SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF

PURPOSE:To form a transistor having a thick collector layer and a transistor having a thin collector layer on the same substrate, and to form a collector wall by shallow diffusion without surrounding a base layer by forming in advance a step on a portion formed with the thick collector layer and then forming a thin collector layer. CONSTITUTION:An oxide film 2 is patterned on a portion to form a thick collector layer on a substrate 1, and silicon-etched. Then, an N-type high density diffused layer 4 is formed on the surface, an oxide film is patterned on a portion to form a thin collector layer, a separating silicon portion is removed and oxidized thereafter similarly to the conventional manufacturing method, a polysilicon 6 is laminated in a V-shaped groove 3 removed with the silicon, the back surface is polished to form a silicon island of a transistor. Here, the collector wall of a transistor having a thin collector wall is formed only on one side.