28 research outputs found
Plasma-assisted Atomic Layer Deposition:High-volume manufacturing and new opportunities in research
The usage of plasma as a reactant in atomic layer deposition processes started out as a niche process but in the meantime had its breakthrough in high-volume manufacturing in nano-electronics.Understanding the processes in plasma ALD is challenging but the knowledge in the Netherlands on plasma science, surface science and the ALD end-applications are a perfect foundation for a globally leading position in this field
Evidence for low-energy ions influencing plasma-assisted atomic layer deposition of SiO2 as measured with Impedans' Quantum System:Application note [QC03]
Evidence for low-energy ions influencing plasma-assisted atomic layer deposition of SiO2 as measured with Impedans' Quantum System:Application note [QC03]
Isotropic atomic layer etching of GaN using SF<sub>6</sub> plasma and Al(CH<sub>3</sub>)<sub>3</sub>
GaN is an enabling material for light emitting diodes, advanced radio frequency, and power semiconductor devices. However, fabrication of GaN devices often relies on harsh etch processes, which can leave an etch damage layer, limiting final device performance. In this work, an isotropic atomic layer etching (ALE) process involving SF6 plasma and trimethylaluminium [Al(CH3)3] is presented for the controlled etching of GaN, which reduces oxygen and carbon contamination while smoothing the surface. The ALE chemistry was first examined with density functional theory. A comparison between proposed thermal and plasma-driven reactions is made by implementing Natarajan-Elliott analysis, highlighting that the plasma process is a good candidate for GaN ALE. Saturation was experimentally confirmed for both ALE half-cycles at 150 and 300 °C, with etch rates of 0.31 ± 0.01 and 0.40 ± 0.02 nm/cycle, respectively. Analysis of the films post-ALE shows that the RMS roughness of the films decreases from 2.6 ± 0.1 to 1.9 ± 0.1 nm after 25 nm of etching at 300 °C, in agreement with a previously developed curvature-dependent smoothing model. Taken together, this ALE process enables accurate GaN thickness tuning, surface cleaning, and surface smoothing, allowing for further development of GaN devices.</p
Atomic insights into the oxygen incorporation in atomic layer deposited conductive nitrides and its mitigation by energetic ions
Oxygen is often detected as impurity in metal and metal nitride films prepared by atomic layer deposition (ALD) and its presence has profound and adverse effects on the material properties. In this work, we present the case study of HfNx films prepared by plasma-assisted ALD by alternating exposures of CpHf(NMe2)3 and H2 plasma. First, we identify the primary source of O contamination in the film. Specifically, we find that the extent of O incorporation in HfNx films is determined by the flux of background H2O/O2 residual gases reaching the HfNx surface during the ALD process and leads to the formation of Hf–O bonds. Then, we report on the decrease in the concentration of Hf–O bonds in the film upon application of an external radiofrequency (rf) substrate bias during the H2 plasma step. The experimental work is accompanied by first principles calculations to gain insights into the O incorporation and its mitigation upon the impingement of energetic ions on the surface. Specifically, we find that the dissociative binding of H2O on a bare HfN surface is highly favored, resulting in surface Hf–OH groups and concomitant increase in the oxidation state of Hf. We also show that energetic cations (H+, H2+ and H3+) lead to the dissociation of surface Hf–OH bonds, H2O formation, and its subsequent desorption from the surface. The latter is followed by reduction of the Hf oxidation state, presumably by H˙ radicals. The atomic-level understanding obtained in this work on O incorporation and its abstraction are expected to be crucial to prevent O impurities in the HfNx films and contribute to the fabrication of other technologically relevant low resistivity ALD-grown transition metal nitride films
Plasma atomic layer deposition
Plasma atomic layer deposition (ALD) is optimized through modulation of the gas residence time during an excited species phase, wherein activated reactant is supplied such as from a plasma. Reduced residence time increases the quality of the deposited layer, such as reducing wet etch rates, increasing index of refraction and/or reducing impurities in the layer. For example, dielectric layers, particularly silicon nitride films, formed from such optimized plasma ALD processes have low levels of impurities remaining from the silicon precursor.</p
Plasma atomic layer deposition
Plasma atomic layer deposition (ALD) is optimized through modulation of the gas residence time during an excited species phase, wherein activated reactant is supplied such as from a plasma. Reduced residence time increases the quality of the deposited layer, such as reducing wet etch rates, increasing index of refraction and/or reducing impurities in the layer. For example, dielectric layers, particularly silicon nitride films, formed from such optimized plasma ALD processes have low levels of impurities remaining from the silicon precursor.</p
Plasma atomic layer deposition
Plasma atomic layer deposition (ALD) is optimized through modulation of the gas residence time during an excited species phase, wherein activated reactant is supplied such as from a plasma. Reduced residence time increases the quality of the deposited layer, such as reducing wet etch rates, increasing index of refraction and/or reducing impurities in the layer. For example, dielectric layers, particularly silicon nitride films, formed from such optimized plasma ALD processes have low levels of impurities remaining from the silicon precursor.</p
Plasma atomic layer deposition
Plasma atomic layer deposition (ALD) is optimized through modulation of the gas residence time during an excited species phase, wherein activated reactant is supplied such as from a plasma. Reduced residence time increases the quality of the deposited layer, such as reducing wet etch rates, increasing index of refraction and/or reducing impurities in the layer. For example, dielectric layers, particularly silicon nitride films, formed from such optimized plasma ALD processes have low levels of impurities remaining from the silicon precursor.</p