Tungsten feature fill

Patent metadata

Field	Value
Publication number	US-11075115-B2
Application number	US-201816124050-A
Country	US
Kind code	B2
Filing date	Sep 6, 2018
Priority date	Aug 4, 2009
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

Described herein are methods of filling features with tungsten and related systems and apparatus. The methods include inside-out fill techniques as well as conformal deposition in features. Inside-out fill techniques can include selective deposition on etched tungsten layers in features. Conformal and non-conformal etch techniques can be used according to various implementations. The methods described herein can be used to fill vertical features, such as in tungsten vias, and horizontal features, such as vertical NAND (VNAND) word lines. Examples of applications include logic and memory contact fill, DRAM buried word line fill, vertically integrated memory gate/word line fill, and 3-D integration with through-silicon vias (TSVs).

First claim

The invention claimed is:

1. A method comprising:
providing a substrate including a feature including an underlayer on sidewalls of the feature;
depositing a first bulk tungsten layer in the feature to partially fill the feature with the first bulk tungsten layer;
etching a portion of the first bulk tungsten layer to leave an etched tungsten layer in the feature, including removing tungsten from the underlayer to expose a portion of surfaces of the underlayer while leaving the underlayer on sidewalls, wherein etching comprises exposing the first bulk tungsten layer to plasma etchant species; and
depositing a second bulk tungsten layer on the etched tungsten layer, wherein the deposition of the second bulk tungsten layer is preferential on surfaces of the etched tungsten layer with respect to exposed underlayer surfaces on the sidewalls from which tungsten is removed.

2. The method of claim 1 , wherein depositing the first bulk tungsten layer includes allowing a void to be formed within the first bulk tungsten layer.

3. The method of claim 2 , wherein etching the portion of the first bulk tungsten layer includes opening the void.

4. The method of claim 1 , wherein depositing the first bulk tungsten layer includes allowing a seam running along the axis of the feature in the first bulk tungsten layer to be formed.

5. The method of claim 4 , wherein etching the portion of the first bulk tungsten layer includes etching the first tungsten bulk layer to remove tungsten through the point of seam formation.

6. The method of claim 1 , wherein depositing the second bulk tungsten layer on the etched tungsten layer includes depositing the second bulk tungsten layer on the etched tungsten layer without forming a nucleation layer in the feature after etching the portion of the first bulk tungsten layer.

7. The method of claim 1 , wherein the feature is a vertical feature.

8. The method of claim 1 , wherein the feature is a horizontal feature.

9. The method of claim 1 , wherein etching the portion of the first tungsten bulk layer includes exposing the first tungsten bulk layer to radical species.

10. The method of claim 1 , wherein etching the portion of the first tungsten bulk layer includes exposing the first tungsten bulk layer to a remotely-generated plasma.

11. The method of claim 1 , wherein etching the portion of the first bulk tungsten layer includes non-conformal etching of the first bulk tungsten layer.

12. The method of claim 1 , wherein etching the portion of the first bulk tungsten layer includes conformal etching of the first bulk tungsten layer.

13. The method of claim 1 , wherein etching the portion of the first bulk tungsten layer includes selectively etching tungsten with respect to an under-layer lining the feature on which the first tungsten bulk layer is deposited.

14. The method of claim 1 , wherein the first bulk tungsten layer is deposited through a constriction and etching the first bulk tungsten layer comprises etching through the constriction to leave an etched tungsten layer in the feature beyond the constriction.

15. The method of claim 1 , wherein depositing the first bulk tungsten layer comprises allowing a seam or void to be formed in the first bulk tungsten layer, and further wherein if the feature comprises a constriction, a void is allowed to be formed in the first bulk tungsten layer.

16. The method of claim 1 , wherein partially filling the feature with the first bulk tungsten layer comprises filling the feature to a feature top with a void or seam formed in the first bulk tungsten layer.

17. A method comprising:
providing a substrate including a feature including an opening and a constriction;
depositing a first bulk tungsten layer in the feature through the constriction to partially fill the feature with the first bulk tungsten layer;
etching the first bulk tungsten layer through the constriction to leave an etched tungsten layer in the feature beyond the constriction, wherein etching comprises exposing the first bulk tungsten layer to plasma etchant species; and
selectively depositing a second bulk tungsten layer on the etched tungsten layer.

18. The method of claim 17 , wherein depositing the first bulk tungsten layer comprises allowing void to be formed in the first bulk tungsten layer.

19. A method comprising:
providing a substrate including a feature including sidewalls;
depositing a first bulk tungsten layer in the feature, including depositing tungsten on the sidewalls to partially fill the feature with the first bulk tungsten layer;
etching the first bulk tungsten layer to form an etched tungsten layer, wherein etching the first bulk tungsten layer includes removing tungsten in the feature including removing tungsten from the sidewalls to expose surfaces of the sidewalls up to a recess depth, wherein etching comprises exposing the first bulk tungsten layer to plasma etchant species; and
depositing a second bulk tungsten layer in the feature.

20. The method of claim 19 , wherein the first bulk tungsten layer only partially fills the feature.

21. The method of claim 20 , wherein etching the first bulk tungsten layer comprises lateral etching of a region of the first bulk layer.

22. The method of claim 19 , wherein the second bulk tungsten layer is selectively deposited on the etched tungsten layer.

Assignees

• Novellus Systems Inc

Inventors

• Chandrashekar Anand
• Jeng Esther
• Humayun Raashina
• Danek Michal
• Gao Juwen
• Wang Deqi

Classifications

• H10W20/0595

  by using multiple deposition steps separated by etching steps · CPC title

• H10W20/0261

  characterised by the filling method or the material of the conductive fill · CPC title

• H10P95/00

  Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass · CPC title

• H10P50/267

  using plasmas · CPC title

• H10P50/264

  by chemical means · CPC title