MXPA06005397A - Microfluid ejection device having efficient logic and driver circuitry - Google Patents

Abstract

A semiconductor substrate for a microfluid ejection head. The substrate includes a plurality of fluid ejection actuators disposed on the substrate. A plurality of driver transistors are disposed on the substrate for driving the plurality of fluid ejection actuators. Each of the driver transistors have an active area ranging from about 1000 to less than about 15,000µm2. A plurality of logic circuits including at least one logic transistor are coupled to the driver transistors. The driver and logic transistors are provided by a high density array of MOS transistors wherein at least the logic transistors have a gate length of from about 0.1 to less than about 3 microns.

Description

APPARATUS FOR THE EXPULSION OF MICROFLUIDS THAT HAVE AN EFFICIENT LOGIC AND IMPULSOR CIRCUIT SYSTEM Field of the Invention The present invention relates to apparatus for the ejection of microfluidics and in particular to ejection heads for ejection apparatuses containing an efficient logic and a driving circuit system.

Background of the Invention Microfluid ejection devices, such as jet inkjet printers, continue to experience widespread acceptance as inexpensive replacements for laser printers. These ink jet printers are generally more versatile than laser printers for some applications. As the capabilities of ink jet printers are increased, to provide higher quality images at increased print rates, the ejector heads that are the main printing components of jet inkjet printers continue to evolve and become more complex As the complexity of the ejector heads increases, so does the cost to produce the ejector heads. However, there continues to be a need for microfluidic ejection apparatuses having improved capabilities including improved quality and higher production rates. The competitive pressure on print quality and prices, promotes the continuous need to produce ejection heads with improved capabilities in a more economical way.

Summary of the Invention With respect to the above and other objects and advantages, a semiconductor substrate for a microfluidic ejection head is provided. The substrate includes a plurality of fluid ejecting actuators positioned on the substrate. A plurality of driving transistors are placed on the substrate to drive the plurality of fluid ejection actuators. Each of the driving transistors has an active area in a range of about 1000 or less than about 15,000 μm2. A plurality of logic circuits that include at least one logic transistor are connected to the drive transistors. The impeller and the logic transistors are provided by a high density array of MOS transistors, wherein at least the logic transistors have a switching pulse length of from about 0.1 to less than about 3 microns. In another embodiment, a microfluidic ejection cartridge for a microfluidic ejection apparatus is provided. The cartridge body has a fluid supply source and an ejection head adhered to the cartridge body in fluid communication with the fluid supply source. The ejection head includes a semiconductor substrate having a plurality of fluid ejecting actuators positioned on the substrate. A plurality of driving transistors placed on the substrate to drive the plurality of fluid ejection actuators. Each of the driving transistors has an active area in a range of about 100 or less than about 400 microns. A plurality of logic circuits which include at least one logic transistor are operatively connected to the drive transistors. The driving and logic transistors comprise a high density array of MOS transistors wherein at least the logic transistor has a switching pulse length of from about 0.1 to less than about 3 microns. A nozzle plate is adhered to the semiconductor substrate to expel fluids therefrom at the time of activation of the fluid ejection actuators. In yet another embodiment, a semiconductor substrate for a jet ink jet head is provided. The substrate includes a plurality of heater resistors placed on the substrate. The heater resistors have a protective layer diamond-like carbon with a thickness in a range of about 1000 to about 3000 Angstroms. A plurality of driving transistors are placed on the substrate to drive the plurality of fluid ejection actuators. A plurality of logic circuits include at least one logic transistor that is connected to the drive transistors. The driver and logic transistors provide a high density array of MOS transistors wherein at least the logic transistors have a switching pulse length of from about 0.1 to less than about 3 microns. An advantage of the present invention is that it provides microfluidic ejection heads for microfluidic ejection devices that require substantially less substrate area and still provide increased functionality. Semiconductor substrates can be used for a wide variety of applications, including ink jet print heads, microfluidic cooling devices, the supply of controlled amounts of pharmaceutical preparations, and the like. In the applications of the ink jet printer, the substrates of the present invention can significantly reduce the manufacturing costs and raw materials of the print heads by incorporating the ejection heads.

BRIEF DESCRIPTION OF THE FIGURES Additional advantages of the present invention may be appreciated by reference to the detailed description of the preferred embodiments when considered in conjunction with the following drawings which illustrate one or more non-limiting aspects of the invention, wherein the characters similar references designate like or similar elements in the different figures in the manner > Fig. 1 'is a cartridge of a microfluidic ejection apparatus, not to scale, containing a microfluidic ejection head according to the present invention; Figure 2 is a perspective view of a preferred microfluidic ejection apparatus according to the present invention; Figure 3 is a cross-sectional view that is not to scale of a portion of a microfluidic ejection head according to the present invention; Figure 4 is a schematic drawing of a logic circuit according to the present invention; Figure 5 is a schematic drawing of an inverter for a logic circuit according to the present invention; Figure 6 is a cross-sectional view, not to scale, of a portion of the transistors of the logic circuit according to the present invention; Figures 7 and 8 are cross-sectional views, which are not to scale of portions of the driving transistors according to the present invention; Figure 9 is a plan view, not in scale, of a portion of an impeller transistor according to the present invention; Figure 10 is a plan view that is not to scale of a typical distribution in a substrate for a microfluidic ejection head according to the present invention; Figure 11 is a plan view, which is not to scale of a portion of an active area of a microfluidic ejection head according to the present invention; and Figure 12 is a partial schematic view of a logic diagram for a microfluidic ejection apparatus according to the present invention.

Detailed Description of the Invention With reference to Figure 1, a fluid cartridge 10 for a microfluidic ejection apparatus is illustrated. The cartridge 10 includes a cartridge body 12, for supplying a fluid to a fluid ejection head 14. The fluid may be contained in a storage area in the cartridge body 12, or it may be supplied from a source remote to the body of the cartridge. The fluid ejection head 14 includes a semiconductor substrate 16 and a nozzle plate 18 containing the nozzle holes 20. It is preferred that the cartridge be adhered so that it can be removed to a microfluidic ejection apparatus, such as a ink jet printer 22 (figure 2). Accordingly, electrical contacts 24 are provided in a flexible circuit 26 for electrical connection to the microfluidic ejection apparatus. The flexible circuit 26 includes the electrical cables 28 which are connected to the substrate 16 in the fluid ejection head 14. An enlarged view, not to scale, of a portion of the fluid ejection head 14 is illustrated in Figure 3. In this case, the fluid ejection head 14 contains a thermal heating element 30 as a fluid ejecting actuator for heating the fluid in a fluid chamber 32 formed in the nozzle plate 18 between the substrate 16 and the hole of the nozzle 20. However, the present invention is not limited to a fluid ejection head 14 which contains a thermal heating element 30. In the case of the thermal heating elements 30, the heating elements are heater resistors. which preferably have a protective layer comprising carbon-like diamond with a thickness range of from about 1000 to about 3000 Angstroms. Other fluid ejection actuators, such as piezoelectric apparatuses can also be used to produce a fluid ejection head according to the present invention. The fluid is provided to the fluid chamber 32 through an opening or slot 34 in the substrate 16 and through a fluid channel 36 that connects the slot 34 to the fluid chamber 32. The nozzle plate 18 is preferably adhesive adhered to the substrate 16 by a layer of adhesive 36. As illustrated in Figure 3, the flow characteristics including the fluid chamber 32 and the fluid channel 36 are formed in the nozzle plate 18. However , the flow characteristics can be provided in a separate thick film layer and wherein a nozzle plate containing only nozzle holes is adhered to the thick film layer. In a particularly preferred embodiment, the fluid ejection head 14 is a thermal or piezoelectric jet ink printhead. However, the invention is not intended to be limited to ink jet print heads, since other fluids may be ejected with the fluid ejecting apparatus according to the present invention. Referring again to Figure 2, the fluid ejection apparatus is preferably a jet inkjet printer 22. The printer 22 includes a cart 40 to hold one or more cartridges 10 and to move the cartridges 10 over the media 42 such as the paper depositing a fluid from the cartridges 10 in the means 42. As explained above, the contacts 24 of the cartridge coincide with the contacts of the cart 40 to provide the electrical connection between the printer 22 and the cartridge . The microcontrollers of the printer 22 control the movement of the cart 40 across the width of the means 42 and to convert analog and / or digital inputs of an external device, such as a computer, to control the operation of the printer. . The expulsion of fluid from the fluid ejection head 14 is controlled by a logic circuit 44 in the fluid ejection head 14, in conjunction with the printer controller 22. Figures 4 and 5 illustrate a logic circuit Preferred 44 for a fluid ejection head 14. The logic circuit 44 includes a NAND regulator 46, with the inlets 48 of the microfluidic ejection apparatus or printer 22 and has an outlet to an inverter 50. A preferred inverter 50 is a circuit Logical CMOS illustrated in Figure 5, and includes an NMOS transistor 52 on a P-type substrate and an adjacent PMOS transistor 54 provided by an NWELL on a P-type substrate. The output of the inverter 50 is tied to a switching pulse 56 of a driving transistor 58 that drives the fluid actuator, and in this case a thermal heating element 30. There is at least one driving transistor 58 adjacent to each heater element 30. The heater element 30 is preferably a resistor having a resistance in a range of about 70 to about 150 ohms or more, and more preferably of about 100 to about 120 ohms. In Figure 6 a cross-sectional view, not to scale, of an inverter 50 is illustrated as described above. As stated above, inverter 50 includes an NMOS transistor 52 and a PMOS transistor 54. Each of transistors 52 and 54 preferably has regulators 60 and 62 that have switching pulse lengths in a range of approximately 0.1. to less than about 3 microns, more preferably from about 0.1 to about 1.5 microns. In a similar manner, the channels of the substrate 64 or NWELL 66 preferably have a channel length in a range from about 0.1 to less than about 3 microns. By providing a smaller regulator and channel length, a higher density of the transistors 52 and 54 can be provided for an area of a substrate containing the logic circuit 44. Other characteristics of the transistors 52 and 54 are conventional and the inverter 50 is produced by conventional semiconductor processing techniques. The transverse views, not to scale, of the preferred transistors 68 and 70 are illustrated in Figures 7 and 8. Figure 9 is a simplified plan view of an impeller transistor 68. Figure 7 is an impeller transistor 68 having a slightly impurified draining region 72, while the driving transistor 70 both contains a lightly doped source region 74 and a slightly doped drainage region 76. It is also preferred that the driving transistors 68 and 70 include the regulators 78 and 80 having lengths of switching pulse LG in a range from about 0.1 to less than about 3 microns and preferably from about 0.1 to about 1.5 microns and channels having Lc channel lengths (Figure 9) in a range from about 0.1 to less than about 3 microns . The length of the regulator LG of the driving transistors 68 and 70 makes it possible for the driving transistors to have a lower resistance. Generally, the resistance of the driving transistors 68 and 70 is less than 10% of the total resistance provided in the circuit by the heater resistors 30, the logic circuit 44, the driving transistor 68 or 70 and the associated connector circuit system. Said drive transistors 68 and 70 are preferably operated at a voltage greater than 8 volts, preferably from about 8 to approximately 12 volts. The driving transistor 68 or 70 includes a substrate 82 which is preferably a type P silicone substrate. The areas 84 and 86 are an N-doped source and drain regions for the transistors 68 and 70. The area 88 is a region P-impurified which provides a zero potential for the source contacts of transistor 90 and 92. Other characteristics of the transistors 68 and 70 are conventional and transistors 68 and 70 are made by conventional semiconductor processing techniques. It is preferred that the driving transistor 68 or 70 have a resistance of less than 20 ohms, preferably from about 1 to less than about 20 ohms. Figure 10 shows a plan view, not to scale, of a fluid ejector head 14. The fluid ejector head 14 includes a semiconductor substrate 16 and a nozzle plate 18 adhered to the substrate 16. A distribution of the areas of the apparatus of the semiconductor substrate 16 which provides the preferred locations for the logic circuit system 44, the drive transistors 58 and the heater resistors 30. As shown in Fig. 10, the substrate 16 includes a single slot 34 to provide fluids, such as ink, to the heater resistors 30 which are positioned on both sides of the slot 34. However, the present invention is not limited to a substrate 16 having a single slot 34 or to the fluid ejecting actuators, such as the heater resistors 30 placed on both sides of the slot 34. Other substrates according to the present invention may include multiple slots with action. fluid ejecting devices placed on one or both sides of the slots. The substrate may also not include slots 34, where the fluid flows around the edges of the substrate 16 to the actuators. Instead of a single slot 34, the substrate 16 may include multiple slots or openings, in each of the one or more actuator apparatuses. The nozzle plate 18 preferably being made of an ink-resistant material such as polyimide is adhered to the substrate 16.

An active area 94 required for the drive transistors 58 is illustrated in detail in a plan view of the active area 94 in FIG. 11. This figure represents a portion of a typical heater array and an active area. The active area 94 of the substrate 16 preferably has dimensions of width W in a range of about 100 to about 400 microns and an overall dimension of length D in a range of about 6,300 microns to about 26,000 microns. The drive transistors 58 are provided in a pitch range P of about 10 microns to about 84 microns. A ground bus 96 and a power bus 98 are provided to supply power to the appliances in the active area 94 and to the heater resistors 30. In a particularly preferred embodiment, the area of a single driving transistor 58 in the semiconductor substrate 16 has an active area width in a range of about 100 to less than about 400 microns and an active area preferably less than about 15,000 μm2. The smallest active area 94 is made possible by the use of the drive transistors 58 having switching pulse lengths and channel lengths in a range from about 0.1 to less than about 3 as described above. In a similar way, a smaller area is required for the logic circuit 44 (FIG. 10) due to the use of transistors 52 and 54 having switching pulse lengths in a range of about 0.1 to less than about 3 microns. Fig. 12 is a simplified partial logic diagram for a microfluidic ejection apparatus, such as the printer 22 (Fig. 2) according to the present invention. The apparatus includes a main control system 100 connected to the fluid ejection head 14. As described above with reference to Figure 10, the fluid ejection head 14 includes a logic circuit system 44, impellers of the apparatus 58 and fluid ejecting actuators 30 connected to the impellers of the apparatus 58. A programmable memory apparatus 102 may be located in the ejector head 14 or in the control system 100 of the printer 22. The printer 22 includes a supply of energy 104 and an AC to DC converter 106. The AC to DC converter 106 provides the energy for the ejecting head 14 and for an analog-to-digital converter 108. The analog-to-digital converter 108 accepts a signal 110 from a external source such as a computer and provides the signal to a controller 112 of the printer 22. The controller 112 contains the logic devices, to control the function of the The ejector 14. The controller 112 also contains a local memory and logic circuits for programming and reading the memory 102, if any, in the ejecting head 14. It is contemplated and may be appreciated by those skilled in the art from the foregoing description and the accompanying drawings, which modifications and changes may be made in the embodiments of the present invention. Accordingly, it is expressly intended that the foregoing description and the accompanying drawings be illustrative only of the preferred embodiments, not limited thereto and that the actual spirit and scope of the present invention be determined by reference to the appended claims.

Claims (30)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as property:
2. CLAIMS 1. A semiconductor substrate for a fluid ejection head, the substrate comprising: a plurality of fluid ejecting actuators positioned on the substrate; a plurality of driving transistors placed on the substrate to drive the plurality of fluid ejection actuators, each of the driving transistors having an active area in a range from about 1000 to less than about 15,000 μm2; and a plurality of logic circuits comprising at least one logic transistor that is connected to the drive transistors, wherein each of the logic transistors and drivers comprise a high density array of MOS transistors wherein at least the logic transistors have a switching pulse length from about 0.1 to less than about 3 microns. The semiconductor substrate according to claim 1, characterized in that the fluid ejection actuators comprise heater resistors.
3. 3. The semiconductor substrate according to claim 2, characterized in that the heater resistors have a resistance range of about 70 to about 150 ohms.
4. The semiconductor substrate according to claim 1, characterized in that the driving transistors comprise transistors having a slightly contaminated drainage region.
5. The semiconductor substrate according to claim 1, characterized in that the driving transistors have an active area width in a range of about 100 to less than about 400 microns.
6. 6. The semiconductor substrate according to claim 1, characterized in that the logic circuits are configured to select a regulator of the driving transistors to drive the ejection actuators.
7. The semiconductor substrate according to claim 1, characterized in that the drive transistors have a resistance of less than about 20 ohms.
8. The semiconductor substrate according to claim 1, characterized in that the driving transistors comprise transistors having slightly contaminated drainage and source regions.
9. 9. The semiconductor substrate according to claim 1, characterized in that the driving transistors comprise transistors having a switching pulse length in a range from about 0.1 to less than about 3 microns.
10. The semiconductor substrate according to claim 1, characterized in that the driving transistors comprise transistors having a channel length in a range from about 0.1 to less than about 3 microns.
11. 11. A print head for a jet ink printer containing the semiconductor substrate according to claim 1.
12. 12. A print head according to claim 11, characterized in that the fluid ejection actuators comprise heater resistors. and the heater resistors have a protective layer comprising carbon-like diamond with a thickness range of from about 1000 to about 3000 Angstroms.
13. 13. A microfluidic ejection cartridge for a microfluidic ejection apparatus which comprises: a cartridge body having a fluid supply source and an ejection head adhered to the cartridge body in fluid communication with the source of supply of fluid. fluids, the ejection head comprising: a semiconductor substrate having a plurality of fluid ejecting actuators positioned on the substrate; a plurality of driving transistors placed on the substrate to drive the plurality of fluid ejection actuators, each of the driving transistors having an active area width in a range of about 100 to less than about 400 microns; and a plurality of logic circuits comprising at least one logic transistor operatively connected to the driving transistors, wherein each of the driving and logic transistors comprises a high density array of MOS transistors wherein at least the logic transistor has a switching pulse length of from about 0.1 to less than about 3 microns; and a nozzle plate adhered to the semiconductor substrate to eject the fluid therefrom upon activation of the fluid ejecting actuators.
14. The microfluidic ejection cartridge according to claim 13, characterized in that the fluid ejecting actuators comprise heater resistors having a resistance range between about 70 to about 150 ohms.
15. 15. The microfluidic ejection cartridge according to claim 13, characterized in that the active area of the substrate of each of the driving transistors is in a range of about 1000 to less than about 15,000 μm2.
16. The microfluidic ejection cartridge according to claim 13, characterized in that the driving transistors comprise transistors having a slightly contaminated drainage region.
17. The microfluidic ejection cartridge according to claim 13, characterized in that the logic circuits are configured to select a switching pulse of the driving transistors to drive the ejection actuators.
18. 18. The microfluidic ejection cartridge according to claim 13, characterized in that the driving transistors have a resistance of less than about 20 ohms.
19. The microfluidic ejection cartridge according to claim 13, characterized in that the driving transistors comprise transistors having slightly contaminated drainage and source regions.
20. The microfluidic ejection cartridge according to claim 12, characterized in that the fluid ejection actuators comprise heater resistors and the heater resistors have a protective layer comprising carbon-like diamond with a thickness range of about 1000 up to approximately 3000 Angstroms.
21. 21. The microfluidic ejection cartridge according to claim 12, characterized in that the driving transistors comprise transistors having a switching pulse length in a range from about 0.1 to less than about 3 microns.
22. 22. A semiconductor substrate for a jet ink jet printhead, the substrate comprising: a plurality of heater resistors placed on the substrate, the heater resistors having a protective layer comprising carbon-like diamond with a thickness range of about 1000 to about 3000 Angstr .; a plurality of driving transistors placed on the substrate to drive the plurality of fluid ejection actuators; and a plurality of logic circuits comprising at least one logic transistor that is connected to the drive transistors; wherein each of the driving and logic transistors comprises a high density array of MOS transistors wherein at least the logic transistors have a switching pulse length of from about 0.1 to less than about 3 microns.
23. 23. The semiconductor substrate according to claim 22, characterized in that the heater resistors have a resistance range of about 70 to about 150 ohms.
24. 24. The semiconductor substrate according to claim 22, characterized in that the driving transistors comprise transistors having a slightly contaminated drainage region.
25. 25. The semiconductor substrate according to claim 22, characterized in that the driving transistors have an active area width in a range of about 100 to less than about 400 microns.
26. 26. The semiconductor substrate according to claim 22, characterized in that the logic circuits are configured to select a regulator of the driving transistors to drive the ejection actuators.
27. 27. The semiconductor substrate according to claim 22, characterized in that the driving transistors have a resistance of less than about 20 ohms.
28. 28. The semiconductor substrate according to claim 22, characterized in that the driving transistors comprise transistors having slightly contaminated drainage and source regions.
29. 29. The semiconductor substrate according to claim 22, characterized in that the driving transistors comprise transistors having a switching pulse length in a range from about 0.1 to less than about 3 microns.
30. 30. The semiconductor substrate according to claim 22, characterized in that the driving transistors comprise transistors having a channel length in a range from about 0.1 to less than about 3 microns.