# US 2014/0154860 A1 · Memory Cells, Methods of Forming Memory Cells, and Methods of Programming Memory Cells

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- Number: US 2014/0154860 A1
- Document ID: US20140154860A1
- Status: Published application
- Kind: A1
- Application number: 14/173,096
- Filed: 2014-02-05
- Published: 2014-06-05
- Earliest claimed: 2011-02-24
- Assignees: Micron Technology, Inc.
- Applicants: Micron Technology, Inc.
- Inventors: Jun Liu; Gurtej S. Sandhu
- Web page: https://patentgrep.com/patent/US20140154860A1

## CPC

- G11C 13/0069: {Writing or programming circuits or methods}
- G11C 13/0007: {comprising metal oxide memory material, e.g. perovskites}
- H10B 63/20: {comprising selection components having two electrodes, e.g. diodes}
- H10N 70/021: {Formation of switching materials, e.g. deposition of layers}
- H10N 70/043: {by implantation}
- H10N 70/24: {based on migration or redistribution of ionic species, e.g. anions, vacancies}
- H10N 70/883: {Oxides or nitrides}
- G11C 2013/0073: {Write using bi-directional cell biasing}
- G11C 2213/72: Array wherein the access device being a diode
- G11C 2213/73: Array where access device function, e.g. diode function, being merged with memorizing function of memory element
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H10B: ELECTRONIC MEMORY DEVICES
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

Some embodiments include methods in which a memory cell is formed to have programmable material between first and second access lines, with the programmable material having two compositionally different regions. A concentration of ions and/or ion-vacancies may be altered in at least one of the regions to change a memory state of the memory cell and to simultaneously form a pn diode. Some embodiments include memory cells having programmable material with two compositionally different regions, and having ions and/or ion-vacancies diffusible into at least one of the regions. The memory cell has a memory state in which the first and second regions are of opposite conductivity type relative to one another.

## Claims

### Claim at position 1

1-12. (canceled)

### Claim 13

A method of forming and programming a memory cell, comprising:
forming a programmable material to be between first and second access lines, the programmable material having two compositionally different regions; and
altering a concentration of ions and/or ion vacancies in at least one of the regions of the programmable memory material to change a memory state of the memory cell and to simultaneously form a pn diode within the programmable material.

### Claim 14 (depends on 13)

The method of claim 13 wherein:
said at least one of the first and second regions comprises a composition containing oxygen in combination with one or more of praseodymium, barium, calcium, manganese, strontium, titanium, iron, cesium and lead; and
the ions are oxygen-containing ions and/or the vacancies are vacancies of oxygen-containing ions.

### Claim 15 (depends on 13)

The method of claim 13 wherein the memory cell has two memory states, with one of the memory states having the pn diode within the memory cell in a first orientation within the first and second regions, and with the other of the memory states having a pn diode within the first and second regions in an opposite orientation to the first orientation.

### Claim 16 (depends on 13)

The method of claim 13 wherein the memory cell has two memory states, with one of the memory states having the pn diode within the memory cell, and with the other of the memory states having one of the regions as an electrically insulative material.

### Claim 17 (depends on 13)

The method of claim 13 wherein the concentration of ions and/or of the ion vacancies is altered in one of the regions, and wherein the other of the regions is a conductively-doped semiconductor material.

### Claim 18 (depends on 13)

The method of claim 13 wherein at least one of the access lines is permeable to the ions and/or to the ion vacancies.

### Claim 19 (depends on 13)

The method of claim 13 wherein neither of the access lines is permeable to the ions and/or to the ion vacancies.

### Claim at position 9

20-30. (canceled)

### Claim 31

A method of forming and programming a memory cell, comprising:
forming a first region of a programmable material over and directly against a first access line;
forming a second region of the programmable material over the first region; the first and second regions being compositionally different from one another;
forming a second access line over and directly against the second region;
wherein the programmable material has two distinguishable and interchangeable memory states, with one of the states being a “SET” state and the other being a “RESET” state; the “SET” state passing greater current than the “RESET” state when an electrical field is applied across the programmable material; the “SET” and “RESET” states being interchanged with one another by altering one or both of a concentration of ions and a concentration of ion vacancies in at least one of the first and second regions;
wherein the first region is of a first conductivity type in the “SET” state and the second region is of a second conductivity type in the “SET” state, with the second conductivity type being opposite of the first conductivity type; the first and second regions together comprising a pn diode in the programmable material in the “SET” state; and
altering the ion concentration and/or the ion vacancy concentration in said at least one of the first and second regions to change the programmable material from one memory state to the other.

### Claim 32 (depends on 31)

The method of claim 31 wherein the conductive-type state of the first region is n-type in the “SET” state and the conductivity type of the second region is p-type in the “SET” state.

### Claim 33 (depends on 31)

The method of claim 31 wherein the conductive-type state of the first region is p-type in the “SET” state and the conductivity type of the second region is n-type in the “SET” state.

### Claim 34 (depends on 31)

The method of claim 31 one of the first and second regions comprises conductively-doped semiconductor material and remains the same conductivity type in both the “SET” and “RESET” states.

### Claim 35

A method of forming and programming a memory cell, comprising:
forming a first region of a programmable material over and directly against a first access line;
forming a second region of the programmable material over the first region;
forming a second access line over and directly against the second region;
wherein the programmable material has two distinguishable and interchangeable memory states, with one of the memory states being a “SET” state and the other being a “RESET” state; the “SET” state passing greater current than the “RESET” state when an electrical field is applied across the programmable material; the “SET” and “RESET” states being interchanged with one another by altering one or both of a concentration of ions and a concentration of ion vacancies in the second region to reversibly form a filament across the second region;
wherein the first region is of a first conductivity type in the “SET” state and the filament is of a second conductivity type in the “SET” state, with the second conductivity type being opposite of the first conductivity type; the first and second regions together comprising a pn diode in the programmable material in the “SET” state; and
altering the ion concentration and/or the ion vacancy concentration in the second region to change the programmable material from one memory state to the other.

### Claim 36

A method of forming and programming a memory cell, comprising:
forming a programmable material over a first access line; the programmable material having a first region and a second region;
forming a second access line over the programmable material;
wherein the programmable material has two distinguishable and interchangeable memory states, with one of the memory states being a “SET” state and the other being a “RESET” state; the “SET” state passing greater current than the “RESET” state when an electrical field is applied across the programmable material; the “SET” and “RESET” states being interchanged with one another by modifying one or both of a concentration of ions and a concentration of ion vacancies in the second region to reversibly alter the second region;
wherein the first region is of a first conductivity type in the “SET” state and at least part of the second region is of a second conductivity type in the “SET” state, with the second conductivity type being opposite of the first conductivity type; the first and second regions together comprising a pn diode in the programmable material in the “SET” state; and
modifying the ion concentration and/or the ion vacancy concentration in the second region to change the programmable material from one memory state to the other.

### Claim 37 (depends on 13)

The method of claim 13 wherein the altering alters a concentration of oxygen-containing ions.

### Claim 38 (depends on 13)

The method of claim 13 wherein the altering alters an amount of vacancies of oxygen-containing ions.