Uniform and perfectly V-shaped replacement fin structure
Publication Date: 2014-Jun-02
The IP.com Prior Art Database
Disclosed is a method to form Silicon Germanium (SiGe) fins and use those fins as etched replacements fins. The uniform, V-shaped fins at the bottom of the trench prevent Reactive Ion Etching (RIE) variation and reduce Anti-phase boundary defects in the subsequently grown III-V semiconductor.
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Uniform and perfectly V -
Alternate semiconductor materials, such as III-V semiconductors, are being considered as options for 7nm and beyond technology nodes. Those alternate semiconductor materials need to be on silicon for mainstream Very Large Scale Integration (VLSI).
All alternate semiconductor materials have a larger lattice constant than silicon . That leads to lattice mismatch between the alternate semiconductor and the silicon , and subsequently to very high strains being observed if the materials are grown directly on silicon. There are two methods to integrate III-V on silicon: blanket III-V growth and aspect ratio trapping. The lattice mismatch is overcome by either growth of very thick layers to allow relaxation of the alternate semiconductor material on silicon or by aspect ratio trapping (ART). The ART trenches trap misfit threading dislocations by stopping their propagation through growing the III-V in narrow trenches. An etched V-shape at the bottom of the trench helps reduce Anti -phase boundary defects in the subsequently grown III-V semiconductor.
There are several disadvantages to the current replacement fin scheme . Reactive Ion Etching (RIE) loading leads to recess variations of the fins, and the formed trenches have slightly different depths. The Reactive Ion Etched silicon surface on the bottom of the trench is not uniform (e.g., rounded, tilted, etc.), which leads to a non-symmetrical
V-shape at the bottom of the trench. This provides less benefit in avoiding Anti-phase boundary defects in subsequently grown III-V....