A Belgian discovered a way to increase the speed of EUV scanners under simple conditions

New way to speed up image transfer when making microchips

When manufacturing chips the most important step is transferring the pattern from a mask onto the photoresist layer of a silicon wafer. This process requires a balance between quality and deposition speed, and traditional acceleration methods – increasing exposure power or raising photoresist sensitivity – come with problems.

The Belgian laboratory Imec proposed an unexpected solution that has not yet been considered in industry.

How the standard process works
1. Exposure

The wafer is scanned by an EUV source.

2. Baking and post‑exposure processing

After exposure, the wafer is placed in a box where baking and subsequent processing are performed under normal conditions: cleanroom, atmospheric pressure, oxygen content ~21 % (sea level).

New experimental scheme
Imec created a sealed box equipped with sensors to monitor gas composition and material parameters. This allowed baking and post‑exposure processing with various gas mixtures, as well as collecting data on the photoresist at each stage.

Key discovery
- Raising the oxygen concentration to 50 % during processing increases the photoresist sensitivity by about 15–20 %.

- This means that the desired feature sizes can be achieved with a lower EUV dose – either transferring the pattern faster or with lower energy consumption without sacrificing line quality.

Why it works
Increasing oxygen stimulates chemical reactions in exposed areas of metal‑oxide photoresists (MOR). These materials are already considered promising for EUV projection at low and especially high numerical aperture. Therefore, simply changing the gas environment can boost the performance of modern EUV scanners.

Practical significance
- Increased efficiency without modifying the scanners themselves.

- Need to implement new wafer processing conditions and associated costs.

- Potential interest from manufacturers, although it is still unknown how quickly they will adopt this “life‑hack”.

Thus, Imec has shown that changing the gas environment during baking can become an effective tool for accelerating the production of advanced microchips.