| 摘要 |
PURPOSE:To improve a noise characteristic and an aging effect of constant voltage diode during a manufacturing process for the constant voltage diode to be assembled in an integrated circuit of double sides separation type by a method wherein the anode part is formed simultaneously with the upper separation area and the surface effect is eliminated. CONSTITUTION:N<-> epitaxial layer 3 is formed in P type Si substrate plate 1 having N<+> buried layer 2, and a constant voltage diode is formed in the area of the epitaxial layer 3 separated at its both surfaces. P<+> layer 8 forming anode of the diode is formed when the upper surface separation area 5 is diffused. Then, P<+> layer 6 is diffused at the same time as a forming of the base layer of the thermistor to be formed in other areas in the epitaxial layer 3, N<+> cathode area 7 is diffused in P<+> layer 6 during a step for forming the emitter to make the diode. Thereby, a performance of diode is defined as a junction characteristic between the areas 8 and 7 having a higher density than that of the layer 6, so that it may not be affected by the junction end surface of the substrate surface 10a. Thus, it is possible to improve a noise characteristic and prevent a drift as well as an aging of the reference voltage. |
