METHOD FOR DEEP ANISOTROPIC PLASMA ETCHING OF SILICON STRUCTURES Russian patent published in 2024 - IPC H01L21/3065 

FIELD: various technological processes; electricity.

SUBSTANCE: invention relates to production of microelectromechanical systems based on silicon. Method of deep anisotropic plasma etching of silicon is a cyclic three-step process. At the first stage of the cycle, isotropic etching of silicon in a gas mixture of SF₆ gas and oxygen takes place. Second stage is characterized by polymerisation of the surface of the structure in an octafluorocyclobutane medium to prevent lateral etching. At the third stage, the polymer layer at the bottom of the structure is removed by directed sputtering with argon ions, after which the cycle is repeated. During continuous etching of deep structures with a large opening area, excessive heat release occurs, which results in overheating of the treated silicon wafer. In order to prevent occurrence of negative effects as a result of overheating of the treated structure, an interval treatment method is used, in which after a certain number of cycles the wafer is removed from the reactor and cooled down.

EFFECT: considerable improvement of such parameters as anisotropy, uniformity and quality of etching of silicon structures.

1 cl, 2 dwg