Recording element substrate and recording device

Abstract

To provide a recording element substrate that is used in a liquid discharge head that heats liquid using a heating resistor and discharges the liquid, which is improved in reliability.SOLUTION: A recording element substrate comprises: a heating resistor positioned on an insulation layer positioned on a substrate; an insulating protective film covering the heating resistor; a conductive protective film covering the insulating protective film; first electrical wiring and second electrical wiring buried in insulating layers; a first connecting member and a second connecting member, which are buried in the insulating layers to contact a lower surface of the heating resistor, which respectively electrically connect the heating resistor to the first electrical wiring and electrically connect the heating resistor to the second electrical wiring. Volumes of the first connecting member which is high potential of the first connecting member and the second connecting member are smaller than volumes of the second connecting member that is low potential.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a recording element substrate and a recording apparatus.

Background Art

[0002] There is a recording apparatus having a liquid ejection head of a type in which the liquid inside a liquid chamber is heated by energizing a heating resistor, and the liquid in the liquid chamber is foamed by film boiling of the liquid generated thereby, and droplets are ejected from a discharge port by the foaming energy at this time. In order to protect the heating resistor from physical and chemical actions during foaming, it is desirable to coat the heating resistor with an insulating protective film and a conductive protective film. However, the thinner the thickness of these protective layers, the more efficiently the heat generated by the heating resistor can be transferred to the liquid.

[0003] Patent Document 1 describes a recording element substrate having a configuration in which an insulating layer is formed on a substrate, an electrical wiring layer is formed in the insulating layer, and a heating resistor disposed on the insulating layer is connected to the electrical wiring layer by a connection member (electrode plug) embedded in the insulating layer. According to this configuration, since electrical connection is made to the heating resistor from the back side, electrical wiring is not required on the front side of the heating resistor. Therefore, the thickness of the protective layer can be made thinner compared to the case where electrical wiring is formed on the front side of the heating resistor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, holes are formed in a flat insulating layer, and an electrode plug is formed by filling the holes with a material for the electrode plug. When forming an electrode plug in a hole, depending on the shape of the electrode plug, voids (gaps) may occur in the electrode plug. Then, the embedding of the metal for forming the electrode plug becomes insufficient, and unevenness may occur on the surface of the formed electrode plug. In this case, there is a possibility that the insulating protective film formed on the heating resistor arranged above the electrode plug cannot uniformly cover the heating resistor, and in that case, there is a possibility that the conductive protective film and the heating resistor may be short-circuited. Patent Document 1 describes columnar and slit-shaped electrode plugs as the shapes of the electrode plugs. The slit-shaped electrode plug is relatively less likely to have surface unevenness, but has a larger volume than the columnar electrode plug.

[0006] Here, when dielectric breakdown occurs in the insulating protective film covering the heating resistor due to abnormal heating of the heating resistor or the like, the portion from the electrode plug to the insulating protective film and the conductive protective film may be blown into the pressure chamber by the impact, and the heating resistor may be disconnected. At this time, when the volume of the electrode plug is large like the slit-shaped electrode plug, even if it receives the impact of disconnection, a part of the electrode plug remains, and thereby there is a possibility that the heating resistor and the conductive protective film may be short-circuited.

[0007] An object of the present invention is to enhance the reliability of a recording element substrate used in a liquid discharge head that heats and discharges a liquid by a heating resistor.

Means for Solving the Problems

[0008] The present invention includes a substrate, an insulating layer located on the substrate, a heating resistor located on the insulating layer, which generates thermal energy for discharging a liquid when energized, an insulating protective film made of an insulator covering the heating resistor, a conductive protective film made of a conductor covering the insulating protective film, a first electrical wiring embedded in the insulating layer, A second electrical wiring embedded in the insulating layer, A first connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the first connection member electrically connecting the heating resistor and the first electrical wiring, A second connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the second connection member electrically connecting the heating resistor and the second electrical wiring, A recording element substrate having, A recording element substrate characterized in that the volume of the first connection member on the high potential side among the first connection member and the second connection member is smaller than the volume of the second connection member on the low potential side.

Advantages of the Invention

[0009] According to the present invention, the reliability of an element substrate used for a liquid ejection head that heats and ejects a liquid with a heating resistor can be improved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the following description does not limit the scope of the present invention.

[0012] The example is an inkjet recording apparatus in a form that circulates a liquid such as ink 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.

[0013] Further, the example is a recording apparatus having a so-called line type head having a length corresponding to the width of the 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 recording element substrate for black ink and one recording element substrate for color ink are mounted. A short line head shorter than the width of the recording medium, in which several recording element substrates are arranged so that the ejection ports overlap in the ejection port row direction, may be scanned with respect to the recording medium.

[0014] (Description of the recording apparatus) The schematic configuration of an apparatus that ejects the liquid of the example, particularly an inkjet recording apparatus 1000 (hereinafter referred to as a recording apparatus) that ejects ink to perform recording, is shown in FIG. 1. The recording apparatus 1000 includes a conveyance unit 1 that conveys a recording medium 2, and a line type liquid ejection head 3 that is arranged substantially orthogonal to the conveyance direction of the recording medium 2, and is a line type recording apparatus that performs continuous recording in one pass while continuously or intermittently conveying a plurality of recording media 2. The liquid ejection head 3 is connected to a liquid supply means that is a supply path for supplying the liquid to the liquid ejection head 3. Further, a control unit 900 that transmits electric power and a discharge control signal to the liquid ejection head 3 is electrically connected to the liquid ejection head 3.

[0015] (Description of the liquid ejection head) The configuration of the liquid ejection head 3 according to the embodiment will be described. FIGS. 2(a) and 2(b) are perspective views of the liquid ejection head 3. The liquid ejection head 3 is a line type liquid ejection head in which a plurality (15 in the embodiment) of recording element substrates 10 are arranged linearly (arranged in-line). As shown in FIG. 2(a), the liquid ejection head 3 includes a plurality of recording element substrates 10, and the recording element substrates 10 are electrically connected to a signal input terminal 91 and a power supply terminal 92 via a flexible wiring substrate 40 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. A discharge drive signal is supplied to the recording element substrate 10 via the signal input terminal 91, and power required for discharge is supplied to the recording element substrate 10 via the power supply terminal 92. As shown in FIG. 2(b), the liquid connection portions 111 provided at both ends of the liquid ejection head 3 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 3, and the ink that has passed through the liquid ejection head 3 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 3.

[0016] (Description of the ejection module) Fig. 3(a) shows a perspective view of one ejection module 200, and Fig. 3(b) shows an exploded view thereof. As a manufacturing method of the ejection module 200, first, the recording element substrate 10 and the flexible wiring substrate 40 are adhered onto a support member 30 provided with a liquid communication port 31 in advance. Then, the terminal 16 on the recording element substrate 10 and the terminal 41 on the flexible wiring substrate 40 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 42 on the side of the flexible wiring substrate 40 opposite to the recording element substrate 10 is electrically connected to the connection terminal 93 (see Fig. 2(a)) of the electrical wiring substrate 90. The support member 30 is a support body that supports the recording element substrate 10 and is a flow path member that fluidly communicates the recording element substrate 10 and the liquid connection portion 111. The support member 30 preferably has a high flatness and can be joined to the recording element substrate 10 with sufficiently high reliability. As the material, for example, alumina or a resin material is preferable.

[0017] (Description of the structure of the recording element substrate) The configuration of the recording element substrate 10 in the embodiment will be described. Fig. 4(a) shows a plan view of the surface of the recording element substrate 10 on which the ejection port 13 is formed, and Fig. 4(b) shows an enlarged view of the portion indicated by A in Fig. 4(a). As shown in Fig. 4(a), four rows of ejection port rows corresponding to each ink color are formed in the flow path forming member 12 of the recording element substrate 10. The direction in which the ejection port row in which a plurality of ejection ports 13 are arranged extends is referred to as the "ejection port row direction". The ejection port row direction is parallel to the plane portion of the recording element substrate 10. The ejection port row direction is the Y direction (second direction), the direction intersecting the ejection port row direction and parallel to the plane portion of the recording element substrate 10 and intersecting the ejection port row direction is the X direction (first direction), and the direction perpendicular to the plane portion of the recording element substrate 10 is the Z direction (third direction). In the embodiment, the Y direction, the X direction, and the Z direction are perpendicular to each other.

[0018] As shown in Fig. 4(b), a heating resistor 15, which is a heating element for foaming the liquid by thermal energy, is disposed at a position corresponding to each discharge port 13. A pressure chamber 23 containing the heating resistor 15 inside is partitioned by a partition wall 22. The heating resistor 15 is electrically connected to the terminal 16 in Fig. 4(a) by an electrical wiring (not shown) provided on the recording element substrate 10. The heating resistor 15 generates heat based on a pulse signal input from the control circuit of the recording apparatus 1000 via the electrical wiring substrate 90 and the flexible wiring substrate 40 (see Fig. 2), thereby boiling the liquid. The liquid is discharged from the discharge port 13 by the force of foaming due to this boiling. As shown in Fig. 4(b), along each discharge port row, a liquid supply path 18 extends on one side and a liquid recovery path 19 extends on the other side. The liquid supply path 18 and the liquid recovery path 19 are flow paths extending in the discharge port row direction (Y direction) provided on the recording element substrate 10, and communicate with the discharge port 13 via a supply port 17a and a recovery port 17b, respectively. The supply port 17a and the recovery port 17b are provided side by side in the X direction.

[0019] Next, the flow of the liquid in the recording element substrate 10 will be described. Fig. 5 is a perspective view showing a cross-section of the recording element substrate 10 and the cover plate 20 taken along the line B-B in Fig. 4(a). The recording element substrate 10 is formed by laminating a substrate 11 made of Si and a flow path forming member 12 made of a photosensitive resin, and a cover plate 20 is joined to the back surface of the substrate 11. The heating resistor 15 is formed on one surface side of the substrate 11, and grooves constituting the liquid supply path 18 and the liquid recovery path 19 extending along the discharge port row direction (Y direction) are formed on the back surface side thereof.

[0020] The liquid supply path 18 and the liquid recovery path 19 formed by the substrate 11 and the cover plate 20 are each 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 18 and the liquid recovery path 19. When liquid is discharged from a plurality of discharge ports 13 of the liquid discharge head 3 for recording, in the discharge ports 13 where the discharge operation is not being performed, due to this differential pressure, the liquid in the liquid supply path 18 provided in the substrate 11 flows into the liquid recovery path 19. The flow is a flow via the supply port 17a, the pressure chamber 23, and the recovery port 17b, and is indicated by the arrow C in FIG. 5.

[0021] Due to this flow, in the discharge ports 13 and the pressure chambers 23 where recording is paused, thickened ink generated by evaporation from the discharge ports 13, bubbles, foreign substances, etc. can be recovered into the liquid recovery path 19. Also, thickening of the ink in the discharge ports 13 and the pressure chambers 23 can be suppressed. The liquid recovered into the liquid recovery path 19 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) through the opening 21 of the cover plate 20 and the liquid communication port 31 of the support member 30 (see FIG. 3(b)). And finally, it is recovered into the supply path of the recording apparatus 1000.

[0022] (Description of the recording element substrate and the heat acting part structure) FIG. 6(a) is a plan view schematically showing an enlarged view of the vicinity of the heating resistor 15 of the recording element substrate 10. Further, FIG. 6(b) is a schematic cross-sectional view taken along the line A-A' in FIG. 6(a).

[0023] When the liquid foams, shrinks, and defoams in the region near the heating resistor 15, physical actions such as the impact due to cavitation generated at that time are exerted on the heating resistor 15. Further, when the liquid is discharged, since the heating resistor 15 is at a high temperature, chemical actions such as the thermal decomposition of the liquid components and their adhesion, fixation, and deposition on the surface of the heating resistor 15 are exerted on the heating resistor 15. In order to protect the heating resistor 15 from these physical and chemical actions on the heating resistor 15, a protective layer covering the heating resistor 15 is disposed on the heating resistor 15. The protective layer is composed of a conductive protective film 124 made of a metal film for protecting against cavitation and an insulating protective film 127 for ensuring insulation from the heating resistor 15.

[0024] With an increase in the number of discharge ports 13 or an increase in the discharge speed, the power consumption of the liquid discharge head 3 increases. In order to suppress the power consumption of the liquid discharge head 3, it is important to efficiently transfer the heat generated by the heating resistor 15 to the liquid. For this purpose, it is effective to reduce the thickness of the protective layer covering the heating resistor 15. On the other hand, a certain thickness is required to ensure the protective performance of the protective layer.

[0025] A plurality of layers are laminated on a substrate 11 formed of silicon to form a recording element substrate 10. In Example 1, an insulating layer 134 formed of a thermal oxide film, an SiO film, an SiN film, etc. is disposed on the substrate 11. Further, a heating resistor 15 is disposed on the insulating layer 134. The heating resistor 15 generates thermal energy for discharging the liquid when energized. The insulating layer 134 serves as a heat storage layer for storing the heat generated from the heating resistor 15.

[0026] An insulating protective film 127 made of an insulator is disposed on the heating resistor 15 and covers the heating resistor 15. The insulating protective film 127 is provided above these so as to cover the heating resistor 15. The insulating protective film 127 is formed of an SiO film, an SiN film, etc. The insulating protective film 127 is required to be thin from the viewpoint of the thermal efficiency of foaming, and a thickness of 100 to 300 nm is preferable.

[0027] On the insulating protective film 127, a conductive protective film 124 made of a conductor is disposed, covering the insulating protective film. The conductive protective film 124 protects the surface of the heating resistor 15 from chemical and physical impacts associated with the heat generation of the heating resistor 15. The conductive protective film 124 is preferably formed of a film having cavitation resistance such as iridium (Ir) or tantalum (Ta) to a thickness of about 50 to 300 nm.

[0028] In the insulating layer 134, a first electrical wiring 129a to which a first voltage is applied and a second electrical wiring 129b to which a second voltage is applied are embedded. The first electrical wiring 129a and the second electrical wiring 129b are formed of a metal material such as Al, Al-Si, or Al-Cu. The first voltage applied to the first electrical wiring 129a is higher than the second voltage applied to the second electrical wiring 129b. The first voltage applied to the first electrical wiring 129a is the power supply voltage, and the second voltage applied to the second electrical wiring 129b is the ground voltage. Therefore, the first electrical wiring 129a is the electrical wiring on the high potential side, and the second electrical wiring 129b is the electrical wiring on the low potential side. Also, in the insulating layer 134, a heat sink 126 is formed in the same layer as the first electrical wiring 129a and the second electrical wiring 129b in order to efficiently release the generated heat. The thickness of the insulating layer 134 is preferably about 1 to 3 μm.

[0029] In the insulating layer 134, a first electrode plug 128a and a second electrode plug 128b are embedded so as to be in contact with the lower surface of the heating resistor 15. The first electrode plug 128a is a first connection member that electrically connects the heating resistor 15 and the first electrical wiring 129a, and is a connection member on the high potential side. The second electrode plug 128b is a second connection member that electrically connects the heating resistor 15 and the second electrical wiring 129b, and is a connection member on the low potential side. The first electrode plug 128a and the second electrode plug 128b are formed of tungsten, copper, or an alloy thereof. The first electrode plug 128a and the second electrode plug 128b are electrode plugs extending in the Z direction orthogonal to the surface of the substrate 11 on which the heating resistor 15 is provided. The first electrode plug 128a and the second electrode plug 128b are located on opposite sides of the heating resistor 15 in the X direction parallel to the surface of the substrate 11 on which the heating resistor 15 is provided.

[0030] As shown in FIG. 6(a), a supply port 17a for supplying liquid and a recovery port 17b for recovering liquid are formed on both sides of the heating resistor 15 in the recording element substrate 10, and further, a discharge port 13 and a flow path forming member 12 are formed. The flow path forming member 12 is located on the substrate 11 as shown in FIG. 5 with the insulating layer 134 interposed therebetween, forms a flow path through which the liquid flows, and has a discharge port 13 located on the opposite side with the insulating layer 134 and the flow path interposed therebetween. The heating resistor 15 is provided so as to face the discharge port 13.

[0031] A first connection region 138a extending along the Y direction is located at one end of the heating resistor 15 in the X direction, and a second connection region 138b extending along the second direction is located at the other end. The first electrode plug 128a is connected to the heating resistor 15 in the first connection region 138a, and the second electrode plug 128b is connected to the heating resistor 15 in the second connection region 138b.

[0032] In Example 1, the X direction is the first direction parallel to the surface of the substrate 11 on which the heating resistor 15 is provided. The Y direction is the second direction parallel to the surface of the substrate 11 on which the heating resistor 15 is provided and intersecting the first direction. The Z direction is the third direction perpendicular to the surface of the substrate 11 on which the heating resistor 15 is provided.

[0033] (Description of the electrode plug) FIG. 7(a) is a top view of the vicinity of the heating resistor 15 of the recording element substrate 10 of Example 1, and FIG. 7(b) shows a schematic cross-sectional view of the vicinity of the heating resistor 15 along the line B-B' in FIG. 7(a).

[0034] In the recording element substrate 10 of Example 1, the shapes of the first electrode plug 128a and the second electrode plug 128b are different. As shown in FIG. 7(a), a first connection region 138a to which the first electrode plug 128a is connected and a second connection region 138b to which the second electrode plug 128b is connected extend along the Y direction in the vicinity of both end portions in the X direction with the discharge port 13 of the heating resistor 15 interposed therebetween.

[0035] The first electrode plug 128a is composed of a plurality of first connection portions 1280a arranged along the Y direction in the first connection region 138a. In Example 1, the first connection portion 1280a is a columnar plug having a substantially circular cross-section perpendicular to the Z direction and a diameter smaller than the length of the first connection region 138a in the Y direction. Each of the first connection portions 1280a can be formed, for example, by embedding a conductive material in a hole having a width of 1 μm or less in the X direction.

[0036] The second electrode plug 128b consists of one second connection portion 1280b extending in the Y direction in the second connection region 138b. In Example 1, the second connection portion 1280b has an oval cross-section perpendicular to the Z direction, and the length along the Y direction thereof is approximately the same as the length in the Y direction of the second connection region 138b. The width of the second connection portion 1280b in the X direction is approximately the same as the width of the first connection portion 1280a in the X direction. The second connection portion 1280b can be formed, for example, by embedding a conductive material in a slit extending in the Y direction with a width of 1 μm or less in the X direction. The second connection portion 1280b is continuously arranged over substantially the entire Y direction of the second connection region 138b.

[0037] In Example 1, the volume of each of the plurality of first connection portions 1280a is smaller than the volume of the second connection portion 1280b. Also, the volume of the first electrode plug 128a is smaller than the volume of the second electrode plug 128b. The volume of the first electrode plug 128a is the sum of the volumes of the plurality of first connection portions 1280a, and the volume of the second electrode plug 128b is the volume of the second connection portion 1280b. In Example 1, the thickness of the first electrode plug 128a in the Z direction is equal to the thickness of the second electrode plug 128b in the Z direction. Therefore, the cross-sectional area of each of the plurality of first connection portions 1280a by a plane perpendicular to the Z direction is smaller than the cross-sectional area of the second connection portion 1280b by a plane perpendicular to the Z direction. Also, the cross-sectional area of the first electrode plug 128a by a plane perpendicular to the Z direction is smaller than the cross-sectional area of the second electrode plug 128b by a plane perpendicular to the Z direction. Here, the cross-sectional area of the first electrode plug 128a is the sum of the cross-sectional areas of the plurality of first connection portions 1280a, and the cross-sectional area of the second electrode plug 128b is the cross-sectional area of one second connection portion 1280b. Also, in Example 1, the width of the first electrode plug 128a in the X direction is equal to the width of the second electrode plug 128b in the X direction. Therefore, the length of each of the plurality of first connection portions 1280a in the Y direction is shorter than the length of the second connection portion 1280b in the Y direction. Also, the length of the first electrode plug 128a in the Y direction is shorter than the length of the second electrode plug 12 8b in the Y direction. The length of the first electrode plug 128a in the Y direction is the sum of the lengths of the plurality of first connection portions 1280a in the Y direction. The length of the second electrode plug 128b in the Y direction is the length of one second connection portion 1280b in the Y direction.

[0038] In the following description, when the first electrode plug 128a and the second electrode plug 128b are not distinguished, they may be simply referred to as the electrode plug 128. Also, when the first electrical wiring 129a and the second electrical wiring 129b are not distinguished, they may be simply referred to as the electrical wiring 129.

[0039] The heating resistor 15 is connected to the electrical wiring 129 by the electrode plug 128. The electrode plug 128 is formed of a material capable of forming an embedded electrode such as tungsten or copper. In Example 1, tungsten was used for the electrode plug 128. An insulating layer 134 composed of an insulator having a thickness of about 2 μm in the Z direction is provided under the heating resistor 15.

[0040] The electrode plug 128 is formed by forming a through-hole in the insulating layer 134 and embedding the material of the electrode plug 128 in the through-hole. The ratio of the thickness of the insulating layer in which the electrode plug is formed to the through-hole diameter is called the aspect ratio. When the through-hole extends in the longitudinal direction in a rectangular or oval slit shape, the ratio of the thickness of the insulating layer to the width in the short direction of the slit shape is defined as the aspect ratio. The smaller the through-hole diameter, the larger the aspect ratio, and the thinner the slit shape, the larger the aspect ratio. Since the electrode plug 128 is formed in a thin columnar or slit shape, the aspect ratio (layer thickness of the insulating layer 134 / through-hole diameter) is large. Also, since the film thickness of the heating resistor 15 on the electrode plug 128 is thin, unlike the commonly used aluminum wiring, the shape of the electrode plug 128 becomes important.

[0041] The voids generated in the formation process of the electrode plug 128 will be described with reference to FIGS. 8(a) to 8(d).

[0042] After forming the electrical wiring 129 and the heat sink 126 on the substrate 11 (see Fig. 6(b)), an interlayer insulating layer 137 made of SiO is formed thereon, and the outermost layer is planarized by the CMP method (Chemical Mechanical Polishing) (not shown). The interlayer insulating layer 137 on the electrical wiring 129 and the heat sink 126 becomes the insulating layer 134 in the recording element substrate 10. After that, as shown in Fig. 8(a), the interlayer insulating layer 137 and the through hole 135 are patterned.

[0043] As shown in Fig. 8(b), thereafter, a barrier metal layer 130 made of TiN / Ti is formed on the inner wall surface of the through hole 135 and the surface of the interlayer insulating layer by sputtering. Thereafter, a tungsten film 131 is formed by the CVD method (Chemical Vapor Deposition) so as to fill the through hole 135.

[0044] At this time, voids 132, which are cavity regions, may be generated in the through hole 135. Then, when removing the tungsten formed on the surface layer in the CMP process, as shown in Fig. 8(c), the voids 132 may appear on the outermost layer. Then, a seam 133, which is a hole, may be opened on the outermost layer, and the shape may become uneven.

[0045] Thereafter, a heating resistor 15 made of TaSiN with a thickness of 10 to 20 nm is formed so as to cover the through hole 135 serving as an electrode plug. Thereafter, an insulating protective film 127 made of 200 nm of silicon nitride (SiN) is formed using the CVD method, and further, a conductive protective film 124 made of tantalum (Ta) is formed with a thickness of 200 nm using the sputtering method, and patterning is performed in a predetermined pattern.

[0046] When the heating resistor 15 or the protective layer is formed in a state where irregularities exist on the surface of the electrode plug due to the presence of the seam 133, as shown in Fig. 8(d), the insulating protective film 127 may not be able to cover the seam 133 region. In this case, an electrical short may occur between the heating resistor 15 and the conductive protective film 124.

[0047] Void 132 is likely to occur when the diameter of the through hole 135 is small and the aspect ratio is large. In particular, when the diameter of the through hole 135 is less than 0.5 μm (and the aspect ratio is greater than 4), the seam 133 becomes large, and there is a tendency for the short circuit between the heating resistor 15 and the conductive protective film 124 to increase. Although it is possible to detect this short circuit by inspection, the yield will decrease.

[0048] By increasing the diameter of the through hole 135 and decreasing the aspect ratio, the generation of void 132 can be suppressed. Also, by making the through hole 135 in a slit shape or increasing the through hole 135 to increase the volume of the electrode plug, the generation of void 132 can be suppressed. Thereby, the embedding characteristics of the tungsten film 131 by the CVD method can be improved, and the short circuit between the heating resistor 15 and the conductive protective film 124 can be suppressed. It is desirable that the diameter of the through hole 135 be 0.6 μm or more. In particular, it is desirable that the diameter of the through hole 135 be 1.0 μm or more.

[0049] (Behavior at accidental disconnection due to electrode plug shape) FIG. 9 is a diagram showing a state when the heating resistor 15 is accidentally disconnected. FIG. 9(a) shows a schematic top view of the vicinity of the heating resistor 15. FIG. 9(b) shows a schematic cross-sectional view taken along the line C-C' of FIG. 9(a) in FIG. 9(b). Here, a case where both the first electrode plug 128c and the second electrode plug 128d have a large-volume slit shape will be described as an example.

[0050] An accidental disconnection of the heating resistor 15 is caused, for example, by an abnormal heat generation of the heating resistor 15, which reduces the insulation of the insulating protective film 127, and an insulation breakdown of the insulating protective film 127 occurs in a region where the potential difference between the ground potential and the conductive protective film 124 is maximized. FIG. 9 illustrates a case where a disconnection of the heating resistor 15 occurs near the first electrode plug 128c. As shown in FIG. 9(b), when a disconnection of the heating resistor 15 occurs near the first electrode plug 128c, the portion from the upper part of the first electrode plug 128a to the conductive protective film 124 may be blown away toward the pressure chamber by the impact. In this case, as shown in FIG. 9(a), a damage region 136 where the insulating protective film 127 and the conductive protective film 124 are blown away toward the pressure chamber 23 side is generated around the first electrode plug 128c.

[0051] At this time, when the volume of the first electrode plug 128c is large like a slit-shaped electrode plug, a part of the first electrode plug 128c may remain without being blown away even by the impact during accidental disconnection. Then, a short circuit occurs between the heating resistor 15 and the conductive protective film 124, and the conductive protective film 124 is pulled to the potential applied to the heating resistor 15 and becomes a high potential. Therefore, anodic oxidation or elution into the ink may occur due to the electrochemical reaction between the conductive protective film 124 and the ink.

[0052] In addition, when there is a portion of the heating resistor 15 that is not covered by the conductive protective film 124 and the insulating protective film 127, a liquid such as ink may reach the heating resistor 15. In this case, a potential difference is generated between the positive potential electrode plug 128 and the liquid at the ground potential through the heating resistor 15 during the operation of the heating resistor 15. Due to this potential difference, the conductive protective film 124 and the insulating protective film 127 may be dissolved by the action of electrolysis, and the durability of the recording element substrate 10 may be reduced.

[0053] On the other hand, when the volume of the electrode plug is small like a columnar electrode plug or when the through-hole diameter is small, when a disconnection of the heating resistor 15 occurs, the electrode plug 128 and the conductive protective film 12 The probability of short - circuiting between 4 is low. In particular, when the through - hole diameter of the electrode plug 128 is less than 1 μm, it is difficult for a short - circuit to occur even when the heating resistor 15 is subjected to an impact due to a broken wire.

[0054] Also, in the second electrode plug 128d, even if an accidental disconnection occurs in the heating resistor 15, it is difficult for a phenomenon in which the second electrode plug 128d, the insulating protective film 127, or the conductive protective film 124 is blown off to occur due to this.

[0055] From the above, in the electrode plug 128 on the high - potential side where there is a possibility of short - circuit when an accidental disconnection of the heating resistor 15 occurs, in order to suppress the short - circuit at the time of disconnection, it is desirable to reduce the volume of the electrode plug and reduce the through - hole diameter. For example, it is desirable that the electrode plug on the high - potential side has a columnar shape with a through - hole diameter less than 1 μm.

[0056] On the other hand, in the electrode plug 128 on the low - potential side where the possibility of short - circuit is low when an accidental disconnection of the heating resistor 15 occurs, in order to suppress the generation of voids, it is desirable to increase the volume of the electrode plug and increase the through - hole diameter. For example, it is desirable that the electrode plug on the low - potential side has a slit shape with a width of 1.0 μm or more.

[0057] Hereinafter, examples and comparative examples will be described using cross - sectional views and top views.

[0058] FIG. 10(a) and FIG. 10(b) are top views of Comparative Example 1 and Comparative Example 2, respectively, and FIG. 10(c) and FIG. 10(d) are top views of Example 1 and Example 2, respectively. The cross - sectional view will be described with reference to FIG. 7(b).

[0059] As the insulating layer 134 under the heating resistor 15, SiO with a thickness of 2 μm was formed. The upper surface of the insulating layer 134 was planarized by the CMP method. The foaming region of the heating resistor 15 was sized 15 μm × 15 μm, and both ends in the X direction were connected to the electrode plug on the high potential side and the electrode plug on the low potential side, respectively. The electrode plug on the high potential side and the electrode plug on the low potential side were formed simultaneously in the same process. A 200-nm insulating protective film 127 made of SiN was formed on the heating resistor 15, and further, a 100-nm conductive protective film 124 made of Ta was formed on the insulating protective film 127.

[0060] The seam shape when forming the electrode plug 128 was evaluated. Also, the occurrence probability of a short circuit between the heating resistor 15 and the conductive protective film 124 when a long pulse was applied to the heating resistor 15 to force disconnection was evaluated.

[0061] (Comparative Example 1) Figure 10(a) shows a top view of the vicinity of the heating resistor 15 in Comparative Example 1. Comparative Example 1 is an example in which both the first connection portion 1280a of the first electrode plug 128a and the second connection portion 1280d of the second electrode plug 128f are columnar. In Comparative Example 1, both the first connection portion 1280a and the second connection portion 1280f had a through-hole diameter of 1 μm, and seven electrode plugs were arranged at intervals of 1 μm in the Y direction.

[0062] In this case, some of the first electrode plug 128a and the second electrode plug 128f had a seam 133 of about 0.1 μm in a part of the first connection portion 1280a and the second connection portion 1280f. There was no significant decrease in the coverage of the insulating protective film 127 on the electrode plug 128. However, the yield may decrease.

[0063] On the other hand, when a long pulse was applied to the heating resistor 15 to cause disconnection, although damage occurred near the conductive protective film 124 in a part of the first connection portion 1280a of the first electrode plug 128a, a short circuit between the heating resistor 15 and the conductive protective film 124 did not occur.

[0064] (Comparative Example 2) FIG. 10(b) shows a top view of the vicinity of the heating resistor 15 of Comparative Example 2. Comparative Example 2 is an example in which both the first connection portion 1280c of the first electrode plug 128c and the second connection portion 1280d of the second electrode plug 128d are slit-shaped. In Comparative Example 2, both the first connection portion 1280c and the second connection portion 1280d had a slit width of 1 μm and a slit length of 13 μm.

[0065] In this case, there was no seam in both the first electrode plug 128c and the second electrode plug 128d, and the shape on the electrode plug 128 was stable.

[0066] On the other hand, when a long pulse was applied to the heating resistor 15 to cause disconnection, damage occurred near the conductive protective film 124 in a part of the first connection portion 1280c of the first electrode plug 128c. And a short circuit occurred between the heating resistor 15 and the conductive protective film 124 at a ratio of about 1% with respect to the total number of the disconnected heating resistors 15.

[0067] (Example 1) FIG. 10(c) shows a top view of the vicinity of the heating resistor 15 of Example 1. In Example 1, the first electrode plug 128a has a configuration in which a plurality of first connection portions 1280a (columnar plugs) are arranged in the Y direction, and the second electrode plug 128b has a configuration consisting of one second connection portion 1280b (slit-shaped plug) extending in the Y direction. In Example 1, the first connection portion 1280a had a through-hole diameter of 1 μm and seven were arranged at intervals of 1 μm in the Y direction. The second connection portion 1280b had a slit width of 1 μm and a slit length of 13 μm.

[0068] In this case, regarding the first electrode plug 128a, some of the first connection portions 1280a had a seam of about 0.1 μm. Regarding the second electrode plug 128b, there was no seam and the shape was stable.

[0069] On the other hand, when a long pulse was applied to the heating resistor 15 to cause disconnection, damage occurred near the conductive protective film 124 in a part of the first connection portion 1280a of the first electrode plug 128a, but a short circuit did not occur between the heating resistor 15 and the conductive protective film 124.

[0070] Therefore, in Example 1, regarding the first electrode plug 128a, although there is a possibility of some shape instability due to the seam, the reliability at the time of disconnection of the heating resistor 15 was improved. Regarding the second electrode plug 128b, the shape was stable, and it was predicted that the yield would be improved compared to Comparative Example 1.

[0071] (Example 2) FIG. 10(d) shows a top view of the vicinity of the heating resistor 15 in Example 2. The first electrode plug 128a is composed of a plurality of first connection portions 1280a arranged along the Y direction in the first connection region 138a. The configuration of the first connection portion 1280a is the same as that in Example 1. The second electrode plug 128e is composed of a plurality of second connection portions 1280e arranged along the Y direction in the second connection region 138b. In Example 2, the second connection portion 1280e has an oval cross section perpendicular to the Z direction, and the length along the Y direction is shorter than the length in the Y direction of the second connection region 138b. The width of the second connection portion 1280e in the X direction is about the same as the width of the first connection portion 1280a in the X direction. The second connection portion 1280e can be formed, for example, by embedding a conductive material in a slit having a width of 1 μm or less in the X direction and extending in the Y direction. In Example 2, the through-hole diameter of the first connection portion 1280a was 1 μm, and seven were arranged at intervals of 1 μm in the Y direction. The second connection portion 1280e had a slit width of 1 μm and a slit length of 3 μm, and three were arranged at intervals of 2 μm in the Y direction.

[0072] In Example 2, the volume of each of the plurality of first connection portions 1280a is the plurality of second connection portions 128 It is smaller than the volume of 0e. Also, the volume of the first electrode plug 128a is smaller than the volume of the second electrode plug 128e. The volume of the first electrode plug 128a is the sum of the volumes of the plurality of first connection parts 1280a, and the volume of the second electrode plug 128e is the sum of the volumes of the plurality of second connection parts 1280e. In Example 2, the thickness of the first electrode plug 128a in the Z direction is equal to the thickness of the second electrode plug 128e in the Z direction. Therefore, the cross-sectional area of each of the plurality of first connection parts 1280a by a plane perpendicular to the Z direction is smaller than the cross-sectional area of each of the plurality of second connection parts 1280e by a plane perpendicular to the Z direction. Also, the cross-sectional area of the first electrode plug 128a by a plane perpendicular to the Z direction is smaller than the cross-sectional area of the second electrode plug 128b by a plane perpendicular to the Z direction. Here, the cross-sectional area of the first electrode plug 128a is the sum of the cross-sectional areas of the plurality of first connection parts 1280a, and the cross-sectional area of the second electrode plug 128b is the sum of the cross-sectional areas of the plurality of second connection parts 1280e. Also, in Example 2, the width of the first electrode plug 128a in the X direction is equal to the width of the second electrode plug 128e in the X direction. Therefore, the length of each of the plurality of first connection parts 1280a in the Y direction is shorter than the length of each of the plurality of second connection parts 1280e in the Y direction. Also, the length of the first electrode plug 128a in the Y direction is shorter than the length of the second electrode plug 128e in the Y direction. The length of the first electrode plug 128a in the Y direction is the sum of the lengths of the plurality of first connection parts 1280a in the Y direction. The length of the second electrode plug 128e in the Y direction is the length of the plurality of second connection parts 1280e in the Y direction. Also, the length of each of the plurality of first connection parts 1280a in the Y direction is shorter than the length of each of the plurality of second connection parts 1280e in the Y direction. And the number of the first connection parts 1280a is larger than the number of the second connection parts 1280e.

[0073] In this case, regarding the first electrode plug 128a, some of the first connection parts 1280a had a seam of about 0.1 μm. Regarding the second electrode plug 128e, there was no seam and the shape was stable.

[0074] On the other hand, when a long pulse was applied to the heating resistor 15 to cause disconnection, damage occurred near the conductive protective film 124 in a part of the first connection portion 1280a of the first electrode plug 128a, but no short circuit occurred between the heating resistor 15 and the conductive protective film 124.

[0075] Therefore, in Example 2, regarding the first electrode plug 128a, although there is a possibility of some shape instability due to the seam, the reliability during disconnection of the heating resistor 15 was improved. Regarding the second electrode plug 128e, the shape was stable, and it was predicted that the yield would be improved as compared with Comparative Example 1.

[0076] As described above, by adopting the electrode plug 128 described in this embodiment, it is possible to improve the yield due to the formation defect of the electrode plug 128 without increasing the probability of failure during accidental disconnection.

[0077] Note that the present invention includes the method for manufacturing the recording element substrate described in the above embodiment. For example, first, a step of forming an insulating layer 134 in which a first electrical wiring 129a to which a first voltage is applied and a second electrical wiring 129b to which a second voltage is applied are embedded on the substrate 11 is performed. Next, a first connection portion 1280a is formed in the insulating layer 134.

[0078] The disclosure of this embodiment includes the following configurations. (Configuration 1) A substrate, An insulating layer located on the substrate, A heating resistor located on the insulating layer, which generates heat energy for discharging a liquid when energized, An insulating protective film made of an insulator covering the heating resistor, A conductive protective film made of a conductor covering the insulating protective film, A first electrical wiring embedded in the insulating layer, A second electrical wiring embedded in the insulating layer, A first connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the first connection member electrically connecting the heating resistor and the first electrical wiring; A second connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the second connection member electrically connecting the heating resistor and the second electrical wiring; A recording element substrate having: The recording element substrate, wherein the volume of the first connection member on the high potential side among the first connection member and the second connection member is smaller than the volume of the second connection member on the low potential side. (Configuration 2) The recording element substrate according to Configuration 1, wherein the first connection member and the second connection member are located on opposite sides of the heating resistor across the heating resistor in a first direction parallel to the surface of the substrate on which the heating resistor is provided. (Configuration 3) When a direction parallel to the surface of the substrate on which the heating resistor is provided and intersecting the first direction is defined as a second direction, and a direction perpendicular to the surface of the substrate on which the heating resistor is provided is defined as a third direction, The recording element substrate according to Configuration 2, wherein a cross-sectional area of the first connection member by a plane perpendicular to the third direction is smaller than a cross-sectional area of the second connection member by a plane perpendicular to the third direction. (Configuration 4) When a direction parallel to the surface of the substrate on which the heating resistor is provided and intersecting the first direction is defined as a second direction, The recording element substrate according to Configuration 2 or 3, wherein a length of the first connection member in the second direction is shorter than a length of the second connection member in the second direction. (Configuration 5) When a direction parallel to the surface of the substrate on which the heating resistor is provided and intersecting the first direction is defined as a second direction, The first connection member is connected to the heating resistor in a first connection region located at one end of the heating resistor in the first direction and extending along the second direction, The second connection member is connected to the heating resistor in a second connection region located at the other end of the heating resistor in the first direction and extending along the second direction, The first connection member includes a plurality of first connections arranged along the second direction in the first connection region. The second connection member includes one second connection extending along the second direction in the second connection region. The recording element substrate according to any one of Configurations 2 to 4. (Configuration 6) The recording element substrate according to Configuration 5, wherein the volume of each of the plurality of first connections is smaller than the volume of the second connection. (Configuration 7) Taking the direction perpendicular to the surface of the substrate where the heating resistor is provided as the third direction, The recording element substrate according to Configuration 5 or 6, wherein the cross-sectional area of each of the plurality of first connections by a plane perpendicular to the third direction is smaller than the cross-sectional area of the second connection by a plane perpendicular to the third direction. (Configuration 8) The recording element substrate according to any one of Configurations 5 to 7, wherein the length of each of the first connections in the second direction is shorter than the length of the second connection in the second direction. (Configuration 9) Taking the direction parallel to the surface of the substrate where the heating resistor is provided and intersecting the first direction as the second direction, The first connection member is connected to the heating resistor in a first connection region at one end of the heating resistor in the first direction, The second connection member is connected to the heating resistor in a second connection region at the other end of the heating resistor in the first direction, The first connection member includes a plurality of first connections arranged along the second direction in the first connection region. The second connection member includes a plurality of second connections arranged along the second direction in the second connection region. The recording element substrate according to any one of Configurations 2 to 4. (Configuration 10) The recording element substrate according to Configuration 9, wherein the volume of each of the plurality of first connections is smaller than the volume of each of the plurality of second connections. (Configuration 11) ​Taking the direction perpendicular to the surface of the substrate where the heating resistor is provided as the third direction, The recording element substrate according to configuration 9 or 10, wherein the cross-sectional area of each of the plurality of first connection portions in a plane perpendicular to the third direction is smaller than the cross-sectional area of each of the plurality of second connection portions in a plane perpendicular to the third direction. (Configuration 12) The recording element substrate according to any one of configurations 9 to 11, wherein the length of each of the plurality of first connection portions in the second direction is shorter than the length of each of the plurality of second connection portions in the second direction. (Configuration 13) The recording element substrate according to any one of configurations 9 to 12, wherein the number of the first connection portions is larger than the number of the second connection portions. (Configuration 14) The recording element substrate according to any one of configurations 5 to 13, wherein the first connection portion is formed in a hole having a width of 1 μm or less in the first direction. (Configuration 15) The recording element substrate according to any one of configurations 5 to 14, wherein the second connection portion is formed in a slit extending in the second direction. (Configuration 16) The recording element substrate according to any one of configurations 1 to 15, wherein the first connection member and the second connection member are electrode plugs extending in a third direction perpendicular to the surface of the substrate where the heating resistor is provided. (Configuration 17) The recording element substrate according to any one of configurations 1 to 16, wherein the first connection member and the second connection member are formed of tungsten, copper, or an alloy thereof. (Configuration 18) A flow path member located on the insulating layer, which forms a flow path through which a liquid flows and has a discharge port located on the opposite side across the insulating layer and the flow path, The recording element substrate according to any one of configurations 1 to 17, wherein the heating resistor is provided so as to face the discharge port. (Configuration 19) A substrate, An insulating layer located on the substrate, A heating resistor located on the insulating layer, the heating resistor generating thermal energy for discharging a liquid when energized. An insulating protective film made of an insulator covering the heating resistor. A conductive protective film made of a conductor covering the insulating protective film. A first electrical wiring embedded in the insulating layer. A second electrical wiring embedded in the insulating layer. A first connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the first connection member electrically connecting the heating resistor and the first electrical wiring. A second connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the second connection member electrically connecting the heating resistor and the second electrical wiring. A recording element substrate having the above. A recording element substrate, characterized in that the cross-sectional area of the first connection member on the high potential side among the first connection member and the second connection member, taken by a plane perpendicular to the direction perpendicular to the surface of the substrate on which the heating resistor is provided, is smaller than the cross-sectional area of the second connection member on the low potential side taken by the perpendicular plane. (Configuration 20) A recording apparatus having the recording element substrate according to any one of Configurations 1 to 19, and performing recording with a liquid discharged from the recording element substrate by the thermal energy generated by the heating resistor.

Explanation of Reference Numerals

[0079] 11: Substrate, 15: Heating resistor, 10: Recording element substrate, 124: Conductive protective film, 127: Insulating protective film, 128a: First electrode plug, 128b: Second electrode plug, 129a: First electrical wiring, 129b: Second electrical wiring, 134: Insulating layer

Claims

1. A substrate, an insulating layer located on the substrate, a heating resistor located on the insulating layer, which generates thermal energy for discharging a liquid when energized, an insulating protective film made of an insulator covering the heating resistor, a conductive protective film made of a conductor covering the insulating protective film, a first electrical wiring embedded in the insulating layer, a second electrical wiring embedded in the insulating layer, a first connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, which electrically connects the heating resistor and the first electrical wiring, a second connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, which electrically connects the heating resistor and the second electrical wiring, A recording element substrate having: The recording element substrate is characterized in that the volume of the first connection member on the high potential side among the first connection member and the second connection member is smaller than the volume of the second connection member on the low potential side.

2. The recording element substrate according to claim 1, wherein the first connection member and the second connection member are located on opposite sides of each other with the heating resistor interposed therebetween in a first direction parallel to the surface of the substrate on which the heating resistor is provided.

3. When a direction parallel to the surface of the substrate on which the heating resistor is provided and intersecting the first direction is defined as a second direction, and a direction perpendicular to the surface of the substrate on which the heating resistor is provided is defined as a third direction, The recording element substrate according to claim 2, wherein a cross-sectional area of the first connection member by a plane perpendicular to the third direction is smaller than a cross-sectional area of the second connection member by a plane perpendicular to the third direction.

4. When a direction parallel to the surface of the substrate on which the heating resistor is provided and intersecting the first direction is defined as a second direction, The recording element substrate according to claim 2, wherein a length of the first connection member in the second direction is shorter than a length of the second connection member in the second direction.

5. When a direction parallel to the surface of the substrate on which the heating resistor is provided and intersecting the first direction is defined as a second direction, The first connection member is connected to the heating resistor in a first connection region located at one end of the heating resistor in the first direction and extending along the second direction, The second connection member is connected to the heating resistor in a second connection region located at the other end of the heating resistor in the first direction and extending along the second direction, The first connection member includes a plurality of first connection portions arranged along the second direction in the first connection region. The recording element substrate according to claim 2, wherein the second connection member includes one second connection portion extending in the second direction in the second connection region.

6. The recording element substrate according to claim 5, wherein the volume of each of the plurality of first connection portions is smaller than the volume of the second connection portion.

7. Taking the direction perpendicular to the surface of the substrate where the heating resistor is provided as the third direction, The recording element substrate according to claim 5, wherein the cross-sectional area of each of the plurality of first connection portions by a plane perpendicular to the third direction is smaller than the cross-sectional area of the second connection portion by a plane perpendicular to the third direction.

8. The recording element substrate according to claim 5, wherein the length of each of the first connection portions in the second direction is shorter than the length of the second connection portion in the second direction.

9. Taking the direction parallel to the surface of the substrate where the heating resistor is provided and intersecting the first direction as the second direction, The first connection member is connected to the heating resistor in a first connection region at one end of the heating resistor in the first direction. The second connection member is connected to the heating resistor in a second connection region at the other end of the heating resistor in the first direction. The first connection member includes a plurality of first connection portions arranged along the second direction in the first connection region. The recording element substrate according to claim 2, wherein the second connection member includes a plurality of second connection portions arranged along the second direction in the second connection region.

10. The recording element substrate according to claim 9, wherein the volume of each of the plurality of first connection portions is smaller than the volume of each of the plurality of second connection portions.

11. Taking the direction perpendicular to the surface of the substrate where the heating resistor is provided as the third direction, The recording element substrate according to claim 9, wherein the cross-sectional area of each of the plurality of first connection portions by a plane perpendicular to the third direction is smaller than the cross-sectional area of each of the plurality of second connection portions by a plane perpendicular to the third direction.

12. The recording element substrate according to claim 9, wherein the length of each of the plurality of first connection portions in the second direction is shorter than the length of each of the plurality of second connection portions in the second direction.

13. The recording element substrate according to claim 9, wherein the number of the first connection portions is larger than the number of the second connection portions.

14. The recording element substrate according to any one of claims 5 to 13, wherein the first connection portion is formed in a hole having a width in the first direction of 1 μm or less.

15. The recording element substrate according to any one of claims 5 to 13, wherein the second connection portion is formed in a slit extending in the second direction.

16. The recording element substrate according to any one of claims 1 to 13, wherein the first connection member and the second connection member are electrode plugs extending in a third direction orthogonal to the surface of the substrate on which the heating resistor is provided.

17. The recording element substrate according to any one of claims 1 to 13, wherein the first connection member and the second connection member are formed of tungsten, copper, or an alloy thereof.

18. A flow path member located above the insulating layer, the flow path member forming a flow path through which a liquid flows and having a discharge port located on the opposite side of the insulating layer with the flow path therebetween, The recording element substrate according to any one of claims 1 to 13, wherein the heating resistor is provided so as to face the discharge port.

19. A substrate, An insulating layer located above the substrate, A heating resistor located above the insulating layer, the heating resistor generating thermal energy for discharging a liquid when energized, An insulating protective film made of an insulator covering the heating resistor, A conductive protective film made of a conductor covering the insulating protective film, A first electrical wiring embedded in the insulating layer, A second electrical wiring embedded in the insulating layer, A first connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the first connection member electrically connecting the heating resistor and the first electrical wiring, A second connection member embedded in the insulating layer so as to contact the lower surface of the heating resistor, the second connection member electrically connecting the heating resistor and the second electrical wiring, A recording element substrate having, The cross-sectional area of the first connection member on the high-potential side of the first connection member and the second connection member in a plane perpendicular to the direction orthogonal to the surface of the substrate on which the heating resistor is provided is smaller than the cross-sectional area of the second connection member on the low-potential side in the perpendicular plane. The recording element substrate is characterized by this.

20. A recording apparatus having the recording element substrate according to any one of claims 1 to 13, 19, and performing recording with a liquid discharged from the recording element substrate by thermal energy generated by the heating resistor.

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