METHOD AND DEVICE FOR ANISOTROPIC ETCHING OF HIGH ASPECT RATIO

摘要

According to the invention, a substrate ( 2 ) contained in an enclosure ( 1 ) containing an atmosphere ( 5 ) that is maintained at low pressure by a device ( 6, 7 ) for generating a vacuum is subjected to plasma etching. Plasma generation means ( 8 ) generate a plasma ( 9 ) which acts on the surface ( 2 a) of the substrate ( 2 ). The etching method subjects the substrate ( 2 ) to an alternating succession of steps comprising: an attack step using a plasma of etching gas coming from an etching gas source ( 19 ), a second step of passivation by means of a plasma of passivation gas coming from a passivation gas source ( 20 ), and a pulse step of selective depassivation by the action of a plasma of a cleaning gas coming from a cleaning gas source ( 21 ) and serving to remove the polymer from the bottom zones of cavities ( 2 b) more effectively than does the etching gas. This makes it possible to make cavities ( 2 b) having an aspect ratio greater than 30, and to do so at higher speed, with good selectivity relative to the mask protecting the substrate ( 2 ).