Method of depositing heater material over a photoresist scaffold

1. A method of forming an inkjet printhead with a suspended heater element, the method comprising at least the steps of:

depositing a layer of photoresist on a substrate;

masking the layer of photoresist with a mask that is opaque to light of a predetermined wavelength;

focusing a source of light at the predetermined wavelength on to the mask and the layer of photoresist to cure portions of the layer of photoresist;

etching away uncured photoresist from the layer of photo resist to form a sacrificial photoresist scaffold having sloped side faces; and,

depositing heater material over the sacrificial photoresist scaffold; wherein,

the sloped side faces are formed using a predetermined focusing condition employed by the source of light during exposure of the layer of photoresist.

2. The method of claim 1 , wherein the inkjet printhead has a nozzle corresponding to the suspended heater, the nozzle being supported on a front face of the substrate.

3. The method of claim 2 , wherein the sacrificial photoresist scaffold has a substantially planar upper surface.

4. The method of claim 3 , wherein the upper surface is substantially parallel with the front face of the substrate.

5. The method of claim 1 , wherein the sacrificial photoresist scaffold is substantially disc-shaped.

6. The method of claim 2 , wherein the sacrificial photoresist scaffold is formed, at least partially, over a nozzle inlet plugged with photoresist.

7. The method of claim 1 , wherein at least two electrodes are positioned adjacent the heater element, the electrodes being provided for passing an actuating current through the heater element.

8. The method of claim 7 , wherein the heater material is deposited over the electrodes at the same time as being deposited over the sacrificial photoresist scaffold.

9. The method of claim 8 , wherein the sloped side faces provide increased deposition of heater material between the heater element and the electrodes.

10. The method of claim 1 , wherein the heater material is comprised of TiAlN.

11. The method of claim 1 , wherein the heater element comprises the heater material sandwiched between a lower and an upper passivation films.

12. The method of claim 11 , wherein the passivation films are comprised of a material selected from the group consisting of tantalum, tantalum nitride and silicon nitride.

13. The method of claim 11 , wherein the lower passivation film is deposited onto the sacrificial photoresist scaffold prior to deposition of the heater material.

14. The method of claim 2 , wherein the sloped faces are angled at between 45 and 85° relative to the front face of the substrate.

15. The method of claim 1 , further comprising the steps of:

forming a nozzle chamber for the suspended heater element; and

removing the sacrificial photoresist scaffold.

16. A method of fabricating an inkjet printhead comprising a plurality of suspended heater elements, each suspended heater element being formed by a method according to claim 1 .