JP2015201590A - Method of manufacturing substrate for liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a liquid discharge head having high mechanical strength.SOLUTION: A method of manufacturing a substrate for a liquid discharge head includes: a step (a) for forming an etching mask layer on one surface of a silicon substrate; a step (b) for performing crystal anisotropic etching on the substrate via the etching mask layer, and forming a liquid supply port until or just before reaching the other surface of the silicon substrate; and a step (c) for performing isotropic etching via the etching mask layer, further expanding the supply port and forming a corner of the supply port into a curved shape.

Description

  The present invention relates to a method for manufacturing a substrate for a liquid discharge head.

  One type of ink jet recording head that discharges ink onto a recording medium (hereinafter also referred to as “recording head”) is a type of recording head called a “side shooter type head”. In the side shooter type head, ink is discharged toward the upper side of a heater as an energy generating element that generates energy used for ink discharge. FIGS. 10A and 10B show the basic structure of the recording head substrate constituting the side shooter type head. In the recording head substrate shown in FIGS. 10A and 10B, a supply port 109 is provided in a silicon substrate 101 having an energy generating element 103 formed on the surface thereof. The supply port 109 is a hole that penetrates the silicon substrate 101, and ink is supplied from the back surface side to the front surface side of the silicon substrate 101 through the supply port 109.

A manufacturing method of a recording head substrate having the above-described structure is disclosed in Patent Document 1. Patent Document 1 discloses a manufacturing method having the following steps in order to prevent variation in the opening diameter of a supply port that is a through hole.
(A) forming a sacrificial layer capable of being selectively etched with respect to the substrate material at a supply port forming site on the surface of the silicon substrate;
(B) forming a passivation layer having etching resistance so as to cover the sacrificial layer on the silicon substrate;
(C) forming an etching mask layer having an opening corresponding to the sacrificial layer on the back surface of the silicon substrate;
(D) etching the silicon substrate by crystal anisotropic etching until the sacrificial layer is exposed from the opening of the etching mask layer;
(E) etching and removing the sacrificial layer from the exposed portion of the silicon substrate etching process;
(F) A step of removing a portion of the passivation layer to form a supply port.

  Crystal anisotropic etching employed in the step (d) is known as a technique capable of forming a supply port with high accuracy.

  Patent Document 2 discloses a manufacturing method in which dry etching is performed using an etching mask layer provided on the back surface of a silicon substrate, and then etching is performed by crystal anisotropic etching using the same etching mask layer. ing. According to this manufacturing method, the supply port having a cross section in which the width of the central portion in the substrate thickness direction in the supply port is narrowed is formed. In this manufacturing method, the etching mask layer is shared by dry etching and wet etching. Therefore, the opening width of the supply port on the back surface of the silicon substrate is determined by the opening width (mask width) of the etching mask layer formed on the back surface of the silicon substrate and the amount of dry etching. The “opening width” of the supply port means the width of the supply port in the short side direction. The “opening length” of the supply port means the width of the supply port in the long side direction.

Japanese Patent Laid-Open No. 10-181032 US Pat. No. 6,805,432

  In order to realize high-speed recording of a high-definition image, it is required to dispose the ejection ports at a high density and to dispose more ejection ports by extending the ejection port array. However, if the discharge port array is lengthened, it is necessary to increase the opening length of the supply port, and the mechanical strength of the recording head substrate decreases. When the mechanical strength of the recording head substrate decreases, the substrate may be deformed or damaged in the manufacturing process of the recording head. In particular, due to the deformation of the substrate, stress concentrates on the corner of the supply port, and cracks 117 as shown in FIG. 11 enter and cause damage. An object of the present invention is to provide a liquid discharge head substrate having high mechanical strength.

A method for manufacturing a substrate for a liquid discharge head according to the present invention includes:
(A) forming an etching mask layer on one surface of the silicon substrate;
(B) performing crystal anisotropic etching on the silicon substrate through the etching mask layer, and forming a liquid supply port until reaching or just before reaching the other surface of the silicon substrate;
(C) performing isotropic etching through the etching mask layer, further expanding the supply port, and bending the corner of the supply port;
including.

In addition, a method for manufacturing a liquid discharge head substrate according to the present invention includes:
(A) forming a sacrificial layer on one surface of the silicon substrate;
(B) forming a passivation layer having etching resistance so as to cover the sacrificial layer;
(C) forming an etching mask layer having an opening corresponding to the sacrificial layer on the other surface of the silicon substrate;
(D) performing crystal anisotropic etching on the silicon substrate via the etching mask layer to form a liquid supply port;
(E) removing the sacrificial layer;
(F) performing isotropic etching through the etching mask layer, further expanding the supply port, and bending the corner of the supply port;
(G) removing a part of the passivation layer and opening the supply port on one side of the silicon substrate;
including.

  According to the present invention, it is possible to provide a liquid discharge head substrate having high mechanical strength.

FIG. 3 is a perspective view of an example of a print cartridge including a liquid discharge head substrate according to the present invention. It is sectional drawing of an example of the board | substrate for liquid discharge heads concerning this invention. It is a side view of an example of the substrate for liquid discharge heads concerning the present invention. It is sectional drawing which shows an example of the manufacturing process of the board | substrate for liquid discharge heads which concerns on this invention. It is sectional drawing which shows an example of the manufacturing process of the board | substrate for liquid discharge heads which concerns on this invention. 4A is a top view and FIG. 4B is a cross-sectional view of a substrate on which a sacrificial layer is formed in the manufacturing process of the liquid discharge head substrate according to the present invention. FIG. 3A is a top view and FIG. 2B is a cross-sectional view of a liquid discharge head substrate according to the present invention. It is a perspective view of an example of the liquid discharge head concerning the present invention. It is sectional drawing which shows an example of the manufacturing process of the liquid discharge head which concerns on this invention. It is (A) perspective view and (B) sectional drawing of an example of the board | substrate for conventional inkjet recording heads. It is a perspective view of an example of the board | substrate for the conventional inkjet recording head.

  The method for manufacturing a substrate for a liquid discharge head according to the present invention includes: (a) a step of forming an etching mask layer on one surface of a silicon substrate; and (b) a crystal formed on the silicon substrate via the etching mask layer. Performing anisotropic etching, forming a liquid supply port until reaching or just before reaching the other surface of the silicon substrate, and (c) performing isotropic etching through the etching mask layer, Further expanding the supply port to form a corner of the supply port.

  In the method according to the present invention, after forming the supply port by crystal anisotropic etching, isotropic etching is further performed. Thereby, the corner | angular part of a supply port can be taken and it can be made into a curved shape, further expanding a supply port. Here, the corner portion of the supply port refers to a portion having a square shape, such as a corner portion of the opening portion of the supply port or a corner portion in the vicinity of the central portion in the thickness direction of the silicon substrate in the supply port. For example, as shown in FIG. 8, the corner 116 of the opening of the supply port is curved, so that the mechanical strength is high even when the opening length of the supply port is increased. It is possible to prevent stress from concentrating on the corner of the opening of the supply port and cracking the silicon substrate. Further, for example, as shown in FIG. 4 (f) and FIG. 5 (f), the corner 24 near the central portion in the thickness direction of the silicon substrate in the supply port has a curved shape, thereby preventing bubbles from remaining and supplying. Since the fluidity of the liquid such as ink in the mouth is improved, the liquid ejection performance from the ejection port in the liquid ejection head is improved. The liquid discharge head substrate obtained by the method according to the present invention is preferably used as an inkjet recording head substrate, for example.

  In addition, four isotropic (rectangular) four cross-sectional shapes of the supply port orthogonal to the thickness direction of the substrate (the direction in which the supply port extends) by isotropic etching after forming the supply port by crystal anisotropic etching Corners or corners are machined into arcs, ie curved. This arc-shaped shape is a shape in which the center of a circle including the circular arc is located inside the supply port and is curved toward the outside of the cross section of the supply port. This corner processing is performed from the vicinity of the back surface (lower surface) to the front surface (upper surface) of the substrate in the supply port. In FIGS. 7 and 8, the arc-shaped corner portion curved in the outward direction of the supply port is the substrate 101. The state which is also formed in the corner part 116 of the opening of the supply port formed on the surface of is shown.

  The method for manufacturing a substrate for a liquid discharge head according to the present invention includes (a) a step of forming a sacrificial layer on one surface of a silicon substrate, and (b) a sacrificial layer having etching resistance. Forming a layer so as to cover the layer; (c) forming an etching mask layer having an opening corresponding to the sacrificial layer on the other surface of the silicon substrate; and (d) with respect to the silicon substrate. Performing crystal anisotropic etching through the etching mask layer to form a liquid supply port; (e) removing the sacrificial layer; and (f) isotropic through the etching mask layer. Performing a characteristic etching to further expand the supply port to form a curved corner portion of the supply port; and (g) removing a portion of the passivation layer to form one of the silicon substrates. On the surface side Comprising a step of opening the supply opening, the.

  In this method, since the supply port is formed using the sacrificial layer and the passivation layer, the supply port can be formed with high accuracy. In addition, since the corner of the opening of the supply port and the corner near the center of the thickness direction of the silicon substrate in the supply port can be formed by isotropic etching, the same effect as described above can be obtained. can get.

  FIG. 1 is a schematic perspective view of an example of a print cartridge including a liquid discharge head according to the present invention as a print head. The print cartridge 10 shown in FIG. 1 includes a cartridge body 11, a print head 13, and electrical contacts 15. The cartridge body 11 includes ink supplied to the print head 13 inside. The print cartridge 10 shown in FIG. 1 is an ink cartridge-integrated disposable type, but is not limited thereto, and is a type that receives ink supply from an independent ink cartridge of another configuration disposed on the print carriage. It may be. Further, a type that receives ink from an external ink supply mechanism connected to the print cartridge via a tube may be used. When ink droplets are ejected from the selected ejection port 17, an electrical signal is applied to the contact 15 in order to give ejection energy to the ink droplet generator.

  2 and 3 show an example of the liquid discharge head according to the present invention. FIG. 2 is a cross-sectional view of the liquid discharge head, and FIG. 3 is a side view of the liquid discharge head. The liquid discharge head shown in FIGS. 2 and 3 includes a silicon substrate 21 and a droplet generation structure 23 formed on the surface 21a of the silicon substrate. The droplet generation structure 23 has a droplet generator (not shown) such as a thermal droplet generator that includes a foaming chamber for energizing a liquid to foam and a discharge port for discharging the liquid. As shown in FIG. 3, the liquid ejection head includes a vertical extension along the reference axis L in the longitudinal direction. The discharge ports are arranged vertically in accordance with the reference axis L. The droplet generation structure 23 includes a thin film stack 25 and a discharge port forming layer 27. The thin film stack 25 mounts heater resistors that heat the liquid, and related electrical circuit configurations such as drive and addressing circuits. The thin film stack 25 can be formed by, for example, integrated circuit thin film technology. The discharge port forming layer 27 includes a foaming chamber, a flow path, and a discharge port. A supply port 29 for supplying a liquid to the droplet generation structure 23 is formed in the silicon substrate 21. The liquid is supplied to the droplet generation structure 23 from the storage portion of the cartridge body 11 through the supply port 29, for example. The supply port 29 extends along the reference axis L. The droplet generator is arranged on one side or both sides of the elongated supply port 29.

  Hereinafter, although the embodiment of the manufacturing method of the substrate for liquid discharge heads concerning the present invention and the manufacturing method of the print cartridge provided with the substrate for liquid discharge heads is shown, the present invention is not limited to these.

(First embodiment)
In the present embodiment, a liquid discharge head substrate is manufactured by the method shown in FIG.

  First, as shown in FIG. 4A, a droplet generation structure 23 including a thin film stack 25 and a discharge port formation layer 27 is formed on a surface which is a <100> plane of a silicon substrate 21 having a thickness STH. . The droplet generation structure 23 can be formed by, for example, a thin film integrated circuit process and a photo process etching technique.

  Next, as shown in FIG. 4B, an etching mask layer 41 having an opening width W2 is formed on the back surface of the silicon substrate 21 in order to expose the back side portion of the silicon substrate 21 to be etched later.

  Next, as shown in FIG. 4C, vertical dry etching is performed on the back surface of the silicon substrate 21 through the etching mask layer 41 to form a hole 28 having an opening width W2 and a depth DD. By forming the hole 28 by vertical dry etching, the supply port can be formed earlier than when the supply port is formed only by crystal anisotropic etching. Examples of the vertical dry etching method include reactive ion etching. DD is preferably 10 to 90% of STH from the viewpoint that the subsequent crystal anisotropic etching can be efficiently performed.

  Next, as shown in FIG. 4D, crystal anisotropic etching is performed on the silicon substrate 21 through the etching mask layer 41 to expand the hole 28 to form a supply port. As shown in FIG. 4D, a <111> surface 26 having an angle of 54.7 degrees is formed in the supply port. Examples of the method of crystal anisotropic etching include a method of performing etching using a wet etching solution. Examples of the wet etching solution include a TMAH (tetramethyl ammonium hydroxide) solution and a KOH (potassium hydroxide) solution. The opening width W2 satisfies the following expression in relation to the thickness STH of the silicon substrate 21, the depth DD of the hole 28, and the opening width W1 of the supply port on the surface of the silicon substrate 21.

W2≈tan (54.7 °) × (STH−DD) + W1
54.7 ° is an angle between the <100> plane and the <111> plane. W2 and DD can be appropriately selected so as to achieve a desired W1.

  In the present embodiment, the supply port reaches the surface of the silicon substrate 21, but the supply port may be formed until just before reaching the surface. In this case, the supply port can reach the surface of the silicon substrate 21 by isotropic etching described later. For example, the supply port can be formed from the surface of the silicon substrate 21 to a position of 1% or more and 10% or less of STH.

Next, as shown in FIG. 4E, isotropic etching is performed on the silicon substrate 21 via the etching mask layer 41 to expand the supply port. At this time, the corner shape of the supply port formed by the crystal anisotropic etching is removed to form a curved shape, that is, a round shape. The curved shape is preferably an R shape. Here, the corner of the supply port refers to a portion in which a square shape in the supply port is formed, for example, a corner portion of the opening of the supply port, such as a silicon substrate in the supply port as shown in FIG. And a recessed corner portion at the center in the thickness direction. Examples of the isotropic etching method include wet etching or dry etching. As the wet etching, there is a method in which the entire wall is isotropically etched in a short time using an etching solution capable of isotropic etching such as a hydrofluoric acid solution. Examples of dry etching include a method in which chemical dry etching is performed for a long time using an assist gas in which the mixing ratio of O ₂ (oxygen) and Cl ₄ (carbon tetrachloride) is adjusted. At this time, the opening width W1 of the supply port on the surface side of the silicon substrate 21 widens by several tens of μm to become W0. In order to realize W0 which is the target value of the opening width of the supply port, W2 and DD can be set as appropriate.

  When the R shape is formed at the corner of the opening of the supply port, the radius of curvature of the R shape is preferably 5 μm or more and 20 μm or less, and more preferably 7 μm or more and 15 μm or less. When the radius of curvature is 5 μm or more, the concentrated stress can be sufficiently dispersed. Further, when the radius of curvature is 20 μm or less, it is easy to manage the accuracy of the shape of the supply port by isotropic etching, such as the prescription of the etching solution and the control of the process. The radius of curvature is a value measured by performing image processing on an image obtained with a microscope or the like.

  Next, as shown in FIG. 4F, the etching mask layer 41 is removed.

  Through the above-described steps, the liquid discharge head substrate according to the present embodiment is obtained.

(Second embodiment)
In the present embodiment, a liquid discharge head substrate is manufactured by the method shown in FIG.

  First, as shown in FIG. 5A, an etching mask layer 53 is formed on the back surface of the silicon substrate 50. For example, silicon nitride films are formed on the front and back surfaces of the silicon substrate 50 by LPCVD (Low Pressure Chemical Vapor Deposition), respectively. A photoresist mask is formed on the silicon nitride film on the back surface of the silicon substrate 50 by a photolithography process, and reactive ion etching is performed through the mask to expose the silicon substrate 50. Thereafter, the photoresist mask is removed to form an etching mask layer 53 having an opening 54. Further, the silicon nitride film on the surface of the silicon substrate 50 is removed by reactive ion etching.

  Next, the sacrificial layer 51 is formed. For example, a Cu thin film is formed by a vacuum deposition method, and a photoresist mask is formed on the Cu thin film by a photolithography process. After etching the Cu thin film through the mask, the photoresist mask is peeled off to form a sacrificial layer 51. FIG. 6 shows a pattern of the sacrificial layer 51 viewed from the upper surface of the silicon substrate 50. In this embodiment, the sacrificial layer 51 has a square shape with one side d1. Here, when the opening length D of the opening 54 penetrates the silicon substrate 50 by crystal anisotropic etching as shown by a dotted line, δ shown in the cross-sectional view of FIG. It is preferable to make it smaller than that from the viewpoint of performing etching within the range of the sacrificial layer 51 in the crystal anisotropic etching. In addition, when the sacrificial layer 51 is formed of copper, the sacrificial layer 51 is formed 20 to 40 μm inside compared to the case where the sacrificial layer 51 is formed of aluminum, and a target supply port width after the isotropic etching described later is performed. It is preferable that The sacrificial layer 51 is preferably formed of a material having an etching rate higher than that of the silicon substrate 50.

  Next, as shown in FIG. 5B, a passivation layer 52 having etching resistance is formed so as to cover the sacrificial layer 51. For example, a silicon nitride film can be used as the passivation layer 52.

  Next, as shown in FIG. 5C, a trapezoidal groove surrounded by the <111> face 26 is formed by crystal anisotropic etching. Crystal anisotropic etching can be performed using, for example, a potassium hydroxide (KOH) aqueous solution.

  Next, as shown in FIG. 5D, after the sacrificial layer 51 is removed, the silicon substrate 50 under the sacrificial layer 51 is crystal anisotropically etched to form a membrane 57 of the passivation layer 52. As a result, a supply port having a shape with a narrow width toward the central portion in the thickness direction of the silicon substrate 50 and an inner surface of the <111> surface 26 is obtained. The sacrificial layer 51 can be removed by isotropic etching. Isotropic etching can be performed, for example, with a ferric chloride aqueous solution. Crystal anisotropic etching can be performed using a potassium hydroxide (KOH) aqueous solution in the same manner as described above. In this embodiment, the sacrificial layer 51 is removed using an etching solution different from the etching solution used in the crystal anisotropic etching. However, from the viewpoint of operability, the same etching solution as the etching solution used in the crystal anisotropic etching is used. The sacrificial layer 51 may be removed using In this case, the sacrificial layer 51 is removed by etching, but crystal anisotropic etching is not performed unlike the silicon substrate.

  Next, as shown in FIG. 5E, isotropic etching is performed on the silicon substrate 50 through the etching mask layer 53 to expand the supply port, as in the first embodiment. At this time, as shown in FIG. 7, the corner of the supply port formed by crystal anisotropic etching, that is, the corner of the opening of the supply port, and the protrusion in the central portion in the thickness direction of the silicon substrate 50 in the supply port The corner shape of the corner is removed and becomes a curved shape.

  A portion having the smallest opening area in a cross section perpendicular to the thickness direction of the silicon substrate 50 in the supply port (the direction in which the supply port extends) is formed by the apex of the protruding corner portion of the central portion in the thickness direction of the silicon substrate 50 in the supply port. Is formed. That is, the opening area in the cross section orthogonal to the thickness direction of the silicon substrate 50 at the supply port (the direction in which the supply port extends) continuously increases from the corner portion toward the front surface and the back surface of the silicon substrate 50.

Next, as shown in FIG. 5F, the membrane 57 of the passivation layer 52 is removed. The membrane 57 of the passivation layer 52 can be removed, for example, by performing reactive ion etching from the back surface of the silicon substrate 50 using CF ₄ gas.

  Through the above-described steps, the liquid discharge head substrate according to the present embodiment is obtained. In the manufacturing method according to the present embodiment, since the supply port is formed using the sacrificial layer and the passivation layer, the supply port can be formed with high accuracy.

(Third embodiment)
In the present embodiment, a print cartridge is manufactured by the method shown in FIG. 9A to 9K are cross-sectional views taken along line AA ′ in FIG.

First, as shown in FIG. 9A, a silicon substrate 101 is prepared. A plurality of energy generating elements 103 such as heating resistors are arranged on the surface of the silicon substrate 101. Note that wiring of the energy generating element 103 and a semiconductor element for driving the energy generating element 103 are not shown. A SiO ₂ film 106 is formed on the back surface of the silicon substrate 101. A sacrificial layer 102 is formed on the surface of the silicon substrate 101 in order to accurately form the opening 105 of the supply port. The sacrificial layer 102 can be etched with an etchant of the silicon substrate 101 such as an alkaline solution. The sacrificial layer 102 can be formed of, for example, poly Si, aluminum having a high etching rate, aluminum Si, aluminum copper, aluminum Si copper, or the like.

  In addition, a passivation layer 104 is formed so as to cover the sacrificial layer 102. As the passivation layer 104, a material having etching resistance can be used because the etching does not proceed with the etchant after the sacrificial layer 102 is etched in crystal anisotropic etching in a later step. As a material for the passivation layer 104, for example, silicon oxide, silicon nitride, or the like can be used. The passivation layer 104 may be disposed on the back side of the energy generating element 103 and used as a heat storage layer. Alternatively, the passivation layer 104 may be disposed on the energy generation element 103 and used as a protective film.

  Next, as shown in FIG. 9B, an etching mask layer 108 is formed on the back surface of the silicon substrate 101. The etching mask layer 108 can be formed by the following method, for example. A polyether amide resin is applied and baked to form a layer to be the etching mask layer 108. In order to pattern the layer, a positive resist is applied onto the layer by spin coating, exposed and developed, the layer is patterned by dry etching or the like, and the positive resist is peeled off. Thus, an etching mask layer 108 having an opening corresponding to the sacrificial layer 102 is formed. This opening becomes an etching start surface in later crystal anisotropic etching and isotropic etching.

  Thereafter, the intermediate layer 107 is formed. The intermediate layer 107 can be formed by, for example, the following method. For example, a polyether amide resin is applied to the surface of the passivation layer 104 and cured. Then, a positive resist is applied by spin coating or the like, exposed, and developed. The intermediate layer 107 can be formed by patterning the polyetheramide resin by dry etching or the like and removing the positive resist.

  Next, as shown in FIG. 9C, a positive resist is applied to the surface side of the silicon substrate 101 and patterned to form a mold material 110 that serves as a liquid flow path mold.

  Next, as shown in FIG. 9D, the flow path forming member 112 is formed on the mold 110 by spin coating or the like. Further thereon, a water repellent film 113 is formed by laminating a dry film or the like. The liquid discharge port 114 can be formed by exposure and development using ultraviolet light or deep UV light.

  Next, as shown in FIG. 9E, the surface and side surfaces of the silicon substrate 101 on which the flow path forming member 112 and the like are formed are covered with a protective material 115 by spin coating or the like.

  Next, as shown in FIG. 9F, the opening of the etching mask layer 108 is irradiated with laser light from the back side of the silicon substrate 101 to form a leading hole 220 that is a recess. The formation of the leading hole 220 in this manner is preferable because the supply port can be formed earlier than when the supply port is formed only by crystal anisotropic etching. The depth of the leading hole 220 is preferably 10 to 90% with respect to the thickness of the silicon substrate 101. The number of leading holes 220 is not particularly limited.

  Next, as shown in FIG. 9G, crystal anisotropic etching is performed from the back surface of the silicon substrate using an etching solution such as a TMAH solution through the etching mask layer 108. In this etching, first, etching proceeds from the tip of the leading hole 220, and a hole with a <111> plane is formed at 54.7 ° with respect to the back surface of the silicon substrate. When the etching further proceeds, as shown in FIG. 9H, the etching proceeds from the <100> surface 107 at the tip of the leading hole 220, and is formed at 54.7 ° with respect to the back surface of the silicon substrate. The <111> plane 26 reaches the sacrificial layer 102. The sacrificial layer 102 is isotropically etched with an etching solution, the upper end of the supply port corresponds to the shape of the sacrificial layer 102, and the cross-sectional shape is formed in a barrel shape by the <111> plane.

  Next, as shown in FIG. 9 (i), the etching solution is replaced with an etching solution capable of isotropic etching such as a hydrofluoric acid solution, isotropic etching is performed for a short time, and the supply port 109 is expanded. Let As a result, the corners of the opening of the supply port 109 and the corners in the vicinity of the central portion in the thickness direction of the silicon substrate 101 in the supply port are removed to form a curved shape.

  Next, as shown in FIG. 9J, a part of the passivation layer 104 is removed by dry etching or the like.

  Next, as shown in FIG. 9K, the etching mask layer 108 and the protective material 115 are removed. Further, the flow path is formed by eluting the mold 110 from the discharge port 114 and the supply port 109.

  Next, the silicon substrate 101 is cut and separated by a dicing saw or the like to form a chip, and electrical bonding for driving the energy generating element 103 is performed. Thereafter, the silicon substrate 101 formed into a chip is incorporated into the cartridge main body 11 for supplying liquid to obtain a print cartridge.

  In this embodiment, since the corner of the opening of the supply port 109 is curved, the stress concentration at the corner of the opening of the supply port 109 can be dispersed by the deformation of the silicon substrate 101 in the manufacturing process. In addition, the substrate can be prevented from being damaged due to the occurrence of cracks. In addition, since the corner of the wide portion of the central portion in the thickness direction of the silicon substrate 101 in the supply port is also curved, air is trapped at the corner when the liquid is filled in the flow path, and bubble residue is generated. Can be suppressed, and the flow of the liquid becomes good. Thereby, the liquid can be normally discharged from the discharge port.

  Examples of the present invention will be described below, but the present invention is not limited to these.

(Example 1)
In this example, a liquid discharge head substrate was fabricated by the method shown in FIG.

  First, as shown in FIG. 4A, the droplet generation structure 23 was formed on the surface which is the <100> plane of the silicon substrate 21 having the thickness STH. The droplet generation structure 23 includes a heater resistor that heats a liquid, a thin film stack 25 that implements related electric circuit configurations such as a drive circuit and an addressing circuit, and a discharge chamber that forms a foaming chamber, a flow path, and a discharge port 17. And an outlet forming layer 27. The droplet generation structure 23 was formed by a thin film integrated circuit process and a photo process.

  Next, as shown in FIG. 4B, an etching mask layer 41 having an opening width W <b> 2 was formed on the back surface of the silicon substrate 21.

  Next, as shown in FIG. 4C, vertical dry etching (reactive ion etching) was performed on the silicon substrate 21 via the etching mask layer 41 to form a hole with a depth DD. DD was 30% of STH.

  Next, as shown in FIG. 4D, the silicon substrate 21 is subjected to crystal anisotropic etching using a TMAH solution through an etching mask layer 41 to expand the hole, and to supply the supply port. Formed. At this time, as shown in FIG. 4D, a <111> surface having an angle of 54.7 degrees was formed in the supply port.

  Next, as shown in FIG. 4E, isotropic etching was performed on the silicon substrate 21 using a hydrofluoric acid solution through the etching mask layer 41 to expand the supply port. At this time, the corners of the corner of the opening of the supply port and the corner near the central portion in the thickness direction of the silicon substrate 21 in the supply port were removed to form a curved shape. The radius of curvature of the corner of the opening of the supply port was 10 μm.

  Next, as shown in FIG. 4F, the etching mask layer 41 was removed.

  Through the above steps, a liquid discharge head substrate was completed. Since the corner of the opening of the supply port is curved, the liquid discharge head substrate showed high mechanical strength. Further, since the liquid discharge head substrate has a curved corner near the center in the thickness direction of the silicon substrate 21 in the supply port, the liquid flow in the supply port is good when the liquid discharge head is manufactured. Yes, the liquid could be discharged well from the discharge port.

(Example 2)
In this example, a liquid discharge head substrate was fabricated by the method shown in FIG.

First, as shown in FIG. 5A, a silicon nitride film having a thickness of 500 nm serving as an etching mask layer 53 is formed on the front and back surfaces of a silicon substrate 50 having a thickness of 525 μm and a crystal plane of <100>. Each was formed by LPCVD. A photoresist mask is formed on the silicon nitride film on the back surface of the silicon substrate 50 by a photolithography process, and reactive ion etching using CF ₄ gas is performed through the mask to expose the silicon substrate 50. It was. Thereafter, an etching mask layer 53 having an opening 54 was formed by removing the photoresist mask. Further, the silicon nitride film on the surface of the silicon substrate 50 was removed by reactive ion etching using CF ₄ gas.

  Next, a Cu thin film having a thickness of 3 μm to be the sacrificial layer 51 was formed by a vacuum deposition method. A photoresist mask was formed on the Cu thin film by a photolithography process, and the Cu thin film was etched with 20 mass% ferric chloride aqueous solution through the mask. Thereafter, the photoresist mask was removed to form a sacrificial layer 51. As shown in FIG. 6, the sacrificial layer 51 is a square with one side d1, and the opening width D of the opening 54 is set so that δ shown in FIG. 6B is smaller than d1.

  Next, as shown in FIG. 5B, a silicon nitride film having a thickness of 500 nm as the passivation layer 52 was formed so as to cover the sacrificial layer 51.

  Next, as shown in FIG. 5C, crystal anisotropic etching is performed on the silicon substrate 50 with an aqueous potassium hydroxide (KOH) solution through the etching mask layer 53, and a <111> crystal plane is obtained. A trapezoidal groove surrounded by is formed.

  Next, as shown in FIG. 5D, the sacrificial layer 51 was exposed and removed by isotropic etching with a 20 mass% aqueous ferric chloride solution. Thereafter, crystal anisotropic etching was performed again on the silicon substrate 50 below the sacrificial layer 51 with an aqueous KOH solution to form a <111> crystal plane, and a supply port was obtained. In addition, a membrane 57 of the passivation layer 52 was formed.

  Next, as shown in FIG. 5E, isotropic etching was performed on the silicon substrate 50 using a hydrofluoric acid solution through the etching mask layer 53 to expand the supply port. At this time, the corner shape of the corner of the opening of the supply port and the corner near the central portion in the supply port was removed to form a curved shape. The radius of curvature of the corner of the opening of the supply port was 10 μm.

Next, as shown in FIG. 5 (f), reactive ion etching is performed from the back surface of the silicon substrate 50 through the etching mask layer 53 using CF ₄ gas to remove the membrane 57 of the passivation layer 52. did.

  Through the above steps, a liquid discharge head substrate was completed. In the manufacturing method according to this example, the supply port was formed using the sacrificial layer and the passivation layer, and thus the supply port could be formed with high accuracy. Since the corner of the opening of the supply port is curved, the liquid discharge head substrate showed high mechanical strength. Further, since the liquid discharge head substrate has a curved corner near the center in the thickness direction of the silicon substrate 21 in the supply port, the liquid flow in the supply port is good when the liquid discharge head is manufactured. Yes, the liquid could be discharged well from the discharge port.

(Example 3)
In this example, a print cartridge was produced by the method shown in FIG.

First, as shown in FIG. 9A, a silicon substrate 101 was prepared. On the surface of the silicon substrate 101, a plurality of energy generating elements 103 as heating resistors are arranged. Note that wiring of the energy generating element 103 and a semiconductor element for driving the energy generating element 103 are not shown. A SiO ₂ film 106 is formed on the back surface of the silicon substrate 101. A sacrificial layer 102 made of aluminum was formed on the surface of the silicon substrate 101. A passivation layer 104 was formed so as to cover the sacrificial layer 102.

  Next, as shown in FIG. 9B, an etching mask layer 108 was formed on the back surface of the silicon substrate 101. Specifically, a polyether amide resin was applied and baked to form a layer to be the etching mask layer 108. A positive resist was applied onto the layer by spin coating, exposed and developed, the layer was patterned by dry etching, and the positive resist was peeled off. Thus, an etching mask layer 108 having an opening corresponding to the sacrificial layer 102 was formed.

  Thereafter, a polyetheramide resin was applied to the surface of the passivation layer 104 and cured. A positive resist was applied by spin coating, exposed, and developed. The polyether amide resin was patterned by dry etching, and the positive resist was removed. Thereby, the intermediate layer 107 was formed.

  Next, as shown in FIG. 9 (c), a positive resist was applied to the surface side of the silicon substrate 101 and patterned to form a mold material 110 serving as a liquid flow path mold.

  Next, as shown in FIG. 9D, the flow path forming member 112 was formed on the mold 110 by spin coating. Further thereon, a water repellent film 113 was formed by laminating a dry film. The liquid discharge port 114 was formed by exposure and development with deep UV light.

  Next, as shown in FIG. 9E, the surface and side surfaces of the silicon substrate 101 on which the flow path forming member 112 and the like were formed were covered with a protective material 115 by spin coating.

  Next, as shown in FIG. 9 (f), a leading hole 220 that is a non-penetrating recess was formed by laser processing from the back surface side of the silicon substrate 101. The depth of the leading hole 220 was 70% with respect to the thickness of the silicon substrate 101.

  Next, as shown in FIG. 9G, crystal anisotropic etching was performed from the back surface of the silicon substrate using the TMAH solution through the etching mask layer 108. In this etching, first, the etching progressed from the tip of the leading hole 220. When the etching further progressed, as shown in FIG. 9H, the etching progressed from the <100> surface 107 at the tip of the leading hole 220, and the <111> surface 26 reached the sacrificial layer 102. The sacrificial layer 102 was isotropically etched with an etching solution, and the upper end of the supply port corresponded to the shape of the sacrificial layer 102, and the cross-sectional shape was formed into a barrel shape by the <111> surface 26.

  Next, as shown in FIG. 9 (i), isotropic etching was performed for a short time with a fluorinated nitric acid solution to expand the supply port 109. At this time, the corners of the opening portion of the supply port 109 and the corner portion in the vicinity of the central portion in the thickness direction of the silicon substrate 101 in the supply port were removed to form a curved shape. The radius of curvature of the corner of the opening of the supply port 109 was 10 μm.

  Next, as shown in FIG. 9J, a part of the passivation layer 104 was removed by dry etching.

  Next, as shown in FIG. 9K, the etching mask layer 108 and the protective material 115 were removed. Further, the flow path was formed by eluting the mold material 110 from the discharge port 114 and the supply port 109.

  Next, the silicon substrate 101 was cut and separated by a dicing saw to form a chip, and electrical bonding for driving the energy generating element 103 was performed. Thereafter, the silicon substrate 101 formed into a chip was incorporated into the cartridge main body 11 for supplying liquid to complete the print cartridge.

  Since the liquid discharge head substrate in this example has a curved corner at the opening of the supply port, it showed high mechanical strength and could prevent the substrate from being damaged during the manufacturing process. Further, since the liquid discharge head substrate has a curved corner near the center in the thickness direction of the silicon substrate in the supply port, the print cartridge has a good flow of liquid in the supply port. Was successfully discharged.

DESCRIPTION OF SYMBOLS 10 Print cartridge 11 Cartridge body 13 Print head 15 Electrical contact 17 Discharge port 21 Silicon substrate 23 Droplet generating structure 24 Corner 25 near the center of the silicon substrate in the thickness direction Thin film stack 26 <111> surface 27 Discharge port forming layer 28 Hole 29 supply port 41 etching mask layer 50 silicon substrate 51 sacrificial layer 52 passivation layer 53 etching mask layer 54 opening 57 membrane 101 silicon substrate 102 sacrificial layer 103 energy generating element 104 passivation layer 105 supply port opening 106 SiO _Two films 107 <100> surface 108 Etching mask layer 109 Supply port 112 Flow path forming member 113 Water repellent film 114 Discharge port 115 Protective film 116 Corner portion 117 of supply port opening crack 220 Leading hole

Claims (9)

(A) forming an etching mask layer on one surface of the silicon substrate;
(B) performing crystal anisotropic etching on the silicon substrate through the etching mask layer, and forming a liquid supply port until reaching or just before reaching the other surface of the silicon substrate;
(C) performing isotropic etching through the etching mask layer, further expanding the supply port, and bending the corner of the supply port;
Of manufacturing a substrate for a liquid discharge head, comprising: (A) forming a sacrificial layer on one surface of the silicon substrate;
(B) forming a passivation layer having etching resistance so as to cover the sacrificial layer;
(C) forming an etching mask layer having an opening corresponding to the sacrificial layer on the other surface of the silicon substrate;
(D) performing crystal anisotropic etching on the silicon substrate via the etching mask layer to form a liquid supply port;
(E) removing the sacrificial layer;
(F) performing isotropic etching through the etching mask layer, further expanding the supply port, and bending the corner of the supply port;
(G) removing a part of the passivation layer and opening the supply port on one side of the silicon substrate;
Of manufacturing a substrate for a liquid discharge head, comprising:   3. The method of forming a recess on the other surface of the silicon substrate by irradiating a laser beam to the opening of the etching mask layer between the step (c) and the step (d). A manufacturing method of a substrate for liquid discharge heads given in the above.   4. The method for manufacturing a substrate for a liquid discharge head according to claim 2, wherein in the step (d), a supply port having a narrow width is formed toward a central portion in the thickness direction of the silicon substrate by crystal anisotropic etching.   5. The liquid discharge head substrate according to claim 2, wherein crystal anisotropic etching is performed with an etchant in the step (d), and the sacrificial layer is removed with the etchant in the step (e). Production method.   The method for manufacturing a substrate for a liquid discharge head according to claim 1, wherein the isotropic etching is wet etching using a hydrofluoric acid solution.   The method for manufacturing a substrate for a liquid discharge head according to claim 1, wherein the isotropic etching is dry etching.   The corner of the supply port is a corner of the opening of the supply port, and the curvature radius of the curved corner is 5 μm or more and 20 μm or less. Manufacturing method for a liquid discharge head substrate.   The method for manufacturing a substrate for a liquid discharge head according to claim 1, wherein the surface of the silicon substrate is a <100> plane.

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