Evaluation of Ge Concentration using Lattice Deformation Measurement of SiGe FinFET
Publication Date: 2015-May-26
The IP.com Prior Art Database
Disclosed is a method to evaluate the Ge concentration using lattice deformation measurement of Silicon Germanium (SiGe) Fin Field Effect Transistor (FinFET).
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Evaluation of Ge Concentration using Lattice Deformation Measurement of SiGe
Typical lattice deformation provides information in two directions (e.g., Fin Field Effect Transistor (FinFET)  in -220 (horizontal) and 0 02 (vertical) direction). Information obtained from Silicon Germanium (SiGe) objects deposited on silicon enables the determination the Ge content inside the SiGe Fins. A case corresponding to an unrelaxed SiGe FinFET with  channel was developed, with the following conditions:
No lattice deformation with respect to substrate Si lattice, SiGe fully is trained
Horizontal lattice deformation = 0 à fully strained
Vertical lattice deformation depends on the Ge content and the vertical Poisson ratio of the SiGe film
Figure 1: Calculus of mechanical strain from lattice deformation measured by Nanobeam Diffraction technique
Nanobeam Diffraction (NBD) lattice deformation is related to SI lattice. No strain in the SiGe layer means it is fully stressed with no mechanical relaxation. Mechanical strain is the initial strain/stress in SiGe (linked to the Ge content and lattice mismatch) compared to unstressed silicon. According to the calculus above, to obtain the strain in SiGe from lattice deformation, there is a need to determine the fully relaxed SiGe lattice constant
, so there is a need to know the Ge content x with
Figure 2: The schematic of SiGe Fin on Si substrate
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NBD or any other technique provides the lattice deformation in z and y direction ex and ey, whic...