Ultra-thin Oxide Reliability Research Articles

Reliability of ultrathin gate oxides for ULSI devices

Abstract Ultrathin gate oxide, which is essential for low supply voltage and high driving capability, is indispensable for the continued scaling of ULSI technologies towards smaller and faster devices. Needless to say, the reliability of ultrathin oxide is of major concerns in the manufacturing of the state-of-the-art metal-oxide-semiconductor devices. This paper reviews the reliability issues regarding ultrathin gate oxide for present and future ULSI technologies. Issues including gate leakage current, time-dependent dielectric breakdown, poly-gate depletion, boron penetration, and plasma process-induced damage will be addressed. Several techniques such as nitrided oxide and alternative processes, which are proposed to improve gate oxide reliabilities, are also discussed.

Improvement on properties and reliability of ultra-thin silicon oxide (3–5 nm) grown by microwave plasma afterglow at the low temperatures using mixtures of N 2O and O 2

Ultra-thin silicon oxides (4 nm) with excellent quality were grown by using mixture of N 2O and O 2 plasma in a microwave afterglow plasma oxidation system. The electrical breakdown fields of oxide grown with a mixture of N 2O and O 2 plasma are comparable with that of conventional thermally grown oxides. The interface state densities are lower and charge to breakdown are higher than that of oxide grown in traditional thermal furnace. The optimal interface state density (∼3×10 10 cm −2 eV −1) could be achieved by tuning the N 2O/O 2 ratio. The oxides grown with a lower microwave power and a lower gas flow rate possess lower interface state density. Higher value of charge to breakdown could be found in oxides grown at low gas flow rate. Resistance to tunneling current stress increased as the ratio of N 2O/O 2 in plasma is higher. All these improvements could be attributed to the incorporation of nitrogen into oxides grown at lower temperatures in our novel system.

Properties and reliability of ultrathin oxides grown on four inch diameter silicon wafers by microwave plasma afterglow oxidation

We have successfully grown ultrathin oxides on large area of silicon wafers by the microwave plasma afterglow oxidation method. Analysis of the Fourier transform infrared spectra indicates that the general bonding structures of the ultrathin oxides grown by microwave plasma afterglow oxidation at 700 °C could be identical to those grown by dry O2 thermal oxidation. Electrical property measurements (e.g., time-zero dielectric breakdown and time-dependent dielectric breakdown) are also investigated. Based on our results, we conclude that microwave plasma afterglow oxidation is a useful method for the preparation of large area ultrathin oxide films on silicon substrates.

Comparison of performance and reliability between MOSFETs with LPCVD gate oxide and thermal gate oxide

Summary form only given. The time-dependent dielectric breakdown (TDDB) characteristics and MOS properties and reliability of ultrathin (65-AA) LPCVD silicon oxides annealed in N/sub 2/ ambient have been studied and compared with those of thermal oxide of identical thickness. It is shown that the devices with CVD oxide have much lower defect densities and are less susceptible to interface state generation, charge trapping, and transconductance degradation than those with thermal oxide. The results indicate that CVD oxide is a promising candidate for future ULSI technology, for which reliable ultrathin gate dielectrics are required. >