Patent ID: 8603891

Claim:
A method for forming a vertical memory device, the method comprising: forming a plurality of first trenches in a silicon substrate, the plurality of first trenches extending horizontally in a first direction in an array region of the vertical memory device; at least partially filling the plurality of first trenches with a polysilicon material; forming a plurality of second trenches in the array region and in a word line end region, the plurality of second trenches extending horizontally in a second direction perpendicular to the first direction, wherein forming each second trench of the plurality of second trenches comprises: removing one of a silicon material of the silicon substrate in the array region and an oxide material of the word line end region with a first material removal act to partially form the second trench; and removing the other of the silicon material of the silicon substrate in the array region and the oxide material of the word line end region with a second material removal act different than the first material removal act to complete the second trench.