JP2020049685A - Substrate for liquid discharge head, manufacturing method of the same, liquid discharge head, and liquid discharge device - Google Patents

Abstract

To provide a technology that enables an upper layer wiring layer formed by a thin film to be stably and electrically connected to a lower layer wiring layer.SOLUTION: A substrate for a liquid discharge head includes: a first wiring layer 102 formed on a substrate; a second wiring layer 216 formed on an upper layer of the first wiring layer through an insulation film 104; and a plug 112 which is provided within a hole part 106 formed in the insulation film so as to reach the first wiring layer and may electrically connect the first wiring layer with the second wiring layer. The second wiring layer is formed within the hole part and on the insulation film, and the plug is formed on the second wiring layer at the hole part.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a substrate for a liquid ejection head including an ejection energy generating element for ejecting liquid, a method for manufacturing the same, a liquid ejection head, and a liquid ejection device.

  2. Description of the Related Art In a liquid ejection head that ejects liquid using a heating resistor as an ejection energy generating element, a heating resistor and a drive circuit that drives the heating resistor are formed on a semiconductor substrate. In Patent Document 1, in order to ensure the reliability of circuit driving while arranging heating resistors at high density on a substrate, a MOS transistor constituting a driving circuit is electrically connected to a wiring layer by a metal plug using tungsten. Is disclosed.

  When forming the metal plug, first, an interlayer insulating film is formed on a semiconductor substrate on which a lower wiring layer such as a drive circuit is formed, and a via hole reaching the lower wiring layer is formed in the interlayer insulating film. Next, a contact metal and a barrier metal are sequentially laminated to form a metal film, and then a metal plug material is deposited so as to fill the via hole. Then, the metal plug material outside the via hole is removed together with the metal film by an etch back method or a CMP (Chemical Mechanical Polish) method. An upper wiring layer such as a heating resistor element is formed on the metal plug and the interlayer insulating film thus formed, and the upper wiring layer and the lower wiring layer are electrically connected via the metal plug.

JP 2005-178364 A

  In a general etch-back method or CMP method, an etching rate or a polishing rate differs between an interlayer insulating film and a metal plug material. Therefore, the upper surface of the interlayer insulating film and the upper surface of the metal plug are not flush with each other, and the metal plug portion has a concave shape. The upper wiring layer formed on the metal plug and the interlayer insulating film is usually formed by patterning a metal film formed by sputtering.

  Therefore, when the metal film for forming the upper wiring layer is formed with a film thickness sufficiently large with respect to the concave amount of the concave portion in the metal plug, the metal film is surely embedded in the concave portion. The problem is hardly caused in the electrical connection between the metal plug and the upper wiring layer. However, when the metal film for forming the upper wiring layer is formed as a thin film having a thickness equal to or less than the recess amount, a problem may occur in the electrical connection between the metal plug and the upper wiring layer. .

  That is, since the sputtering has low coverage of the step portion, the formed metal film is liable to cause disconnection of the wiring or disconnection due to migration in the recessed step portion. For this reason, the connection between the metal plug and the upper wiring layer becomes unstable, and there is a possibility that the upper wiring layer cannot be electrically stably connected to the lower wiring layer.

  The present invention has been made in view of the above problems, and has as its object to provide a technique capable of electrically stably connecting an upper wiring layer of a thin film to a lower wiring layer.

  In order to achieve the above object, the present invention provides a semiconductor device comprising: a first wiring layer formed on a substrate; a second wiring layer formed on the first wiring layer via an insulating film; A liquid ejection head substrate provided in a hole formed so as to reach the first wiring layer and comprising a plug capable of electrically connecting the first wiring layer and the second wiring layer, The second wiring layer is formed inside the hole and on the insulating film, and the plug is formed on the second wiring layer in the hole.

  According to the present invention, the upper wiring layer of the thin film can be electrically and stably connected to the lower wiring layer.

FIG. 2 is a schematic configuration diagram of a recording device. FIG. 2 is a schematic configuration diagram of a recording head unit and a recording head. FIG. 9 is a diagram illustrating a part of the manufacturing process of the printhead substrate of the comparative example. FIG. 4 is a view showing a part of the manufacturing process of the recording head substrate according to the present invention. FIG. 3 is a diagram illustrating a heating resistor element and a temperature detection element in the vicinity of an ejection port in a print head. VI-VI sectional drawing of FIG.

  Hereinafter, an example of a substrate for a liquid ejection head, a method for manufacturing the same, a liquid ejection head, and a liquid ejection device according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, an ink jet recording apparatus (hereinafter, appropriately referred to as a “recording apparatus”) will be described as an example of a liquid ejection apparatus that ejects liquid from a liquid ejection head.

  FIG. 1 is a schematic configuration diagram of a recording apparatus which is a liquid ejection apparatus according to the present invention. The recording apparatus 10 shown in FIG. 1 discharges ink from a recording head unit 16 that scans a recording medium M to be conveyed in a direction intersecting (in this embodiment, orthogonal to) a conveying direction to perform recording. , A serial scan type inkjet recording apparatus.

  The recording apparatus 10 includes a carriage 14 movably provided along a guide shaft 12 extending in a scanning direction that intersects the conveyance direction of the recording medium M, and a recording head unit 16 detachably mounted on the carriage 14. And Further, a platen 18 for supporting the recording medium M conveyed in the conveying direction by a conveying roller (not shown), a feeding unit 20 for feeding the recording medium M to the conveying roller, and the recorded recording medium M being ejected. And a discharge unit 22. Further, a recovery unit 24 for maintaining and recovering the ejection performance of the ink from the ejection port 46 (described later) of the recording head unit 16 is provided on one end side of the moving area of the carriage 14 in the scanning direction. Have. The overall operation of the recording device 10 is controlled by a control unit (not shown).

  More specifically, the carriage 14 is connected to a belt (not shown) driven by a motor (not shown), and reciprocates in the scanning direction along the guide shaft 12 by driving the belt. Therefore, the recording head unit 16 is configured to be able to reciprocate in the scanning direction via the carriage 14. A plurality of recording head units 16 are mounted on the carriage 14, and different types of ink are ejected from each of the recording head units 16. That is, the recording apparatus 10 intermittently repeats a transport operation of transporting the recording medium M in the transport direction and a recording operation of ejecting ink while moving the recording head unit 16 in the scanning direction, and performs a desired operation on the recording medium. Will be recorded.

  The recovery unit 24 includes, for example, a cap (not shown) that protects an ejection port surface (one surface 26 a of the recording head 26 described later) in which the ejection port 46 for ejecting ink is formed in the recording head unit 16. . In addition, the recovery unit 24 includes, for example, a wiper (not shown) for wiping a predetermined area including each of the discharge ports 46.

  FIG. 2A is a schematic configuration diagram of the recording head unit 16, and FIG. 2B is a schematic configuration diagram showing a part of the recording head 26 cut away. The recording head unit 16 is a cartridge-type unit in which the recording head 26 and the ink tank 28 are integrated. The recording head unit 16 is mounted on the carriage 14 such that the ejection port 46 faces the platen 18.

  The recording head unit 16 is configured to be attachable to and detachable from the carriage 14. A tape member 30 for TAB (Tape Automated Bonding), which is connected to the recording head 26 and has a terminal for supplying power to elements provided on the recording head 26, is attached to the recording head unit 16. In the recording head unit 16 mounted on the carriage 14, electric power is supplied to the recording head 26 from a contact 32 provided on the tape member 30.

  The recording head 26 has a flow path forming member 36 formed on one surface 34 a of a recording head substrate 34. A plurality of pressure chambers 38 capable of storing ink therein are formed in the flow path forming member 36. A discharge port 46 for discharging ink to the outside is formed in the pressure chamber 38. The surface of the pressure chamber 38 facing the ejection port 46 is constituted by the recording head substrate 34, and a heating resistor element 48 is provided at a position facing the ejection port 46 on the recording head substrate 34.

  The recording head substrate 34 has an ink supply port 40 penetrating from one surface 34a to the other surface 34b. A common liquid chamber 42 is formed in the flow path forming member 36 so as to communicate with the ink supply port 40. The common liquid chamber 42 communicates with each pressure chamber 38 via an ink flow path 44 in the flow path forming member 36. The flow path forming member 36 is composed of, for example, a plurality of members.

  When ink is supplied from the ink tank 28 to the recording head 26, the ink is supplied to the common liquid chamber 42 through the ink supply port 40 of the recording head substrate 34. The ink supplied to the common liquid chamber 42 is supplied to each pressure chamber 38 through the ink flow path 44. At this time, the ink in the common liquid chamber 42 is supplied to the ink flow path 44 and the pressure chamber 38 by capillary action, and a meniscus is formed at the discharge port 46, so that the liquid level of the ink is stably held.

  The recording head substrate 34 includes a heating resistor 48 at a position corresponding to each pressure chamber 38. When the ink is ejected from the ejection port 46, the heating resistor element 48 is energized. This energization causes the heating resistor element to generate heat, thereby heating the ink in the pressure chamber 38, and utilizing the pressure change caused by the growth and shrinkage (cavitation phenomenon) of bubbles due to the film boiling of the heated ink, to cause the ink to flow from the ejection port 46. Will be discharged.

  Here, a recording head substrate 134 as a comparative example of the recording head substrate 34 will be described with reference to FIG. The recording head substrate 134 is manufactured by, for example, a known technique disclosed in Patent Document 1. FIGS. 3A to 3G are diagrams illustrating a process of forming a metal plug and a process of forming an upper wiring layer of a printhead substrate 134 as a comparative example.

  In a recording head substrate 134 as a comparative example, an interlayer insulating film 104 is formed on a substrate 100 such as silicon on which a lower wiring layer 102 is formed. In the following description, a known technique can be used for various processes such as film formation, and a detailed description thereof will be appropriately omitted. The surface 104a of the formed interlayer insulating film 104 is polished flat by a CMP method (see FIG. 3A).

  Then, a photosensitive resist is patterned by a photolithography technique, and a via hole 106 reaching the lower wiring layer 102 is formed in the interlayer insulating film 104 (see FIG. 3B). After that, a metal film 108 such as a contact metal or a barrier metal such as a diffusion prevention film is formed on the surface 104a and the via hole 106 (see FIG. 3C).

  Next, the metal plug material 110 is formed by a CVD (Chemical vapor deposition) method or the like so as to have a thickness enough to fill the via hole 106 (see FIG. 3D). Then, the metal plug material 110 on the metal film 108 is polished and removed together with the metal film 108 such as a barrier metal by the CMP method while leaving the metal plug material 110 in the via hole 106 (see FIG. 3E). . As a method of removing the metal plug material 110, an etch-back method may be used.

  As a result, the metal plug 112 is formed in the via hole 106. Here, in the CMP method and the etch-back method, the polishing rate and the etching rate are different between the interlayer insulating film 104 and the metal plug material 110 as described above. Therefore, the formed metal plug 112 is formed so that its surface 112a is recessed from the surface 104a of the interlayer insulating film 104 (see FIG. 3E).

  After that, a metal film 114 such as a barrier metal or a wiring layer is formed on the surface 104a of the interlayer insulating film 104 and the surface 112a of the metal plug 112 (see FIG. 3F). Then, the upper wiring layer 116 is formed by patterning the metal film 114 (see FIG. 3G).

  Thus, in the recording head substrate 134, the upper wiring layer 116 is formed on the surface 112a of the metal plug 112. Thus, the upper wiring layer 116 is electrically connected to the lower wiring layer 102 via the metal plug 112. In the recording head substrate 134, the surface 112a of the metal plug 112 is formed so as to be concave with respect to the surface 104a of the interlayer insulating film 104.

  Normally, upper wiring layer 116 is formed of a metal film that is sufficiently thick with respect to the recessed step formed by metal plug 112 and interlayer insulating film 104. However, although the details will be described later, when a heating resistor element or a temperature detecting element for determining whether or not ink ejection is normally performed is configured as the upper wiring layer 116, the amount of dent in the dent step is equal to that. Alternatively, it is required to be formed with a thin film of less thickness. In the present embodiment, the thin film is, for example, a film having a thickness of 10 nm to 300 nm.

  In this case, since the metal film 114 is formed as a thin film by sputtering with low coverage at the step portion, a nonuniform film may be formed at the step portion generated between the metal plug 112 and the interlayer insulating film 104. Alternatively, there is a possibility that a portion where a film is not formed may occur. That is, in the step portion, in the upper wiring layer 116 formed of the metal film 114, the wiring is disconnected or the disconnection due to the migration easily occurs, and it is difficult to stably secure the electrical connection. Becomes

  Further, there are a plurality of via holes 106 in which the metal plugs 112 are formed. In the metal plugs 112 formed in the plurality of via holes 106, the amount of the recessed step formed by the interlayer insulating film 104 varies. Therefore, when the metal film 114 is formed as a thin film by sputtering under a predetermined condition, there is a possibility that a step portion that is appropriately formed and a step portion that is not formed properly are mixed. .

  Therefore, in the recording head substrate 34 according to the present invention, the upper wiring layer is formed by the bottom surface 112b and the side surface 112c of the metal plug 112 so that the upper wiring layer can be electrically stably connected to the lower wiring layer 102. Connected. That is, in the via hole 106, the metal plug 112 is formed on the upper wiring layer. In other words, the upper wiring layer is located between the inner surface of the via hole 106 (formed by the interlayer insulating film 104 and the lower wiring layer 102) and the metal plug 112.

  Specifically, by forming an upper wiring layer using a metal film formed after the formation of the via hole 106, the metal plug 112 covers the recessed step portion where the coverage is reduced. In the following description, the formation of the metal plug and the upper wiring layer will be mainly described, but a known technique such as Patent Literature 1 can be used as a method for forming other members (layers). Therefore, the description thereof will be appropriately omitted.

  Here, the formation of the metal plug 112 and the upper wiring layer 216 of the recording head substrate 34 will be described with reference to FIG. FIGS. 4A to 4F are diagrams for explaining a process of forming a metal plug and a process of forming an upper wiring layer of the recording head substrate 34 according to the present invention.

  The same processing as that of the recording head substrate 134 is performed on the recording head substrate 34 until the step of forming the via hole 106. That is, first, an interlayer insulating film 104 (insulating film) is formed on the substrate 100 on which the lower wiring layer 102 (first wiring layer) is formed, and the surface 104a is polished flat by the CMP method (FIG. a)). Next, the tourist resist is patterned to form a via hole 106 (hole) reaching the lower wiring layer 102 in the interlayer insulating film 104 (see FIG. 4B).

  Thereafter, a metal film 214 (metal film) serving as both a barrier metal and an upper wiring layer is formed on the surface 104a and the via hole 106 (in the hole) (see FIG. 4C). The metal film 214 is preferably formed by long-throw sputtering in order to improve coverage of the film in the via hole 106. When it is desired to further improve the coverage of the inside of the via hole 106, a collimator may be disposed as an intermediate electrode in order to ensure the straightness of the film-forming particles.

  Note that the metal film 214 (the upper wiring layer 216) may be formed by stacking a plurality of films having different characteristics. The film to be laminated includes a contact metal film for improving electrical connection with the lower wiring layer 102 at the bottom of the via hole 106. In addition, an adhesion improving film for improving the adhesion with the interlayer insulating film 104 is included. Further, it includes a diffusion prevention film having excellent resistance to electro-stress migration. Furthermore, it includes an antireflection film for preventing reflection from a base in a photolithography process.

  The metal film 214 (upper wiring layer 216) may be composed of two layers: a contact metal film and a barrier metal film. For example, the contact metal film using titanium can suppress the contact resistance with the lower wiring layer 102, and the barrier metal film using titanium nitride can improve the diffusion prevention.

  Next, a metal plug material 110 is formed by a CVD method or the like to a thickness enough to fill the via hole 106 (see FIG. 4D). Then, the other metal plug material 110 is removed by an etch back method while leaving the metal film 214 together with the metal plug material 110 in the via hole 106 (see FIG. 4E). As a result, the metal plug 112 is formed on the metal film 214 in the via hole 106, and the metal film 214 is left on the surface 104a of the interlayer insulating film 104. Then, the upper wiring layer 216 (second wiring layer) is formed by patterning the metal film 214 (see FIG. 4F).

  Although the CMP method may be used for forming the metal plug 112, it is preferable to use the etch-back method for the recording head substrate 34. When the etch-back method is used, a combination of the metal plug material 110 and the upper-layer wiring material capable of securing a large etching selectivity with respect to the upper-layer wiring layer 216 (the material of the metal film 214), and the etching conditions at the time of the etch-back. Is important.

  As described above, in the recording head substrate 34, the metal film 214 serving as the upper wiring layer 216 is formed in the via hole 106 together with the surface 104a of the interlayer insulating film 104, and then the metal plug is formed on the metal film 214 in the via hole 106. 112 was formed. Thus, when the metal film 214 is formed by sputtering, the metal film 214 in the via hole 106 is covered with the metal plug 112 even if the coverage of the metal film 214 with respect to the side surface 106a (step portion) of the via hole 106 is low. Therefore, the upper wiring layer 216 formed from the metal film 214 is electrically connected to the lower wiring layer 102 via the metal plug 112 stably.

  In the recording head substrate 34, the metal film 214 formed after the formation of the via hole 106 is patterned to form the upper wiring layer 216. Therefore, the number of manufacturing steps can be reduced as compared with the recording head substrate 134 in which the metal film 114 and the upper wiring layer 116 are formed in different steps.

  Next, a method of forming the recording head substrate 34 on which the temperature sensing element and the heating resistor element required to be formed as a thin film as the upper wiring layer 216 will be described in detail. Note that the temperature detecting element is an element for detecting temperature information for determining whether or not the ink is normally ejected by the heating resistance element.

(Configuration of temperature sensing element)
First, a case where a temperature sensing element is configured as the upper wiring layer 216 will be described. The temperature detecting element is disclosed in, for example, JP-A-2007-290361. That is, in Japanese Patent Application Laid-Open No. 2007-290361, a heater (heating resistance element) as an ejection energy generating element is formed on a silicon substrate, and a thin film temperature detecting element is formed immediately below the heater via an interlayer insulating film. Is disclosed. Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 2007-290361, a temperature detection circuit detects temperature information from each temperature detection element, and compares a temperature change due to an ejection failure with a temperature change when ink is normally ejected. Then, it is determined whether or not the ink ejection is normal. The temperature detection is performed by monitoring a change in the electric resistance value of the temperature detection element according to the temperature change.

  It is preferable that such a temperature sensing element is a thin film and has a small heat capacity. The reason for this is that the temperature detecting element is disposed immediately below the heat generating resistance element, so that when the heat resistance is driven by a thick film, heat generated by driving the heat generating resistance element is absorbed by the temperature detecting element. As a result, an increase in the temperature of the heating resistor element is prevented, and the ejection efficiency is reduced. Further, when the heat capacity of the temperature detecting element is large, the temperature of the temperature detecting element itself hardly changes, and the responsiveness and sensitivity of the sensor are reduced, so that good detection characteristics cannot be obtained.

  For the above reasons, it is preferable that the temperature detecting element is a thin film and has a small heat capacity, and it is preferable that the temperature detecting element is disposed near the heating resistor element within a range that does not cause a decrease in ejection efficiency. For this reason, for example, a temperature detection element using a thin film resistance layer for temperature detection is connected to a lower wiring layer using a metal plug, and a heating resistance is connected via an interlayer insulating film planarized on the upper surface. The configuration in which the elements are arranged is effective.

  Note that the temperature detecting element has a configuration in which a constant current is applied to capture the voltage between both ends, thereby monitoring the electric resistance value of the temperature detecting element to detect the temperature. Therefore, in order to improve the temperature sensitivity, it is desirable that the resistance in the region for detecting the temperature located immediately below the heating resistance element is sufficiently larger than the wiring resistance of the wiring part of the wiring. For this reason, in the region, a configuration may be employed in which a plurality of linear patterns are folded to increase the resistance.

  Further, in the above-mentioned region, a characteristic in which the electric resistance changes according to the temperature change is required. The degree of such characteristics is indicated by a Temperature Coefficient of Resistance (TCR). The higher the value of TCR, the higher the sensitivity for detecting a temperature change. Generally, a metal used for semiconductor manufacturing has a smaller TCR in a state of being formed into a thin film than in a bulk state.

  In this embodiment, titanium is used as the metal used for the upper wiring layer as the temperature sensing element. Titanium has a high TCR of 2000 ppm / K or more even in a thin film of the order of several hundred nm. Therefore, the titanium thin film has high sensor characteristics.

  Normally, when an upper wiring layer and a lower wiring layer are connected by a metal plug, a titanium film is generally used as a contact metal for obtaining electrical connectivity with the lower wiring layer after opening a via hole in the interlayer insulating film. Material. Note that a titanium nitride film is formed as a diffusion prevention film on the contact metal.

  In the present embodiment, a stacked film of a titanium film and a titanium nitride film may be used as a metal film for forming an upper wiring layer as a temperature sensing element. The titanium nitride film has a low TCR, but has a higher specific resistance than the titanium film. Therefore, when a current is applied to the laminated film, the current flows through the titanium film having a lower resistance. Further, when the above-mentioned laminated film is used, the titanium film exhibits a high TCR, so that the characteristics of the titanium film, which is more excellent as a temperature sensing element, are dominantly exhibited.

  In the case where a stacked film of a titanium film and a titanium nitride film is used, the thickness of the titanium film is preferably larger than the thickness of the titanium nitride film in order to use a high TCR of the titanium film as a temperature detecting element. . In this case, since the resistance is reduced, the resistance may be increased by, for example, folding the linear pattern a plurality of times.

  By optimizing the conditions at the time of forming the metal film for forming the upper wiring layer, it is possible to form a film having a high TCR even with the same film thickness. Therefore, as the metal used for the upper wiring layer as the temperature detecting element, in addition to titanium, tungsten, aluminum, nickel, platinum and the like can be used. Further, as the upper wiring layer, a tungsten silicon nitride film or a tantalum silicon nitride film may be used instead of the metal film. Unlike a metal film, a tungsten silicon nitride film and a tantalum silicon nitride film have a negative TCR, and the resistance decreases as the temperature rises. These characteristics can be used as a temperature sensing element. .

(Formation of temperature sensing element)
Next, a method of forming the temperature detecting element on the recording head substrate 34 will be described.

  On the silicon substrate 100, a metal film for forming a lower wiring layer 102 connected to a MOS drive circuit or a logic circuit formed using a known semiconductor manufacturing technique is formed. This metal film is made of aluminum (Al) and copper (Cu) at 1.0 at. A film is formed on the substrate 100 by bipolar DC sputtering using an argon gas using an aluminum-copper alloy to which% is added.

  Next, an etching mask for patterning the metal film was formed on the metal film by a photolithography technique. Specifically, a positive photosensitive resist material serving as a mask is spin-coated on the substrate 100 (metal film) to form a resist film. Then, the resist film is subjected to i-line exposure through a photomask on which a wiring pattern is drawn, and is developed using an alkaline developer to form a resist pattern on the metal film.

  Thereafter, a region of the metal film which is not masked by the resist pattern is removed by dry etching to form a lower wiring layer 102 having a predetermined pattern. Specifically, a metal film is anisotropically etched by reactive ion etching (RIE) using a chlorine gas as an etching gas. Thereafter, an oxygen gas is introduced to remove the resist pattern by plasma ashing.

Subsequently, an interlayer insulating is performed on one surface of the substrate 100 on which the lower wiring layer 102 is formed by a plasma CVD method using dinitrogen monoxide (N ₂ O) and silane (SiH ₄ ) as a source gas. A silicon oxide film is formed as the film 104. At this time, an interlayer insulating film 104 made of a silicon oxide film was also formed using an HDP (High Density Plasma) oxide film on which a bias sputtering element was superimposed in combination with a lower layer portion. As a result, the silicon oxide film can be buried even in minute gaps between patterns in the lower wiring layer 102 without gaps.

  Next, the silicon oxide film (interlayer insulating film 104) is polished by an oxide film CMP method using an alkaline solution containing silica particles as a slurry to planarize the surface 104a of the interlayer insulating film 104 (FIG. 4A). Equivalent). Subsequently, in order to form a via hole 106 at a position of the interlayer insulating film 104 where the metal plug 112 is to be formed, a resist pattern having an opening in the via hole 106 is formed by photolithography. The photolithography technique used in this step may be, for example, the technique used when forming the lower wiring layer 102 described above, or another known technique.

Then, via holes 106 were formed in the interlayer insulating film 104 by inductively coupled plasma (ICP) reactive ion etching using carbon tetrafluoride (CF ₄ ) as an etching gas. Thereafter, oxygen gas is introduced, and the resist pattern is removed by plasma ashing (corresponding to FIG. 4B).

After that, a metal film 214 is formed on the surface 104 a of the interlayer insulating film 104 and in the via hole 106. That is, a laminated film in which a titanium film and a titanium nitride film are laminated is formed by long-throw DC sputtering film formation using an argon gas (corresponding to FIG. 4C). Note that the laminated film has a structure in which a titanium nitride film resistant to an etch-back process is laminated on the titanium film, thereby coping with damage at the time of the etch-back when forming the metal plug 112. . Subsequently, using tungsten hexafluoride (WF ₆ ) as a source gas, a blanket film is formed as a metal plug material 110 to a thickness enough to fill the via hole 106 by a low pressure CVD method (FIG. 4D). )).

Next, the metal plug material 110 (tungsten film) embedded in the via hole 106 is left by plasma etching using sulfur hexafluoride (SF ₆ ) as an etching gas, and the other metal plug materials 110 are removed. Thereby, the metal plug 112 is formed in the via hole 106 (corresponding to FIG. 4E). In this process, the metal film 214 is not removed, but remains on the interlayer insulating film 104 (on the insulating film).

  After that, a resist mask is formed on the metal film 214 (on the metal film) by using a photolithography technique. Then, the metal film 214 in a region where the resist mask is not covered is removed by dry etching, and the resist mask is removed by plasma ashing to form the upper wiring layer 216 (corresponding to FIG. 4F). As the photolithography technique, for example, the technique used when forming the lower wiring layer 102 described above or another known technique may be used.

(Configuration of heating resistor element)
Next, a case where the heating resistor element 48 is configured as the upper wiring layer 216 will be described. In order to suppress the drive current required to drive the heating resistor, it is desirable to increase the resistance of the heating resistor. For this reason, it is preferable to form the heat-generating resistor element in a thin film, and generally, the heat-generating resistive element is formed with a thickness of about several tens of nanometers. Further, since the heating resistance element is repeatedly driven, it is desirable that the temperature rise and fall of the heating resistance element itself be steep. For this reason, it is preferable that the heat generating resistance element is formed of a thin film resistor and the heat capacity is suppressed as small as possible.

  As the heat generating resistance element, a material such as tantalum silicon nitride or tungsten silicon nitride that exhibits stable resistance characteristics even in a high temperature environment can be used. These materials are used as heat generating resistance elements, but can also be used as a metal film (barrier metal) formed after opening a via hole. That is, the heating resistance element as the upper wiring layer may be configured using tantalum silicon nitride and also serving as a barrier metal.

(Formation of heating resistor element)
Next, a method of forming the heating resistance element on the recording head substrate 34 will be described.

  First, an interlayer insulating film 104 is formed on the lower wiring layer 102 formed on the silicon substrate 100 (corresponding to FIG. 4A), and a via hole 106 reaching the lower wiring layer 102 is formed in the interlayer insulating film 104 (FIG. 4A). FIG. 4B). Note that the processing up to this point is the same as the above-described step of forming the temperature sensing element, and thus a detailed description thereof will be omitted.

Next, a metal film 214 is formed on the surface 104 a of the interlayer insulating film 104 and in the via hole 106. That is, a tantalum silicon nitride film is formed by reactive sputtering using argon gas and nitrogen as reaction gases (corresponding to FIG. 4C). Subsequently, using tungsten hexafluoride (WF ₆ ) as a source gas, a blanket film is formed as a metal plug material 110 to a thickness enough to fill the via hole 106 by a low pressure CVD method (FIG. 4D). )).

After that, the metal plug material 110 (tungsten film) embedded in the via hole 106 is left by plasma etching using sulfur hexafluoride (SF ₆ ) as an etching gas, and the other metal plug material 110 is removed. Thereby, the metal plug 112 is formed in the via hole 106 (corresponding to FIG. 4E). In this process, the metal film 214 is not removed and remains on the interlayer insulating film 104.

  Subsequently, a resist mask is formed on the metal film 214 by using a photolithography technique. Then, the metal film 214 in a region where the resist mask is not covered is removed by dry etching, and the resist mask is removed by plasma ashing to form the upper wiring layer 216 (corresponding to FIG. 4F). As the photolithography technique, for example, the technique used when forming the lower wiring layer 102 described above or another known technique may be used.

  As described above, in the recording head substrate 34, the interlayer insulating film 104 in which the via hole 106 reaching the lower wiring layer 102 is formed and the thin metal film 214 formed in the via hole 106 are formed as the upper wiring layer 216. did. Then, the metal plug 112 is formed on the metal film 214 (upper wiring layer 216) in the via hole 106.

  Thus, even if the metal film 214 is formed as a thin film by sputtering with low coverage on the stepped portion, the metal film 214 in the via hole 106 is covered with the metal plug 112. That is, the step portion where the metal film 214 may not be properly formed is covered with the metal plug 112. Therefore, the upper wiring layer 216 formed from the metal film 214 is electrically connected to the lower wiring layer 102 stably. Therefore, according to the present invention, it becomes possible to electrically stably connect the heating resistor element and the temperature detecting element, which are required to be formed of a thin film, to a wiring layer such as a drive circuit.

  Also, since a metal film such as a barrier metal is used as the upper wiring layer, the number of steps is reduced and the manufacturing cost is reduced as compared with a case where the metal film and the upper wiring layer are separately formed. it can.

(Other embodiments)
The above embodiment may be modified as shown in the following (1) to (3).

  (1) Although not specifically described in the above embodiment, the metal plug 112 is formed on the upper wiring layer 216 (on the second wiring layer) for both the temperature detecting element and the heating resistor element in the recording head substrate 34. The configuration may be such that:

  FIG. 5A is a diagram illustrating a temperature detection element and a heating resistance element provided corresponding to the ejection port 46 in the print head substrate 34. FIG. 5B is a diagram in which the temperature detecting element of FIG. 5A has a structure in which a linear pattern is folded. FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG.

  First, the temperature detecting element 50 is formed by the method described in the above embodiment. Next, an interlayer insulating film is formed on the temperature sensing element 50, and the upper surface of the interlayer insulating film is flattened by the CMP method. After that, the heating resistance element 48 is formed by the method described in the above embodiment. Then, a passivation film such as a silicon nitride film and a protective film 200 such as a cavitation-resistant film such as tantalum are formed, and the recording head substrate 34 is manufactured.

  After that, the flow path forming member 36 is formed on the recording head substrate 34 using a photosensitive resin by using a photolithography technique. At this time, the pressure chamber 38 and the discharge port 46 are formed. Further, the recording head 26 is formed by forming an ink supply port 40 for supplying ink from the back surface of the substrate, that is, the other surface 34b of the recording head substrate 34 by using silicon anisotropic etching or the like. Is done.

  (2) In the above embodiment, the recording head unit 16 is configured such that the ink tank 28 is integrated, but the present invention is not limited to this. For example, the recording head 26 and the ink tank 28 may be configured separately. Thus, when the ink in the ink tank 28 runs out, only the ink tank 28 can be replaced. Further, for example, the recording head 26 and the ink tank 28 are arranged at positions separated from each other, and these are connected via a tube or the like so that ink is supplied from the ink tank 28 to the recording head 26. Is also good. In the above-described embodiment, the printing apparatus 10 employs a serial scan system in which the print head unit 16 performs printing while moving in the scanning direction via the carriage 14, but the printing apparatus 10 is not limited to this. That is, a full-line system may be used in which recording is performed by a recording head extending over a range corresponding to the entire width of the recording medium.

  (3) In the above embodiment, titanium and titanium nitride are used as the material of the metal film 214 (upper wiring layer 216), but the material is not limited to this. That is, tantalum and tantalum nitride may be used. In this case, the metal film 214 is a stacked film of a tantalum film and a tantalum nitride film. In the above embodiment, the metal film 214 is formed as a thin film. However, the present invention is not limited to this. That is, the metal film 214 may be formed as a film thicker than 300 nm.

34 Printhead substrate 102 Lower wiring layer 104 Interlayer insulating film 106 Via hole 112 Metal plug 216 Upper wiring layer

Claims (17)

A first wiring layer formed on the substrate,
A second wiring layer formed on the first wiring layer via an insulating film;
A liquid ejection head substrate, comprising: a plug provided in a hole formed in the insulating film so as to reach the first wiring layer, the plug being capable of electrically connecting the first wiring layer and the second wiring layer. And
The second wiring layer is formed inside the hole and on the insulating film;
The substrate for a liquid ejection head, wherein the plug is formed on the second wiring layer in the hole.   2. The substrate according to claim 1, wherein the second wiring layer has a thickness of 10 nm to 300 nm. 3.   3. The liquid discharge head substrate according to claim 1, wherein the second wiring layer is made of titanium and titanium nitride, or tantalum and tantalum nitride.   3. The liquid discharge head substrate according to claim 1, wherein the second wiring layer is made of tantalum silicon nitride or tungsten silicon nitride.   The liquid discharge head substrate according to any one of claims 1 to 4, wherein the second wiring layer forms a heating resistor element.   The liquid discharge head substrate according to any one of claims 1 to 4, wherein the second wiring layer forms a temperature detection element.   The substrate according to claim 6, wherein the second wiring layer is formed by folding a plurality of linear patterns. A method for manufacturing a substrate for a liquid ejection head, wherein a first wiring layer and a second wiring layer formed via an insulating film can be electrically connected by a plug,
Forming the insulating film on the substrate on which the first wiring layer is formed;
Forming a hole reaching the first wiring layer in the insulating film;
Forming a metal film inside the hole and on the insulating film;
Forming a film with a plug material on the metal film so as to fill the inside of the hole,
Removing the plug material while leaving the plug material inside the hole;
Forming a second wiring layer by patterning the metal film.   9. The method according to claim 8, wherein the metal film has a thickness of 10 nm to 300 nm.   The method according to claim 8, wherein the metal film is made of titanium and titanium nitride, or tantalum and tantalum nitride.   10. The method according to claim 8, wherein the metal film is made of tantalum silicon nitride or tungsten silicon nitride.   12. The method according to claim 8, wherein the second wiring layer forms a heating resistor.   The method according to claim 8, wherein the second wiring layer forms a temperature sensing element.   14. The method according to claim 13, wherein the second wiring layer is formed by folding a linear pattern a plurality of times.   The method for manufacturing a substrate for a liquid ejection head according to claim 8, wherein the metal film is formed by sputtering.   A liquid discharge head in which discharge of liquid is controlled by the liquid discharge head substrate according to any one of claims 1 to 7.   A liquid ejection apparatus for ejecting liquid by the liquid ejection head according to claim 16.

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