Abstract: A semiconductor wafer with a test key structure is provided. The semiconductor wafer includes a semiconductor substrate including a scribe line region, a chip region, and a seal ring region between the scribe line region and the chip region. A test pad structure and a test element are disposed over the semiconductor substrate corresponding to the scribe line region. A conductive line is disposed over the semiconductor substrate corresponding to the seal ring region, and has two ends extending to the scribe line region and electrically connected between the test pad structure and the test element.

Abstract: Provided is a memory device including a substrate, a source region, a drain region, a source contact, a drain contact, at least two stack gates, and at least two selection gates. The source region and the drain region are both located in the substrate. The source contact is located on the source region and the drain contact is located on the drain region. A bottom area of the drain contact is greater than a bottom area of the source contact. The stack gates are located on the substrate at two sides of the source region respectively. The selection gates are located on the substrate at two sides of the drain region respectively. A distance between the selection gates located at two sides of the drain region is greater than a distance between the stack gates located at two sides of the source region.

Abstract: Provided is a memory device including a substrate, a source region, a drain region, a source contact, a drain contact, at least two stack gates, and at least two selection gates. The source region and the drain region are both located in the substrate. The source contact is located on the source region and the drain contact is located on the drain region. A bottom area of the drain contact is greater than a bottom area of the source contact. The stack gates are located on the substrate at two sides of the source region respectively. The selection gates are located on the substrate at two sides of the drain region respectively. A distance between the selection gates located at two sides of the drain region is greater than a distance between the stack gates located at two sides of the source region.

Abstract: Provided is a memory device including a substrate and a gate structure. The gate structure is located on the substrate. The gate structure includes a stack gate and a selection gate aside the stack structure. A topmost surface of the selection gate is lower than a topmost surface of the stack gate.

Abstract: Provided is a memory device including a substrate and a gate structure. The gate structure is located on the substrate. The gate structure includes a stack gate and a selection gate aside the stack structure. A topmost surface of the selection gate is lower than a topmost surface of the stack gate.