Siloxane epoxy polymers as metal diffusion barriers to reduce electromigration

• US 7,285,842 B2
• Filed: 04/27/2004
• Issued: 10/23/2007
• Est. Priority Date: 04/27/2004
• Status: Active Grant

• Current Assignee: Polyset Company, Inc., Rensselaer Polytechnic Institute
• Original Assignee: Polyset Company, Inc., Rensselaer Polytechnic Institute
• Inventors: Lu, Toh-Ming, Ghoshal, Ramkrishna, Murarka, Shyam P., Wang, Pei-I
• Primary Examiner(s): Purvis; Sue A.
• Assistant Examiner(s): Soderholm; Krista Z.
• Application Number:
  US10/832,844
• Publication Number:
  US 20050236711A1
• Time in Patent Office: 1,274 Days
• Field of Search: None
• US Class Current: 257/642
• CPC Class Codes: H01L 21/76825 by exposing the layer to particle radiation, e.g. ion implantation, irradiation with UV light or electrons etc. plasma treatment H01L21/76826
• CPC Class Codes: H01L 21/76828 thermal treatment
• CPC Class Codes: H01L 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/76831 in via holes or trenches, e.g. non-conductive sidewall liners
• CPC Class Codes: H01L 21/76832 Multiple layers
• CPC Class Codes: H01L 21/76834 formation of thin insulating films on the sidewalls or on top of conductors H01L21/76831 takes precedence

Abstract

Structures employing siloxane epoxy polymers as diffusion barriers adjacent conductive metal layers are disclosed. The siloxane epoxy polymers exhibit excellent adhesion to conductive metals, such as copper, and provide an increase in the electromigration lifetime of metal lines. In addition, the siloxane epoxy polymers have dielectric constants less then 3, and thus, provide improved performance over conventional diffusion barriers.

Claims

1. A structure comprising

a. a conductive layer comprising a conductive metal;

b. a diffusion barrier disposed onto a surface of said conductive layer, wherein said diffusion barrier comprises a first layer and a second layer, wherein said first layer is adjacent to said second layer and to said surface of said conductive layer, and wherein said first layer and said second layer are each independently selected from the group of siloxane epoxy polymers.

2. The structure of claim 1, wherein said first layer is an adhesion promoter having a thickness ranging from about 0.001 μ

m to about 3 μ

m.

3. The structure of claim 1, wherein said first layer is an adhesion promoter having a thickness ranging from about 0.01 μ

m to about 0.03 μ

m.

4. The structure of claim 1, wherein said second layer has a thickness ranging from about 0.02 μ

m to about 10 μ

m.

5. The structure of claim 1, wherein said second layer has a thickness ranging from about 0.02 μ

m to about 0.05 μ

m.

6. The structure of claim 1, wherein said conductive metal is selected from the group consisting of aluminum, aluminum alloys, tungsten, cobalt, metal silicides, copper, and copper alloys.

7. The structure of claim 6, wherein said conductive metal is copper or a copper alloy.

8. The structure of claim 1, wherein said group of siloxane epoxy polymers consists of polymers having formulae (I) and (II)

wherein m is an integer from 5 to 50;

wherein X and Y are monomer units randomly distributed or occurring together, R¹ and R² are each independently selected from the group of methyl, methoxy, ethyl, ethoxy, propyl, butyl, pentyl, octyl, and phenyl;

R³ is methyl or ethyl;

p is an integer ranging from 2 to 50; and

q is 0 or an integer ranging from 1 to 50.

9. The structure of claim 8, wherein said first layer of said diffusion barrier is a siloxane epoxy polymer having formula (II), wherein R³ is methyl.

10. The structure of claim 9, wherein R¹ and R² are both methyl groups in formula (II), and the ratio of p to q ranges from about 8:

1 to about 1;

1.

11. The structure of claim 10, wherein the ratio of p to q ranges from about 4:

1 to about 2;

1.

12. The structure of claim 8, wherein said second layer of said diffusion barrier is a siloxane epoxy polymer having formula (II), wherein R³ is methyl.

13. The structure of claim 12, wherein R¹ and R² are both methyl groups in formula (II), and the ratio of p to q ranges from about 8:

1 to about 1;

1.

14. The structure of claim 13, wherein the ratio of p to q ranges from 4:

1 to about 2;

1.

15. The structure of claim 8, wherein said first layer of said diffusion barrier is a siloxane epoxy polymer having formula (I).

16. The structure of claim 8, wherein said second layer of said diffusion barrier is a siloxane epoxy polymer having formula (I).

17. The structure of claim 8, wherein a cationic polymerization initiator independently selected from the group consisting of diazonium, sulfonium, phosphonium, and iodonium salts is present with each said siloxane epoxy polymer of said first layer and said second layer of said diffusion barrier.

18. The structure of claim 17, wherein each said cationic polymerization initiator is an iodonium salt independently selected from the group consisting of diaryliodonium salts having formulae (III), (IV), (V), (VI), and (VII)

wherein each R¹¹ is independently hydrogen, C₁ to C₂₀ alkyl, C₁ to C₂₀ alkoxyl, C₁ to C₂₀ hydroxyalkoxyl, halogen, and nitro;

R¹² is C₁ to C₃₀ alkyl or C₁ to C₃₀ cycloalkyl;

y and z are each independently integers having a value of at least 5; and

[A]⁻

is a non-nucleophilic anion selected from the group consisting of [BF₄]⁻

, [PF₆]⁻

, [AsF₆]⁻

, [SbF₆]⁻

, [B(C₆F₅)₄]⁻

, and [Ga(C₆F₅)₄]⁻

.

19. The structure of claim 18, wherein each said selected cationic polymerization initiator is present in a catalyst solution comprising from about 20 to about 60 parts by weight of each said selected cationic polymerization initiator and from about 40 to about 80 parts by weight of 3,4-epoxycyclohexylmethyl-3′

,4′

-epoxycyclohexane carboxylate, dicyclopentadiene dioxide, or bis(3,4-epoxycyclohexyl) adipate.

20. The structure of claim 1, further comprising a dielectric material disposed on an exposed surface of said diffusion barrier.

21. The structure of claim 20, wherein said dielectric material is selected from the group consisting of polyimides, parylene (poly-p-xylylene), polynaphthalene, benzocyclobutane (BCB), silicon-containing organic polymers, aromatic hydrocarbon polymers, and siloxane epoxy polymers.