Fluorine doped non-volatile memory cells and methods for forming the same

Patent metadata

Field	Value
Publication number	US-10586705-B2
Application number	US-201815904041-A
Country	US
Kind code	B2
Filing date	Feb 23, 2018
Priority date	Nov 28, 2017
Publication date	Mar 10, 2020
Grant date	Mar 10, 2020

Abstract

A non-volatile memory cell is disclosed. In one example, the non-volatile memory cell includes: a substrate; a first oxide layer over the substrate; a floating gate over the first oxide layer; a second oxide layer over the floating gate; and a control gate at least partially over the second oxide layer. At least one of the first oxide layer and the second oxide layer comprises fluorine.

First claim

What is claimed is:

1. A non-volatile memory cell, comprising:
a substrate;
a first oxide layer over the substrate;
a floating gate over the first oxide layer;
a second oxide layer over the floating gate; and
a control gate at least partially over the second oxide layer, wherein the second oxide layer comprises fluorine ions that are doped into the second oxide layer through the control gate.

2. The non-volatile memory cell of claim 1 , wherein at least one of the floating gate and the control gate comprises polycrystalline silicon.

3. The non-volatile memory cell of claim 1 , further comprising an oxide-nitride-oxide (ONO) layer on the floating gate, wherein the ONO layer includes two oxide layers and a nitride layer between the two oxide layers.

4. The non-volatile memory cell of claim 3 , wherein the ONO layer is above the second oxide layer.

5. The non-volatile memory cell of claim 3 , wherein the ONO layer is below the second oxide layer.

6. The non-volatile memory cell of claim 1 , further comprising:
an additional floating gate over the first oxide layer; and
a common source diffusion region in the substrate between the floating gate and the additional floating gate.

7. The non-volatile memory cell of claim 1 , wherein the second oxide layer comprises at least one of the following fluorides: fluoroboron (BF x ); fluoronitrogen (NF x ); and fluorosilicon (SiF x ).

8. A method for forming a non-volatile memory cell, comprising:
forming a substrate;
forming a first oxide layer over the substrate;
forming a floating gate over the first oxide layer;
doping fluorine ions into the first oxide layer;
forming a second oxide layer over the floating gate;
forming a control gate; and
doping additional fluorine ions into the second oxide layer after the control gate is formed.

9. The method of claim 8 , wherein the fluorine ions are doped into the first oxide layer through the floating gate via ion implantation.

10. The method of claim 9 , wherein doping the fluorine ions into the first oxide layer further comprises:
forming a first ion mask above the floating gate to generate a masked pattern for the ion implantation.

11. The method of claim 8 , wherein the control gate is formed at least partially over the second oxide layer.

12. The method of claim 11 , wherein the additional fluorine ions are doped into the second oxide layer through the control gate via ion implantation.

13. The method of claim 12 , wherein doping the additional fluorine ions into the second oxide layer further comprises:
forming a second ion mask above the control gate to generate a masked pattern for the ion implantation.

14. The method of claim 11 , wherein at least one of the floating gate and the control gate comprises polycrystalline silicon.

15. The method of claim 8 , further comprising forming an oxide-nitride-oxide (ONO) layer on the floating gate, wherein the ONO layer includes two oxide layers and a nitride layer between the two oxide layers.

16. The method of claim 8 , further comprising:
forming an additional floating gate over the first oxide layer; and
forming a common source diffusion region in the substrate between the floating gate and the additional floating gate.

17. The method of claim 8 , wherein doping the fluorine ions comprises doping at least one of the following fluorides: fluoroboron (BF x ); fluoronitrogen (NF x ); and fluorosilicon (SiF x ).

18. The method of claim 8 , further comprising performing an annealing process to activate a silicon-fluorine bond in the first oxide layer based on at least one of: a furnace annealing and a rapid thermal anneal.

19. A method for forming a non-volatile memory cell, comprising:
forming a substrate;
forming a first oxide layer over the substrate;
forming a floating gate over the first oxide layer;
forming a second oxide layer over the floating gate;
forming a control gate at least partially over the second oxide layer; and
doping fluorine ions into the second oxide layer through the control gate.

20. The method of claim 19 , wherein the fluorine ions are doped into the second oxide layer through the control gate via ion implantation.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Chen Hung-Lin
• Lin Shiuan-Jeng
• Chiang Wen-Chih
• Chen Po-Ming
• Wang Tza-Hao

Classifications

• H10P30/22

  using masks · CPC title

• H10P32/20

  Diffusion for doping of insulating layers · CPC title

• H10P30/40 Primary

  into insulating materials · CPC title

• H10D64/01332

  Making the insulator · CPC title

• H10D64/0134 Primary

  with a treatment, e.g. annealing, after the formation of the insulator and before the formation of the conductor · CPC title