BEOL Cladding Structure for Photonics Chip Light Confinement
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Solution Overview
Problem
The need for increased bandwidth in fiber optic network links and the challenge of integrating optical components with electronic components in integrated circuit chips for high-speed signaling and sensing applications, particularly in silicon photonics, has not been adequately addressed by existing technologies.
Innovation Solution
A cladding structure is introduced in the back end of line (BEOL) of monolithic photonics chips, comprising a first cladding structure covering optical components and a second cladding structure with a different material, which provides electrical isolation and light confinement, while also serving as an etch stop layer to prevent over-etching and enhance integration with interlayer dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-material cladding structure is used for optical components, then the manufacturing process is simple, but light confinement is insufficient and electrical isolation is compromised
Solution Approach 1:
The patent employs a dual-layer cladding structure consisting of a first cladding layer (e.g., silicon oxide) and a second cladding layer (e.g., silicon nitride) with different material properties. The first layer provides electrical isolation and etch stop functionality, while the second layer provides optical confinement with higher refractive index. This composite structure resolves the contradiction by combining materials with complementary properties to simultaneously achieve both electrical isolation and light confinement.
Solution Approach 2:
The cladding structure is segmented into distinct functional layers: a first cladding layer positioned adjacent to the optical component for electrical isolation and etch protection, and a second cladding layer for optical confinement. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between manufacturing simplicity and performance requirements.
2Reliability
If multiple cladding layers with different materials are used, then light confinement and electrical isolation are improved, but the manufacturing complexity increases
Solution Approach 1:
The first cladding layer serves multiple functions simultaneously: it provides electrical isolation between the optical component and underlying structures, acts as an etch stop layer to prevent over-etching during fabrication, and serves as a foundation for the second cladding layer. This multi-functionality reduces the need for additional separate layers, thereby limiting the increase in manufacturing complexity while maintaining improved light confinement and electrical isolation.
Solution Approach 2:
The patent merges the electrical isolation function and etch stop function into the first cladding layer, rather than requiring separate dedicated layers for each function. This merging approach consolidates the structure and reduces fabrication steps, mitigating the complexity increase that would otherwise result from adding multiple specialized layers.
3Reliability
If the cladding structure extends deep into interlayer dielectric levels, then electrical isolation is enhanced, but the risk of over-etching and damage to underlying structures increases
Solution Approach 1:
The first cladding layer is deposited beforehand to serve as a protective etch stop layer before subsequent etching processes are performed. This preliminary action ensures that even if etching processes extend deeper than intended, the first cladding layer prevents damage to the optical component and underlying structures, thereby enabling enhanced electrical isolation without increasing over-etching risk.
Solution Approach 2:
The first cladding layer acts as a cushioning protective layer that absorbs the harmful effect of potential over-etching. By positioning this layer between the optical component and the etching process, it provides a safety margin that protects critical structures from damage while allowing the cladding structure to extend sufficiently for electrical isolation.
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 solution enhances the integration of optical and electronic components, improves light confinement, and prevents over-etching, thereby supporting high-speed signaling and sensing applications with improved system performance and scalability.
Implementation Method 1
The second cladding structure provides electrical isolation and light confinement
Implementation Method 2
The second cladding structure provides electrical isolation and light confinement
Data Source
AI summary
IC chips for photonics applications are disclosed. An example IC chip includes a substrate, an optical component above the substrate, and a first connection level above the substrate. The first connection level includes the optical component and a first cladding structure, in which the optical component is covered by the first cladding structure. The IC chip also includes a second connection level on the first connection level. The second connection level includes a first interlayer dielectric material. The IC chip further includes a second cladding structure directly above the optical component. The second cladding structure has at least a section within the second connection level. The second cladding structure is on the first cladding structure. The second cladding structure is laterally adjacent to and in direct contact with the first interlayer dielectric material. The second cladding structure includes a material different from the first interlayer dielectric material.