wall layer 112 is next patterned and etched to form the nozzle bore 42 for the ejection of ink the etch process also opens up a through hole 116 in the chamber wall as well as in the upper actuator layer 106 so that electrical contact can be made to the lower actuator layer 104 which in turn activates the thermally actuated valve 50 in fig1 the back side of the silicon substrate 82 is then patterned and ink feed channels 30 are etched into the silicon substrate 10 until they meet the liner oxide 94 coating the bottoms of the wells 90 and 92 the first sacrificial layer 100 a and second sacrificial layer 110 are then removed through the nozzle bore 42 with plasma etchants which do not attack the chamber wall layer 112 this step will create the ink staging chamber 40 clear away the sacrificial layer from wells 90 and 92 and release the thermal actuator 50 fig 2 comprised of lower actuator layer 104 and upper actuator layer 106 for polyimide sacrificial layers an oxygen plasma is used for polysilicon sacrificial layers xef 2 xenon difluoride or sf 6 sulfur hexafluoride is used finally the liner oxide 94 coating the bottoms of the wells 90 and 92 is removed by etching from the back of the silicon substrate 10 thereby creating the primary and secondary ink delivery channels 44 and 46 fig1 once the thermal valve actuator is released upon removal of the sacrificial layers the bottom layer 104 of the actuator will be in a state of tensile stress that will cause the actuator to bend towards the opening of the secondary ink delivery channel thereby minimizing any leakage while the actuator is in the.