Application of ultra-thin aluminum oxide etch mask made by atomic layer deposition technique
Journal of Physics, Conference Series
Grigoras, K.; Sainiemi, L.; Tiilikainen, J.; Säynätjoki, Antti; Airaksinen, V-M.; Franssila, Sami Application of ultra-thin aluminum oxide etch mask made by atomic layer deposition technique Abstract. Ultra-thin layers of aluminum oxide (less than 1 nm) were grown by atomic layer deposition (ALD) technique on hydrogen-terminated silicon substrates. A new technique, called "plasma defect etching", was proposed for the continuity evaluation of such a layer. The layer was examined by using it as a
... ed by using it as a mask in silicon etching at cryogenic temperatures in a DRIE reactor. The etch profile was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Island formation during initial cycles was confirmed. Thicker aluminum oxide layers (1-5 nm thick) were patterned by wet or dry (plasma) etching and used as a mask for deep silicon etching at cryogenic temperatures in a DRIE reactor, using SF 6 and O 2 gas mixture. We found aluminum oxide to be an extremely resistant mask, etched only 0.05 nm/min. The value for the Si to Al 2 O 3 selectivity reached 70 000:1.