Selective formation of dielectric barriers for metal interconnects in semiconductor devices

Patent metadata

Field	Value
Publication number	US-9418889-B2
Application number	US-201514742180-A
Country	US
Kind code	B2
Filing date	Jun 17, 2015
Priority date	Jun 30, 2014
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A dielectric diffusion barrier is deposited on a substrate that has a via and an overlying trench etched into an exposed layer of inter-layer dielectric, wherein there is exposed metal from the underlying interconnect at the bottom of the via. In order to provide a conductive path from the underlying metallization layer to the metallization layer that is being formed over it, the dielectric diffusion barrier is formed selectively on the inter-layer dielectric and not on the exposed metal at the bottom of the via. In one example a dielectric SiNC diffusion barrier layer is selectively deposited on the inter-layer dielectric using a remote plasma deposition and a precursor that contains both silicon and nitrogen atoms. Generally, a variety of dielectric diffusion barrier materials with dielectric constants of between about 3.0-20.0 can be selectively formed on inter-layer dielectric.

First claim

The invention claimed is:

1. A method of processing a semiconductor substrate, the method comprising:
(a) providing a partially fabricated semiconductor substrate having an exposed layer of dielectric, and a via formed in the layer of dielectric, wherein there is an exposed layer of metal at the bottom of the via; and
(b) selectively forming a dielectric diffusion barrier layer on the exposed layer of dielectric, wherein the dielectric diffusion barrier material is selected from the group consisting of doped or undoped silicon carbide and doped or undoped silicon nitride, wherein (b) comprises using a method selected from the group consisting of:
(i) selectively depositing the dielectric diffusion barrier material on the layer of dielectric without depositing dielectric diffusion barrier layer on the layer of metal; and
(ii) depositing the dielectric diffusion barrier material on the exposed layer of dielectric while depositing less dielectric diffusion barrier material on the exposed metal layer and thereby achieving partial selectivity, and subsequently removing the dielectric diffusion barrier material over the layer of metal by etching without fully removing the dielectric diffusion barrier material over the layer of dielectric.

2. The method of claim 1 , wherein the dielectric diffusion barrier material has a dielectric constant of between about 3.0-20.0.

3. The method of claim 1 , wherein the dielectric diffusion barrier material is SiNC.

4. The method of claim 1 , wherein the semiconductor substrate provided in (a) further comprises a trench over the via.

5. The method of claim 1 , further comprising after (b):
(c) filling the via with a metal, such that the filling metal is in contact with the metal layer at the bottom of the via; and
(d) after (c), removing excess metal present on a field region of the semiconductor substrate.

6. The method of claim 5 , further comprising:
after (b) and before (c) conformally depositing a conductive liner to promote adhesion between the dielectric diffusion barrier material formed in (b), and the metal filling the via deposited in (c).

7. The method of claim 1 , wherein (b) comprises depositing the dielectric diffusion barrier material using a precursor that contains two or more of the elements that are present in the resultant dielectric diffusion barrier material.

8. The method of claim 7 , wherein (b) comprises depositing a SiCN dielectric diffusion barrier material using an aminosilane, or a carbon-containing silazane as a precursor.

9. The method of claim 7 , wherein (b) comprises depositing a SiCO dielectric diffusion barrier material using a precursor that comprises Si, C, and O atoms.

10. The method of claim 1 , wherein (b) comprises pre-treating the exposed surface of the semiconductor substrate to activate the exposed dielectric layer and/or to passivate the exposed metal layer towards deposition of the dielectric diffusion barrier material.

11. The method of claim 1 , wherein the exposed metal layer comprises copper.

12. The method of claim 1 , further comprising:
applying photoresist to the substrate;
exposing the photoresist to light;
patterning the photoresist and transferring the pattern to the substrate;
and selectively removing the photoresist from the substrate.

13. A method of processing a semiconductor substrate, the method comprising:
(a) providing a partially fabricated semiconductor substrate having an exposed layer of dielectric, and a via formed in the layer of dielectric, wherein there is an exposed layer of metal at the bottom of the via; and
(b) selectively forming a dielectric diffusion barrier layer on the exposed layer of dielectric, wherein (b) comprises using a method selected from the group consisting of:
(i) selectively depositing the dielectric diffusion barrier material on the layer of dielectric without depositing dielectric diffusion barrier layer on the layer of metal; and
(ii) depositing the dielectric diffusion barrier material on the exposed layer of dielectric while depositing less dielectric diffusion barrier material on the exposed metal layer and thereby achieving partial selectivity, and subsequently removing the dielectric diffusion barrier material over the layer of metal by etching without fully removing the dielectric diffusion barrier material over the layer of dielectric,

wherein (b) comprises:
forming a plasma in a process gas in a separate plasma chamber that does not house the semiconductor substrate;
providing radicals formed in the plasma to a process chamber housing the semiconductor substrate through a feed conduit and allowing the radicals to adsorb on the semiconductor substrate; and
providing a precursor containing at least two of the elements of the deposited dielectric diffusion barrier layer to the process chamber housing the semiconductor substrate, and allowing the precursor to react with the radicals to form the dielectric diffusion barrier layer selectively or partially selectively.

14. The method of claim 13 , wherein the process gas comprises H 2 .

15. The method of claim 13 , wherein the precursor is an aminosilane and the formed dielectric diffusion barrier material is SiCN.

16. A method of processing a semiconductor substrate, the method comprising:
(a) providing a partially fabricated semiconductor substrate having an exposed layer of dielectric, and a via formed in the layer of dielectric, wherein there is an exposed layer of metal at the bottom of the via; and
(b) selectively forming a dielectric diffusion barrier layer on the exposed layer of dielectric, wherein the dielectric diffusion barrier material is AlN, wherein (b) comprises using a method selected from the group consisting of:
(i) selectively depositing the dielectric diffusion barrier material on the layer of dielectric without depositing dielectric diffusion barrier layer on the layer of metal; and
(ii) depositing the dielectric diffusion barrier material on the exposed layer of dielectric while depositing less dielectric diffusion barrier material on the exposed metal layer and thereby achieving partial selectivity, and subsequently removing the dielectric diffusion barrier material over the layer of metal by etching without fully removing the dielectric diffusion barrier material over the layer of dielectric.

17. The method of claim 16 , wherein (b) comprises pre-treating the exposed surface of the semiconductor substrate to activate the exposed dielectric layer and/or to passivate the exposed metal layer towards deposition of the dielectric diffusion barrier material.

18. The method of claim 17 , wherein the dielectric diffusion barrier material is AlN deposited using trimethylaluminum as a precursor.

19. The method of claim 16 , further comprising after (b):
(c) filling the via with a metal, such that the filling metal is in contact with the metal layer at the bottom of the via; and
(d) after (c), removing excess metal present on a field region of the semiconductor substrate.

20. The method of claim 19 , further comprising:
after (b) and before (c) conformally depositing a conductive liner to promote adhesion between the dielectric diffusion barrier material formed in (b), and the metal filling the via deposited in (c).

Assignees

• Lam Res Corp

Inventors

• Mountsier Thomas Weller
• Wu Hui-Jung
• Varadarajan Bhadri N
• Shankar Nagraj
• Lee William T

Classifications

• H10P95/00

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

• H10P50/283

  by chemical means · CPC title

• H10P14/69433

  the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz · CPC title

• H10P14/69391

  the material containing aluminium, e.g. Al2O3 · CPC title

• H10P14/6922

  the material containing Si, O and at least one of H, N, C, F or other non-metal elements, e.g. SiOC, SiOC:H or SiONC · CPC title