Interface Between Atomic Layer Deposition Ta₂O₅ Films and GaAs(100) Surfaces

Abstract

Ta 2 O 5 films were deposited on GaAs(100) surfaces using thermal atomic layer deposition from pentakis dimethyl amino tantalum (PDMAT) and H 2 O. The interface between the films and native oxide covered GaAs surfaces has been examined using X-ray photoelectron spectroscopy as a function of film thickness and for deposition temperatures ranging from 200 to 350°C. Gradual removal of the surface arsenic and gallium oxides was observed, with the removal of the arsenic oxides in general more efficient. The high oxidation states of both the arsenic and the gallium oxides were also found easier to remove. Elevation of the process temperature above 300°C resulted in significant enhancement of the native oxide removal rate. When films were deposited on GaAs surfaces that had the surface oxides removed, a practically sharp interface between the film and the GaAs substrate was maintained.

Comparison of the reactivity of alkyl and alkyl amine precursors with native oxide GaAs(100) and InAs(100) surfaces

“…A large body of work on the TMA/III-V system has shown this interaction to be a first-contact effect that ceases shortly after the III-V surface has been covered with a monolayer of Al 2 O 3 [19,20,30]. However in the case of amide precursors continuous removal of the surface native oxides has been documented even after the surface has been covered by several monolayers of the growing film [4,9,[22][23][24]. This is confirmed to a certain extent in this work as shown in Figures 2 and 3.…”

“…For example, it was proven that native oxide removal through reactions with TMA was a first-contact effect [5,[16][17][18][19][20][21]. But for ALD processes that used alkylamine precursors the well-documented continuous removal of the III-V surface native oxides even after the surface had been covered with 2 nm or more of the growing film hinted at the existence of a more complex reaction mechanism [4,9,[22][23][24].…”

Decomposition of Metal Alkylamides, Alkyls, and Halides at Reducible Oxide Surfaces: Mechanism of ‘Clean-up’ During Atomic Layer Deposition of Dielectrics onto III–V Substrates

“…Indeed, this ligand transfer mechanism has been proposed by others 3a, 8 to explain the clean-293 up effect. Experimental study clearly shows enhancement of the clean-up process with increasing 294 temperature when metal alkylamides are used 5,23 . Even though the first step of the ligand exchange 295 reaction is extremely facile, both thermodynamically and kinetically, significant kinetic requirements 296 may originate from steric effects in subsequent steps.…”

“…Such understanding can help achieve control of oxide-semiconductor 31 interfaces through the appropriate choice of chemical precursor. 32 alkylamides, and this differentiates these processes from TMA-based clean-up 5,11 . Granados-Alpizar 70…”

Doping Mechanism in Transparent, Conducting Tantalum Doped ZnO Films Deposited Using Atomic Layer Deposition

“…We note that the PDMAT may etch the ZnO surface as NH(CH 3 ) 2 is known to etch oxides . This may result in rougher surfaces for higher Ta doped ZnO films which could also explain higher ethane production immediately after PDMAT pulse.…”