Patent ID: 11888024
Assignee: INFINEON TECHNOLOGIES AG
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 18:
19. A method of forming a semiconductor device, the method comprising:
forming a trench in a semiconductor body at a first surface of the semiconductor body;
at least partially filling the trench with a filling material, the filling material having a bottom side and a top side;
introducing dopants into a portion of the filling material to form a doped filling material, wherein the dopants have a first diffusion coefficient relative to the filling material and have a second diffusion coefficient relative to the semiconductor body, wherein the first diffusion coefficient is greater than the second diffusion coefficient, and wherein a diffusion coefficient ratio of the first diffusion coefficient to the second diffusion coefficient is greater than 10 to suppress out-diffusion of the dopants from the doped filling material to the semiconductor body during a first thermal processing;
applying the first thermal processing to the doped filling material, the first thermal processing configured to spread the dopants within the doped filling material along a vertical direction between the bottom side and the top side of the doped filling material by a diffusion process, thereby shaping a vertical doping profile of the dopants within the doped filling material, wherein the diffusion coefficient ratio suppresses out-diffusion such that the dopants are confined to within the trench and substantially do not diffuse from the doped filling material into the semiconductor body during the first thermal processing; and
subsequent to applying the first thermal processing, applying a second thermal processing to the semiconductor body configured to cause diffusion of the dopants from the doped filling material having the shaped vertical doping profile into a region of the semiconductor body adjoining the trench, wherein the diffused dopants from the filling material cause counter-doping of the semiconductor body, and
wherein the filling material is at least one of silicon oxide or polycrystalline silicon.