Multi-terminal cross-point synaptic device using nanocrystal dot structures

Patent metadata

Field	Value
Publication number	US-2020005129-A1
Application number	US-201816021824-A
Country	US
Kind code	A1
Filing date	Jun 28, 2018
Priority date	Jun 28, 2018
Publication date	Jan 2, 2020
Grant date	—

Abstract

Described herein is a crossbar array that includes a cross-point synaptic device at each of a plurality of crosspoints. The cross-point synaptic device includes a weight storage element comprising a set of nanocrystal dots. Further, the cross-point synaptic device includes at least three terminals for interacting with the weight storage element, wherein a weight is stored in the weight storage element by sending a first electric pulse via a gate terminal from the at least three terminals, the first electric pulse causes the nanocrystal dots to store a corresponding charge, and the weight is erased from the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse.

First claim

What is claimed is:

1 . A crossbar array comprising:
a cross-point synaptic device at each of a plurality of crosspoints, the cross-point synaptic device comprising:
a weight storage element comprising a set of nanocrystal dots; and
at least three terminals for interacting with the weight storage element, wherein a weight is stored in the weight storage element by sending a first electric pulse via a gate terminal from the at least three terminals, the first electric pulse causes the nanocrystal dots to store a corresponding charge, and the weight is erased from the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse.

2 . The crossbar array of claim 1 , wherein the nanocrystal dots have a uniform size, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

3 . The crossbar array of claim 1 , wherein the nanocrystal dots have an increasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

4 . The crossbar array of claim 1 , wherein the nanocrystal dots have a decreasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

5 . The crossbar array of claim 1 , wherein the nanocrystal dots have one of a round shape, a half-moon shape, and a square shape.

6 . The crossbar array of claim 1 , wherein the nanocrystal dots are in a single layer in the gate terminal.

7 . The crossbar array of claim 1 , wherein the nanocrystal dots are stacked in multiple layers in the gate terminal.

8 . A system comprising:
a controller; and a crossbar array coupled with the controller, the crossbar array configured to operate as a neural network, the crossbar array comprising:
a cross-point synaptic device at each of a plurality of crosspoints, the cross-point synaptic device comprising:
a weight storage element comprising a set of nanocrystal dots; and
at least three terminals for interacting with the weight storage element, wherein a weight is stored in the weight storage element by sending a first electric pulse via a gate terminal from the at least three terminals, the first electric pulse causes the nanocrystal dots to store a corresponding charge, and the weight is erased from the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse.

9 . The system of claim 8 , wherein the nanocrystal dots have a uniform size, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

10 . The system of claim 8 , wherein the nanocrystal dots have an increasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

11 . The system of claim 8 , wherein the nanocrystal dots have a decreasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

12 . The system of claim 8 , wherein the nanocrystal dots have one of a round shape, a half-moon shape, and a square shape.

13 . The system of claim 8 , wherein the nanocrystal dots are in a single layer in the gate terminal.

14 . The system of claim 8 , wherein the nanocrystal dots are stacked in multiple layers in the gate terminal.

15 . A method for controlling weight stored in a crossbar array used for implementing a neural network, the method comprising:
updating a weight stored by a weight storage element of a cross-point synaptic device at each of a plurality of crosspoints of the crossbar array by sending a first electric pulse via a gate terminal of the weight storage element, the first electric pulse causes a set of nanocrystal dots in the gate terminal to store a corresponding charge representing the weight; and erasing the weight stored in the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse.

16 . The method of claim 15 , wherein the nanocrystal dots have a uniform size, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

17 . The method of claim 15 , wherein the nanocrystal dots have an increasing size from a first terminal to a second terminal of the weight storage element, the size controlled by temperature when growing the nanocrystal dots in a dielectric material.

18 . The method of claim 15 , wherein the nanocrystal dots have one of a round shape, a half-moon shape, and a square shape.

19 . The method of claim 15 , wherein the nanocrystal dots are in a single layer in the gate terminal.

20 . The method of claim 15 , wherein the nanocrystal dots are stacked in multiple layers in the gate terminal.

Assignees

• IBM

Inventors

• Chan Kevin K
• Frank Martin M
• Han Jin Ping

Classifications

• G06N3/044

  Recurrent networks, e.g. Hopfield networks · CPC title

• G06N3/065 Primary

  Analogue means · CPC title

• G06N3/045

  Combinations of networks · CPC title

• G06N3/084 Primary

  Backpropagation, e.g. using gradient descent · CPC title

• G06N3/08

  Learning methods · CPC title