Formation of high-performance PtSi/p-Si Schottky barrier detector using high-resolution transmission electron microscope

Abstract

The effects of the discontinuity in thin PtSi layers on the performance of PtSi/p-Schottky-barrier detectors (SBDs) have been studied in detail in this paper. We have observed discontinuous PtSi film formed in large detector size and continuous PtSi film formed in smaller detector size when very thin PtSi is formed at temperature of 350 degrees C or below. For the SBDs with discontinuous PtSi film, the quantum efficiency is lower and barrier height is higher compared to those with continuous PtSi films. However, if the PtSi layer thickness is larger than 4 nm, the PtSi islands in the layer coalesce and the performance of the detector is similar to that of SBDs with continuous PtSi film. The formation of discontinuous PtSi layer results from the 3D growth of PtSi at preferential steps. However, the smaller area for PtSi formation can promote the 2D growth. When the PtSi formation temperature is 450 degrees C or above, thin PtSi forms in islands either in larger size test-key or in smaller size pixel. The results studied by transmission electron microscopy indicate that PtSi layer formed above 450 degrees C is preferentially oriented to (100) Si substrate. This results in the 3D PtSi growth. 256 X 244 PtSi/p-Si arrays monolithically integrated to read- out circuit have been fabricated using standard Si IC processes. From the measurement of uniformity and noise equivalent temperature difference of arrays, the PtSi/p-Si Schottky-barrier detector is shown to be operated under background limited condition.