JP2003338465A - Mo-W TARGET FOR FORMING WIRING, Mo-W WIRING THIN FILM USING THE SAME, AND LIQUID-CRYSTAL DISPLAY DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a target for forming wiring, together with a wiring thin film using the same, which is made from a wiring forming material of high resistance against an etchant such as an interlayer insulating film and ITO low in resistance and tapered, at forming of the wiring with a liquid-crystal display device, etc. <P>SOLUTION: An Mo-W target for forming wiring is made from an Mo-W alloy which contains tungsten by 20-95 atom.% and molybdenum and inevitable impurities for the remaining part. The Mo-W alloy has a relative density of 98% or higher, and an average particle size of crystal grain is 200 μm or less and has a metal composition of solid solution phase of Mo and W. An Mo-W wiring thin film is formed with the Mo-W target for forming wiring. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring forming Mo-
The present invention relates to a W target, a Mo-W wiring thin film using the W target, and a liquid crystal display device.

[0002]

2. Description of the Related Art Recently, amorphous silicon (hereinafter referred to as "a-S
Attention has been focused on an active matrix type liquid crystal display device in which a thin film transistor (hereinafter referred to as “TFT”) formed by using a film described as “i”) is applied as a switching element. This is a large-area, high-definition, high-quality and inexpensive panel display, that is, a flat-type television, by forming a TFT array using an a-Si film that can be formed at low temperature on an inexpensive glass substrate. Is possible.

However, in the case of constructing a large-area display, the total length of the address wiring inevitably increases dramatically, and the resistance of the address wiring increases. With the increase of the resistance of the address wiring, the delay of the gate pulse given to the switch element becomes remarkable, which causes a problem that the control of the liquid crystal becomes difficult. Therefore, it is necessary to avoid the delay of the gate pulse while maintaining at least the parameters such as the wiring width.

As one means for avoiding the delay of the gate pulse, it is possible to form the address wiring by using a wiring material having a lower resistivity. Currently, a Mo-Ta alloy film is often used as an address wiring material. However, the resistivity of this alloy film is as large as 40 Ω · cm, so realization of a large area display is possible with Mo-T.
The resistivity of the a alloy film is considered to be difficult. In particular, in a high-definition direct-view display having about 1000 address wirings, a wiring material having a resistivity of about 20 μΩ · cm or less is required.

The new wiring material as described above is required to have not only a low resistivity but also the following characteristics. Since it is necessary to improve the step coverage of the interlayer insulating film formed on the address wiring and enhance the insulating property between the wiring formed on the interlayer insulating film and the address wiring, the taper processing is possible. Is required.

That is, it is desired to realize a highly reliable liquid crystal display device in which the delay of the gate pulse is suppressed and the insulating property is secured by forming the address wiring by using the wiring material of low resistance. Such a request is not limited to a large area display, but a liquid crystal display device in which wiring and wiring intervals are narrowed in order to achieve high definition of the display,
Alternatively, the same demand is made in a liquid crystal display device or the like in which the wiring width is narrowed to improve the aperture ratio.

The conventional liquid crystal display device also has the following other problems. Here, FIG. 5 is a sectional view of a TFT (switching element) and a storage capacitor portion used in the liquid crystal display device. As shown in FIG. 5, a Mo—Ta alloy is sputtered on the glass substrate 1 to simultaneously form the gate electrode 2, the address wiring, and the Cs line 9. The a-Si active layer 4 is formed through the gate insulating film 3 formed thereon.
Deposit. The n ⁺ a-Si layer 5 is formed on both ends of the active layer 4.
a and 5b are deposited. Then, the ITO pixel electrode 8 is formed via the gate insulating film 3. Then, n ⁺ a-Si layer 5a
Al source electrode 6a, n ⁺ a-Si layer 5 having a connection part at
b and the drain electrode 6b having a connection portion in a part of the pixel electrode 8 and the data wiring are simultaneously formed.

In the conventional TFT shown in FIG. 5,
Since the pixel electrode and the data wiring exist in the same layer without the interposition of the insulating film, they may be short-circuited to cause a point defect. In order to avoid this point defect, a structure in which an interlayer insulating film is formed after the wiring of the source electrode, the drain electrode and the data wiring, and the pixel electrode is formed thereon is being studied as an improvement plan. In order to realize such a structure, (1) the data wiring and the like have excellent resistance to HF which is the etchant of the interlayer insulating film and the ITO etchant of the pixel electrode, (2) the interlayer insulating In order to improve the step coverage of the film and enhance the insulation between the data wiring and the pixel electrode, it is required that the data wiring can be tapered.

[0009]

However, since no wiring material satisfying the above requirements has been found so far, it is difficult to realize the above structure and enhance the reliability of the liquid crystal display device. It was In particular, in developing a large area display, it is important to reduce the occurrence rate of point defects, and development of such a highly reliable liquid crystal display device is desired. Therefore, wiring materials that meet the above requirements,
Furthermore, development of a target for wiring formation is desired.

On the other hand, in Al-based or Ta-based alloys, an oxide film is formed on the surface to increase the contact resistance with the upper metal wiring, so that a step of removing the surface oxide film is required. Further, a barrier metal is required to prevent the reaction between ITO and Al, which has a drawback of increasing the number of manufacturing processes.

An object of the present invention is to provide a wiring forming target and a wiring thin film made of a wiring forming material which has a low resistance and can be tapered. Another object of the present invention is to provide a wiring forming target and a wiring thin film made of a wiring forming material having a low resistance and a high resistance to an etchant such as an interlayer insulating film or ITO.

[0012]

In order to achieve the above object, the present inventors systematically conducted experiments and studies on various metals and alloys as wiring materials in display devices such as liquid crystal display devices. As a result, the alloy film of molybdenum (Mo) and tungsten (W) having a limited composition range has a low resistivity and a low workability as compared with a film composed of only Mo or W constituting them. For the first time, they have found that they are good and have completed the present invention.

That is, the Mo-W target for forming a wiring according to the present invention has an atomic percentage of tungsten of 20 to 95%,
Mo-W consisting of balance molybdenum and unavoidable impurities
Made of alloy material, the Mo-W alloy material has a relative density of 98%
As described above, the average grain size of the crystal grains is 200 μm or less, and M
It is characterized by having a metal structure composed of a solid solution phase of o and W. The Mo-W wiring thin film of the present invention is characterized by being formed by using the above-described Mo-W target for wiring formation of the present invention.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Modes for carrying out the present invention will be described below. The Mo-W material used in the Mo-W target for wiring formation of the present invention is prepared so as to have an atomic percentage of 20 to 95% tungsten, the balance molybdenum and unavoidable impurities.
o material and W material, the composition ratio of W is 20 to 95 in atomic percent
% Alloyed, for example, a sintered body produced by the powder metallurgy method, an ingot produced by the melting method, or the like.

If the W content in the Mo-W alloy material is less than 20% in atomic percent, the resistance increases and the resistance to the etchant such as the interlayer insulating film and ITO decreases. On the other hand, when the W ratio exceeds 95% in atomic percent, the resistance similarly rises. In other words, the Mo-W alloy material in which the W ratio is in the range of 20 to 95% in atomic percent has low resistance and is excellent in etchant resistance. Further, the Mo-W alloy material having the above composition ratio has an advantage that it can be tapered when formed into a thin film, for example.

The proportion of W in the Mo-W alloy material used for the Mo-W target for wiring formation of the present invention is more preferably in the range of 20 to 70% in atomic percent. Within the composition range of W, a practically good sputtering rate can be obtained when a wiring thin film is formed by, for example, a sputtering method. Further, in order to obtain the good sputter rate and the excellent etchant resistance, it is desirable that the W content be in the range of 25 to 45% in atomic percent.

The Mo-W alloy material used in the present invention preferably contains as few impurity elements as possible in order to improve the characteristics of the obtained wiring (Mo-W target and Mo-W wiring). The same applies to thin films). For example, oxygen as an impurity is preferably 500 ppm or less, more preferably 200 ppm or less, desirably 10
It is 0 ppm or less, and more preferably 50 ppm or less. This is because if there is too much oxygen, there are generally many pores (pores), which leads to a decrease in density. This decrease in density increases the generation of particles. In order to reduce the amount of oxygen, it is adopted to reduce powder with hydrogen or to improve sinterability.

The Mo-W wiring thin film of the present invention is formed by using the above-mentioned Mo-W target for wiring formation of the present invention, and is made of the Mo-W alloy having the composition ratio as described above. . The reasons for defining the composition ratio of W, the preferable composition range, and the like are as described above. The address wiring such as a liquid crystal display device made of such a Mo-W wiring thin film acts as a low resistance component with respect to the gate pulse. for that reason,
The gate pulse transmitted through the address wiring is hardly delayed by the resistance component of the address wiring. Therefore, a gate pulse having no delay is given to the switching element for driving the liquid crystal or the like.

Further, since the Mo-W wiring thin film of the present invention can be tapered, the step coverage of the interlayer insulating film formed on the address wiring made of this wiring thin film becomes good. Therefore, a high withstand voltage can be obtained between the wiring formed on the interlayer insulating film and the address wiring. The Mo-W wiring thin film of the present invention further has excellent resistance to an interlayer insulating film and an etchant such as ITO. Therefore,
It is possible to improve the insulation between the data wiring and the pixel electrode. As a result, it is possible to realize a highly reliable liquid crystal display device even when the display area is enlarged.

The Mo-W wiring thin film of the present invention is not limited to a liquid crystal display device having a large area, but a liquid crystal display device in which wiring and wiring intervals are narrowed as the display becomes finer, or wiring width is reduced. It is also effective for a liquid crystal display device which is thin and has an improved aperture ratio. The Mo-W wiring thin film of the present invention can favorably realize narrowing of the wiring width and the wiring interval. Further, the Mo-W wiring thin film of the present invention is effective not only as wiring for liquid crystal display devices but also as wiring for plasma display devices, solid-state display devices, flat-panel display devices using field emission cold cathodes, and the like. .

The Mo-W wiring thin film of the present invention further has the advantage that the resistance of the oxide film formed on its surface is small. Therefore, without performing the oxide film removal process,
A good contact can be formed with the upper metal wiring or the like. Thereby, the manufacturing cost can be reduced. Therefore, the liquid crystal display device manufactured by using the Mo-W wiring thin film of the present invention is different from the conventional liquid crystal display device in that the oxide film is formed on the surface of the gate electrode, the address wiring, and the Cs line. It becomes possible to configure.

The Mo-W target for wiring formation of the present invention enables the Mo-W wiring thin film having the above-mentioned characteristics to be formed with good reproducibility by a thin film forming method such as a sputtering method. However, the composition of the Mo-W wiring thin film varies depending on various conditions such as an atmosphere at the time of forming the wiring thin film, for example, an atmosphere at the time of sputtering, an applied voltage, and the like, but is not unconditionally determined. Within the range of the composition, a good Mo-W wiring thin film can be obtained.

The Mo-W target for wiring formation of the present invention is made of the above-mentioned alloyed Mo-W material. Since Mo and W have different sputtering efficiencies, an alloy target made of a Mo-W alloying material is suitable for reducing the composition variation between the target and the obtained wiring thin film and obtaining a uniform film composition. .

The Mo-W alloy target as described above depends on its manufacturing method and manufacturing conditions, for example, the particle diameter of each powder in the powder metallurgy method, which will be described in detail later, molding conditions, sintering conditions, machining conditions, Those having various densities and structures can be obtained depending on the melting and casting conditions in the melting method.
Furthermore, the density and texture of the target affect the characteristics of the obtained wiring thin film. Therefore, in order to prevent the generation of particles during sputtering and improve the characteristics of the Mo-W wiring thin film, the Mo-W target is preferably dense and has a fine metal structure. The particles cause disconnection or short circuit of the wiring. Specifically, the relative density is 98% or more, and the average grain size of the crystal grains is 200%.
It is preferably μm or less.

Since the above-mentioned Mo-W target is a polycrystalline body in which crystal grains having different crystal orientations are aggregated, the sputter rate varies depending on the crystal orientation of the crystal grains. Therefore,
The larger the crystal grains, the more uneven the sputtered surface is, and a step is formed between the crystal grains. Therefore, the sputtered particles are likely to adhere to the stepped portion or the crystal plane and accumulate. In particular, in the central portion and the end portion of the target, sputtered particles from an oblique direction are unstablely deposited. Such unstablely deposited sputtered particles (or an adhered film due to the sputtered particles) are separated and dropped during the sputtering, which causes particles. Further, at the large step portion, splash due to abnormal discharge occurs and particles are generated.

If the crystal grains in the Mo-W target are miniaturized, the above-mentioned generation of particles can be suppressed. Therefore, the average grain size of the crystal grains is preferably 200 μm or less, more preferably 100 μm or less, and further preferably 50 μm or less. Here, the grain size of the crystal grains in the present invention refers to the value of “(major axis + minor axis) / 2” of the crystal grains when a cross section of an arbitrary polished surface in the sputtering surface direction is observed at a magnification of 100 times. It is a thing. The average grain size of the crystal grains is the average value of the crystal grains present in the visual field obtained by measuring the polished surface in 30 or more visual fields.

When pores are present in the Mo-W target, sputtered particles knocked out by Ar ions entering the pores during sputtering deposit on the edges of the pores to form protrusions. This protrusion causes abnormal discharge,
Generate particles. When the Mo-W target is densified, the above-mentioned generation of particles can be suppressed. Therefore, the relative density of Mo-W target is 98.
% Or more, more preferably 99% or more, and further preferably 100%.

Further, the residual processing strain of the Mo-W target also affects the generation of particles. When a large processing strain remains in the target, the sputter rate locally changes due to the influence of the residual strain. Due to this difference in sputtering rate, many stepped portions are generated on the sputtering surface, and the amount of particles generated increases. The work strain can be eliminated by heat treatment, and it can be judged by the hardness that decreases as the work strain decreases. Therefore, Mo-
In the case of a W target, the Vickers hardness is preferably Hv350 or less, more preferably Hv300 or less, and further preferably Hv250 or less.

The specific structure of the above-described Mo-W target has a uniform solid solution phase structure of Mo and W, and Mo and / or W in the solid solution phase of Mo and W depending on the manufacturing method and manufacturing conditions. It is possible to obtain various structures such as a structure existing in a simple phase and a structure in which a solid solution phase of Mo and W exists in a simple phase of Mo and / or W. Among these, it is particularly preferable that Mo and W are uniformly distributed in the target, and therefore the structure of the Mo-W target is preferably a solid solution phase of Mo and W.

A more specific form of the Mo-W target for wiring formation of the present invention is, for example, (a) manufactured by a powder metallurgy method using a mixed powder containing Mo powder and W powder in a predetermined composition ratio. Examples of the target include (b) a target manufactured by a melting method so that Mo and W have a predetermined composition ratio, and the like.

An example of the method of manufacturing the target (a) will be described below. First, Mo powder and W powder are mixed in a ball mill to prepare a uniform mixed powder. At this time, nylon or ceramics can be applied to the material of the ball, but by using Mo or W as the material of the inner wall of the ball mill and the ball used, the amount of impurities mixed in the target can be reduced. .

Next, the mixed powder is filled in a carbon mold or the like and sintered. Hot pressing in vacuum can be applied to the sintering. Further, in order to improve the sinterability and make it dense, a combination of isotropic pressure molding such as cold isostatic pressing (CIP) and sintering in a reducing atmosphere such as hydrogen atmosphere is applied. Good. Further, it is effective to further densify the target material by subjecting the sintered body obtained by these methods to hot working such as HIP treatment, forging and rolling.

The hot pressing is preferably carried out under conditions of a heating temperature of 1973 K or higher and a surface pressure of 20 MPa or higher, and more preferable conditions are a heating temperature of 2073 K or higher and a surface pressure of 30 MPa or higher. Similarly, the sintering after pressure molding is preferably performed at a temperature of 1973K or higher, more preferably 2073K or higher. HIP
The preferred conditions for treatment are heating temperature of 1773K or higher and pressure of 150MP.
a or more, more preferably heating temperature 2073K or more, pressure
180MPa or more. This is because if the heating temperature and the surface pressure are too low, the sintering is difficult to proceed and it is difficult to obtain a target material composed of a high-density sintered body.

The target material obtained by the powder metallurgy method described above is subjected to mechanical processing such as grinding to obtain an M-shaped material having a predetermined shape.
ow target.

As the target (b), a sintered body made of, for example, Mo, W and inevitable impurities is produced by a powder metallurgy method, and then an ingot is produced by a melting method such as electron beam melting. After that, if necessary, hot working such as forging or rolling is performed, and then mechanical processing such as grinding is performed to obtain a Mo-W target having a predetermined shape.

As described above, the Mo-W target for wiring formation of the present invention preferably satisfies the above-mentioned conditions regarding the density and the structure in order to prevent the generation of particles during sputtering. For this reason,
In particular, it is preferable to apply a manufacturing method which is a combination of powder metallurgy and hot working. By subjecting the sintered body by the powder metallurgy method to hot working, it is possible to make the target material highly dense while maintaining a fine crystal grain size. For example, if the relative density is 98% or more and the average grain size of the crystal grains is 200 μm
The following Mo-W targets are obtained. Since the crystal grain size of the target material produced by the melting method is likely to be coarsened, there is a risk that the mechanical strength may be deteriorated or cracks may occur during hot working.

The sintered body to be hot-worked as described above preferably has a relative density of 90% or more. If the relative density of the sintered body is too low, the target material may not be finally densified even if hot working is performed. The sintered body to be subjected to hot working is preferably a sintered body of a pressure molded body such as CIP. According to the hot pressing, Mo and W may react with the carbon mold when the temperature is high enough to allow densification.

Thus, the Mo-W for wiring formation of the present invention
A preferable manufacturing method of the target is a predetermined composition ratio (W:
Molded mixed powder adjusted to 20-95at%) (especially CIP
Etc.), the step of sintering the compact in a reducing atmosphere such as a hydrogen atmosphere, and the step of hot working the sintered body. Further, the target material after hot working is preferably subjected to strain relief heat treatment in order to remove residual working strain.

The specific conditions of the above-mentioned target manufacturing method are as follows. The density as described above,
In order to obtain a Mo-W target having a metal structure and hardness, the processing temperature during sintering in a reducing atmosphere such as a hydrogen atmosphere, the processing temperature and processing rate during hot working, and the subsequent heat treatment temperature are important. It becomes a factor.

First, the sintering temperature in a reducing atmosphere such as a hydrogen atmosphere affects the density of the target material. Therefore, the sintering temperature is preferably 2173K or higher. If the sintering temperature is less than 2173K, it will be difficult to achieve a relative density of 98% or more even after hot rolling. The sintering time increases in density as the time increases, but if the time is too long, the productivity decreases, so about 5 to 30 hours is appropriate. A more preferable treatment temperature is 2272K or higher, and further preferable is 2473K or higher. A more preferable sintering time is about 10 to 25 hours.

The processing temperature during hot working is an important factor for preventing cracks during working and for stable manufacture. In particular, pure tungsten tends to become brittle at 1473 K or less, and it is necessary to raise the processing temperature as the W content increases. Therefore, the treatment temperature is preferably 1673K or higher, and more preferably 1873K or higher. Further, the treatment time is preferably about 2 to 8 hours in consideration of soaking properties of the sintered body.

Further, when hot working is performed by hot rolling,
In order to set the relative density of the target to 98% or more, it is preferable to set the rolling rate to 50% or more. Furthermore, the rolling rate is
It is more preferably at least 60%, further preferably at least 70%. Here, the rolling ratio (%) in the present invention is the ratio of the thickness of the sintered body before rolling to the thickness after rolling (processing), (((thickness of sintered body before rolling-rolling (Thickness after processing) / thickness of sintered body before rolling) × 100.

The strain relief heat treatment performed after hot rolling is 1473-
It is preferred to operate at a temperature in the range of 1923K. If the heat treatment temperature is less than 1473K, the residual strain may not be sufficiently removed, while if it exceeds 1923K, pores may be generated in the material and particles may be generated. The strain relief heat treatment temperature is preferably set in the range of 1673 to 1823K.

Target (a) and target described above
(b) is preferably manufactured integrally, in order to prevent generation of particles during thin film formation, but a plurality of targets having the same composition may be used in combination for the purpose of increasing the size of the target. In this case, the plurality of targets are fixed by brazing to a backing plate or the like, but in particular, in order to prevent generation of particles from the edge portion,
The targets are preferably diffusion bonded. As the diffusion bonding method, a direct bonding method, a bonding method with Mo and / or W interposed in the bonding section, or a M bonding method in the bonding section.
Various methods such as a method of joining by interposing an o and / or W plating layer are adopted.

[0045]

EXAMPLES Next, specific examples of the present invention will be described.

Example 1 Mo powder having an average particle size of 10 μm and W powder having an average particle size of 10 μm were mixed in various atomic percentages, and the mixture was put into a ball mill whose inner wall was covered with Mo and made of nylon. The mixture was mixed for 48 hours with a ball of No. 1 to obtain a plurality of uniform mixed powders. After filling each of the obtained mixed powders into a carbon mold, sintering was performed by vacuum hot pressing under the conditions of a heating temperature of 2073K, a heating time of 5 hours, and a surface pressure of 30 MPa to obtain a sintered body having a density of 97%, respectively. It was Thereafter, each of the obtained sintered bodies was subjected to machining such as cutting and grinding to obtain Mo-W targets having various compositions with a diameter of 250 mm and a thickness of 8 mm.

These Mo-W targets were bonded to an oxygen-free copper backing plate with an In brazing material and then mounted on a sputtering device. Using such a sputtering device, the distance between the glass substrate, which is the film formation substrate, and the target was set to 70 mm, and after heating the glass substrate, sputtering was performed with a DC power source at an input power of 1 kW and an Ar pressure of 0.5 Pa. , Mo-W alloy films were formed.

The resistivity of each Mo-W alloy film obtained was measured. The results are shown in FIG. 1 as a relationship with the W content.
As is clear from FIG. 1, the Mo—W wiring thin film (W content = 20 to 95 at%) of the present invention has a resistivity of much less than 40 μΩ · cm, and has a Mo film and a W film. It has a lower resistivity than a single film of material.

Next, an example in which a wiring thin film formed by using the above Mo-W target is applied to a liquid crystal display device will be described. FIG. 5 is a sectional view showing an example of a TFT (switching element) and a storage capacitor portion used in a liquid crystal display device. The structure and process of the TFT and the storage capacitor portion will be described.

On the glass substrate 11, the above-mentioned M of the present invention is formed.
300 nm sputtering is performed using an OW target to form the gate electrode (control electrode) 2, the address line, and the Cs line 9 at the same time. Then, the oxide film 3 is deposited to 350 nm by plasma CVD.
After the formation, an a-Si active layer 4 is formed to 300 nm, and an n ⁺ a-Si layer 5 is formed.
A film of a and 5b is continuously formed to a thickness of 50 nm to form an a-Si island portion. Next, ITO is sputtered with a thickness of 120 nm to form the pixel electrode 8. Next, SiO _x in the contact portion is etched with diluted HF to form a contact hole.
Then, a predetermined wiring metal such as Al is sputtered, and the source electrode (first electrode) 6a, the drain electrode (second electrode) 6b and the data wiring are simultaneously formed by wet etching. At this time, surface oxidation treatment was required before sputtering Al or the like.

Since the Mo-W wiring thin film of the present invention formed by using the Mo-W target of the present invention has a low resistivity, the address wiring formed by using the thin film of the present invention exhibits a low resistance. . As a result, the gate pulse was not delayed by the wiring resistance, and the gate pulse without delay in the predetermined switching element was obtained.

Further, since the Mo-W wiring thin film of the present invention can be tapered, the step coverage of the interlayer insulating film formed on the address wiring formed by using this alloy film becomes good, and the withstand voltage is increased. It was possible to secure a high price. Therefore, it becomes possible to realize a highly reliable liquid crystal display device even when the display area is enlarged. Table 1 shows the relationship between the composition ratio of the Mo-W target and the taper angle.

[0053]

[Table 1]

To measure the taper angle, the cross section of the thin film is SE
It is observed by M and the angle with the glass substrate is measured. As is clear from Table 1, the taper angle increases as the W ratio increases, and it is understood that the taper processing is good within the composition range of the present invention.

Next, in order to measure the chemical resistance of the Mo--W alloy films of the above various compositions, the etchant of ITO which is a pixel electrode material and the BH which is an etchant of an interlayer insulating film.
The etching rate (nm / min) for F and Al etchants was measured. The result is shown in FIG.

As is clear from FIG. 2, the etching rate of the Mo--W alloy film is 8 nm / min or less for the ITO etchant and 3-40 nm for the Al etchant.
/ min or less and BH which is an etchant for the interlayer insulating film
F did not etch at all. Especially, W is 50
It was found that the etching was not performed at all when the content was at% or more. Therefore, even if a pinhole occurs in the interlayer insulating film, the wiring under the interlayer insulating film, such as the gate electrode and the data line, is not corroded by the above etchants. Therefore, there is an advantage that the degree of freedom in structural design / process design above the interlayer insulating film can be increased.

FIG. 3 shows the results of measuring the stress (dyn / cm ² ) of the Mo-W alloys of the above various compositions. As is clear from FIG. 3, since the stress greatly changes depending on the composition ratio, it becomes possible to reduce the stress by adjusting the composition ratio.

FIG. 4 shows the measurement results of the sputter rate (nm / min) when a Mo-W alloy film was obtained by sputtering using a Mo-W target. This sputter rate is measured by the following method. First, the adhesion of the Mo-W alloy film after sputtering was measured on the film thickness measurement points from the four corners of the glass substrate toward the center of the substrate, and from the center of the four sides toward the opposite sides. Mark with oil-based ink for the purpose of reducing Then, after forming a Mo-W alloy film by performing sputtering, an adhesive tape is attached to a portion marked with the oil-based ink, and the tape is peeled off, so that the Mo-W alloy film on the oil-based ink is also peeled off. Let Then, only the oil-based ink is wiped with an organic solvent or the like to obtain a glass substrate surface. Then, the step difference between the portion where the Mo—W alloy film was peeled off and the other portion where the Mo—W alloy film was not peeled off was measured at the same position from the edge portion toward the central portion by the step difference measuring device. The obtained film thickness is the sputter rate (nm / m
in).

As is apparent from FIG. 4, the sputter rate is good when the W ratio tends to be low. Considering the etchant resistance as shown in FIG. 2, the W ratio should be 25%.
It is clear that it is desirable to set the range of ~ 45at%.

The above-described embodiment is an example of the present invention, and the thickness of each layer and the film forming method can be appropriately changed and carried out. Even in such a case, the same effect as this embodiment can be obtained. Further, the TFT has another structure, for example, a TFT having a structure in which a stopper of an insulating film is provided on the channel.
Etc. can also be used. The storage capacitor portion may have a structure formed in a wiring in the same layer as the gate electrode and a wiring in the same layer as the data wiring.

Example 2 Mo powder having an average particle size of 10 μm and W powder having an average particle size of 10 μm were mixed with W
After blending so as to have an atomic% of 20 to 95%, the mixture is put into a ball mill whose inner wall is covered with Mo and mixed for 30 hours using nylon balls to obtain a uniform mixed powder. It was The obtained mixed powder was filled in a molding die and the pressure was adjusted to 20
The wet-CIP treatment was performed under the condition of 0 MPa. The obtained molded body is sintered in a hydrogen atmosphere under the conditions of 2073K × 10 hours,
A sintered body having a density of 90% was obtained. After that, the obtained sintered body is machined by cutting and grinding to have a diameter of 250 mm and a thickness of 8 mm.
Mo-W targets having various compositions of This M
Place the OW target on the oxygen-free copper packing plate I
Bonding was performed using an n-based brazing material, and the brazing material was attached to a sputtering device.

FIG. 6 is a sectional view of a TFT and a storage capacitor portion used in a liquid crystal display device different from that of the first embodiment.
The structure and process of the TFT and the storage capacitor portion will be described. On the glass substrate 11, 300 nm of a predetermined wiring metal such as Mo-Ta is sputtered to simultaneously form the gate electrode 12, the address line and the Cs line 19. Then, the oxide film or nitride film 13 is removed by plasma CVD.
After forming 0 nm, the a-Si layer 14 is 300 nm, and the n ⁺ a-Si layer 15 is
A film of a and 15b is continuously formed to a thickness of 50 nm to form an a-Si island portion. Next, after forming the contact hole by etching with diluted HF, the surface oxide film is removed.

Then, after sputtering using the above-mentioned Mo-W target of the present invention, the source electrode 16a, the drain electrode 16b and the data wiring are simultaneously formed by wet etching. Then, after forming an oxide film 17 with a thickness of 300 nm, etching with an HF-based solution (for example, an etching rate of about 10 nm / min) or dry etching using a gas such as CF ₄ (for example, an etching rate of about 3 to 10 n) is performed.
m / min) to form a contact hole on the drain electrode 16b, and sputter ITO 120 nm to form the pixel electrode 18
To form.

The Mo-W wiring thin film formed by using the above-described Mo-W target of the present invention has excellent chemical resistance as described in Example 1. The data wiring made of such a Mo-W wiring thin film having excellent chemical resistance contains an alkaline etchant (pH 7 to 13) containing an oxidizing agent having a higher redox potential than the etchant used for etching the Mo film or the W film. By using it, it was possible to perform taper processing without deteriorating the resist.

Therefore, in the pixel array thus formed, the data wiring is tapered, so that the stop coverage of the interlayer insulating film formed on the data wiring becomes good and a high withstand voltage can be secured. Further, since the drain electrode 16b has excellent chemical resistance, it is possible to form a contact hole with HF on the drain electrode 16b, and it is also possible to process the pixel electrode with a mixed liquid of chlorine and nitric acid. there were. Furthermore, M of the present invention
It has been found that when a wiring is formed by using an o-W wiring thin film, unlike Al, hillock does not occur, and since a reaction with ITO does not occur, a barrier metal is unnecessary.

As shown in Example 1, the Mo-W wiring thin film of the present invention has the advantage of basically low resistance, and the stress changes greatly depending on the composition ratio of the Mo-W alloy. Therefore, it is possible to reduce the stress.

The above-mentioned embodiment is an example of the present invention, and the thickness of each layer and the film forming method can be appropriately changed and carried out. Even in such a case, the same effect as this embodiment can be obtained. Further, the TFT has another structure, for example, a TFT having a structure in which a stopper of an insulating film is provided on the channel.
Etc. can also be used. The storage capacitor portion may have a structure formed in a wiring in the same layer as the gate electrode and a wiring in the same layer as the data wiring.

Example 3 Mo powder having an average particle size of 10 μm and W powder having an average particle size of 10 μm were mixed with W
After blending so that the atomic% of the mixture is in the range of 20 to 95%, the mixture is put into a ball mill whose inner wall is coated with Mo and mixed for 24 hours using nylon balls to obtain a uniform mixed powder. It was The obtained mixed powder is filled in a molding die and the pressure is 200M.
It was wet-CIP processed under Pa condition. The obtained molded body,
Sintered in a hydrogen atmosphere at 2073K for 8 hours to give a density of 90
% Sintered body was obtained.

Furthermore, 2073K, 4 hours, 180M to this sintered body
HIP treatment was performed under the condition of Pa to obtain a sintered body having a density of 98%. Then, the obtained sintered body was machined by cutting and grinding to obtain a target piece having a length of 180 mm, a width of 180 mm and a thickness of 6 mm. The target piece thus obtained is vertically
A combination of 3 pieces and 2 pieces in the lateral direction was used as a Mo-W target. This Mo-W target was bonded to an oxygen-free copper backing plate with an In-based brazing material and attached to a sputtering device.

FIG. 7 is a sectional view of a TFT and a storage capacitor portion used in a liquid crystal display device different from those of the first and second embodiments. In the liquid crystal display device of this embodiment, the Mo-W of the present invention described above is provided on the glass substrate 21 as in the first embodiment.
Sputtering 300 nm using a target, gate electrode 2
2, the address line and the Cs line 29a are formed at the same time. Then, similarly to the second embodiment, after sputtering using the Mo—W target of the present invention, the source electrode 26a, the drain electrode 26b and the data wiring are simultaneously formed by wet etching.

The liquid crystal display device of the third embodiment is the same as the second embodiment.
In place of the back channel cut type TFT which etches the channel portion applied in (2), a TFT having a structure in which a stopper of an insulating film is provided on the channel is used.
The storage capacitor portion is formed by wiring in the same layer as the gate electrode and in the same layer as the data wiring.

That is, M of the present invention is placed on the glass substrate 21.
The gate electrode 2 is sputtered using an OW target.
2, the address line and the Cs line 29a are formed at the same time. Next, the interlayer insulating film 23, the a-Si layer 24, and the channel protection layer 3
0, n ⁺ a-Si layers 25a and 25b are continuously formed. Then, sputtering is performed using a Mo-W target to form the source electrode 26a, the drain electrode 26b, the data wiring and Cs.
The line 29b is formed at the same time. Then, after forming the oxide film 27, a contact hole is formed on the drain electrode 26b to form a pixel electrode 28.

According to the third embodiment described above, both the effects of the first embodiment and the effects of the second embodiment can be obtained.

Here, the present invention is not limited to the above-mentioned embodiments, and the semiconductor is not limited to a-Si, but p-Si,
It may be formed using CdSe or the like. The insulating film on the data wiring is not limited to the oxide film, but may be a nitride film. further,
In the wiring thin film of the present invention, instead of adopting the one-layer structure as in the above embodiment, Mo-W having a different composition is used.
It may be formed as a laminated film of two or more layers made of an alloy. The oxidation resistance may be improved by laminating Ta, TaN or the like on the upper layer of the wiring thin film of the present invention. Further, Al, Cu or the like may be laminated on the lower layer of the wiring thin film of the present invention to reduce the resistance.

Example 4 A mixed powder prepared by mixing Mo powder having an average particle size of 4.5 μm and W powder having an average particle size of 3.6 μm in a predetermined ratio was used.
After filling the rubber mold for molding, apply a pressure of 200 MPa to C
A molded body was prepared by adding by IP. Next, the obtained molded body was sintered in a hydrogen atmosphere under various conditions. The sintering conditions are as shown in Tables 2 and 3. Further, these sintered bodies were heated in a hydrogen atmosphere to carry out hot rolling of the cloth. The rolling conditions are as shown in Tables 2 and 3. These rolled materials were heat-treated under the conditions shown in Tables 2 and 3, and then machined to obtain Mo-W targets each having a diameter of 250 mm and a thickness of 8 mm. In this way, each Mo of No1 to No40 shown in Table 2 and Table 3
-W target was obtained.

The reference examples (No41 to No48) in Table 3 are
Example 4 above, except that any of the hydrogen sintering conditions, rolling conditions, and heat treatment conditions was outside the preferred range in the present invention.
It is a Mo-W target produced in the same manner as.

Each M according to the fourth embodiment and the reference example described above
The relative density of the OW target, the average grain size of the crystal grains, and the Vickers hardness were measured. The results are shown in Table 4 and Table 5.
Shown in. Further, each Mo-W target was mounted on a DC magnetron sputtering apparatus, and a Mo-W alloy film (thickness = 30 nm) was sputter-deposited on the surface of a 6-inch Si wafer. The number of particles of 0.3 μm or more present in the obtained Mo—W alloy film was examined. The measurement result of the number of particles is the measurement result of the number of particles in the Mo—W alloy film after removing 5 mm from the edge portion of the 6-inch Si wafer. The results are also shown in Tables 4 and 5.

[0078]

[Table 2]

[0079]

[Table 3]

[0080]

[Table 4]

[0081]

[Table 5]

As is clear from Tables 4 and 5, each Mo-W target according to Example 4 had a relative density of 98% or more and a Vickers hardness of Hv350 or less. It has been found that the number of particles generated can be significantly reduced by forming a film using such a Mo-W target.

In addition, Mo-of Sample No. 11 in Example 4
An optical micrograph (magnification 100 times) showing the metal structure of the W target is shown in FIG. 8, and an optical micrograph showing the metal structure of the Mo-W target of Sample No. 15 is magnified (magnification 100).
9), and FIG. 10 shows an optical micrograph (magnification 100 times) showing an enlarged metal structure of the Mo-W target of Sample No. 31 in FIG. In addition, Mo-of sample No. 47 in the reference example
FIG. 11 shows an optical micrograph (magnification: 100 times) showing an enlarged metal structure of the W target.

FIG. 8 shows a metal structure that has been strain-relieved. On the other hand, FIG. 11 shows a state in which sufficient strain relief is not performed because the temperature of the strain relief heat treatment is low. 9 and 10 are distorted,
Moreover, the state of recrystallization is shown. As shown in FIG. 9 and FIG. 10, since the strain is completely removed by recrystallization, it is particularly suitable as the Mo—W target of the present invention. Although FIG. 8 shows a state in which the strain is removed, it is not as complete as in FIGS. 9 and 10, and since some strain remains, there is a risk of warping during use and peeling from the backing plate. . Therefore, it is preferable to recrystallize. However, as shown in FIG. 10, if the temperature of the strain relief heat treatment is too high, some pores are generated in the crystal, so it is preferable to set the temperature at which pores are not generated.

Further, when the liquid crystal display devices shown in the above-mentioned Examples 1, 2 and 3 were produced by using the Mo-W target according to the above Example 4, similar good results were obtained. Was given. Further, since the Mo-W wiring thin film formed by using the Mo-W target according to Example 4 has a significantly small number of particles, it was possible to further improve the electrical characteristics of the address wiring and the data wiring. .

The present invention is not limited to the configurations and manufacturing methods of the above-described embodiments, but uses the Mo-W target for forming the wiring thin film of the present invention, or of the present invention. It is applied to all those using Mo-W wiring thin film. For example, the present invention is effective not only for wiring of a liquid crystal display device but also for wiring of a plasma display device, a solid-state display device, a flat-panel display device using a field emission cold cathode, and the like.

[0087]

As described above, the Mo-W target for wiring formation of the present invention has a low resistance, can be tapered, and is excellent in the etchant resistance.
Since it is made of an alloy, it is very effective as a material for forming address wiring and data wiring of a liquid crystal display device or the like. Since the Mo-W wiring thin film of the present invention uses the above-mentioned Mo-W alloy, it greatly contributes to the improvement of operating characteristics and reliability of liquid crystal display devices and the like. Further, the wiring forming Mo of the present invention
The -W target makes it possible to form such a Mo-W wiring thin film satisfactorily and with good reproducibility.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a resistivity of a Mo—W alloy and a W content rate.

FIG. 2 is a diagram showing the relationship between the etching rate and the W content of each Mo—W alloy etchant.

FIG. 3 is a diagram showing the relationship between stress and W content of Mo—W alloy.

FIG. 4 is a diagram showing a relationship between a W content rate and a sputtering rate when a Mo—W alloy film is obtained by sputtering using a Mo—W target.

FIG. 5 is a cross-sectional view of a TFT and a storage capacitor portion used in a liquid crystal display device.

FIG. 6 is a cross-sectional view of a TFT and a storage capacitor portion used in another liquid crystal display device.

FIG. 7: TFT used in still another liquid crystal display device
It is a sectional view of a storage capacitor portion.

FIG. 8 is an enlarged micrograph showing a metal structure of a Mo—W target formed in one example of the present invention.

FIG. 9 is a micrograph showing an enlarged metal structure of a Mo—W target formed in another example of the present invention.

FIG. 10 is a view of Mo formed according to still another embodiment of the present invention.
It is a microscope picture which expands and shows the metal structure of -W target.

FIG. 11 is an enlarged micrograph showing a metal structure of a Mo—W target formed as a reference example.

[Explanation of symbols]

1, 11, 21, ... glass substrate, 2, 12, 22, ... gate electrode, 3 ... oxide film, 4, 14, 24 ... a-Si
Layer, 6a, 16a, 26a ... Source electrode, 6b, 16
b, 26b ... Drain electrode, 8, 18, 28 ... Pixel electrode, 9, 19, 29a ... Cs line, 13 ... Oxide film or nitride film, 23 ... Interlayer insulating film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/3205 H01L 21/88 M 29/786 29/78 617M (72) Inventor Yoshiko Tsuji Kawasaki City, Kanagawa Prefecture 1-2-2-101 Watata, Kawasaki-ku (72) Mitsushi Ikeda 2-3-20-711 Tarumacho, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture (72) Michio Sato 488-7 Sugata-cho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture − 1-205 (72) Inventor Toshihiro Maki 3-8-15-P 2-101 F term, Konan-ku, Yokohama-shi, Kanagawa Prefecture 3-8-15-P 2-101 F term (reference) 4K029 AA09 AA24 BA21 BC03 BC07 BD00 BD02 CA05 DC04 DC09 4M104 AA01 AA08 AA09 AA10 BB02 BB04 BB16 BB18 BB37 BB39 CC05 DD37 DD40 FF08 GG09 HH13 HH16 5F033 GG04 HH08 HH11 HH21 HH22 HH32 HH38 JJ01 JJ38 LL08 LL09 MM19 PP15 QQ09 QQ19 QQ34 QQ37 QQ92 QQ94 RR04 RR06 SS15 VV06 VV15 WW00 WW01 WW04 XX02 XX0 9 XX10 XX34 5F110 AA01 AA16 AA26 AA28 BB01 CC07 DD02 EE01 EE02 EE03 EE04 EE06 EE12 EE15 EE23 EE44 FF02 NN HL23 HL HL HL HL 04 HL HL HL 04 HL 04 HL 04 HK HK HK 04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 HK04 NN73 QQ09

Claims (8)

[Claims] 1. Tungsten 20-95 in atomic percent
%, The balance molybdenum and inevitable impurities Mo
-W alloy material, the Mo-W alloy material has a relative density
A Mo-W target for forming a wiring, comprising 98% or more, an average grain size of crystal grains of 200 µm or less, and having a metal structure composed of a solid solution phase of Mo and W. 2. The Mo-W target for wiring formation according to claim 1, wherein the composition ratio of the tungsten is 20 to 70 in atomic percent.
% Of Mo-W target for wiring formation. 3. The Mo-W target for wiring formation according to claim 1, wherein the average grain size of the crystal grains is 100 μm or less. 4. The Mo-W target for wiring formation according to claim 1, wherein the amount of oxygen in the Mo-W target is 500 ppm or less. 5. A Mo-W formed by using the Mo-W target for wiring formation according to claim 1.
Wiring thin film. 6. The Mo—W wiring thin film according to claim 5, wherein the composition ratio of the tungsten is 20 to 70 in atomic percent.
% Mo MoW wiring thin film. 7. A liquid crystal display device using the Mo—W wiring thin film according to claim 5 for at least a part of wiring. 8. The liquid crystal display device according to claim 7, wherein the Mo—W wiring thin film is used as at least one of a gate electrode, an address line and a Cs line.