Copper conductor annealing process employing high speed optical annealing with a low temperature-deposited optical absorber layer

• US 20070032095A1
• Filed: 08/08/2005
• Published: 02/08/2007
• Est. Priority Date: 08/08/2005
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Collins, Kenneth, Ramaswamy, Kartik, Hanawa, Hiroji, Nguyen, Andrew, Al-Bayati, Amir, Parihar, Vijay, Jennings, Dean, Gallo, Biagio, Ma, Kai, Mayur, Abhilash
• Granted Patent: US 7,335,611 B2
• Time in Patent Office: Days
• US Class Current: 438/795
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/0608 in the same heat affected zone [HAZ] B23K26/0613, B23K26/0619 take precedence
• CPC Class Codes: B23K 26/0738 into a linear shape
• CPC Class Codes: B23K 26/0876 in at least two axial directions
• CPC Class Codes: B23K 26/361 for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76864 Thermal treatment
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 21/76886 Modifying permanently or temporarily the pattern or the conductivity of conductive members, e.g. formation of alloys, reduction of contact resistances

Abstract

A method of forming a conductor in a thin film structure on a semiconductor substrate includes forming high aspect ratio openings in a base layer having vertical side walls, depositing a dielectric barrier layer comprising a dielectric compound of a barrier metal on the surfaces of the high aspect ratio openings including the vertical side walls, depositing a metal barrier layer comprising the barrier metal on the first barrier layer, depositing a main conductor species seed layer on the metal barrier layer and depositing a main conductor layer. The method further includes annealing the main conductor layer by (a) directing light from an array of continuous wave lasers into a line of light extending at least partially across the thin film structure, and (b) translating the line of light relative to the thin film structure in a direction transverse to the line of light. The method of Claim 1 further comprising, prior to the annealing step, depositing an amorphous carbon optical absorber layer on the main conductor layer. The step of depositing an amorphous carbon optical absorber layer includes introducing a carbon-containing process gas into a reactor chamber containing the substrate in a process zone of the reactor, applying RF source power to an external reentrant conduit of the reactor to generate a reentrant toroidal RF plasma current passing through the process zone and applying a bias voltage to the substrate.

Claims

1. A method of forming a conductor in a thin film structure on a semiconductor substrate, said method comprising:

forming high aspect ratio openings in a base layer having vertical side walls;

depositing a dielectric barrier layer comprising a dielectric compound of a barrier metal on the surfaces of said high aspect ratio openings including said vertical side walls;

depositing a metal barrier layer comprising said barrier metal on said first barrier layer;

depositing a main conductor species seed layer on on the metal barrier layer;

depositing a main conductor layer; and

annealing said main conductor layer by;

(a) directing light from an array of continuous wave lasers into a line of light extending at least partially across said thin film structure,

(b) translating said line of light relative to said thin film structure in a direction transverse to said line of light.

2. The method of claim 1 further comprising, prior to the annealing step, depositing an amorphous carbon optical absorber layer on said main conductor layer.

3. The method of claim 2 wherein the step of depositing an amorphous carbon optical absorber layer comprises:

introducing a carbon-containing process gas into a reactor chamber containing said substrate in a process zone of the reactor;

applying RF source power to an external reentrant conduit of the reactor to generate a reentrant toroidal RF plasma current passing through said process zone; and

applying a bias voltage to the substrate.

4. The method of claim 2 further comprising, prior to the step of depositing the amorphous carbon optical absorber layer, chemical mechanical polishing a top surface of the main conductor layer.

5. The method of claim 1 wherein said barrier metal comprises tantalum nitride and said main conductor species comprises copper.

6. The method of claim 1 wherein the step of annealing said main conductor layer comprises heating at least a surface portion of said main conductor layer to the melting temperature of copper.

7. The method of claim 1 wherein the step of depositing a main conductor layer forms metallic grains having a wide grain size variation of about an order of magnitude, and wherein the step of annealing the main conductor layer reduces the grain size variation so that grain size in the main conductor layer is generally uniform at a single grain size.

8. The method of claim 7 wherein said grain size variation is reduced in the annealing step from an initial range of about 2 nm to 200 nm to a generally uniform grain size of about 100 nm.

9. The method of claim 1 wherein:

said line of light lies parallel to a slow axis and the step of translating said line of light translates the line of light along a fast axis;

the step of directing light from an array of continuous wave lasers comprises;

(a) collimating light along said fast axis from respective rows of said laser at respective cylindrical lenslets on respective rows of lasers,

(b) homogenizing light along said slow axis from the respective cylindrical lenslets in a homogenizing light pipe providing plural reflections along said slow axis and minimal or no reflections along said fast axis.

10. The method of claim 1 further comprising:

depositing a metal seed layer of a main conductor metal species over said metal barrier layer;

reflowing said metal seed layer by;

(a) directing light from an array of continuous wave lasers into a line of light extending at least partially across said thin film structure,

(b) translating said line of light relative to said thin film structure in a direction transverse to said line of light.

11. The method of claim 3 wherein the step of introducing the carbon-containing process gas comprises introducing the process gas through a gas distribution plate overlying the workpiece and underlying the external portion of the reentrant path.

12. The method of claim 3 wherein said process gas comprises a hydrogen-carbon chemical species.

13. The method of claim 3 further comprising setting conductivity of the carbon layer between insulative and semiconductive by at least one of:

(1) adjusting the ion bombardment energy at the wafer surface,

(2) adjusting the workpiece temperature,

(3) selecting the hydrogen-carbon gas species of the process gas in accordance with a hydrogen-carbon ratio of the gas,

(4) diluting the process gas with hydrogen,

(5) diluting the process gas with an inert gas such as helium, neon, argon or xenon,

(6) adjusting the flux of energetic ions at the wafer surface relative to the flux of carbon-containing radical species to the wafer surface,

(7) adding to the process gas a precursor additive gas of one of;

(a) a semi-conductivity-enhancing species, (b) a resistivity-enhancing species;

(8) implanting in the deposited carbon layer one of;

(a) a semiconductivity-enhancing species, (b) a resistivity-enhancing species.

14. The method of claim 3 further comprising setting the transparency or opacity of the carbon layer by at least one of:

(1) adjusting the ion bombardment energy at the wafer surface,

(2) adjusting the workpiece temperature,

(3) selecting the hydrogen-carbon gas species of the process gas in accordance with a hydrogen-carbon ratio of the gas,

(4) diluting the process gas with hydrogen,

(5) diluting the process gas with an inert gas such as helium, neon, argon or xenon,

(6) adjusting the flux of energetic ions at the wafer surface relative to the flux of carbon-containing radical species to the wafer surface,

(7) adding to the process gas a precursor additive gas of one of;

(a) an absorption-enhancing species, (b) a transparency-enhancing species;

(8) implanting in the deposited carbon layer one of;

(a) an absorption-enhancing species, (b) a transparency-enhancing species.

15. The method of claim 14 wherein the absorption-enhancing species is one of boron, nitrogen, sulfur.

16. The method of claim 14 wherein the transparency-enhancing species is fluorine.

17. The method of claim 3 further comprising enhancing the adhesion of the deposited carbon layer to the underlying workpiece by setting the bias power or bias voltage to a sufficiently high level.

18. The method of claim 3 further comprising setting stress within the deposited carbon layer to one of compressive stress and tensile stress by adjusting the bias power or bias voltage.

19. The method of claim 3 further comprising increasing compressive stress in the deposited carbon layer by increasing said bias power or bias voltage.

20. The method of claim 3 further comprising controlling the conformality of the deposited carbon layer by setting the level of said RF plasma source power.