Liquid ejection head manufacturing method and liquid ejection head

Abstract

To provide a manufacturing method for a liquid ejection head having high adhesion between a protective layer and a laminating member on the protective layer even when a modified layer is formed on the protective layer for a heating element, a circuit and the like on a substrate.SOLUTION: A manufacturing method for a liquid ejection head having a substrate, a protective layer covering at least a part of the substrate, and a laminating member formed on the protective layer has a step of forming the protective layer on at least the part of the substrate, and a step of forming the laminating member on the protective layer such that a part of the protective layer is exposed therefrom. The protective layer contains at least Si and C. The content of oxygen in a bulk of the protective layer is less than 20 atomic% in terms of an elemental composition ratio. A modified layer having an oxygen content of 20 atomic% or more in terms of an elemental composition ratio is present in a surface of the protective layer, and the thickness of the modified layer is 3.40 nm or less between the protective layer and the laminating member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a liquid ejection head and a liquid ejection head. [Background technology]

[0002] In a liquid ejection head such as an inkjet head, a liquid supply port and a liquid flow path for discharging the ejected liquid are formed on a substrate made of silicon or the like. One method of ejecting liquid is to use a heating element to heat the liquid to cause bubbles, and then eject the liquid by utilizing the growth of these bubbles. In this type of liquid ejection head, the heating element and a circuit for driving the heating element are formed on the substrate.

[0003] It is known that SiN films formed by CVD have been used as insulating protective layers to protect the substrate, heating elements, and circuits of liquid ejection heads from the ejected liquid (Patent Document 1). However, with the recent diversification of ejection liquids, some ejection liquids have emerged that dissolve materials used in conventional liquid ejection heads, such as SiN. SiCN films formed by CVD are sometimes used as protective layers to protect the substrate, heating elements, and circuits from such ejection liquids (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-225708 [Patent Document 2] Japanese Patent Application Publication No. 2017-121813 Summary of the Invention [Problem to be solved by the invention]

[0005] In liquid ejection heads that eject liquid using heating elements, nozzle components with liquid ejection ports are layered on a substrate. If contaminants are present on the substrate, they can hinder adhesion between the substrate and the layered components. Therefore, to improve adhesion, contaminants on the substrate may be removed by some method before layering. One method for removing organic contaminants is oxygen plasma ashing. Ashing involves generating oxygen plasma, causing oxygen radicals to react with organic matter, which then decomposes into CO2 and H2O, vaporizing them and removing the organic matter. Another method for increasing the removal rate involves applying an RF bias to linearly collide oxygen ions with the target material, accelerating the reaction.

[0006] When ashing is performed on a liquid ejection head using the SiCN film disclosed in Patent Document 2 as a protective layer, the surface layer of the SiCN film reacts with oxygen radicals and / or oxygen ions. This results in the formation of a layer with an increased oxygen content compared to bulk SiCN, exceeding 20 atomic % in terms of elemental composition. Hereinafter, this layer will be referred to as the altered layer. Conventionally, SiCN films have had sufficiently high resistance to dissolution in a variety of ejection liquids, but it has been confirmed that the altered layer has lower resistance to dissolution compared to bulk SiCN. It is estimated that qualitatively, when an altered layer is formed on the surface of other Si-based films by oxygen ashing, they become more susceptible to dissolution in the ejection liquid, similar to the above.

[0007] When the altered layer on the surface of the SiCN layer that has been ashed dissolves, a lift may occur at the edge of the laminate (see Figure 2). It is believed that this occurs as the dissolution of the altered layer 3a progresses, causing erosion down to the altered layer below the laminate, resulting in the formation of the lifted portion 8.

[0008] The present disclosure provides a method for treating heat generating elements and circuits on a substrate by performing oxygen ashing or the like. The present invention provides a method for manufacturing a liquid ejection head, and a liquid ejection head, in which the protective layer has high adhesion to a laminated member on the protective layer even when a deteriorated layer is formed on the protective layer. [Means for solving the problem]

[0009] The present disclosure provides a substrate, a protective layer covering at least a portion of the substrate; and A laminated member formed on the protective layer A method for manufacturing a liquid ejection head, comprising: forming the protective layer on at least a portion of the substrate; and forming the laminated member on the protective layer so that a portion of the protective layer is exposed; the protective layer contains at least Si and C; the oxygen content in the bulk of the protective layer is less than 20 atomic % in terms of elemental composition ratio; a modified layer having an oxygen content of 20 atomic % or more in terms of elemental composition ratio is present on the surface of the protective layer, The present invention relates to a method for manufacturing a liquid ejection head in which the thickness of the altered layer between the protective layer and the laminated member is 3.40 nm or less.

[0010] Another aspect of the present disclosure is a substrate; a protective layer covering at least a portion of the substrate; and A laminated member formed on the protective layer A liquid ejection head having the laminated member is provided so as to form an exposed portion in which a part of the protective layer is exposed, the protective layer contains at least Si and C; the oxygen content in the bulk of the protective layer is less than 20 atomic % in terms of elemental composition ratio; a modified layer having an oxygen content of 20 atomic % or more in terms of elemental composition ratio is present on the surface of the protective layer, The present invention relates to a liquid ejection head in which the thickness of the altered layer between the protective layer and the laminated member is 3.40 nm or less. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a method for manufacturing a liquid ejection head that has high adhesion between a protective layer and a laminated member on the protective layer, even when a deteriorated layer is formed on the protective layer for a substrate, a heating element, a circuit, etc., by performing oxygen ashing, etc. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing an embodiment of a liquid ejection head; [Figure 2] Cross-sectional view illustrating the occurrence of a raised portion [Figure 3] Cross-sectional views showing the manufacturing process of the liquid ejection head [Figure 4] Cross-sectional views showing the manufacturing process of the liquid ejection head [Figure 5] Cross-sectional view illustrating the occurrence of a raised portion [Figure 6] 10A and 10B are cross-sectional views showing a bump manufacturing process for an electrode pad portion of a liquid ejection head; DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, specific examples of embodiments for carrying out this disclosure will be described with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in this embodiment may be changed as appropriate depending on the configuration of the components to which the disclosure is applied and various conditions. In other words, it is not intended to limit the scope of this disclosure to the following embodiments.

[0014] In the present disclosure, unless otherwise specified, the expressions "XX to YY" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way.

[0015] An inkjet head will be used as an example of application to a liquid ejection head, but the scope of application of the liquid ejection head is not limited thereto. FIG. 1 is a cross-sectional view showing an example of the configuration of a liquid ejection head. A substrate 1 has an element surface 2 including heating elements and circuits, and a protective layer 3 for protecting the element surface 2 is formed thereon. A back surface protective layer 21 for protecting the substrate is formed on the surface 1a of the substrate 1 opposite the element surface 2. A liquid supply port 4 for supplying ejection liquid (e.g., ink) is formed in the substrate 1, and a sidewall protective layer 5 is formed on the sidewall as a laminated member. A portion of the protective layer 3 is opened, exposing an electrode pad 13 electrically connected to the heating element. A laminated member including an electrode layer 15 and an adhesive layer 14 is formed as a bump on a portion of the protective layer 3 and the electrode pad 13.

[0016] The sidewall protective layer 5 is formed so that a portion thereof covers a portion of the protective layer 3, preventing the discharge liquid from eroding the element surface 2. A discharge port forming member 6 is laminated on the protective layer 3 as a laminated member. The discharge port forming member 6 has some mechanical structure, such as a liquid flow path, and has discharge ports 7 for discharging liquid. An adhesive 22 is laminated on the back surface protective layer 21 as a laminated member, and a bonding substrate 30 is bonded to the laminated member. Examples of the laminated member include the sidewall protective layer 5, the discharge port forming member 6, the adhesion layer 14, the electrode layer 15, and the adhesive 22. The laminated member is provided to form bumps including a protective layer exposed portion 20 where a portion of the protective layer 3 is exposed on the protective layer 3, a back surface protective layer exposed portion 23 where a portion of the back surface protective layer 21 is exposed on the back surface protective layer 21, the diffusion prevention layer 14, and the electrode layer 15. The laminated member can also be used as a flow path member for forming a liquid flow path.

[0017] The material of the substrate 1 is not particularly limited, and any known substrate for a liquid ejection head may be used. For example, the substrate 1 may be a silicon substrate. The protective layer 3 and the back surface protective layer 21 prevent the element surface 2 and the surface 1a from being exposed to the ejection liquid, respectively. The material must be insoluble in the ejection liquid and have high adhesion to the material (e.g., organic resin) contained in the ejection port forming member 6 and the adhesive 22. The protective layer 3 and the back surface protective layer 21 include at least Si and C as such materials. For example, silicon carbide-based compounds may be used.

[0018] The protective layer 3 and the back surface protective layer 21 preferably include at least one selected from the group consisting of a SiC film, a SiCN film, a SiOC film, and a SiOCN film. When a SiOC film or a SiOCN film is selected, the oxygen content in the bulk must be less than 20 atomic % in terms of elemental composition ratio. More preferably, the back surface protective layer 21 is a SiC film, and the protective layer 3 is a SiCN film. The SiCN film is preferably a Si x C y N z (x+y+z=100, 30≦x≦60, y≧5, z≧15 (more preferably 40≦x≦55, 5≦y≦15, 30≦z≦50)). The protective layer 3 and the back surface protective layer 21 can be formed by a known method such as a CVD method.

[0019] The oxygen content in the bulk of the protective layer is less than 20 atomic % in terms of elemental composition ratio. The "bulk of the protective layer" refers to the homogeneous composition portion inside the protective layer excluding the surface vicinity of the protective layer.

[0020] The sidewall protective layer 5 as a laminate member has the function of preventing the substrate 1 and the element surface 2 from being corroded by exposure to the discharged liquid. The sidewall protective layer 5 as a laminate member preferably contains, as a material, an oxide of at least one metal selected from the group consisting of Ti, Zr, Hf, V, Nb, and Ta. In other words, the laminate member preferably contains a metal oxide. Preferably, it is TiO. Alternatively, it may be a silicon carbide-based compound containing Si and C, similar to the protective layer 3. The sidewall protective layer 5 can be formed by a known method such as atomic phase epitaxy. There are no particular limitations on the thickness of the sidewall protective layer 5, but it is preferably 10 to 200 nm, and more preferably 50 to 150 nm.

[0021] The discharge port forming member 6 as a laminated member preferably contains an organic resin. Known organic resins used for discharge port forming members of liquid discharge heads can be used as the organic resin. For example, epoxy resins can be used, and photosensitive resins such as photosensitive epoxy resins are preferred. Specific examples include bisphenol A and F epoxy resins; phenol novolac epoxy resins; cresol novolac epoxy resins; and polyfunctional epoxy resins having a norbornene skeleton, a terpene skeleton, a dicyclopentadiene skeleton, or an oxycyclohexane skeleton.

[0022] The adhesion layer 14 as a laminated member preferably includes at least one selected from the group consisting of a Ti film, a TiW film, a TiN film, a Ta film, a TaN film, and a Cr film, and more preferably includes a TiW film. When the adhesive layer contains the above film, the adhesiveness between the electrode layer 15 and the protective layer 13 can be improved.

[0023] The adhesive 22 as a lamination member preferably contains an organic resin. As the organic resin, a known adhesive used for Si substrates can be used. For example, benzocyclobutene resin can be used.

[0024] The electrode pad 13 preferably contains a noble metal, such as gold, silver, platinum, palladium, rhodium, iridium, ruthenium, osmium, and rhenium, with iridium being particularly preferred. The electrode layer 15 as a laminated member is preferably a film containing a noble metal, such as an Au film, an Ag film, a Pt film, a Pd film, a Rh film, an Ir film, a Ru film, an Os film, or a Re film, with an Au film being particularly preferred.

[0025] The materials of the laminated member mentioned above can be used in any combination. The laminated member preferably includes an Au film and a TiW film.

[0026] If contamination is present on the protective layer 3 or the back surface protective layer 21, adhesion will be reduced at the interfaces between the protective layer 3 and the sidewall protective layer 5, the ejection port forming member 6, and the adhesion layer 14, or at the interface between the back surface protective layer 21 and the adhesive 22, or at the interface between the protective layer 3 and the adhesion layer 14, resulting in interfacial peeling. To prevent this, the contamination must be removed by some method. This type of contamination includes organic contamination, such as peeling residues generated in processes such as removing mask resist during silicon processing. One method for removing this organic contamination is oxygen plasma ashing. By performing oxygen ashing on the protective layer 3 or the back surface protective layer 21 and removing the organic contamination, the interfacial peeling described above can be prevented.

[0027] However, when ashing is performed on the protective layer 3, oxygen radicals and / or oxygen ions react not only with organic contaminants but also with the surface of the protective layer 3. As a result, an altered layer 3a is formed on the surface of the protective layer 3 (FIG. 2(a)). Silicon-based compounds with an increased oxygen content have lower resistance to dissolution by the discharge liquid compared to normal compounds, and as the presumed mechanism described above suggests, lifted portions 8 may occur at the edges of the sidewall protective layer 5, discharge port forming member 6, and adhesion layer 14 (FIGS. 2(b) and 2(c)). A similar mechanism may also cause lifted portions to occur at the edges of the adhesive 22 in the back surface protective layer 21 (FIG. 5).

[0028] The thickness of the affected layer 3a is measured by ellipsometry. When measuring the thickness of the ashed protective layer 3 or back surface protective layer 21 using this method, it is known that a good fit can be achieved by creating an optical model with an SiO layer as the outermost layer. This SiO layer is referred to as the affected layer 3a, and its thickness is the thickness of the affected layer 3a. The thickness of the affected layer 3a is measured at nine points within the surface and the average value is calculated.

[0029] Specifically, the thickness of the altered layer 3a is determined using the following method. The thickness of a protective layer, such as a SiCN film, is measured using a film thickness measurement device based on a spectroscopic ellipsometer. Analysis is then performed using the Tauc-Lorentz model, which is commonly used in spectroscopic ellipsometers. Depositing a film on a substrate does not necessarily result in a simple single-layer film. The surface of the deposited film may be uneven, discontinuous, or contain an oxide layer. Such a surface is analyzed using an optical model assuming a single SiO layer on the outermost surface, and the thickness of the resulting SiO layer is considered to be the thickness of the altered layer 3a.

[0030] The oxygen content in elemental composition ratio in the bulk of the protective layer or the altered layer 3a is confirmed by the following method. The composition of the surface of the protective layer is analyzed using X-ray photoelectron spectroscopy (XPS). The photoelectron spectrum obtained by irradiating with X-rays is analyzed to measure the elemental composition ratio that makes up the protective layer. When measuring the bulk, sputtering using Ar is performed as appropriate to expose the bulk for measurement.

[0031] Here, an experiment was conducted to investigate the relationship between the thickness of the altered layer 3a and the occurrence of lifting at the edge of the laminate. First, a 150 nm SiCN film, which was assumed to be the protective layer 3, was formed on a silicon substrate by CVD. Next, the thickness of the altered layer 3a after ashing and other processes was measured, and a 80 nm TiO film, which was assumed to be the sidewall protective layer 5, was formed on top of it by atomic layer deposition (ALD). nm film was deposited.

[0032] The photoresist applied to the TiO film was then patterned, and the TiO film was etched with buffered hydrofluoric acid to form square TiO patterns with sides of 40 μm. The substrate was then cut into individual pieces to include the TiO patterns, and the individual pieces were immersed in ink heated to 121°C for three weeks. The lifting of the edges of the TiO patterns was examined under a microscope. The results are shown in Table 1. From these results, it was estimated that the thickness of the altered layer 3a has a threshold value for lifting of the TiO film, and that the thinner the thickness of the altered layer 3a, the less likely the TiO film will lift.

[0033] In Table 1, for samples A, B, D, and M, the altered layer was removed by reverse sputtering after the SiCN film was formed and before ashing. For samples G and H, the altered layer was removed by ashing after the SiCN film was formed and then etching with buffered hydrofluoric acid. For samples C, E, and F, the altered layer was removed by reverse sputtering after the SiCN film was formed and before ashing, and then part of the altered layer was removed by etching with buffered hydrofluoric acid after ashing. [Table 1]

[0034] The reason why TiO is less likely to float as the thickness of the altered layer 3a decreases is presumed to be as follows: The sidewall protective layer 5, ejection port forming member 6, and adhesion layer 14, which are laminated members, are formed on the protective layer 3, and at that time, an exposed portion 20, where part of the protective layer is exposed, is also formed (FIG. 2(b)). As a result, when the liquid ejection head is in use, the exposed portion 20 is exposed to liquids such as ink.

[0035] As shown by the vertical arrows in Figure 2(c), first, dissolution of the altered layer 3a progresses vertically from the surface exposed to the ink, revealing a cross-section of the altered layer 3a along the edge of the TiO pattern. As this cross-section is exposed to ink, dissolution also progresses in the cross-sectional direction (horizontal arrows). However, the thinner the altered layer 3a, the narrower the ink passage becomes, slowing the ink's progress in the cross-sectional direction and reducing the dissolution rate. Furthermore, once the layer becomes thinner than a certain thickness, dissolution stops, and the TiO film does not lift (Figures 2(a)', (b)', and (c)').

[0036] It was also found that the thickness of the altered layer 3a depends on the ashing conditions, particularly the stage temperature, processing time, and RF bias power during ashing. Sample B in Table 1 was ashed for one minute at a stage temperature of 60°C, while sample D was ashed for one minute at a stage temperature of 250°C. This shows that the higher the stage temperature, the thicker the altered layer 3a formed by ashing.

[0037] Here, no RF bias was applied during ashing for either Sample B or Sample D. Sample M was ashed with an RF bias power of 120 W applied at a stage temperature of 16°C. Although the stage temperature was lower than for Samples B and D, the thickness of the affected layer 3a was greater than for those two. This shows that the greater the RF bias power, the thicker the affected layer 3a.

[0038] From the above, it was found that the thickness of the affected layer 3a depends on the stage temperature and RF bias power during ashing, but it is also believed that the RF bias power has a greater effect on the thickness of the affected layer than the stage temperature. From this, it is presumed that the mechanism of formation of the affected layer 3a differs between ashing without applying an RF bias and ashing with an applied RF bias.

[0039] In ashing without RF bias, oxygen radicals react with the surface of the SiCN film. At this time, the oxygen radicals replace the constituent elements C and N, and the oxygen content gradually increases in the thickness direction. It is estimated that this increases, forming an altered layer 3a. On the other hand, in ashing with an RF bias applied, in addition to the reaction of oxygen radicals, oxygen ions also collide linearly with the film surface and react. If the acceleration energy of the oxygen ions toward the substrate due to the RF bias is greater than the interatomic bond energy of the film surface, the interatomic bonds are broken upon collision, and the atoms that make up the film are ejected.

[0040] Oxygen accumulates in the ejected areas, and it is estimated that the resulting altered layer 3a has a more disordered composition and a lower density than the altered layer 3a formed by a reaction with only oxygen radicals. At the same time, if the acceleration energy of the oxygen ions toward the substrate is smaller than the interatomic bond energy on the film surface, the mechanism of altered layer formation will be the same as when no RF bias is applied, and it is estimated that the altered layer 3a can be made thinner.

[0041] The acceleration energy of oxygen ions onto the substrate is determined by the effective voltage Vdc acting between the oxygen plasma and the sample when an RF bias is applied. Therefore, it is estimated that the thickness of the altered layer 3a can be suppressed by controlling Vdc and keeping it below a certain value. In this case, for example, when ashing a SiCN film, the bond energies of the Si-C bond and Si-N bond, which are the main interatomic bonds of the film, are approximately 100 eV and approximately 102 eV, respectively, so it is thought that Vdc should be set to less than 100 V.

[0042] Based on the above-mentioned estimated mechanism and the results in Table 1, it was estimated that optimizing the ashing conditions to make the thickness of the altered layer 3a 3.40 nm or less is effective. The thickness of the altered layer 3a is preferably 3.20 nm or less, more preferably 3.00 nm or less, even more preferably 2.00 nm or less, even more preferably 1.50 nm or less, especially preferably 1.00 nm or less, even especially preferably 0.50 nm or less, and particularly preferably 0.10 nm or less. There is no particular lower limit, and the thinner the better, but for example, preferably 0.01 nm or more, 0.02 nm or more, or 0.03 nm or more.

[0043] Examples of appropriate ashing conditions include ashing without applying an RF bias, or ashing with an RF bias power that makes Vdc less than 100 V. The ashing conditions may be appropriately selected from the following ranges, for example, so that the thickness of the affected layer 3a becomes less than 3.40 nm.

[0044] The microwave power is preferably 500 to 2000 W, more preferably 800 to 1500 W. The oxygen gas flow rate at 25°C is preferably 100 to 1000 sccm, more preferably 200 to 600 sccm. The process pressure is preferably 20 to 200 Pa, more preferably 40 to 100 Pa. The stage temperature is preferably 5 to 400°C, more preferably 10 to 300°C. The treatment time is preferably 10 to 600 seconds, more preferably 30 to 400 seconds. When an RF bias is applied, the RF bias power may be appropriately selected, for example, preferably in the range of 20 W or less, so that Vdc is less than 100 V.

[0045] Even when ashing is performed to a state where the thickness of the altered layer 3a exceeds 3.40 nm, it is estimated that it is effective to perform another process to reduce the thickness of the altered layer 3a to 3.40 nm or less. In this case, the altered layer 3a may be completely removed. That is, the thickness of the altered layer 3a can be set to 0.00 nm or more and 3.40 nm or less. In this case, it is preferable to use a method that does not cause contamination such as organic contamination on the protective layer 3.

[0046] For example, the altered layer 3a formed by ashing may be etched with hydrofluoric acid. That is, after the ashing process, the protective layer 3 on which the altered layer 3a is formed is etched. Preferably, a step of etching is performed to remove at least a portion of the altered layer 3a. Etching using hydrofluoric acid, such as buffered hydrofluoric acid, as an etching solution is more preferred. The etching method is not particularly limited, and known methods such as spin etching can be used. The etching time is not particularly limited, and is preferably 10 to 200 seconds, and more preferably 30 to 100 seconds. The etching conditions are not particularly limited as long as they are adjusted so that the thickness of the altered layer 3a can be controlled within a specific range. For example, in the case of spin etching, etching is performed with an etching solution flow rate of 2.0 L / min and a wafer rotation speed of 1000 rpm.

[0047] Furthermore, reverse sputtering can be used as a means for removing the altered layer 3a. That is, it is preferable to employ a step of performing reverse sputtering on the protective layer 3 on which the altered layer 3a has been formed after the ashing step, thereby removing at least a portion of the altered layer 3a. For example, reverse sputtering using an inert gas such as Ar can be used. The conditions for reverse sputtering are not particularly limited as long as they are adjusted so that the thickness of the altered layer 3a can be controlled within a specific range, but examples include an Ar gas flow rate of 30 sccm and a process time of 25.9 seconds.

[0048] Furthermore, for example, when the temperature during film formation is high, such as 400°C, the protective layer 3 may have an altered layer 3a on its surface at the time of film formation. In such cases, it is effective to control the thickness of the altered layer 3a to 3.40 nm or less by removing the altered layer 3a in advance using some method. That is, it is preferable to include a step of removing at least a portion of the altered layer 3a before the step of forming the laminate member, and it is preferable to control the thickness of the altered layer 3a to 3.40 nm or less in the step of removing at least a portion of the altered layer 3a.

[0049] The removal method for the step of removing at least a portion of the altered layer 3a may be, for example, etching or reverse sputtering. The etching and reverse sputtering are as described above. After removing the altered layer, an ashing step may be employed, if necessary, in which the surface of the protective layer is ashed while controlling the thickness of the altered layer 3a to 3.40 nm or less.

[0050] Through the above steps, a liquid ejection head is provided. That is, it is preferable that the method for manufacturing a liquid ejection head includes an ashing step of ashing the surface of the protective layer before the step of forming the laminated member, and that the altered layer is formed by the ashing step. The method for manufacturing a liquid ejection head includes the steps of: substrate, a protective layer covering at least a portion of the substrate; and A laminated member formed on the protective layer A method for manufacturing a liquid ejection head, comprising: forming the protective layer on at least a portion of the substrate; an ashing step of ashing the surface of the formed protective layer; and forming the laminated member on the protective layer after the ashing step so that a portion of the protective layer is exposed; the protective layer contains at least Si and C; the oxygen content in the bulk of the protective layer is less than 20 atomic % in terms of elemental composition ratio; the ashing step forms an altered layer on the surface of the protective layer, the altered layer having an oxygen content of 20 atomic % or more in terms of elemental composition ratio; Preferably, the method for manufacturing a liquid ejection head is characterized in that the thickness of the altered layer between the protective layer and the laminated member is 3.40 nm or less.

[0051] The liquid ejection head provided by the above-described process comprises a substrate, at least a part of the substrate, a protective layer covering the insulating film, and a laminated member formed on the protective layer; the laminated member is provided so as to form an exposed portion in which a part of the protective layer is exposed, the protective layer contains at least Si and C; the oxygen content in the bulk of the protective layer is less than 20 atomic % in terms of elemental composition ratio; a modified layer having an oxygen content of 20 atomic % or more in terms of elemental composition ratio is present on the surface of the protective layer, The thickness of the altered layer between the protective layer and the laminated member is preferably 3.40 nm or less.

[0052] In the following embodiment, an example of a liquid ejection head will be shown as a more specific example of application to a device.

[0053] Example 1 In this embodiment, an example of a liquid ejection head is shown in which the thickness of the altered layer 3a on the surface of the protective layer is controlled to 3.40 nm or less by optimizing the ashing conditions.

[0054] First, a silicon substrate 1 with a thickness of 625 μm was prepared (FIG. 3(a)). One side of this silicon substrate 1 (hereinafter referred to as the front side) had an element surface 2 on which heating elements and circuits for driving them were formed, and a SiCN film (Si x C y N z In this example, x=47, y=11, z=42) was formed in advance. A part of a liquid flow path 10 having a depth of approximately 500 μm was formed on the other surface 1a of the substrate 1 opposite to the surface on which the element surface 2 was formed. A liquid supply port 4 was also formed from the surface of the substrate 1, communicating with the liquid flow path 10. No altered layer 3a was formed on the surface of the protective layer 3 of this laminate.

[0055] Next, ashing was performed on the surface of the substrate 1 using an ashing device (MAS-8220AT) as cleaning before forming the sidewall protective layer 5. Based on the results in Table 1 and the presumed mechanism described above, two ashing conditions were selected: one in which no RF bias was applied, and one in which Vdc was less than 100 V. Details of the two conditions are given below.

[0056] In one case, oxygen plasma was generated at a microwave power of 1200 W, an oxygen gas flow rate of 500 sccm (25°C), and a process pressure of 80 Pa, and treatment was performed for 60 seconds at a stage temperature of 250°C without applying an RF bias (hereinafter referred to as condition 1). The thickness of the affected layer 3a at this time was 2.17 nm.

[0057] The other was treated for 60 seconds with oxygen plasma generated at a microwave power of 1000 W, an oxygen gas flow rate of 400 sccm (25°C), and a process pressure of 60 Pa, with an RF bias power of 20 W applied and a stage temperature of 16°C (hereinafter referred to as condition 2). Vdc when an RF bias of 20 W was applied was 81.6 V. The thickness of the affected layer 3a at this time was 2.95 nm.

[0058] For comparison, ashing was also performed under conditions where Vdc was 100 V or higher. The details of the conditions are as follows: Oxygen plasma was generated at a microwave power of 1000 W, an oxygen gas flow rate of 400 sccm (25°C), and a process pressure of 60 Pa, and an RF bias power of 120 W was applied, with the treatment performed for 60 seconds at a stage temperature of 16°C (hereinafter referred to as condition 3). Vdc was 320 V when an RF bias of 120 W was applied. The thickness of the affected layer 3a at this time was 5.67 nm.

[0059] Next, a sidewall protection layer is formed on the protection layer 3 by atomic layer deposition (ALD method). An 80 nm TiO film was formed as the protective layer 5 (Fig. 3(b)). Then, a film of photoresist was laminated on the surface of the substrate 1, and a photomask and exposure device were used to form a photoresist pattern 11 only around the liquid supply port (Fig. 3(c)). Next, using the pattern 11 as a mask, unnecessary portions of the sidewall protective layer 5 on the surface of the substrate 1 were etched. Buffered hydrofluoric acid was used as the etching solution. The photoresist pattern 11 used as the mask was then removed.

[0060] Next, the photosensitive epoxy resin film is laminated, exposed to light, and developed twice. This forms a discharge port forming member 6 on the protective layer on the front side of the substrate 1, thereby forming liquid discharge ports 7 and liquid flow paths 12 from the liquid supply ports 4 to the liquid discharge ports 7, completing the liquid discharge head (FIG. 3(d)). The portions of the protective layer 3 where the discharge port forming member 6 and the sidewall protective layer 5 are not present become exposed portions 20.

[0061] Finally, the liquid ejection head was divided into individual pieces, and the individual pieces were immersed in ink heated to 121°C for three weeks, after which the adhesion interface between the protective layer 3 and the ejection port forming member 6 was observed under a microscope. At this time, no lifting due to dissolution of the altered layer 3a was observed in either the substrates ashed under conditions 1 or 2. In contrast, lifting due to dissolution of the altered layer 3a was observed in the substrate ashed under condition 3.

[0062] Example 2 This example shows an example of a liquid ejection head in which the thickness of the altered layer 3a formed on the surface of the protective layer 3 by ashing is controlled to 3.40 nm or less by removing the altered layer 3a in a subsequent process. First, a laminate having the same liquid supply port 4 and liquid flow path 10 as in Example 1 was prepared, and ashing was performed on the surface of the substrate 1 as cleaning before forming the sidewall protective layer 5. The ashing was performed by generating oxygen plasma at a microwave power of 1000 W, an oxygen gas flow rate of 400 sccm (25°C), and a process pressure of 60 Pa, applying an RF bias power of 120 W, and performing the process at a stage temperature of 16°C for 60 seconds. Vdc was 320 V when the RF bias was applied at 120 W. The thickness of the altered layer 3a was 5.67 nm.

[0063] Thereafter, etching with buffered hydrofluoric acid was carried out for 60 seconds using a spin etching method in which an etching solution was dropped while rotating the substrate 1. The thickness of the altered layer 3a at this time was 2.97 nm.

[0064] Next, a sidewall protective layer 5 was formed and patterned in the same manner as in Example 1. All subsequent processes were similar to those in Example 1. Finally, the liquid ejection head was divided into individual pieces, and the individual pieces were immersed in ink heated to 121°C for three weeks, after which the adhesive interface between the protective layer 3 and the ejection port forming member 6 was checked under a microscope. At this time, no lifting due to dissolution of the altered layer 3a was observed.

[0065] Example 3 This example shows an example of a liquid ejection head in which the thickness of the altered layer 3a formed on the surface of the protective layer 3 at the time of film formation is controlled to 3.40 nm or less by previously removing the altered layer 3a. First, as in Example 1, a laminate in which a liquid supply port 4 and a liquid flow path 10 are formed was prepared. At this time, the protective layer 3 had an altered layer 3a on its surface at the time of film formation. At this time, the thickness of the altered layer 3a was 3.85 nm. This altered layer 3a was previously removed by reverse sputtering using Ar (conditions: Ar gas flow rate 30 sccm, process time 25.9 s). At this time, the film thickness of the altered layer 3a was 1.21 nm.

[0066] Next, ashing was performed on the surface of the substrate 1 as cleaning before forming the sidewall protective layer 5. The ashing was performed at a microwave power of 1200 W and an oxygen gas flow rate of 500 sccm. Oxygen plasma was generated at a process pressure of 80 Pa (25° C.), and the treatment was carried out for 60 seconds at a stage temperature of 250° C. without applying an RF bias. The thickness of the affected layer 3a at this time was 2.17 nm.

[0067] Next, a sidewall protective layer 5 was formed and patterned in the same manner as in Example 1. All subsequent processes were similar to those in Example 1. Finally, the liquid ejection head was divided into individual pieces, and the individual pieces were immersed in ink heated to 121°C for three weeks, after which the adhesive interface between the protective layer 3 and the ejection port forming member 6 was checked under a microscope. At this time, no lifting due to dissolution of the altered layer 3a was observed.

[0068] Example 4 This example focuses on the adhesion between the back surface protective layer 21 and the adhesive 22 when forming the adhesive 22 on the back surface protective layer 21. This example shows an example of a liquid ejection head in which the thickness of the altered layer 21a of the back surface protective layer 21 formed by ashing is controlled to 3.40 nm or less. As in Example 1, a laminate in which a liquid supply port 4 and a liquid flow path 10 are formed was prepared. Next, as in Example 1, a sidewall protective layer 5 was formed. Thereafter, a 50 nm SiC film was formed as the back surface protective layer 21 on the surface 1a opposite the element surface 2 by CVD, and patterning was performed (FIG. 4(a)).

[0069] Next, the rear surface protection layer 21 was subjected to ashing as cleaning before forming the adhesive 22. The ashing was performed under condition 1. The thickness of the altered layer 21a at this time was 4.44 nm.

[0070] Thereafter, spin etching is performed by dropping an etching solution onto the surface 1a of the substrate 1 while rotating the substrate 1. The resulting altered layer 21a was etched with buffered hydrofluoric acid for 60 seconds using a method described above, and the thickness of the altered layer 21a was 1.21 nm.

[0071] Next, a film of adhesive 22 was laminated on back surface protective layer 21 (FIG. 4(b)), and a bonding substrate 30 to be bonded to substrate 1 was bonded thereto (FIG. 4(c)). After bonding, the bonding was performed by baking at 250°C for 1 hour to harden adhesive 22. The portion of back surface protective layer 21 where adhesive 22 was not present became exposed back surface protective layer portion 23.

[0072] Finally, the liquid ejection head was divided into individual pieces, and the individual pieces were immersed in ink heated to 121°C for three weeks, after which the adhesive interface between the back surface protective layer 21 and the adhesive material 22 was checked under a microscope. At this time, no lifting due to dissolution of the altered layer 21a was observed.

[0073] Example 5 This example focuses on the adhesion between the protective layer and the bump when forming the bump on the electrode pad of the liquid ejection head. As in Example 1, by optimizing the ashing conditions, the thickness of the altered layer 3a on the surface of the protective layer is controlled to 3.40 nm or less.

[0074] First, a silicon substrate 1 having a thickness of 625 μm was prepared (FIG. 6(a)). On one side of this silicon substrate 1, a heat generating element and a circuit for driving the element (not shown) were formed, and a SiCN film (Si x C y N z In this example, x=47, y=11, z=42) was formed in advance. A portion of the protective layer 3 was opened to expose an electrode pad 13 electrically connected to the heating element. The electrode pad 13 was made of a noble metal such as iridium. No altered layer 3a was formed on the surface of the protective layer 3 of this laminate.

[0075] Next, as a cleaning before forming bumps on a part of the protective layer 3 and the electrode pads 13, ashing was performed on the surface of the substrate 1 using an ashing device (MAS-8220AT). The ashing conditions at this time were determined based on the results in Table 1 and the estimated mechanism described above, and were as follows: RF Two conditions were selected: no bias was applied and Vdc was less than 100 V. Details of the two conditions are shown below.

[0076] In one case, oxygen plasma was generated at a microwave power of 1200 W, an oxygen gas flow rate of 500 sccm (25°C), and a process pressure of 80 Pa, and treatment was performed for 60 seconds at a stage temperature of 250°C without applying an RF bias (hereinafter referred to as condition 1). The thickness of the affected layer 3a at this time was 2.17 nm.

[0077] The other was treated for 60 seconds with oxygen plasma generated at a microwave power of 1000 W, an oxygen gas flow rate of 400 sccm (25°C), and a process pressure of 60 Pa, with an RF bias power of 20 W applied and a stage temperature of 16°C (hereinafter referred to as condition 2). Vdc when an RF bias of 20 W was applied was 81.6 V. The thickness of the affected layer 3a at this time was 2.95 nm.

[0078] For comparison, ashing was also performed under conditions where Vdc was 100 V or higher. The details of the conditions are as follows: Oxygen plasma was generated at a microwave power of 1000 W, an oxygen gas flow rate of 400 sccm (25°C), and a process pressure of 60 Pa, and an RF bias power of 120 W was applied, with the treatment performed for 60 seconds at a stage temperature of 16°C (hereinafter referred to as condition 3). Vdc was 320 V when an RF bias of 120 W was applied. The thickness of the affected layer 3a at this time was 5.67 nm.

[0079] Next, bumps are formed on a portion of the protective layer 3 and the electrode pads 13. First, the adhesion layer 14 and the electrode layer 15 are successively formed using a vacuum film-forming apparatus. Here, the adhesion layer 14 is formed using titanium tungsten to a thickness of 200 nm. The electrode layer 15 is formed using gold to a thickness of 400 nm (FIG. 6(b)). Then, photoresist is applied to the surface of the substrate 1, and a photoresist pattern 11 is formed only around the periphery of the electrode pad using a photomask and an exposure apparatus (FIG. 6(c)). Next, using the pattern 11 as a mask, the electrode layer 15 and the adhesion layer 14 are etched to form bumps in the desired shape (FIG. 6(d)). The electrode layer 15 is etched using an etching solution mainly composed of iodine and potassium iodine. The adhesion layer 14 is etched using an etching solution mainly composed of hydrogen peroxide. The photoresist pattern 11 used as a mask is then removed.

[0080] Finally, the liquid ejection head was divided into individual pieces, and the individual pieces were immersed in ink heated to 121°C for three weeks, after which cross-sectional SEM observation was performed to confirm the interface between the protective layer 3 and the adhesive layer 14. In this case, no lifting due to dissolution of the altered layer 3a was observed in either the substrates ashed under conditions 1 or 2. In contrast, lifting due to dissolution of the altered layer 3a was observed in the substrate ashed under condition 3.

[0081] Example 6 In this example, a liquid ejection head is shown in which the thickness of the altered layer 3a formed on the surface of the protective layer 3 by ashing is controlled to 3.40 nm or less by removing the altered layer 3a in a subsequent process. First, a substrate with a portion of the protective layer 3 opened to expose the electrode pads 13 was prepared as in Example 4. Ashing was performed on the surface of the substrate 1 as a cleaning step prior to the deposition of the adhesion layer 14 and electrode layer 15. For this ashing, oxygen plasma was generated at a microwave power of 1000 W, an oxygen gas flow rate of 400 sccm (25°C), and a process pressure of 60 Pa. An RF bias power of 120 W was applied, and the process was performed for 60 seconds at a stage temperature of 16°C. Vdc was 320 V when the RF bias was applied at 120 W. The thickness of the altered layer 3a was 5.67 nm.

[0082] Then, the substrate 1 is rotated while an etching solution is dropped onto the substrate 1 by a spin etching method. Then, etching with buffered hydrofluoric acid was carried out for 60 seconds, and the thickness of the altered layer 3a at this time was 2.97 nm.

[0083] Next, the adhesion layer 14 and the electrode layer 15 were formed in the same manner as in Example 5, and bumps were formed. All subsequent processes were similar to those in Example 5. Finally, the liquid ejection head was divided into individual pieces, and the individual pieces were immersed in ink heated to 121°C for three weeks, after which cross-sectional SEM observation was performed to confirm the interface between the protective layer 3 and the adhesion layer 14. At this time, no lifting due to dissolution of the altered layer 3a was observed. [Explanation of symbols]

[0084] 1 substrate, 2 element surface on which heat generating elements and drive circuits are formed, 3 protective layer, 4 liquid supply port, 5 sidewall protective layer, 6 discharge port forming member, 7 liquid discharge port, 8 lifting of laminate edge, 10 Liquid flow path, 11 mask photoresist, 12 liquid flow path, 13 electrode pad, 14 adhesion layer, 15 electrode layer, 20 exposed portion of protective layer, 21 back surface protective layer, 22 adhesive material, 23 exposed portion of back surface protective layer, 30 bonding substrate

Claims

1. substrate, a protective layer covering at least a portion of the substrate; and A laminated member formed on the protective layer A method for manufacturing a liquid ejection head, comprising: forming the protective layer on at least a portion of the substrate; and forming the laminated member on the protective layer so that a portion of the protective layer is exposed; the protective layer contains at least Si and C; the oxygen content in the bulk of the protective layer is less than 20 atomic % in terms of elemental composition ratio; a modified layer having an oxygen content of 20 atomic % or more in terms of elemental composition ratio is present on the surface of the protective layer, A method for manufacturing a liquid ejection head, wherein the thickness of the altered layer between the protective layer and the laminated member is 3.40 nm or less.

2. an ashing step of ashing a surface of the protective layer before the step of forming the laminated member, The method for manufacturing a liquid ejection head according to claim 1 , wherein the altered layer is formed by the ashing step.

3. 3. The method for manufacturing a liquid ejection head according to claim 2, wherein in the ashing step, the surface of the protective layer is ashed by an ashing method in which no RF bias is applied or Vdc is less than 100V.

4. The method for manufacturing a liquid ejection head according to claim 1 , further comprising the step of removing at least a part of the deteriorated layer before the step of forming the laminated member.

5. 5. The method for manufacturing a liquid ejection head according to claim 1, wherein the protective layer includes at least one selected from the group consisting of a SiC film, a SiCN film, a SiOC film, and a SiOCN film.

6. the protective layer is a SiCN film, The SiCN film is Si ｘ C ｙ N ｚ 6. The method for manufacturing a liquid ejection head according to claim 1, wherein x+y+z is expressed as (x+y+z=100, 30≦x≦60, y≧5, z≧15).

7. 7. The method for manufacturing a liquid ejection head according to claim 1, wherein the laminated member contains an organic resin.

8. 7. The method for manufacturing a liquid ejection head according to claim 1, wherein the laminated member contains a metal oxide.

9. 7. The method for manufacturing a liquid ejection head according to claim 1, wherein the laminated member includes an Au film and a TiW film.

10. 10. The method for manufacturing a liquid ejection head according to claim 1, further comprising the step of removing at least a part of the altered layer by etching the protective layer before the step of forming the laminated member.

11. Before the step of forming the laminated member, the altered layer is formed by reverse sputtering the protective layer.

10. The method for manufacturing a liquid ejection head according to claim 1, further comprising a step of removing at least a part of the above.

12. substrate, a protective layer covering at least a portion of the substrate; and A laminated member formed on the protective layer A liquid ejection head having the laminated member is provided so as to form an exposed portion in which a part of the protective layer is exposed, the protective layer contains at least Si and C; the oxygen content in the bulk of the protective layer is less than 20 atomic % in terms of elemental composition ratio; a modified layer having an oxygen content of 20 atomic % or more in terms of elemental composition ratio is present on the surface of the protective layer, A liquid ejection head characterized in that the thickness of the altered layer between the protective layer and the laminated member is 3.40 nm or less.

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