Epitaxial growth of doped film for source and drain regions

摘要

Embodiments of mechanisms for epitaxially growing one or more doped silicon-containing materials to form source and drain regions of finFET devices are provided in this disclosure. The dopants in the one or more doped silicon-containing materials can be driven into the neighboring lightly-doped-drain (LDD) regions by thermal anneal to dope the regions. The epitaxially growing process uses a cyclical deposition/deposition/etch (CDDE) process. In each cycle of the CDDE process, a first and a second doped materials are formed and a following etch removes most of the second doped material. The first doped material has a higher dopant concentration than the second material and is protected from the etching process by the second doped material. The CDDE process enables forming a highly doped silicon-containing material.

主权项

1. A method comprising:
providing a semiconductor substrate with fins and gate structures; forming spacers on each of the gate structures; etching portions of the fins not covered by the gate structures to form recesses in the fins below exposed surfaces of isolation structures between the fins, wherein the recesses are below surfaces of isolation structures neighboring the fins; and forming doped source and drain regions for the gate structures by epitaxially growing at least one silicon-containing material from the recesses, wherein a cyclic deposition-deposition-etch (CDDE) process is used for the epitaxially growing, and wherein each cycle of the CDDE process forms a first doped epitaxial material during a first deposition step and a second doped epitaxial material during a second deposition step subsequent to the first deposition step, a first dopant concentration of the first doped epitaxial material being different from a second dopant concentration of the second doped epitaxial material, wherein a portion of the second doped epitaxial material is removed an etch process in each cycle of the CDDE process.