PROCEDURE FOR FABRICATING DEVICES INVOLVING DRY ETCHING

摘要

- 18 -PROCEDURE FOR FABRICATING DEVICESINVOLVING DRY ETCHINGAbstractThe present invention relates to a process forfabricating a device comprising the steps of forming a resistmask on a substrate, etching the substrate to form a pluralityof etch pits defining a plurality of features by inducingreaction of the substrate with energetic species andcompleting the device. The redeposition of material on theside walls of the etch pit ocours during the etching. Theprocess includes at least one step chosen from the group ofsteps consisting of, 1) locally compensating for the effect ofthe redeposition on the conformation of the sidewall,2) when the redeposition material presents a barrier toisotropic etching in the sukstrate, contacting the etchingspecies with the resist mask so that the angle formed betweena) a tangent to the resist mask at the point the resist maskintercepts the substrate and (b) a perpendicular to thesubstrate at the point is less than arctan (X/Y), where X isthe horizontal rate of the redeposition at the point and Y isthe etchant rate of the substrate, and (3) limiting, when theredeposited material presents a barrier to isotropic etchingin the subatrate, the contact angle between the momentumdirection of the etchant species and a tangent to theredeposition material at all points on the resistantredeposition material serving to mask the sidewalls so thatthe contact angle is less than arctan (X/Z), where X is asdefined in step 2), where Z is the etchant rate of theredeposited material in a direction parallel to the etchantspecies momentum direction.