Liquid discharging head and method of manufacturing liquid discharging head

Abstract

To suppress roughness of the bottom surface of a channel at the time when forming a channel by dry-etching the substrate from both surfaces of the substrate.SOLUTION: A method of manufacturing a liquid discharging head including channels for liquid includes the steps of: forming a first channel for liquid having a recessed shape by dry-etching a substrate from a first surface thereof; forming a protection film by using a material different from the substrate on a bottom surface of the first channel; forming a plurality of second channels for liquid each having a recessed shape by dry-etching the substrate from a second surface opposite the first surface of the substrate, so as to be connected to the bottom surface of the first channel; and opening the plurality of second channels through to the bottom surface of the first channel by removing the protection film in the connection of the second channel on the bottom of the first channel by dry etching from a second surface side. Therein an etching rate of a material of the protection film is lower than an etching rate of a material of the substrate during the dry-etching for forming the plurality of second channels in the substrate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid ejection head and a method for manufacturing the liquid ejection head.

Background Art

[0002] There is an inkjet recording apparatus that performs recording by ejecting liquid from a liquid ejection head having a plurality of nozzles onto a recording medium. The liquid ejection head includes an element substrate having a plurality of pressure generation chambers provided corresponding to each of the plurality of nozzles and a piezoelectric element provided in the plurality of pressure generation chambers, and the liquid in the pressure generation chamber is ejected from the nozzle by driving the piezoelectric element. The element substrate is provided with a plurality of flow paths communicating with the plurality of pressure generation chambers and a common flow path communicating with the plurality of flow paths, and the liquid is supplied to the pressure generation chamber by supplying liquid from the outside to the common flow path. The common flow path and the plurality of flow paths communicating therewith are formed by forming recesses by dry etching from both surfaces of the substrate. Patent Document 1 describes that a flow path of a plurality of small openings is formed by dry etching from the first surface of the substrate, and a flow path of a large opening communicating with the flow paths of the plurality of small openings is formed by dry etching from the second surface on the opposite side.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] After forming a first flow path as a recess with a large opening by dry etching from the first surface of the substrate, a second flow path is formed as a recess with a small opening by dry etching from the second surface of the substrate, and a through hole is formed in the substrate so that a plurality of second flow paths open to the bottom surface of the first flow path. In this case, when the second flow path penetrates the bottom surface of the first flow path, the bottom surface of the first flow path may be roughened by the etching gas that has flowed into the bottom surface of the first flow path from the penetrated opening. If roughening occurs, there is a possibility that fragments of the substrate will break off and become foreign matter in a later process. Also, when liquid is discharged, air bubbles may accumulate in the roughness of the first flow path, and the discharge function may deteriorate. Further, when a protective film is formed on the flow path wall surface including the bottom of the first flow path, the protective film may peel off due to the roughness.

[0005] An object of the present invention is to suppress roughening of the bottom surface of a flow path when forming the flow path by dry etching from both surfaces of a substrate.

Means for Solving the Problems

[0006] The present invention is a method for manufacturing a liquid discharge head having a substrate having a liquid flow path, forming a concave first flow path from the first surface of the substrate by dry etching; forming a protective film on the bottom surface of the first flow path with a material different from that of the substrate; forming a plurality of concave second flow paths from the second surface of the substrate opposite to the first surface of the substrate by dry etching so as to connect to the bottom surface of the first flow path; removing the protective film at a portion where the second flow path connects to the bottom surface of the first flow path from the second surface side by dry etching to open the plurality of second flow paths to the bottom surface of the first flow path; and In the dry etching in the step of forming the second flow path in the substrate, the etching rate of the material of the protective film is lower than the etching rate of the material of the substrate. A method for manufacturing a liquid discharge head, characterized in that.

[0007] The present invention relates to a liquid ejection head having a substrate made of silicon with a liquid flow path, a concave-shaped first flow path provided on a first surface of the substrate, a plurality of concave-shaped second flow paths provided on a second surface of the substrate opposite to the first surface, the plurality of second flow paths opening to a bottom surface of the first flow path, a protective film made of a material different from that of the substrate provided at a portion of the bottom surface of the first flow path where the plurality of second flow paths do not open, and having, with respect to etching of the silicon constituting the substrate, an etching rate of the material of the protective film being lower than an etching rate of the silicon constituting the substrate, the liquid ejection head being characterized in this regard.

Effects of the Invention

[0008] According to the present invention, it becomes possible to suppress roughening of the bottom surface of the flow path when forming the flow path by dry etching from both surfaces of the substrate.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described with reference to the drawings. In the embodiments described below, specific descriptions may be made in order to fully explain the present invention, but these show a technically preferable example and do not particularly limit the scope of the present invention.

[0011] The embodiment described below is an inkjet recording apparatus in which a liquid such as ink is circulated between a tank and a liquid ejection device, but other forms may also be used. For example, instead of circulating the ink, two tanks may be provided on the upstream side and the downstream side of the liquid ejection device, and the ink may be flowed from one tank to the other tank to flow the ink in the pressure chamber.

[0012] Further, the embodiment described below is a recording apparatus having a so-called line type head having a length corresponding to the width of a recording medium, but the present invention can also be applied to a so-called serial type liquid ejection device that performs recording while scanning the recording medium. Examples of the serial type liquid ejection device include, but are not limited to, a configuration in which one element substrate for black ink and one element substrate for color ink are mounted. It may also be a form in which a short line head shorter than the width of the recording medium, in which several element substrates are arranged so that the nozzles overlap in the nozzle row direction, is scanned with respect to the recording medium.

[0013] The schematic configuration of an apparatus that ejects the liquid of the embodiment, particularly an inkjet recording apparatus (hereinafter referred to as a recording apparatus) 1000 that ejects ink to perform recording, is shown in FIG. 7. The recording apparatus 1000 is a recording A line-type recording apparatus includes a conveyance unit 1 that conveys a recording medium 2, and a line-type liquid ejection head 18 disposed substantially orthogonally to the conveyance direction of the recording medium 2, and performs continuous recording in one pass while continuously or intermittently conveying a plurality of recording media 2. The liquid ejection head 18 is connected to a liquid supply means that is a supply path for supplying liquid to the liquid ejection head 18. Further, a control unit 900 that transmits power and an ejection control signal to the liquid ejection head 18 is electrically connected to the liquid ejection head 18.

[0014] The configuration of the liquid ejection head 18 according to the embodiment will be described. FIGS. 8(a) and 8(b) are perspective views of the liquid ejection head 18. The liquid ejection head 18 is a line-type liquid ejection head in which a plurality of (15 in the embodiment) element substrates 80 are linearly arranged (arranged in-line). As shown in FIG. 8(a), the liquid ejection head 18 includes a plurality of element substrates 80, and the element substrates 80 are electrically connected to a signal input terminal 91 and a power supply terminal 92 via a flexible wiring substrate 76 and an electrical wiring substrate 90. The signal input terminal 91 and the power supply terminal 92 are electrically connected to the control unit 900 of the recording apparatus 1000. An ejection drive signal is supplied to the element substrate 80 via the signal input terminal 91, and power required for ejection is supplied to the element substrate 80 via the power supply terminal 92. As shown in FIG. 8(b), the liquid connection portions 111 provided at both ends of the liquid ejection head 18 are connected to the liquid supply system of the recording apparatus 1000. Thereby, ink is supplied from the supply system of the recording apparatus 1000 to the liquid ejection head 18, and the ink that has passed through the liquid ejection head 18 is recovered to the supply system of the recording apparatus 1000. Thus, the ink of each color can circulate through the path of the recording apparatus 1000 and the path of the liquid ejection head 18.

[0015] Fig. 9(a) shows a perspective view of one ejection module 200, and Fig. 9(b) shows an exploded view thereof. As a manufacturing method of the ejection module 200, first, the element substrate 80 and the flexible wiring substrate 76 are adhered to a support member 74 provided with a liquid communication port 75 in advance. Then, the terminal 86 of the element substrate 80 and the terminal 77 of the flexible wiring substrate 76 are electrically connected by wire bonding, and then the wire bonding portion (electrical connection portion) is covered and sealed with a sealing material 110. The terminal 78 on the side of the flexible wiring substrate 76 opposite to the element substrate 80 is electrically connected to the connection terminal 93 (see Fig. 8(a)) of the electrical wiring substrate 90. The support member 74 is a support body that supports the element substrate 80 and is a flow path member that fluidly communicates the element substrate 80 and the liquid connection portion 111. The support member 74 preferably has high flatness and can be joined to the element substrate 80 with sufficient reliability. As the material, for example, alumina or a resin material is preferable.

[0016] The configuration of the element substrate 80 in the embodiment will be described. Fig. 10(a) shows a plan view of the surface of the element substrate 80 on which the nozzles 20 are formed, and Fig. 10(b) shows an enlarged view of the portion indicated by A in Fig. 10(a). As shown in Fig. 10(a), four nozzle rows corresponding to each ink color are formed in the flow path forming member 82 of the element substrate 80. The direction in which the nozzle rows in which a plurality of nozzles 20 are arranged extends is referred to as the "nozzle row direction". The nozzle row direction is parallel to the plane portion of the element substrate 80. The nozzle row direction is the Y direction (second direction), the direction intersecting the nozzle row direction and parallel to the plane portion of the element substrate 80 and intersecting the nozzle row direction is the X direction (first direction), and the direction perpendicular to the plane portion of the element substrate 80 is the Z direction (third direction). In the embodiment, the Y direction, the X direction, and the Z direction are perpendicular to each other.

[0017] As shown in FIG. 10(b), a piezoelectric element 14 for varying the pressure of the liquid is disposed at a position corresponding to each nozzle 20. A pressure generating chamber 19 (cavity) having the piezoelectric element 14 therein is partitioned by a partition wall 72. The piezoelectric element 14 is electrically connected to the terminal 86 in FIG. 10(a) by electrical wiring (not shown) provided on an element substrate 80. The piezoelectric element 14 deforms based on a pulse signal input from the control circuit of the recording apparatus 1000 via an electrical wiring substrate 90 and a flexible wiring substrate 76 (see FIG. 8), thereby varying the pressure of the liquid. Due to this pressure variation, the liquid is discharged from the nozzle 20. As shown in FIG. 10(b), along each nozzle row, a liquid supply path 88 extends on one side and a liquid recovery path 89 extends on the other side. The liquid supply path 88 and the liquid recovery path 89 are flow paths extending in the nozzle row direction (Y direction) provided on the element substrate 80, and communicate with the pressure generating chamber 19 via a supply port 87a and a recovery port 87b, respectively. The supply port 87a and the recovery port 87b are provided side by side in the X direction. The pressure variation causes the liquid to be discharged from the nozzle 20. As shown in FIG. 10(b), along each nozzle row, a liquid supply path 88 extends on one side and a liquid recovery path 89 extends on the other side. The liquid supply path 88 and the liquid recovery path 89 are flow paths extending in the nozzle row direction (Y direction) provided on the element substrate 80, and communicate with the pressure generating chamber 19 via a supply port 87a and a recovery port 87b, respectively. The supply port 87a and the recovery port 87b are provided side by side in the X direction.

[0018] Next, the flow of the liquid in the element substrate 80 will be described. FIG. 11 is a perspective view showing a cross section of the element substrate 80 and the cover plate 70 taken along line B-B in FIG. 10(a). The element substrate 80 is formed by laminating a substrate 81 made of Si and a flow path forming member 82 made of a photosensitive resin, and a cover plate 70 is joined to the back surface of the substrate 81. A piezoelectric element 14 is formed on one surface side of the substrate 81, and grooves constituting a liquid supply path 88 and a liquid recovery path 89 extending along the nozzle row direction (Y direction) are formed on the back surface side thereof.

[0019] The liquid supply path 88 and the liquid recovery path 89 formed by the substrate 81 and the cover plate 70 are respectively connected to a common supply flow path and a common recovery flow path in a flow path member (not shown), and a differential pressure is generated between the liquid supply path 88 and the liquid recovery path 89. When recording is performed by discharging liquid from the plurality of nozzles 20 of the liquid discharge head 18, in the nozzles 20 where the discharge operation is not being performed, due to this differential pressure, the liquid in the liquid supply path 88 provided in the substrate 81 flows into the liquid recovery path 89. The flow is a flow via the supply port 87a, the pressure generation chamber 19, and the recovery port 87b, and is indicated by the arrow C in FIG. 11.

[0020] Due to this flow, in the nozzles 20 and the pressure generation chamber 19 where recording is paused, thickened ink generated by evaporation from the nozzles 20, bubbles, foreign substances, etc. can be recovered into the liquid recovery path 89. Also, thickening of the ink in the nozzles 20 and the pressure generation chamber 19 can be suppressed. The liquid recovered into the liquid recovery path 89 passes through the opening 71 of the cover plate 70 and the liquid communication port 75 of the support member 74 (see FIG. 9(b)), and is recovered in the order of a communication port, an individual recovery flow path, and a common recovery flow path in a flow path member (not shown). And finally, it is recovered into the supply path of the recording apparatus 1000.

[0021] A plurality of supply ports 87a communicate with the liquid supply path 88, and the liquid supply path 88 is a common flow path that supplies liquid to the plurality of supply ports 87a. A plurality of recovery ports 87b communicate with the liquid recovery path 89, and the liquid recovery path 89 is a common flow path that recovers liquid from the plurality of recovery ports 87b. In the substrate 81, a common flow path (liquid supply path 88, liquid recovery path 89) with a large opening is formed by etching from the lower surface side, and a plurality of individual flow paths (supply port 87a, recovery port 87b) with small openings are formed by etching from the upper surface side. By etching until a plurality of individual flow paths open on the bottom surface of the common flow path, the bottom surface of the common flow path penetrates, and a through hole that penetrates the substrate 81 with the common flow path and the plurality of individual flow paths is formed.

[0022] The liquid ejection head 18 is a member of the recording apparatus 1000. The recording apparatus 1000 is also provided with a liquid storage unit that stores the liquid to be supplied to the liquid ejection head 18, a transport mechanism for the recording medium 2 on which recording is performed, and the like.

[0023] Example 1 1 is a cross-sectional view of an element substrate 80 constituting a liquid ejection head 18 of Example 1. The element substrate 80 is configured by bonding a protection substrate 13 having a first flow path 11 and a second flow path 12, an actuator substrate 16 having a piezoelectric element 14 and a vibration membrane 15, and a nozzle substrate 17.

[0024] The actuator substrate 16 is made of, for example, silicon, and has a plurality of pressure generating chambers 19. The vibration membrane 15 on the actuator substrate 16 forms the ceiling wall of the pressure generating chambers 19. It defines a pressure generating chamber 19. A piezoelectric element 14 is disposed on the vibration membrane 15.

[0025] A nozzle substrate 17 is bonded to the actuator substrate 16. A nozzle 20 is formed on the upper surface of the nozzle substrate 17. The nozzle 20 penetrates the nozzle substrate 17 from the surface opposite to the pressure generating chamber 19 toward the pressure generating chamber 19. When a change in the volume of the pressure generating chamber 19 occurs, the liquid stored in the pressure generating chamber 19 is ejected from the nozzle 20.

[0026] The protective substrate 13 is made of, for example, silicon. The protective substrate 13 is disposed so as to cover the piezoelectric elements 14, and is bonded to the surface of the actuator substrate 16 via an adhesive 21. The protective substrate 13 has recesses 22 on the surface facing the surface of the actuator substrate 16. A plurality of corresponding piezoelectric elements 14 are housed in the recesses 22.

[0027] On the protective substrate 13, a first flow path 11 formed to open to the surface 26 of the protective substrate 13 and a second flow path 12 formed to open to the back surface 28 of the protective substrate 13 are formed. The side opposite to the back surface 28 of the second flow path 12 is formed to open to the bottom surface 25 of the first flow path 11. The second flow path 12 communicates with a pressure generation chamber 19 formed in the actuator substrate 16. A flow path penetrating the protective substrate 13 is formed by the first flow path 11 and the second flow path 12. The area of the bottom surface of the first flow path 11 is larger than the area of the opening of the second flow path 12. A protective film 23 with a slow etching rate for Si etching is formed on the bottom surface 25 of the first flow path 11. The etching rate of the material of the protective film 23 is lower than the etching rate of silicon, which is the material of the protective substrate 13. Due to the protective film 23, a flat surface with a flatness Ra = 1.0 μm or less is formed on the bottom surface 25 of the first flow path 11.

[0028] The element substrate 80 is formed by joining a protective substrate 13 as a first substrate, an actuator substrate 16 and a nozzle substrate 17 as second substrates. The protective substrate 13 as the first substrate has a concave-shaped first flow path 11 provided on a surface 26 which is a first surface. Further, the protective substrate 13 has a plurality of concave-shaped second flow paths 12 provided on a back surface 28 which is a second surface opposite to the first surface. The plurality of second flow paths 12 open to a bottom surface 25 of the first flow path 11. The protective film 23 is made of a material different from that of the protective substrate 13 which is the first substrate, and is provided at a portion of the bottom surface 25 of the first flow path 11 where the plurality of second flow paths 12 do not open. The actuator substrate 16 and the nozzle substrate 17 constituting the second substrate are joined such that the actuator substrate 16 is joined to the back surface 28 which is the second surface of the protective substrate 13 as the first substrate. The nozzle substrate 17 constituting the second substrate has a plurality of nozzles 20 for discharging liquid and a plurality of pressure generation chambers 19 which are a plurality of liquid chambers for supplying liquid to each of the plurality of nozzles 20. The plurality of pressure generation chambers 19 communicate with respective ones of the plurality of second flow paths 12 of the protective substrate 13 which is the first substrate. A plurality of energy generation means corresponding to each of the plurality of pressure generation chambers 19, which generate energy for discharging liquid from each of the plurality of nozzles 20, are provided. In Example 1, the energy generation means includes a diaphragm 15 constituting a part of a wall surface of the pressure generation chamber 19 and a piezoelectric element 14 provided on the diaphragm 15. In Example 1, in the thickness direction of the protective substrate 13 which is the first substrate, the length (depth) D1 of the first flow path 11 is shorter (shallower) than the length (depth) D2 of the second flow path 12.

[0029] Since the protective film 23 is not formed on the side wall 27 of the second flow path 12, a decrease in the cross-sectional area of the second flow path 12 can be suppressed, and an increase in the flow path resistance can be suppressed. Further, since the protective film 23 is formed on the bottom surface 25 of the first flow path 11, roughness of the bottom surface 25 of the first flow path 11 can be suppressed.

[0030] Regarding the protective film 23 having a slow etching rate with respect to Si etching, it may be formed of a resin film such as a resist. Even in this case, there is an effect of suppressing roughness of the bottom surface 25 of the first flow path 11. However, in the case of a resist resin film, it is necessary to remove it by subsequent flow.

[0031] FIG. 6 is a diagram showing a comparative example for comparison with Example 1. As shown in FIG. 6, consider the case where there is no protective film 23 with a slow etching rate on the bottom surface 25 of the first flow path 11. After forming the first flow path 11 by etching from the surface 26 side of the protective substrate 13, the second flow path 12 is formed by etching from the back surface 28 side of the protective substrate 13, penetrating the bottom surface 25 of the first flow path 11. At this time, the etching gas of Si may flow into the bottom surface 25 of the first flow path 11, and a phenomenon may occur in which the bottom surface 25 of the first flow path 11 becomes rough. Due to this roughness 61, foreign matter may be generated during the subsequent process, and the yield and the discharge function may be reduced.

[0032] In addition, this roughness 61 is more likely to occur significantly when the ratio of the depth D1 of the first flow path 11 to the depth D2 of the second flow path 12 is D1 / D2 < 1. That is, the deeper the depth D2 of the second flow path 12, the longer the over-etching time required to absorb the etching rate difference across the entire wafer. Therefore, the part with a faster rate penetrates first, and the etching gas flows into the first flow path 11 side, so the roughness 61 of the bottom surface 25 of the first flow path 11 is likely to occur. When the roughness 61 occurs, the Si chip may be detached and become foreign matter in the subsequent process. Also, when discharging the liquid, a bubble pool may be generated at the roughness 61, and the discharge function may be reduced.

[0033] On the other hand, in Example 1, since the bottom surface 25 of the first flow path 11 becomes a flat surface and the occurrence of roughness is suppressed, the generation of foreign matter and the generation of a bubble pool during discharge can be suppressed.

[0034] A method for manufacturing the element substrate 80 of the liquid discharge head 18 of Example 1 will be described with reference to FIG. 2.

[0035] In Example 1, the device substrate 80 is manufactured using dry etching. Dry etching is generally a method of introducing a reactive gas into a processing chamber to form a plasma, and using the plasmaized reactive gas to etch the processing surface of the substrate to form a predetermined shape. Specifically, the substrate is fixed to the lower electrode in the processing chamber, for example, by an electrostatic chuck, and the reactive gas is supplied from the micro holes of the upper electrode to which a high-frequency power source is connected between the lower electrode and the upper electrode. The supplied reactive gas is plasmaized between the upper electrode and the lower electrode to etch the substrate and form a predetermined shape. As a dry etching method, for example, reactive ion etching using an etching gas can be used. Reactive ion etching is suitable for making the through hole have a vertical shape. When forming a liquid supply port, which is a through hole, in the substrate of a liquid ejection head typified by an inkjet head, it is preferable to use reactive ion etching.

[0036] First, as shown in Fig. 2(a), a 600-μm-thick silicon substrate serving as the protective substrate 13 was prepared.

[0037] Next, as shown in Fig. 2(b), a concave-shaped first flow path 11 was formed from the surface 26 side of the protective substrate 13. An etching mask (not shown) was made of a novolak-based photoresist, and an opening pattern was formed by exposure and development. Thereafter, using this mask, Si dry etching was performed to form a recess serving as the first flow path 11 up to the middle in the thickness direction of the protective substrate 13. The etching depth was 200 μm, and an etching method called the so-called Bosch process, which uses SF6 gas in the etching step and C4F8 gas in the coating step, was used. However, it is also possible to form it by a method other than the Bosch process.

[0038] Next, the etching mask was removed, and as shown in Fig. 2(c), a protective film 23 was formed on the bottom surface 25 of the first flow path 11 with a material having a low etching rate with respect to Si, which is the material of the protective substrate 13, from the surface 26 side of the protective substrate 13. In Example 1, a silicon oxide film was formed as the protective film 23 by plasma CVD (P-CVD). As the etching rate, when Si, which is the material of the protective substrate 13, is taken as 1, a protective film is formed with a material having an etching rate of 0.01 or less, preferably 0.005 or less. The oxide film is a film that is hardly etched. The film thickness was 20 0 nm. As a result, even when over-etching was performed in consideration of the rate distribution when etching the subsequent second flow path 12, it was possible to perform etching without penetration. Note that the formation of the protective film 23 is not limited to the plasma CVD method. There is no problem as long as a film with a thickness equal to or greater than the film thickness that can withstand etching and having an etching rate equal to or less than that of the atomic layer deposition method (ALD method) can be formed.

[0039] Next, as shown in Fig. 2(d), a plurality of concave-shaped second flow paths 12 were formed from the back surface 28 side of the protective substrate 13 by Si dry etching using the etching mask 24 as a mask so as to be connected to the bottom surface 25 of the first flow path 11. As the Si etching conditions at that time, a method called the so-called Bosch process using an etching step and a coating step was used.

[0040] Next, as shown in Fig. 2(e), in order to remove the protective film 23 at the portion where the second flow path 12 is connected on the bottom surface 25 of the first flow path 11, oxide film etching was performed to open the plurality of second flow paths 12 to the bottom surface 25 of the first flow path 11. Thereby, the first flow path 11 and the second flow path 12 were communicated. As the subsequent oxide film etching conditions, a mixed gas of C4F8 gas, CF4 gas, and Ar gas was used. As an example of the oxide film etching conditions, for example, the gas pressure was controlled at 0.3 Pa, the gas flow rate was 500 sccm, the coil power was 1500 W, and the platen power was 400 W. Under these conditions, the oxide film was etched, but Si was hardly etched.

[0041] Thereafter, the etching mask 24 was removed, and as shown in FIG. 2(f), the recess 22 was formed from the back surface 28 side of the protective substrate 13. The piezoelectric element 14 is covered by the recess 22. Another etching mask (not shown) was previously patterned on the lower surface of the previous etching mask 24, and after removing the etching mask 24, the recess 22 was formed by Si etching. Note that a resist mask may be formed by a dry film, and the recess 22 may be formed by performing Si dry etching.

[0042] Next, a plurality of nozzles 20, and a plurality of pressure generating chambers 19 which are a plurality of individual channels that supply liquid to each of the plurality of nozzles 20 and communicate with each of the second channels 12 of the protective substrate 13 are formed, and the actuator substrate 16 and the nozzle substrate 17 are prepared. Then, as shown in FIG. 2(g), the actuator substrate 16 and the nozzle substrate 17 were bonded to the back surface 28 which is the second surface of the protective substrate 13 via the adhesive 21. The adhesive application method was carried out by spin-coating the adhesive on the dry film and transferring it to the protective substrate 13. However, the adhesive application method is not limited to this, and it may also be carried out by screen printing or photolithographic patterning using a photosensitive adhesive.

[0043] Through the above steps, the element substrate 80 for the liquid ejection head 18 of Example 1 was manufactured.

[0044] (Example 2) Example 2 will be described with reference to the cross-sectional view of FIG. 3. The element substrate 80 of Example 2 has a heating element 31 as a means for generating energy used to eject liquid. The heating element 31 is an electrothermal conversion element that generates thermal energy to cause film boiling in the liquid when energized. After forming the first channel 11 and the second channel 12 on the substrate 40 having the heating element 31, an orifice plate 32 is formed, and the nozzle 20 for ejecting liquid is formed. A protective film 23 with a slow etching rate for Si etching is formed on the bottom surface 25 of the first channel 11. That is, the protective film 23 is a film with a high etching selectivity. As the protective film 23, a silicon oxide film was formed by P-CVD.

[0045] Regarding the ratio of the depth D1 of the first flow path 11 to the depth D2 of the second flow path 12, in order to improve the refilling performance and reduce the flow path resistance near the heating element 31, it is preferable to shorten (shallow) the second flow path 12. In the second embodiment, in the thickness direction of the substrate 40 which is the first substrate, the length (depth) D1 of the first flow path 11 is longer (deeper) than the length (depth) D2 of the second flow path 12. When the ratio of the depths is D1 / D2 > 1, the roughness 61 described in FIG. 6 is less likely to occur. Also, since the protective film 23 is not formed on the side wall of the second flow path 12, a decrease in the cross-sectional area of the second flow path 12 can be suppressed, and an increase in the flow path resistance can be suppressed. Further, since the protective film 23 is formed on the bottom surface 25 of the first flow path 11, it becomes possible to suppress the roughness of the bottom surface 25 of the first flow path 11. Thereby, the generation of foreign matters and the generation of air bubbles can be suppressed, and an element substrate 80 having more stable discharge performance can be obtained.

[0046] With reference to FIG. 4, a method for manufacturing the element substrate 80 for the liquid discharge head 18 of the second embodiment will be described.

[0047] First, as shown in FIG. 4(a), a substrate 40 having a heating element 31 and wiring (not shown) for driving the same formed on the surface 29 of a silicon single crystal substrate with an ingot pulling orientation of <100> was prepared. The substrate thickness was 600 μm.

[0048] Next, as shown in FIG. 4(b), an etching mask (not shown) was patterned on the back surface 30 opposite to the surface 29 on which the heating element 31 was formed, and the first flow path 11 was formed by dry etching. As the etching mask, a novolak-based positive resist was used and patterned by photolithography. The depth of the first flow path 11 was 500 μm.

[0049] Next, as shown in FIG. 4(c), a protective film 23 having a low etching rate with respect to Si etching was formed on the bottom surface 25 of the first flow path 11. Here, an oxide film was formed by P-CVD as the protective film 23.

[0050] Next, as shown in FIG. 4(d), an etching mask 41 for forming the second flow path 12 was patterned from the surface 29 side where the heating element 31 was formed, and the second flow path 12 was formed by Si dry etching. Then, the protective film 23 at the location where the second flow path 12 should open on the bottom surface 25 of the first flow path 11 was etched to connect the first flow path 11 and the second flow path 12.

[0051] Thereafter, as shown in FIG. 4(e), an orifice plate 32 in which a liquid flow path 42 and a nozzle 20 were formed was formed on the surface 29 side of the substrate 40 to form the element substrate 80. As a method of forming the orifice plate 32 on the substrate 40 where the first flow path 11 and the second flow path 12 communicate, a method using a support and a photosensitive resin can be considered. After forming the photosensitive resin on the support, the photosensitive resin is installed so as to straddle the opening of the substrate 40. The support is, for example, a film, glass, or silicon wafer. Since the support needs to be peeled off later, a film is preferred. For example, the support is a polyethylene terephthalate (PET) film, a polyimide film, or a polyamide film. Also, a film subjected to a release treatment may be used to facilitate peeling.

[0052] As the photosensitive resin, a first photosensitive resin for forming the liquid flow path 42 and a second photosensitive resin for forming the orifice plate 32 are used. After patterning the first photosensitive resin on the support, the second photosensitive resin is formed on the first photosensitive resin, through holes serving as nozzles 20 are provided in the second photosensitive resin, and then the first photosensitive resin is removed, whereby the orifice plate 32 can be formed. As the first photosensitive resin, an epoxy resin that dissolves in an organic solvent can be used. Thereby, it becomes possible to remove the first photosensitive resin using an organic solvent. Also, the first photosensitive resin may be an acrylic resin or a urethane resin. Note that, as a method of patterning the first photosensitive resin, a spin coating method, a slit coating method, a transfer method such as a lamination method or a press method, or the like can be used.

[0053] (Example 3) FIG. 5 shows a cross-sectional view of the element substrate 80 of Example 3. The description will focus on the differences from Example 1 and Example 2. As shown in FIG. 5, a Si protective film 51 was formed on the element substrate 80 fabricated in Example 1. The Si protective film 51 was formed by atomic layer deposition (ALD method), and at least one material selected from the group consisting of tantalum oxide, titanium oxide, hafnium oxide, and zirconium oxide was continuously formed.

[0054] In Example 3, the Si protective film 51 was a tantalum oxide film with a film thickness of 0.1 μm (100 nm). When the bottom surface 25 of the first flow path 11 where the first flow path 11 and the second flow path 12 communicate was rough, the Si protective film formed on the bottom surface 25 of the first flow path 11 might peel off. In Example 3, since the protective film 23 was formed on the bottom surface 25 of the first flow path 11 where the Si protective film 51 was formed, there was no roughness, and peeling of the Si protective film 51 was suppressed. Thereby, the reliability of the element substrate 80 and the liquid ejection head 18 can be enhanced.

[0055] The disclosure of the present embodiment includes the following configurations. (Method 1) A method for manufacturing a liquid ejection head having a substrate with a liquid flow path, forming a concave first flow path from a first surface of the substrate by dry etching; forming a protective film on the bottom surface of the first flow path with a material different from the substrate; forming a plurality of concave second flow paths from a second surface of the substrate opposite to the first surface of the substrate so as to connect to the bottom surface of the first flow path by dry etching; removing the protective film at a portion where the second flow path connects on the bottom surface of the first flow path from the side of the second surface by dry etching to open the plurality of second flow paths on the bottom surface of the first flow path; and having In the dry etching in the step of forming the second flow path in the substrate, a method for manufacturing a liquid ejection head, characterized in that an etching rate of the material of the protective film is lower than an etching rate of the material of the substrate. (Method 2) A step of forming, on a second substrate, a plurality of nozzles for ejecting a liquid, a plurality of liquid chambers for supplying a liquid to each of the plurality of nozzles, the plurality of liquid chambers communicating with each of the plurality of second flow paths of the substrate, and a plurality of energy generation means corresponding to each of the plurality of liquid chambers, the plurality of energy generation means generating energy for ejecting a liquid from each of the plurality of nozzles; A step of bonding the second substrate to the second surface of the substrate; The method for manufacturing a liquid ejection head according to Method 1 having the above. (Method 3) The method for manufacturing a liquid ejection head according to Method 2, wherein the energy generation means includes a diaphragm constituting a part of a wall surface of the liquid chamber and a piezoelectric element provided on the diaphragm. (Method 4) The method for manufacturing a liquid ejection head according to Method 3, wherein a length of the first flow path in a thickness direction of the substrate is shorter than a length of the second flow path. (Method 5) The method for manufacturing a liquid ejection head according to Method 2, wherein the energy generation means includes an electrothermal conversion element that generates thermal energy to cause film boiling in a liquid by energization. (Method 6) The length of the first flow path in the thickness direction of the substrate is longer than the length of the second flow path in Method 5 The method for manufacturing a liquid ejection head described above. (Method 7) The method for manufacturing a liquid ejection head according to any one of Methods 1 to 6, wherein when the etching rate of the material of the substrate is set to 1, the etching rate of the material of the protective film is 0.01 or less. (Method 8) The method for manufacturing a liquid ejection head according to any one of Methods 1 to 7, wherein the material of the substrate is silicon and the protective film is a silicon oxide film. (Method 9) The manufacturing method of the liquid ejection head according to any one of Methods 1 to 7, wherein the material of the substrate is silicon and the protective film is a resin film. (Method 10) In the step of forming the protective film, the manufacturing method of the liquid ejection head according to any one of Methods 1 to 9, wherein the protective film is formed by plasma CVD method or atomic layer deposition method. (Configuration 11) A liquid ejection head having a substrate made of silicon having a liquid flow path, A concave-shaped first flow path provided on a first surface of the substrate, A plurality of concave-shaped second flow paths provided on a second surface of the substrate opposite to the first surface, the plurality of second flow paths opening to a bottom surface of the first flow path, A protective film made of a material different from that of the substrate provided on a portion of the bottom surface of the first flow path where the plurality of second flow paths do not open, And having, Regarding the etching of the silicon constituting the substrate, the etching rate of the material of the protective film is lower than the etching rate of the silicon constituting the substrate. A liquid ejection head characterized by this. (Configuration 12) A second substrate joined to the second surface of the substrate, A plurality of nozzles for ejecting liquid, A plurality of liquid chambers for supplying liquid to each of the plurality of nozzles, the plurality of liquid chambers communicating with each of the plurality of second flow paths of the substrate, A plurality of energy generating means corresponding to each of the plurality of liquid chambers, the plurality of energy generating means generating energy for ejecting liquid from each of the plurality of nozzles, The liquid ejection head according to Configuration 11, having a second substrate having the above. (Configuration 13) The energy generating means includes a vibration film constituting a part of the wall surface of the liquid chamber and a piezoelectric element provided on the vibration film. The liquid ejection head according to Configuration 12. (Configuration 14) The liquid ejection head according to Configuration 13, wherein the length of the first flow path in the thickness direction of the substrate is shorter than the length of the second flow path. (Configuration 15) The liquid ejection head according to Configuration 12, wherein the energy generating means includes an electrothermal conversion element that generates thermal energy to cause film boiling in the liquid by energization. (Configuration 16) The liquid ejection head according to Configuration 15, wherein the length of the first flow path in the thickness direction of the substrate is longer than the length of the second flow path. (Configuration 17) The liquid ejection head according to any one of Configurations 11 to 16, wherein the protective film is not provided on the side wall of the second flow path. (Configuration 18) The liquid ejection head according to any one of Configurations 11 to 17, wherein the protective film is a silicon oxide film. (Configuration 19) The liquid ejection head according to any one of Configurations 11 to 17, wherein the protective film is a resin film. (Configuration 20) The liquid ejection head according to any one of Configurations 11 to 19, wherein the flatness of the bottom surface of the first flow path provided with the protective film is 1.0 μm or less.

Explanation of Reference Numerals

[0056] 11: First flow path, 12: Second flow path, 13: Protective substrate, 16: Actuator substrate, 17: Nozzle substrate, 18: Liquid ejection head, 19: Pressure generation chamber, 20: Nozzle, 23: Protective film, 25: Bottom surface of the first flow path, 26: Surface of the protective substrate, 28: Back surface of the protective substrate, 80: Element substrate

Claims

1. A method for manufacturing a liquid ejection head having a substrate with a liquid flow path, comprising: forming a concave first flow path from a first surface of the substrate by dry etching; forming a protective film on a bottom surface of the first flow path from a material different from that of the substrate; forming a plurality of concave second flow paths from a second surface of the substrate opposite to the first surface by dry etching so as to connect to the bottom surface of the first flow path; removing the protective film from the side of the second surface at a portion where the second flow path connects to the bottom surface of the first flow path by dry etching to open the plurality of second flow paths to the bottom surface of the first flow path; and in the dry etching in the step of forming the second flow path in the substrate, the etching rate of the material of the protective film is lower than the etching rate of the material of the substrate. A method for manufacturing a liquid ejection head characterized by this.

2. forming, on a second substrate, a plurality of nozzles for ejecting liquid, a plurality of liquid chambers for supplying liquid to each of the plurality of nozzles and communicating with each of the plurality of second flow paths of the substrate, and a plurality of energy generating means corresponding to each of the plurality of liquid chambers for generating energy for ejecting liquid from each of the plurality of nozzles; bonding the second substrate to the second surface of the substrate; The method for manufacturing a liquid ejection head according to claim 1, comprising this.

3. The method for manufacturing a liquid ejection head according to claim 2, wherein the energy generating means includes a vibration film constituting a part of a wall surface of the liquid chamber and a piezoelectric element provided on the vibration film.

4. The method for manufacturing a liquid ejection head according to claim 3, wherein in the thickness direction of the substrate, the length of the first flow path is shorter than the length of the second flow path.

5. The method for manufacturing a liquid ejection head according to claim 2, wherein the energy generating means includes an electrothermal conversion element that generates thermal energy to cause film boiling in the liquid by energization.

6. The method for manufacturing a liquid ejection head according to claim 5, wherein in the thickness direction of the substrate, the length of the first flow path is longer than the length of the second flow path.

7. When the etching rate of the material of the substrate is set to 1, the etching rate of the material of the protective film is 0.01 or less. The method for manufacturing a liquid ejection head according to any one of claims 1 to 6.

8. The method for manufacturing a liquid ejection head according to any one of claims 1 to 6, wherein the material of the substrate is silicon and the protective film is a silicon oxide film.

9. The method for manufacturing a liquid ejection head according to any one of claims 1 to 6, wherein the material of the substrate is silicon and the protective film is a resin film.

10. In the step of forming the protective film, the protective film is formed by a plasma CVD method or an atomic layer deposition method. The method for manufacturing a liquid ejection head according to any one of claims 1 to 6.

11. A liquid ejection head having a substrate made of silicon having a liquid flow path, a concave first flow path provided on a first surface of the substrate, a plurality of concave second flow paths provided on a second surface of the substrate opposite to the first surface, the plurality of second flow paths opening to a bottom surface of the first flow path, a protective film made of a material different from that of the substrate provided on a portion of the bottom surface of the first flow path where the plurality of second flow paths do not open, having, Regarding the etching of the silicon constituting the substrate, the etching rate of the material of the protective film is lower than the etching rate of the silicon constituting the substrate. A liquid ejection head characterized by this.

12. A second substrate joined to the second surface of the substrate, a plurality of nozzles for ejecting liquid, a plurality of liquid chambers for supplying liquid to each of the plurality of nozzles, the plurality of liquid chambers communicating with each of the plurality of second flow paths of the substrate, a plurality of energy generating means corresponding to each of the plurality of liquid chambers, the plurality of energy generating means generating energy for ejecting liquid from each of the plurality of nozzles, A liquid ejection head according to claim 11, having a second substrate having the above.

13. The liquid ejection head according to claim 12, wherein the energy generating means includes a vibration film constituting a part of a wall surface of the liquid chamber and a piezoelectric element provided on the vibration film.

14. The liquid ejection head according to claim 13, wherein the length of the first flow path in the thickness direction of the substrate is shorter than the length of the second flow path.

15. The liquid ejection head according to claim 12, wherein the energy generating means includes an electrothermal conversion element that generates thermal energy to cause film boiling in the liquid when energized.

16. The liquid ejection head according to claim 15, wherein the length of the first flow path in the thickness direction of the substrate is longer than the length of the second flow path.

17. The liquid ejection head according to any one of claims 11 to 16, wherein the protective film is not provided on the side wall of the second flow path.

18. The liquid ejection head according to any one of claims 11 to 16, wherein the protective film is a silicon oxide film.

19. The liquid ejection head according to any one of claims 11 to 16, wherein the protective film is a resin film.

20. The liquid ejection head according to any one of claims 11 to 16, wherein the flatness of the bottom surface of the first flow path provided with the protective film is 1.0 μm or less.

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