| 摘要 |
PURPOSE:To form a pattern having high accuracy, and to improve the electrical characteristics of a device by using photo-resists of two kinds as ones for a photolithography process and preventing the formation of an undercut by utilizing the removing characteristics of the photo-resists. CONSTITUTION:Base section diffusion regions 27, 28 having low resistance and high resistance are formed in an epitaxial layer region 24' in a semiconductor substrate 21. A pattern of a negative type photo-resist 29 is formed, and an silicon oxide film 22 is etched until it is brought close to the thickness of the silicon oxide film in a section A to which an emitter section is shaped. The negative type photo-resist 29 is coated with a positive type photo-resist 31, resist patterns 32, 33 are formed, and the photo-resist 29 in the section A is removed through a plasma ashing method until the silicon oxide film 22 is exposed. When the exposed sections of the silicon oxide film 22 are etched, fine patterns can be formed without under cuts because film thickness is approximately equal, and an opening section 34 for the emitter section and a stepped opening 35 are formed. |
