3D Non-Volatile Memory With Control Gate Length Based On Memory Hole Diameter

摘要

A structure and fabrication process are provided for a 3D stacked non-volatile memory device which compensates for variations in a memory hole diameter. The memory hole diameter is smaller at the bottom of the stack, resulting in more severe read disturb. To compensate, the word line layers are thicker at the bottom of the stack and can increase gradually from the bottom to the top of the stack. As a result, the length of the control gates of the memory cells is greater at the bottom of the stack. The capacitance between the control gate and a charge trapping layer increased in proportion to the length of the control gates. During programming, a narrower threshold voltage (Vth) distribution is achieved for these memory cells. The Vth distributions can be placed closer together and downshifted to allow lowering of a read pass voltage in a subsequent sensing operation, reducing read disturb.

主权项

1. A non-volatile memory device, comprising:
a substrate; a plurality of memory cells formed above the substrate in multiple physical levels of memory cells in a three-dimensional non-volatile memory; a plurality of word line layers arranged alternatingly with dielectric layers in a stack, the plurality of memory cells are in communication with the plurality of word line layers; memory holes which extend through the stack, the memory holes have diameters which vary along the memory holes, a thickness of one word line layer of the plurality of word line layers is based on a position of the one word line layer in the stack, and the memory holes comprise columnar active areas of the plurality of memory cells; and circuitry in communication with the plurality of memory cells.