Interface Defects in HfO[sub 2], LaSiO[sub x], and Gd[sub 2]O[sub 3] High-k/Metal–Gate Structures on Silicon

Abstract

In this work, we present experimental results examining the energy distribution of the relatively high ͑Ͼ1 ϫ 10 11 cm −2 ͒ electrically active interface defects which are commonly observed in high-dielectric-constant ͑high-k͒ metal-insulator-silicon systems during high-k process development. This paper extends previous studies on the Si͑100͒/SiO x /HfO 2 system to include a comparative analysis of the density and energy distribution of interface defects for HfO 2 , lanthanum silicate ͑LaSiO x ͒, and Gd 2 O 3 thin films on ͑100͒ orientation silicon formed by a range of deposition techniques. The analysis of the interface defect density across the energy gap, for samples which experience no H 2 /N 2 annealing following the gate stack formation, reveals a peak density ͑ϳ2 ϫ 10 12 cm −2 eV −1 to ϳ1 ϫ 10 13 cm −2 eV −1 ͒ at 0.83-0.92 eV above the silicon valence bandedge for the HfO 2 , LaSiO x , and Gd 2 O 3 thin films on Si͑100͒. The characteristic peak in the interface state density ͑0.83-0.92 eV͒ is obtained for samples where no interface silicon oxide layer is observed from transmission electron microscopy. Analysis suggests silicon dangling bond ͑ P bo ͒ centers as the common origin for the dominant interface defects for the various Si͑100͒/SiO x /high-k/metal gate systems. The results of forming gas ͑H 2 /N 2 ͒ annealing over the temperature range 350-555°C are presented and indicate interface state density reduction, as expected for silicon dangling bond centers. The technological relevance of the results is discussed.

New Semiconductor Devices

“…The typical peaks at 0.2-0.3 eV from the band edges exist also in the case of the high-k materials (Fig. 16) and the mechanism for electron capture is of multiphonon type as earlier found for P b centers at SiO 2 /Si interfaces treated by gamma irradiation [20,21]. This phenomenon was demonstrated to have the same physical background as that leading to an exponential energy dependence of capture cross-sections as shown in Fig.…”

Determination of interface state density in high-k dielectric-silicon system from conductance-frequency measurements

“…The physical nature of surface states at the high k − dielectric -semiconductor interface is still being debated. In addition to silicon dangling bonds, oxygen vacancy inside the high k − oxide, isolated metal atom in the interlayer, or the metal atom bonded to silicon substrate can also make a contribution to the measured interface state density [4]. But the energy position of peaks in the interface state distribution and similarity of the spectra for different high oxides allow to make a conclusion that the main defects responsible for k − formation of electrically active states at the interface are silicon dangling bonds.…”

“…Application of conductance-frequency spectroscopy to characterization of high -oxide/silicon interface and possible nature of interface defects of several high k − k − systems were discussed in [4,[8][9][10]. However, this technique was not commonly used for the study of interface properties in the case when a high leakage current flows through the dielectric film.…”

Structural analysis, elemental profiling, and electrical characterization of HfO2 thin films deposited on In0.53Ga0.47As surfaces by atomic layer deposition

“…This is characteristic of an interface defect response where the interface state distribution exhibits a peak at a specific energy in the band gap at the dielectric/semiconductor interface. [21][22][23] For the case of inversion at the HfO 2 / In 0.53 Ga 0.47 As interface with an associated minority carrier response, the capacitance should acquire a constant value in inversion, where the magnitude of the capacitance increases with decreasing ac signal frequency. The inset of Fig.…”