Diffusion bonded tungsten containing target to titanium or titanium alloy backing plate
A sputtering target assembly comprises a tungsten containing sputtering target, a titanium containing backing plate attached to the tungsten containing sputtering target and an interlayer positioned between and diffusion bonding the tungsten containing sputtering target and the titanium containing backing plate. The interlayer includes a nickel layer immediately adjacent to the tungsten containing sputtering target and a copper layer immediately adjacent to the nickel layer.
1 . A sputtering target assembly comprising:
a tungsten containing sputtering target, wherein the tungsten containing sputtering target comprises 0 wt. % to about 50 wt. % of an alloying component and the balance is tungsten, wherein the alloying component is selected from the group consisting of titanium, aluminum and molybdenum;
a titanium containing backing plate attached to the tungsten containing sputtering target; and
an interlayer positioned between and diffusion bonding the tungsten containing sputtering target and titanium containing backing plate, the interlayer comprising:
a nickel layer immediately adjacent to the tungsten containing sputtering target; and
a copper layer immediately adjacent to the nickel layer, wherein the nickel layer is from 1 micron to 10 microns thick, wherein the copper layer is oxygen-free copper and is about 0.254 mm to 7.62 mm thick, and wherein the sputtering target assembly has a bond strength of at least 10 ksi (68.9 MPa).
2 . The sputtering target assembly of claim 1 wherein the alloying component is titanium and the tungsten containing sputtering target comprises titanium in an amount from about 1 wt. % to about 30 wt. % and the balance is tungsten.
3 . The sputtering target assembly of claim 1 wherein the alloying component is titanium and the tungsten containing sputtering target comprises titanium in an amount from about 3 wt. % to about 15 wt. % and the balance is tungsten.
4 . The sputtering target assembly of claim 1 wherein the tungsten containing sputtering target comprises 100 wt. % tungsten.
5 . The sputtering target assembly of claim 1 wherein the alloying component is aluminum and the tungsten containing sputtering target comprises aluminum in an amount from about 0.1 wt. % to about 5 wt. % and the balance is tungsten.
6 . The sputtering target assembly of claim 1 wherein the alloying component is molybdenum and the tungsten containing sputtering target comprises molybdenum in an amount from about 1 wt. % to about 50 wt. % and the balance is tungsten.
7 . The sputtering target assembly of claim 1 wherein the tungsten containing sputtering target has a purity of at least 3N.
8 . The sputtering target assembly of claim 1 wherein the titanium containing backing plate has a coefficient of thermal expansion (CTE) from about 8.6×10 −6 m/m° C. to about 10×10 −6 m/m° C.
9 . The sputtering target assembly of claim 1 wherein the tungsten containing sputtering target has a coefficient of thermal expansion (CTE) from about 4.5×10 −6 m/m° C. to about 8×10 −6 m/m° C.
10 . The sputtering target assembly of claim 1 wherein a percent bond formed by the interlayer is at least about 98% as determined with C-Scan.
11 . The sputtering target assembly of claim 1 wherein the interlayer consists of the nickel layer and the copper layer.
12 . The sputtering target assembly of claim 1 wherein the bond strength is at least 10 ksi (68.9 MPa) and not more than 30 ksi (207 MPa).
13 . A method for forming a sputtering target assembly, the method comprising:
forming a nickel layer on a back surface of a tungsten containing target, the tungsten containing target comprising 0 wt. % to about 50 wt. % of an alloying component and the balance tungsten, the alloying component is selected from the group consisting of titanium, aluminum, and molybdenum;
forming a copper layer on the nickel layer from oxygen-free copper and hot pressing to bond, the copper layer immediately adjacent to the nickel layer, the copper layer having a thickness of about 0.254 mm to 7.62 mm; and
diffusion bonding the tungsten containing sputtering target to a titanium containing backing plate, wherein the nickel layer is from 1 micron to 10 microns thick and wherein the sputtering target assembly has a bond strength of at least 10 ksi (68.9 MPa).
14 . The method of claim 13 wherein the alloying component is tungsten and the tungsten containing sputtering target comprises titanium in an amount from about 1 wt. % to about 30 wt. % and the balance is tungsten.
15 . The method of claim 13 wherein the tungsten containing sputtering target comprises 100 wt. % tungsten and impurities.
16 . The method of claim 13 wherein the alloying component is molybdenum and the tungsten containing sputtering target comprises molybdenum in an amount from about 1 wt. % to about 50 wt. % and the balance is tungsten.
17 . The method of claim 13 wherein the sputtering target assembly has a percent bond of at least 98% and less than 100%.
18 . The method of claim 13 wherein forming the nickel layer includes forming the nickel layer of less than about 10 microns by electroplating.