Interconnect structures having tantalum/tantalum oxide layers

• US 5,436,504 A
• Filed: 05/19/1993
• Issued: 07/25/1995
• Est. Priority Date: 05/07/1990
• Status: Expired due to Term

• Current Assignee: Yakisami Capital Co LLC (Intellectual Ventures LLC)
• Original Assignee: The Boeing Co.
• Inventors: Tanielian, Minas H., Chakravorty, Kishore K.
• Primary Examiner(s): LARKINS, WILLIAM
• Application Number:
  US08/064,794
• Time in Patent Office: 797 Days
• Field of Search: 357/71, 357/68, 357/23.7, 257/752, 257/758, 257/759, 257/761, 257/762, 174/256, 174/257, 174/258, 174/266, 361/750, 361/751
• US Class Current: 257/758
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/4846 Leads on or in insulating or insulated substrates, e.g. metallisation H01L21/4821 takes precedence; metallisation of ceramics in general C04B41/51; printed circuits H05K3/00
• CPC Class Codes: H01L 21/76879 by selective deposition of conductive material in the vias, e.g. selective C.V.D. on semiconductor material, plating plating on semiconductors in general H01L21/288

Abstract

A method of fabricating a high-density multilayer copper/polyimide interconnect structure utilizing a blanket tantalum/tantalum oxide layer that electrically connects all of the electroplating seed layers to the edge of the substrate; upon completion of the electroplating process, the excess tantalum/tantalum oxide layer is etched off to produce isolated conductor lines. A multilayer copper/polyimide interconnect structure may be fabricated by repeating this fabrication sequence for each layer.

Claims

1. A metal/dielectric high-density interconnect structure produced by the method comprising the steps:

(a) providing a substrate coated on its upper surface with patterned electroplating seed layers, and a photosensitive dielectric layer photopatterned thereover, which exposes the electroplating seed layers through trenches in the dielectric layer, the electroplating seed layers being conductive;

(b) depositing on and within the trenches of said dielectric layer and on said exposed electroplating seed layers a substantially continuous layer of tantalum;

(c) forming a substantially continuous layer of anodic tantalum oxide on said tantalum layer to produce a tantalum/tantalum oxide layer;

(d) patterning said tantalum/tantalum oxide layer to expose said electroplating seed layers while maintaining electrical connection between said electroplating seed layers and said tantalum layer;

(e) electroplating a metal conductor on said electroplating seed layers to form a pattern of unexposed and exposed tantalum/tantalum oxide layers, the unexposed tantalum/tantalum oxide layers being covered by the metal conductor; and

(f) removing the exposed tantalum/tantalum oxide layers to electrically isolate said metal conductor lines, and to thereby produce a planar interconnect structure, wherein the tantalum/tantalum oxide layers remain within the trenches between the dielectric layer and the conductor.

2. The structure of claim 1, wherein the dielectric is a polyimide and the metal is copper.

3. A multi-layer metal/dielectric high-density interconnect structure produced according to the method comprising the steps:

(a) providing a substrate coated on its upper surface with patterned electroplating seed layers covered by a photosensitive dielectric layer, and photopatterning trenches in the dielectric layer to thereby expose the electroplating seed layers, followed by baking the substrate to harden the dielectric layer;

(b) depositing on and within the trenches of said dielectric layer and on said exposed electroplating seed layers a substantially continuous layer of tantalum;

(c) forming a substantially continuous layer of anodic tantalum oxide on said tantalum layer to produce a tantalum/tantalum oxide layer;

(d) patterning said tantalum/tantalum oxide layer to expose said electroplating seed layers while maintaining electrical connection between said electroplating seed layers and said tantalum layer;

(e) electroplating a metal conductor on said electroplating seed layers to form a pattern of unexposed and exposed tantalum/tantalum oxide layers, the unexposed tantalum/tantalum oxide layers being covered by the metal conductor;

(f) removing the exposed tantalum/tantalum oxide layers to electrically isolate said metal conductor lines, thereby producing a planar interconnect structure, wherein the tantalum/tantalum oxide layers remain within the trenches between the dielectric layer and the conductor; and

(g) combining a plurality of said planar interconnect structures to form a multilayer/dielectric high-density interconnect structure.

4. The structure of claim 3, wherein the dielectric is a polyimide and the metal is copper.

5. An interconnect structure comprising copper conductors within trenches in a patterned insulator, the conductors being isolated from the patterned insulator by a layer of tantalum metal coating the insides of the trenches between the insulator and the conductors and a layer of anodic tantalum oxide overlying the layer of tantalum metal within the trenches, the layer of anodic tantalum oxide being disposed between the tantalum metal and the conductors.

6. An interconnect structure comprising conductors within trenches in a patterned insulator, the conductors being isolated from the patterned insulator by a layer of tantalum metal coating the insides of the trenches between the insulator and the conductors and a layer of anodic tantalum oxide overlying the layer of tantalum metal within the trenches, the layer of anodic tantalum oxide being disposed between the tantalum metal and the conductors and, wherein the insulator is polyimide.

7. An interconnect structure, comprising:

a substrate;

at least one seed layer overlying a portion of the substrate, said seed layer comprising a material suitable for electroplating a conductive metal;

a copper conductor deposited on the seed layer and having a base in contact with the seed layer and lateral sidewalls defining a conductor height;

a layer of anodic tantalum oxide adjacent and contacting the sidewalls;

a layer of tantalum adjacent and contacting the layer of anodic tantalum oxide; and

an insulator overlying the substrate, the insulator having at least one trench extending through the insulator to the seed layer, the conductor being disposed within the trench, the lateral sides of the trench being in contact with the tantalum and extending to the height of the sidewalls, the layer of tantalum being disposed between the sides of the insulator trench and the layer of anodic tantalum oxide.

8. An interconnect structure, comprising;

a substrate;

at least one seed layer overlying a portion of the substrate, said seed layer comprising a material suitable for electroplating a conductive metal;

a conductor deposited on the seed layer and having a base in contact with the seed layer and lateral sidewalls defining a conductor height;

a layer of anodic tantalum oxide adjacent and contacting the sidewalls;

a layer of tantalum adjacent and contacting the layer of anodic tantalum oxide; and

a polyimide insulator overlying the substrate, the insulator having at least one trench extending through the insulator to the seed layer, the conductor being disposed within the trench, the lateral sides of the trench being in contact with the tantalum and extending to the height of the sidewalls, the layer of tantalum being disposed between the sides of the insulator trench and the layer of anodic tantalum oxide.

9. An interconnect structure, comprising:

a substrate, wherein the substrate is comprised of insulating material;

a seed layer overlying a portion of the substrate;

a first dielectric layer overlying the substrate and having a trench extending through a portion of the dielectric layer such that the seed layer is not completely covered by the dielectric layer, the trench having sidewalls;

a tantalum layer coating each of the sidewalls within the trench and extending from the seed layer;

a tantalum oxide layer coating at least a portion of the tantalum layer on each of the sidewalls within the trench; and

a conductor deposited on the seed layer between the tantalum oxide layer on each of the sidewalls within the trench, wherein the seed layer is formed of conductive material other than tantalum and other than the conductor, and the conductor is a conductive metal other than tantalum.

10. The interconnect structure of claim 9 wherein the dielectric layer includes a plurality of trenches with sidewalls, each trench having a seed layer disposed at the bottom thereof on the substrate, the interconnect structure further comprising a conductor within each of the trenches with a layer of tantalum and a layer of tantalum oxide coating the sidewalls of the trenches between the conductor and the dielectric layer.

11. The interconnect structure of claim 10, further comprising a second dielectric layer overlying the first dielectric layer, said second dielectric layer having trenches with sidewalls extending therethrough with tantalum and tantalum oxide layers coating the sidewalls and conductors disposed in the trenches between the tantalum and tantalum oxide layers.