Infineon Technologies Ag

Joern Luetzen

Albert Birner

Matthias Goldbach

Dirk Schumann

Steffen Breuer

To fabricate a vertical transistor, a trench is provided, the side wall of which is formed by a semiconductor substrate in single crystal form and the base of which is formed by a polycrystalline semiconductor substrate. A transition region is arranged between the side wall and the base. A semiconductor layer is deposited so that an epitaxial semiconductor layer grows on the side wall and a semiconductor layer grows on the base, with a space remaining between these layers. The semiconductor layers are covered with a thin dielectric, which partially limits a flow of current, and the space is filled. During a subsequent heat treatment, dopants diffuse out of the conductive material into the epitaxial semiconductor layer, where they form a doping region. The thin dielectric limits the diffusion of the dopants into the semiconductor substrate and prevents the propagation of crystal lattice defects into the epitaxial semiconductor layer.

Method for fabricating a vertical transistor in a trench, and vertical transistor

A method for producing a silicon-on-insulator layer structure on a silicon surface with any desired geometry can locally produce the silicon-on-insulator structure. The method includes formation of mesopores in the silicon surface region, oxidation of the mesopore surface to form silicon oxide and rib regions from silicon in single-crystal form; and execution of a selective epitaxy process that that silicon grows on the uncovered rib regions, selectively with respect to the silicon oxide regions. Rib regions remain in place between adjacent mesopores, this step being ended as soon as a predetermined minimum silicon wall thickness of the rib regions is reached, the uncovering of the rib regions, which are arranged at the end remote from the semiconductor substrate between adjacent mesopores. The method can be used to fabricate a vertical transistor and a memory cell having a select transistor of this type.

Method for forming an SOI substrate, vertical transistor and memory cell with vertical transistor

An insulation region, for example, an oxide collar, is formed in a trench structure for a DRAM by first widening a first trench region of the trench that is to be formed, in particular, a base region thereof. At least part of the widened region is then provided with a material region for the insulation region.

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Dresden, Germany

Joern Luetzen