Damage-free metal-oxide-semiconductor gate electrode patterning on thin HfSiON film using neutral beam etching

Abstract

The charging damage of metal-oxide-semiconductor (MOS) capacitors and the degradation of HfSiON dielectric films during gate electrode etching were compared with neutral beam etching and conventional plasma etching. Furthermore, residual flux of charged particles (positive/negative ions and electrons) in the neutral beam was analyzed and the relationship between the residual charge flux and the charging damage induced in SiO2 and/or HfSiON gate dielectrics was investigated. Although the residual charge flux and its composition varied depending on the neutral beam acceleration method (dc or rf biasing), the amounts were noticeably lower than that with the plasma etching system. The gate leakage currents of the MOS capacitors etched using the neutral beam were sufficiently lower than those in the plasma etching, which was consistent with the charge flux during the gate electrode etching. On the neutral beam irradiated surface of the HfSiON film, there were no changes in the x-ray photoelectron spectrometry spectra, while large decreases in Hf composition were observed on the plasma-irradiated surface.

Emerging Plasma Nanotechnology

“…Thanks to neutralization, when the ion current density in plasma was about several mA/cm 2 , the residual charge could be reduced to several μA/cm 2 by inserting a carbon aperture. The angular spread of the neutral beam was estimated to be 90 ± 5° from the neutral beam energy distribution, 27,28) after which the application of silicon etching using a Cl2-based neutral beam resulted in no undercut. The etch rate uniformity was less than ±5% within the 200-mm diameter substrate and a perfectly uniform etching within a local area of 1 cm 2 on the Si substrate was achieved 27,28) .…”

“…The angular spread of the neutral beam was estimated to be 90 ± 5° from the neutral beam energy distribution, 27,28) after which the application of silicon etching using a Cl2-based neutral beam resulted in no undercut. The etch rate uniformity was less than ±5% within the 200-mm diameter substrate and a perfectly uniform etching within a local area of 1 cm 2 on the Si substrate was achieved 27,28) . The etch rate increased by applying bias power to the neutralization aperture plate, which shows that an accelerated neutral beam was successfully obtained.…”

“…The n was 1.90 for the 200-cycle HfO2 film, which is close to the reference value of amorphous HfO2 film. [27][28][29] Since it is a gate dielectric film, amorphous HfO 2 was able to achieve high insulation and a low leakage current. These findings demonstrate that the HfO2 film grown using our neutral beam oxidation technique provided a high-quality HfO 2 /SiO 2 stack film and interface even at room temperature.…”

Progress and prospects in nanoscale dry processes: How can we control atomic layer reactions?

“…The etching of metals also has the problem of the redeposition of etching by-products. 12,[188][189][190][191][192][193][194][195][196][197] In self-limiting formation, another difficulty arises for intermetallic compounds or alloys such as CoFe, NiFe, CrFe, and PtMn. Simply, in etching processes for compounds such as high-k materials, dichalcogenides, GaAs, GaP, and GaN, it is difficult to maintain the surface stoichiometry during and after the etching.…”