ナノメディシンとナノテクノロジーのジャーナル

概要

Recent Development of Si Chemical Dry Etching Technologies

Toshio Hayashi

Chemical dry etching in wafer processing was innovated and developed in 1976 using CF4/O2 downflow plasma for poly-Si etching. Thereafter, many researchers developed and reported various chemical dry etching methods.

Advanced Si chemical dry etching technology was developed in 2010, using N2 downflow plasma and NF3 flowing to the downflow plasma area. The etchant production mechanism for this technology was explained by us. In these technologies, the plasma source is necessary to produce the etchants (F for Si etching and HF+NH3 for SiO2 etching).

Recently, a novel Si chemical dry etching technology was innovated and developed by us without plasma source, in which F atoms generated in F2+NOF+FNO reaction are used for Si etching in the pressure range of 100 to 1000 Pa. The etch rate at room temperature is more than 5000 nm/min, and is dependent on the flow rate and on the distance between the gas mixing point and the wafer position. Increasing the substrate temperature, the minimum etch rate was obtained at 60ºC. Over this temperature, the etch rate increased again with increase of the substrate temperature. In the lower temperature region, the chemisorbed layer may be formed and the chemical reaction may be enhanced in this condensed layer. Increasing the temperature, this chemisorbed layer disappears around 60ºC. Over this temperature, the surface reaction mainly takes place according to Arrhenius equation.