Thermostable Mo-based electron lithography marks

A method of mark deposition for electron beam lithography was developed. It solved the problem of a dry photoresist explosion. This occurs during the deposition of refractory metals thick layers. The photoresist degradation leads to bad morphology, poor adhesion and non-linear edges of the metal. We used an additional sublayer of aluminum and carried out the molybdenium deposition process with interruptions. The final marks layer composition is 10 nm of aluminium and 150 nm of molybdenum. The optimal pause between the processes is 10 minutes, deposition step of molybdenium is 15 nm. Metallization showed good adhesion and smooth surface morphology. Electron beam lithography can recognize these marks. Annealing at the temperature of 870 degrees did not produce any significant changes. The marks have a high temperature and mechanical stability. This makes it suitable for gallium nitride based technology.