Etching a substrate: processes – Forming or treating thermal ink jet article
Reexamination Certificate
1998-07-10
2001-08-14
Gulakowski, Randy (Department: 1746)
Etching a substrate: processes
Forming or treating thermal ink jet article
C347S054000, C347S055000, C347S056000, C347S065000, C438S021000
Reexamination Certificate
active
06274056
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates to the manufacture of ink jet printheads and, in particular, discloses a method of manufacture of a direct firing thermal bend actuator ink jet printer.
BACKGROUND OF THE INVENTION
Many ink jet printing mechanisms are known. Unfortunately, in mass production techniques, the production of ink jet heads is quite difficult. For example, often, the orifice or nozzle plate is constructed separately from the ink supply and ink ejection mechanism and bonded to the mechanism at a later stage (Hewlett-Packard Journal, Vol. 36 no 5, pp 33-37 (1985)). These separate material processing steps required in handling such precision devices often add a substantial expense in manufacturing.
Additionally, side shooting ink jet technologies (U.S. Pat. No. 4,899,181) are often used but again, this limits the amount of mass production throughput given any particular capital investment.
Additionally, more esoteric techniques are also often utilised. These can include electroforming of nickel stage (Hewlett-Packard Journal, Vol. 36 no 5, pp 33-37 (1985)), electro-discharge machining, laser ablation (U.S. Pat. No. 5,208,604), micro-punching, etc.
The utilisation of the above techniques is likely to add substantial expense to the mass production of ink jet printheads and therefore add substantially to their final cost.
It would therefore be desirable if an efficient system for the mass production of ink jet printheads could be developed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an alternative form of actuation of ink drops for an ink jet printhead.
In accordance with a first aspect of the present invention, there is provided a method of manufacturing a direct firing thermal bend actuator ink jet printhead wherein an array of nozzles are formed on a substrate utilising planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.
The printheads can be formed utilising standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably are of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrate.
In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet printhead arrangement including a series of nozzle chambers, the method comprising the steps of: (a) utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon; (b) etching a nozzle chamber aperture in the electrical circuitry layer interconnected with a nozzle chamber in the semiconductor wafer; (c) depositing a first sacrificial layer filling the nozzle chamber; (d) depositing and etching a first expansion layer of material having a high coefficient of thermal expansion over the nozzle chamber; (e) depositing and etching a conductive material layer on the first layer to form a conductive heater element over the first expansion layer, the heater element being conductively interconnected to the electrical circuitry layer; (f) depositing and etching a second expansion layer of material having a high coefficient of thermal expansion over at least the conductive material layer, the etching including etching a leaf portion over the nozzle chamber; (g) back etching the wafer to the epitaxial layer; (h) etching a nozzle aperture in the epitaxial layer; and (i) etching away the sacrificial layers.
The step (c) further can comprise etching the first expansion layer of material so that it has an undulating surface. The step (d) preferably can include retaining the undulating surface in the conductive heater element. The epitaxial layer can be utilized as an etch stop in the step (b) which can comprise a crystallographic etch of the wafer.
The steps are preferably also utilized to simultaneously separate the wafer into separate printheads.
REFERENCES:
patent: 4728392 (1988-03-01), Mlura et al.
patent: 5565113 (1996-10-01), Hadimioglu et al.
patent: 5719604 (1998-02-01), Inui et al.
patent: 5872582 (1999-02-01), Pan
patent: 5897789 (1999-04-01), Weber
patent: 3-247451 (1991-11-01), None
Krause et al., “A micromachined single-chip inkjet printhead”, Senson And Actuators A, vol.A53, p. 405-409, 1996.
Ahmed Shamim
Gulakowski Randy
Silverbrook Research Pty Ltd
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