Papers by Keyword: Large Area Substrates

Abstract: This paper addresses the limitations of current hot embossing machines for mass production applications. It describes the features of a hot embossing machine in terms of machine design for handling large surfaces, embossing head for fast and precise temperature control, and the alignment mechanism for controlling the residual uniformity and planar offsets for producing microstructures uniformly on large area by means of step-and-repeat method. The developed machine demonstrated that microstructures of features size of up to 100µm could be replicated in 250s on PMMA sheet with an electroplated nickel stamp. The linear dimensions of the embossed features however were generally smaller than those in the stamp, which highlighted the importance of precision process control.

Abstract: Growth of 3C-SiC films on an off-axis (111) Si substrate, with a miscut of 4° towards the <110> direction, is here reported. An extensive material characterization has been conducted by means of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Raman spectroscopy, indicating a very promising film quality with extremely flat surface and interface. Notwithstanding the excellent film quality, the wafer bow is still limiting its full employment in device realization.

Abstract: In-grown type stacking faults (SFs) like structures were observed in 100mm diameter 4H-SiC crystals by Photoluminescence (PL) mappings, and structural analyses using HRTEM clarified that the SF-like structures were comprised of 6H (3, 3) stacking sequences. The stacking sequences of the SF-like structures observed are different from the SFs formed in the a-face grown crystals, suggesting that it is due to 6H nucleation on {0001} plane terraces.

Abstract: One of the most crucial defects for the device fabrication on silicon carbide (SiC) substrates are areas with low crystalline quality and micro-pipe clusters which can still occupy several percent of the area in commercial available 4H-substrates. These defects originate from the seed or are generated by modification changes during growth and can be easily detected under crossed polarizers. In this presentation the historic development at SiCrystal from Acheson material to wafers with 100mm diameter, state of the art micro-pipe density and excellent crystalline quality (FWHM < 20 arcsec) on whole area will be shown. Additionally the influence of carbon inclusions on surface quality and the present dislocation densities in 4H substrates will be discussed. While carbon inclusions were reduced to uncritical levels dislocation densities are still in the range of 104 cm-2. Therefore strategies for further reduction will be pointed out. Finally a resistivity limit (16 mΩcm) for stacking fault formation during annealing at 1150°C will be defined.