Micro-fluid ejection device having high resistance heater film
View Patent ↗A semiconductor substrate for a micro-fluid ejection head. The substrate includes a plurality of fluid ejection actuators disposed on the substrate. Each of the fluid ejection actuators includes a thin heater stack comprising a thin film heater and one or more protective layers adjacent the heater. The thin film heater is made of a tantalum-aluminum-nitride thin film material having a nano-crystalline structure consisting essentially of AlN, TaN, and TaAl alloys, and has a sheet resistance ranging from about 30 to about 100 ohms per square. The thin film material contains from about 30 to about 70 atomic % tantalum, from about 10 to about 40 atomic % aluminum and from about 5 to about 30 atomic % nitrogen.
1. A substrate for a micro-fluid ejection head, the substrate comprising a plurality of fluid ejection actuators disposed on the substrate, each of the fluid ejection actuators including a thin heater stack comprising a thin film heater and one or more protective layers adjacent the heater, wherein the thin film heater is comprised of a tantalum-aluminum-nitride thin film material having a nano-crystalline structure consisting essentially of AlN, TaN, and TaAl alloys, and the thin film material having a sheet resistance ranging from about 30 to about 100 ohms per square, and containing from about 30 to about 70 atomic % tantalum, from about 10 to about 40 atomic % aluminum and from about 5 to about 30 atomic % nitrogen.
2. The substrate of claim 1 wherein the thin film heater comprises a thin film layer made by a process of reactive sputtering a tantalum-aluminum alloy target in a nitrogen containing atmosphere on a substrate heated to a temperature ranging from about 100° to about 350° C.
3. The substrate of claim 2 wherein at least one of the protective layers comprises a diamond-like-carbon material.
4. The substrate of claim 3 wherein the diamond-like-carbon layer has a thickness ranging from about 1000 to about 8000 Angstroms.
5. The substrate of claim 2 wherein the thin film heater has a thickness ranging from about 300 to about 3000 Angstroms.
6. The substrate of claim 3 further comprising a cavitation layer as an ink contact surface, wherein the cavitation layer has a thickness ranging from about 1000 to about 6000 Angstroms.
7. The substrate of claim 6 further comprising an adhesion layer disposed between the cavitation layer and the diamond-like-carbon layer, the adhesion layer having a thickness ranging from about 400 to about 600 Angstroms.
8. The substrate of claim 7 wherein the adhesion layer is comprised of a material selected from silicon nitride and tantalum nitride.
9. The substrate of claim 1 further comprising a plurality of drive transistors for driving the plurality of fluid ejection actuators, the drive transistors having an active area width ranging from about 100 to less than about 400 microns.
10. An ink jet printer containing the substrate of claim 1 .
11. The ink jet printer of claim 10 wherein the micro-fluid ejection head contains a high density of thin film heaters ranging from about 6 to about 20 thin film heaters per square millimeter.