Wafer Division via Laser Breaking of Test Metal Patterns
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The presence of test metal patterns on semiconductor wafers interferes with laser beam processing, leading to uneven deteriorated layers and potential device contamination during wafer division, risking the leakage of proprietary information.
Innovation Solution
A method involving a pulse laser beam with specific parameters (1,064 nm wavelength, 20-80 KHz repetition frequency, and 0.05-0.2 W average output) is applied from the rear surface to break test metal patterns and form deteriorated layers along the streets, allowing for clean division without breaking the patterns, thus preventing device constitution detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is applied from the rear surface to form deteriorated layers uniformly, then the uniformity of deteriorated layers is improved, but the test metal patterns are broken like saw teeth causing contamination and device quality reduction
Solution Approach 1:
The patent applies a preliminary action by first forming break lines in the test metal patterns using a laser beam with focal point near the patterns, before forming the deteriorated layers. This preliminary breaking prevents the patterns from shattering during subsequent division, eliminating contamination while maintaining uniform deteriorated layer formation.
Solution Approach 2:
The patent segments the laser processing into two distinct stages: first creating break lines in the test metal patterns, then forming deteriorated layers in the wafer substrate. This segmentation allows each process to be optimized independently, preventing pattern damage while achieving uniform layer formation.
2Reliability
If test metal patterns remain intact on the wafer, then device function testing can be performed, but the constitution of devices can be detected from the metal patterns leading to company secret leakage
Solution Approach 1:
The patent performs preliminary breaking of test metal patterns before wafer division, destroying their functionality to prevent information leakage about device constitution, while still allowing device testing to be completed beforehand.
Solution Approach 2:
The patent converts the harmful effect of broken test metal patterns (which would normally cause contamination) into a beneficial outcome by first breaking the patterns to prevent information leakage, then using the same breaking mechanism to prevent subsequent pattern shattering during division, thus eliminating contamination risk while maintaining security.
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 effectively breaks test metal patterns without causing them to shatter like a saw, ensuring the integrity of the devices and maintaining confidentiality by destroying the patterns' functionality, allowing for uniform and secure wafer division.
Implementation Method 1
applying a pulse laser beam having permeability to the wafer from the rear surface of the wafer with its focal point set to a position near the test metal patterns along the streets
Implementation Method 2
applying a pulse laser beam having permeability to the wafer from the rear surface of the wafer with its focal point set to a position above the break lines in the inside of the wafer along the streets
Data Source
AI summary
A method of dividing a wafer having a plurality of devices, which are formed in a plurality of areas sectioned by streets formed in a lattice pattern on the front surface and test metal patterns which are formed on the streets, having a metal pattern breaking step for forming a break line in the test metal patterns by applying a pulse laser beam having permeability to the wafer to the rear surface of the wafer with its focal point set near the test metal patterns; a deteriorated layer forming step for forming a deteriorated layer along the streets above the break lines in the inside of the wafer by applying a pulse laser beam having permeability to the wafer to the rear surface of the wafer with its focal point set to a position above the break lines in the inside of the wafer; and a dividing step.