AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoP

Paper PS-MoP11
Si@sub x@O@sub y@F@sub y@ Passivation Layer in the Silicon Deep Etching Cryogenic Process

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: X.M. Mellhaoui, GREMI - Orléans University, France
Authors: X.M. Mellhaoui, GREMI - Orléans University, France
R.D. Dussart, GREMI - Orléans University, France
T.T. Tillocher, GREMI - Orléans University, France
P.L. Lefaucheux, GREMI - Orléans University, France
P.R. Ranson, GREMI - Orléans University, France
Correspondent: Click to Email
Silicon etching is perfomed by a cryogenic SF@sub 6@/O@sub 2@ plasma process. This process allows to obtain a high aspect ratio (depth/width > 10) and a high anisotropy. The plasma is created in an Inductively Coupled Plasma reactor (Alcatel 601E). The silicon wafer is clamped on a electrostatic chuck cooled with liquid nitrogen and controlled in temperature with thermal resistances. A study of passivation mechanisms is necessary to perfectly control this process and to optimize the trench profiles. The passivating layer is a mixture of Si, F, O (Si@sub x@O@sub y@F@sub z@). Previous XPS experiments have shown that the passivation layer is removed during the increase of temperature. When destroyed, this layer can be rebuilt with a plasma mixture of SiF@sub 4@ and O@sub 2@. This particular experiment was made and has revealed that the presence of sulphur is not necessary to build an efficient passivation layer. In new experimental ICP reactor was equipped with a spectroscopic ellipsometer. This new diagnostic allowed to characterize the kinetic of passivation layer growing in the cryoetching process, and it desorption when the wafer is warmed. Mass spectrometry experiments were also carried to analyze the desorbed species These new results will be presented at the conference.