Imaging and Inspection

 

The research topic Imaging and Inspection addresses the following research tasks:

  1. High-resolution bright and dark-field microscopy (Contact person Sascha Brose)
  2. Optimization of in-vacuum EUV detection (Contact person Lukas Bahrenberg)
 
 

High-resolution bright and dark-field microscopy

EUV zoneplate (left), ABIT inspection tool (right) Copyright: © Fraunhofer ILT EUV zoneplate (left), ABIT inspection tool (right).

The group has a significant experience in the design, construction and application of EUV microscopes using reflective and diffractive optical elements. Depending on the application, reflection as well as transmission microscopes can be realized. The main applications of such microscopes are the investigation of nanostructures and the detection of nanodefects in thin films or on reflective surfaces. Thanks to the small wavelength of EUV radiation, such microscopes provide an excellent resolution and sensitivity on the nanoscale.

One example of the potential of such systems is the dark-field inspection microscope realized by the group together with an industrial partner. The prototype tool of an EUV actinic mask blank inspection tool (ABIT) demonstrates moderate spatial resolution and a large field of view. This tool can detect the presence of defects with sub‑50 nanometer sizes and is used for the investigation of the limits of defect inspection in dependence of industrially-relevant parameters, such as throughput and sensitivity.

 
 

Optimized solutions for EUV detection

EUV scintillator (left), EUV in-vacuum CCD detector (right) Copyright: © Fraunhofer ILT EUV scintillator integrated in a vacuum flange (left), customized EUV in-vacuum CCD detector (right).

Various imaging and metrology applications of EUV radiation require customized solutions for EUV detection. The group has realized both compact in-vacuum detectors based on EUV-sensitive CCD sensors as well as scintillator-based detection systems with down to 1 micrometer spatial resolution. For high throughput applications, time delay integration (TDI) CCDs or high-speed CMOS detectors are employed.