On the Origin of the Gate Oxide Failure Evaluated by Raman Spectroscopy. (31st March 2015)

• Record Type: Journal Article
• Authors: Yokogawa, Ryo; Tomita, Motohiro; Mizukoshi, Toshikazu; Hirano, Takehiro; Kusano, Kenichiro; Sasaki, Katsuhiro; Ogura, Atsushi
• Is Part Of: ECS transactions. Volume 66:Number 4(2015)
• Page Start: 237
• Page End: 243
• Publication Date: 2015-03-31
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; Electronic journals; Electronic journal; 541.37
• DOI: 10.1149/06604.0237ecst
• Languages: English
• ISSNs: 1938-5862

Abstract

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.