Systems and methods for selectively etching tungsten in a downstream reactor

Patent metadata

Field	Value
Publication number	US-9837286-B2
Application number	US-201615014539-A
Country	US
Kind code	B2
Filing date	Feb 3, 2016
Priority date	Sep 4, 2015
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A method for selectively etching a tungsten layer on a substrate includes arranging a substrate including a tungsten layer on a substrate support. The substrate processing chamber includes an upper chamber region, an inductive coil arranged outside of the upper chamber region, a lower chamber region including the substrate support and a gas dispersion device arranged between the upper and lower chamber regions. The gas dispersion device includes a plurality of holes in fluid communication with the upper and lower chamber regions. The method further includes controlling pressure in the substrate processing chamber in a range from 0.4 Torr to 10 Torr; supplying an etch gas mixture including fluorine-based gas to the upper chamber region; striking inductively coupled plasma in the upper chamber region by supplying power to the inductive coil; and selectively etching the tungsten layer relative to at least one other film material of the substrate.

First claim

What is claimed is:

1. A method comprising:
arranging a substrate including a plurality of stacks of layers arranged adjacent to each other on a substrate support of a substrate processing chamber, a distance separating the plurality of stacks being less than a height of the plurality of stacks, and each of the plurality of stacks including N sets of layers, each of the N sets including layers in the following order, N being an integer greater than 1:
an oxide layer,
a first barrier layer,
a tungsten layer, and
a second barrier layer,

wherein the substrate processing chamber includes an upper chamber region, an inductive coil arranged outside of the upper chamber region, a lower chamber region including the substrate support and a gas dispersion device arranged between the upper chamber region and the lower chamber region, and
wherein the gas dispersion device includes a plurality of holes in fluid communication with the upper chamber region and the lower chamber region;
controlling pressure in the substrate processing chamber in a range from 0.4 Torr to 10 Torr;
supplying an etch gas mixture including fluorine-based gas to the upper chamber region;
striking inductively coupled plasma in the upper chamber region by supplying power to the inductive coil; and
selectively etching, in each of the plurality of stacks, the tungsten layers and the first and second barrier layers inwardly relative to the oxide layers while preventing etching of voids in the tungsten layers if the tungsten layers include voids.

2. The method of claim 1 , wherein the oxide layers include silicon nitride, silicon dioxide, metal oxide or carbon.

3. The method of claim 1 , wherein the etch gas mixture includes molecular hydrogen and a gas selected from a group consisting of carbon tetrafluoride, nitrogen trifluoride, and sulfur hexafluoride.

4. The method of claim 3 , wherein the each of the plurality of stacks includes a hard mask layer and wherein the tungsten layers are selectively etched relative to the hard mask layers.

5. The method of claim 4 , wherein the hard mask layers are made of a material selected from a group consisting of silicon nitride, silicon dioxide and carbon.

6. The method of claim 3 , wherein the selective etching of the tungsten layers is greater than 100:1.

7. The method of claim 1 , wherein the etch gas mixture includes a first gas selected from a group consisting of molecular chlorine, molecular oxygen and molecular nitrogen and a second gas selected from a group consisting of carbon tetrafluoride, nitrogen trifluoride, sulfur hexafluoride, fluoromethane and difluoromethane.

8. The method of claim 7 , wherein the selective etching of the tungsten layers is greater than 100:1, and etching of the tungsten layers relative to the first and second barrier layers is between 0.9:1 and 1.1:1.

9. The method of claim 7 , wherein the first gas includes both molecular oxygen and molecular nitrogen.

10. The method of claim 7 , further comprising:
supplying the first gas including one of molecular oxygen and molecular nitrogen with the second gas during a first predetermined etch period; and
after the first predetermined etch period, supplying the first gas including the other one of molecular oxygen and molecular nitrogen with the second gas during a second predetermined etch period.

11. The method of claim 10 , wherein the first predetermined period and the second predetermined period are in a range from five seconds to 60 seconds.

12. The method of claim 11 , wherein the plurality of holes have diameters in a range from 0.4″ to 0.75″.

13. The method of claim 1 , wherein a radio frequency (RF) bias is supplied to the substrate support.

14. The method of claim 1 , wherein a radio frequency (RF) bias is not supplied to the substrate support.

15. The method of claim 1 , wherein the etch gas mixture includes one or more additive gases selected from a group consisting of argon, helium, and molecular nitrogen.

16. The method of claim 1 , wherein the gas dispersion device includes a showerhead plate including a plurality of holes.

17. The method of claim 1 , wherein a gas injector is arranged adjacent to an upper surface of the upper chamber region to inject the etch gas mixture, the gas dispersion device is arranged adjacent to a lower surface of the upper chamber region, and the gas dispersion device is connected to a reference potential.

18. The method of claim 1 , wherein the etch gas mixture further comprises molecular chlorine.

19. The method of claim 1 , wherein the first and second barrier layers are made of titanium or titanium nitride.

20. A method comprising:
arranging a substrate including a plurality of stacks of layers arranged adjacent to each other on a substrate support of a substrate processing chamber, a distance separating the plurality of stacks being less than a height of the plurality of stacks, and each of the plurality of stacks including N sets of layers, each of the N sets including layers in the following order, N being an integer greater than 1:
an oxide layer,
a first barrier layer,
a tungsten layer, and

a second barrier layer,
wherein the substrate processing chamber includes an upper chamber region, an inductive coil arranged outside of the upper chamber region, a lower chamber region including the substrate support and a gas dispersion device arranged between the upper chamber region and the lower chamber region, and
wherein the gas dispersion device includes a plurality of holes in fluid communication with the upper chamber region and the lower chamber region;
controlling pressure in the substrate processing chamber in a range from 0.4 Torr to 10 Torr;
supplying an etch gas mixture to the upper chamber region, wherein the etch gas mixture includes carbon monoxide;
striking inductively coupled plasma in the upper chamber region by supplying power to the inductive coil; and
selectively etching, in each of the plurality of stacks, the tungsten layers and the first and second barrier layers inwardly relative to the oxide layers while preventing etching of voids in the tungsten layers if the tungsten layers include voids.

Assignees

• Lam Res Corp

Inventors

• Yang Dengliang
• Zhu Helen H
• Matamis George
• Jacobs Brad
• Park Joon Hong
• Guha Joydeep

Classifications

• H10P72/0421

  for drying etching · CPC title

• H10P70/273

  the processing being a delineation of conductive layers, e.g. by RIE · CPC title

• H10P50/287

  by chemical means · CPC title

• H10P50/283

  by chemical means · CPC title

• H10P50/242

  of Group IV materials · CPC title