| 摘要 |
PURPOSE:To obtain a layer free of reverse taper or shoulders, by selectively diffusing P in the non-etched section of a polysilicon layer, covering it with photoresist and subjecting RIE only to the layer not added with P. CONSTITUTION:SiO2 12, polysilicon 5 and Si3N4 15 are deposited on an N type Si substrate 12 in that order. A resist mask 14 is applied thereto and the film 15 is opened with CF4+H2 gas by RIE. The resist 14 is removed, and P is thermally diffused in the polysilicon 5. An SiO2 film 16 generated during this operation is removed and furthr the Si3N4 15 is also removed. A photoresist mask 16 having a predetermined pattern is then applied thereto such that the width d1 thereof is larger than the width d2 of a P-added layer 13. The polysilicon 5 is removed by RIE with Cl2F2 + N2 gas and the resist 24 is also removed. According to this method, no shoulder is produced at the interface between the SiO2 film 12 and the polysilicon 5, and the layer 13 is prevented from being reverse tapered in its cross section. Thus, a desired pattern can be obtained. |
