Failure physics of ultra-thin SiO₂gate oxides near their scaling limit

Abstract

The present status and near future perspectives for ultra-thin SiO 2 gate oxide films are examined. With the ultimate physical thickness limit of 1 nm on the near horizon, leakage current and reliability issues are discussed. Our choice is to highlight the physics of the involved phenomena because we are convinced that a detailed knowledge of the involved physics is required for any accurate reliability forecasting exercise. The hypothesis of equilibrium conditions in the modelling of tunnel injection through ultra-thin oxide films is discussed. The present knowledge of the physics of degradation and breakdown is briefly reviewed, with particular emphasis on the open problems. The idea that the wear-out is a fluency-and energy-driven process is defended. The problem of monitoring the degradation of the oxide is addressed. The limitations of using indirect electrical monitors are presented and a method based on the analysis of statistical breakdown data is discussed. The status of the different breakdown modes (soft and hard) is considered. In this regard, it is concluded that the study of the mechanisms that control the severity of the breakdown events is one of the priorities in the field of ultra-thin oxide reliability. Finally, some attention is paid to the local probe techniques required for the atomic-scale characterization of the oxide properties.

Defect evolutions with different temperature injections in MOSFETs

“…Experiments on 5.4 nm thick oxide samples reproduce results on 9.5 nm thicker samples at 300 K but with smaller creation sections. These defects are then compatible with those presented by the trap involved in the SILC for thinner samples (Blo¨ch and Stathis, 1999; Stathis and DiMaria, 1999; Sune´ et al , 2000).…”

“…Slow‐state traps are oxide defects in the interfacial area and the term P a centres for vacancies in interfacial location are also found (Kropman et al , 2000). The term hydrogen bridge is also proposed (Blo¨ch and Stathis, 1999; Stathis and DiMaria, 1999; Sune´ et al , 2000), that is to say a defect, which involves hydrogen and a vacancy. However, the tradition separation between oxide and interface defects is insufficient and even misleading.…”

A study of soft and hard breakdown - Part I: Analysis of statistical percolation conductance

“…It is also clear from the experimental data that postbreakdown conductivity depends weakly on the thickness of the oxide. Such a systematic, albeit weak, dependence of the percolation conductance on thickness may require refinement of the ballistic quantum-point-contact model, which has been proposed, in [19] and [32], as an explanation for the power-law behavior of the -characteristics. To further validate the percolation model discussed in Section III-A, we plot as a function of ( Fig.…”

Scaling and disorder analysis of localI–Vcurves from ferroelectric thin films of lead zirconate titanate

“…Current sensing scanning probe microscopy, where a metal-coated tip acts as one of the electrodes in the two-terminal transport measurement, is emerging as a potent method to investigate electron transport properties of such materials, because the localization of the probed volume to less than tens of nanometers allows one to differentiate between intrinsic and defectmediated transport [10,11]. Examples of new phenomena discovered and characterized by conducting atomic force microscopy (cAFM), often in combination with other types of scanning probe microscopy, include polarizationcontrolled tunneling across ferroelectric surfaces [7] and tunnel junctions [5,6], local conductivity of ferroelastic domain walls in multiferroic oxides [12], filamentary conduction through perovskite oxides [13], heterogeneity and breakdown of ultrathin dielectrics [14], local manipulation of twodimensional electron gas at perovskite interfaces [15] and local variations in catalytic activity of ionic membranes for fuel cells [16].…”