JP2013038393A - Multilayer wiring film for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer wiring film for an electronic component which improves oxidation resistance while maintaining the advantages, i.e., the Si barrier and the ITO contact of Mo, and can maintain a low electric resistance even during lamination with Cu or after a heating process for fixing a signal cable, or the like.SOLUTION: A multilayer wiring film for an electronic component having a metal film formed on a substrate consists of a main conductive layer composed of Cu, and a coating layer covering one or the other surface of the main conductive layer. The coating layer is composed of an Mo-Ni alloy having a composition formula in the atomic ratio of MoNi, 10≤X≤70, and the reminder of inevitable impurities.

Description

  The present invention relates to a flat display device (flat panel display, hereinafter referred to as FPD) such as a liquid crystal display (hereinafter referred to as LCD), a plasma display panel (hereinafter referred to as PDP), an electrophoretic display used in electronic paper, and the like. In addition, the present invention relates to a multilayer wiring film for electronic components used for various semiconductor devices, thin film sensors, thin film electronic components such as magnetic heads, and the like.

FPDs such as LCDs, PDPs, and organic EL displays that produce thin film devices on a glass substrate are required to have a large screen, high definition, and high-speed driving for eliminating moving image blur. For the main conductive layer of a thin film transistor (TFT) used as an FPD driving element, it is necessary to reduce the resistance for the above high-speed driving, and the material of the main conductive layer is lower than that of Al. Consideration is being made to change to Cu.
In addition, new products such as touch panels that add operability to FPDs and flexible FPDs using resin substrates are also being developed. In these cases, studies are underway to use Cu as the main conductive layer to reduce resistance. Yes.

Currently, Si semiconductor films are mainly used for TFTs. When Cu is used as the main conductive layer in such a TFT, if Cu is in direct contact with Si, Cu atoms are thermally diffused in the Si semiconductor film constituting the TFT in the heating process during TFT manufacture. May deteriorate the characteristics. In order to prevent this phenomenon, a laminated wiring film is used in which a barrier film made of Mo or Mo alloy having excellent heat resistance is provided between the main conductive layer made of Cu and the Si semiconductor film.
In addition, ITO (indium-tin oxide), which is a transparent conductive film, is generally used for a pixel electrode connected to a TFT, or a position detection electrode of a touch panel used in a portable terminal, a tablet PC, or the like. Cu can be contacted with ITO, but has low adhesion to the substrate. Therefore, a laminated wiring film in which Cu that can secure adhesion is coated with Mo or Mo alloy is effective.

  The present applicant employs a laminated wiring film in which a film mainly composed of Cu having low adhesion to glass or the like and a Mo alloy mainly containing Mo and containing V and / or Nb are used. It has been proposed that the corrosion resistance, heat resistance and adhesion of the wiring film can be improved while taking advantage of the low electrical resistance value of Ag (Patent Document 1).

JP 2004-140319 A

The Mo alloy mainly composed of Mo and containing V and / or Nb proposed in the above-mentioned Patent Document 1 is more widely used in FPD applications formed on a glass substrate because it has better corrosion resistance, heat resistance, and adhesion than pure Mo. Has been.
However, in the manufacture of electronic components, after forming the laminated wiring film on the substrate, when moving the substrate to the next process, or in the heating process when attaching the signal cable to the terminal part etc. for touch panel applications, May be exposed to prolonged exposure. According to the study by the present inventor, when the above-described laminated wiring film is heated in the atmosphere, the oxidation resistance is not sufficient, and there arises a problem that the oxidation resistance is deteriorated such that the laminated wiring film is discolored. There is a case. This problem of a decrease in oxidation resistance deteriorates the electrical contact properties and leads to a decrease in the reliability of the electronic component.
In addition, the heating temperature during the TFT manufacturing process tends to increase due to high-speed driving, and when the heating process is performed at a higher temperature, the alloy element contained in the laminated wiring film diffuses into Cu and the electric resistance value is increased. May increase. In order to maintain a low electrical resistance after the heating process, it is necessary to prevent undesirable diffusion of the alloy elements.

  The object of the present invention is to improve the oxidation resistance while maintaining the advantages of Mo such as Si barrier property and ITO contact property, and also to perform heating processes such as lamination with Cu and attachment of signal cables. It is to provide a laminated wiring film for electronic parts that can maintain a low electric resistance value even after passing.

  As a result of various studies in view of the above problems, the present inventor has improved the oxidation resistance in the atmosphere by forming a coating layer with a Mo—Ni alloy in which a specific amount of Ni is added to Mo, and further comprises Cu. The present inventors have found that a low electrical resistance value can be maintained even after a heating process such as a lamination with a main conductive layer or a signal cable is attached.

That is, the present invention comprises a main conductive layer made of Cu and a coating layer covering one surface and / or the other surface of the main conductive layer in a multilayer wiring film for electronic components in which a metal film is formed on a substrate. The coating layer is an invention of a laminated wiring film for electronic parts, in which the composition formula in atomic ratio is represented by Mo _100-X Ni _X , 10 ≦ X ≦ 70, and the balance is a Mo—Ni alloy composed of inevitable impurities. .
In the present invention, X in the composition formula is preferably in the range of 20-50.
Moreover, in this invention, it is preferable that the thickness of the said coating layer is 10-200 nm.
In the present invention, the main conductive layer preferably has a thickness of 100 to 500 nm.

  The multilayer wiring film for electronic parts of the present invention can improve oxidation resistance while maintaining the excellent characteristics of Mo. As a result, it can greatly contribute to stable production and improved reliability of various electronic components including a flexible FPD formed on a touch panel or a resin substrate.

It is a cross-sectional schematic diagram which shows an example of the laminated wiring film for electronic components of this invention.

  FIG. 1 is a schematic cross-sectional view showing an example of the laminated wiring film for electronic parts of the present invention. As shown in FIG. 1, the laminated wiring film for electronic components of the present invention comprises coating layers 2 and 4 covering one surface and / or the other surface of a main conductive layer 3 mainly composed of Cu. 1 is formed. In FIG. 1, coating layers 2 and 4 are formed on both surfaces of the main conductive layer 3, but depending on the form of the electronic component, only one surface of the main conductive layer 3 may be covered. It can be selected as appropriate.

  An important feature of the present invention is that oxidation resistance is improved by adding a specific amount of Ni to Mo in the coating layer of the multilayer wiring film for electronic parts shown in FIG. Even if it passes through heating processes, such as attachment, it exists in the point which can maintain the low electrical resistance value as a laminated wiring film. The laminated wiring film for electronic parts of the present invention will be described in detail below.

When a pure Mo film is heated in the air, the surface is oxidized and the electrical contact properties are deteriorated. The coating layer of the multilayer wiring film for electronic parts of the present invention has an effect of improving oxidation resistance by adding a specific amount of Ni to Mo. The effect is that the amount of Ni added starts from 10 atomic%, and when 20 atomic% or more is added, an increase in electrical resistance value can be suppressed even after high-temperature heating in the atmosphere.
On the other hand, Ni is an element that is more easily thermally diffused with respect to Cu than Mo. When the amount of Ni exceeds 70%, Ni contained in the coating layer is not heated in the heating process for manufacturing electronic parts such as FPD. Diffusing into Cu of the main conductive layer makes it difficult to maintain a low electrical resistance value. For this reason, a coating layer makes Ni amount added to Mo 10-70 atomic%.

In order to further suppress oxidation in the atmosphere, the amount of Ni added to Mo is preferably set to 20 atomic% or more. If Cu of the main conductive layer is heated at 200 ° C. or higher in the atmosphere without forming a coating layer, it may be easily oxidized and discolored, and the electrical contact property may be deteriorated. In the present invention, the surface of Cu of the main conductive layer is covered with a coating layer made of a Mo—Ni alloy, and in order to block the intrusion of oxygen and suppress the oxidation of Cu, the Ni addition amount of the coating layer has a sufficient effect. It is preferable to make it 20 atomic% or more obtained.
Further, in order to suppress an increase in the electric resistance value of Cu of the main conductive layer due to thermal diffusion of Ni atoms in a high temperature range, it is preferable to make Ni 50 atomic percent or less.

  In the multilayer wiring film for electronic parts of the present invention, the Cu film thickness of the main conductive layer is less than 100 nm because of the influence of the surface grain boundaries and grain boundary scattering of the thin film. The electrical resistance value tends to increase. On the other hand, if the thickness of the main conductive layer is too thick, it takes a long time to form the film, and the substrate is likely to warp due to film stress. For this reason, the film thickness of the main conductive layer of the present invention is preferably 100 to 500 nm.

In the multilayer wiring film for electronic parts of the present invention, if the film thickness of the Mo—Ni alloy as the coating layer is less than 10 nm, the continuity of the Mo—Ni alloy film is lowered and the oxidation resistance is improved. It may not be enough. On the other hand, when the film thickness of the coating layer is too thick, it takes time to form the film, or the electric resistance value of the Mo—Ni alloy film is high. In addition, the electrical resistance value increases, making it difficult to obtain a low electrical resistance value as a laminated wiring film. For this reason, it is preferable that the coating layer of this invention is 10-200 nm.
In addition, the coating layer of the present invention needs to obtain a sufficient effect of blocking oxygen as an upper layer film of Cu, and more preferably has a thickness of 30 nm or more. On the other hand, when the film thickness of the coating layer is greater than 100 nm, the substrate is likely to warp due to film stress. For this reason, the film thickness of the coating layer of the present invention is more preferably 30 to 100 nm.

  Moreover, in order to form the multilayer wiring film for electronic components of the present invention, a sputtering method using a target is suitable. As the sputtering method, a method of forming a film using a Mo—Ni alloy target material having the same composition as the composition of the coating layer, a co-sputter film forming method of simultaneously sputtering using each target material of Mo and Ni, etc. are applied. it can. From the viewpoint of easy setting of sputtering conditions and easy to obtain a wiring thin film having a desired composition, it is most preferable to perform sputtering film formation using a Mo—Ni alloy target material having the same composition as that of the coating layer. Similarly, the main conductive layer is preferably formed by sputtering using a Cu target material.

  In the Mo—Ni alloy target material for forming the coating layer of the present invention, it is preferable that the content of inevitable impurities is as low as possible except for Ni which is an essential element and the remaining Mo in order to ensure oxidation resistance. As the inevitable impurities, inevitable impurities such as oxygen, nitrogen, carbon, Fe, Cu, Al, Si and the like may be included as long as the effects of the present invention are not impaired. For example, oxygen and nitrogen of the gas components are each preferably 1000 ppm by mass or less, carbon, Fe, and Cu are each 200 ppm by mass or less, and Al and Si are each 100 ppm by mass or less. It is preferable that it is 9 mass% or more.

First, a sputtering target for forming a Mo—Ni alloy film to be a coating layer was produced.
Target materials having Mo-15 atomic% Ni and 30 atomic% Ni compositions were prepared by powder metallurgy. Mo powder with an average particle size of 6 μm and Ni powder with an average particle size of 100 μm are mixed so as to be Mo-15 atomic% Ni and Mo-30 atomic% Ni, filled in a can made of mild steel, and then heated. Evacuated and sealed. Next, the sealed can was put into a hot isostatic press and sintered under conditions of 1100 ° C., 100 MPa, 3 hours, and then Mo-15 atomic% Ni having a diameter of 100 mm × 5 mm in thickness by machining. A Mo-30 atomic% Ni alloy target material was obtained. Moreover, the pure Mo target material was obtained by the same method as described above.
A target material having a Mo-80 atomic% Ni composition was prepared by a melting method. Electrolytic Ni and massive Mo raw material are weighed to a predetermined amount, then melted in a vacuum induction heating furnace to produce an ingot, stretched into a plate shape by plastic working, and then Mo-80 atomic% Ni alloy alloy by machining. -A get material was prepared.

Each target material obtained above was brazed to a Cu backing plate and attached to a sputtering apparatus. Note that SPF-440H manufactured by Canon Anelva Co., Ltd. was used as the sputtering apparatus.
The coating layer shown in Table 1 was formed with a thickness of 30 nm on a glass substrate of 25 mm × 50 mm. For the formation of the coating layer, the pure Mo, Mo-15 atomic% Ni, and Mo-30 atomic% Ni obtained above were formed by sputtering using a target having the same composition as the coating layer. For the other coating layers, using a co-sputtering film forming method in which pure Mo and a Mo-80 atomic% Ni target are sputtered simultaneously, the power at that time is changed, and the Mo-Ni alloy coating shown in Table 1 is applied. A layer was formed.
The produced coating layers were analyzed by ICP (dielectric plasma emission analyzer) of ICPV-1017 manufactured by Shimadzu Corporation, and the components of each coating layer were confirmed.
Next, a main conductive layer made of Cu having a thickness of 300 nm is formed by sputtering on the coating layer formed on the glass substrate obtained above, and then the coating layers shown in Table 1 are described above on the main conductive layer. The laminated wiring film was obtained by the co-sputtering film forming method. For comparison, a Mo-10 atomic% Nb alloy film was also produced.

The degree of oxidation of each sample in which the laminated wiring film shown in Table 1 was formed on a glass substrate was evaluated by the reflectance after heating at 250 ° C. and 350 ° C. for 1 hour in the air. The reflectance was measured from the upper coating layer side in the visible light region using a spectrocolorimeter CM-2500d manufactured by Konica Minolta.
Moreover, the change of the electrical resistance value of each sample was also evaluated. The electrical resistance value was measured using a 4-terminal thin film resistivity meter MCP-T400 manufactured by Dia Instruments Co., Ltd. The results are shown in Table 1.

As shown in Table 1, when a laminated wiring film in which Cu is coated with a Mo-based alloy is heated in the atmosphere, the electric resistance value is almost the same as that during film formation up to 250 ° C. However, when heated to 350 ° C., the multilayer wiring film using the Mo coating layer of the comparative example and the Mo-10 atomic% Nb coating layer has a significant decrease in reflectance and a large increase in electrical resistance. Recognize. This is presumably because the surface of the coating layer is oxidized, and the transmitted oxygen reaches the Cu of the main conductive layer and the main conductive layer is also oxidized.
In addition, it was confirmed that the electrical resistance value when heated at a temperature of 350 ° C. significantly increased when the Ni addition amount of the coating layer was less than 10 atomic%, which is outside the range of the present invention.
On the other hand, the laminated wiring film using the coating layer obtained by adding a specific amount of Ni to Mo of the present invention example suppresses a decrease in reflectance and an increase in electric resistance even when heated to 350 ° C. It can be seen that the chemical property is improved. Addition of 20 to 50 atomic% Ni, which is a preferable range in the present invention, further suppresses a decrease in reflectivity and an increase in electric resistance value, and confirms that this is a multilayer wiring film suitable for electronic components.

Similarly to Example 1, a Mo—Ni alloy film serving as a coating layer having the structure shown in Table 2 was formed on a 25 mm × 50 mm glass substrate by sputtering, and then, Cu having a thickness of 200 nm was formed on the coating layer. The main conductive layer to be formed was formed by a sputtering method to produce a multilayer wiring film for electronic parts.
Each sample shown in Table 2 was evaluated for changes in reflectance and electrical resistance value from the main conductive layer side after heating at 350 ° C. and 450 ° C. for 1 hour in a vacuum of 0.1 Pa or less. The vacuum heating can also confirm a characteristic change due to element diffusion without considering a characteristic change due to oxidation. The same measuring apparatus as in Example 1 was used for both reflectance and electrical resistance. The results are shown in Table 2.

As shown in Table 2, the laminated wiring film in which the main conductive layer made of Cu is formed on the coating layer made of the Mo—Ni alloy to which Ni is added within the scope of the present invention is reflected in a vacuum of 0.1 Pa or less. It can be seen that there is little decrease in rate and increase in electrical resistance. In the present invention, when 20 to 50 atomic% of Ni in a preferable range was added, the decrease in reflectance and the increase in electric resistance value were further suppressed, and it was confirmed that the laminated wiring film was suitable for electronic parts.
In addition, even when heated in a vacuum atmosphere where the progress of oxidation can be suppressed, if the Ni addition amount of the coating layer exceeds 65%, the reflectivity decreases at 450 ° C. and the electrical resistance value also increases. I understand. This is presumably because Ni in the Mo—Ni alloy of the coating layer partially diffuses into the Cu of the main conductive layer, the Cu film surface unevenness increases, the metallic luster is lost and the color changes. . However, the heating condition of 450 ° C. set above is a special condition, and in general electronic parts, heating up to about 350 ° C. is performed. No. The electrical resistance value indicated by 8 can be used as a laminated wiring film for electronic parts.

  A laminated film of Mo—Ni alloy or Mo and Cu as the main conductive layer is formed on a 25 mm × 50 mm glass substrate by a sputtering method in the same manner as in Example 1, and a wiring film for electronic components is formed. Produced. The thickness of the Cu film as the main conductive layer was set to 300 nm, and the thickness of the upper coating layer was changed to produce each sample having the configuration shown in Table 3. In the same manner as in Example 1, each sample was subjected to heat treatment at 150, 250, and 350 ° C. for 1 hour in the atmosphere, and the electrical resistance value and the change in reflectance from the upper coating layer side were measured. The results are shown in Table 3.

As shown in Table 3, the sample No. of Cu film having no coating layer as a comparative example was used. 1 and Sample No. with a coating layer of Mo. 2-Sample No. 2 When the laminated wiring film whose thickness of the coating layer is changed in 3 is heated in the atmosphere, the color changes from 150 ° C., the reflectance decreases, the electrical resistance value increases, and the electrical resistance value increases more than 250 ° C. Increase was confirmed. Moreover, when it coat | covered with Mo, when the film thickness of Mo was 10 nm, it was confirmed that a reflectance falls from 150 degreeC and an electrical resistance value increases large at 250 degreeC. Moreover, when the film thickness of Mo becomes as thick as 30 nm and 50 nm, a decrease in reflectance and an increase in electrical resistance value are suppressed. However, it has been confirmed that even if the coating layer is formed to have a thickness of 50 nm, a decrease in reflectance and an increase in electrical resistance cannot be suppressed at a high temperature of 350 ° C.
On the other hand, the laminated wiring film using the Mo—Ni alloy of the present invention as a coating layer has a high effect of suppressing a decrease in reflectance and an increase in electric resistance value from a film thickness of 10 nm. The increase in electrical resistance value could be suppressed to a high temperature of 350 ° C. Further, the resistance value of the laminated wiring film increases as the thickness of the coating layer increases, but a low electrical resistance value of 4.0 μΩcm or less can be maintained even at 150 nm. As described above, according to the present invention, it was possible to prevent the oxidation of Cu, which is the main conductive layer, and to confirm that it was useful as a laminated wiring film for electronic parts.

Claims (4)

A laminated wiring film for an electronic component in which a metal film is formed on a substrate, comprising a main conductive layer made of Cu and a coating layer covering one surface and / or the other surface of the main conductive layer, the coating layer being an atomic layer A laminated wiring film for an electronic component, wherein the composition formula in the ratio is represented by Mo _100-X Ni _X , 10 ≦ X ≦ 70, and the balance is a Mo—Ni alloy composed of inevitable impurities.   2. The multilayer wiring film for an electronic component according to claim 1, wherein X in the composition formula is 20 to 50. 3.   The multilayer wiring film for an electronic component according to claim 1 or 2, wherein the coating layer has a thickness of 10 to 200 nm.   The multilayer wiring film for an electronic component according to any one of claims 1 to 3, wherein a thickness of the main conductive layer is 100 to 500 nm.