Silicon Photonics Coupling Structure Using Etch Stop Layer
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Solution Overview
Problem
Silicon photonics coupling faces challenges in achieving efficient optical interconnection between optical fibers and silicon photonics devices due to issues with etching profiles that can degrade optical coupling and lead to overetching, affecting the performance and reliability of the connection.
Innovation Solution
The use of a dielectric etch stop layer, specifically silicon nitride or silicon oxynitride, is introduced to control the vertical cross-sectional profile of openings through a passivation dielectric layer over a silicon grating structure, preventing overetching and optimizing the etch profile for improved optical coupling by varying the etch resistance around the opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching is used to form openings through the passivation dielectric layer, then the etching process can be completed, but overetching occurs which degrades the vertical cross-sectional profile and affects optical coupling performance
Solution Approach 1:
An etch stop layer is formed at the interface between the passivation dielectric layer and the underlying layer before etching the opening. This preliminary structure prevents overetching by stopping the etching process when it reaches the etch stop layer, thereby maintaining the vertical cross-sectional profile and ensuring reliable optical coupling performance
Solution Approach 2:
The etch stop layer acts as an intermediary layer between the passivation dielectric layer and the underlying layer. It mediates the etching process by providing a controlled stopping point that prevents direct contact between the etchant and the underlying layer, thus avoiding profile degradation while allowing complete opening formation
2Ease of manufacture
If the etching process is extended to ensure complete opening formation, then the opening can be fully formed, but the etch profile degrades due to overetching
Solution Approach 1:
The etch stop layer is preliminarily formed to define the maximum etching depth. This allows the etching process to proceed completely to form the opening while automatically stopping before degrading the etch profile, as the etch stop layer provides a physical barrier that prevents further etching
3Device complexity
If no etch stop layer is used, then the device structure remains simple, but overetching occurs which affects optical coupling efficiency
Solution Approach 1:
The etch stop layer serves as a simple intermediary structure that mediates between the passivation dielectric layer and the underlying layer. It provides the necessary function of preventing overetching and maintaining optical coupling efficiency with minimal added complexity, as it is a single layer that can be integrated into existing fabrication processes
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 solution enhances the etch resistance and minimizes optical interference, leading to more reliable and efficient optical coupling between silicon photonics devices and optical fibers, thereby improving the performance and stability of the interconnection.
Implementation Method 1
The at least one dielectric etch stop layer 66 is over the at least one dielectric material layer 60 and includes at least one dielectric material selected from silicon nitride and silicon oxynitride. An opening 69 is formed through an unmasked portion of the passivation dielectric layer 70 by performing an anisotropic etch process that etches the dielectric material selective to silicon nitride or silicon oxynitride
Data Source
AI summary
An optical structure may be provided by forming a silicon grating structure over a dielectric material layer, depositing at least one dielectric material layer over the silicon grating structure, and depositing at least one dielectric etch stop layer over the at least one dielectric material layer. The at least one dielectric etch stop layer includes at least one dielectric material selected from silicon nitride and silicon oxynitride. A passivation dielectric layer may be formed over the at least one dielectric etch stop layer, and a patterned etch mask layer may be formed over the passivation dielectric layer. An opening may be formed through an unmasked portion of the passivation dielectric layer by performing an anisotropic etch process that etches the dielectric material selective to a silicon nitride or silicon oxynitride using the patterned etch mask layer as a masking structure. The at least one etch mask layer minimizes overetching.