High aspect ratio etch of oxide metal oxide metal stack

Patent metadata

Field	Value
Publication number	US-10242883-B2
Application number	US-201715632163-A
Country	US
Kind code	B2
Filing date	Jun 23, 2017
Priority date	Jun 23, 2017
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A method for etching features in an OMOM stack with first layer of silicon oxide, a second layer of a metal containing material over the first layer, a third layer of silicon oxide over the second layer, and a fourth layer of a metal containing material over the third layer is provided. A hardmask is formed over the stack. The hardmask is patterned. The OMOM stack is etched through the hardmask.

First claim

What is claimed is:

1. A method for etching features, comprising:
forming a hardmask over an OMOM stack, the OMOM stack comprising a first layer of silicon oxide, a second layer of a metal containing material over the first layer, a third layer of silicon oxide over the second layer, and a fourth layer of a metal containing material over the third layer, wherein the forming a hardmask over the stack, comprises:
forming a first mask layer comprising a metal containing material over the stack;
forming a second mask layer comprising carbon or silicon oxide over the first mask layer;
forming a third mask layer comprising a metal containing material over the second mask layer; and
forming a fourth mask layer comprising carbon or silicon oxide over the third mask layer;

patterning the hardmask; and
etching the OMOM stack through the hardmask.

2. The method, as recited in claim 1 , wherein the patterning the hardmask, comprises:
flowing a hardmask etch gas comprising a halogen component; and
forming the hardmask etch gas into a plasma, which etches the first mask layer, the second mask layer, the third mask layer, and the fourth mask layer, which forms the first mask layer into a first patterned mask, and forms the second mask layer into a second patterned mask, and forms the third mask layer into a third patterned mask, and forms the fourth mask layer into a fourth patterned mask; and
stopping the flow of the hardmask etch gas.

3. The method, as recited in claim 2 , wherein the etching the stack through the hardmask, comprises:
etching the fourth layer using the fourth patterned mask;
etching the third layer using the third patterned mask, wherein the etching the third layer removes the fourth patterned mask;
etching the second layer using the second patterned mask, wherein the etching the second layer removes the third patterned mask; and
etching the first layer using the first patterned mask, wherein the etching the first layer removes the second patterned mask.

4. The method, as recited in claim 3 , wherein the second layer and the fourth layer each have a resistivity of less than 10 −5 Ohm*m.

5. The method, as recited in claim 4 , wherein the second layer and the fourth layer are a metal, a metal alloy, a metal oxide or metal nitride.

6. The method, as recited in claim 4 , wherein the second layer and fourth layer are at least one of titanium, titanium nitride, tungsten, tin, tin oxide, ruthenium, tantalum.

7. The method, as recited in claim 5 , wherein the third layer has a thickness and wherein the first, second, third, and fourth mask layers each have a thickness less than half the thickness of the third layer.

8. The method, as recited in claim 4 , wherein the second mask layer and fourth mask layer are silicon oxide.

9. The method, as recited in claim 4 , wherein the first mask layer and the third mask layer each have a resistivity of less than 10 −5 Ohm*m.

10. The method, as recited in claim 4 , wherein the third mask layer is of the same material as the second layer, so that the etching of the second layer removes the third mask layer.

11. The method, as recited in claim 10 , wherein the first mask layer is of the same material as the third mask layer.

12. The method, as recited in claim 2 , further comprising forming a carbon buffer layer over the stack before forming the first mask layer, and wherein the carbon buffer layer is used as an etch stop during patterning the hardmask.

13. The method, as recited in claim 1 , wherein the forming the first mask layer forms the first mask layer by chemical vapor deposition, and wherein the forming the second mask layer forms the second mask layer by chemical vapor deposition, and wherein the forming the third mask layer forms the third mask layer by chemical vapor deposition and wherein the forming the fourth mask layer forms the fourth mask layer by chemical vapor deposition.

14. The method, as recited in claim 2 , wherein the etching the stack through the hardmask, comprises:
etching the fourth layer using the fourth patterned mask;
etching the third layer using the third patterned mask, wherein the etching the third layer removes the fourth patterned mask;
etching the second layer using the second patterned mask, wherein the etching the second layer removes the third patterned mask; and
etching the first layer using the first patterned mask, wherein the etching the first layer removes the second patterned mask.

15. The method, as recited in claim 1 , wherein the third layer has a thickness and wherein the first, second, third, and fourth mask layers each have a thickness less than half the thickness of the third layer.

16. The method, as recited in claim 1 , wherein the second mask layer and fourth mask layer are silicon oxide.

17. The method, as recited in claim 1 , wherein the third mask layer is of the same material as the second layer, so that the etching of the second layer removes the third mask layer.

18. The method, as recited in claim 17 , wherein the first mask layer is of the same material as the third mask layer.

Assignees

• Lam Res Corp

Inventors

• Guha Joydeep
• Reddy Sirish K
• Chattopadhyay Kaushik
• Mountsier Thomas W
• Eppler Aaron
• Lill Thorsten
• Vahedi Vahid
• Singh Harmeet

Classifications

• H10P50/695

  characterised by the process involved to create the mask, e.g. lift-off masks or sidewalls or to modify the mask · CPC title

• H10P50/692

  characterised by their composition, e.g. multilayer masks or materials · CPC title

• H10P50/642

  Chemical etching · CPC title

• H10P50/285

  of materials not containing Si, e.g. PZT or Al2O3 · CPC title

• H10P50/283

  by chemical means · CPC title