| AVS 62nd International Symposium & Exhibition | |
| Materials Characterization in the Semiconductor Industry Focus Topic | Tuesday Sessions |
| Session MC-TuM |
| Session: | Characterization of 3D structures |
| Presenter: | Anita Madan, GLOBALFOUNDRIES |
| Authors: | A. Madan, GLOBALFOUNDRIES S. Mochozuki, IBM Albany Nanotech Center C. Murray, IBM, T. J. Watson Research Center D. Cooper, CEA, LETI, MINATEC Campus, France Y. Wang, GLOBALFOUNDRIES W. Weng, GLOBALFOUNDRIES T. Pinto, GLOBALFOUNDRIES |
| Correspondent: | Click to Email |
Strain engineering has been adopted as a key element for scaling high performance complementary metal-oxide-semiconductor (CMOS) devices. Complex 3D structures (FinFETs) have been introduced for the 14 nm technology node and beyond. Typically, strain is introduced by replacing the Si channel with SiGe for pFET devices. Characterization of strain in the fins is challenging due to the complexity of their three-dimensional geometries and their nanoscale dimensions.
In this paper, we present the methodology developed to characterize strain and crystallinity in both strained SiGe FinFET structures and FinFET structures with epitaxial embedded SiGe (eSiGe). We compare 2 complementary techniques used for characterization of strain on 3D fins. High Resolution X-ray Diffraction techniques with a spot size and a spatial resolution of 50 to 200 microns are non-destructive and the signal (averaged over many fins) is sensitive to defectivity, strain and Ge content. On the other hand, Transmission Electron Microscopy (spot size 0.3 – 5nm) is a destructive technique, dependent on the lamella thickness, and gives localized information on a few fins.
All measurements were made on blanket and fin array pads on specially designed macros. For XRD measurements, strain was evaluated using peak position information from the XRD Reciprocal Space Maps collected both parallel and perpendicular to the fin arrays. Measurements show that the stress in the SiGe fins is uniaxial – the SiGe fins are fully strained along the direction of the fins. The SiGe is partially relaxed perpendicular to the fins – the amount of relaxation dependent on the %Ge and the height of the SiGe fins. Advanced TEM analytical techniques (Nano beam diffraction, Dark Field holography and Energy-dispersive X-ray spectroscopy) were used to map the strain and %Ge over the height and the width of the SiGe fins. There was good correlation between the average strain and %Ge as determined from the TEM and XRD techniques. Results of the measurements will be compared with theoretical modeling, which is used to quantify the triaxial stress tensor components based on the experimentally determined lattice parameter values.
The advent of new HRXRD tools with 1D detectors and high intensity sources enable these measurements to be made over a couple of hours. Since XRD techniques are non-destructive, we will also discuss how this methodology can be easily adapted as in-line metrology to monitor the change in strain with processing.
This work was performed by the Research and Development Alliance Teams at various IBM Research and Development Facilities.