Two-step dry etching method for low surface damage in semiconductor device preparation

The invention discloses a two-step dry etching method for low surface damage in semiconductor device preparation. The two-step dry etching method comprises the steps of (1) cleaning the surface of a device; (2) carrying out high-speed longitudinal ICP dry etching; and (3) carrying out low-speed longitudinal ICP dry etching. The method is characterized in that the RF power in the step (2) is more than 200% of the RF power in the step (3), and the ICP power in the step (3) is more than 200% of the ICP power in the step (2). According to the invention, two sets of different etching powers are adopted successively to achieve two-step etching, the mechanism is mainly that when ICP etching is close to the designed depth of the device, the main etching mechanism is changed from an ion bombardmenteffect to surface ion chemical reaction, the final etching structure is completed by means of the surface chemical reaction with small kinetic energy, and thus the surface etching damage is reduced to the minimum range. 本发明公