SEMICONDUCTOR MEMORY SYSTEM INCLUDING SEMICONDUCTOR MEMORY DEVICE AND METHOD OF MANUFACTURING THE SAME

原文（中文）

A semiconductor memory system includes a semiconductor memory device. The semiconductor memory device includes a first stack, a second stack, and a third stack. The second stack is disposed over the first stack. The second stack includes a plurality of word lines stacked and insulated from each other. The third stack is disposed over the second stack. The third stack includes a second selection line. The channel structure includes a first channel pillar formed through the first stack and the second stack, and a second channel pillar contacting the first channel pillar and formed in the third stack. A diameter of the second channel pillar is smaller than a diameter of the first channel pillar.