PIC Chip Facet Preparation Using Laser Stealth Dicing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for preparing facets of photonic integrated circuits (PICs) face challenges in achieving precise location accuracy, low surface roughness, and high flatness, especially at shorter wavelengths, due to limitations in mechanical cleaving, polishing, saw-based dicing, and etching techniques.
Innovation Solution
The use of laser-based stealth dicing, which involves forming modified layers within the wafer using transmissive laser beams and expanding a dicing tape to define facets, allowing for high precision and low-loss coupling, and enabling wafer-scale PIC chip facet preparation with minimal surface damage and debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical cleaving or saw-based dicing is used to prepare PIC facets, then the fabrication process is simple and fast, but the location accuracy and surface roughness are insufficient
Solution Approach 1:
The patent replaces mechanical dicing and cleaving methods with a laser-based process. A laser beam is used to write modified layers within the wafer substrate, which are then separated by expanding a dicing tape. This substitution of mechanical processes with optical processes enables precise facet definition and low surface roughness while maintaining fabrication efficiency.
Solution Approach 2:
The patent changes the physical state and properties of the wafer material by using laser energy to create modified layers with different refractive indices and mechanical properties. These modified layers serve as precise guides for facet formation, enabling high-precision facet preparation without traditional mechanical contact.
2Loss of energy
If traditional dicing methods are used, then the process is straightforward, but substrate 'shelves' are created and insertion losses increase
Solution Approach 1:
By using laser-based writing of modified layers instead of mechanical sawing, the patent eliminates the creation of substrate shelves that cause insertion losses. The laser process creates clean, precise modifications within the substrate that do not generate the mechanical debris and uneven surfaces characteristic of traditional dicing methods.
Solution Approach 2:
The patent converts the laser's energy into a beneficial modification of the substrate material, creating controlled modified layers that guide precise facet formation. This transforms what would be destructive mechanical cutting into a controlled optical process that eliminates harmful substrate shelves while reducing insertion losses.
3Manufacturing precision
If mechanical polishing is used to improve facet flatness, then surface flatness improves, but the process time increases and surface damage may occur
Solution Approach 1:
The patent performs preliminary action by using the laser to write modified layers that precisely define the facet geometry before any separation or polishing steps. This pre-definition of the facet structure through optical modification eliminates the need for extensive mechanical polishing, achieving high flatness while reducing processing time and avoiding surface damage from mechanical contact.
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 results in PICs with accurate and precise facet sidewall angles, low surface roughness, and high flatness, suitable for applications like quantum computing and bio-sensing, particularly beneficial for shorter-wavelength PICs by eliminating substrate 'shelves' and reducing insertion losses.
Implementation Method 1
performing a first laser processing step to form a modified layer by applying at least one laser beam of a wavelength that has transmissivity through the wafer along a first projected dicing line
Implementation Method 2
applying at least one laser beam of a wavelength that has transmissivity through the wafer
Implementation Method 3
expanding the dicing tape in a second direction to divide the wafer from the modified layer along at least the first projected dicing line and the second projected dicing line into PIC chips
Data Source
AI summary
Aspects of the present disclosure relate generally to systems and methods for use in the implementation and/or operation of preparing photonic integrated circuits (PICs). Specifically, the method include coupling a dicing tape to a first side of a wafer. The method also includes performing a first laser processing step to form a modified layer by applying at least one laser beam of a wavelength that has transmissivity through the wafer along a first projected dicing line to define a first facet and performing a second laser processing step to form the modified layer by applying the at least one laser beam to the wafer along a second projected dicing line to define a second facet. The method further includes expanding the dicing tape to divide the wafer from the modified layer along at least the first projected dicing line and the second projected dicing line into PIC chips.