US 12,283,296 B2
Spin-transfer torque magnetoresistive memory device with a free layer stack including multiple spacers and methods of making the same
Tiffany Santos, San Jose, CA (US); and Neil Smith, San Jose, CA (US)
Assigned to Sandisk Technologies, Inc., Milpitas, CA (US)
Filed by SANDISK TECHNOLOGIES, INC., Milpitas, CA (US)
Filed on Jan. 14, 2022, as Appl. No. 17/575,840.
Application 17/575,840 is a continuation of application No. PCT/US2020/025183, filed on Mar. 27, 2020.
Application PCT/US2020/025183 is a continuation of application No. 16/558,552, filed on Sep. 3, 2019, granted, now 11,031,058.
Prior Publication US 2022/0139435 A1, May 5, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. G11C 11/16 (2006.01); H01F 10/32 (2006.01); H01F 41/32 (2006.01); H10B 61/00 (2023.01); H10N 50/01 (2023.01); H10N 50/80 (2023.01); H10N 50/85 (2023.01)
CPC G11C 11/161 (2013.01) [H01F 10/3259 (2013.01); H01F 10/3286 (2013.01); H01F 10/329 (2013.01); H01F 41/32 (2013.01); H10B 61/00 (2023.02); H10N 50/01 (2023.02); H10N 50/80 (2023.02); H10N 50/85 (2023.02)] 4 Claims
OG exemplary drawing
 
1. A method of forming a spin-transfer torque (STT) magnetoresistive memory device, comprising:
forming a reference layer having a fixed magnetization direction;
forming a nonmagnetic tunnel barrier layer over the reference layer; and
forming a free layer stack on the non-magnetic tunnel barrier layer by sequentially forming a proximal ferromagnetic layer, an intermediate ferromagnetic layer, a magnesium layer on a top surface of the intermediate ferromagnetic layer, a non-magnetic metal sub-monolayer having a thickness in a range from 0.1 Angstrom to 0.3 Angstrom and comprising tungsten, and a distal ferromagnetic layer;
wherein the proximal ferromagnetic layer comprises a proximal CoFeB layer, the intermediate ferromagnetic layer comprises an intermediate CoFe layer, and the distal ferromagnetic layer comprises a distal CoFe layer; and
wherein the magnesium layer is removed during formation of the non-magnetic metal sub-monolayer by atoms of the tungsten impinging on the magnesium layer.