The Role of Stress on the Shape of the Amorphous-Crystalline Interface and Mask-Edge Defect Formation in Ion-Implanted Silicon

Abstract

ABSTRACTStress is known to affect the regrowth velocities during recrystallization of an amorphous layer. This study investigates how the stress from patterned structures alters regrowth and in turn affects defect formation. Prior to patterning, 80Å SiO2 and 1540Å of silicon nitride were deposited on a 200 mm [001] silicon wafer. A 40keV Si+ amorphizing implant at a dose of 1×1015 atoms/cm2 was then performed into the patterned wafer. The regrowth of the amorphous layer along the mask edge was studied by partially recrystallizing the layer for various times at 550°C both with the mask present and after etching off the oxide and nitride pads. A significant number of cross-sectional Transmission Electron Microscopy (TEM) samples were prepared and imaged. It was found that the stress from the patterned structures enhances the vertical and lateral regrowth velocities, as well as alters the shape of the amorphous-crystalline interface during regrowth. Previous studies have shown that uniaxial tensile stress increases the regrowth velocity. Simulations show that the region of interest in these samples is under tensile stresses, suggesting that this type of stress should accelerate the regrowth velocity. In addition dislocation half loops are observed to form along the mask edge for certain structures. The nucleation of these defects is suppressed by the presence of the film. The relationship between the stress from the patterned structures, the regrowth of the amorphous layer, and the formation of dislocation half-loops along the mask edge will be discussed.