# US 12,002,524 B2 · Sequential wordline erase verify schemes

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,002,524 B2
- Document ID: US12002524B2
- Status: Granted
- Kind: B2
- Application number: 18/085,783
- Filed: 2022-12-21
- Published: 2023-04-20
- Granted: 2024-06-04
- Earliest claimed: 2021-06-01
- Assignees: Micron Technology, Inc.
- Applicants: Micron Technology, Inc.
- Inventors: Ronit Roneel Prakash; Jiun-Horng Lai; Chengkuan Yin; Shinji Sato
- Web page: https://patentgrep.com/patent/US12002524B2

## CPC

- G11C 16/3445: {Circuits or methods to verify correct erasure of nonvolatile memory cells}
- G11C 16/0483: {comprising cells having several storage transistors connected in series}
- G11C: STATIC STORES (semiconductor memory devices H10B)

## Abstract

A memory device includes a memory array including a plurality of wordline groups, each wordline group of the plurality of wordline groups including a set of even wordlines and a set of odd wordlines, and control logic, operatively coupled with the memory array, to perform operations including identifying a set of failing wordline groups from the plurality of wordline groups, the set of failing wordline groups including at least one failing wordline group determined to have failed a first erase verify of an erase verify process, and causing a second erase verify of the erase verify process to be performed sequentially with respect to each failing wordline group of the set of failing wordline groups.

## Claims

### Claim 1

A memory device comprising:
a memory array comprising a plurality of wordline groups, wherein each wordline group of the plurality of wordline groups comprises a set of even wordlines and a set of odd wordlines; and
control logic, operatively coupled with the memory array, to perform operations comprising:
identifying, from the plurality of wordline groups, a set of passing wordline groups and a set of failing wordline groups, wherein the set of passing wordline groups comprises at least one passing wordline group determined to have passed a first erase verify of an erase verify process, and wherein the set of failing wordline groups comprises at least one failing wordline group determined to have failed the first erase verify;
causing an inhibiting bias voltage to be applied with respect to each passing wordline group of the set of passing wordline groups; and
causing a second erase verify of the erase verify process to be performed sequentially with respect to each failing wordline group of the set of failing wordline groups.

### Claim 2 (depends on 1)

The memory device of claim 1, wherein the operations further comprise causing the first erase verify to be performed sequentially with respect to each wordline group of the plurality of wordline groups by causing the first erase verify to be performed with respect to the set of even wordlines independently from the set of odd wordlines.

### Claim 3 (depends on 1)

The memory device of claim 1, wherein the operations further comprise:
causing a first erase pulse at a first erase bias voltage to be applied to a channel prior to performing the first erase verify; and
causing a second erase pulse at a second erase bias voltage greater than the first erase bias voltage to be applied to the channel prior to performing the second erase verify.

### Claim 4 (depends on 3)

The memory device of claim 3, wherein the inhibiting bias voltage is proportional to a difference between the second erase pulse and the first erase pulse.

### Claim 5 (depends on 4)

The memory device of claim 4, wherein the inhibiting bias voltage is equal to the difference between the second erase pulse and the first erase pulse plus an additional bias value.

### Claim 6 (depends on 1)

The memory device of claim 1, wherein the set of passing wordline groups comprises a passing wordline group with each wordline of the passing wordline group being associated with an erase threshold voltage value less than or equal to a target erase threshold voltage, and wherein the set of failing wordline groups comprises a failing wordline group with each wordline of the failing wordline group being associated with an erase threshold voltage greater than the target erase threshold voltage.

### Claim 7 (depends on 1)

The memory device of claim 1, wherein the operations further comprise:
determining that each failing wordline group of the set of failing wordline groups has passed the second erase verify; and
causing the erase verify process to terminate in response determining that each failing wordline group of the set of failing wordline groups has passed the second erase verify.

### Claim 8

A memory device comprising:
a memory array comprising a plurality of wordline groups, wherein each wordline group of the plurality of wordline groups comprises a set of even wordlines and a set of odd wordlines; and
control logic, operatively coupled with the memory array, to perform operations comprising:
causing an erase verify of an erase verify process to be performed sequentially with respect to each wordline group of the plurality of wordline groups;
determining whether each wordline group of the set of wordline groups has passed the erase verify; and
in response to determining that each wordline group has passed the erase verify, causing the erase verify process to terminate.

### Claim 9 (depends on 8)

The memory device of claim 8, wherein the operations further comprise: in response to determining that at least one wordline group of the set of wordline groups has failed the erase verify, causing a second erase verify of the erase verify process to be performed sequentially with respect to each failing wordline group of a set of failing wordline groups.

### Claim 10 (depends on 9)

The memory device of claim 9, wherein the operations further comprise:
causing a first erase pulse at a first erase bias voltage to be applied to a channel prior to causing the second erase verify to be performed; and
causing a second erase pulse at a second erase bias voltage greater than the first erase bias voltage to be applied to the channel prior to causing the second erase verify to be performed.

### Claim 11 (depends on 10)

The memory device of claim 10, wherein the operations further comprise: prior to causing the second erase verify to be performed, causing an inhibiting bias voltage to be applied with respect to each passing wordline group of a set of passing wordline groups identified after the erase verify, wherein the set of passing wordline groups comprises at least one passing wordline group of the plurality of wordline groups determined to have passed the first erase verify, and wherein the inhibiting bias voltage is proportional to a difference between the second erase pulse and the first erase pulse.

### Claim 12 (depends on 11)

The memory device of claim 11, wherein the inhibiting bias voltage is equal to the difference between the second erase pulse and the first erase pulse plus an additional bias value.

### Claim 13 (depends on 11)

The memory device of claim 11, wherein the set of passing wordline groups comprises a passing wordline group with each wordline of the passing wordline group being associated with an erase threshold voltage value less than or equal to a target erase threshold voltage, and wherein the set of failing wordline groups comprises a failing wordline group with each wordline of the failing wordline group being associated with an erase threshold voltage greater than the target erase threshold voltage.

### Claim 14

A method comprising:
identifying, by processing device from a plurality of wordline groups, a set of passing wordline groups and a set of failing wordline groups, wherein each wordline group of the plurality of wordline groups comprises a set of even wordlines and a set of odd wordlines, wherein the set of passing wordline groups comprises at least one passing wordline group determined to have passed a first erase verify of an erase verify process, and wherein the set of failing wordline groups comprises at least one failing wordline group determined to have failed the first erase verify;
causing, by the processing device, an inhibiting bias voltage to be applied with respect to each passing wordline group of the set of passing wordline groups; and
causing, by the processing device, a second erase verify of the erase verify process to be performed sequentially with respect to each failing wordline group of the set of failing wordline groups.

### Claim 15 (depends on 14)

The method of claim 14, further comprising causing, by the processing device, the first erase verify to be performed sequentially with respect to each wordline group of the plurality of wordline groups by causing the first erase verify to be performed with respect to the set of even wordlines independently from the set of odd wordlines.

### Claim 16 (depends on 14)

The method of claim 14, further comprising:
causing, by the processing device, a first erase pulse at a first erase bias voltage to be applied to a channel prior to performing the first erase verify; and
causing, by the processing device, a second erase pulse at a second erase bias voltage greater than the first erase bias voltage to be applied to the channel prior to performing the second erase verify.

### Claim 17 (depends on 16)

The method of claim 16, wherein the inhibiting bias voltage is proportional to a difference between the second erase pulse and the first erase pulse.

### Claim 18 (depends on 17)

The method of claim 17, wherein the inhibiting bias voltage is equal to the difference between the second erase pulse and the first erase pulse plus an additional bias value.

### Claim 19 (depends on 14)

The method of claim 14, wherein the set of passing wordline groups comprises a passing wordline group with each wordline of the passing wordline group being associated with an erase threshold voltage value less than or equal to a target erase threshold voltage, and wherein the set of failing wordline groups comprises a failing wordline group with each wordline of the failing wordline group being associated with an erase threshold voltage greater than the target erase threshold voltage.

### Claim 20 (depends on 14)

The method of claim 14, further comprising:
determining, by the processing device, that each failing wordline group of the set of failing wordline groups has passed the second erase verify; and
causing, by the processing device, the erase verify process to terminate in response determining that each failing wordline group of the set of failing wordline groups has passed the second erase verify.