High-voltage-resistant MOS transistor, and corresponding manufacturing process

摘要

A MOS transistor (1) capable of withstanding relatively high voltages is of a type integrated on a region (3) included in a substrate of semiconductor material, having conductivity of a first type (N) and comprising a channel region (7) intermediate between a first active region of source (4) and a second active region of drain (5). Both these regions (4 and 5) have conductivity of a second type (P) and extend from a first surface (6) of the substrate. The transistor (1) also has a gate which comprises at least a first polysilicon layer (8) overlying the first surface (6) at at least said channel region (7), to which it is coupled capacitively through a gate oxide layer (9). According to the invention, the first polysilicon layer (8) includes a mid-portion (13) which only overlies said channel region (7) and has a first total conductivity (C1) of said first type (N), and a peripheral portion (14) with a second total conductivity (C2) differentiated from said first total conductivity (C1), which peripheral portion partly overlies said source and drain active regions (4 and 5) toward said channel region (7).