The outstanding properties of SiO2, which include high resistivity, excellent dielectric strength, a large band gap, a high melting point, and a native, low defect density interface with Si, are in large part responsible for enabling the microelectronics revolution. The Si/SiO2 interface, which forms the heart of the modern metal–oxide–semiconductor field effect transistor, the building block of the integrated circuit, is arguably the worlds most economically and technologically important materials interface. This article summarizes recent progress and current scientific understanding of ultrathin (<4 nm) SiO2 and Si–O–N (silicon oxynitride) gate dielectrics on Si based devices. We will emphasize an understanding of the limits of these gate dielectrics, i.e., how their continuously shrinking thickness, dictated by integrated circuit device scaling, results in physical and electrical property changes that impose limits on their usefulness. We observe, in conclusion, that although Si microelectronic devices...

Ultrathin (<4 nm) SiO2 and Si-O-N gate dielectric layers for silicon microelectronics: Understanding the processing, structure, and physical and electrical limits

This note presents the data on the dielectric breakdown of polydimethylsiloxane (PDMS) thin films with thicknesses from 2 to 14 μm between the silicon electrodes. The results demonstrate that there is a strong dependence of the breakdown field on both the electrode gap and shape. The breakdown fields range from 250 to 635 V μm−1, depending on the electrode geometry and gap, approaching 10× the breakdown fields for air gaps of the same size. The results are critical for understanding the performance limits of PDMS thin films used in the electromechanical microsystems.

https://iopscience.iop.org/article/10.1088/0960-1317/23/6/067001/pdf

Dielectric breakdown of PDMS thin films

We used heat treatment to intentionally introduce various structural defects in Czochralski silicon substrates. The type, size, and number density of the induced defects were surveyed with transmission electron microscopy, and the defects were then incorporated into SiO2 films (10–50 nm thick) during thermal oxidation in dry O2. The effect of the defects on dielectric strength of the SiO2 films was examined with a time zero dielectric breakdown method. Larger platelet oxygen precipitates caused greater decreases of the breakdown field, and precipitates smaller than the SiO2 film thickness did not appreciably reduce the breakdown field. Every large platelet oxygen precipitate incorporated in the SiO2 film caused a degradation. Octahedral oxygen precipitates caused little degradation. The breakdown field was higher than 7 MV/cm and did not depend much on the SiO2 film thickness and precipitate size. We discussed possible mechanisms for the degradation due to both kinds of precipitates. Oxidation‐induced sta...

Degradation of dielectric breakdown field of thermal SiO2 films due to structural defects in Czochralski silicon substrates

We report on the effects of the wet and dry oxidation processes on the interfacial roughness and time dependent dielectric breakdown (TDDB) characteristics of the poly-Si/SiO2/Si(100) trilayer. The interface roughness of the oxide layers buried under a thick poly-Si electrode has been investigated using an x-ray reflectivity technique. Analysis of x-ray reflectivity data for the trilayer samples and for a bare oxide film shows that interface roughness of poly-Si electrode/SiO2 interfaces depends on oxidation process while oxide layers have smooth SiO2/Si-subtstrate interfaces. TDDB of the SiO2 layer has also been observed to depend on the oxidation process, indicating that the interface roughness is a crucial factor affecting the TDDB characteristics. The wet oxidized SiO2 film is more stable to dielectric breakdown and has smoother interfaces than the dry oxidized sample.

Effects of oxidation process on interface roughness of gate oxides on silicon: X-ray reflectivity study

The present invention provides an insulating film formed on a surface of a substrate and made of a material containing oxygen, wherein a charge correction is carried out at a 1s peak position of a carbon adsorbed on a surface of the insulating film, and relative amounts between first to fourth peaks obtained when an oxygen 1s peak of the insulating film is decomposed by a same half width of 1.208 eV into a first peak at the oxygen 1s peak site obtained from an α-quartz crystal charge corrected similarly, and second to fourth peaks at positions of +0.87 eV, -0.35 eV and -0.83 eV, respectively from the oxygen 1s peak position, have relationship of that the third peak is higher than the second and fourth peaks, and the first peak is higher than the third peak, when a portion about 1 nm thick from the surface of the substrate of the insulating film is analyzed by a photoelectronic spectral method for an photoelectron extracting angle of 15° or less.

Insulating oxide film formed by high-temperature wet oxidation

This study investigated the dielectric breakdown characteristics of thermal oxide films grown by dry and wet oxidation. Oxide films grown by wet oxidation have lower B‐mode failure rates and higher B‐mode breakdown fields. On the other hand, the reliability of C mode of oxide films does not differ consistently between films grown by dry and wet oxidation. These results indicate that as‐grown defect causing B‐mode failure may shrink or be reduced during wet oxidation.

Takaaki Shiota

Papers

Effect of oxidation ambient on the dielectric breakdown characteristics of thermal oxide films of silicon