Fluid injection head structure and method thereof

1. A method for reinforcing the strength of a fluid injection head structure, comprising the steps of:

providing the fluid injection head structure, comprising:

a substrate;

a manifold formed in the substrate;

at least two rows of chambers in flow communication with the manifold and positioned on two sides of the manifold, wherein fluid flows into the chambers through the manifold; and

at least one bubble generator disposed on the substrate and inside a corresponding chamber; and

forming a conductive trace positioned on a top surface of the substrate for driving the bubble generators, wherein a portion of the conductive trace is positioned between the two rows of chambers and above the manifold.

2. The method of claim 1 wherein further comprising at least one orifice connected to the corresponding chamber such that fluid can flow through the chamber to the orifice.

3. The method of claim 2 wherein the bubble generator comprises a first bubble generator device and a second bubble generator device positioned adjacent to the corresponding orifice of the corresponding chamber, wherein when the chamber is full of fluid, the first bubble generator device generates a first bubble, and the second bubble generator device generates a second bubble to squeeze the fluid inside the chamber out of the orifice.

4. The method of claim 3 wherein the first bubble serves as a virtual valve, restricts flow of fluid out of the chamber.

5. A method for reducing the area required for the circuit layouts on a fluid injection head structure, comprising the steps of:

providing the fluid injection head structure, comprising:

a substrate;

a manifold formed in the substrate;

at least two rows of chambers in flow communication with the manifold and positioned on two sides of the manifold, wherein fluid flows into the chambers through the manifold; and

at least one bubble generator disposed on the substrate and inside a corresponding chamber; and

forming a conductive trace positioned on a top surface of the substrate for driving the bubble generators, wherein a portion of the conductive trace is positioned between the two rows of chambers and above the manifold.

6. The method of claim 5 wherein further comprising at least one orifice connected to the corresponding chamber such that fluid can flow through the chamber to the orifice.

7. The method of claim 6 wherein the bubble generator comprises a first bubble generator device and a second bubble generator device positioned adjacent to the corresponding orifice of the corresponding chamber, wherein when the chamber is full of fluid, the first bubble generator device generates a first bubble, and the second bubble generator device generates a second bubble to squeeze the fluid inside the chamber out of the orifice.

8. The method of claim 7 wherein the first bubble serves as a virtual valve, restricts flow of fluid out of the chamber.

9. A method for manufacturing a reinforced fluid injection head structure, comprising the steps of:

providing a substrate;

forming a field oxide layer on the substrate;

forming an upper layer on the fluid oxide layer;

etching the substrate from the rear to form a manifold in the substrate;

etching the field oxide layer to form at least two rows of chambers in flow communication with the manifold and positioned on two sides of sides of the manifold, wherein fluid flows into the chambers through the manifold;

forming a driving circuit above the manifold and above the upper layer, comprising a conductive trace, wherein a portion of the conductive trace is positioned between the rows of chambers and above the manifold;

forming at least one bubble generator disposed on the substrate; and

forming an orifice connected to the chamber;

wherein the reinforced fluid injection head structure is formed without the need for a separately attached nozzle plate.

10. The method of claim 9 wherein the upper layer is formed of silicon nitride.

11. The method of claim 9 wherein the driving circuit is formed by the steps of:

performing a blanket boron implantation process on the field oxide layer;

forming a poly-silicon gate in the field oxide layer;

forming poly-silicon lines on two edges of the chip;

performing an arsenic implantation to form a source and a drain on both sides of the poly-silicon gate; and

coupling the bubble generator to the poly-silicon lines.

12. The method of claim 9 wherein the bubble generator comprises a first heater and a second heater, wherein the first heater and second heater are connected in series, and wherein the first heater and second generate two bubbles in turn.

13. The method of claim 9 wherein the driving circuit comprises a MOSFET.