| 摘要 |
PURPOSE:To obtain a bipolar semiconductor device of high integration high speed in a high yield by forming by self-alinging an external base and an emitter layer. CONSTITUTION:A P<-> type base 7 is formed on the part of an N type collector layer 1, a P type polysilicon layer 3 and an Si3N4 film 4 are superposed, and a hole 5 is opened. The layer 3 is sidewisely etched from the hole 5 to expand the hole 5 to a hole 6, thereby forming an overhang 4a of the film 4. A heat treatment is executed in O2, a P type impurity is diffused from the layer 3 to form a thick film 9 on the base 7, a P<-> type base 8 surrounded by the base 7 and the end of the film 3 under the overhang 4a. The oxidized thin film on the layer 8 is removed with HF series etchant or reactive ion etching to expose the base 8, and an oxidized film 9 is allowed to remain under the overhang 4a. Then, an N type polysilicon pattern 10 is formed, a heat treatment is executed with the pattern 10 as a diffusion source, thereby forming an N<+> type emitter layer 11. According to this configuration, the external base and and N<+> type emitter are self-aligned without contact, thereby obtaining a bipolar semiconductor device of high integration and high speed in a high yield. |
