Erich Dr. Daub

Silicon crystals for future requirements of 300 mm wafers

Today, the main challenge in Si crystal growth development is the transition from 200 to 300 mm diameter. While the complexity of the growth process increases with larger charge size and crystal diameter, the perfection of the growth process must significantly improve to avoid any disturbances that result in structure loss during growth and, hence, cause massive material losses. With regard to the future bulk quality, radical changes may be required as the design rule approaches the size of the prevailing grown-in defect type. Therefore, grown-in defect free wafers will be required, which can be produced either directly by pulling, by wafer annealing or by epitaxy. As substrates for annealed and epitaxial wafers, nitrogen doped and fast pulled crystals provide sufficient internal gettering capability in low thermal budget device processes. Moreover, grown-in defects in nitrogen doped crystals are so small that they are easily covered during epitaxy or annealed during high temperature treatment.

Processing and Characterization of 300 mm Argon-Annealed Wafers

High nitrogen doped 300 mm silicon wafers annealed in 100 % argon ambient were investigated whether modified pulling conditions will lead to improved slip behavior and homogeneous radial oxygen precipitation. It turned out that increasing of the cooling rate during crystal pulling is beneficial on these wafer defect parameters. The void morphology was investigated by TEM and oxygen precipitation profiler measurements. Remarkably changes in the morphology of grown-in defects (voids) with varying the ingot cooling rate of these crystals can be observed.