JPH03129326A - Wiring structure and wiring method for semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the oxidation at junctures by the oxygen contained in a transparent oxide electrode at the time of a heat treatment and to prevent the generation of the conduction failure defect arising from the insulator formed by oxidation by adopting the wiring structure in which the transparent oxide electrodes and an oxidation resistant conductive film are connected. CONSTITUTION:The wiring structure of the semiconductor device in which the transparent oxide electrode 103 and the oxidation resistant conductive film 102 are connected is adopted. Any of indium tin oxide (ITO), indium oxide, tin oxide, zinc oxide, and zinc aluminum oxide is used as the transparent oxide electrode 103 and the metal silicide of any among platinum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, and palladium is used as the oxidation resistant conductive film 102. The oxidation of the conductive film by the oxygen contained in the oxide constituting the transparent electrode at the time of a heat treatment does not arise at the boundary of the juncture between the transparent oxide electrode and the oxidation resistant conductive film and the conduction failure arising from the insulator formed by the oxidation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wiring structure and wiring method for a semiconductor device in which an oxide transparent electrode and an oxidation-resistant conductive film are connected.

[Conventional technology]

In recent years, liquid crystal displays (hereinafter abbreviated as LCD) in which thin film transistors (hereinafter abbreviated as TPT) are formed on an insulating substrate such as glass have been attracting attention as a favorite among flat panel displays. A wiring structure generally used as a lead-out portion of a common electrode that also serves as a lower electrode of one pixel of a liquid crystal and a charge holding capacitor section will be described with reference to FIG. The LCD shown in FIG. 9 is classified into three blocks: a switching TFT section 914, a charge holding capacitor section 915, and a common electrode lead-out section 91.
It becomes 6. The switching TFT section 914 includes a polycrystalline silicon film (channel section) on a transparent substrate 901 made of glass or the like.
902, a gate oxide film 903, and a gate electrode 904 are sequentially formed, and a source region 905 and a drain region 906 made of a polycrystalline silicon film doped with impurities are also formed adjacent to the polycrystalline silicon film 902 on the transparent substrate 901. , a source electrode 9 made of AQ is provided in the source region 905.
09 is connected to the drain region 906, and a drain electrode 912 made of AQ is connected to the drain region 906. The charge retention capacitor section 915 is used to compensate for unevenness in image display caused by changes in TPT off-state current over time and a decrease in LCD resistance, etc., and to obtain good image quality. A common electrode 907 that also serves as the lower electrode of a charge retention capacitor made of an ITO film (hereinafter abbreviated as ITO) is formed, and a pixel electrode 911 made of an ITO film forms the capacitor via a dielectric. . The common electrode lead-out portion 916 has a common lead-out lower electrode 913 formed on the transparent substrate 901 and connected to the common electrode 907, and the upper part thereof is connected to the common lead-out electrode 910. The pixel electrode 911 made of ITO film is the drain electrode 9 made of AM.
A common electrode 90 connected to 12 and also made of an ITO film
7 is connected to a lower common lead-out pole 913 made of An. However, ITO and AQ react with each other at the contact forming part, which is the connection surface, and an oxide AQ□O1 of AQ, which is an insulator, is formed at the interface, making it impossible to obtain ohmic contact characteristics and reducing the reliability of the contact forming part. There was a problem. In addition, it was reported in the literature, 49th Japan Society of Applied Physics Proceedings, p. 409 (1988, Autumn), that the above reaction occurs significantly even in a heat treatment process at a relatively low temperature of about 300"C, and the contact resistance increases significantly. However, in the LCD forming process, which undergoes various low-temperature heat treatments at about 400° C. after contact formation, there is a problem of poor yield due to the above-mentioned conduction defects.

In order to solve the above problem, Japanese Patent Laid-Open No. 58-190063 proposes a method in which a doped polycrystalline silicon film serving as a drain region is directly connected to a pixel electrode made of ITO. However, polycrystalline silicon film and IT
Even in the case of connecting O, there is a phenomenon in the literature, i.
EE Electron Device Letters, pp. 134-136, EDL-7, No. 2, 1986
(I E E E P E 1ectron Dev
iceLetters, p134-136. Vol.E
D L-7, No. 2.1986). As described above, in the prior art, a structure that provides good contact characteristics with ITO has not been realized.

The above problem is not limited to ITO, but tin oxide (S) is used as a transparent electrode.
n OW , indium oxide (In, ○,);

Zinc oxide (ZnO), zinc oxide/aluminum (Zn
The problem is the same when using various oxide films of OA n), and it is a problem not only for LCDs but also for semiconductors with transparent electrodes and wiring in various flat panel displays such as electroluminescent displays and solar cells. It became.

[Problem to be solved by the invention]

In the above conventional technology, when a transparent electrode made of various oxide films such as ITO is contacted with a wiring made of a metal such as AFL or a doped polycrystalline silicon film, the metal or polycrystalline silicon film becomes an oxide at the interface of the contact. No consideration was given to the fact that insulating metal oxides are produced by oxidation by the oxygen contained therein, resulting in defects such as poor contact, and the above-mentioned defects occur during heat treatment, resulting in poor product yields.

An object of the present invention is to solve the above-mentioned problems and to provide a wiring structure of a connection part that has ohmic connection characteristics with a transparent electrode and excellent heat resistance, and a method for forming the same.

[Means to solve the problem]

The above object is achieved by providing a wiring structure for a semiconductor device in which an oxide transparent electrode and an oxidation-resistant conductive film are connected.

The above object is achieved by providing a wiring structure for a semiconductor device in which an oxide transparent electrode and a metal wiring are connected via an oxidation-resistant conductive film.

The above object is achieved by providing a wiring structure for a semiconductor device in which a transparent oxide electrode and a wiring made of an oxidation-resistant conductive film are connected.

The above object is achieved by providing a wiring structure for a semiconductor device in which an oxide transparent electrode and a wiring made of a silicon film doped with impurities are connected via an oxidation-resistant conductive film.

The above object is achieved by providing an arrangement IjlA structure for a semiconductor device in which an oxide transparent electrode and a wiring made of a silicon film doped with impurities are connected via a silicide film.

The above purpose is to use platinum as the oxidation-resistant conductive film.

This is achieved by providing a wiring W structure for a semiconductor device using a metal silicide of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, or palladium.

The above purpose is to improve the oxidation resistance f! ! This can be achieved by providing a wiring structure for a semiconductor device using at least one of chromium, titanium, and nitride thereof as a film.

The above object is achieved by providing a wiring structure for a semiconductor device using any one of indium oxide 1 lil (ITO), indium oxide, Wi tin oxide, zinc oxide, and zinc oxide aluminum as the oxide transparent electrode. be done.

The above object is achieved by providing a wiring method for a semiconductor device that connects an oxide transparent electrode and an oxidation-resistant conductive film.

[Effect]

According to the above configuration, the oxidation-resistant conductive film, for example, platinum silicide, is not oxidized due to its physical properties as a noble metal, and heat treatment is performed at the connection interface between the oxide transparent electrode and the oxidation-resistant conductive film. At times, the oxidation-resistant conductive film is not oxidized by oxygen contained in the oxide that constitutes the transparent electrode.

There is no occurrence of conduction defects caused by insulators produced by oxidation.

Even if metals other than silicide, such as chromium and titanium, and their nitrides are used as the oxidation-resistant conductive film, they will not be oxidized due to the same effect.

By adopting such a wiring structure, it is possible to provide a semiconductor device having a connection portion between a transparent electrode and a wiring, which has excellent heat resistance and reduces conduction failure defects that occur during heat treatment.

〔Example〕

Examples of the present invention will be described using figures and tables.

Figures 1a to 1c are examples of contacts using indium tin oxide (ITO) as the transparent electrode and platinum silicide as the oxidation-resistant conductive film, connecting wiring made of ITO and metals such as AQ through the silicide. FIG. 2 is a sectional view showing the basic structure of a contact.

FIG. 1a shows a first arrangement A in which a pad electrode 102 made of a silicide film, such as platinum silicide film, for forming a contact portion is formed on an insulating substrate 101 made of glass or the like and made of ITO.
! 103, and AQ is formed on the pad electrode 102.
2 is a sectional view showing a cross section of a structure in which a second wiring 105 made of a metal such as, etc. is connected, and a first wiring 103 and a pad electrode 102 are covered with an interlayer insulating film 104 made of, for example, Sin.

In other words, the first wiring 103 and the second wiring 105 are connected via the pad electrode 102 made of silicide. Therefore, the connection between the first wiring 103 made of ITO and the pad electrode 102 made of silicide has good contact characteristics with excellent heat resistance, and the connection between the pad electrode 102 made of silicide and the second wiring made of metal such as AQ can be achieved. The contact characteristics with 105 are r': ohmic without any problem.

FIG. 1b is a cross-sectional view showing a configuration in which the metals such as ITO and Al1 are exchanged in each wiring in FIG. 1a, in which the first wiring 106 is made of metal such as AQ,
An example of using ITO in 1107, ITO and silicide 10
The contact characteristics of 8 are no different from those of FIG. 1a.

FIG. 1c is a sectional view showing a cross section of a structure in which a first wiring 110 made of a metal such as Aλ and a second wiring 111- made of ITO are connected via a pad electrode 109 made of silicide. If the resistance of the wiring material itself is a problem because it has a higher specific resistance than metal, it is effective to shorten the ITO portion by replacing it with metal via silicide, thereby reducing the resistance value. In addition to platinum, a silicide of a highly oxidation-resistant metal such as titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, or palladium can also be used. Effects can be obtained. The silicide film may be formed using a metal-silicon direct reaction (silicidation reaction) or a sputtering method.

FIG. 2 is a sectional view in which the structure shown in FIG. 1a is actually applied to a common electrode extension portion that also serves as a lower electrode of a charge retention capacitor of an LCD.

A common electrode 207 made of ITO is connected to a common lead-out lower electrode 213 made of a platinum silicide film on an insulating substrate 201 such as glass to form a contact part,
A common extraction electrode 210 made of metal such as Afi is connected to the common extraction lower electrode 213 .

3a to 3b are cross-sectional views showing the basic structure of a contact in which wiring made of ITO and a silicon film doped with impurities are connected via silicide.

FIG. 3a shows a first wiring 302 and a first wiring 30 made of a doped silicon film on an insulating substrate 301 such as glass.
Contact portion 3 formed by siliciding a part of 2
3 is a cross-sectional view showing a cross section of a structure in which a contact portion 303 is formed and a second wiring 305 made of ITO is connected to a contact portion 303. First wiring 302 and contact portion 3
03 is covered with an interlayer insulating film 304. Since the contact portion 303, which is a part of the first wiring 302 that connects to the second wiring 305 made of ITO, is made of silicide,
Good contact characteristics can be obtained.

FIG. 3b is a sectional view showing a cross section of a structure in which a first wiring 306 made of a doped silicon film and a second wiring 308 made of TOO are connected via a silicide portion 307. When the resistance of the wiring material itself becomes large due to its large specific resistance, it is effective to shorten the ITO portion by replacing it with a doped silicon film via silicide, thereby reducing the resistance value.

FIG. 4 is a cross-sectional view of a structure in which the drain electrode 406 of the LCD shown in FIG. 3a and a pixel electrode 411 made of ITO are actually connected via a contact portion 407 made by siliciding a part of the drain electrode 406. It is. Figure 3a,
In FIGS. 3b and 4, a part of the first wiring 302 made of a silicon film doped with impurities is silicided to form a silicide film in the contact portion, but in FIG.
The silicide film may be formed by sputtering as shown in FIGS. 1B, 1C, and 2.

FIG. 5a is a cross-sectional view showing the structure of a contact when the silicide used for connection with ITO is directly used as a wiring. A wiring 502 made of silicide is formed on an insulating substrate 501 such as glass, and an electrode 50 made of ITO is formed.
4 are connected and covered with an interlayer insulating film 503.

FIG. 5b is also a sectional view showing the structure of a contact when the silicide used for connection with ITO is used as is as a wiring. A first wiring 505 made of silicide is formed on an insulating substrate 501 made of glass or the like, and a second wiring 506 made of ITO is connected. Figures 5a and 5
Since the contact portion shown in Figure b is made of silicide and TTO, it goes without saying that the contact characteristics are good.

Next, the contact characteristics of a contact connecting ITO as a transparent electrode and silicide as an oxidation-resistant conductive film will be described in detail.

FIGS. 6a to 6c are charts regarding the contact characteristics of TO and conventional materials and silicides discovered by the inventors.

FIG. 6a shows the current flowing through a conventional ITO-metal AQ contact when a voltage is applied thereto. Irregular current changes indicate an unstable state at the contact interface.

FIG. 6b shows the current flowing through a conventional ITO and n''Si contact when a voltage is applied thereto. The nonlinear increase in current indicates that the contact interface is not in a normal state.

Figure 6c shows the current flowing through the ITO and silicide contacts when a voltage is applied thereto.

A current that increases linearly with an increase in voltage indicates that the contact interface is normal and ohmic contact characteristics are obtained.

FIG. 7 is a chart showing the relationship between heat treatment temperature and contact resistance in contact structures between ITO, conventional materials, and silicide. Conventional ITO and metal AQ contact (a
) and the contact between ITO and n+Si (b) at 200°C.
It already shows a contact resistance value of io-"cΩ・aI) at a low-temperature heat treatment temperature of .

The contact resistance value increases significantly at a heat treatment temperature of 450°C. On the other hand, the contact between ITO and silicide (c) is 45
No increase in contact resistance was observed at a heat treatment temperature of 0°C;
The heat resistance during heat treatment at 50°C or lower is extremely excellent.

Figure 8 shows the current that flows when a voltage is applied to the ITO and silicide (platinum silicide) contact after heat treatment at 450°C, and the contact characteristics are as ohmic as before heat treatment. It is shown that.

The above example uses ITO (indium tin oxide) as the transparent electrode, but the same applies to cases where other oxide transparent electrodes such as indium oxide, tin oxide, zinc oxide, or zinc oxide/aluminum are used. The effect of this can be obtained.

Further, although an example in which silicide is used as the oxidation-resistant conductive film has been described, similar effects can be obtained by using other oxidation-resistant conductive films such as metals such as chromium and titanium and their nitrides.

Furthermore, although the wiring structure of an LCD has been described as an application example of the present invention, the present invention can also be applied to various flat displays such as EL displays and semiconductor devices including transparent electrode wiring such as solar cells.

〔Effect of the invention〕

According to the present invention, by forming a wiring structure in which an oxide transparent electrode and an oxidation-resistant conductive film are connected, the oxidation-resistant conductive film, due to its oxidation resistance, allows the oxide to form at the interface of the connection part during heat treatment. It is not oxidized by the oxygen contained in the transparent electrode, and there is no occurrence of conduction defects caused by insulators generated by oxidation.Therefore, problems in the heat treatment process are solved and semiconductor devices can be manufactured with a high yield. .

[Brief explanation of the drawing]

1a, 1b, 1c, 2, 3a, 3b, 4, 5a, and 5b are cross-sectional views showing the structure of contacts according to embodiments of the present invention. , Figure 6a, 6th
Figure b is a chart showing the relationship between applied voltage and current in a conventional contact, Figure 6c is a chart showing the relationship between applied voltage and current in a contact according to an embodiment of the present invention before heat treatment, and Figure 7 is a chart showing the relationship between applied voltage and current in a contact according to an embodiment of the present invention. A chart showing the relationship between heat treatment temperature and contact resistance of the contact according to the embodiment of the invention and a conventional contact, and FIG. 8 shows the relationship between applied voltage and current after heat treatment of the contact according to the embodiment of the present invention. Chart, No. 9
The figure is a sectional view showing the structure of a conventional LCD. 101... Insulating substrate, 102... Pad electrode made of platinum silicide film, 1
03...First wiring made of ITO. 104... Interlayer insulating film, 105... Second wiring made of metal. 106...10 in the first wiring using metal such as AQ
7... Second wiring using ITO, 10g... Pad electrode made of platinum silicide film, 109... Pad electrode made of platinum silicide. 110...First wiring made of metal such as AQ.

Claims (1)

[Claims] 1. A wiring structure for a semiconductor device, characterized in that an oxide transparent electrode and an oxidation-resistant conductive film are connected. 2. A wiring structure for a semiconductor device, characterized in that an oxide transparent electrode and a metal wiring are connected via an oxidation-resistant conductive film. 3. A wiring structure for a semiconductor device, characterized in that a transparent oxide electrode and a wiring made of an oxidation-resistant conductive film are connected. 4. A wiring structure for a semiconductor device, characterized in that an oxide transparent electrode and a wiring made of a silicon film doped with impurities are connected via an oxidation-resistant conductive film. 5. A wiring structure for a semiconductor device, characterized in that an oxide transparent electrode and a wiring made of a silicon film doped with impurities are connected via a silicide film. 6. As the oxidation-resistant conductive film, platinum, titanium, zirconium, hafnium, vanadium, niobium, tantalum,
5. The wiring structure of a semiconductor device according to claim 1, wherein a metal silicide selected from chromium, molybdenum, tungsten, cobalt, nickel, and palladium is used. 7. The wiring structure of a semiconductor device according to any one of claims 1 to 4, wherein at least one of chromium, titanium, or a nitride thereof is used as the oxidation-resistant conductive film. . 8. As the oxide transparent electrode, indium tin oxide,
6. The wiring structure of a semiconductor device according to claim 1, wherein any one of indium oxide, tin oxide, zinc oxide, and zinc oxide/aluminum is used. 9. A semiconductor device using the wiring structure according to any one of claims 1 to 8. 10. A liquid crystal display characterized by using the wiring structure according to any one of claims 1 to 8. 11. The liquid crystal display according to claim 10, wherein the wiring structure is a lower electrode extension portion of a charge retention capacitor made of a transparent electrode. 12. The liquid crystal display according to claim 10, wherein the wiring structure is a connecting portion between a pixel electrode and a drain electrode, each of which is a transparent electrode. 13. An electroluminescent display characterized by using the wiring structure according to any one of claims 1 to 8. 14. A solar cell characterized by using the wiring structure according to any one of claims 1 to 8. 15. A semiconductor device wiring method for connecting an oxide transparent electrode and an oxidation-resistant conductive film.