SSRM and SCM Observation of Enhanced Lateral As- and BF2-diffusion Induced by Nitride Spacers
- PDF / 413,645 Bytes
- 12 Pages / 595 x 842 pts (A4) Page_size
- 76 Downloads / 144 Views
SSRM and SCM observation of enhanced lateral As- and BF2-diffusion induced by nitride spacers. P. Eyben 1, N. Duhayon , C. Stuer , I. De Wolf, R. Rooyackers, T. Clarysse, W. Vandervorst and G. Badenes IMEC vzw, Kapeldreef 75, 3001 Leuven, Belgium ABSTRACT State-of-the-art semiconductor devices require an accurate control of the complete twodimensional dopant distribution. The routine use of process simulators to predict the envisaged distributions and their resulting accuracy, is strongly linked to the physical models contained in these programs as well as their calibration. Whereas SIMS and SRP have been used extensively for the calibration of 1D-profiles, calibration of 2D-profiles has been very limited. In this work, we report some results obtained with the 2D-profiling techniques SSRM (Scanning Spreading Resistance Microscopy) and SCM (Scanning Capacitance Microscopy ) for the study of two-dimensional effects on diffusion. In particular, we discuss the role of the nitride spacer on the lateral diffusion of arsenic and boron. Using series of transistors with different nitride spacers with or without TEOS-liners, a strong dependence between the lateral diffusion and the nitride spacer thickness can be observed using SSRM and SCM. The process flow eliminates the possible contribution of Transient enhanced diffusion (TED) as a dominant mechanism. At the same time an enhancement of the lateral stress underneath the spacers has been observed with CBED and Raman, suggesting a correlation between the lateral diffusion and the nitride spacers. The enhanced diffusion of As and B is strongly linked to the spacer size whereby the differences in enhancement suggest that the proximity of the dopants to the stress field field region is an important parameter.
1.
Experimental 1.1.
Two-dimensional carrier profiling
In this study extensive use has been made of Scanning Spreading Resistance Microscopy (SSRM) to probe the two-dimensional carrier profile [1][2]. SSRM is an electrical characterization technique based on the Atomic Force Microscope (AFM) whereby a very small conductive tip is used to measure the local spreading resistance. Scanning of the tip over the cross section of the sample provides a two-dimensional map of the local spreading resistance with a spatial resolution set by the tip radius (typically 10-15 nm). The attractiveness of SSRM lies in its robustness (very insensitive to sample preparation) and ease of quantification. In fact a straight conversion of spreading resistance (SR) to local resistivity (ρ) can be made using R=ρ/4a (with a the tip radius) which provides an 1
[email protected]
B2.2.1
0.5 µm
0 µm 0.5µm
7RSR6650 165 nm
670 nm
165 nm 6650
430 nm
0 µm 0.5µm
6&0 430 nm
0 µm
1.25µm
Figure 1. Picture of an NMOS transistor showing SSRM topography information (top) as well as SSRM (middle) and SCM (bottom) electrical information. An excellent correspondence between SCM and SSRM can be observed.
accuracy of already a factor 2. More refined data treatment is required to correct for twodimens
Data Loading...
