Dry etching characteristics of TiN film using Ar/CHF3, Ar/Cl2, and Ar/BCl3 gas chemistries in an inductively coupled plasma

Abstract

Dry etching characteristics of TiN film have been studied in the case of using Ar/CHF3, Ar/Cl2, and Ar/BCl3 chemistries in an inductively coupled plasma. The TiN film was not etched at all without the addition of CHF3, BCl3, or Cl2 to the Ar gas flow. On the other hand, it was found that the TiN film was etched with one of the earlier additional gases. It was also found that a nontapered profile of etched TiN is obtained by Cl2 addition and a tapered profile by CHF3 or BCl3 addition. Moreover, a lower taper angle is obtained by increasing the amount of additional BCl3. X-ray photoelectron spectroscopy and Auger electron spectroscopy analyses for the etched samples of TiN show that TiF3 exists on the etched surface of TiN in the case of CHF3 addition and that BOxNy exists in the case of BCl3 addition. On the basis of these results, the effect of the gas addition to Ar on the characteristics of TiN reactive ion etching is considered as follows; under the Ar/CHF3 condition, although N in the TiN film is removed by evaporation in the form of NFx, Ti is fluorinated to form TiFx having low vapor pressure, which results in the low etching rate. Under the Ar/Cl2 condition, since NClx and TiClx have high vapor pressures, TiN is easily etched off, resulting in the highest etching rate with a nontapered profile. Under the Ar/BCl3 condition, although Cl plays the same role as it does under the Ar/Cl2 condition, B is likely to form a nonvolatile compound such as BOxNy, resulting in the deposition of the nonvolatile films on both the upper surface and sidewall of the TiN, which leads to a lower etching rate than that in the case of Cl2 addition and a lower taper angle of the etched profile.

Remote plasma etching of titanium nitride using NF3/argon and chlorine mixtures for chamber clean applications

“…This result is surprising when comparing to literature data [2,[5][6][7]. In situ wafer etch applications usually use chlorine or BCl 3 for the removal of TiN.…”

Chemical Reaction on Etched TaNO Thin Film as O2 Content Varies in CF4/Ar Gas Mixing Plasma

“…the RF power, DC-bias voltage, process pressure, and substrate temperature, were maintained at 700 W, -250 V, 2 Pa, and 40℃, respectively. As the O 2 content in the CF 4 /Ar gas plasma increased, the etch rates and selectivity of the TaNO thin films increasesd The maximum etch rate of TaNO thin film was 297.1 nm/min at O 2 /CF 4 /Ar (=6:16:4 sccm) [10,11]. This implies that, for a given range of experimental conditions, the chemical reactions were more effective than the physical etch pathway.…”

Inductively coupled plasma reactive ion etching of titanium nitride thin films in a Cl2/Ar plasma

“…The increase in the etch rate with increasing Cl 2 chemical gas means that the etching obeys the reactive ion etching mechanism [6]. As the Cl 2 concentration increased, the etch rate was enhanced due to the increase of chemical reaction between TiN and chlorine radicals [8]. The etch rate of photoresist mask almost linearly increased with increasing Cl 2 concentration.…”