X-ray photoelectron spectroscopy investigation of sidewall passivation films formed during gate etch processes

Abstract

Articles you may be interested in X-ray photoelectron spectroscopy analysis of the effect of temperature upon surface composition of InP etched in Cl2-based inductively coupled plasma

Sidewall passivation assisted by a silicon coverplate during Cl2–H2 and HBr inductively coupled plasma etching of InP for photonic devices

“…In-depth investigation has been carried out in the past decade to explain the anisotropy of this process, and it was demonstrated that the etching of sub-100-nm Si gate was possible due to the deposition of a SiOCl or SiOBr passivation layer on the gate sidewall. 14,15 Moreover, it was reported that the use of HBr in the gas mixture significantly improves the process, 16 the exact physicochemical origin of this effect being not yet well explained to our knowledge.…”

“…It was indeed reported from x-ray photoelectron spectroscopy ͑XPS͒ analysis of the sidewalls of poly-Si patterns etched with Cl 2 -HBr-O 2 gas mixtures that Cl or Br desorption and substitution by oxygen take place under air exposure. 16 However, it should be considered that oxygen in the plasma can also come from the sputtering of the inner parts of the reactor, especially in our very low pressure conditions since decreasing the pressure leads to an increase of the plasma potential as observed from separate Langmuir probe measurements. 17 Moreover, as seen from the results obtained when O 2 is added in situ to the gas mixture, only a very small proportion of oxygen is sufficient to increase the O atomic concentration in the redeposition layer.…”

“…In the detailed XPS analysis carried out in Ref. 16, it was suggested that the SiOCl or SiOBr passivation layer deposited on the Si sidewalls is densified and transformed in a more SiO 2 -like layer in the presence of oxygen. The possible densification of the layer in the presence of oxygen could also take place in our case and could explain the better anisotropy and the extremely low sidewall roughness obtained with the Cl 2 -H 2 -O 2 and the HBr-O 2 processes.…”

Effect of halogen in high‐density oxygen plasmas on photoresist trimming

“…The plasma chemistry used for polysilicon etching in this study is HBr/Cl 2 . As mentioned earlier, when etching with HBr/O 2 or Cl 2 /HBr/O 2 plasmas, or with addition of a small amount of oxygen to the Cl 2 plasma, the bottom of the polysilicon trenches became bumpy and the etch rates were nonuniform (Denton and Wallace, 1992;Desvoivres et al, 2001;Guinn et al, 1995;Lehmann and Widmer, 1980). Their XPS analyses reveal that the deposit is mainly either SiO x Cl y or SiO x Br y .…”

“…Moreover, the difficulty of the etched products to be diffused out from the line arrays may be attributable to the microloading effects as well (Plummer et al, 2000). Interestingly, Desvoivres et al (2001) found the tapered thickness of the SiO 2 passivation layers on the sidewall of the Si-gate features when etched in HBr/O 2 high-density plasmas. That is, the passivity is not uniform through the sidewall of the features.…”