| 摘要 |
PURPOSE:To form an ultrafine groove with good reproducibility by allowing a burying material (polysilicon) on the side wall of a pattern by an etching-back technique to remain, and then etching the material and an Si substrate disposed under the material. CONSTITUTION:An Si3N4 film 22 and an SiO2 film 23 having an ultrafine window are superposed on an Si substrate 21, and coated with a polysilicon 24. A polysilicon 25 is retained on the wide wall of the window by RIE. Then, an SiO2 film 26 is superposed, etched back, an SiO2 film 27 is retained at the center of the window to expose the polysilicon 25. With the films 27, 23 as masks the polysilicon 25 and the film 22 directly under the polysilicon 25 are etched. Subsequently, the substrate 21 is subjected to an RIE to form a groove 28. Thereafter, the insulating films 22, 23, 27 are etched to form a gate oxide film 29 and a gate electrode 30. Then, an ultrafine capacitor is obtained. This structure may be used widely for an element separation. |
