Fully integrated thermal inkjet printhead having etched back PSG layer

Described herein is a monolithic printhead formed using integrated circuit techniques. Thin film layers, including ink ejection elements, are formed on a top surface of a silicon substrate. The various layers are etched to provide conductive leads to the ink ejection elements. At least one ink feed hole is formed through the thin film layers for each ink ejection chamber. A trench is etched in the bottom surface of the substrate so that ink can flow into the trench and into each ink ejection chamber through the ink feed holes formed in the thin film layers. An orifice layer is formed on the top surface of the thin film layers to define the nozzles and ink ejection chambers. A phosphosilicate glass (PSG) layer, providing an insulation layer beneath the resistive layers, is etched back from the ink feed holes and is protected by a passivation layer to prevent the ink from interacting with the PSG layer. Other layers may also be protected from the ink by being etched back.

FIELD OF THE INVENTION

This invention relates to inkjet printers and, more particularly, to a monolithic printhead for an inkjet printer.

BACKGROUND

Inkjet printers typically have a printhead mounted on a carriage that scans back and forth across the width of a sheet of paper feeding through the printer. Ink from an ink reservoir, either on-board the carriage or external to the carriage, is fed to ink ejection chambers on the printhead. Each ink ejection chamber contains an ink ejection element, such as a heater resistor or a piezoelectric element, which is independently addressable. Energizing an ink ejection element causes a droplet of ink to be ejected through a nozzle for creating a small dot on the medium. The pattern of dots created forms an image or text.

As dot resolutions (dots per inch) increase along with the firing frequencies, more heat is generated by the firing elements. This heat needs to be dissipated. Heat is dissipated by a combination of the ink being ejected and the printhead substrate sinking heat from the ink ejection elements. The substrate may even be cooled by the supply of ink flowing to the printhead.

Additional information regarding one particular type of printhead and inkjet-printer is found in U.S. Pat. No. 5,648,806, entitled, “Stable Substrate Structure For A Wide Swath Nozzle Array In A High Resolution Inkjet Printer,” by Steven Steinfield et al., assigned to the present assignee and incorporated herein by reference.

As the resolutions and printing speeds of printheads increase to meet the demanding needs of the consumer market, new printhead manufacturing techniques and structures are required. Hence, there is a need for an improved printhead that has at least the following properties: adequately sinks heat from the ink ejection elements at high operating frequencies; provides an adequate refill speed of the ink ejection chambers with minimum blowback; minimizes cross-talk between nearby ink ejection chambers; is tolerant to particles within the ink; provides a high printing resolution; enables precise alignment of the nozzles and ink ejection chambers; provides a precise and predictable drop trajectory; is relatively easy and inexpensive to manufacture; and is reliable.

SUMMARY

Described herein is a monolithic printhead formed using integrated circuit techniques. Thin film layers, including a resistive layer, are formed on a top surface of a silicon substrate. The various layers are etched to provide conductive leads to the heater resistor elements. Piezoelectric elements may be used instead of the resistive elements. An optional thermally conductive layer below the heater resistors sinks heat from the heater resistors and transfers the heat to a combination of the silicon substrate and the ink.

At least one ink feed hole is formed through the thin film layers for each ink ejection chamber.

A trench is etched in the bottom surface of the substrate so that ink can flow into the trench and into each ink ejection chamber through the ink feed holes formed in the thin film layers.

An orifice layer is formed on the top surface of the thin film layers to define the nozzles and ink ejection chambers. In one embodiment, a photodefinable epoxy is used to form the orifice layer.

A phosphosilicate glass (PSG) layer, providing an insulation layer beneath the resistive layer, is etched back from the ink feed holes and is protected by a passivation layer to prevent the ink from interacting with the PSG layer. Other layers may be protected from ink by being etched back in a similiar manner.

Various thin film structures are described as well as various ink feed arrangements and orifice layers.

The resulting fully integrated thermal inkjet printhead can be manufactured to a very precise tolerance since the entire structure is monolithic, meeting the needs for the next generation of printheads.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1is a perspective view of one type of inkjet print cartridge10which may incorporate the printhead structures of the present invention. The print cartridge10ofFIG. 1is the type that contains a substantial quantity of ink within its body12, but another suitable print cartridge may be the type that receives ink from an external ink supply either mounted on the printhead or connected to the printhead via a tube.

The ink is supplied to a printhead14. Printhead14, to be described in detail later, channels the ink into ink ejection chambers, each chamber containing an ink ejection element. Electrical signals are provided to contacts16to individually energize the ink ejection elements to eject a droplet of ink through an associated nozzle18. The structure and operation of conventional print cartridges are very well known.

The present invention relates to the printhead portion of a print cartridge, or a printhead that can be permanently installed in a printer, and, thus, is independent of the ink delivery system that provides ink to the printhead. The invention is also independent of the particular printer into which the printhead is incorporated.

FIG. 2is a cross-sectional view of a portion of the printhead ofFIG. 1taken along line2—2in FIG.1. Although a printhead may have 300 or more nozzles and associated ink ejection chambers, detail of only a single ink ejection chamber need be described in order to understand the invention. It should also be understood by those skilled in the art that many printheads are formed on a single silicon wafer and then separated from one another using conventional techniques.

InFIG. 2, a silicon substrate20has formed on it various thin film layers22, to be described in detail later. The thin film layers22include a resistive layer for forming resistors24. Other thin film layers perform various functions, such as providing electrical insulation from the substrate20, providing a thermally conductive path from the heater resistor elements to the substrate20, and providing electrical conductors to the resistor elements. One electrical conductor25is shown leading to one end of a resistor24. A similar conductor leads to the other end of the resistor24. In an actual embodiment, the resistors and conductors in a chamber would be obscured by overlying layers.

Ink feed holes26are formed completely through the thin film layers22.

An orifice layer28is deposited over the surface of the thin film layers22and etched to form ink ejection chambers30, one chamber per resistor24. A manifold32is also formed in the orifice layer28for providing a common ink channel for a row of ink ejection chambers30. The inside edge of the manifold32is shown by a dashed line33. Nozzles34may be formed by laser ablation using a mask and conventional photolithography techniques.

The silicon substrate20is etched to form a trench36extending along the length of the row of ink feed holes26so that ink38from an ink reservoir may enter the ink feed holes26for supplying ink to the ink ejection chambers30.

In one embodiment, each printhead is approximately one-half inch long and contains two offset rows of nozzles, each row containing 150 nozzles for a total of 300 nozzles per printhead. The printhead can thus print at a single pass resolution of 600 dots per inch (dpi) along the direction of the nozzle rows or print at a greater resolution in multiple passes. Greater resolutions may also be printed along the scan direction of the printhead. Resolutions of 1200 or greater dpi may be obtained using the present invention.

In operation, an electrical signal is provided to heater resistance24, which vaporizes a portion of the ink to form a bubble within an ink ejection chamber30. The bubble propels an ink droplet through an associated nozzle34onto a medium. The ink ejection chamber is then refilled by capillary action.

FIG. 3is a perspective view of the underside of the printhead ofFIG. 2showing trench36and ink feed holes26. In the particular embodiment ofFIG. 3, a single trench36provides access to two rows of ink feed holes26.

In one embodiment, the size of each ink feed hole26is smaller than the size of a nozzle34so that particles in the ink will be filtered by the ink feed holes26and will not clog a nozzle34. The clogging of an ink feed hole26will have little effect on the refill speed of a chamber30since there are multiple ink feed holes26supplying ink to each chamber30. In one embodiment, there are more ink feed holes26than ink ejection chambers30.

FIG. 4is a cross-sectional view along line4—4of FIG.2.FIG. 4shows the individual thin film layers. In the particular embodiment ofFIG. 4, the portion of the silicon substrate20shown is about 10 microns thick. This portion is referred to as the bridge. The bulk silicon is about 675 microns thick.

A field oxide layer40, having a thickness of 1.2 microns, is formed over silicon substrate20using conventional techniques. A phosphosilicate glass (PSG) layer42, having a thickness of 0.5 microns, is then applied over the layer of oxide40.

A boron PSG or boron TEOS (BTEOS) layer may be used instead of layer42but etched in a manner similar to the etching of layer42.

A resistive layer of, for example, tantalum aluminum (TaAl), having a thickness of 0.1 microns, is then formed over the-PSG layer42. Other known resistive layers can also be used. The resistive layer, when etched, forms resistors24. The PSG and oxide layers,42and40, provide electrical insulation between the resistors24and substrate20, provide an etch stop when etching substrate20, and provide a mechanical support for the overhang portion45. The PSG and oxide layers also insulate polysilicon gates of transistors (not shown) used to couple energization signals to the resistors24.

It is difficult to perfectly align the backside mask (for forming trench36) with the ink feed holes26. Thus, the manufacturing process is designed to provide a variable overhang portion45rather than risk having the substrate20interfere with the ink feed holes26.

Not shown inFIG. 4, but shown inFIG. 2, is a patterned metal layer, such as an aluminum-copper alloy, overlying the resistive layer for providing an electrical connection to the resistors. Traces are etched into the AlCu and TaAl to define a first resistor dimension (e.g., a width). A second resistor dimension (e.g., a length) is defined by etching the AlCu layer to cause a resistive portion to be contacted by AlCu traces at two ends. This technique of forming resistors and electrical conductors is well known in the art.

Over the resistors24and AlCu metal layer is formed a silicon nitride (Si3N4) layer46, having a thickness of 0.5 microns. This layer provides insulation and passivation. Prior to the nitride layer46being deposited, the PSG layer42is etched to pull back the PSG layer42from the ink feed hole26so as not to be in contact with any ink. This is important because the PSG layer42is vulnerable to certain inks and the etchant used to form trench36.

Etching back a layer to protect the layer from ink may also apply to the polysilicon and metal layers in the printhead.

Over the nitride layer46is formed a layer48of silicon carbide (SiC), having a thickness of 0.25 microns, to provide additional insulation and passivation. The nitride layer46and carbide layer48now protect the PSG layer42from the ink and etchant. Other dielectric layers may be used instead of nitride and carbide.

The carbide layer48and nitride layer46are etched to expose portions of the AlCu traces for contact to subsequently formed ground lines (out of the field of FIG.4).

On top of the carbide layer48is formed an adhesive layer50of tantalum (Ta), having a thickness of 0.6 microns. The tantalum also functions as a bubble cavitation barrier over the resistor elements. This layer50contacts the AlCu conductive traces through the openings in the nitride/carbide layers.

Gold (not shown) is deposited over the tantalum layer50and etched to form ground lines electrically connected to certain ones of the AlCu traces. Such conductors may be conventional.

The AlCu and gold conductors may be coupled to transistors formed on the substrate surface. Such transistors are described in U.S. Pat. No. 5,648,806, previously mentioned. The conductors may terminate at electrodes along edges of the substrate20.

A flexible circuit (not shown) has conductors which are bonded to the electrodes on the substrate20and terminate in contact pads16(FIG. 1) for electrical connection to the printer.

The ink feed holes26are formed by etching through the thin film layers. In one embodiment, a single feed hole mask is used. In another embodiment, several masking and etching steps are used as the various thin film layers are formed.

The orifice layer28is then deposited and formed, followed by the etching of the trench36. In another embodiment, the trench etch is conducted before the orifice layer fabrication. The orifice layer28may be formed of a spun-on epoxy called SU8. The orifice layer in one embodiment is about 20 microns.

A backside metal may be deposited if necessary to better conduct heat from substrate20to the ink.

FIG. 5is a top-down view of the structure of FIG.2. The dimensions of the elements may be as follows: ink feed holes26are 10 microns×20 microns; ink ejection chambers30are 20 microns×40 microns; nozzles34have a diameter of 16 microns; heater resistors24are 15 microns×15 microns; and manifold32has a width of about 20 microns. The dimensions will vary depending on the ink used, the operating temperature, the printing speed, the desired resolution, and other factors.

FIG. 6is a top-down view of a portion of an alternative embodiment printhead. In this printhead, there is no ink manifold. Ink to each ink ejection chamber is provided by two dedicated ink feed holes. Other views of this printhead are shown inFIGS. 7,8, and9. In the embodiment shown, there are twice as many ink feed holes as heater resistors. In another embodiment, there are one or more dedicated ink feed holes for each chamber.

InFIG. 6, the outline of an ink ejection chamber60is shown along with a heater resistor62, a nozzle64(with the smaller diameter of the nozzle shown in dashed outline), and ink feed holes66and67. Ink feed holes66and67are designed to be smaller than nozzle64so as to filter any particles before reaching chamber60. If a particle clogs one ink feed hole, the size of the other ink feed hole is adequate to refill chamber60at close to the operating frequency.

FIG. 7is a cross-sectional perspective view along line7—7inFIG. 6illustrating a single ink ejection chamber60.

InFIG. 7, a silicon substrate70has formed on it a plurality of thin film layers72(to be identified in FIG.8), including a resistive layer and an AlCu layer that are etched to form the heater resistors62. AlCu conductors63are shown leading to the resistors62.

Ink feed holes67are formed through the thin film layers72to extend to the surface of the silicon substrate70. An orifice layer74is then formed over the thin film layers72to define ink ejection chambers60and nozzles64. The silicon substrate70is etched to form a trench76extending the length of the row of ink ejection chambers. The trench76may be formed prior to the orifice layer. Ink78from an ink reservoir is shown flowing into trench76, through ink feed hole67, and into chamber60.

FIG. 8is a cross-sectional view along line8—8inFIG. 7showing one-half of chamber60. The other half is symmetrical with FIG.8. Unlike the first embodiment, where a portion of the silicon substrate20was located directly beneath the heater resistors to sink heat from the resistors, the structure ofFIG. 8uses a metal layer beneath the heater resistors to draw heat away from the resistors and transfer the heat to the substrate and to the ink itself.

An insulating layer of field oxide90, having a thickness of 1.2 microns, is formed over the silicon substrate70(FIG. 7) prior to the trench76being formed. The portion of the printhead inFIG. 8is shown after the trench76is formed so the substrate70is not shown in the field of view.

A PSG layer92having a thickness of 0.5 microns is then deposited over oxide90. As described with respect toFIG. 4, the oxide and PSG layers provide electrical insulation and thermal conductivity between the heater resistor and the underlying conductive layers, as well as provide increased mechanical support of the bridge extending between the remaining silicon substrate portions after the trench76is etched. Also, as previously mentioned, the PSG layer92is pulled back from the ink feed hole67to prevent contact with the ink which would otherwise react with the PSG.

Formed over the PSG layer92is a resistive layer of tantalum aluminum, having a thickness of 0.1 microns. An AlCu layer (not shown) is formed over the TaAl layer. The TaAl layer and AlCu layer are etched as previously described to form the various heater resistors62and conductors63(FIG.7).

A layer of nitride96, having a thickness of 0.5 microns, is then formed over the resistors62and AlCu conductors, followed by a layer of silicon carbide98, having a thickness of 0.25 microns. The nitride/carbide layers are etched to expose portions of the AlCu conductors.

An adhesive layer100of tantalum, having a thickness of 0.6 microns, is then deposited, followed by a conductive layer of gold. Both layers are then etched to form gold conductors electrically contacting certain AlCu conductors leading to heater resistors62and ultimately terminating in bonding pads along edges of the substrate. In one embodiment, the gold conductors are ground lines.

The ink feed holes67are then etched through the thin film layers (or patterned during fabrication of the thin film layers). The orifice layer74is deposited and etched to form chambers60and nozzles64. Nozzles64may also be formed by laser ablation.

The back side of the substrate70(FIG. 7) is then masked and etched using a TMAH etch to form the trench76, extending the length of a row of ink ejection chambers60. Any one of several etch techniques could be used, wet or dry. Examples of dry etches include XeF2 and SiF6. Examples of appropriate wet etches include Ethylene Diamine Pyrocatechol (EDP), Potassium Hydroxide (KOH), and TMAH. Other etches may also be used. Any one of these or a combination thereof could be used for this application.

The trench76may have a width of approximately one ink ejection chamber or may have a width that encompasses multiple rows of ink ejection chambers. The trench may be formed at any time during the fabrication process.

After the trench76is formed, an adhesion layer101of tantalum (Ta), having a thickness of 0.1 microns, is formed on the back side of the wafer overlying the field oxide90. A heat conducting layer102of, for example, gold (Au), having a thickness of 1.5 microns, is then formed over the adhesion layer101. Another adhesion layer103of tantalum, having a thickness of 0.1 microns, is then formed over the heat conducting layer102.

FIG. 9is a top-down view of one-half of an ink ejection chamber60in the printhead of FIG.6.FIG. 9illustrates the etching of the various layers and is to be taken in conjunction with FIG.8. Starting with the ink feed hole67, the oxide and passivation layers90,96, and98form a shelf approximately 2 microns long. The shelf length could be other sizes, for example, 1-100 microns. The tantalum layer100(used as an adhesive layer for gold conductors) is shown extending 1 micron beyond the PSG layer92, and the PSG layer92is shown extending 2 microns beyond the resistor62.

FIGS. 10A-10Fare cross-sectional views of a portion of the wafer during various steps during the manufacturing of the printhead of FIG.8. Conventional deposition, masking, and etching steps are used unless otherwise noted.

InFIG. 10A, a silicon substrate70with a crystalline orientation of (111) is placed in a vacuum chamber. Field oxide90is grown in a conventional manner. PSG layer92is then deposited using conventional techniques.FIG. 10Ashows mask110being formed over the PSG layer92using conventional photolithographic techniques. The PSG layer92is then etched using conventional Reactive Ion Etching (RIE) to pull back the PSG layer92from the subsequently formed ink feed hole.

InFIG. 10B, mask110is removed and a resistive layer111of TaAl is deposited over the surface of the wafer. A conductive layer112of AlCu is then deposited over the TaAl. A first mask113is deposited and patterned using conventional photolithographic techniques, and the conductive layer112and the resistive layer111are etched using conventional IC fabrication techniques. Another masking and etching step (not shown) is used to remove the portions of the AlCu over the heater resistors62, as previously described. The resulting AlCu conductors are outside the field of view ofFIGS. 10A-10F.

InFIG. 10C, the passivation layers, nitride96and carbide98, are then deposited on the surface of the wafer using conventional techniques. The passivation layers are then masked (outside the field of view) and etched using conventional techniques to expose portions of the AlCu conductive traces for electrical contact to a subsequent gold conductive layer.

An adhesive layer100of tantalum and a conductive layer of gold114are then deposited over the wafer, masked, using a first mask115, and etched, using conventional techniques to form the ground lines, terminating in bond pads along edges of the substrate. A second mask (not shown) removes portions of the gold over the Ta adhesive layer100, such as over the heater resistor area.

FIG. 10Dillustrates the resulting structure, after the steps ofFIG. 10C, having a mask116exposing a portion of the thin film layers to be etched to form the ink feed holes. Alternatively, multiple masking and etching steps may be used as the various thin film layers are formed to etch the ink feed holes.

FIG. 10Eillustrates the structure after etching the thin film layers. The thin film layers are etched using an anisotropic etch. This ink feed etch process can be a combination of several types of etches (RIE or wet). The ink feed holes67could be fabricated with an etch in combination with the films being patterned during fabrication. The holes67could be defined with one mask and etch step or with a series of etches. All the etches may use conventional IC fabrication techniques.

The back side of the wafer is then masked using conventional techniques to expose the ink trench portion76(see FIG.7). The trench76is etched using a wet-etching process using tetramethyl ammonium hydroxide (TMAH) as an etchant to form the angled profile. Other wet anisotropic etchants may also be used. (See U. Schnakenberg et al.,TMAHW Etchants for Silicon Micromachining, Tech Digest, 6th Int. Conf. Solid State Sensors and Actuators (Transducers '91), San Francisco, Calif., Jun. 24-28, 1991, pp. 815-818.) Such a wet etch will form the angled trench76. The trench76may extend the length of the printhead or, to improve the mechanical strength of the printhead, only extend a portion of the length of the printhead beneath the ink ejection chambers60. A passivation layer may be deposited on the substrate if reaction of the substrate with the ink is a concern.

InFIG. 10F, a tantalum adhesive layer101is then flash evaporated or sputtered over the bottom surface of the substrate followed by a gold heat conductive layer102and another tantalum layer103. These layers act as thermally conductive layers and provide mechanical strength to the bridge portion.

FIG. 10Falso shows the formation of the orifice layer74. Orifice layer74, in one embodiment, is a photo-imagible material, such as SU8. Orifice layer74may be laminated, screened, or spun-on. The ink chambers and nozzles are formed through photolithography.

The resulting structure after etching of the orifice layer74is shown in FIG.8. The orifice layer74may also be formed in a two-stage process, with a first layer being formed to define the ink chambers and the second layer being formed to define the nozzles.

The resulting wafer is then sawed to form the individual printheads, and a flexible circuit (not shown) used to provide electrical access to the conductors on the printhead is then connected to the bonding pads at the edges of the substrate. The resulting assembly is then affixed to a plastic print cartridge, such as that shown inFIG. 1, and the printhead is sealed with respect to the print cartridge body to prevent ink seepage.

FIG. 11is a cross-sectional view of a portion of a second alternative embodiment printhead similar to that shown inFIG. 4, except the trench in the silicon is not etched all the way to the thin film. Rather, the bulk silicon120is partially etched to form a thin silicon bridge below the heater resistors24. To accomplish this, before the thin film layers are deposited, the front side of the wafer is patterned with a mask to expose those silicon areas in the trench area which are not to be completely etched through. The exposed portions are then doped with a P-type dopant, such as boron, to an approximate depth of 1 to 2 microns. The depth could be as deep as 15 microns or deeper. The mask is then removed. A backside hardmask is used to define where the trench etch will occur. The back of the wafer is then subjected to a TMAH etch process, which only etches the un-doped silicon portions. Silicon portions in the trench area having a thickness of about 10 microns now underlie the resistors24.

A similar process may be used to form the thin silicon bridge in FIG.4.

Thin film layers identified with the same numbers inFIG. 4may be identical and are subsequently formed using processes similar to those previously described. The orifice layer122may be identical to that shown in FIG.8.

One advantage of the printhead ofFIG. 11is that the silicon below the resistors24conducts heat away from the resistors24.

One skilled in the art of integrated circuit manufacturing would understand the various techniques used to form the printhead structures described herein. The thin film layers and their thicknesses may be varied, and some layers deleted, while still obtaining the benefits of the present invention.

FIG. 12illustrates one embodiment of an inkjet printer130that can incorporate the invention. Numerous other designs of inkjet printers may also be used along with this invention. More detail of an inkjet printer is found in U.S. Pat. No. 5,852,459, to Norman Pawlowski et al., incorporated herein by reference.

Inkjet printer130includes an input tray132containing sheets of paper134which are forwarded through a print zone135, using rollers137, for being printed upon. The paper134is then forwarded to an output tray136. A moveable carriage138holds print cartridges140-143, which respectively print cyan (C), black (K), magenta (M), and yellow (Y) ink.

In one embodiment, inks in replaceable ink cartridges146are supplied to their associated print cartridges via flexible ink tubes148. The print cartridges may also be the type that hold a substantial supply of fluid and may be refillable or non-refillable. In another embodiment, the ink supplies are separate from the printhead portions and are removeably mounted on the printheads in the carriage138.

The carriage138is moved along a scan axis by a conventional belt and pulley system and slides along a slide rod150. In another embodiment, the carriage is stationery, and an array of stationary print cartridges print on a moving sheet of paper.

Printing signals from a conventional external computer (e.g., a PC) are processed by printer130to generate a bitmap of the dots to be printed. The bitmap is then converted into firing signals for the printheads. The position of the carriage138as it traverses back and forth along the scan axis while printing is determined from an optical encoder strip152, detected by a photoelectric element on carriage138, to cause the various ink ejection elements on each print cartridge to be selectively fired at the appropriate time during a carriage scan.

The printhead may use resistive, piezoelectric, or other types of ink ejection elements.

As the print cartridges in carriage138scan across a sheet of paper, the swaths printed by the print cartridges overlap. After one or more scans, the sheet of paper134is shifted in a direction towards the output tray136, and the carriage138resumes scanning.

The present invention is equally applicable to alternative printing systems (not shown) that utilize alternative media and/or printhead moving mechanisms, such as those incorporating grit wheel, roll feed, or drum or vacuum belt technology to support and move the print media relative to the printhead assemblies. With a grit wheel design, a grit wheel and pinch roller move the media back and forth along one axis while a carriage carrying one or more printhead assemblies scans past the media along an orthogonal axis. With a drum printer design, the media is mounted to a rotating drum that is rotated along one axis while a carriage carrying one or more printhead assemblies scans past the media along an orthogonal axis. In either the drum or grit wheel designs, the scanning is typically not done in a back and forth manner as is the case for the system depicted in FIG.12.

Multiple printheads may be formed on a single substrate. Further, an array of printheads may extend across the entire width of a page so that no scanning of the printheads is needed; only the paper is shifted perpendicular to the array.

Additional print cartridges in the carriage may include other colors or fixers.