According to a review of the literature (see table 1.1) dating from 1991, the /s/ and /z/ phonemes are realised with:

a tip-down laminal tongue position.

The reports are evenly split between dental and alveolar for the place of articulation of /s/ and /z/, whereas /l/ is very much apical, and /t/, /d/, /n/ are reported as apical [and dental] by the majority of sources.

The study also reported that for laminal /s/ and /z/

tend to be articulated farther back in English than in French