Development of Analysis Technology for Nanometer Ultra-Shallow Junctions

Ultra-shallow junction technology has been developed with the progress of nanometer semiconductor devices. Ultra-shallow junctions must be able to reduce the short channel effects and the sheet resistance in the source/drain regions so that the device performance can be improved. However, high-concentration impurities and defects introduced by ion implantation react with each other during junction formation. Hence, the physical mechanisms of dopant diffusion and activation become very complex near the surface in ultra-shallow junctions. New analysis techniques need to be developed in order to reveal these mechanisms. This project will analyze the dopant and carrier concentration near the surface using X-ray photoelectron spectroscopy and Hall measurement, respectively. The thickness of native oxide is quantitatively determined by X-ray photoelectron spectroscopy. The native oxide is removed and then another layer of native oxide is grown on the silicon substrate. The procedure removes surface silicon atoms layer by layer and each layer with a thickness resolution around one nanometer. Within each etching and regrowth period, dopant concentration is measured by X-ray photoelectron spectroscopy and carrier concentration is monitored by Hall measurement. The dependence of growth rate on dopant concentration will also be investigated in order to optimize the regrowth process. We will compare the measurement results with the data obtained from secondary ion mass spectroscopy, in order to convert the measurement data to real dopant profiles. The project will reveal the diffusion and activation mechanisms of high-concentration dopants near the surface during formation of ultra-shallow junctions. The results also help the optimization of ultra-shallow junction technology and the design of transistors.

Project ID:PB10007-2316
External Project ID:NSC100-2221-E182-010