UV-ozone cleaning system from FHR Anlagenbau GmbH. Heater temperture up to 250°C. Substrate up to 8". Process in atmospheric pressure. Location: room Q158, NANO-process lab.

As part of normal lamp aging, the UV intensity gradually decreases over time. This is a natural and expected behavior and can result in a gradual reduction in the process or etch rate. As the lamp continues to age, some processes may therefore require slightly longer exposure or process times to achieve the same result.
Importantly, there has been no abrupt change in the tool performance. If you have been using a recipe successfully in recent weeks or months, there is no need to make any immediate changes to your process.
For older recipes, or if you notice that your process result is slightly below the expected level, you may need to gradually increase the process time and perform some minor tuning. The exact adjustment can vary depending on the resist and process conditions.
The tool continues to operate consistently and can be used as usual. The updated baseline data for PMMA shows the same overall etching behavior as before, but with a gradual shift in the etch-rate versus process-time curve, consistent with the expected reduction in lamp intensity over time.