Diffused resistive memory cell with buried active zone

• US 10,069,068 B2
• Filed: 05/03/2016
• Issued: 09/04/2018
• Est. Priority Date: 05/03/2016
• Status: Active Grant

• Current Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Bedau, Daniel
• Primary Examiner(s): Gebremariam, Samuel
• Application Number:
  US15/145,648
• Publication Number:
  US 20170324033A1
• Time in Patent Office: 854 Days
• CPC Class Codes: G11C 13/0002 using resistive RAM [RRAM] elements
• CPC Class Codes: G11C 13/0007 comprising metal oxide memory material, e.g. perovskites
• CPC Class Codes: G11C 2213/31 Material having complex metal oxide, e.g. perovskite structure
• CPC Class Codes: G11C 2213/32 Material having simple binary metal oxide structure
• CPC Class Codes: H10N 70/041 Modification of switching materials after formation, e.g. doping shaping H10N70/061
• CPC Class Codes: H10N 70/043 by implantation
• CPC Class Codes: H10N 70/20 Multistable switching devices, e.g. memristors
• CPC Class Codes: H10N 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/8833 Binary metal oxides, e.g. TaOx
• CPC Class Codes: H10N 70/8836 Complex metal oxides, e.g. perovskites, spinels

Abstract

An apparatus for non-volatile memory, and more specifically a ReRAM device with a buried resistive memory cell. The memory cell includes a first contact disposed on a substrate, an active layer, a second contact, a first diffused zone disposed within the active layer, a second diffused zone disposed within the active layer, and an active switching zone disposed within the active layer in between the first diffused zone and the second diffused zone. In one embodiment, the active zone may be doped by diffusion or ion implantation and/or may be fabricated utilizing a self-aligned process. In another embodiment, the memory cell may combine a deep implant and shallow diffusion well to create the active zone. The vertically and laterally isolated buried resistive memory cell concentrates the electric field away from the edges of the device and eliminates the effects of interface impurities and contaminants.

Claims

1. A ReRAM device, comprising:

a first contact;

a second contact; and

an active layer disposed between the first contact and the second contact, wherein the active layer comprises;

a diffused zone adjacent the first contact, wherein the diffused zone has a first composition; and

an active zone disposed between the diffused zone and the second contact, wherein the active zone has a second composition different from the first composition of the diffused zone, wherein the diffused zone is placed within the active layer and wherein the diffused zone has at least one side and one bottom surface contacting the active layer.

2. The device of claim 1, wherein the active zone comprises a binary or complex metal oxide material selected from the group consisting of tantalum oxide, hafnium oxide, titanium oxide, zirconium dioxide, aluminum oxide, titanium dioxide, zinc oxide, manganates, cuprates, or nickelates.

3. The device of claim 2, wherein the diffused zone comprises a metal or metal alloy selected from the group consisting of aluminum, tantalum, indium, tin, silver, copper, germanium, or hafnium.

4. The device of claim 1, wherein the diffused zone comprises a metal or metal alloy selected from the group consisting of aluminum, tantalum, indium, tin, silver, copper, germanium or hafnium.

5. The device of claim 1, wherein the active layer that has a gradient that changes from the first contact to the second contact.

6. The device of claim 5, wherein the gradient is an oxygen gradient.

7. A ReRAM device, comprising:

a first contact;

a second contact; and

an active layer disposed between the first contact and the second contact, wherein the active layer has an oxygen gradient, wherein the active layer comprises;

a diffused zone adjacent the first contact, wherein the diffused zone has a first composition; and

an active zone disposed between the diffused zone and the second contact, wherein the active zone has a second composition different from the first composition of the diffused zone wherein the gradient is created by a dopant selected from the group consisting of indium or silicon.