Increased threshold uniformity of thermal ink transducers

Details Increased threshold uniformity of thermal ink transducers Increased threshold uniformity of thermal ink transducers

1995-03-07

1997-06-17

Powell, William

Etching a substrate: processes

Forming or treating thermal ink jet article

1566331, 1566571, 216 2, H01L 2100

Patent

active

056393865

ABSTRACT:
The resistors of heater elements are formed by chemical vapor deposition of polycrystalline silicon at at least one of a flat temperature profile of 620.degree. C. and a ramped temperature profile of 620.degree. C. to 640.degree. C. in a first embodiment. Such method of forming the polysilicon result in a predominantly uniform grain size of approximately 1000 .ANG., where grain size can vary between 200 .ANG. to 1000 .ANG.. Alternatively, the resistors are formed by chemical vapor deposition of amorphous polysilicon at at least one of a flat temperature profile at a temperature below 580.degree. C. and a ramped temperature profile of 565.degree. C. to 575.degree. C. In the alternative embodiment, the polysilicon has a grain size of at least 1000 .ANG.. During the ion implantation of either p-type or n-type dopants into the polysilicon, a flood gun located in an ion implanter emits low energy electrons to neutralize the build-up of positive charges on the polysilicon surface. Because the low energy electrons prevent the build-up of electric charges on the surface of the polysilicon, the usual build-up of an electrical field on the surface of the polysilicon is eliminated, and the polysilicon can be uniformly doped by ion implantation of dopants. By using the flood gun during the fabrication of the heater elements of the printhead, the resistors of the heater elements and printheads have substantially uniform sheet resistances relative to each other. The sheet resistances of the resistors in the printhead vary less than 3% and preferably less than 1%. Such low variations in sheet resistance prevent undervoltage and overvoltage from being applied to the resistors and extend the lifetime of the heater element and thus, the printhead.

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A Sedra and K. Smith. "Microelectronic Circuits"; Saunders College Publishing, USA (1991) pp. A4-A6, F1.

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