation can be performed, but the process complexity and cost increase
Solution Approach 1:
The front side grooves perform multiple functions simultaneously: they serve as the reference for back side cleavage and as the direct separation guide. This universal reference approach simplifies the process by eliminating the need for separate back side reference systems while maintaining high alignment accuracy.
Solution Approach 2:
The patent merges the reference function and separation function into a single system - the front side grooves. Instead of having separate reference lines and cutting paths, the invention combines these functions into one unified groove structure that guides both alignment and separation operations.
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 method improves the alignment and quality of singulated chips by ensuring perpendicular cleavage, reduces defects, and increases production yield while minimizing processing steps and costs.
Implementation Method 1
deep scribing the wafer product with a laser along the scribe lines from the front side of the wafer product to form a plurality of intersecting trenches on the front side of the wafer product
Data Source
AI summary
A wafer singulating method includes: providing a wafer product having front and back sides the front side being formed with scribe lines; deep scribing with a laser along the scribe lines on the front side to form a plurality of intersecting trenches; and cleaving the back side along the trenches on the front side. The cleaving of the back side proceeds in different directions each of which is directed to a center of the wafer product from a periphery of the wafer product. The cleaving in each of the directions proceeds along the trenches one after the other from one of the trenches nearest to the periphery of the wafer product and ceases near or at the center.