Sputtering targets and devices including Mo, Nb, and Ta, and methods
Sputtering targets including molybdenum, niobium and tantalum are found to be useful for sputtering films for electronic devices. Sputtering targets with about 88 to 97 weight percent molybdenum show improved performance, particularly with respect to etching, such as when simultaneously etching an alloy layer including the Mo, Nb, and Ta, and a metal layer (e.g., an aluminum layer). The targets are particularly useful in manufacturing touch screen devices.
1. A method of fabricating an electronic device, the method comprising:
sputtering a sputtering target to form an alloy layer over a substrate, wherein (a) the sputtering target comprises (i) about 88 atomic percent to about 97 atomic percent molybdenum, (ii) about 2 atomic percent to about 8 atomic percent niobium, and (iii) about 0.5 atomic percent to about 5 atomic percent tantalum, and (b) the alloy layer comprises molybdenum, niobium, and tantalum;
forming a metal layer over the alloy layer, wherein the metal layer comprises at least one of Al, Fe, Cu, Ag, Au, W, Zn, Pt, or Sn;
after forming the metal layer, sputtering the sputtering target in a presence of oxygen to form an oxide layer over the alloy layer and the metal layer, wherein the oxide layer comprises molybdenum, niobium, tantalum, and oxygen, and wherein the alloy layer and the oxide layer have the same atomic ratio of Mo:Ta, Nb:Ta, and Mo:Nb; and
with a PAN etchant comprising phosphoric acid, acetic acid, nitric acid, and water, etching away portions of the alloy layer, the metal layer, and the oxide layer.
2. The method of claim 1 , wherein the sputtering target comprises about 0.7 atomic percent to about 4 atomic percent tantalum.
3. The method of claim 1 , wherein the sputtering target comprises about 89 atomic percent to about 96 atomic percent molybdenum.
4. The method of claim 1 , wherein the sputtering target comprises about 2.8 atomic percent to about 7.6 atomic percent niobium.
5. The method of claim 1 , wherein the sputtering target comprises about 0.7 atomic percent to about 3.7 atomic percent tantalum.
6. The method of claim 1 , wherein the total concentration of the molybdenum, the niobium, and tantalum atoms in the sputtering target is about 95 atomic percent or more.
7. The method of claim 1 , wherein the total concentration of the molybdenum, the niobium, and tantalum atoms in the sputtering target is about 99.8 atomic percent or more.
8. The method of claim 1 , wherein the metal layer comprises Al.
9. The method of claim 1 , wherein the substrate comprises glass or silicon.
10. The method of claim 1 , wherein etching away the portion of the oxide layer and the portion of the alloy layer thereunder comprises etching away the portion of the oxide layer and the portion of the alloy layer thereunder with the PAN etchant in a single etch step.
11. The method of claim 1 , further comprising:
forming an input component over the substrate, the input component comprising a plurality of touch sensors; and
forming a transparent cover over the input component.