This study presents investigations about the physical mechanisms, origin, and methods to control the pattern dependency in selective epitaxial growth of Si1−xGex (x=0.14–0.32) layers. It is shown with a comprehensive experimental study that the local Si coverage of individual chips on patterned wafers is the main parameter for the layer profile in the epitaxial growth. This was explained by the gas depletion of the growth species in the low velocity boundary layer over the wafer. The gas depletion radius around each oxide opening was in the centimeter range which is related to the boundary layer thickness. The results from these experiments were applied to grow Si0.75Ge0.25 layers with B concentration of 4×1020cm−3 selectively for elevated source and drains in fully depleted ultrathin body silicon on insulator p metal oxide semiconductor field effect transistor (p-MOSFET) devices. The epitaxy control was maintained over a wide range of device sizes by optimized process parameters in combination with a wafer pattern design consisting of dummy features causing a uniform gas depletion over the chips on the wafer.

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Abstract-The influence of chip layout and architecture on the pattern dependency of selective epitaxy of B-doped SiGe layers has been studied. The variations of Ge-, B-content, and growth rate have been investigated locally within a wafer and globally from wafer to wafer. The results are described by the gas depletion theory. Methods to control the variation of layer profile are suggested.Index Terms-Loading effect, pattern dependency, selective epitaxy, SiGe.

The application of high-resolution x-ray diffraction for detecting and distinguishing defects in SiGe(C) layers is presented. A depth profile of the defects in SiGe/Si multilayers has been performed by using high-resolution reciprocal lattice mapping at different asymmetric reflections. Transmission electron microscopy was also applied in order to observe defects in the layers and these results were linked with the x-ray analysis. The substitutional C or B concentration in SiGe was measured by the shift of layer peak compared to the intrinsic layers. The thermal stability of the SiGe layers was investigated in order to rank the epitaxial quality of the SiGe below the detection limit of x-ray technique. It has also been demonstrated that x-ray analysis can be used for in-line process monitoring of layers grown in small device openings on patterned substrates. These types of analysis have also been used routinely for the evaluation of processed samples.

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