Microfluidic chip, head, and dispensing device for dispensing fluids containing an acidic component

1. A method of generating a microfluidic ejection chip, comprising:

creating an opening in a silicon substrate through multiple iterations of a deep reactive ion etching process;

forming a passivation layer over any exposed portion of silicon at the opening following each iteration of the deep reactive ion etching of the silicon substrate;

not removing the passivation layer at a conclusion of the etching of the silicon substrate to define a fluid passageway at the opening in the silicon substrate, such that the passivation layer is permanent on the silicon substrate at the opening;

depositing an operational layer including fluid ejection elements on the silicon substrate, a device surface having conductive and insulative features, and a flow feature layer; and

applying a resist layer over the flow feature layer.

2. The method of claim 1 , wherein the fluid passageway is defined by a silicon sidewall of the silicon substrate that is entirely covered by the passivation layer to protect the silicon sidewall from exposure to an acidic fluid.

3. The method of claim 2 , wherein the acidic fluid is a reagent having a content of hydrofluoric acid/nitric acid (HF/HNO 3 ), Ethylenediamine pyrocatechol (EDP), Potassium hydroxide/Isopropyl alcohol (KOH/IPA), or Tetramethylammonium hydroxide (TMAH).

4. The method of claim 1 , wherein the passivation layer is a fluorocarbon layer.

5. The method of claim 1 , wherein the passivation layer is formed at the opening over any exposed portion of silicon using disposition of C 4 F 8 gas.

6. The method of claim 1 , wherein the passivation layer extends continuously around a perimeter of the fluid passageway.