Senior Process Engineer

Plessey has a long history of innovation. Founded in 1956, we have evolved from one of Europe’s earliest semiconductor pioneers into the world’s most advanced Micro

LED specialist. Over the decades, Plessey has built a first class, fully integrated platform designing, manufacturing, and engineering next-generation display technologies entirely in-house. This end to end capability, combined with our strong IP portfolio, uniquely positions us to lead the scaling of Micro

LEDs from lab innovation to high-volume production.

Our future is even brighter. We believe Micro

LEDs will define the next era of technology—powering ultra-efficient AR/VR displays, driving optical processors that make AI faster and more sustainable, and enabling devices yet to be imagined. With our unique expertise and talented team, we are positioned to lead this transformation.

It’s an exciting time to join us:
Plessey has recently been acquired by Haylo Labs, accelerating our growth and opening new opportunities.

• Commitment
• Care

Located at our head office and state-of-the‑art fabrication facility in Plymouth.

The Thin Film Ellipsometry Process Engineer is responsible for developing, optimising, and controlling thin‑film optical measurement and characterisation processes to support high‑yield, high‑performance semiconductor device fabrication. This role focuses on ellipsometry‑based metrology for deposited thin films across development and production environments.

• Develop, qualify, and optimise ellipsometry measurement processes for thin films (thickness, refractive index n/k, composition, and uniformity).
• Support R&D and new materials development by providing accurate thin‑film characterisation, measurement development, and data analysis.
• Own and maintain ellipsometry process recipes, optical models, and control strategies.
• Provide accurate metrology feedback to thin‑film deposition processes (e.g., PVD, CVD, ALD).
• Analyse film properties including thickness mapping, optical constants, and process‑induced variation.
• Develop and refine optical models for multilayer thin‑film stacks.
• Utilise statistical process control (SPC) to monitor tool performance and process stability.
• Conduct root cause analysis for measurement drift, model instability, or yield excursions related to film properties.
• Collaborate with equipment and process engineering teams to maintain and improve metrology tool performance.
• Support new product introduction (NPI) through film characterisation, DOE planning, and process transfer.
• Generate technical reports and present findings to engineering and management teams.
• Ensure compliance with safety and cleanroom protocols.

• Bachelor’s or Master’s degree in Materials Science, Physics, Electrical Engineering, or related field.
• 3–7+ years of experience in semiconductor or advanced thin‑film processing environments.
• Strong hands‑on experience with spectroscopic ellipsometry.
• Solid understanding of thin‑film optics, dispersion modelling, and multilayer analysis.
• Experience correlating ellipsometry data with complementary techniques (e.g., XRD, AFM, profilometry).
• Strong data analysis and problem‑solving skills.
• Strong ownership mentality with the ability to work independently in a fast‑paced environment.
• Adaptable and comfortable with evolving priorities and rapid change.
• Excellent cross‑functional collaboration skills (working effectively with process, equipment, R&D, and manufacturing teams).
• Clear and confident communicator, able to present technical findings to both technical and non‑technical audiences.
• Experience with compound semiconductor or dielectric thin films would be an advantage.