Patent ID: 7323115

Claim:
A method of manufacturing a substrate for an ink jet recording head, wherein said substrate has a supply port, penetrating said substrate, for supplying liquid and an energy generating element for generating energy for ejecting the liquid, said method comprising: a step of forming a protecting film on a surface of said substrate which is opposite from a surface on which said energy generating element is disposed; a step of etching a surface of said protecting film by liquid containing ammonium fluoride to make said protecting film a thin film having a thickness of not more than 500 nm; a step of forming an etching-resistant film on the thus etched protecting film; a step of forming opening patterns in said protecting film and said etching-resistant film; a step of forming an opening as said supply port, in a side of said substrate opposite from a side thereof having said energy generating element, by etching said substrate through said opening patterns; a step of removing a projected end portion of said protecting film which is projected into said opening and which is produced in said opening forming step; and a step of removing said etching-resistant film after said projected end portion removing step.