MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To improve a bipolar transistor in degree of integration as high as a MOS transistor by a method wherein the bipolar transistor and the MOS transistor are formed on the same semiconductor substrate in a self-aligned manner respectively. CONSTITUTION:An oxide film 23 and a poly-Si film 22 formed on a region I of a P-type Si substrate where a bipolar Tr is formed, a region II on which a P channel MOS Tr is formed, and a region III where an N channel Tr are selectively removed, and a resist pattern 30 is formed so as to cover the region III. A P-type impurity layer 31 is formed using the resist pattern 30 as a mask. Then, an opening is formed using a resist pattern 44 with an opening provided at its part corresponding to the base region of the bipolar Tr as a mask. P-type impurity 45 ions are implanted through the opening. Next, an outer base layer 46, a intrinsic base layer 47, and an emitter region 48 of the bipolar Tr are formed through a thermal treatment after the removal of the resist pattern 44. A region 48 is formed inside the base region in a self-aligned manner.