| 摘要 |
PURPOSE:To selectively make the channel width of one MOS transistor smaller than that of the other MOS transistor so as to lessen a semiconductor device in cell area by a method wherein a mask pattern used for forming the channel of the former MOS transistor is selectively thinned. CONSTITUTION:At least, two types of mask layers different from each other in line width, a first mask layer 48a and a second mask layer 48b, are formed on the surface of a silicon semiconductor substrate 46. Then, only the second mask layer 48b larger than the other in line width is covered with a resist film 49, and the substrate 46 is subjected to an isotropic etching treatment with hydrofluoric acid or the like, whereby the pattern of the first, mask layer 48a not covered with the resist film 49 is selectively thinned. Then, the resist film 49 is removed, and then the mask layers 48a and 48b serve as resist masks for etching the surface of the semiconductor substrate 46 for the formation of semiconductor layer forming mesas 28a and 30a. An insulating film layer 40 is used as a stopper, and a cutting and polishing process is carried out so as to form a semiconductor thin film layer correspondent to the mesas 28a and 30a. |
