Patent ID: 11972808
Assignee: SANDISK TECHNOLOGIES, INC.
Field: Computer technology (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 8:
9. The controller as set forth in claim 8, wherein the drain-side select gate transistor of the plurality of memory holes of each of the plurality of strings is configured to retain a transistor threshold voltage, the plurality of memory holes comprise memory cells connected to one of a plurality of word lines, the memory cells are each configured to retain a threshold voltage corresponding to one of a plurality of data states, the memory cells are connected in series between the drain-side select gate transistor and a source-side select gate transistor on a source-side of each of the plurality of memory holes, the plurality of word lines and a plurality of dielectric layers extend horizontally and overlay one another in an alternating fashion in a stack, the plurality of memory holes extend vertically through the stack, the drain-side select gate transistor of each of the plurality of memory holes is connected to one of a plurality of bit lines and the source-side select gate transistor of each of the plurality of memory holes is connected to a source line, the rows include full circle rows and semi-circle rows comprising the plurality of memory holes being partially cut by a slit half etch, and the controller is further configured to:
instruct the memory apparatus to check the transistor threshold voltage of the drain-side select gate transistor of at least one of the plurality of strings including semi-circle rows on a consistent basis;
determine whether the transistor threshold voltage of the drain-side select gate transistor of the at least one of the plurality of strings including semi-circle rows is less than a predetermined drain voltage threshold; and
determine the downshift recovery trigger event has occurred in response to the transistor threshold voltage of the drain-side select gate transistor of the at least one of the plurality of strings including semi-circle rows being less than the predetermined drain voltage threshold.