Impact of chemistry on profile control of resist masked silicon gates etched in high density halogen-based plasmas

Abstract

Testing new chemistries for mask repair with focused ion beam gas assisted etchingCritical dimension ͑CD͒ control during silicon gate etching has been investigated with state-of-the-art chemistries. In particular, we have compared the etched profile of both isolated and dense gates obtained after the main etch step of a gate etch process using HBr/Cl 2 /O 2 and HBr/Cl 2 /O 2 /CF 4 gas mixtures, and study the influence of the CF 4 /O 2 ratio in this mixture. We demonstrate that the gate etch profile is mainly driven by the passivation layer deposited on the gate and mask sidewalls during the etching. Due to aspect ratio dependant etching effect the passivation layer formation is thinner in dense than in isolated structures resulting in significant profile microloading. However, CF 4 addition to HBr/Cl 2 /O 2 strongly minimizes the difference in passivation layer thickness between dense and isolated lines thus potentially improving the critical dimension control. These results will be discussed in terms of chemical composition of the passivation layer and deposition mechanisms, based on previous studies by x-ray photoelectron spectroscopy and mass spectrometry studies. Finally, we will discuss the influence of the soft-landing and overetch steps on the final profile of the gates, and show that aspect ratio dependant etch rate during the main etch step of the process can become an additional source of CD microloading.

Thermal stability of superhydrophobic, nanostructured surfaces

“…glow discharge of CF 4 gas at 30 mTorr and À600 V of bias voltage [15]. This simple etching procedure produced nanopillars on the Si surface without forming a mask caused by the local deposition of carbon films from the CF 4 gas (a self-masking effect) and the preferred etching of Si with the F atoms [16,17], which have high reactivity toward Si [18]. CF 4 plasma treatment duration ranging from 5 to 60 min was chosen to give the desired roughness or solid fraction of the surfaces [15].…”

Fabrication of Photonic Wire and Crystal Circuits in Silicon-on-Insulator Using 193-nm Optical Lithography

“…Therefore ME1 is tailored to decrease the lateral CD bias between isolated structures (wires) and dense structures (photonics crystals) [20]. After ME1, we switch to ME2, which uses HBr/O2 chemistry to etch the major part of Si.…”

Nanoimprinting lithography on 200mm wafers for optical applications

“…To by-pass this residual layer thickness non-uniformity, two processes were performed onto printed wafers: the first process lasted t 0 (named HO process); the second one lasted t 0 + 10 s (named HO+ process). The transfer of resist patterns into silicon substrates (optical encoder) was done with as a well-known Cl 2 /HBr/O 2 chemistry, already used for industrial processes [8]. For OLEDs, resist patterns were transferred into a SiO 2 layer with a CH 2 F 2 /CF 4 /Ar chemistry.…”