JP2008238734A - Electronic device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device and its manufacturing method enabling formation of fine patterns by wet etching. <P>SOLUTION: The electronic device is provided characterized by having a resistance heat generator which generates heat when power is distributed, an electrode connected to the resistance heat generator, a protective film covering at least part of the electrode, and a TiN film covering approximately the entire surface of the protective film. The manufacturing method of the electronic device characterized by forming a first layer, forming a TiN film on the first layer, and etching part of the first layer by wet etching by using the TiN film as a mask. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic device and a manufacturing method thereof, and more particularly to an electronic device such as a thermal printer head having a heating resistor and a protective film and a manufacturing method thereof.

  In an electronic device such as a thermal printer head, a resistance heating element is formed on an insulating substrate made of ceramics or the like so as to form a set of circuits together with electrodes, and a plurality of the heating elements are arranged substantially linearly. Further, a protective film made of an insulating material is formed so as to cover at least the resistance heating element row. Then, in a state where the print paper is pressure-bonded to the upper surface of the protective film via an ink ribbon, or in a state where the thermal paper is pressure-bonded to the upper surface of the protective film, a pulse current is passed through the resistance heating element to generate heat, Print.

  Since the protective film is in direct contact with the print paper and the ink ribbon, the protective film is formed thick. Therefore, not only a long time is required for film formation, but also a long time is required for forming a contact hole for the protective film. For forming the contact hole, a dry etching technique such as RIE (Reactive Ion Etching) is used, but the thickness of the protective film is as thick as 5 to 7 microns, for example, 90 minutes. Therefore, from the viewpoint of equipment costs, there is a demand for a shift to wet etching that can reduce costs.

  Further, a film resist is used as a mask for etching by RIE. However, since the thickness is thick, the resolution is limited. Specifically, it is not suitable for forming contact holes smaller than about 200 microns × 50 microns.

On the other hand, in order to wet-etch the insulating protective film, an HF (hydrofluoric acid) -based etchant is used as an etchant. However, in a general mask, the mask is peeled off during etching, and the thick protective film is etched for a long time. I can't.
Further, when an HF-based etchant is used as an etchant, there is a problem that overetching is caused because the selection ratio with the underlying Al (aluminum) electrode cannot be obtained.
In addition, the insulator protective film is charged due to friction with the printing paper during printing, and this charging causes a problem of electrostatic breakdown. In addition, there is a problem that mechanical strength such as wear resistance is insufficient.

  Therefore, it is desired that the protective film is processed using a mask that is suitable for wet etching and that can be miniaturized, and that the wet etching has a sufficient selectivity with respect to the underlying Al electrode layer. In addition, improvements such as suppressing charging of the insulator protective film and improving wear resistance are desired.

As the insulating protective film material, a glass film, SiON, SiAlON, SiO ₂ , Si ₃ N _{4 and the} like are disclosed in Patent Document 1 and the like. In addition, Patent Document 2 discloses an example in which a mixture of chromium oxide and a refractory metal nitride or a mixture of chromium oxide and a refractory metal carbide is formed on the protective film for the purpose of improving wear resistance. However, microfabrication is difficult.

On the other hand, there is a technique in which a protective film is coated on a protective film for the purpose of preventing the protective film from being corroded by impurity ions entering the protective film from print paper or the like due to the electric field applied to the protective film. 3 is disclosed.
JP 2000-246929 A Japanese Patent Laid-Open No. 7-68816 JP 2004-230583 A

  The present invention provides an electronic device capable of forming a fine pattern by wet etching and a manufacturing method thereof.

  According to one aspect of the present invention, a resistance heating element that generates heat when energized, an electrode connected to the resistance heating element, a protective film covering at least a part of the electrode, and a substantially entire surface of the protective film There is provided an electronic device comprising: a TiN film covering the surface.

  According to another aspect of the present invention, a first layer is formed, a TiN film is formed on the first layer, and one of the first layers is formed by wet etching using the TiN film as a mask. There is provided a method for manufacturing an electronic device characterized by etching a portion.

  According to still another aspect of the present invention, an electrode is formed, a first layer is formed so as to cover at least a part of the electrode, the first layer is covered with a TiN film, and the TiN film is formed. A method for manufacturing an electronic device is provided, wherein the electrode is exposed by etching a part of the first layer by wet etching using a mask as a mask.

  ADVANTAGE OF THE INVENTION According to this invention, the electronic device which can form a fine pattern by wet etching, and its manufacturing method are provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional view illustrating an element structure of an electronic device according to the present embodiment, more specifically, a thermal printer head.
FIG. 2 is a partial perspective view of the thermal printer head.

  In the thermal printer head 1 of the present embodiment, an insulating substrate 2 is provided. As a material of the insulating substrate 2, for example, an alumina ceramic substrate made of alumina is used. A water glass layer 3 made of water glass, for example, is provided on the upper surface of the insulating substrate 2. A part of the upper surface of the water glass layer 3 is formed with a bowl-shaped convex portion 3a extending in one direction.

On the water glass layer 3, for example, a plurality of resistance heating elements 4 made of Ta—SiO ₂ are formed over the entire region. Further, for example, electrodes 5 a and 5 b made of a material mainly composed of Al are formed so as to cover the resistance heating element 4. The electrodes 5a and 5b and the resistance heating element 4 form a set of circuits, and a plurality of them are provided so as to be arranged in a substantially straight line.

  Further, a protective film 7 is provided so as to cover the water glass layer 3, the resistance heating element 4, and the electrodes 5a and 5b. The shape of the protective film 7 reflects the shape of the water glass layer 3, and a convex portion 7 a is formed in a region corresponding to the convex portion 3 a of the water glass layer 3. The protective film 7 is made of, for example, SiON.

  In addition, the protective film 7 is covered with a TiN film 8 that is a mask for etching the protective film 7. That is, almost the entire surface of the protective film 7 is covered with the TiN film 8. That is, there is substantially no portion where the protective film 7 is exposed without being covered with the TiN film 8. The shape of the TiN film reflects the shape of the protective film 7, and the region corresponding to the convex portion 7a of the protective film 7 is curved to form the convex portion 8a. A contact hole 10 formed by etching the protective film 7 using the TiN film 8 as a mask is formed at the end of the electrode 5a far from the electrode 5b. By providing the TiN film 8 having high hardness, the wear resistance of the protective film can be improved. Further, since the TiN film 8 is conductive, if it is connected to the ground or the like, it can act as a charge removal film for preventing charge-up. Furthermore, by using the TiN film 8 as a mask, high selectivity with respect to the HF-based etchant can be obtained, and the thick protective film 7 can be reliably processed by wet etching. Furthermore, since the TiN film 8 can be easily patterned with a hydrogen peroxide-based etchant, fine processing can be carried out reliably and easily.

Details of the connection between the driver IC 15 of the thermal print head of this embodiment and the thermal head substrate will be described below with reference to FIG.
A driver IC (circuit element) 15 is mounted on the insulating substrate 2, and an end of the electrode 5 a that is not connected to the resistance heating element 4 is connected to a terminal of the driver IC 15. For example, four electrodes 5a are connected to one driver IC 15. Further, a resin substrate 31 is provided on the side of the insulating substrate 2 on the driver IC 15 side, and is on the same plane as the upper surface and the lower surface of the insulating substrate 2, respectively. A plurality of wiring layers 32 are formed on the resin substrate 31, and the wiring layers 32 are connected to terminals of the driver IC 15 to which the electrodes 5a are not connected.

  Furthermore, an encap 33 made of resin is provided on the insulating substrate 2 and the resin substrate 31 so as to cover the connection portion of the driver IC 15 and the electrode 5a and the wiring layer 32 with the driver IC 15. For example, an IC cover 34 formed by bending a resin plate is provided so as to cover the cap 33. On the other hand, a heat sink 35 and a connector 36 are connected to the lower surfaces of the insulating substrate 2 and the resin substrate 31. Terminals of the connector 36 are connected to the wiring layer 32.

The operation of the thermal printer head 1 according to this example configured as described above will be described.
A roller 11 is disposed above the convex portion 8 a of the TiN film, and the ink ribbon 12 and the print paper 13 are sandwiched between the roller 11 and the convex portion 8 a of the TiN film 8. The ink ribbon 12 is pressed against the convex portion 8 a by the roller 11 through the print paper 13. Here, when the roller 11 rotates, the ink ribbon 12 and the print paper 13 move with respect to the thermal printer head 1, and the ink ribbon 12 slides with respect to the convex portion 8a.

  In this state, when the driver IC 15 selectively allows a pulse current to flow through the path composed of the electrode 5a, the resistance heating element 4 and the electrode 5b based on a signal input via the connector 36, the pulse current is The resistance heating element 4 flows through the resistance heating element 4 immediately below the convex portion 8a, and generates heat. This heat is conducted through the protective film 7 and the TiN film 8 and is transmitted to the contact portion of the ink ribbon 12 with respect to the convex portion 8 a, and the ink component in the ink ribbon 12 is transferred to the print paper 13. As a result, the ink layer 14 is formed on the print paper 13 and printed.

  According to this example, as described above, the TiN film 8 is provided on the protective film 7, the TiN mask is formed, and the protective film 7 is processed, so that miniaturization and processing time can be shortened. It becomes. Furthermore, since the TiN film 8 can be printed in a state of covering the protective film 7, it is possible to improve the wear resistance. Further, since TiN has conductivity, it is possible to remove the charge generated by sliding.

Below, the manufacturing method of the thermal printer head 1 which concerns on this example is demonstrated.
FIG. 3 is a flowchart showing a method for manufacturing the thermal printer head 1 according to this example.
First, as shown in step S <b> 1 of FIG. 3, for example, water glass is applied and baked on the insulating substrate 2 to form the water glass layer 3. On the water glass layer 3, a bowl-shaped convex portion 3 a extending in one direction is formed.

Next, as shown in step S2, a resistance heating element layer made of Ta—SiO ₂ is formed on the water glass layer 3 by sputtering, for example.
Next, as shown in step S3, an electrode layer made of, for example, Al is formed on the resistance heating element layer, patterning is performed, and the resistance heating element 4 is formed on the convex portion 3a of the water glass layer 3. Electrodes 5a and 5b are formed. The resistance heating element 4 and the electrodes 5a and 5b constitute a set of circuits, and are provided so that a plurality of them are arranged in a substantially straight line.

Next, as shown in steps S4 to S9, the protective film 7 is formed and processed.
FIG. 4 is a cross-sectional view of the stacked films in each step of etching the protective film 7. FIG. 4a shows a cross-sectional view of the film at the stage where the protective film 7 is formed. A protective film 7 is formed so as to cover the resistance heating element 4 and the electrodes 5a and 5b. For example, SiON is formed to a thickness of 5 to 7 microns by RF sputtering. On the insulating substrate 2, water glass layer 3, Ta-SiO ₂ resistive heating element 4 consisting of, an Al electrode 5a and 5b, the protective film 7 made of SiON are sequentially stacked.

  Next, as shown in step S5, a TiN film 8 serving as a mask for wet-etching the protective film 7 is formed on the protective film 7 by, for example, a sputtering method. The film is formed to have a thickness of about 200 nm, for example. FIG. 4b shows a cross-sectional view of the laminated film at this stage.

Next, as shown in steps S6 to S8, a resist 9 is applied and developed on the TiN film 8 (S6), and the TiN film 8 is etched with an H ₂ O ₂ etchant using the resist 9 as a mask. Is processed into a predetermined shape (S7). FIG. 4c shows a cross-sectional view of a laminated film obtained by processing the TiN film 8 into a predetermined shape. TiN is insoluble in the HF solution and has high adhesion to the insulating film in the solution. Therefore, the thick protective film 7 is etched in a later process, but is not peeled off in that process, and the TiN process may be performed using a general resist mask and H ₂ O _2. Processing is possible. FIG. 4d shows a cross-sectional view of the laminated film at the stage where the resist 9 is removed and a TiN mask is formed (S8).

  Next, as shown in step S9, wet etching of the protective film 7 is performed using the processed TiN film 8 as a mask. As the etchant, an HF + KF type etchant in which KF is mixed with HF is used. In the etching of the protective film 7, SiON that is a constituent material of the protective film 7 is etched, but Al that is a constituent material of the electrodes 5a and 5b is preferably not etched. That is, high etching selectivity is desired. By using an HF + KF-based etchant, it is possible to perform etching of SiON constituting the protective film 7 while suppressing the etching rate of Al small. FIG. 4e shows a state where the protective film 7 has been etched.

  Next, as shown in step S10, the driver IC 15 is connected. This connection is made through the contact hole 10. A driver IC 15 is mounted on the insulating substrate 2, and an end of the electrode 5a on the side far from the electrode 5b is connected to a terminal of the driver IC 15. Further, the wiring layer 32 is formed on the resin substrate 31, the resin substrate 31 is connected to the side portion of the insulating substrate 2, and the wiring layer 32 is connected to the other terminal of the driver IC 15. Further, an encap 33 made of resin is formed on the upper surfaces of the insulating substrate 2 and the resin substrate 31 so as to cover the driver IC 15 and the electrode 5a and the connection portion to the driver IC 15 in the wiring layer 32. An IC cover 34 is attached so as to cover 33. A heat sink 35 and a connector 36 are attached on the lower surfaces of the insulating substrate 2 and the resin substrate 31. Thus, the thermal printer head 1 is manufactured.

  After the etching of the protective film 7 in the above step S9, the TiN film can be connected to the ground to have a function as a charge removal film, and can be used as a wear-resistant film by utilizing the hard characteristics of TiN. It is also possible to do. You may utilize as both a static elimination film and an abrasion-resistant film | membrane.

A mechanism for obtaining high selectivity between the SiON used for the protective film 7 and the Al of the electrode 5a when an HF + KF-based etchant is used will be described.
FIG. 5 is a Pourbaix (pool bay) diagram of Al, in which the Al presence region in water is represented on two-dimensional coordinates of electrode potential and pH. Al dissolves in the acidic region where the pH value is low, but enters the passive region and stabilizes as the pH value increases. The addition of KF to ^{HF, KF = K + + F} - equilibrium moves to the left ^- HF ^{= H} + + F by ion ^- F generated by. With this equilibrium transfer, the hydrogen ion concentration decreases, and when the pH value is 5.2 or more, the Al etching does not proceed because the Al passivated region is entered as shown in the Al Pourbaix diagram. Therefore, it is possible to obtain a very high etching rate selectivity between SiON and Al by appropriately selecting the amount of KF added.

  FIG. 6 shows the etching rate of SiON and Al with respect to the HF concentration at room temperature when 40 g of KF was added to 100 ml of HF solution. In an HF solution having an HF concentration of 34.3% or less, when 40 g of KF is added to 100 ml of HF, Al forms a passive film, and the etching rate is significantly reduced. Since it is difficult to measure the etching rate of Al in the Al passive region, FIG. 6 shows that the etching rate is 1 nm / min or less with respect to the HF concentration of 34.3% or less. When the HF concentration is 34.3% or less, the etching rate of SiON is approximately 50 to 80 nm / min. Therefore, it is considered that it is easy to obtain a selection ratio of two digits or more.

  FIG. 7 shows the temperature dependence of the etching rate for SiON by the HF + KF-based etchant. The case where the HF concentration is 29% and 34% is shown. A high etching rate is obtained for SiON at high temperatures, and it is considered that the problem of throughput is solved. For example, when 40 g of KF is added to 100 ml of 29% HF solution and heated to 45 ° C., the etching rate for SiON is 200 nm / min, and 5 μm thick SiON is etched in about 25 minutes. be able to. It can be said that this sufficiently satisfies the manufacturing requirement of processing a thick protective film in a short time. As a comparative example, although not shown, in the case of a 49% HF concentration etchant at room temperature without adding KF, the etching rate was 145 nm / min and the SiON / Al selectivity was 3.5.

In this specific example, TiN is selected as a mask for wet etching of the insulator protective film. Various organic materials were studied as a mask that does not peel off during wet etching, but none of them was suitable, and TiN was effective as a metal mask material. TiN, Cu, Mo, and Ni were compared as metal masks.
FIG. 8 shows the surface morphology of TiN, Cu, Mo and Ni when 40 g of KF is added to 100 ml of 29% HF solution to form KF + HF etchant and etched at 45 ° C. for 37 minutes for 30 seconds. The TiN surface was stable before and after etching and was stable, but Cu, Mo, and Ni caused peeling or pitting corrosion and could not be used as an etching mask.

  From the above results, it is possible to manufacture the thermal printer head 1 having a miniaturized pattern at low cost by using the TiN film 8 as a mask and performing wet etching with an HF + KF-based etchant for processing the protective film 7. It has become possible. In order to form the fine contact hole 10, it is necessary to coat the TiN film 8 so as to cover the entire surface of the protective film 7, produce a TiN mask, and etch the protective film 7. 6 is different from the coating region of the conductive film shown in FIG. 2 and the coating region of the TiN film 8 in the present invention. The purpose of forming the conductive film is also different.

  Further, by covering the protective film 7 with the TiN film 8, it becomes possible to improve wear resistance and prevent charging.

  In the above-described specific example, an example is shown in which the thermal printer head is applied to an ink ribbon type printer. However, the present invention is not limited to this, and for example, the present invention is applied to a thermal printer that does not use an ink ribbon. Also good.

Further, as the protective film 7 has been described example using SiON, SiO and the like SiO _2, SiN or such as _Si 3 _{N 4,} may be used SiAlON or, or an oxide such as glass paste fired film . Furthermore, the formation method of each layer which comprises a specific example can be suitably selected in consideration of the ease of formation, film quality, and the like.
Furthermore, the present invention can be applied to any electronic device having a structure in which the protective film is an oxide system and the base is Al, and is included in the scope of the present invention.

1 is a partial cross-sectional view illustrating an electronic device according to an embodiment of the invention. 1 is a partial perspective view illustrating an electronic device according to an embodiment of the invention. It is a flowchart figure which illustrates the manufacturing method of the electronic device which concerns on embodiment of this invention. It is sectional drawing of the laminated film in each step of a protective film etching process. It is a Pourbaix diagram of Al. This is the concentration dependency of the etching rate by the HF + KF-based etchant. This is the temperature dependence of the etching rate by the HF + KF-based etchant. This is a mask surface form after etching with an HF + KF-based etchant.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Thermal printer head, 2 Insulating substrate, 3 Water glass layer, 3a Convex part, 4 Resistance heating element, 5a, 5b Electrode, 7 Protective film, 7a Convex part, 8 TiN film, 8a Convex part

Claims (11)

A resistance heating element that generates heat when energized;
An electrode connected to the resistance heating element;
A protective film covering at least a part of the electrode;
A TiN film covering substantially the entire surface of the protective film;
An electronic device comprising:   The electronic device according to claim 1, wherein the electrode is made of a material mainly composed of aluminum.   2. The electronic device according to claim 1, wherein the protective film is etched using the TiN film as a mask.   The electronic device according to claim 1, further comprising a contact hole that penetrates the TiN film and the protective film and reaches the electrode. A circuit element,
The electronic device according to claim 4, wherein the circuit element and the electrode are connected through the contact hole.   The electronic device according to claim 1, wherein the protective film is selected from the group consisting of SiON, SiO, SiN, SiAlON, and a glass paste sintered body. Forming a first layer;
Forming a TiN film on the first layer;
Using the TiN film as a mask, a part of the first layer is etched by wet etching. Forming electrodes,
Forming a first layer so as to cover at least part of the electrode;
Coating the first layer with a TiN film;
Using the TiN film as a mask, a part of the first layer is etched by wet etching to expose the electrode.   9. The method of manufacturing an electronic device according to claim 7, wherein an HF-based etchant is used in the wet etching. The electrode is made of a material mainly composed of aluminum,
9. The method of manufacturing an electronic device according to claim 8, wherein a mixed etchant of an HF-based etchant and a KF-based etchant is used in the wet etching.   11. The electron according to claim 7, wherein the first layer is made of any one selected from the group consisting of SiON, SiO, SiN, SiAlON, and a glass paste sintered body. Device manufacturing method.