Oral title: Observing the first steps of planet formation with ALMA

Oral abstract: I will present ALMA observations of HL Tau, IM Lupi and HH 30. For the first time, we are able to directly measure the 
scale height of mm dust grains and compare it to the distribution of the gas and small micrometric grains seen in CO lines and 
scattered light. All these objects show an extremely flat dust disk and significant dust migration. I will discuss the implications 
for planet formation.