TWI492851B - Printhead integrated comprising through-silicon connectors - Google Patents

Description

Integrated printhead with through-silicon connectors

This invention relates to printers, and more particularly to inkjet printers. SUMMARY OF THE INVENTION The present invention is primarily directed to providing an improved printhead integrated circuit for ease of servicing of the printhead.

The applicant of the present application has previously demonstrated that a pagewidth inkjet printhead can be formed using a plurality of printhead integrated circuits ('wafers') that are tightly connected along the width of a page at the head end. Arrange by. Although the configuration of the print head integrated circuit has many advantages (eg, minimizing the width of a print area in the paper feed direction), each print head integrated circuit must still be connected to other print head circuits. These print head circuits provide circuits and data to each of the print head integrated circuits.

The applicant of the present application has so far described how a stack of integrated circuit circuits can be connected to an external power by wirebonding the bond pads on each of the printed head integrated circuits to a flexible PCB. /Information supply (see U.S. Patent No. 7,441,865). However, wire bonding protrudes from the ink ejection face of the print head, thus having an adverse effect on both print maintenance and print quality.

Providing a printhead assembly wherein the printhead integrated circuit can be connected to an external circuit/data supply market without these connections that would affect print repair and/or print quality.

Accordingly, in a first aspect, an ink jet print head assembly includes: an ink supply manifold; one or more print head integrated circuits, each of the print head integrated circuits having a front side including the a drive circuit and a plurality of inkjet nozzle assemblies, a back side attached to the ink supply manifold, and at least one ink supply conduit for providing fluid communication between the back side and the inkjet nozzle assemblies; and at least A connector film is used to supply power to the drive circuit, wherein a connector end of the connector film is sandwiched between at least a portion of the ink supply manifold and the one or more print head integrated circuits.

The ink jet printhead assembly according to the invention advantageously provides a convenient mechanism for attaching the printhead integrated circuit to an ink supply manifold while providing electrical connection to the printhead. Furthermore, the front side of the printhead is completely flat over its entire range.

Optionally, the connector film comprises a flexible polymer film having a plurality of conductive traces.

Optionally, the connector film is a tape automated bonding (TAB) film.

Optionally, the back side has a recessed portion for receiving the connector film.

Optionally, the recessed portion is defined along a longitudinally long edge region of each of the print head integrated circuits.

Optionally, a plurality of through silicon connectors provide an electrical connection between the drive circuit and the connection end of the connector film.

Optionally, each of the through connectors extends linearly from the front side toward the back side.

Optionally, each of the through connectors is tapered toward the back side.

Optionally, each through connector is constructed of copper.

Optionally, each of the print head integrated circuits comprises: a substrate; at least one CMOS layer comprising the drive circuit; and a MEMS layer comprising the inkjet nozzle assemblies, wherein the CMOS layer is disposed Between the substrate and the MEMS layer.

Optionally, each through connector extends linearly from a contact pad in the MEMS layer through the COMS layer toward the back side, the contact pad being electrically connected to the CMOS layer.

Optionally, the printhead assembly includes one or more conductor posts that extend linearly between the contact pad and the CMOS layer.

Optionally, each through connector is electrically isolated from the CMOS layer.

Optionally, each through connector has an outer sidewall that includes an insulating film.

Optionally, the outer sidewalls include a diffusion barrier layer between the insulating film and a conductive core of the via through connector.

Optionally, each through connector is soldered to the connection end of the film.

Optionally, the film is bonded to the ink supply manifold along with the plurality of printhead integrated circuits.

Optionally, the plurality of printhead integrated circuits are disposed in end-to-end abutment to provide a one-page wide printhead assembly.

Optionally, a front side surface of the printhead is flat and has no wire bond connections.

Optionally, the front side surface is coated with a layer of hydrophobic polymer (e.g., PDMS).

In a second aspect, a printhead integrated circuit is provided having: a front side including the drive circuit and a plurality of ink jet nozzle assemblies; a back side attached to the ink supply manifold; At least one ink supply conduit for providing fluid communication between the back side and the inkjet nozzle assemblies, wherein the back side has a concave portion for receiving at least a portion of a connector film, the connector film supplying electricity To the drive circuit.

Optionally, a connector end of the connector film is sandwiched between at least a portion of the ink supply manifold and the printhead integrated circuit when the back side is attached to the ink supply manifold.

Optionally, the recessed portion is defined along a longitudinally long edge region of each of the print head integrated circuits.

Optionally, the recessed portion includes a plurality of integrated circuit contacts, each integrated circuit being coupled to the drive circuit.

Optionally, the connector film is a tape automated bonding (TAB) film, and wherein the integrated circuit contacts are disposed to connect to corresponding contacts of the TAB film.

Optionally, a plurality of through silicon connectors extend linearly from the front side toward the back side, and each of the through connectors provides a connection between the driving circuit and a corresponding integrated circuit contact. connection.

Optionally, each integrated circuit contact is defined by one end of another through connector.

Optionally, the back side has a plurality of ink supply conduits extending longitudinally along the printhead integrated circuit, each ink supply conduit defining one or more ink inlets for receiving from the ink supply manifold Ink. Optionally, each ink supply conduit supplies ink to a plurality of front side inlets. Optionally, each front side inlet supplies ink to one or more inkjet nozzle assemblies.

Optionally, each ink supply conduit has a depth that corresponds to the depth of the recessed portion.

In a third aspect, a printhead integrated circuit is provided comprising: a stack of substrates defining a front side and a back side; a plurality of ink jet nozzle assemblies disposed on the front side; a drive circuit, Providing power to the inkjet nozzle assemblies; and one or more through-connectors extending from the front side to the back side, the peer-through connectors providing one or more corresponding to the drive circuit Electrical connections between the integrated circuit contacts, wherein the integrated circuit contacts are configured to connect to a connector film mounted on the back side to supply power to the drive circuit.

Optionally, each integrated circuit contact is defined by one end of another through connector.

In a fourth aspect, a method of making an ink jet printhead assembly having a backside electrical connection is provided, the method comprising the steps of: providing one or more printhead integrated circuits, each print head The integrated circuit has a front side comprising a drive circuit and a plurality of ink jet nozzle assemblies, a back side having one or more ink inlets and a concave edge portion, and one or more connectors extending through the product a body circuit, each connector having a head connected to the driving circuit and a base in the recessed edging portion; placing a connector end of a connector film in the print head integrated circuit In the recessed edge portion of at least one of the plurality, each of the conductive traces has a respective film contact at the connection end; each film is coupled to a base of a corresponding connector; and each print is printed The back side of the header circuit is attached to an ink supply manifold along with the connector film to provide an ink jet printhead assembly having a backside electrical connection.

Optionally, the attaching step sandwiches the connection end of the connector film between a portion of the ink supply manifold and the one or more print head integrated circuits.

Optionally, the connector film is a tape automated bonding (TAB) film.

Optionally, the attaching step includes soldering each film joint to the base of its corresponding connector.

Optionally, the attachment step is carried out using an adhesive film.

Optionally, the adhesive film has a plurality of ink supply holes defined therein.

Optionally, the attaching step includes aligning each of the column head integrated circuits with the adhesive film such that each ink supply hole is aligned with an ink inlet, and the print head integrated circuit is bonded to the adhesive film One side, and an opposite side of the adhesive film is bonded to the ink supply manifold.

Optionally, in this joining step, each of the print head integrated circuits is connected to a separate connector film.

Optionally, in the connecting step, a plurality of print head integrated circuits are connected to the same connector film.

Optionally, the plurality of printhead integrated circuits are attached to the ink supply manifold in an end-on-end abutment for providing a one-page wide printhead assembly.

In a fifth aspect, a method of fabricating a printhead integrated circuit for backside electrical connection is provided, the method comprising the steps of: providing a wafer comprising a plurality of front sides of the wafer a partially fabricated nozzle assembly and one or more through-connectors extending from a front side of the wafer toward a back side; depositing a conductive layer on the front side of the wafer and etching the conductive layer for simultaneously Forming an actuator for each nozzle assembly and a front side contact pad on the head of each of the through connectors, the front side contact pad connecting the turns through connector to the drive circuit in the wafer; implementing further a MEMS processing step for completing the nozzle assembly, and forming an ink supply conduit for the nozzle assembly and the through connector; and dividing the wafer into a plurality of independent print head integrated circuits, each column The head integrated circuit is constructed to be coupled to the drive circuit through the through connector and the back side of the contact pad.

Optionally, the conductive material is selected from the group consisting of titanium nitride, titanium aluminum nitride, titanium, aluminum, and vanadium aluminum alloy.

Optionally, the actuator is selected from the group consisting of: a thermal bubble forming actuator and a thermal bending actuator.

Optionally, the further MEMS processing steps include depositing a substance on the contact pad to seal or wrap the contact pad.

Optionally, the further MEMS processing steps include etching the back side of the wafer to define the ink supply track and a backside recessed portion for each of the print head integrated circuits.

Optionally, the ink supply conduits and the backside recessed portions have the same depth.

Optionally, the back side etch exposes one leg of each of the through connectors in the recessed portion of the back side, each leg including an integrated circuit contact.

Optionally, the through connectors are disposed along a longitudinal edge region of each of the print head integrated circuits, and the back side concave portions extend along the longitudinal edge regions.

Optionally, the integrated circuit contacts are arranged to connect to corresponding contacts of a TAB film.

Optionally, a CMOS layer includes the driver circuit, and the nozzle assemblies are disposed in a MEMS layer formed on the CMOS layer.

Optionally, one or more conductor posts extend linearly between the contact pad and the CMOS layer and/or between the actuator and the CMOS layer.

Optionally, the conductor posts are formed prior to depositing the conductive layer.

Optionally, the conductor posts are formed simultaneously with the weir through connectors.

Optionally, the conductor posts and the meandering through connectors are formed by depositing a conductive material in a predefined via.

Optionally, the conductive material is deposited by electroless plating.

Optionally, each of the predefined through holes has a diameter that is proportional to a depth such that all of the through holes are uniformly filled with deposits.

Optionally, the conductive material is copper.

Optionally, the further MEMS processing steps comprise coating a front side surface with a layer of hydrophobic polymer.

Optionally, the hydrophobic polymer layer is composed of PDMS.

Optionally, the further MEMS processing steps include oxidative removal of the sacrificial material.

To date, applicants of the present invention have described a printhead integrated circuit (or "wafer") 100 that defines a one-page wide printhead in an end-on-end manner. 1 shows a front side surface of a portion of a row of print head ICs 100 in a perspective view, and FIG. 2 shows a pair of print head ICs that are close together.

Each of the print head ICs 100 contains thousands of nozzles arranged in a row. As shown in Figures 1 and 2, the printhead IC 100 is constructed to accept and print five different colored inks (e.g., CMYK and IR (infrared); CCMMY; or CMYKK). Each color conduit 104 of the printhead IC 100 is vertically aligned in the paper feed direction for performing dot-on-dot printing with high resolution (e.g., 1600 dpi). The horizontal distance ('pitch') between two adjacent nozzles 102 in a single column is about 32 microns, and the vertical distance between the two nozzles is based on the firing order of the nozzles; however these columns are typically separated A true number of dotted lines (eg, 10 points line). A more detailed description of the nozzle array configuration and the nozzle emission can be found in U.S. Patent No. 7,438,371, the disclosure of which is incorporated herein by reference.

A single printhead IC 100 typically has a length of about 20 to 22 mm. Therefore, in order to print an A4/US letter size paper, 11 or 12 print head ICs 100 need to be continuously joined together. The number of print head ICs 100 can be varied to suit other widths of paper. For example, a 4 inch photo printer typically uses 5 print head ICs that are joined together.

The printhead IC 100 can be joined together in a variety of ways. A special method for connecting the printhead IC 100 is shown in FIG. In this configuration, the ends of the IC 100 are shaped to be joined together and form a horizontal line of an IC with a vertical offset between adjacent ICs. A tilt joint 106 having a 45 degree angle is disposed between the print head ICs. The joint edge has a serrated profile to facilitate positioning of the adjacent printhead IC.

It is clear from FIGS. 1 and 2 that the leftmost ink supply nozzle 102 of each column is lowered by a pitch of 10 lines and arranged in a triangular configuration. This configuration also ensures that more germanium is provided at the edge of each of the printhead ICs 100 to ensure adequate connections between adjacent ICs. The nozzles contained in each of the descending columns must be fired at different times to ensure that the nozzles in the same column are fired onto the same line on a sheet of paper. Although the control of the operation of the nozzle is performed by a row of print head controller ("SoPEC") devices, the compensation for the descending nozzle train can be performed by a CMOS circuit in the print head, or can be performed by the print head Shared with both SoPEC devices. A complete description of the lowered nozzle configuration and its control can be found in U.S. Patent No. 7,275,805, the disclosure of which is incorporated herein by reference.

Referring now to Figure 3, an opposite backside surface of the printhead integrated circuit 100 is shown. An ink supply conduit 110 is defined in the back side of the printhead IC 100 that extends lengthwise along the length of the printhead IC. These longitudinally directed ink supply conduits 110 meet the nozzle inlet 112 and are in fluid communication with the nozzles 102 located on the front side. Figure 4 shows a portion of a row of printhead ICs that feed ink directly into the ink chamber. Figure 5 shows a portion of another printhead IC that is fed into an ink conduit 114 that extends lengthwise through each column of nozzle chambers. In this alternative configuration, the nozzle chambers receive ink from their adjacent ink conduits through a sidewall inlet.

Turning back to Figure 3, the longitudinally extending ink supply conduits 110 are separated into conduit segments by a bridge or wall 116. These walls 116 provide additional mechanical strength of the printhead IC 100 in the transverse direction relative to the lengthwise conduits 110.

The ink is supplied to the back side of each of the print head ICs via an ink supply manifold in the form of a two-part LCP mold. Referring to Figures 6 through 9, a printhead assembly 130 including a printhead IC 100 is shown attached to the ink supply manifold through an adhesive film.

The ink supply manifold includes a primary LCP mold 122 and an LCP tube mold 124 whose bottom side is sealed. The print head ICs 100 are bonded to the bottom side of the pipe mold 124 by the bonded IC attachment film 120. The LCP pipe mold 124 includes an LCP main pipe 126 that is coupled to an ink inlet 127 and an ink outlet 128 in the main LPC mold 122. The ink inlets 127 and ink outlets 128 are in fluid communication with an ink reservoir and an ink supply system (not shown) that supplies ink to the printhead at a predetermined hydrostatic pressure.

The primary LPC mold 122 has a plurality of air pockets 129 that communicate with the LCP main conduit 126 defined in the LPC conduit mold 124. The air pockets 129 are used to relieve pressure pulses in the ink supply system.

At the base of each LCP main conduit 126, a series of ink supply passages 132 are passed to the printhead ICs 100. The male film 120 has a series of laser drilled supply holes 134 such that the back side of each of the print head ICs 100 is in fluid communication with the ink supply path 132.

Referring now to Figure 10, the ink supply passages 132 are arranged in five columns. The ink supply path 132 of the middle row supplies the ink directly to the back side of the print head IC 100 via the drilled supply hole 134, and the outer ink supply path 132 supplies the ink to the column through the micro-molded path 135. In the printhead IC, each micromolded passage terminates in one of the holes 134 of the laser drilled holes.

Figure 11 shows in more detail how the ink is fed to the backside ink supply conduit 110 of the printhead IC 100. Each laser drilled hole 134 (which is defined in the adhesive film 120) is aligned with a corresponding ink supply conduit 110. In general, the laser drilled aperture 134 is aligned with one of the conduits 110 across the wall 116 such that ink is supplied to a conduit section on either side of the wall 116. This configuration can reduce the amount of fluid connections required between the ink supply manifold and the printhead IC 100.

In order to be helpful in the proper positioning of the ICs 100, a reference point 103A is provided on the surface of the IC 100 (see Figs. 1 and 11). The reference points 103A are in the form of indicia that can be easily identified by an appropriate positioning device to indicate the true location of the IC 100 associated with the original neighboring IC. The adhesive film 120 has complementary reference points 103B that facilitate each of the print head ICs 100 in relation to the alignment of the adhesive film during bonding of the print head ICs to the ink supply manifold. The reference points 103A and 103B are strategically disposed at the edge of the IC 100 and along the length of the bonded IC-attached film 120.

Data and power should be applied to the print head integrated circuit

Returning now to Figure 1, the printhead IC 100 has a plurality of bond pads 105 that extend across the longitudinal edges of the column head IC. The bond pads 105 provide a mechanism for receiving data and/or circuitry from the printhead controller ("SoPEC") device for controlling the operation of the ink jet nozzles 102.

The bond pads 105 are connected to an upper CMOS layer of the printhead IC 100. As shown in Figures 4 and 5, each MEMS nozzle assembly is formed on a CMOS layer 113 that contains the logic and drive circuitry required to emit each nozzle.

Referring to FIGS. 6 through 9, a flexible PCB 140 is wire bonded to the bond pad 105 of the printhead IC 100. The wire bonds are sealed and protected with a wire bond sealant 142 (see Figure 7), which is typically a polymeric resin. The LCP mold 122 includes a curved support wing 123 that is folded and secured around the support wing. The support wing 123 has a plurality of openings 125 for receiving various electronic components 144 of the flexible PCB. In this manner, the flexible PCB 140 can be bent around the outer surface of the printhead assembly 130. A paper guide 148 is mounted on the opposite side of the LPC mold 122 relative to the flexible PCB 140 and completes the printhead assembly 130.

The printhead assembly 130 is designed as part of a user replaceable printhead cartridge that can be removed from the inkjet printer 160 (see Figure 12) and replaced. Thus, the flexible PCB 140 has a plurality of contacts that allow power and data to be connected to electronic components within the printer body, including the SoPEC device.

Because the flexible PCB 140 is wire bonded to the bond pads 105 on each of the printhead ICs 100, the printhead inevitably has a flat longitudinal edge region in the vicinity of the pads. This is clearly shown in Figure 13, which shows a wire bond 150 extending from a bond pad 105 of a row of printhead ICs 100, the printhead IC comprising a plurality of ink jet nozzle assemblies 101. In the structure shown in FIG. 13, the bond pad 105 is formed as a MEMS layer and is connected to the underlying CMOS 113 through the connector post 152. Alternatively, the bond pad 105 can be an exposed upper layer of the CMOS 113 without any other connection lines connected to the MEMS layer. Regardless of the configuration, the wire bond points extend from an ink exit surface 154 of the printhead and are coupled to the flexible PCB 140.

Wire bonding to the bond pad 105 of the printhead IC 100 has several disadvantages, primarily because a major lengthwise region of the printhead IC has wire bond pads 150 (and wire bond sealant 142) from the ink. The exit surface 154 protrudes. The non-planarity of the ink exit surface 154 can result in poorly performing print head maintenance. For example, a wiper cannot sweep across the entire width of the ink exit surface 154 because the wire bond sealant 142 is in the sweep path of the wiper in the sweep direction upstream or downstream of the nozzles. .

Another disadvantage of wire bond tabs is that the entire printhead cannot be coated with a water repellent coating such as PDMS. Applicants have found that PDMS coatings can significantly improve print quality and printhead maintenance (see, for example, U.S. Patent Application Serial No. US 2008/0225076, the disclosure of which is incorporated herein by reference) A completely flat ink jet surface will further improve the effectiveness of this coating.

Print head integrated circuit for back side electrical connection

In view of the above-discussed shortcomings of wire bonding to the printhead IC 100, the applicant has developed a printhead IC2 that uses a backside electrical connection and thus has a completely flat ink exit surface.

Referring to Figure 14, the printhead IC2 is mounted to the LCP pipe mold 124 of the ink supply manifold using an adhesive film 120. The printhead IC2 has at least one elongated ink supply conduit 110 that provides fluid communication between the ink supply manifold and the nozzle assemblies through the nozzle inlet 112 and the ink conduit 114. Thus, the printhead assembly 60 (which includes the printhead IC2) has the same fluid configuration as the printhead assembly 130 described above with reference to Figures 1 through 11 (which includes the printhead IC 100).

However, the print head IC2 is substantially different from the print head IC 100 in the electrical connection to its CMOS circuit layer 113. Significantly, the print head IC2 does not have any front side wire bonding points on its longitudinal edge region 4. Conversely, the print head IC2 has a back side recess 6 at its longitudinal edge which accommodates a TAB (Tape Automated Bonding) film 8. The TAB film 8 is typically a flexible polymer film (eg, Mylar) The film) comprises a plurality of conductive traces that terminate at corresponding film contacts 10 at a connector end of the TAB film. The TAB film 8 is disposed flush with the backside surface 12 of the printhead IC2 such that the TAB film can be bonded to the LCP pipe mold 124 together with the printhead IC2. The TAB film 8 can be connected to the flexible PCB 140; the TAB film can be integrated with the flexible PCB 140. Alternatively, the TAB film 8 can be attached to the printer electronics using other wiring configurations familiar to those skilled in the art.

The print head IC2 has a plurality of through-holes extending from the front side surface of the print head IC to the elongated concave edge portion 6 (which accommodates the TAB film 8). Each of the through holes is filled with a conductor (e.g., copper) to define a through connector 14 that provides electrical connection to the TAB film 8. Each film joint 10 can be attached to the foot or base 15 of the through connector 14 by the use of a suitable connection (e.g., solder ball 16).

The through connector 14 extends through and through a substrate 20 of the printhead IC2. The through connector 14 is isolated from the crucible substrate 20 by insulating sidewalls 21. The insulating sidewalls 21 can be formed of any insulating material compatible with the MEMS process, such as amorphous germanium, polysilicon, or hafnium oxide. The insulating sidewalls 21 can be single or multi-layered sidewalls. For example, the insulating sidewalls 21 may comprise an outer Si or SiO ₂ layer and an inner germanium layer. The inner layer can also serve as a seed layer for electron deposition of copper during fabrication of the tantalum through connector 14.

As shown in FIG. 14, the head 22 of the through connector 14 is in contact with a contact pad 24 defined in a MEMS layer 26 of the printhead IC2. The MEMS layer 26 is disposed on the CMOS circuit layer 113 of the printhead IC2 and includes all of the inkjet nozzle assemblies formed by the MEMS processing steps.

In the example of the hot-bending actuated print head of the Applicant of the present application (for example, the hot-bend actuated print head described in US Patent Application No. US 2008/0129793, the contents of which are hereby incorporated by reference And herein, a conductive thermoelastic actuator 25 can define the roof of each nozzle chamber 101. Thus, the contact pad 24 can be formed simultaneously with the thermoelastic actuator 25 during MEMS fabrication and can be formed from the same material as it. For example, the contact pad 24 can be formed of a thermoelastic material such as a vanadium aluminum alloy, titanium nitride, titanium aluminum nitride, or the like.

However, it will be appreciated that the formation of the contact pads 24 can be incorporated into any step of MEMS fabrication and can comprise any suitable electrically conductive material such as copper, titanium, aluminum, titanium nitride, titanium aluminum nitride. and many more.

The contact pad 24 is connected to the upper layer of the CMOS layer 113 through the copper conductor post 30, the copper conductor post extending from the contact pad toward the CMOS circuit. Thus, conductor post 30 provides an electrical connection between the TAB film 8 and the CMOS circuitry.

Although the structure of the contact pads 24 and the conductor posts 30 in FIG. 14 and the MEMS process used by the applicant to form a thermally curved actuated ink jet nozzle, as described in US Patent Application No. US 12/323,471 The content of the present disclosure is hereby incorporated by reference herein, but the present invention still incorporates other structures that provide a similar backside electrical connection from the backside TAM film 8 to the CMOS layer 113.

For example, referring to FIG. 15, the through connector 14 can terminate at the passive layer 27 above the CMOS layer 113. An embedded contact pad 23 connects the via connector 14 to the upper CMOS by depositing a suitable conductive material on the head of the through connector and an upper CMOS layer exposed through a passive layer 27. Floor. During the fabrication of the MEMS nozzle, after depositing the photoresist 31 and a top layer 37 (eg, tantalum nitride, tantalum oxide, etc.), the MEMS nozzle fabrication provides a completely flat nozzle plate and ink exit surface for the print head . Moreover, the embedded radiation contact pads 23 are completely sealed by the photoresist 31 and covered under the top layer 37. The construction of the contact pad is compatible with the MEMS process used by the Applicant's applicant to make a thermal bubble forming inkjet nozzle assembly, as described in U.S. Patent Nos. 6,755,509 and 7,303,930, the contents of which are incorporated by reference. This reference is hereby incorporated by reference. The nozzle assembly shown in Fig. 15 is a thermal bubble forming ink jet nozzle assembly that includes a suspended heater element 28 and a nozzle opening 102 as described in U.S. Patent No. 6,755,509. It will be readily apparent to those skilled in the art that the embedded contact pad 23 and the suspended heater element 28 can be formed together during deposition of the heater element material and subsequent etching during fabrication of the MEMS. . Thus, the embedded contact pad 23 can be made of the same material as the heater element, such as titanium nitride, titanium aluminum nitride, and the like.

Turning now to Figure 14, it should be noted that the ink ejection surface of the printhead IC2 is completely flat and coated with a layer of hydrophobic PDMS 48. The PDMS coating and its advantages are described in detail in U.S. Patent Publication No. 2008/0225082, the disclosure of which is incorporated herein by reference. As mentioned above, the flatness of the ink exit surface, including the portion of the surface within the longitudinal edge region 4 of the printhead integrated circuit 2, provides significant benefits in printhead maintenance and surface flooding. .

Although in FIG. 14 and 15, the contact pad is shown schematically adjacent to the nozzle 102, it should be understood that the contact pad 24 in the print head IC2 typically occupies the print head IC 100 (FIG. 1). In a similar position to the bond pad 105, a corresponding number of turns through connectors 14 extend into the file substrate 20. However, an advantage of the present invention is that the contact pads 24 need not be spaced apart from the inkjet nozzles 102 as the bond pads 105, and the bond pads need to have sufficient enveloping space to accommodate wire bonding and wire bond cladding. Thus, the backside TAB film connection can use helium more efficiently and reduce the overall width of each IC, or a greater number of nozzles 102 can be formed over the same IC width. For example, 60-70% of the IC width in the print head IC 100 is dedicated to the ink jet nozzle 102, but the present invention allows more than 80% of the IC width to be used for the ink jet nozzle. This feature is a significant advantage because helium is the most expensive component of a page wide ink printer.

MEMS process for a printhead IC with backside electrical connections

A MEMS process for the print head IC2 shown in Figure 14 will now be described in detail. The MEMS process includes a number of modifications to the process described in U.S. Patent Application Serial No. 12/323,471, which is incorporated herein incorporated by reference. Although the MEMS process is described in detail herein for exemplary purposes, it will be understood by those skilled in the art that any modification of any ink jet nozzle process will provide a print for backside electrical connections. Head integrated circuit. The applicant of the present application has implicitly referred to a MEMS process for fabricating the thermally actuated printhead IC shown in FIG. Accordingly, the invention is not intended to be limited to the particular nozzle assembly 101 described below.

16 to 25 show the sequence of MEMS fabrication steps used to form the print head IC 2 shown in Fig. 14. The completed print head IC2 includes a plurality of nozzle assemblies 101 and features that can be connected back to the CMOS circuit 113 on the back side.

The starting point for MEMS fabrication is a standard CMOS wafer comprising the germanium substrate 20 and a CMOS circuit 113 formed on the front side of the wafer. At the end of the MEMS process, the wafer is sliced into individual printhead integrated circuits (ICs) by slitting street etches that define each column fabricated from the wafer. The size of the print head IC.

Although the description herein is directed to a MEMS process implemented on the CMOS layer 113, it will be appreciated that the CMOS layer 113 can comprise multiple CMOS layers (eg, 3 or 4 CMOS layers) and is typically Passivated. The CMOS layer 113 may be passivated with a layer of tantalum oxide, or more commonly a standard 'ONO' stack, which comprises a layer of tantalum nitride sandwiched between two layers of tantalum oxide. Thus, the CMOS layer 113 referred to herein implicitly includes a passivated CMOS layer, which typically includes a multi-layer CMOS.

The following description focuses on the manufacturing steps of a nozzle assembly 101 and a through connector 14. However, it will be apparent that the corresponding steps can be performed simultaneously for all nozzle assemblies and all of the through connectors.

In the first of the steps shown in FIG. 16, a front side entrance aperture 32 is etched through the CMOS layer 113 and into the germanium substrate 20 of the CMOS wafer. At the same time, a front side slit street hole 33 is etched through the CMOS layer 113 and into the germanium substrate. A photoresist 31 is then applied to the front side of the wafer to plug the front side entrance aperture 32 and the slit street aperture 33. The wafer is then polished by chemical mechanical honing (CMP) to provide the wafer shown in Figure 16 having a flat front side surface ready for subsequent MEMS steps.

Referring to Figure 17, in the next step, an 8 micron thick low stress yttrium oxide layer is deposited onto the CMOS layer 113 by electrically enhanced chemical vapor deposition (PECVD). The depth of this yttria layer 35 defines the depth of each nozzle chamber of the spray nozzle assembly. After depositing the SiO ₂ layer 35, subsequent etching through the SiO ₂ layer defines a wall 36 for the nozzle chamber and a portion of the front side slitting street aperture 33. An etch chemistry is then used to extend the front side slit street opening 33 and etch the ink inlet opening 32 into the ruthenium substrate 20. The resulting holes 32 and 33 are then plugged by applying a photoresist 31 thereto and planarized using CMO honing. The photoresist 31 is a sacrificial material that functions as a construction frame for subsequent deposition of roof material. It will be apparent that other suitable sacrificial materials (e.g., polyimine) may also be used.

The wall material (e.g., yttria, tantalum nitride, or a combination thereof) is deposited on the planarized SiO ₂ layer 35 to define the front side top wall layer 37. The wall layers 37 will define a rigid planar nozzle plate in the finished printhead IC2. Figure 17 shows the wafer after the completion of the MEMS processing step of this sequence.

In the next stage, referring to FIG. 18, a plurality of conductor vias 38 are etched down through the top wall layer 37 and the SiO ₂ layer 35 to the CMOS layer 113. The conductor post holes 38A that are etched through the wall 36 can connect the nozzle actuator to the underlying CMOS layer 113. At the same time, the conductor via hole 38B can be electrically connected between the contact shop 4 and the underlying CMOS layer 113.

In a modification of the process described in U.S. Patent Application Serial No. 12/323,471, the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire The SiO ₂ layer 35, the CMOS layer 113, enters the crucible substrate 20 (see Figure 19) and is defined in the next step. The through-holes 39 are arranged to be spaced apart along a longitudinal edge region of each of the print heads IC2. (The front side slit street hole 33 effectively defines a longitudinal edge region of each of the print head IC2.) Each of the regular holes 39 is gradually narrowed toward the back side of the base substrate 20. The exact positioning of the through holes 39 is determined by the positioning of the film contacts 10 in the TAB film 8, which is in contact with the base of each hole when the print head IC is assembled and attached to the TAB film.

The through-hole via etching is performed by patterning a photoresist mask layer and etching through different layers. Of course, etching through different layers requires different etch chemistries, but the same photoresist mask can be used on each etch.

Each through-hole 39 typically has a depth to the depth of the crucible substrate 20 that corresponds to the depth of the plugged front side ink inlet 32 (typically about 20 microns). However, each of the constant holes 39 may be formed deeper than the front side ink inlet 32 in accordance with the thickness of the TAB film 8.

In the next step procedure, and with reference to Figures 20 and 21, the meandering through-hole 39 is provided with an insulating wall 21 that isolates the through-hole from the tantalum substrate 20. The insulating walls 21 include an insulating film 42 and a diffusion barrier 43. The diffusion barrier 43 minimizes diffusion of copper into the germanium substrate 20 as each of the wells 39 is filled with copper. The insulating film 42 and the diffusion barrier 43 are formed by a continuous deposition step, which is optionally used to the mask layer 40 for selectively depositing each layer into the via 39.

The insulating film 42 can be formed by any suitable insulating material such as an amorphous type, polycrystalline germanium, cerium oxide or the like. The diffusion barrier 43 is typically a ruthenium film.

Referring next to Fig. 22, the conductor vias 38 and the through vias 39 are simultaneously filled with a highly conductive metal such as copper to be electrolessly plated. The copper deposition step simultaneously forms the nozzle conductor post 44, the contact pad conductor post 30 and the turns through connector 14. The diameter of the through holes 38 and 39 will need to be sized to ensure simultaneous copper plating during this step. After the copper plating step, the deposited copper is subjected to CMP and is stopped at the top wall layer 37 to provide a flat structure. It can be seen that the conductor posts 30 and 44 formed during electroless copper plating are in contact with the CMOS layer 113 to provide a linear conductive path from the CMOS layer to the top wall layer 37.

In the next step procedure, referring to Figure 23, a thermoelastic material is deposited on the top wall layer 37 and then etched to define the thermoelastic beam member 25 for each nozzle assembly 101 and the contact pad 24 is covered. This turns through the head of the connector 14.

Welded to the heat due to the elastic beam member 25, so that the SiO 46 generally acts like a _two wall layer portion of the mechanical system under an inert beam thermal bend actuator member 37. Thus each nozzle assembly 101 includes a thermal bending actuator that includes a thermoelastic beam 25 coupled to the CMOS layer 113, and a lower passive beam 46. A variety of these types of thermal bending actuators are described in more detail in U.S. Patent Publication No. 2008/309, the disclosure of which is incorporated herein by reference.

The thermoelastic beam member 25 can be composed of any suitable thermoelastic material such as titanium nitride, titanium aluminum nitride and aluminum alloy. As described in the Applicant's U.S. Patent Publication No. 2008/129793, the disclosure of which is incorporated herein by reference in its entirety, the vanadium-aluminum alloy is a preferred material because Advantageous features of high thermal expansion, low density and high Young's modulus.

As mentioned above, the thermoelastic material is also used to define the contact pad 24. The contact pads 24 extend between the heads of the conductor posts 30 and the head 22 of the meandering connector 14. Thus, the contact pad 24 electrically connects the turns through connector 14 to each of the conductor posts 30 and the underlying CMOS layer 113.

Still referring to FIG. 23, after depositing the thermoelastic material and etching to define the thermal bending actuator and contact pad 24, the final front side MEMS fabrication step includes simultaneously etching the nozzle openings 102 and a front side street opening 47 and depositing a A PDMS coating 48 is applied over the entire top wall layer 37 to dewater the front side surface and provide a resilient mechanical seal for each thermal bending actuator. The use of the PDMS coating is described in detail in the Applicant's U.S. Patent Application Serial No. 11/685,084, the entire disclosure of which is incorporated herein by reference.

Referring now to Figure 24, the entire front side of the wafer is coated with a relatively thick photoresist 49 that protects the front side MEMS structure and allows the wafer to be attached to a handle crystal for backside MEMS processing. Round 50. The back side etch defines the ink supply conduit 110 and the recessed portion 6, the foot of the 矽through connector 14 extending into the recessed portion. A portion of the insulating film 42 is removed when the foot portion 15 of the 矽through connector 14 is etched away by the back side. The backside etch also singulates the printhead IC into individual printhead ICs by etching down to the plugged frontside slitting street apertures 33.

The final oxide removal ('ashing') of the protective photoresist 49 can result in a single individual printhead IC2 and a fluid connection between the backside and the nozzle assembly 101. The print head IC 2 produced as shown in Fig. 25 is now ready to be connected to the TAB film 8 through the solder ball 16 via the through connector 14. Subsequent bonding of the resulting printhead IC/TAB film assembly to the ink supply manifold can provide the printhead assembly 60 without the Figure 14.

The invention has been described with reference to a preferred embodiment and several specific modified embodiments. It will be appreciated by those skilled in the art, however, that other embodiments, which are different from the specific details described, will fall within the spirit and scope of the invention. Therefore, it is understood that the invention is not intended to be limited to the specific embodiments described herein (including the references herein). The scope of the invention is limited only by the scope of the following claims.

100. . . Print head IC

102. . . nozzle

104. . . Color pipeline

106. . . Connector

107. . . Triangle shape

110. . . Ink supply pipe

112. . . Nozzle inlet

114. . . Ink catheter

116. . . wall

120. . . Adhesive film

130. . . Print head assembly

122. . . PCL mold

124. . . PCL pipe mould

126. . . PCL main pipeline

127. . . Ink inlet

128. . . Ink outlet

129. . . Cavitation

132. . . Ink supply channel

134. . . Laser drilled supply hole

135. . . pipeline

103A. . . Benchmark

103B. . . Benchmark

125. . . Opening

140. . . Flexible PCB

142. . . Wire bonding sealant

144. . . Electronic component

148. . . Paper guide

160. . . Inkjet printer

146. . . contact

150. . . Wire bonding point

152. . . Connector column

154. . . Ink jet surface

2. . . Print head IC

60. . . Print head assembly

6. . . Dorsal under recess

4. . . Longitudinal edge region

8. . . TAB film

10. . . Membrane contact

12. . . Dorsal surface

15. . . Foot

20. . . Bismuth substrate

twenty one. . . Insulated sidewall

14. . .矽through connector

twenty two. . . head

twenty four. . . Contact pad

26. . . MEMS layer

113. . . CMOS circuit layer

101. . . Inkjet nozzle assembly

25. . . Thermoelastic actuator

30. . . Conductor column

twenty three. . . Embedded contact pad

27. . . Passivation layer

31. . . Photoresist

37. . . Top wall

28. . . Suspended heater element

32. . . Front entrance hole

33. . . Front side slitting street hole

35. . . Cerium oxide layer

36. . . wall

38A. . . Conductor column through hole

38B. . . Conductor column through hole

39. . .矽through through hole

40. . . Photoresist

42. . . Insulating film

43. . . Diffusion barrier

44. . . Nozzle conductor post

46. . . Lower passivation beam

47. . . Front side street opening

48. . . PDMS coating

49. . . Photoresist

50. . . Processing wafer

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which:

Figure 1 is a front perspective view of a row of head integrated circuit;

Figure 2 is a front perspective view of a pair of adjacent printhead integrated circuits;

Figure 3 is a rear perspective view of the print head integrated circuit shown in Figure 1;

Figure 4 is a cutaway perspective view of an inkjet jet assembly having a bottom nozzle inlet;

Figure 5 is a cutaway perspective view of an inkjet jet assembly having a sidewall nozzle inlet;

Figure 6 is a side perspective view of a row of print head assemblies;

Figure 7 is a bottom perspective view of the print head assembly shown in Figure 6;

Figure 8 is a top exploded perspective view of the print head assembly shown in Figure 6;

Figure 9 is a bottom exploded perspective view of the print head assembly shown in Figure 6;

Figure 10 is a stacked plan view of a row of print head integrated circuits attached to an ink supply manifold;

Figure 11 is an enlarged view of Figure 10;

Figure 12 is a perspective view of an ink jet printer;

Figure 13 is a schematic cross-sectional view of the print head assembly shown in Figure 6;

Figure 14 is a schematic cross-sectional view of a printhead assembly in accordance with the present invention;

Figure 15 is a schematic cross-sectional view of another print head assembly in accordance with the present invention;

16 to 24 are schematic cross-sectional views of a wafer after different stages of manufacturing a stack of integrated circuit circuits in accordance with the present invention; and

Figure 25 is a schematic cross-sectional view showing a row of head integrated circuits in accordance with the present invention.

60. . . Print head assembly

26. . . MEMS layer

113. . . CMOS circuit layer

2. . . Print head IC

20. . . Bismuth substrate

6. . . Dorsal under recess

8. . . TAB film

120. . . Adhesive film

124. . . PCL pipe mould

10. . . Membrane contact

twenty one. . . Insulated sidewall

15. . . Foot

16. . . Solder ball

4. . . Longitudinal edge region

14. . .矽through connector

twenty two. . . head

twenty four. . . Contact pad

30. . . Conductor column

102. . . nozzle

25. . . Thermoelastic actuator

101. . . Inkjet nozzle assembly

44. . . Nozzle conductor post

154. . . Ink jet surface

114. . . Ink catheter

112. . . Nozzle inlet

110. . . Ink supply pipe

12. . . Dorsal surface

Claims (14)

A print head integrated circuit comprising: a substrate having a front side, a back side for attaching to an ink manifold, and at least one ink supply channel providing flow communication to the front side and Between the sides; at least one CMOS layer on the front side, comprising a driving circuit; and a MEMS layer disposed on the COMS layer such that the CMOS layer is disposed between the germanium substrate and the MEMS layer, The MEMS layer includes a plurality of inkjet nozzle assemblies, wherein: a plurality of through-connectors extend through a thickness of the tantalum substrate, each through-connector linearly extending from a contact pad in the MEMS layer, through the a CMOS layer facing the back side; one end of each individual through connector defines an integrated circuit contact; and the integrated circuit contacts are electrically connected to the CMOS layer through one or more conductor posts, One or more conductor posts extend linearly between each contact pad and the CMOS layer. The print head integrated circuit of claim 1, wherein the back side has a concave portion for receiving a connection end of a connector film. The print head integrated circuit of claim 2, wherein the recessed portion is defined along a longitudinally long edge region of each of the print head integrated circuits. For example, the print head integrated circuit of claim 2, wherein The recessed portion includes the integrated circuit contacts. The print head integrated circuit of claim 2, wherein when the back side is attached to an ink supply manifold, the connection end is sandwiched between at least a portion of the ink supply manifold and the print Between the header integrated circuits. The print head integrated circuit of claim 1, wherein each of the through connectors is tapered toward the back side. For example, the print head integrated circuit of claim 1 wherein each of the through connectors is made of copper. The print head integrated circuit of claim 1, wherein each of the through connectors has an outer side wall including an insulating film. The print head integrated circuit of claim 8, wherein the outer sidewalls comprise a diffusion barrier layer between the insulating film and a conductive core of the through connector. The print head integrated circuit of claim 1, wherein a front side surface of the print head is flat and does not have any wire bonding connections. The print head integrated circuit of claim 10, wherein the front side surface is coated with a hydrophobic polymer layer. The print head integrated circuit of claim 10, wherein the hydrophobic polymer layer is composed of PDMS. The print head integrated circuit of claim 2, wherein the back side has a plurality of ink supply channels extending longitudinally along the print head integrated circuit, each ink supply channel defining one or more Ink inlets for receiving ink from the ink supply manifold, wherein each ink supply The channels supply ink to a plurality of front side inlets, and each front side inlet supplies ink to one or more ink jet nozzle assemblies. A print head integrated circuit as in claim 13 wherein each of the ink supply passages has a depth corresponding to a depth of the depressed portion.