# US 8,772,753 B2 · Nonvolatile semiconductor storage device

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- Number: US 8,772,753 B2
- Document ID: US8772753B2
- Status: Granted
- Kind: B2
- Application number: 13/596,395
- Filed: 2012-08-28
- Published: 2013-09-12
- Granted: 2014-07-08
- Earliest claimed: 2012-03-07
- Assignees: Kabushiki Kaisha Toshiba
- Applicants: Masanobu Baba
- Inventors: Masanobu Baba
- Web page: https://patentgrep.com/patent/US8772753B2

## CPC

- H10N 70/245: {the species being metal cations, e.g. programmable metallization cells}
- H10B 63/80: {Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays}
- H10N 70/063: {by etching of pre-deposited switching material layers, e.g. lithography}
- H10N 70/8416: {adapted for supplying ionic species}
- H10N 70/8833: {Binary metal oxides, e.g. TaOx}
- H10N 70/884: {based on at least one element of group IIIA, IVA or VA, e.g. elemental or compound semiconductors (compounds of sulfur, selenium or tellurium, e.g. chalcogenides H10N70/882; oxides or nitrides H10N70/883)}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B: ELECTRONIC MEMORY DEVICES

## Abstract

A nonvolatile semiconductor storage device includes a word line, a first electrode, a high resistance ion diffusion layer, a second electrode, and a bit line. The word line is made of a conductive material extending in a first direction. The first electrode is provided on the word line. The high resistance ion diffusion layer is provided on the first electrode. The second electrode is provided on the ion diffusion layer and configured to supply a metal into the ion diffusion layer upon application of a positive voltage relative to the first electrode. The bit line is provided on the second electrode and made of a conductive material extending in a second direction orthogonal to the first direction. The ion diffusion layer contains oxygen at a higher concentration on the word line side than on the bit line side.

## Claims

### Claim 1

A nonvolatile semiconductor storage device comprising:
a word line made of a conductive material extending in a first direction;
a first electrode provided on the word line and electrically connected to the word line;
a high resistance ion diffusion layer provided on the first electrode on opposite side from the word line and electrically connected to the first electrode, the ion diffusion layer including a high oxygen concentration region and a low oxygen concentration region, the high oxygen concentration region being in contact with the first electrode, the low oxygen concentration region being provided on the high oxygen concentration region, the low oxygen concentration region being in contact with the high oxygen concentration region, the high oxygen concentration region having a higher oxygen concentration than the low oxygen concentration region;
a second electrode provided on the ion diffusion layer on opposite side from the word line, the second electrode being in contact with the low oxygen concentration region, the second electrode being configured to supply a metal into the low oxygen concentration region upon application of a positive voltage relative to the first electrode; and
a bit line provided on the second electrode on opposite side from the word line, electrically connected to the second electrode, and made of a conductive material extending in a second direction orthogonal to the first direction,
the second electrode including the metal supplied into the low oxygen concentration region.

### Claim 2 (depends on 1)

The device according to claim 1, wherein average oxygen concentration of the high oxygen concentration region is higher than average oxygen concentration of the low oxygen concentration region.

### Claim 3 (depends on 1)

The device according to claim 1, wherein the low oxygen concentration region is formed so as not to contain oxygen, and the high oxygen concentration region is formed so as to contain oxygen.

### Claim 4 (depends on 1)

The device according to claim 1, wherein the high oxygen concentration region has an oxygen concentration of 1×1020/cm3 or more in its entire region.

### Claim 5 (depends on 1)

The device according to claim 1, wherein the ion diffusion layer is composed of Si.

### Claim 6 (depends on 5)

The device according to claim 5, wherein the ion diffusion layer is composed of amorphous silicon.

### Claim 7 (depends on 1)

The device according to claim 1, wherein the ion diffusion layer is composed of one of SiN, SiOx, SiNOx, TiOx, CoOx, NiOx, CuOx, MoOx, and HfOx.

### Claim 8 (depends on 1)

The device according to claim 1, wherein the second electrode is composed of one of Ag, Cu, Al, Co, Ni, and Ti.

### Claim 9 (depends on 1)

The device according to claim 1, wherein the first electrode is composed of n-type conductive polysilicon.

### Claim 10 (depends on 1)

The device according to claim 1, wherein the first electrode is composed of p-type conductive polysilicon.

### Claim 11 (depends on 1)

The device according to claim 1, wherein the first electrode is composed of one of TIN, Mo, and Ta.

### Claim 12 (depends on 1)

The device according to claim 1, wherein in the ion diffusion layer, oxygen concentration monotonically increases from the bit line side toward the word line side.