US 6,528,409 B1 · Interconnect structure formed in porous dielectric material with minimized degradation and electromigration

Abstract

For fabricating an interconnect structure within an interconnect opening formed within a porous dielectric material, the interconnect opening is initially formed within a low-K precursor material that is not completely cured. The interconnect opening is then filled with a conductive fill material being contained within the interconnect opening and with a top surface of the conductive fill material within the interconnect opening being exposed. A capping material is formed on the top surface of the conductive fill material, and the capping material is an amorphous alloy or is a microcrystalline alloy having stuffed grain boundaries. A thermal curing process is then performed for curing the low-K precursor material to become a porous low-K dielectric material. The capping material on the top surface of the conductive fill material is impervious to at least one of oxygen, carbon, hydrogen, chlorine, and porogen fragments that are generated as out-gassing volatile by-products from the low-K precursor material during the thermal curing process to preserve the integrity of the interconnect structure. In another aspect for fabricating an interconnect structure, an interconnect opening is formed within a porous dielectric material with opened pores at sidewalls of the interconnect opening. A diffusion barrier material is formed at a bottom wall of the interconnect opening. The diffusion barrier material is then sputtered away from the bottom wall of the interconnect opening and onto the sidewalls of the interconnect opening to substantially fill the opened pores at the sidewalls with the diffusion barrier material. The interconnect opening is then filled with a conductive fill material after the opened pores at the sidewalls of the interconnect opening are filled with the diffusion barrier material.

Claims67

Dependent claims

A method for fabricating an interconnect structure within an interconnect opening formed within a porous dielectric material, the method comprising the steps of:

A. forming said interconnect opening within a low-K precursor material that is not completely cured;
B. filling said interconnect opening with a conductive fill material being contained within said interconnect opening and with a top surface of said conductive fill material within said interconnect opening being exposed;
C. forming a capping material on said top surface of said conductive fill material, wherein said capping material is an amorphous alloy or is a microcrystalline alloy having stuffed grain boundaries;
and
D. performing a thermal curing process for curing said low-K precursor material to become a porous low-K dielectric material after said steps B and C;
wherein said capping material on said top surface of said conductive fill material is impervious to at least one of oxygen, carbon, hydrogen, chlorine, and porogen fragments that are generated as out-gassing volatile by-products from said low-K precursor material during said thermal curing process of said step D.

3 more elements

A method for fabricating an interconnect structure within an interconnect opening formed within a dielectric material, the method comprising the steps of:

A. forming said interconnect opening within said dielectric material comprised of silicon dioxide (SiO2) formed from TEOS (tetraethoxysilane) or from FTEOS (fluorine-doped tetraethoxysilane);
B. filling said interconnect opening with a conductive fill material being contained within said interconnect opening and with a top surface of said conductive fill material within said interconnect opening being exposed;
and
C. forming a capping material on said top surface of said conductive fill material, wherein said capping material is an amorphous alloy or is a microcrystalline alloy having stuffed grain boundaries;
wherein said capping material comprised of said amorphous alloy or said microcrystalline alloy having stuffed grain boundaries minimizes electromigration failure of said interconnect structure.

2 more elements

A method for fabricating an interconnect structure, the method comprising the steps of:

A. forming a layer of porous dielectric material and a layer of hard-mask dielectric material on said layer of porous dielectric material;
B. forming an interconnect opening through said layer of hard-mask dielectric material and said porous dielectric material with opened pores at sidewalls of said interconnect opening, wherein said interconnect opening is one of a metal line, a via hole, or a dual damascene opening having a width dimension of hundreds or tens of nanometers;
C. cleaning exposed surfaces of any dielectric material and said bottom wall of said interconnect opening with citric acid, sulfuric acid, hydrochloric acid, and water (H2O);
D. applying surfactant and water (H2O) on said bottom wall of said interconnect opening and forming an activation layer on said bottom wall of said interconnect opening, wherein said activation layer is comprised of Pd (palladium) formed in an activation solution comprised of 0.1-2 milli-liter/liter of PdCl2 (palladium chloride), 2-5 milli-liter/liter of HF (hydrofluoric acid), 1-5 milli-liter/liter of HNO3 (nitric acid), 1-30 milli-liter/liter of HCl (hydrochloric acid), and water (H2O);
E. forming a diffusion barrier material at a bottom wall of said interconnect opening, wherein said diffusion barrier material is comprised of one of CoWP (cobalt tungsten phosphide), CoWB (cobalt tungsten boride), CoMoP (cobalt molybdenum phosphide), CoMoB (cobalt molybdenum boride), CoReP (cobalt rhenium phosphide), or CoReB (cobalt rhenium boride), formed in an electroless deposition process with an electroless deposition electrolyte comprised of:
from about 10 grams/liter to about 40 grams/liter of CoSO4 (cobalt sulfate) as a cobalt source;
from about 5 grams/liter to about 20 grams/liter of ammonium tungstate or tetramethyl ammonium tungstate as a tungsten source for forming CoWP or CoWB as said diffusion barrier material, or from about 5 grams/liter to about 20 grams/liter of ammonium molybdenate or tetramethyl ammonium molybdenate as a molybdenum source for forming CoMoP or CoMoB as said diffusion barrier material, or from about 5 grams/liter to about 20 grams/liter of ammonium rhenate or tetramethyl ammonium rhenate as a rhenium source for forming CoReP or CoReB as said diffusion barrier material;
from about 70 grams/liter to about 90 grams/liter of ammonium citrate or tetramethyl ammonium citrate as a complexing agent;
from about 5 grams/liter to about 50 grams/liter of ammonium chloride or tetramethyl ammonium chloride;
from about 5 grams/liter to about 15 grams/liter of ammonium hypophosphite for a phosphorus source as a reducing agent for forming CoWP, CoMoP, or CoReP as said diffusion barrier material, or from about 5 grams/liter to about 20 grams/liter of borane dimethylamine for a boron source as a reducing agent for forming CoWB, CoMoB, or CoReB as said diffusion barrier material;
water (H2O);
and
from about 0.01 grams/liter to about 0.1 grams/liter of a surfactant;
F. sputtering said diffusion barrier material away from said bottom wall of said interconnect opening and onto said sidewalls of said interconnect opening to substantially fill said opened pores at said sidewalls with said diffusion barrier material, wherein the step of sputtering is performed in an argon sputtering process with a base pressure of 2-5×10−7 torr, with an argon gas pressure of 5-15×10−3 torr, with an argon gas flow rate of 35-45 sccm (standard cubic centimeters per minute), for a time period of 1-30 seconds for sputtering said diffusion barrier material having a thickness of about 1-30 nanometers at said bottom wall of said interconnect opening;
G. depositing an additional diffusion barrier material onto said sidewalls of said interconnect opening, wherein said additional diffusion barrier material is comprised of one of WN (tungsten nitride), TaN (tantalum nitride), or TiSiN (titanium silicon nitride) deposited in one of a CVD (chemical vapor deposition) process or an ALD (atomic layer deposition) process;
and
H. filling said interconnect opening with a conductive fill material comprised of copper deposited in an electroless deposition process with an electroless deposition electrolyte comprised of:
from about 4 grams/liter to about 10 grams/liter of CuSO4 (copper sulfate) as a copper source;
from about 10 grams/liter to about 20 grams/liter of EDTA (ethylene diamine tetra acetic acid) as a complexing agent;
from about 15 grams/liter to about 30 grams/liter of tetramethyl ammonium hydroxide as a pH adjuster;
from about 1 grams/liter to about 5 grams/liter of glyoxylic acid as a reducing agent;
water (H2O);
and
from about 0.01 grams/liter to about 0.1 grams/liter total of RE610 as a surfactant, 2,2′-dipyridyl as a stabilizer, and Triton as a wetting agent.

21 more elements

Dependencies are inferred from the claim text.

Interconnect structure formed in porous dielectric material with minimized degradation and electromigration

Life of this patent

Interconnect structure formed in porous dielectric material with minimized degradation and electromigration

Life of this patent

Abstract

Claims67