Passive Alignment Surfaces for Photonic Die Substrate Bonding
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Solution Overview
Problem
The challenge in silicon photonics is the need for highly accurate alignment of optical waveguides between different semiconductor substrates, such as silicon and indium phosphide or gallium arsenide, to achieve efficient optical coupling, which is currently time-consuming and costly using precision micromanipulators.
Innovation Solution
The use of passive alignment surfaces on photonic dies and receiving substrates, formed using lithography and etching techniques, allows for sub-micron accurate alignment in all six degrees of freedom without the need for precision micro-positioning manipulators, using a mesa with three alignment surfaces that contact complementary surfaces on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If precision micromanipulators and active feedback are used to position substrates, then alignment accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The alignment surfaces on the photonic die and receiving substrate automatically guide each other into the correct relative position through passive mechanical contact, eliminating the need for external micromanipulators and feedback control systems. The structures themselves perform the alignment function.
Solution Approach 2:
The patent replaces complex active mechanical positioning systems (micromanipulators with feedback control) with a simple passive mechanical alignment system using complementary alignment surfaces that self-align through contact.
2Manufacturing precision
If precision micromanipulators are used for substrate positioning, then alignment accuracy is improved, but manufacturing time increases
Solution Approach 1:
The alignment process becomes automated and self-executing through the complementary alignment surfaces that automatically position the substrates correctly when brought into contact, eliminating time-consuming manual micromanipulator operations.
Solution Approach 2:
The alignment surfaces are pre-formed on the substrates during fabrication, so that when the substrates are brought together, alignment is automatically achieved without requiring time-consuming positioning adjustments during assembly.
3Manufacturing precision
If active feedback alignment is used, then alignment accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The alignment function is built into the substrates themselves through lithographically-defined alignment surfaces, eliminating the need for expensive micromanipulator equipment and active feedback control systems, thereby reducing manufacturing costs.
Solution Approach 2:
The patent replaces expensive active mechanical positioning equipment with inexpensive passive alignment surfaces that can be formed using standard lithography and etching processes already present in the manufacturing line.
Data Source
AI summary
Structures and methods for passively aligning a photonic die with a receiving substrate are described. Three alignment surfaces, having dimensions greater than a desired alignment accuracy, may be formed on the photonic die and used to passively and accurately align the photonic die to a receiving substrate in six degrees of freedom. Two of the three alignment surfaces on the photonic die may be formed in a single mask-and-etch process, while the third alignment surface may require no patterning or etching. Three complementary alignment surfaces on the receiving substrate may be formed in a single mask-and-etch process.