Interface States and P[sub b] Defects at the Si(100)/HfO[sub 2] Interface

Abstract

Defects present at the Si(100)/HfO 2 interface are analyzed using a combination of electron spin resonance ͑ESR͒ and frequencydependent impedance analysis. The 3.4 nm HfO 2 layers were formed by injection metalorganic chemical vapor deposition on boron-doped silicon ͑100͒ substrates. ESR spectra indicate the presence of P b0 defects ((5.0 Ϯ 0.4) ϫ 10 12 cm Ϫ2 ), while analysis of the low-frequency ͑20 Hz͒ capacitance-voltage ͑CV͒ response indicates a defect density of (5.8 Ϯ 1.1) ϫ 10 12 cm Ϫ2 , between 0.1 and 0.56 eV above the valence bandedge (E v ), with the peak density located at E v ϩ 0.28 eV. Analysis of conductance data reveals an interface state density of (8.4 Ϯ 2.1) ϫ 10 12 cm Ϫ2 , with a peak density observed at E v ϩ 0.27 eV. These results provide a link between the density of P b centers measured by ESR, and the electrical active defects measured from CV and conductance analysis. This provides an explanation for the nonideal, frequency-dependent features in the region between accumulation and strong inversion for high-MOS structures.One of the major challenges associated with the continued scaling of silicon based metal oxide silicon ͑MOS͒ technology is the requirement for high dielectric constant ͑high-͒ materials to replace SiO 2 as the gate layer of MOS field-effect transistors ͑MOSFETs͒. High-materials research is driven by the need to reduce gate insulator leakage current densities while maintaining the capacitance per unit area of the gate stack. A wide range of metal oxides are currently being studied, including ZrO 2 , HfO 2 , Al 2 O 3 , Pr 2 O 3 as well as metal silicates and aluminates. 1 The understanding and control of the properties of the interface between silicon and the high-material is one of the most important issues for the successful integration of high-films as the gate oxide layer of MOSFETs.Previous studies based on electron spin resonance ͑ESR͒ have established that for Al 2 O 3 and ZrO 2 layers deposited on silicon by atomic layer chemical vapor deposition ͑ALCVD͒, the dominant ESR active interface defects are the P b silicon dangling bond defects 2 detected at the Si͑100͒/insulator interface. 3,4 The density of the P b0 and P b1 centers were characteristic of an SiO 2 film grown at a low temperature (ϳ300°C). It was necessary to expose the samples to UV irradiation at 8.48 eV for photodissociation of hydrogen from the interface defects, to observe the P b centers. An ESR analysis of HfO 2 films deposited on Si͑111͒ by ALCVD using a Hf(NO 3 ) 4 precursor, also indicated an interface dominated by silicon dangling bond centers, albeit with some dissimilarities as compared to the standard high-temperature Si(111)/SiO 2 interface, 5 as outlined previously. 2 In relation to the electrical activity of the interface defects in the Si͑100͒/high-system, it has been reported that capacitance-voltage ͑CV͒ characteristics have a nonideal behavior, with a frequency-dependent feature in the region between accumulation and strong inversion for ZrO 2 and HfO 2 MOS structures. 5-9 Modeling ...

Observation of peripheral charge induced low frequency capacitance-voltage behaviour in metal-oxide-semiconductor capacitors on Si and GaAs substrates

“…In the case of the n-type NiSi/GdSiO x /nSi sample, it is clearly visible as a frequency dependent distortion in the multi-frequency CV responses plotted in at $E v þ 0.37 eV and 2.6 Â 10 12 cm À2 eV À1 at $E v þ 0.82 eV. These density values and the peak energy positions are again consistent with those reported for P b dangling bond defects 14,[20][21][22][23][24][25][26][27] and are expected as the samples did not receive a forming gas anneal. It is important to emphasize that the interface states do not contribute to the inversion response discussed in this paper.…”

“…The peak energy positions are consistent with those expected for P b dangling bond defects, as reported extensively in the literature. 14,[20][21][22][23][24][25][26][27] It is important to state that the peripheral inversion effect is not unique to the MgO/Si system or the FUSI processing used for the MgO sample set. To illustrate this, results are now presented showing evidence of peripheral inversion effects for a different oxide/Si MOS system, and where very different processing steps were used in the device fabrication, as described earlier in the experimental section.…”

Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation

“…19 It is interesting to note that in Fig. 1 the FGA not only reduces the interface state density but also removes the stretch out.…”

“…The method of extraction first assumes that the HRTEM images give accurate thickness estimates for all three samples ͓sample A: t͑SiO x ͒ =6 Å, t͑HfO 2 ͒ = 37 Å; sample B: t͑SiO x ͒ =19 Å, t͑HfO 2 ͒ = 37 Å; sample C: t͑SiO x ͒ =29 Å, t͑HfO 2 ͒ =40 Å͔. The second assumption is that the k value for the hafnium oxide layer falls within the range of [16][17][18][19][20][21][22][23][24][25]. The third assumption is that the k value for the IL is in the range of 3.9-8.0.…”

Pre-doping effects on Ni fully silicided metal gate on SiO2 dielectric

“…Therefore, ion implanted sample with a spike activation anneal will show a high-density characteristic D it peak, which can be eliminated by FGA. The physical origin of these induced interface traps may be determined more exactly by further analysis with other measurement tools such as electron paramagnetic resonance [18,21,[23][24][25].…”