SEMICONDUCTOR DEVICE

• Main Author: MORITA NAOYUKI
• Format: Patent
• Language: English
• Published: 27.02.1990
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

PURPOSE:To obtain a semiconductor device equipped with an electrostatic protecting circuit assuring a sufficient electrostatic breakdown strength by a method, in an integrated circuit constituted by using MOSFET's having LDD structure, an N<+> region is formed by using phosphorus impurity, only in an MOSFET constituting the electrostatic protecting circuit. CONSTITUTION:On the same semiconductor substrate 1, the following are arranged; an internal circuit 2 formed by MOSFET's having LDD structure to relieve drain electric field, and an electrostatic protecting circuit 3 to protect the internal circuit 2 from external abnormal signals. The source.drain of the LDD transistors of the above internal circuit 2 has high concentration diffusion regions 10, 11 of arsenic. The source.drain region of the LDD transistor in the above electrostatic protecting circuit 3 has high concentration diffusion regions 12, 13 of phosphorus. Since the average range distance to the semiconductor substrate 1 and the diffusion coefficient of arsenic and those of phosphorus are mutually different, the N<+> diffusion layer of the electrostatic protecting circuit 3 is about two times as deep and about one-half wide as the N<+> diffusion layer of the internal circuit 2. Thereby the electrostatic breakdown strength is remarkably improved.