A.Y. Kang

Electron spin resonance observation of trapped electron centers in atomic-layer-deposited hafnium oxide on Si

We observed two paramagnetic defects in thin films of HfO2 on silicon with electron spin resonance. Both appear after photoinjecting electrons into the dielectric. Strong spectroscopic evidence links one spectrum to an O2− defect. A second spectrum is likely due to an Hf+3 related defect.

Electron spin resonance study of interface defects in atomic layer deposited hafnium oxide on Si

We report electron spin resonance (ESR) observation of interface defects at the HfO2/(111)Si boundary for HfO2 films deposited via atomic layer chemical vapor deposition using Hf(NO3)4 as a precursor. We observe several signals, dominated by one due to a silicon dangling bond at the Si/dielectric interface. This center is somewhat similar to, but not identical to, Si/SiO2 interface silicon dangling bonds. Comparison between ESR and capacitance versus voltage measurements suggests that these dangling bond centers play an important role in HfO2/Si interface traps.

Identification of the atomic scale defects involved in radiation damage in HfO/sub 2/ based MOS devices

We have identified the structure of three atomic scale defects which almost certainly play important roles in radiation damage in hafnium oxide based metal oxide silicon technology. We find that electron trapping centers dominate the HfO/sub 2/ radiation response. We find two radiation induced trapped electron centers in the HfO/sub 2/: an O/sub 2//sup -/ coupled to a hafnium ion and an HfO/sub 2/ oxygen vacancy center which is likely both an electron trap and a hole trap. We find that, under some circumstances, Si/dielectric interface traps similar to the Si/SiO/sub 2/ P/sub b/ centers are generated by irradiation. Our results show that there are very great atomic scale differences between radiation damage in conventional Si/SiO/sub 2/ devices and the new Si/dielectric devices based upon HfO/sub 2/.

Noninvasive nature of corona charging on thermal Si/SiO2 structures

The corona charging technique is widely utilized in commercial Si∕SiO2 semiconductor device reliability characterization tools and has been used in numerous electron spin resonance (ESR) experiments, by several groups to study defect centers in Si∕SiO2 system. A recent ESR study argued that the corona charging approaches are inherently unreliable and invasive. In this work we show that this is not the case. We find that low-field corona biasing is essentially noninvasive and thus can be utilized in both reliability characterization and fundamental studies of defect structures.

Reliability concerns for HfO/sub 2//Si (and (ZrO/sub 2//Si) systems: interface and dielectric traps

We report on electron photo-injection results in HfO/sub 2/ films using capacitance vs. voltage (CV) and electron spin resonance measurements. CV measurements indicate presence of pre-existing large capture cross section electron traps. Electron spin resonance measurements indicate trapped electrons in the form of O/sub -2/ superoxide ions. Another center, likely a Hf/sup +3/ center, is also observed.

Non-invasive nature of corona charging on thermal Si/SiO/sub 2/ structures

The corona charging technique is utilized in commercial semiconductor device reliability characterization tools and has been used in numerous electron spin resonance (ESR) experiments, by several groups to study defect centers in Si/SiO/sub 2/ system. A recent ESR study argues that the corona charging approaches are inherently unreliable and invasive. In this work we show that low-field corona biasing is essential non-invasive and thus can be utilized in both reliability characterization and fundamental studies of defect structures.

Reliability concerns for HfO/sub 2//Si devices: interface and dielectric traps

We have initiated a study of atomic scale defects which may play important roles in the reliability physics of a leading high dielectric constant/Si system: atomic layer deposition (ALD) HfO/sub 2/ on silicon. We have utilized capacitance versus voltage and electron spin resonance measurements to explore electrically active defects in ALD HfO/sub 2//Si device structures. We have subjected some of these structures to either vacuum ultraviolet (VUV) illumination or gamma irradiation. The VUV illumination and gamma irradiation flood the dielectric with electrons and holes. Post irradiation measurements most strongly indicate the presence of high densities of large capture cross section electron traps. Electron spin resonance measurements clearly indicate the presence of silicon dangling bond interface defects which are similar to but not identical to the silicon dangling bonds observed at conventional Si/SiO/sub 2/ interfaces.