Monolayer-by-monolayer growth of MgO layers using mg sublimation and oxidation

Patent metadata

Field	Value
Publication number	US-11597993-B2
Application number	US-202117316202-A
Country	US
Kind code	B2
Filing date	May 10, 2021
Priority date	Oct 16, 2018
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

A MgO layer is formed using a process flow wherein a Mg layer is deposited at a temperature <200° C. on a substrate, and then an anneal between 200° C. and 900° C., and preferably from 200° C. and 400° C., is performed so that a Mg vapor pressure >10 −6 Torr is reached and a substantial portion of the Mg layer sublimes and leaves a Mg monolayer. After an oxidation between −223° C. and 900° C., a MgO monolayer is produced where the Mg:O ratio is exactly 1:1 thereby avoiding underoxidized or overoxidized states associated with film defects. The process flow may be repeated one or more times to yield a desired thickness and resistance×area value when the MgO is a tunnel barrier or Hk enhancing layer. Moreover, a doping element (M) may be added during Mg deposition to modify the conductivity and band structure in the resulting MgMO layer.

First claim

What is claimed is:

1. A method comprising:
forming a first Mg monolayer by performing a first anneal at a first temperature on a first Mg layer; and
performing a first oxidation on the first Mg monolayer at a second temperature thereby forming a first MgO monolayer.

2. The method of claim 1 , wherein all Mg atoms in the first MgO monolayer are oxidized.

3. The method of claim 1 , wherein the first MgO monolayer is a tunnel barrier layer in a magnetic tunnel junction device.

4. The method of claim 1 , wherein the first MgO monolayer is an Hk enhancing layer in a magnetic tunnel junction device.

5. The method of claim 1 , wherein the performing of the first anneal at the first temperature on the first Mg layer results in a Mg vapor pressure of at least 10 −6 Torr.

6. The method of claim 1 , further comprising:
forming a reference layer, and
forming the first Mg layer on the reference layer.

7. The method of claim 1 , further comprising:
forming a second Mg monolayer on the first MgO monolayer; and
performing a second oxidation on the second Mg monolayer thereby forming a second MgO monolayer.

8. The method of claim 1 , wherein the first temperature ranges from about 200° C. to about 900° C., and
wherein the second temperature from about −223° C. to about 900° C.

9. A method comprising:
forming a first doped Mg-containing layer;
treating the first doped Mg-containing layer to form a first doped Mg-containing monolayer; and
oxidizing the first doped Mg-containing monolayer to form a first oxidized doped Mg-containing monolayer.

10. The method of claim 9 , wherein the treating of the first doped Mg-containing layer to form the first doped Mg-containing monolayer includes performing an anneal process at a temperature ranging from about 200° C. to about 900° C.

11. The method of claim 9 , wherein the first doped Mg-containing layer includes a dopant selected from the group consisting of Ti, V, Cr, Mn, Fe, Ga, In, Al, Si, Ge, Sn, Zr, Mo, Nb, Hf, Ta, W and N.

12. The method of claim 9 , further comprising:
forming a second doped Mg-containing layer on the first oxidized doped Mg-containing monolayer;
treating the second doped Mg-containing layer to form a second doped Mg-containing monolayer; and
oxidizing the second doped Mg-containing monolayer to form a second oxidized doped Mg-containing monolayer.

13. The method of claim 12 , further comprising:
forming a free layer on the second oxidized doped Mg-containing monolayer; and
forming an Hk enhancing layer on the free layer.

14. The method of claim 12 , further comprising forming a reference layer on the second oxidized doped Mg-containing monolayer.

15. The method of claim 9 , wherein the treating of the first doped Mg-containing layer to form the first doped Mg-containing monolayer includes performing a first anneal process at a first temperature, and
wherein the oxidizing of the first doped Mg-containing monolayer to form the first oxidized doped Mg-containing monolayer includes performing a second anneal process at a second temperature that is different than the first temperature.

16. A method of forming a magnetic tunnel junction device, the method comprising:
forming a first metal layer on a substrate;
performing an evaporation process on the first metal layer to remove a portion of metal atoms to thereby form a metal monolayer; and
oxidizing the metal monolayer to form an oxidized monolayer, wherein all metal atoms in the oxidized monolayer are oxidized.

17. The method of claim 16 , wherein the first metal layer includes Mg atoms.

18. The method of claim 16 , wherein the performing of the evaporation process occurs at a first temperature, and
wherein the oxidizing of the metal monolayer occurs at a second temperature that is different than the first temperature.

19. The method of claim 16 , wherein the first metal layer includes a dopant having a higher melting point than the metal atoms of the metal layer.

20. The method of claim 19 , wherein the dopant is selected from the group consisting of Ti, V, Cr, Mn, Fe, Ga, In, Al, Si, Ge, Sn, Zr, Mo, Nb, Hf, Ta, W and N, and
wherein the monolayer and the oxidized monolayer include the doping element.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Patel Sahil
• Jan Guenole
• Wang Yu-Jen

Classifications

• H10P95/90

  Thermal treatments, e.g. annealing or sintering · CPC title

• H01F41/307

  insulating or semiconductive spacer · CPC title

• C23C14/5873

  Removal of material · CPC title

• C23C14/5853

  Oxidation · CPC title

• C23C14/5806

  Thermal treatment · CPC title