Takao Yasue

Dielectric breakdown of silicon oxide studied by scanning probe microscopy

The applicability of scanning probe microscopy in the dielectric breakdown characteristics of silicon oxide has been demonstrated. Our study demonstrates that the measurement on the oxide is free from the effect of trapped charge created by Fowler–Nordheim tunneling when a sufficient distance is maintained between the measuring points. In this condition, for a 13-nm-thick oxide, the dielectric breakdown voltages were found to be so uniform as to fluctuate only 1%. We applied this method to oxides on the wafers from two different vendors, and found that the dielectric breakdown strength of the oxide depends on the difference on the Si substrates. We also applied this method to a square oxide pattern surrounded by a field oxide, and the result was that the dielectric breakdown strength of the oxide on the edge is lower than the one in the center.

I–V characteristics of modified silicon surface using scanning probe microscopy

Using scanning probe microscopy, we have modified a silicon surface and measured its current–voltage (I–V) characteristics. In the modified area, both an increase in film thickness and a decrease in current caused by field-induced oxidation (FIO) have been observed. The I–V characteristics of the FIO film shows a good fit to a Fowler–Nordheim (FN) tunneling current model. The barrier height determined by a FN plot shows a good agreement with that of conventional metal–oxide–semiconductor structure with thermal thick silicon oxide.

Apparatus and method for analyzing foreign matter on semiconductor wafers and for controlling the manufacturing process of semiconductor devices

A device for analyzing foreign matter on semiconductor wafers is provided, which is capable of analyzing a great deal of foreign matter rapidly without requiring the higher level decision capabilities of a skilled analyst. The device for analyzing foreign matter on semiconductor wafers includes a scanning electron microscope (SEM) which obtains the composition ratios of each element of a plurality of foreign matter adhered to semiconductor wafers. A foreign matter plotting section is provided to obtain the distribution of the composition ratios of the plurality of foreign matter on the basis of a result obtained by the SEM. A foreign matter classifying process section classifies the plurality of foreign matter on the basis of the distribution. A foreign matter identifying process section compares the foreign matter classification result with data stored in advance in a foreign matter data base, thereby identifying the foreign matter type.