Speaker
Description
The CERN MPT workshop operates a magnetron sputtering machine to develop thin-film resistive and metallic coatings for Micro-Pattern Gaseous Detectors (MPGDs). The three main base materials are: DLC, DLC+ (DLC/Ti/Cu), and double-sided DLC++. Process optimisation has recently replaced Cr with Ti as an adhesion layer, improving etching control and reproducibility. At the end of 2025, the first DLC++ foils with matched resistivity on both sides were successfully produced, enabling full in-house fabrication of MPGD base materials.
The talk will focus on different facets of the production processes for base materials and the development of new manufacturing processes for resistive and chemically resistant layers.
A key focus is the uniformity of resistivity across large-area foils. Systematic studies show that gas distribution strongly influences plasma density and film properties. Optimised gas outlet configurations significantly improved uniformity, enabling full-area usage and increased yield. This is essential for the production of large-area detectors.
Reproducibility is ensured by calibrating the C₂H₂ amount at the start of each deposition series. Small variations allow controlled tuning of surface resistivity from a few MΩ/□ to several tens of MΩ/□.
These developments support MPGD R&D towards improved detector stability and rate capability. While higher resistivity enhances stability, it limits rate performance in single-layer designs, motivating multilayer concepts such as double-DLC structures with vertical charge evacuation.
In parallel, new materials (e.g. B₄C) and processes, including deposition on PMMA and PCB substrates and lift-off patterning of multilayer films, are being developed, extending the flexibility of MPGD base material production. In this context, lift-off processes are currently being developed to pattern DLC, enabling the fabrication of fully DLC-based MPGDs, such as double-sided DLC-GEMs.
| Name of the speaker | Karl Jonathan Flöthner |
|---|---|
| Eligible for the Georges Charpak Young Scientist Award. | yes |