Abstract: The present invention concerns a process for the control in real time of the etching in a process for manufacturing electronic components of the type obtained by reacting ionic etching of wafers of silicon utilizing a plasma produced between two electrodes, wherein the gaseous species of the plasma are analyzed during the etching, at least one of the wafers of silicon being removable in situ from the influence of the plasma.The invention also concerns a reactor therefore, comprising a housing under vacuum 31 including at least one support electrode 34 and one electrode 35 connected to ground between which a plasma is produced, means for producing a vacuum, means for loading and unloading wafers, means for introducing etching gas, wherein the reactor comprises at least two locations 40 for wafers 33, means for withdrawing at least one location from the influence of the plasma 37, said means and the locations being movable with respect to one another, and means for analyzing gaseous species of the plasma.