Semiconductor device manufacturing: process – Manufacture of electrical device controlled printhead
Reexamination Certificate
1998-07-10
2001-10-23
Bowers, Charles (Department: 2823)
Semiconductor device manufacturing: process
Manufacture of electrical device controlled printhead
C347S020000, C347S047000, C347S054000, C347S068000, C216S027000, C216S056000
Reexamination Certificate
active
06306671
ABSTRACT:
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 shape memory alloy 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, pp33-37 (1985)). These separate material processing steps required in handling such precision devices often adds a substantially expense in manufacturing.
Additionally, side shooting ink jet technologies (U.S. Pat. No. 4,899,181) are often used but again, this limit the amount of mass production throughput given any particular capital investment.
Additionally, more esoteric techniques are also often utilized. These can include electroforming of nickel stage (Hewlett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)), electro-discharge machining, laser ablation (U.S. Pat. No. 5,208,604), micro-punching, etc.
The utilization 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 for a new form of ink jet printing device that utilizes a shape memory alloy in its activation method.
In accordance with a first aspect of the present invention, there is provided a method of manufacturing a shape memory alloy printhead wherein an array of nozzles are formed on a substrate utilizing 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 utilizing standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to said 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 on; (b) etching a nozzle chamber in the wafer and the electrical circuitry layer; (c) depositing and etching a layer of sacrificial material, filling the nozzle chamber; (d) depositing and etching a layer of shape memory alloy forming a conductive paddle structure over the nozzle chamber attached to the electrical circuitry layer; (e) back etching the semiconductor wafer to the epitaxial layer; (f) etching the epitaxial layer to define a nozzle ejection hole therein interconnecting with the nozzle chamber; (g) etching away the sacrificial layers.
The step (b) utilizes the epitaxial layer as an etch stop and can comprise a crystallographic etch. The shape memory alloy can comprise substantially nitinol.
The steps are preferably also utilized to simultaneously separate the wafer into separate print heads.
REFERENCES:
patent: 5850241 (1998-12-01), Silverbrook
patent: 6110754 (2000-08-01), Silverbrook
patent: 03202351 A (1991-09-01), None
patent: 406091865A (1994-04-01), None
Bowers Charles
Lee Hsien Ming
Silverbrook Research Pty Ltd
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