Process for forming an epitaxial layer

Abstract

The invention relates to a process for forming an epitaxial layer, especially to a process, comprising the steps that a layer of a semiconductor material is epitaxially grown on a single-crystal semiconductor structure (S, D) and on a polycrystalline semiconductor structure (G). The epitaxial layer is then etched in order to preserve a non-zero thickness of said material on the single-crystal structure(S, D) and a zero thickness on the polycrystalline structure. The process of growth and etch is repeated, with the same material or with a different material in each repetition, until a stack of epitaxial layers on said single-crystal structure (S, D) has reached a desired thickness (EE).

Description

Technical field [0001] The present invention relates to microelectronics, and particularly to the formation of epitaxial layers of semiconductor materials, especially the formation of source and drain regions of transistors such as fully depleted transistors fabricated on silicon-on-insulator (SOI) substrates The epitaxial layer. Background technique [0002] The epitaxial growth step can be used to control the electrical characteristics of the source and drain regions of the insulated gate transistor. The level of dopants present in these single crystal regions can be specifically controlled by introducing dopants into the epitaxial silicon layer. It is also possible to introduce germanium atoms or carbon atoms in order to modify the mechanical strain in the epitaxial layer and in order to increase the mobility of charge carriers in the source and drain regions. [0003] In addition, traditionally, the gate of a transistor includes at least one polysilicon layer that may be depo...

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Problems solved by technology

[0008] Even so, using a hard mask is expensive and difficult to implement

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