On the Origin of the Gate Oxide Failure Evaluated by Raman Spectroscopy

Abstract

The metal-oxide-semiconductor-field-effect-transistor (MOSFET) has been miniaturized for the high performance large-scale integrated-circuit (LSI). However, in the ultimately miniaturized MOSFET, the gate oxide failure with high leakage current is inevitable. In this study, we evaluated the origin of the gate oxide failure by Raman spectroscopy in conjunction with optical beam induced resistance change (OBIRCH) analysis. MOS capacitors were used as the samples. The 2.8 nm thick gate oxinitrid insulator film and the poly-Si gate electrode layer were formed on a P type Si substrate. The cobalt (Co) silicide film was formed on the poly-Si electrode. The SiH4 flow rate was 150 sccm or 350 sccm. The gate oxide integrity was evaluated by the test element group (TEG) measurements. As a result, Raman intensity increased at the failure position compared with the other positions in the sample deposited with 150 sccm of SiH4 flow rate. We consider that higher Raman intensity at the gate oxide failure positions reflects the irregular structure of poly-Si. Furthermore, the Raman peaks at failure positions shifted toward the lower wavenumber while the FWHMs are approximately constant with other positions. Thus, we found that there is no difference in the crystallinity of the poly-Si. The origin of the gate oxide failure was high tensile strain in the gate poly-Si electrode. In conclusion, we have successfully evaluated the gate oxide failure by Raman spectroscopy with a quasi-line excitation source.

Crystallinity Evaluation of Low Temperature Polycrystalline Silicon Thin Film Using UV/Visible Raman Spectroscopy

“…A quasi-line excitation (with length of approximately 100 μm) was used to perform one dimensional Raman spectroscopy measurement at the same time [10][11][12]. Therefore, 512 points Raman spectra from every 200 nm were obtained simultaneously for each sample.…”

Evaluation of Laterally Graded Silicon Germanium Wires for Thermoelectric Devices Fabricated by Rapid Melting Growth

“…The Ge fraction x and strain were estimated using the equation proposed by Pezzoli et al [10,11]. A quasi-line excitation (approximately 100 μm) was used to measure one dimensional Raman spectra at the same time [12][13][14]. Excitation source of visible laser ( = 532 nm) was used and focal length of the Raman spectrometer was 2,000 mm.…”

Evaluation of controlled strain in silicon nanowire by UV Raman spectroscopy

“…In general, the FWHM of the crystalline Si Raman spectrum is approximately 3.0 cm −1 and reflects the crystal quality. 30,31) This implies the effect of plasma CVD damage during TEOS deposition and oxygen vacancy. As described above, the beam spot size of the Raman measurement significantly exceeded the Si NW width.…”