Method of Bonding Metals to Ceramics

Abstract

A metal layer is bonded to a ceramic substrate in a method, wherein a first metal layer (e.g., a copper film) is first applied to a surface of the ceramic substrate. The ceramic substrate, with the first metal layer applied thereto, is then heated in an atmosphere including oxygen (e.g., to a temperature below the eutectic temperature of the metal oxide) to form an adhesion-promotion layer. A second metal layer (e.g., a copper foil) is then bonded to the adhesion-promotion layer. Where the metal is copper, the adhesion promotion layer can include copper oxide and copper aluminum oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional illustration of a substrate with an adhesion-promotion layer bonded to the substrate and with a metal layer bonded to the adhesion-promotion layer.

FIG. 2 is a flow chart illustrating a process for bonding a metal to a ceramic substrate.

FIG. 3 is a sectional illustration of a substrate with a metal film coated thereon.

FIG. 4 is an x-ray diffraction chart from x-ray diffraction performed on an adhesion promotion layer, with illustrated markers for copper aluminum oxide and for copper oxide.

FIG. 5 is a phase diagram for a binary system of aluminum oxide and copper oxide.

Claims

1. A method of bonding a metal layer to a ceramic substrate: providing a ceramic substrate, a first metal layer and a second metal layer;applying the first metal layer onto the ceramic substrate;heating the ceramic substrate with the first metal layer applied thereto in an atmosphere including oxygen to form an adhesion-promotion layer; andbonding the second metal layer to the adhesion-promotion layer.

2. The method of claim 1, further comprising de-oxidizing the adhesion-promotion layer before bonding the second metal layer to it.

3. The method of claim 1, wherein the first metal layer is applied at a temperature of about 100° C. or less.

4. The method of claim 1, wherein the first metal layer comprises copper.

5. The method of claim 4, wherein the adhesion promotion layer includes copper oxide.

6. The method of claim 5, wherein the adhesion promotion layer further includes copper aluminum oxide.

7. The method of claim 5, wherein the ceramic substrate with the film applied thereto is heated to a temperature no greater than about 1,000° C.

8. The method of claim 1, wherein the ceramic substrate with the first metal layer is applied thereto is heated to a temperature below the eutectic temperature of the metal-oxide system.

9. The method of claim 1, wherein the substrate is a non-oxide ceramic.

10. The method of claim 1, wherein the substrate comprises aluminum nitride.

11. The method of claim 1, wherein the substrate comprises beryllium oxide.

12. The method of claim 1, wherein the substrate comprises aluminum oxide.

13. The method of claim 1, wherein the second metal layer comprises copper.

14. The method of claim 1, wherein the first metal layer is a film having a thickness in the range of about 50 nm to about 2.1 μm.

15. The method of claim 1, wherein the second metal layer is a foil having a thickness in the range of about 76 μm to about 305 μm.

16. A bonded metal-ceramic structure comprising: a ceramic substrate;an adhesion-promotion layer bonded to the ceramic substrate; anda metal layer bonded to the adhesion-promotion layer,wherein the adhesion-promotion layer includes a combined oxide of metals in each of the ceramic substrate and the metal layer.

17. The bonded metal-ceramic structure of claim 16, wherein: the metal layer comprises copper;the ceramic substrate comprises aluminum nitride; andthe adhesion-promotion layer comprises copper aluminum oxide.

18. The bonded metal-ceramic structure of claim 16, wherein the ceramic substrate is a non-oxide ceramic.