Hybrid Metallic Hard Mask Stack for MTJ Etching

Patent metadata

Field	Value
Publication number	US-2016284985-A1
Application number	US-201514670596-A
Country	US
Kind code	A1
Filing date	Mar 27, 2015
Priority date	Mar 27, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

A hard mask stack for etching a magnetic tunneling junction (MTJ) structure is described. The hard mask stack is formed on a stack of MTJ layers on a bottom electrode and comprises an electrode layer on the MTJ stack, a buffer metal layer on the electrode layer, a metal hard mask layer on the buffer metal layer, and a dielectric layer on the metal hard mask layer wherein a dielectric mask is defined in the dielectric layer by a photoresist mask, a metal hard mask is defined in the metal hard mask layer by the dielectric mask, a buffer metal mask is defined in the buffer metal layer by the metal hard mask, an electrode mask is defined in the electrode layer by the buffer metal mask, and the MTJ structure is defined by the electrode mask wherein the electrode mask remaining acts as a top electrode.

First claim

What is claimed is:

1 . A hard mask stack for etching a magnetic tunneling junction (MTJ) structure comprising:
an electrode layer on a stack of MTJ layers on a bottom electrode; a buffer metal layer on said electrode layer; a metal hard mask layer on said buffer metal layer; and a dielectric layer on said metal hard mask layer wherein a dielectric mask is defined in said dielectric layer by a photoresist mask, a metal hard mask is defined in said metal hard mask layer by said dielectric mask, a buffer metal mask is defined in said buffer metal layer by said metal hard mask, an electrode mask is defined in said electrode layer by said buffer metal mask, and said MTJ structure is defined by said electrode mask wherein said electrode mask remaining after said MTJ structure is defined acts as a top electrode.

2 . The hard mask stack according to claim 1 wherein said electrode layer comprises Ta, TaN, Ti, or TiN having a thickness of between about 380 and 1000 Angstroms.

3 . The hard mask stack according to claim 1 wherein said buffer metal layer comprises PtMn, Ni, Cu, Mg, Ru, NiCr, NiFe, CoFeB, or CoFe alloy, having a thickness of between about 50 and 500 Angstroms.

4 . The hard mask stack according to claim 1 wherein said metal hard mask layer comprises Ta, TaN, Ti, or TiN and has a thickness of between about 50 and 300 Angstroms.

5 . The hard mask stack according to claim 1 wherein said dielectric layer comprises SiO 2 , SiN, or advanced patterning film having a thickness of between about 400 and 900 Angstroms.

6 . The hard mask stack according to claim 1 wherein said photoresist mask has a thickness of less than about 500 to 3600 Angstroms.

7 . A method for etching a magnetic tunneling junction (MTJ) structure comprising:
providing a stack of MTJ layers on a bottom electrode; depositing an electrode layer on said stack of MTJ layers; depositing a buffer metal layer on said electrode layer; depositing a metal hard mask layer on said buffer metal layer; depositing a dielectric layer on said metal hard mask layer; forming a photoresist mask on said dielectric layer; etching away said dielectric layer where it is not covered by said photoresist mask to form a dielectric mask; etching away said metal hard mask layer using said dielectric mask to form a metal hard mask; etching away said buffer metal layer using said metal hard mask to form a buffer metal mask; etching away said electrode layer using said buffer metal mask to form an electrode mask; and etching said MTJ structure using said electrode mask wherein said electrode mask remaining acts as a top electrode.

8 . The method according to claim 7 wherein said electrode layer comprises Ta, TaN, Ti, or TiN having a thickness of between about 300 and 1000 Angstroms.

9 . The method according to claim 7 wherein said buffer metal layer comprises PtMn, Ni, Cu, Mg, Ru, NiCr, NiFe, CoFeB, or CoFe alloy, having a thickness of between about 50 and 500 Angstroms.

10 . The method according to claim 7 wherein said metal hard mask layer comprises Ta, TaN, Ti, or TiN and has a thickness of between about 50 and 300 Angstroms.

11 . The method according to claim 7 wherein said dielectric layer comprises SiO 2 , SiN, or advanced patterning film having a thickness of between about 400 and 900 Angstroms.

12 . The method according to claim 7 wherein said photoresist mask has a thickness of less than about 500 to 3600 Angstroms.

13 . The method according to claim 7 wherein said dielectric layer is etched using fluoride-based chemicals.

14 . The method according to claim 7 wherein said metal hard mask layer is etched using fluoride-based chemicals.

15 . The method according to claim 7 wherein said buffer metal layer is etched using CH 3 OH-based chemicals or CO and NH 3 -based chemicals.

16 . The method according to claim 7 wherein said electrode layer is etched using fluoride-based chemicals.

17 . The method according to claim 7 wherein said MTJ stack is etched using CH OH-based chemicals or CO and NH 3 -based chemicals.

18 . A method for etching a magnetic tunneling junction (MTJ) structure comprising:
providing a stack of MTJ layers on a bottom electrode; depositing a hard mask stack comprising:
an electrode layer on said stack of MTJ layers;
a buffer metal layer on said electrode layer;
a metal hard mask layer on said buffer metal layer; and
a dielectric layer on said metal hard mask layer;
forming a photoresist mask on said hard mask stack; etching away said dielectric layer where it is not covered by said photoresist mask to form a dielectric mask; etching away said metal hard mask layer using said dielectric mask to form a metal hard mask; etching away said buffer metal layer using said metal hard mask to form a buffer metal mask; etching away said electrode layer using said buffer metal mask to form an electrode mask; and etching said MTJ structure using said electrode mask wherein said electrode mask remaining acts as a top electrode.

19 . The method according to claim 18 wherein said top electrode has a thickness of at least 38 nm.

Assignees

• Headway Tech Inc

Inventors

• Shen Dongna
• Wang Yu-Jen
• Zhong Tom

Classifications

• H01L43/12 Primary

  Electricity · mapped topic

• H10N50/01 Primary

  Manufacture or treatment · CPC title