Abstract
In electrostatic electron optics charging on the surfaces of insulators separating the electrodes can cause undesired beam fluctuation. In prior work, the authors showed that coating the insulators with a film deposited by atomic layer deposition (ALD) could lead to acceptably low charging effects in the reflection electron beam lithography system. However, the stability of the resistivity can also be affected by contaminants present in the vacuum environment of the electron beam tool. The mechanism of formation for carbon layers typically involves the cracking of hydrocarbon contaminants adsorbed on the film surface by photon, electrons, or heat. This work describes changes in resistivity of ALD films of zinc–zirconium oxide and tantalum–niobium oxide 40 nm thick under different operating conditions. In a vacuum system utilizing an oil rough pump and a turbo pump, <0.01 C/cm2 bombardment with 309 V electrons results in about 1 order of magnitude reduction in surface resistance. This effect was not observed in an ion-pumped system suggesting that carbon contamination is the culprit. XPS measurements confirmed this suspicion. Improved results on a new material under development are presented.
Published Version
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