Liquid ejection chip, wafer for liquid ejection, and method for manufacturing liquid ejection chip

Abstract

To provide a liquid ejection chip which inhibits deterioration of the yield.SOLUTION: In a liquid ejection chip, a first flow channel substrate having an energy generation element configured to generate energy for ejecting a liquid, and a first flow channel configured to supply the liquid to the energy generation element and a second flow channel substrate having a second flow channel connecting to the first flow channel are bonded to each other through an adhesive. Recessed portions are formed at each of a wall surface of the first flow channel and a wall surface of the second flow channel. In terms of at least one of depth and width of the recessed portions, the first flow channel substrate>the second flow channel substrate is satisfied.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection chip, a wafer for liquid ejection, and a method for manufacturing a liquid ejection chip.

Background Art

[0002] MEMS (Micro Electro Mechanical Systems) devices are fabricated by joining members in which grooves or through-holes serving as flow paths are formed. As an example of an MEMS device, a liquid ejection chip that ejects liquid onto a recording medium is known.

[0003] The liquid ejection chip includes an energy generating element that gives energy for ejecting liquid. Examples of the energy generating element include an element that heats and boils liquid, such as a heater element, or an element that applies pressure to liquid by utilizing volume change, such as a piezo element.

[0004] Flow paths for supplying liquid to the energy generating element are known, which are formed by laminating a plurality of members in which grooves or holes serving as flow paths are formed, and those in which grooves or holes serving as flow paths are formed after lamination. The lamination of these members is performed by bonding via an adhesive.

[0005] Also, a plurality of these MEMS devices are formed on a substrate called a wafer, and the substrate is cut and divided into a plurality of liquid ejection chips. As a method for cutting the substrate, there is a method called laser stealth dicing. In this method, the inside is altered by condensing laser light inside the substrate, and the substrate is cut by applying an external force to the substrate to continue cracks starting from the altered part (hereinafter referred to as dicing).

[0006] Patent Document 1 discloses a technique of forming a groove on a planned cutting line inclined with respect to the crystal orientation of the substrate in order to improve the cutting accuracy during dicing.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] When forming a groove on the planned cutting line using the technology of Patent Document 1, the adhesive may flow into the groove on the planned cutting line or into the flow path or the like. And after the chip is cut, a lump of the adhesive may remain, which may reduce the yield.

[0009] An object of the present disclosure is to provide a liquid ejection chip in which a decrease in yield is suppressed.

Means for Solving the Problems

[0010] A liquid ejection chip according to an aspect of the present disclosure includes a first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element, and a second flow path substrate having a second flow path connected to the first flow path, which are joined via an adhesive. In the liquid ejection chip, recesses are formed on the wall surface of the first flow path and the wall surface of the second flow path, respectively, and for at least one of the depth and width of the recess, the first flow path substrate > the second flow path substrate.

Effects of the Invention

[0011] According to the present disclosure, it is possible to provide a liquid ejection chip in which a decrease in yield is suppressed.

Brief Description of the Drawings

[0012]

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Best Mode for Carrying Out the Invention

[0013] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present disclosure, and not all combinations of features described in the following embodiments are essential for the solution means of the present disclosure. The same reference numerals are assigned to the same components.

[0014] <<First Embodiment>> <Explanation of Yield Reduction> Prior to the description of the present embodiment, an example of yield reduction will be described in more detail. FIG. 1 is a schematic cross-sectional view of a wafer 100 for a liquid ejection head. FIG. 2 is an enlarged view of a portion of a planned cutting line DL. FIG. 3 is a plan view of chips 115 arranged after dicing. In this specification, the one before dicing is referred to as a wafer for a liquid ejection head (or simply a wafer), and the one after dicing is referred to as a liquid ejection chip (or simply a chip).

[0015] As shown in FIG. 1, a first flow path substrate 111 having a groove 103 formed on a planned cutting line DL and a second flow path substrate 112 having a through hole 121 formed on the planned cutting line are formed by bonding via an adhesive 110. In this case, the adhesive 110 extruded by the bonding flows into the groove 103 on the planned cutting line DL. The flowed-in adhesive 110 crawls up and accumulates on the wall surface of the first flow path substrate 111 by the capillary force at the corner of the groove 103 as shown in FIG. 2(a). In the case of the adhesive 110 having no absorption with respect to the laser, the adhesive 110 cannot be modified by the laser and becomes a lump on the chip 115 after dicing. Due to the cohesive force of the adhesive thus formed into a lump, the adhesive adheres to the chip side surface as a lump 113 as shown in FIG. 2(b).

[0016] FIG. 3 is a view of the chip 115 in a plan view. The mass 113 of the adhesive attached to the side surface of the chip protrudes from the outer shape of the chip in the plan view as shown in FIG. 3(b). In the in-line arrangement head in which the chips 115 are continuously arranged in a straight line as shown in FIG. 3(a), let the width of the adhesive protruding from the side surface of the chip be W4, and the chip pitch in the in-line arrangement head be W3. When W4>W3, the adjacent chip 115 and the mass 113 of the adhesive protruding from the side surface of the chip interfere with each other, and the chip 115 cannot be mounted.

[0017] In addition, the mass 113 attached to the side surface of the chip may be detached during the process, and there is a risk that the detached adhesive adheres to the chip, thereby reducing the yield.

[0018] Furthermore, not only in the groove 103, but also on the wall surfaces of the flow path 102 (also referred to as the first flow path) formed in the first flow path substrate 111 or the through hole 123 (also referred to as the second flow path) formed in the second flow path substrate 112, the protruding adhesive 110 crawls along the wall surface. In the flow path 102, there is a concern that the fine flow path to the discharge port 10 may be filled and blocked by the adhesive that has crawled up the wall surface. On the other hand, in the through hole 123, there is a risk that the adhesive 110 that has crawled down the wall surface adheres to the surface opposite to the bonding surface, thereby reducing the yield.

[0019] In the embodiment described below, in the substrate where bonding is performed via the adhesive 110, a configuration for suppressing the crawling of the adhesive flowing into the groove or the through hole onto the wall surface will be described. That is, a liquid discharge chip with a good yield and its manufacturing method will be described.

[0020] <Configuration> Hereinafter, referring to FIG. 1 again, an example of the wafer and the chip for the liquid discharge head in the present embodiment will be described. The wafer 100 for the liquid discharge head is formed by bonding the first flow path substrate 111 and the second flow path substrate 112 with an adhesive 110.

[0021] As shown in Fig. 1, an energy generating element 1 used for discharging liquid is formed on the first flow path substrate 111. Examples of the energy generating element 1 include a heating resistor and a piezoelectric element. Note that wiring for supplying power to the energy generating element 1, pads for electrode connection, etc. are not shown. Fig. 1 is a schematic diagram and details such as the number and arrangement of the energy generating elements 1 are omitted.

[0022] As shown in Fig. 1, an unthrough hole 103 is formed in a part on the planned cutting line DL in the first flow path substrate 111. The unthrough hole 103 is formed from the surface of the first flow path substrate 111 that does not form the layer of the discharge port 10 (in the example of Fig. 1, the surface in the -Z direction).

[0023] In the second flow path substrate 112, various methods can be applied as the formation methods of the through hole 123 for supplying liquid to the energy generating element and the through hole 121 formed on the planned cutting line DL. For example, a method of penetrating from one side of the substrate to the opposite side by dry etching, and a method of forming an unthrough hole from one side and then thinning the substrate by back grinding or CMP to make it through, etc. can be mentioned.

[0024] The formation of these through holes and unthrough holes is performed by a Bosch process which is a kind of reactive ion etching. The Bosch process is a technique for forming etching grooves perpendicular to the substrate by alternately performing coating and etching. A characteristic of this Bosch process is that a shell-shaped shape called a scallop shown in Fig. 4 is formed on the wall surface formed by etching. The scallop is a recess 200 formed continuously on the wall surface, and the inner periphery of the opening is formed continuously in the lamination direction in which the first flow path substrate 111 and the second flow path substrate 112 are laminated.

[0025] Figure 4(a) is an enlarged view showing the α portion in FIG. 1. Figure 4(b) is an enlarged view showing the IVB portion of FIG. 4. In FIG. 4, the scallop depth D is shown. More specifically, two types of scallop depths D1 and D2 are shown. Note that D1 and D2 are indicated by subscripts in the drawing (hereinafter, the same notation shall be used in this specification). The scallop depth is the depth generated by forming the scallop from the wall surface in the state before the scallop is formed. In the example of FIG. 4, it is also the distance in the X direction generated by forming the scallop from the wall surface in the state before the scallop is formed. In this embodiment, the bonding surface of the substrate is defined as the first surface, and the surface that is not the bonding surface is defined as the second surface. At this time, the scallop depth D1 of the wall surface on the first surface side of the second flow path substrate 112 < the scallop depth D2 of the wall surface on the second surface side of the second flow path substrate 112. The scallop depth is defined as the average depth of the scallops of the wall surface etched under the same conditions. The scallop depth is formed shallower if the etching time is short and deeper if the etching time is long.

[0026] Similarly, in FIG. 4, the scallop width W is shown. More specifically, two scallop widths W1 and W2 are shown. The scallop width is the width generated by forming the scallop. In the example of FIG. 4, it is also the distance in the Z direction generated by forming the scallop. In this embodiment, the scallop width W1 of the wall surface on the first surface side of the second flow path substrate 112 < the scallop width W2 of the wall surface on the second surface side of the second flow path substrate 112. The scallop width is defined as the average width of the scallops of the wall surface etched under the same conditions, similar to the scallop depth. The scallop width is formed shorter if the etching time is short and longer if the etching time is long.

[0027] When the wall surface with scallops is joined via the adhesive 110, the protruding adhesive 110 spreads. In the section with the scallop depth D1 (hereinafter referred to as the D1 section), the scallop depth is preferably 0.2 μm or less, more preferably 0.1 μm or less, so that the protruding adhesive 110 can flow easily. Further, in the section with the scallop depth D2 (hereinafter referred to as the D2 section), which is the end point of the spreading, the protruding adhesive 110 is made difficult to flow away, suppressing the exposure of the adhesive on the second surface. To stop the adhesive 110 flowing from the D1 section, the scallop depth is preferably 0.5 μm or more, more preferably 1.0 μm or more. That is, it is preferable that D2 > 2D1. Similarly, it is preferable that W2 > 2W1.

[0028] When comparing a wall surface with a deep scallop depth and a wall surface with a shallow scallop depth, the protruding adhesive 110 preferentially flows and spreads to the side with the shallower scallop depth. The protruding adhesive 110 spreads horizontally in the scallop depressions by capillary force to fill the depressions. When the scallop depth is shallow, less adhesive 110 is required to fill it, and it flows and spreads to the depressions of the next scallop. On the other hand, when the scallop depth is deep, more adhesive 110 is required to fill it compared to the shallow case, and the amount of flowing and spreading relatively decreases.

[0029] As described above, the scallop depth has been used as an example, but the same applies to the scallop width. When comparing a wall surface with a long scallop width and a wall surface with a short scallop width, the protruding adhesive 110 preferentially flows and spreads to the side with the longer scallop width. The protruding adhesive 110 spreads horizontally in the scallop depressions by capillary force to fill the depressions. When the scallop width is short, less adhesive 110 is required to fill it, and it flows and spreads to the depressions of the next scallop. On the other hand, when the scallop width is long, more adhesive 110 is required to fill it compared to the short case, and the amount of flowing and spreading relatively decreases.

[0030] In this embodiment, the D1 section is a section with a scallop width W1, and the D2 section is a section with a scallop width W2. A scallop width of 0.2 μm or less is preferable, and more preferably 0.1 μm or less, so that the protruding adhesive 110 can flow easily. Further, in the D2 section, which is the destination of the flowing adhesive, the protruding adhesive 110 is made difficult to flow, and the exposure of the adhesive on the second surface is suppressed. To stop the adhesive 110 flowing from the D1 section, a scallop width of 0.5 μm or more is preferable, and more preferably 1.0 μm or more.

[0031] In this embodiment, an example where the scallop depth and width are the same within the section has been described. However, the scallop depth and width may be different within the section. Further, in this embodiment, both the scallop depth and width have been described as examples. However, it is sufficient that either one has the relationship described in this embodiment. Hereinafter, for the sake of simplicity of explanation, the scallop depth will mainly be taken as an example for explanation, but the same explanation can also be applied to the scallop width.

[0032] With the configuration as described above, the amount of adhesive flowing along the wall surface of the blind via hole 103 formed in the first base substrate 111 is relatively reduced by passing through the wall surface of the through hole 121 formed in the second base substrate 112, particularly the section with the scallop depth D1. As a result, it is possible to suppress the accumulation of the adhesive 110 at the bottom (plus Z direction) of the blind via hole 103. Further, FIG. 4 has described an example of the wall surfaces of the blind via hole 103 of the first base substrate 111 and the through hole 121 of the second base substrate 112. However, the same configuration can also be applied to the wall surfaces of the through holes of the first base substrate 111 and the second base substrate 112. Note that the lengths of the D1 section and the D2 section may be the same or different. In view of the amount of the protruding adhesive 110, the etching time, etc., the length of each section is appropriately determined.

[0033] Also, in the example of FIG. 4, assume that the scallop depth of the wall surface of the first flow path substrate 111 is of any size but is configured to be deeper than D1. This is to allow the adhesive 110 to flow and spread on the wall surface of the second flow path substrate 112.

[0034] FIGS. 5 and 6 are diagrams showing modified examples. FIGS. 5 and 6 are enlarged views showing the α portion in FIG. 1. In the example of FIG. 4, the wall surface of the second flow path substrate 112 was described, but as shown in FIGS. 5 and 6, the wall surface of the first flow path substrate 111 and the wall surfaces of both the first flow path substrate 111 and the second flow path substrate 112 may also be targeted.

[0035] FIG. 5 shows an example where the scallop depth D1 of the wall surface on the first surface side of the first flow path substrate 111 < the scallop depth D2 of the wall surface on the second surface side of the first flow path substrate 111. In the case of the example of FIG. 5, the protruding adhesive 110 will flow along the D1 section in the first flow path substrate 111. However, in the D2 section, which is the further downstream section, it is possible to make it difficult for the protruding adhesive 110 to flow further and suppress the exposure of the adhesive 110 on the second surface (or the bottom of the unperforated hole 103).

[0036] FIG. 6 is an example combining the second flow path substrate 112 described in FIG. 4 and the first flow path substrate 111 described in FIG. 5. That is, FIG. 6 shows an example where the scallop depth D1 of the wall surface on the first surface side of the first flow path substrate 111 and the second flow path substrate 112 < the scallop depth D2 of the wall surface on the second surface side of the first flow path substrate 111 and the second flow path substrate 112. Also in the example of FIG. 6, the protruding adhesive 110 will flow along the D1 section in the first flow path substrate 111 and the second flow path substrate 112. However, in the D2 section, which is the further downstream section, it is possible to make it difficult for the protruding adhesive 110 to flow further and suppress the exposure of the adhesive 110 on the second surface (or the bottom of the unperforated hole 103).

[0037] An example of the adhesive 110 will be described. As the adhesive 110, a material with high adhesion to the substrate is preferably used. Further, as the adhesive 110, a material with less contamination such as air bubbles and high coatability is preferred, and a low-viscosity material that is easy to reduce the thickness of the adhesive 110 is preferred. The adhesive 110 preferably contains any resin selected from the group consisting of epoxy resin, acrylic resin, silicone resin, benzocyclobutene resin, polyamide resin, polyimide resin, and urethane resin. Examples of the curing method of the adhesive 110 include a thermal curing method and an ultraviolet delayed curing method. In addition, when any of the substrates has ultraviolet transmittance, an ultraviolet curing method can also be used.

[0038] As a method of applying the adhesive 110, an adhesive transfer method using a substrate can be mentioned. Specifically, a transfer substrate is prepared, and the adhesive is thinly and uniformly applied onto the transfer substrate by a spin coating method or a slit coating method. Then, by bringing the adhesive surface of the first base substrate 111 into contact with the applied adhesive, the adhesive 110 can be transferred only to the adhesive surface of the first base substrate 111. The size of the transfer substrate is preferably the same size or larger than that of the first base substrate 111. As the substrate, silicon or glass, PET or PEN, or a film such as PI is preferably used. Further, as a method of directly forming the adhesive on the first base substrate 111, screen printing or dispense coating can be mentioned. Here, an example of applying the adhesive 110 to the first base substrate 111 has been described, but the adhesive 110 may be applied to the second base substrate 112.

[0039] The first base substrate 111 coated with the adhesive 110 and the second base substrate 112 are joined by heating the substrates to a predetermined temperature in a joining apparatus and then applying pressure at a predetermined time and pressure. Joining parameters such as time and pressure are appropriately set according to the adhesive material. It is preferable to join in a vacuum to suppress the mixing of air bubbles into the joint.

[0040] When the adhesive 110 is a thermosetting type, it may be heated until it cures within the bonding apparatus. Alternatively, after taking out the substrate assembly after bonding, it may be heated separately in an oven or the like to promote curing. When the adhesive 110 is an ultraviolet-delay type, the adhesive 110 is irradiated with a specified amount of ultraviolet rays in advance before bonding, and then bonding is performed. After bonding, it is preferable to further heat the substrate assembly to sufficiently promote curing. When the adhesive 110 is an ultraviolet-curing type, after bonding the substrates, the adhesive 110 is irradiated with a specified amount of ultraviolet rays through the ultraviolet-transmissive substrate to cure it. After bonding, it is preferable to further heat the substrate assembly to sufficiently promote curing.

[0041] For the flow path substrate for which bonding has been completed, as shown in FIG. 1, the flow path layer 3 and the nozzle layer 2 are formed, and the wafer 100 for the liquid ejection head is completed. Then, the liquid ejection chip 115 can be obtained by chip singulation of the wafer 100 for the liquid ejection head by stealth dicing using a laser.

[0042] As described above, according to the present embodiment, it is possible to provide a liquid ejection chip in which a decrease in yield is suppressed. That is, in the present embodiment, by controlling the amount of upward and downward creep of the adhesive 110 on the flow path wall surface, it is possible to manufacture a liquid ejection chip with a good yield.

[0043] <<Second Embodiment>> In the first embodiment, an example in which the scallop depth is provided in two steps (D1 and D2) has been described. In the present embodiment, an example in which the scallop depth is provided in n steps (n is 3 or more) will be described. When n is 2, two or more types of scallop depths are provided, and the first embodiment is included. In the present embodiment, n is assumed to be 3 or more. As described in the first embodiment, the scallop depth is taken as an example for explanation, but the same applies to the scallop width.

[0044] FIG. 7 is an enlarged view showing the α portion of FIG. 1 in the present embodiment. FIG. 7 shows an example in which the scallop depth is provided in n steps on the second flow path substrate 112. As described in the modification of the first embodiment, the scallop depth may be provided in n steps on the first flow path substrate 111. The scallop depth may be provided in n steps on each of both the first flow path substrate 111 and the second flow path substrate 112.

[0045] In FIG. 7, in the second flow path substrate 112, when the scallop depth of the wall surface on the first surface side is D1, and the scallop depths are D2, D3, ··· Dn-1, Dn toward the second surface, an example where D1 < D2 < D3 < ··· < Dn-1 < Dn is shown. If the scallop depth is changed abruptly, the balance of the etching conditions may be disrupted and shape abnormalities may occur at the change interface. By changing the scallop depth stepwise in multiple steps as in the present embodiment, a rapid change in the etching conditions can be avoided, and the wall surface can be formed without shape abnormalities. For example, when the etching step times of the scallop depths D1, D2, D3 ··· Dn are E1, E2, E3, ··· En, the above scallop depths can be formed by setting En > ··· > E3 > E2 > E1.

[0046] The length of each section can be an arbitrary length, but in order to suppress the creeping up of the protruding adhesive 110, the roles of the sections at both ends (D1 and Dn) are important. Since the intermediate sections (D2, D3, ··· Dn-1) are the connecting sections required during processing, the length of the intermediate sections may be shorter than the lengths of the sections at both ends.

[0047] In the case of the first flow path substrate 111 as well, when the scallop depth of the wall surface on the first surface side is D1, and the scallop depths are D2, D3, ···, Dn-1, Dn toward the second surface, it may be set as D1 < D2 < D3 < ··· < Dn-1 < Dn. It is preferable that Dn > 2D1 in both the case of the first flow path substrate 111 and the case of the second flow path substrate 112.

[0048] The scallop width is the same. When the scallop depth of the wall surface on the first surface side is W1 and the scallop widths are W2, W3, ···, Wn-1, Wn toward the second surface, it may be set as W1 < W2 < W3 < ··· < Wn-1 < Wn. Also, it is preferable that Wn > 2W1.

[0049] In addition, as described above, in order to avoid a sudden change in the etching conditions, when the scallop depth of the wall surface on the first surface side is D1 and the scallop depths are D2, D3, ···, Dn-1, Dn toward the second surface, it is preferably set as D1 < D2 < D3 < ··· < Dn-1 < Dn, but this is not the only case. The scallop depth may be reversed in some sections in the intermediate zone.

[0050] <<Embodiment 3>> In this embodiment, an example in which the scallop depths of the wall surfaces of the first flow path substrate 111 and the second flow path substrate 112 are relatively different will be described. More specifically, an example in which Da > Db will be described, where Da is the scallop depth of the wall surface of the non-through hole 103 of the first flow path substrate 111 and Db is the scallop depth of the wall surface of the through hole 121 of the second flow path substrate 112. As described in the first embodiment, the scallop depth is taken as an example for explanation, but the same applies to the scallop width.

[0051] FIG. 8 is an enlarged view showing the α portion of FIG. 1 in the present embodiment. As shown in FIG. 8, the scallop depth Da of the wall surface of the non-through hole 103 of the first flow path substrate 111 is configured to be deeper than the scallop depth Db of the wall surface of the through hole 121 of the second flow path substrate 112. When comparing the wall surface with a deep scallop depth and the wall surface with a shallow scallop depth, the protruding adhesive 110 preferentially flows and spreads toward the wall surface with the shallow scallop depth. The protruding adhesive 110 is laterally transmitted through the capillary force in the scallop depression and fills the depression. When the scallop depth is shallow, less adhesive is required to fill it, and it flows and spreads to the depression of the next scallop. On the other hand, when the scallop depth is deep, more adhesive is required to fill it compared to the case of a shallow scallop depth, and the amount of flow and spread relatively decreases. From the above, by setting Da>Db, more of the protruding adhesive 110 flows and spreads to the wall surface of the through hole 121 than to the wall surface of the non-through hole 103, and the accumulation of adhesive at the bottom of the non-through hole 103 can be suppressed. As an example, Da can be 1.5 times or more and 10 times or less of Db. As described above, the scallop width can be the same.

[0052] In addition, the present embodiment may be combined with the examples described in the first embodiment or the second embodiment. That is, it is only necessary to maintain the relationship that the scallop depth Da of the wall surface of the first flow path substrate 111> the scallop depth Db of the second flow path substrate 112, and multiple stages of depths may be formed on each substrate. Further, as described in the second embodiment, when configuring a multi-stage scallop depth, the stages may be changed between the first flow path substrate 111 and the second flow path substrate 112.

[0053] Also, in relation to the second embodiment, n - stage scallop depths may be provided when viewed from the entirety of both the first flow - path substrate 111 and the second flow - path substrate 112. Even in this case, it is sufficient that the relationship of the scallop depth Da of the wall surface of the first flow - path substrate 111> the scallop depth Db of the second flow - path substrate 112 is maintained. For example, the scallop depth at the boundary portion between the first flow - path substrate 111 and the second flow - path substrate 112 may be reversed. As will be described later, the first flow - path substrate 111 and the second flow - path substrate 112 are etched separately. Therefore, when n - stage scallop depths are provided when viewed from the entirety of both the first flow - path substrate 111 and the second flow - path substrate 112, the scallop depth at the boundary portion between the first flow - path substrate 111 and the second flow - path substrate 112 may be reversed. When multiple - stage scallop depths are formed, it is sufficient that, when viewed as a whole, the average is such that the scallop depth Da of the wall surface of the first flow - path substrate 111> the scallop depth Db of the second flow - path substrate 112.

[0054] <<Example>> Hereinafter, examples of each of the embodiments described in the first to third embodiments will be described. Example 1 corresponds to the first embodiment, Example 2 corresponds to the second embodiment, and Example 3 corresponds to the third embodiment. In the examples, a method for manufacturing a wafer for liquid ejection (liquid ejection chip) will be described.

[0055] <Example 1> Example 1 will be described with reference to FIGS. 9 to 16. FIG. 9 is a diagram showing the manufacturing process of the first flow - path substrate 111. FIGS. 10, 11, and 12 are diagrams showing the manufacturing process of the second flow - path substrate 112. FIGS. 13 and 14 are diagrams showing the bonding process. FIG. 15 is a diagram showing the manufactured wafer 100 for a liquid ejection head. FIG. 16 is a diagram showing a summary of Example 1.

[0056] First, as shown in Fig. 9(a), a first flow path substrate 111 is prepared. On the first flow path substrate 111, an energy generating element 1 made of TaSiN used for discharging droplets, an electric circuit (not shown) for driving the energy generating element 1, and an electrical connection portion (not shown) electrically connected to the electrical connection substrate are formed. Such a first flow path substrate 111 is prepared. The substrate is made of silicon and is thinly processed by a grinding device until the substrate thickness becomes 625 μm.

[0057] On the first flow path substrate 111 prepared in this way, a flow path 102 and an unperforated hole 103 on the cutting planned line are formed. Specifically, as shown in Fig. 9(b), on the bonding surface side, an etching mask resist 130 corresponding to the flow path 102 and the unperforated hole 103 on the cutting planned line is formed using photolithography technology.

[0058] Next, as shown in Fig. 9(c), using the Bosch process, the flow path 102 and the unperforated hole 103 are simultaneously processed from the bonding surface of the first flow path substrate 111 so that the processing depth becomes 450 μm. The etching rate for silicon at this time is 7 μm / min, and the processing time is 65 minutes. Then, the etching mask resist is peeled off.

[0059] Next, an etching mask resist with an opening provided at a location that becomes a through-flow path is formed from the surface on which the energy generating element 1 is formed using photolithography technology. Then, etching is performed using the Bosch process so that the unperforated hole with a depth of 450 μm formed in the first flow path substrate 111 penetrates, and the etching mask resist is peeled off. In this way, as shown in Fig. 9(d), a flow path 102 and an unperforated unperforated hole 103 are formed in the first flow path substrate 111.

[0060] Next, the process of the second sub-base plate 112 will be described. As the second sub-base plate 112, a 725-μm silicon substrate was prepared, and an etching mask resist 130 was formed on the surface to be etched using photolithography technology. Next, as shown in FIGS. 10(a) and (b), a section with a scallop depth D2 was formed using the Bosch process. The etching conditions at this time were as follows: C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2500 W, and a coating time of 3.9 seconds. Next, SF6 gas was used for etching the coating layer, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2500 W, and an etching time of 3.5 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 700 sccm, a chamber pressure of 12.0 Pa, a coil power of 2000 W, and an etching time of 10 seconds. Processing was carried out to a depth of 150 μm under these conditions. The scallop depth D2 under these conditions was 1.2 μm.

[0061] Next, as shown in FIGS. 11(a) and (b), a section with a scallop depth D1 was continuously formed using the Bosch process following the D2 section. The etching conditions at this time were as follows: C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 6.0 Pa, a coil power of 2200 W, and a coating time of 1.3 seconds. Next, SF6 gas was used for etching the coating layer, with a gas flow rate of 400 sccm, a chamber pressure of 3.5 Pa, a coil power of 2200 W, and an etching time of 3.0 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2200 W, and an etching time of 1.5 seconds. Processing was carried out to a depth of 330 μm in combination with the D2 section under these conditions. The scallop depth D1 under these conditions was 0.15 μm.

[0062] Next, as shown in FIGS. 12(a) and (b), the substrate was ground from the unetched surface to a thickness of 300 μm to form the through-hole 121 and the through-hole 123.

[0063] Next, a base material for adhesive transfer (not shown) was prepared, and a benzocyclobutene solution as an adhesive was spin-coated onto the base material for adhesive transfer to a thickness of 7 μm. A PET film was used as the transfer base material. Further, in order to volatilize the solvent after coating, a baking treatment was performed at 100°C for 5 minutes. By bringing the adhesive formed on the transfer base material into contact with the bonding surface of the first flow path substrate 111 while applying heat, as shown in FIG. 13, the adhesive 110 was transferred onto the first flow path substrate 111.

[0064] Next, using a bonding alignment apparatus (not shown), the first flow path substrate 111 and the second flow path substrate 112 were aligned and heated in a vacuum to perform bonding. The bonding was performed at a vacuum degree of 100 Pa or less and a temperature of 150°C. After completion of the bonding and cooling, the first flow path substrate 111 and the second flow path substrate 112 were taken out from the bonding alignment apparatus, and heat treatment was performed at 250°C for 1 hour in an oven in a nitrogen atmosphere to cure the adhesive. As shown in FIGS. 14(a) and (b), a part of the adhesive 110 softened during bonding or curing protrudes from the wall surface during bonding. Then, the amount of the adhesive 110 that protruded during bonding flowed along the D1 section of the opening wall surface of the second flow path substrate 112 and was able to suppress the amount that flowed along to the wall surface of the non-through hole 103 of the first flow path substrate 111.

[0065] Next, a solution in which a negative photosensitive resin was dissolved in a PGMEA solvent was spin-coated onto a PET film and dried at 100°C in an oven to form a dry film. This dry film was transferred onto the energy generating element forming surface of the first flow path substrate 111, and the PET film was peeled off to form a photosensitive resin layer 3 as shown in FIG. 15. A pattern serving as a flow path was exposed on the photosensitive resin layer 3, and then PEB (Post Exposure Bake) was performed to obtain a latent image state. Subsequently, a dry film was similarly laminated, and a pattern serving as a nozzle was exposed. Thereafter, PEB was performed and the flow path and the nozzle were developed together to form a nozzle layer 2 as shown in FIG. 15, and the wafer 100 for a liquid ejection head was completed.

[0066] Next, a plurality of altered layers were formed in the thickness direction of the silicon substrate inside the wafer 100 for the liquid ejection head by stealth dicing using a laser. Then, by applying stress to the wafer, cracks propagated in the altered portions, enabling the wafer to be cleaved to obtain the liquid ejection chip 115 (FIG. 3).

[0067] In this liquid ejection chip 115, as described above, the adhesive softened during bonding or curing was in a state where it was flowing along the D1 section of the opening wall surface of the second flow path substrate 112, and the adhesive 110 that protruded during bonding was flowing. That is, since the amount flowing to the wall surface of the unpenetrated unpenetrated hole 103 of the first flow path substrate 111 could be suppressed, the adhesive 110 did not accumulate at the opening on the planned cutting line of the first flow path substrate 111, and the generation of the cured adhesive that protruded from the chip side surface could be suppressed.

[0068] Also, when forming an in-line type liquid ejection head in which a plurality of the thus manufactured liquid ejection chips are arranged, an in-line type liquid ejection head with good yield and no interference with adjacent chips could be obtained.

[0069] FIG. 16 is a diagram summarizing the etching conditions in the Bosch process of Example 1.

[0070] <Example 2> In Example 2, the differences from Example 1 will be described. Example 2 will be described with reference to FIGS. 17 to 22. FIGS. 17, 18, 19, 20, and 21 are diagrams showing the manufacturing process of the second flow path substrate 112. FIG. 22 is a diagram showing a summary of Example 2. Example 2 differs from Example 1 in the processing conditions of the second flow path substrate 112.

[0071] As the second-class base plate 112, a 725-μm silicon substrate was prepared, and an etching mask resist 130 was formed on the surface to be etched using photolithography technology. Next, as shown in FIGS. 17(a) and (b), a section with a scallop depth D4 was formed using the Bosch process. As the etching conditions at this time, C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2500 W, and a coating time of 3.9 seconds. Next, SF6 gas was used for coating layer etching, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2500 W, and an etching time of 3.5 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 700 sccm, a chamber pressure of 12.0 Pa, a coil power of 2000 W, and an etching time of 10 seconds. Processing was carried out to a depth of 100 μm under these conditions. The scallop depth D4 under these conditions was 1.2 μm.

[0072] Next, as shown in FIGS. 18(a) and (b), a section with a scallop depth D3 was continuously formed using the Bosch process following the D4 section. As the etching conditions at this time, C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 4.6 Pa, a coil power of 2400 W, and a coating time of 3.0 seconds. Next, SF6 gas was used for coating layer etching, with a gas flow rate of 400 sccm, a chamber pressure of 3.8 Pa, a coil power of 2400 W, and an etching time of 3.3 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 600 sccm, a chamber pressure of 9.5 Pa, a coil power of 2070 W, and an etching time of 7.2 seconds. Processing was carried out to a depth of 150 μm in combination with the D4 section under these conditions. The scallop depth D3 under these conditions was 0.8 μm.

[0073] Next, as shown in FIGS. 19(a) and (b), the section with the scallop depth D2 was continuously formed following the D3 section using the Bosch process. As the etching conditions at this time, C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 5.2 Pa, a coil power of 2300 W, and a coating time of 2.1 seconds. Next, SF6 gas was used for etching the coating layer, with a gas flow rate of 400 sccm, a chamber pressure of 3.8 Pa, a coil power of 2400 W, and an etching time of 3.3 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 500 sccm, a chamber pressure of 9.5 Pa, a coil power of 2140 W, and an etching time of 4.4 seconds. Processing was performed up to a depth of 200 μm in combination with the D4·D3 sections under these conditions. The scallop depth D2 under these conditions was 0.4 μm.

[0074] Next, as shown in FIGS. 20(a) and (b), the section with the scallop depth D1 was continuously formed following the D2 section using the Bosch process. As the etching conditions at this time, C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 6.0 Pa, a coil power of 2200 W, and a coating time of 1.3 seconds. Next, SF6 gas was used for etching the coating layer, with a gas flow rate of 400 sccm, a chamber pressure of 3.5 Pa, a coil power of 2200 W, and an etching time of 3.0 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2200 W, and an etching time of 1.5 seconds. Processing was performed up to a depth of 320 μm in combination with the D4·D3·D2 sections under these conditions. The scallop depth D1 under these conditions was 0.15 μm.

[0075] Next, as shown in FIGS. 21(a) and (b), the substrate was ground from the unetched surface to a thickness of 300 μm to form the through holes 121 and 123.

[0076] According to this embodiment, a liquid ejection chip with a good yield and no roughness on the etched side surface, which may become a foreign object when detached, could be obtained.

[0077] FIG. 22 is a diagram summarizing the etching conditions in the Bosch process of Example 2.

[0078] <Example 3> Example 3 will describe the differences from Example 1. Example 3 will be described with reference to FIGS. 23 to 26. FIG. 23 is a diagram showing the manufacturing process of the first flow path substrate 111. FIGS. 24 and 25 are diagrams showing the manufacturing process of the second flow path substrate 112. FIG. 26 is a diagram showing a summary of Example 3. Example 3 is an example that defines the relationship between the etching conditions for forming the flow path 102 and the unperforated holes 103 on the cutting planned line in the first flow path substrate 111 in Example 1 and the etching conditions for forming the through grooves in the second flow path substrate 112.

[0079] As shown in FIGS. 23(a) and (b), an etching mask resist 130 corresponding to the flow path 102 and the unperforated holes 103 on the cutting planned line was formed on the bonding surface side of the first flow path substrate 111 using photolithography technology. Further, a section with a scallop depth Da was formed from the surface that becomes the bonding surface using the Bosch process. As the etching conditions at this time, C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2500 W, and a coating time of 3.9 seconds. Next, SF6 gas was used for coating layer etching, with a gas flow rate of 400 sccm, a chamber pressure of 4.0 Pa, a coil power of 2500 W, and an etching time of 3.5 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 700 sccm, a chamber pressure of 12.0 Pa, a coil power of 2000 W, and an etching time of 10 seconds. Processing was performed up to a depth of 450 μm under these conditions. The scallop depth Da under these conditions was 1.2 μm. After that, a first flow path substrate that was penetrated through the same process as in Example 1 was formed.

[0080] Next, as the second flow path substrate 112, a 725-μm silicon substrate was prepared, and an etching mask resist 130 was formed on the surface to be etched using photolithography technology. Next, as shown in FIGS. 24(a) and (b), a section having a scallop depth Db was continuously formed following the Da section using the Bosch process. As the etching conditions at this time, C4F8 gas was used in the coating step, with a gas flow rate of 400 sccm, a chamber pressure of 5.2 Pa, a coil power of 2300 W, and a coating time of 2.1 seconds. Next, SF6 gas was used for coating layer etching, with a gas flow rate of 400 sccm, a chamber pressure of 3.8 Pa, a coil power of 2400 W, and an etching time of 3.3 seconds. Next, SF6 gas was used for silicon etching, with a gas flow rate of 500 sccm, a chamber pressure of 9.5 Pa, a coil power of 2140 W, and an etching time of 4.4 seconds. Processing was performed up to a depth of 320 μm under these conditions. The scallop depth Db under these conditions was 0.4 μm. Thereafter, a second flow path substrate 112 that had been penetrated through the same steps as in Example 1 was formed.

[0081] According to this embodiment, when the first flow path substrate 111 and the second flow path substrate 112 were joined using the adhesive 110, the adhesive 110 protruding from the joining interface was more likely to creep along the wall surface of the second flow path substrate 112 than the wall surface of the first flow path substrate 111. Therefore, it was possible to suppress the amount of the adhesive that flowed along the wall surface of the unpenetrated hole 103, and a liquid discharge chip 115 was obtained in which the adhesive did not accumulate at the opening on the planned cutting line of the first flow path substrate 111 and the generation of a cured adhesive protruding from the side surface of the chip was suppressed.

[0082] FIG. 26 is a diagram summarizing the etching conditions in the Bosch process of Example 3.

[0083] <<Other Embodiments>> In the above-described embodiments, an example in which the unopened groove on the planned cutting line is formed in the first flow path substrate 111 has been described, but this is not the only case. The unopened groove on the planned cutting line may be formed in the second flow path substrate 112. Even in this case, by applying the configurations of the above-described embodiments, it is possible to suppress the remaining of the lumps of the adhesive protruding in the unopened groove on the planned cutting line in the second flow path substrate 112. Thus, it is sufficient that an unopened groove is formed on the planned cutting line of one of the first flow path substrate 111 and the second flow path substrate 112, and a through hole is formed on the planned cutting line of the other substrate.

[0084] The disclosure of the present embodiment includes configurations typified by the following examples of a recording apparatus and a control method of a recording apparatus.

[0085] <Configuration 1> A first flow path substrate having an energy generating element that generates energy for discharging a liquid and a first flow path that supplies the liquid to the energy generating element, A liquid discharge chip in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, Recesses are respectively formed on the wall surface of the first flow path and the wall surface of the second flow path, A liquid discharge chip in which at least one of the depth and width of the recess is greater in the first flow path substrate than in the second flow path substrate.

[0086] <Configuration 2> In the liquid discharge chip according to Configuration 1, at least one of the depth and width of the recess in the first flow path substrate is 1.5 times or more and 10 times or less of at least one of the depth and width of the recess in the second flow path substrate.

[0087] <Configuration 3> Recesses having at least one of two or more types of depths and widths are formed on the wall surface of the second flow path of the second flow path substrate, When the joint surface of the second flow path substrate with the first flow path substrate is defined as a first surface and the surface opposite to the first surface is defined as a second surface, In the second flow path, at least one of the depth and width of the recess on the first surface side < at least one of the depth and width of the recess on the second surface side, The liquid ejection chip according to Configuration 1 or 2, which is such.

[0088] <Configuration 4> A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element, A liquid ejection chip in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, Recesses having at least one of two or more types of depths and widths are formed on at least one of the wall surfaces of the first flow path and the second flow path, When the bonding surfaces of the first flow path substrate and the second flow path substrate are each a first surface and the surface opposite to the first surface is a second surface, at least one of the depth and width of the recess on the first surface side < at least one of the depth and width of the recess on the second surface side, The liquid ejection chip which is such.

[0089] <Configuration 5> When the depth of the recess on the first surface side in at least one of the first flow path substrate and the second flow path substrate is D1 and the width of the recess is W1, When the depth of the recess from the first surface side to the second surface side is D1, D2, ···, Dn and the width is W1, W2, ···, Wn, and n is 3 or more, The liquid ejection chip according to Configuration 4, wherein D1 < D2 < ··· < Dn or W1 < W2 < ··· < Wn.

[0090] <Configuration 6> When the depth of the recess on the first surface side is D1 and the width is W1, and the depth of the recess on the second surface side is Dn and the width is Wn, Dn > 2D1 or Wn > 2W1. The liquid ejection chip according to Configuration 4 or 5.

[0091] <Configuration 7> The liquid ejection chip according to any one of Configurations 1 to 6, wherein the concave portion is formed continuously in the stacking direction in which the inner periphery of the opening is stacked with the first flow path substrate and the second flow path substrate.

[0092] <Configuration 8> The liquid ejection chip according to any one of Configurations 1 to 7, wherein the depth of the concave portion is the average depth of the wall surface etched under the same conditions, and the width of the concave portion is the average width of the wall surface etched under the same conditions.

[0093] <Configuration 9> A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element, A wafer for a liquid ejection head in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, An unopened groove is formed on a planned cutting line of one of the first flow path substrate and the second flow path substrate, and a through hole is formed on a planned cutting line of the other substrate, Concave portions are formed on the wall surface of the first flow path, the wall surface of the second flow path, the groove, and the through hole, respectively, A wafer for a liquid ejection head, wherein at least one of the depth and width of the concave portion is such that the first flow path substrate > the second flow path substrate.

[0094] <Configuration 10> A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element, A wafer for a liquid ejection head in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, An unopened groove is formed on a planned cutting line of one of the first flow path substrate and the second flow path substrate, and a through hole is formed on a planned cutting line of the other substrate, Concave portions having at least one of two or more types of depths and widths are formed on at least one of the wall surfaces of the first flow path and the second flow path, and the groove and the through hole. When the joint surfaces of the first flow path substrate and the second flow path substrate are respectively defined as the first surfaces, and the surfaces opposite to the first surfaces are defined as the second surfaces, at least one of the depth and width of the recess on the first surface side < at least one of the depth and width of the recess on the second surface side, A wafer for liquid ejection, which is as described above.

[0095] <Configuration 11> A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element, A method for manufacturing a liquid ejection chip in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, The method includes a step of forming recesses on the wall surface of the first flow path and the wall surface of the second flow path respectively, A method for manufacturing a liquid ejection chip, wherein for at least one of the depth and width of the recess, the first flow path substrate > the second flow path substrate.

[0096] <Configuration 12> A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element, A method for manufacturing a liquid ejection chip in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, The method includes a step of forming a recess having at least one of two or more types of depths and widths on the wall surface of at least one of the first flow path and the second flow path, When the joint surfaces of the first flow path substrate and the second flow path substrate are respectively defined as the first surfaces, and the surfaces opposite to the first surfaces are defined as the second surfaces, at least one of the depth and width of the recess on the first surface side < at least one of the depth and width of the recess on the second surface side, A method for manufacturing a liquid ejection chip, which is as described above.

[0097] <Configuration 13> The method for manufacturing a liquid ejection chip according to Configuration 11 or 12, wherein the recess is formed using a Bosch process.

[0098] <Structure 14> As the conditions of the Bosch process, when the etching step times of the depths D1, D2, D3 ··· Dn of the recesses are E1, E2, E3, ··· En, En > ··· > E3 > E2 > E1, the method for manufacturing a liquid ejection chip according to Structure 13.

[0099] <Structure 15> An unopened groove is formed on one of the cutting planned lines of the first flow path substrate and the second flow path substrate, and a through hole is formed on the cutting planned line of the other substrate. By irradiating laser light along the cutting planned line, a modified portion is formed inside the first flow path substrate or inside the first flow path substrate and the second flow path substrate, and by applying stress to the modified portion, the substrate is cut and divided to further have a step of manufacturing a plurality of the liquid ejection chips, the method for manufacturing a liquid ejection chip according to any one of Structures 11 to 14.

Explanation of Signs

[0100] 1: Energy generating element 2: Nozzle layer 3: Flow path layer 102: Flow path 103: Unperforated hole 110: Adhesive 111: First flow path substrate 112: Second flow path substrate

Claims

1. A first flow path substrate having an energy generating element that generates energy for discharging a liquid and a first flow path that supplies the liquid to the energy generating element, A liquid discharge chip in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, Recesses are formed on the wall surface of the first flow path and the wall surface of the second flow path, respectively, A liquid discharge chip in which at least one of the depth and width of the recess is such that the first flow path substrate > the second flow path substrate.

2. At least one of the depth and width of the recess in the first flow path substrate is 1.5 times or more and 10 times or less of at least one of the depth and width of the recess in the second flow path substrate. The liquid discharge chip according to claim 1.

3. Recesses having at least one of two or more types of depth and width are formed on the wall surface of the second flow path of the second flow path substrate. When the joint surface of the second flow path substrate with the first flow path substrate is defined as the first surface and the surface opposite to the first surface is defined as the second surface, In the second flow path, at least one of the depth and width of the recess on the first surface side < at least one of the depth and width of the recess on the second surface side, The liquid discharge chip according to claim 1.

4. A first flow path substrate having an energy generating element that generates energy for discharging a liquid and a first flow path that supplies the liquid to the energy generating element, A liquid discharge chip in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, Recesses having at least one of two or more types of depth and width are formed on the wall surface of at least one of the first flow path and the second flow path, When the joint surfaces in the first flow path substrate and the second flow path substrate are each defined as a first surface, and the surface opposite to the first surface is defined as a second surface, at least one of the depth and width of the recess on the first surface side < at least one of the depth and width of the recess on the second surface side, which is a liquid ejection chip.

5. When the depth of the recess on the first surface side in at least one of the first flow path substrate and the second flow path substrate is D1 and the width of the recess is W1, When the depth of the recess from the first surface side to the second surface side is D1, D2,..., Dn and the width is W1, W2,..., Wn, and n is 3 or more, The liquid ejection chip according to claim 4, wherein D1 < D2 <... < Dn or W1 < W2 <... < Wn.

6. The liquid ejection chip according to claim 4, wherein when the depth of the recess on the first surface side is D1 and the width is W1, and the depth of the recess on the second surface side is Dn and the width is Wn, Dn > 2D1 or Wn > 2W1.

7. The liquid ejection chip according to any one of claims 1 to 6, wherein the recess is formed continuously in the stacking direction in which the inner periphery of the opening is stacked with the first flow path substrate and the second flow path substrate.

8. The liquid ejection chip according to any one of claims 1 to 6, wherein the depth of the recess is the average depth of the wall surface etched under the same conditions, and the width of the recess is the average width of the wall surface etched under the same conditions.

9. A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element, A wafer for a liquid ejection head in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, An unopened groove is formed on the cutting planned line of one of the first flow path substrate and the second flow path substrate, and a through hole is formed on the cutting planned line of the other substrate, Recesses are respectively formed on the wall surfaces of the first flow path, the wall surfaces of the second flow path, the grooves, and the through holes. A wafer for a liquid ejection head, wherein at least one of the depth and width of the recess satisfies the relationship: the first flow path substrate > the second flow path substrate.

10. A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element; A wafer for a liquid ejection head, in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, An unopened groove is formed on a cutting planned line of one of the first flow path substrate and the second flow path substrate, and a through hole is formed on a cutting planned line of the other substrate, Recesses having at least one of two or more types of depths and widths are formed on at least one of the wall surfaces of the first flow path and the second flow path, and on the grooves and the through holes, When the bonding surfaces of the first flow path substrate and the second flow path substrate are respectively defined as the first surfaces, and the surfaces opposite to the first surfaces are defined as the second surfaces, at least one of the depth and width of the recesses on the first surface side < at least one of the depth and width of the recesses on the second surface side, A wafer for liquid ejection.

11. A first flow path substrate having an energy generating element that generates energy for ejecting a liquid and a first flow path that supplies the liquid to the energy generating element; A method for manufacturing a liquid ejection chip, in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, The method includes a step of forming recesses on the wall surfaces of the first flow path and the second flow path respectively, A method for manufacturing a liquid ejection chip, wherein at least one of the depth and width of the recess satisfies the relationship: the first flow path substrate > the second flow path substrate.

12. A first flow path substrate having an energy generating element that generates energy for discharging a liquid and a first flow path that supplies the liquid to the energy generating element, A method for manufacturing a liquid discharge chip in which a second flow path substrate having a second flow path connected to the first flow path is joined via an adhesive, The method includes a step of forming recesses having at least one of two or more depths and widths on at least one wall surface of the first flow path and the second flow path, When the joint surfaces of the first flow path substrate and the second flow path substrate are respectively defined as the first surface and the surface opposite to the first surface is defined as the second surface, at least one of the depth and width of the recess on the first surface side < at least one of the depth and width of the recess on the second surface side, A method for manufacturing a liquid discharge chip.

13. The method for manufacturing a liquid discharge chip according to claim 11 or 12, wherein the recess is formed using a Bosch process.

14. As conditions of the Bosch process, when the etching step times of the depths D1, D2, D3... Dn of the recesses are E1, E2, E3,... En, En >... > E3 > E2 > E1. The method for manufacturing a liquid discharge chip according to claim 13.

15. An unopened groove is formed on the cutting planned line of one of the first flow path substrate and the second flow path substrate, and a through hole is formed on the cutting planned line of the other substrate, By irradiating laser light along the cutting planned line, a modified portion is formed inside the first flow path substrate or inside the first flow path substrate and the second flow path substrate, and by applying stress to the modified portion, the substrate is cut and divided to manufacture a plurality of the liquid discharge chips. The method for manufacturing a liquid discharge chip according to claim 11.

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