Abstract: An optical inspection tool used to detect surface defects of a substrate include a chuck for holding a substrate and a lens unit disposed over the chuck. The lens unit includes at least a pair of oblique beam paths therein, wherein light penetrating the beam paths travels without angular deflection. The beam paths take the form of spaces formed through the lens unit, or flat portions formed on a lens within the lens unit. A camera is installed on the lens unit, and the camera converts light passing through the lens unit into an image. Methods of detecting surface defects of the substrate using the inspection tool are also provided.

Abstract: A phase-change random access memory device includes a global bit line connected to a write circuit and a read circuit; a plurality of local bit lines, each of which being connected to a plurality of phase-change memory cells; and a plurality of column select transistors selectively connecting the global bit line with each of the plurality of local bit lines. Each column select transistor has a resistance that depends on distance from the write circuit and the read circuit.

Abstract: A phase-change random access memory device includes a global bit line connected to a write circuit and a read circuit; a plurality of local bit lines, each of which being connected to a plurality of phase-change memory cells; and a plurality of column select transistors selectively connecting the global bit line with each of the plurality of local bit lines. Each column select transistor has a resistance that depends on distance from the write circuit and the read circuit.

Abstract: An optical inspection tool used to detect surface defects of a substrate include a chuck for holding a substrate and a lens unit disposed over the chuck. The lens unit includes at least a pair of oblique beam paths therein, wherein light penetrating the beam paths travels without angular deflection. The beam paths take the form of spaces formed through the lens unit, or flat portions formed on a lens within the lens unit. A camera is installed on the lens unit, and the camera converts light passing through the lens unit into an image. Methods of detecting surface defects of the substrate using the inspection tool are also provided.