Founded in 2020 and based in the heart of Paris, C12’s mission is to be at the center of one of the biggest technological breakthroughs of the century and change the course of history by building a universal quantum computer.

At C12, we believe that achieving a true breakthrough in quantum computing requires rethinking the fundamentals. That’s why our founders—deeply rooted in academic and engineering excellence—have chosen carbon nanotubes as the building blocks of our quantum processors. This ultra-pure material dramatically reduces error rates, boosts performance, and minimizes hardware overhead—key ingredients for scalable, fault-tolerant quantum computing. By crafting a unique approach that scales, we aim to revolutionize quantum computing just as silicon transformed classical computing.

Since our founding, we’ve raised over €25 million in funding, published 11 scientific papers, and secured 8 patents. Today, our fast-growing team of 90 people, including over 20 PhDs, has over 20 nationalities represented. We have our own cutting-edge lab spaces in Paris' historic Panthéon district, where scientists, engineers, and innovators work side-by-side to tackle some of the most exciting technical challenges of our time.

If you're passionate about shaping the future of quantum technology and want to make a real impact, C12 offers a unique environment to grow, learn, and innovate.

We are seeking a 3D Integration Engineer to develop advanced packaging and heterogeneous-integration technologies for scalable quantum-computing hardware.

You will design and optimize interconnects between quantum devices, control electronics, photonic components, and cryogenic systems while maintaining signal integrity, thermal performance and reliability.

Key responsibilities:

You will develop 2.5D and 3D integration architectures for quantum processors and supporting electronics.

You will design interposers, through-silicon vias, micro-bumps, hybrid bonds, redistribution layers, and chiplet interfaces.

You will integrate our QPU with other chip modality with cryogenic CMOS, RF/microwave circuitry, photonics, MEMS, and packaging substrates.

You will perform electrical, electromagnetic, mechanical, and thermal simulations.

You will define fabrication flows and design rules with foundries, packaging partners, and internal process teams.

You will develop test vehicles and perform experimental measurements on those fabricated devices, analyze experimental data to improve yield and performance.

You will document designs, process specifications, qualification results, and technology roadmaps.

You will collaborate with quantum-device, circuit-design, cryogenic, materials, manufacturing, and systems teams.

You have a Bachelor’s or Master’s degree in electrical engineering, materials science, mechanical engineering, applied physics, or a related discipline.

You have experience in semiconductor packaging, wafer-level integration, MEMS, microfabrication, or heterogeneous integration.

You are familiar with one or more relevant processes: wafer bonding, hybrid bonding, TSVs, flip-chip assembly, thin-film deposition, lithography, etching, electroplating, or CMP.

You are familiar with package-level electrical, thermal, and mechanical design.

You have experience with CAD, electromagnetic simulation tools, multiphysics simulation, statistical analysis, or semiconductor process-development tools.

You have strong experimental, troubleshooting, documentation, and cross-functional communication skills.

Really nice to have:

PhD or equivalent industry experience in advanced packaging or semiconductor integration.

Experience with superconducting, semiconductor-spin, trapped-ion, neutral-atom, or photonic quantum-computing platforms.

Experience with RF/microwave interconnects, photonic coupling, or high-density chiplet systems.

Experience transferring a packaging or integration process from research into pilot or volume manufacturing.

60,000 euros - 78,000 euros yearly base salary

Stock options for every employee (BSPCE/ESOP)

Sponsored trip to conferences around the world

A highly dynamic international team

Swile meal vouchers

Mental health support with moka.care

Training budget/ Annual Learning & Development Allowance

Sabbatical leave (after 2 years in the company)

Vibrant office culture (two office spaces in the heart of Paris, team lunches, offsite events, Friday breakfasts..)

You want to have a key role in a growing startup with challenges at the frontier of the technology.

You want to contribute to achieving landmark results in quantum computing, making a difference in the emerging quantum technologies.

You want to work within a 60-people team with various backgrounds in nanofabrication, quantum electronics, and carbon nanotube science to create a revolutionary quantum computing processor.

You want to thrive in an exceptional scientific environment with several industrial and academic partners.

You share our values (excellence, scientific integrity, diversity, curiosity, and care) and want to help us define our product-focused culture and ambition to accelerate.

We still encourage even if you don’t meet all the requirements. Rest assured, we are committed to finding the right fit for our team and are open to adjusting compensations based on skills and experiences. Applications from women are especially welcomed!

3D Integration Engineer

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