# US 8,785,288 B2 · Methods of making memory cells

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- Number: US 8,785,288 B2
- Document ID: US8785288B2
- Status: Granted
- Kind: B2
- Application number: 14/024,836
- Filed: 2013-09-12
- Published: 2014-01-09
- Granted: 2014-07-22
- Earliest claimed: 2012-05-04
- Assignees: Micron Technology, Inc.
- Applicants: Micron Technology, Inc.
- Inventors: Gurtej S. Sandhu; Sumeet C. Pandey
- Web page: https://patentgrep.com/patent/US8785288B2

## CPC

- H10N 70/021: {Formation of switching materials, e.g. deposition of layers}
- H10N 70/20: Multistable switching devices, e.g. memristors
- H10N 70/231: {based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect}
- H10N 70/24: {based on migration or redistribution of ionic species, e.g. anions, vacancies}
- H10N 70/245: {the species being metal cations, e.g. programmable metallization cells}
- H10N 70/826: {adapted for essentially vertical current flow, e.g. sandwich or pillar type devices}
- H10N 70/841: {Electrodes}
- H10N 70/8822: {Sulfides, e.g. CuS}
- H10N 70/8825: {Selenides, e.g. GeSe}
- H10N 70/8828: {Tellurides, e.g. GeSbTe}
- H10N 70/8833: {Binary metal oxides, e.g. TaOx}
- H10N 70/8836: {Complex metal oxides, e.g. perovskites, spinels}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

Some embodiments include a memory cell having a data storage region between a pair of conductive structures. The data storage region is configured to support a transitory structure which alters resistance through the memory cell. The data storage region includes two or more portions, with one of the portions supporting a higher resistance segment of the transitory structure than another of the portions. Some embodiments include a method of forming a memory cell. First oxide and second oxide regions are formed between a pair of conductive structures. The oxide regions are configured to support a transitory structure which alters resistance through the memory cell. The oxide regions are different from one another so that one of the oxide regions supports a higher resistance segment of the transitory structure than the other.

## Claims

### Claim 1

A method of forming a memory cell, comprising:
forming a data storage region over a first conductive structure;
forming a second conductive structure over the data storage region;
wherein the data storage region is configured to support a transitory structure which alters resistance through the memory cell;
wherein the data storage region comprises two or more portions which are physically different from one another so that one of the portions supports a higher resistance segment of said transitory structure and another of the portions supports a lower resistance segment of said transitory structure; the physical difference being present prior to formation of the transitory structure;
wherein the memory cell is formed to have multiple portions of the data storage region which support multiple lower resistance segments of said transitory structure; and
wherein at least one of the lower resistance segments has a substantially different resistance than another of the lower resistance segments.

### Claim 2

A method of forming a memory cell, comprising:
forming a data storage region over a first conductive structure;
forming a second conductive structure over the data storage region;
wherein the data storage region is configured to support a transitory structure which alters resistance through the memory cell;
wherein the data storage region comprises two or more portions which are physically different from one another so that one of the portions supports a higher resistance segment of said transitory structure and another of the portions supports a lower resistance segment of said transitory structure; the physical difference being present prior to formation of the transitory structure;
wherein the memory cell is formed to have multiple portions of the data storage region which support multiple higher resistance segments of said transitory structure; and
wherein at least one of the higher resistance segments has a substantially different resistance than another of the higher resistance segments.

### Claim 3

A method of forming a memory cell, comprising:
depositing a first oxide region over a first conductive structure;
depositing a second oxide region over the first oxide region;
forming a second conductive structure over the second oxide region; the first and second oxide regions together being comprised by a data storage region configured to support a transitory structure which alters resistance through the memory cell;
wherein the first oxide region is different from an-e the second oxide region so that one of the oxide regions supports a higher resistance segment of said transitory structure than the other of the oxide regions; and
wherein the difference between the first and second oxide regions is a difference in crystallinity; and wherein said difference is imparted by:
depositing the first oxide region under first conditions utilizing a first temperature and a first pressure; and
depositing the second oxide region under second conditions utilizing a second temperature and a second pressure; with the second temperate being different from the first temperature and/or with the second pressure being different from the first pressure.

### Claim 4 (depends on 3)

The method of claim 3 wherein the transitory structure is a filament.

### Claim 5

A method of forming a memory cell, comprising:
depositing a first oxide region over a first conductive structure;
depositing a second oxide region over the first oxide region;
forming a second conductive structure over the second oxide region; the first and second oxide regions together being comprised by a data storage region configured to support a transitory structure which alters resistance through the memory cell;
wherein the first oxide region is different from the second oxide region so that one of the oxide regions supports a higher resistance segment of said transitory structure than the other of the oxide regions; and
wherein the difference between the first and second oxide regions is a difference in density; and wherein said difference is imparted by:
depositing the first oxide region under first conditions utilizing a first temperature and a first pressure; and
depositing the second oxide region under second conditions utilizing a second temperature and a second pressure; with the second temperate being different from the first temperature and/or with the second pressure being different from the first pressure.

### Claim 6

A method of forming a memory cell, comprising:
depositing a first oxide region over a first conductive structure;
depositing a second oxide region over the first oxide region;
forming a second conductive structure over the second oxide region; the first and second oxide regions together being comprised by a data storage region configured to support a transitory structure which alters resistance through the memory cell;
wherein the first oxide region is different from the second oxide region so that one of the oxide regions supports a higher resistance segment of said transitory structure than the other of the oxide regions;
wherein the difference between the first and second oxide regions is a difference in dopant concentration;
wherein the dopant is incorporated into one of the first and second oxide regions by in situ incorporation of the dopant into said one of the regions during the deposition of said one of the regions; and
wherein the dopant comprises one or more elements, other than oxygen, selected from the group consisting of group 16 of the periodic table.