Principal Process Engineer in Plymouth

Overview

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 MicroLED 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 MicroLEDs from lab innovation to high-volume production.

Our future is even brighter. We believe MicroLEDs 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.

Our Values

• Commitment
• Care

Location

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

About the role

We are seeking a Principal Process Engineer to lead the photolithography development of our next generation MicroLED technologies. Joining a talented team, this role owns & drives lithography processes, equipment, and metrology, helping us achieve target CDs, low overlay error and high yield in a fast-paced environment.

Responsibilities

• Develop and optimise Photolithography process for cutting-edge micro-LED device fabrications.
• Design and execute DOEs to understand process behaviour and expand process windows.
• Serve as a lithography tool owner, maintain peak performance, troubleshoot issues and coordinate with equipment engineering.
• Lead recipe optimisation and tool matching to ensure consistent, high quality outcomes.
• Utilise lithography metrology tools to monitor performance and implement continuous improvement.
• Analyse overlay budgets, critical dimensions (CD) trends and defect data to drive process enhancements.
• Establish statistical process control (SPC) systems and create clear, actionable process control dashboards.
• Investigate and perform root cause analysis for lithography-related challenges, including CD drift, resist adhesion, profile defects, and overlay errors.
• Drive yield and repeatability improvements across all lithography modules.
• Collaborate with etch, deposition, CMP, and development teams to ensure seamless integration of lithography steps.
• Provide guidance on mask design, design rules, and alignment mark strategies.
• Prepare comprehensive training manuals, ARIs, TFPs, and technical reports for internal teams.
• Present process improvement plans and roadmap proposals to engineering teams and management.
• Mentor and guide junior engineers and technicians in training, troubleshooting, and technical development.
• Lead problem-solving sessions and support data-driven decision-making across projects.

Experience & Attributes

• Degree in Engineering, Materials Science, Physics, or a related field.
• Over 5 years of hands-on experience with photolithography in semiconductor manufacturing, R&D, or pilot fabs.
• Skilled in using photolithography steppers, mask aligners, track systems, overlay measurement tools, and CD-SEM equipment.
• Strong understanding of photoresist processing, CD control, overlay alignment, and troubleshooting lithography issues.
• Experienced in optimising processes, adjusting exposure and focus, managing alignment, and controlling feature profiles.
• Comfortable designing experiments and analysing results to improve processes.
• Able to diagnose and solve both equipment and process problems using data.
• Clear communicator with strong documentation habits and a collaborative mindset.
• Able to mentor junior engineers and lead technical discussions.
• Proactive, detail-oriented, and adaptable in fast-moving R&D environments.
• Familiar with tools and methodologies used for statistical analysis and process control such as SPC, JMP, or equivalent would be an advantage.