Two Cryogenic Processes Involving SF6, O2, and SiF4 for Silicon Deep Etching

Thomas Tillocher (1) , Remi Dussart (1) , Lawrence J. Overzet (2) , Xavier Mellhaoui (1) , Philippe Lefaucheux (1) , Mohamed Boufnichel (3) , Pierre Ranson (1)

1 GREMI - Groupe de recherches sur l'énergétique des milieux ionisés
2 PAL - Plasma Application Laboratory
3 ST-CROLLES - STMicroelectronics [Crolles]

Two types of silicon cryoetching processes are proposed. The first one consists of alternating SF6 plasma isotropic etching steps and SiF4/O2 passivation steps at low temperature of the silicon substrate. This process only works at very low temperature and avoids reactor wall contamination. A second process alternating long anisotropic SF6/O2 plasma steps with short SiF4/O2 overpassivating steps is investigated. This second process gives an etch rate as high as the one obtained in standard cryoetching and allows blocking of the undercut evolution. These two processes offer many advantages in terms of cleanliness, robustness, and performance.

Mots clés: Etching; cryogenic; silicon

Domaines: Physique des plasmas [physics.plasm-ph]

Thomas Tillocher, Remi Dussart, Lawrence J. Overzet, Xavier Mellhaoui, Philippe Lefaucheux, et al.. Two Cryogenic Processes Involving SF6, O2, and SiF4 for Silicon Deep Etching. Journal of The Electrochemical Society, 2008, 155 (3), pp.D187. ⟨10.1149/1.2826280⟩. ⟨hal-00349343⟩