Optical connectivity has the potential to outperform copper-based TSVs in terms of bandwidth at the cost of more complexity due to the required electro-optical and opto-electrical conversion. The continuously increasing demand for higher bandwidth pushes the breakeven point for a profitable operation to shorter distances. To integrate an optical communication network in a 3D-chip-stack optical through-silicon vertical VIAs (TSV) are required. While the necessary effort for the electrical/optical and vice versa conversion makes it hard to envision an on-chip optical interconnect, a chip-to-chip optical link appears practicable. In general, the interposer offers the potential advantage to realize electro-optical transceivers on affordable expense by specific, but not necessarily CMOS technology. We investigated the realization and characterization of optical interconnects as a polymer based waveguide in high aspect ratio (HAR) TSVs proved on waferlevel.
To guide the optical field inside a TSV as optical-waveguide or fiber, its core has to have a higher refractive index than the surrounding material. Comparing different material / technology options it turned out that thermal grown silicon dioxide (SiO2) is a perfect candidate for the cladding (nSiO2 = 1.4525 at 850 nm). In combination with SiO2 as the adjacent polymer layer, the negative resist SU-8 is very well suited as waveguide material (nSU-8 = 1.56) for the core. Here, we present the fabrication of an optical polymer based multimode waveguide in TSVs proved on waferlevel using SU-8 as core and SiO2 as cladding. The process resulted in a defect-free filling of waveguide TSVs with SU-8 core and SiO2 cladding up to aspect ratio (AR) 20:1 and losses less than 3 dB.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:35138 |
| Date | 06 September 2019 |
| Creators | Killge, S., Charania, S., Richter, K., Neumann, N., Al-Husseini, Z., Plettemeier, D., Bartha, J. W. |
| Publisher | SPIE |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:conferenceObject, info:eu-repo/semantics/conferenceObject, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.1117/12.2265168, info:eu-repo/grantAgreement/European Social Fund/Atto3D - Communication infrastructure for atto-networks in 3DChip-Stacks/100238554/, info:eu-repo/grantAgreement/European Social Fund/3DCSI - 3D Chip Stack Intraconnects/100098177/ |
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