JP2008263191A - Metal thin-film wiring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal thin-film wiring containing a base film or a cover film wherein adhesiveness is secured and elevation of resistance value is inhibited. <P>SOLUTION: The metal thin-film wiring is constituted by laminating a Mo alloy film wherein Ti is contained by 2-50 at.% and the remaining portion is comprised of Mo and unavoidable impurities, as a base film of an Ag film, a Cu film, an Au film or an alloy film containing them as a main constituent. The metal thin-film wiring is constituted by laminating the Mo alloy film wherein the Ti is contained by 2-50 at.% and the remaining portion is comprised of Mo and unavoidable impurities, as a cover film of the Ag film, the Cu film, the Au film or the alloy film containing them as a main constituent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a metal thin film wiring used for electrical wiring, electrodes and the like of thin film electronic components such as liquid crystal displays, thin film sensors, and magnetic heads.

  In recent years, low resistance Al, Cu, and Ag have been used for electric wiring films used for thin film transistor type liquid crystal displays (TFT-LCDs) for forming thin film devices on glass substrates and thin film sensors for forming elements on ceramic substrates. Further, pure metal films such as Au or alloy films mainly composed of them have been used. In general, these films are inferior in any of heat resistance, corrosion resistance, and adhesion required as an electric wiring film, and thus have a problem that they cannot sufficiently withstand the process for forming the electric wiring.

Therefore, in order to solve the above problems, it is considered to form a thin film such as Cr, Mo, Ti, which is a refractory metal, as a base film or a cover film for the substrate, among which heat resistance, corrosion resistance, Mo and Mo alloys have been widely used from the viewpoints of adhesion, cost, and environmental conservation. For example, in a liquid crystal display device, an alloy film in which Cr, Ti, Ta, and Nb are added to Mo has been proposed as a Mo alloy film to be laminated with an Al wiring (see, for example, Patent Document 1).
JP 2000-284326 A

  Although the above-mentioned Mo alloy film is described as being excellent in heat resistance and etching property as a laminated film with Al wiring, Ag film, Cu film, Au film having lower resistance than Al, or an alloy mainly composed of these There are no disclosures about Mo alloys having excellent properties as adhesion films, underlayers that suppress the increase in resistance of Ag films, Cu films, Au films or alloy films mainly composed of these films, and cover films. Not.

  In view of the above problems, an object of the present invention is to provide a metal thin film wiring having a base film or a cover film that secures adhesion and suppresses an increase in resistance value.

  The present inventor added various additive elements to Mo in order to search for a Mo alloy film desirable as a base film or a cover film laminated on an Ag film, a Cu film, an Au film, or an alloy film mainly composed of these films. A Mo alloy target was prepared, a Mo alloy film was systematically formed by sputtering, and it was found that a Mo—Ti alloy was desirable, leading to the present invention.

That is, according to the present invention, an Ag alloy film, a Cu film, an Au film, or an alloy film mainly composed of these is laminated with a Mo alloy film containing 2 to 50 atomic% of Ti and the balance of Mo and inevitable impurities. This is a metal thin film wiring formed.
In addition, the present invention provides a cover film of an Ag film, a Cu film, an Au film, or an alloy film mainly composed of these films, in which a Mo alloy film containing 2 to 50 atomic% of Ti, the balance being Mo and inevitable impurities is laminated. This is a metal thin film wiring formed.

  As described above, according to the present invention, it is possible to obtain a metal thin film wiring in which a Mo alloy film excellent in corrosion resistance and further having excellent adhesion with an Ag film, a Cu film, an Au film or an alloy film mainly composed of these is laminated. Therefore, it is used for electrical wiring, electrodes, etc. of thin film electronic components and has high industrial utility value.

  The Mo alloy film of the present invention is a Mo alloy film containing Ti mainly composed of Mo, does not contain harmful Cr, and has high heat resistance, corrosion resistance and adhesion as a base film such as Ag or an Ag alloy film. A metal thin film can be obtained.

  The reason for selecting Ti as an element to be added to Mo is that it has an effect of improving the corrosion resistance of Mo. Further, since Ti is an element having a solid solution region for both Ag and Mo, adhesion is improved by adding Ti to Mo as a base film or a cover film for a low-resistance Ag or Ag alloy film. Furthermore, it is because the effect of suppressing an increase in the resistance value of Ag or an Ag alloy film is high by reducing the misfit of the crystal lattice.

Here, the addition amount of Ti is desirably 2 to 50 atomic%. If it is less than 2 atomic%, the effect of improving the corrosion resistance of the formed film is low, and if it exceeds 50 atomic%, the etching property is lowered. Further, it is desirable that the amount of Ti added be 10% or more in order to sufficiently match the lattice of Ag and Ag alloy film. This is because the crystal lattice misfit with Ag becomes as large as 5% or more at 10% or less.
Ti, like Ag, also has a solid solution region with Cu and Au common as group Ib elements. For this reason, the Mo—Ti alloy film in which Ti is added to Mo also improves the adhesion with an alloy film mainly composed of Cu, Au, Cu, and Au. Therefore, these films are used as a base film and a cover film for these films. It is possible.

  As described above, the composition of the film formed by sputtering has a strong correlation with the target composition, and by using the target having the above composition, it is possible to form a film having the same composition and excellent in various characteristics. A metal film is obtained.

  The Mo alloy thin film of the present invention preferably contains as few impurities as possible in order to improve and stabilize the characteristics of the film obtained by sputtering. Specifically, it is preferable that the sum of Mo and Ti has a purity of 99.9% by mass or more in a content ratio excluding gas components. In addition, it is desirable that Fe as a transition metal is 300 ppm or less, Ni is 200 ppm or less, Na, K, and Ca as alkali metals are 5 ppm or less, and U and Th as radioactive elements are each 1 ppm or less.

  In particular, when the Mo alloy film of the present invention is used in a thin film transistor-driven liquid crystal display using amorphous Si, which is the mainstream at present, and high-definition low-temperature polycrystalline Si, it causes junction leakage of these semiconductor elements. Reduction of transition metals is effective, and Fe is preferably 300 ppm or less, Ni is 200 ppm or less, and further preferably 50 ppm or less. It is also effective to reduce radioactive elements that emit α-rays and cause malfunction of the semiconductor element, and it is desirable that U and Th be 1 ppm or less, and further 0.1 ppm or less. In addition, the above-described purity excluding gas components is also preferably 99.9% or more, and more preferably 99.99% or more.

  Furthermore, in order to further improve and stabilize the characteristics of the Mo alloy film obtained by sputtering of the present invention, the O (oxygen) content, which is a gas component involved in the film characteristics, is 1000 ppm or less, and the C (carbon) content. Is preferably 500 ppm or less. When O becomes 1000 ppm or more, the resistance value and the film stress increase, and the etching property is affected. For this reason, it goes without saying that the O content is preferably 1000 ppm or less, more preferably 300 ppm or less, and even more preferably 100 ppm or less. Similarly, the film characteristics can be further stabilized by setting the C content to 500 ppm or less, and further to 50 ppm or less.

Next, specific examples of the present invention will be described.
First, pure metal and Mo alloy target were manufactured by the various manufacturing methods described below.
[Production method A]
A method of manufacturing an ingot having a diameter of 150 mm using an electron beam melting apparatus having an ultimate pressure of 3 × 10 ⁻³ Pa, cutting and manufacturing a target (AE), producing an ingot having a diameter of 100 mm by plasma melting, Similarly, the manufacturing method is (AP).
[Production method B]
In this method, powders are mixed and sintered so as to have a predetermined composition. Among them, a method of inserting into a carbon mold and cutting out from a sintered body manufactured by hot pressing is referred to as (BP). The surface pressure of the hot press was 30 MPa, and the temperature was 1300 ° C. for the Mo alloy. On the other hand, a method of encapsulating in a mild steel capsule and cutting out from a sintered body manufactured by HIP treatment is (BH). In the Mo alloy, the HIP treatment pressure was 120 MPa, and the heating temperature was 1000 ° C. Further, a method of sintering a powder that has been formed into a pressure-formed body by cold isostatic pressing (CIP) is referred to as (BS). In the sintering, a hydrogen sintering furnace was used and the heating temperature was 1700 ° C.

Further, in the above-described production methods A and B, (R) is used as a subscript for the method of performing forging and rolling plastic working on the ingot or sintered body produced by the melting method. During the plastic working, the material was heated to improve workability, and the temperatures were set to 1200 ° C., 1000 ° C., 600 ° C. for Cr, Mo, and Ti, and 800 to 1000 ° C. for the Mo alloy. The material was enclosed in a capsule and plastic processing was performed.
A plate-like target material was produced by the various production methods described above, and a target having a predetermined size was produced by machining.

  Targets having the compositions shown in Table 1 were produced by various production methods, attached to a sputtering apparatus, and formed to a thickness of 20 nm on a glass substrate. After formation, the film was immersed in pure water at a temperature of 80 ° C. for 30 minutes, and then the presence or absence of discoloration on the film surface was confirmed to evaluate corrosion resistance. Similarly, a 40 nm-thick film having a thickness of 40 nm was used as a base film, and an Ag—Zr—Cu alloy film was formed to 200 nm thereon. Thereafter, a scotch tape was attached on the Ag alloy film and peeled off at an angle of 45 ° C. to evaluate the adhesion with the Ag alloy film. The case where the film was completely peeled off was rated as x, the case where part of the film was peeled off was rated as Δ, the case where the film was not peeled but had defects was marked as ○, and the case where no film was peeled off was marked as ◎.

  When the corrosion resistance was evaluated, the pure Mo film and the pure Ti film were discolored, and the Mo-60Ti alloy film having a Ti content exceeding 50 atomic% was also discolored. The alloy film did not change color. Therefore, it can be seen that the pure Cr film and the Mo—Ti alloy film of the present invention have good corrosion resistance. The adhesion with the Ag alloy is that of sample No. 3 pure Ti film is preferable. It can also be seen that the Mo alloy is a Mo—Ti alloy film containing 2 atomic% or more of Ti and has good adhesion. From the above, it can be seen that the base film having good corrosion resistance and adhesion to the Ag alloy is a Mo—Ti alloy, and its addition amount is 2 to 50 atomic%.

Claims (2)

As a base film for an Ag film, a Cu film, an Au film, or an alloy film mainly composed of these films, a Mo alloy film containing 2 to 50 atomic percent of Ti, and the balance of Mo and inevitable impurities is laminated. Metal thin film wiring. As a cover film for an Ag film, a Cu film, an Au film, or an alloy film mainly composed of these films, a Mo alloy film containing 2 to 50 atomic% of Ti and the balance of Mo and inevitable impurities is laminated. Metal thin film wiring.