KR20130028621A

KR20130028621A - Cylindrical sputtering target material, wiring board and thin film transistor using the same

Info

Publication number: KR20130028621A
Application number: KR1020120025831A
Authority: KR
Inventors: 고시로 우에다; 노리유키 다쓰미; 류이치 고바야시
Original assignee: 히타치 덴센 가부시키가이샤
Priority date: 2011-09-09
Filing date: 2012-03-14
Publication date: 2013-03-19
Also published as: JP2013057112A; JP5723247B2; CN102994962B; CN102994962A

Abstract

PURPOSE: A cylindrical sputtering target object, a wiring substrate, and a thin film transistor using the same are provided to slow a sputtering speed in the inner periphery in comparison with that in the outer periphery as the hardness of the cylindrical sputtering target object is gradually increased from the outer periphery to the inner periphery. CONSTITUTION: A cylindrical sputtering target object is formed of oxygen-free copper having purity of 3N or greater and into a cylindrical shape. An orientation rate of a surface is gradually increased from the outer periphery to the inner periphery of the cylindrical sputtering target object as the hardness of the cylindrical sputtering target object is gradually increased from the outer periphery to the inner periphery. Even though the thickness of the sputtering target object is gradually decreased by using the cylindrical sputtering target object, a sputtering speed of the cylindrical sputtering target object is regularly maintained.

Description

Cylindrical sputtering target material, wiring board and thin film transistor using the same {CYLINDRICAL SPUTTERING TARGET MATERIAL, WIRING BOARD AND THIN FILM TRANSISTOR USING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board and a thin film transistor provided with a cylindrical sputtering target material having a cylindrical shape, a sputtering film formed using the same.

Recently, due to the high precision of liquid crystal display devices such as large display panels, miniaturization of thin film transistor (TFT) array wiring is required. As such a wiring material, copper (Cu) having a low electrical resistivity has become a mainstream in place of aluminum (Aｌ) conventionally adopted.

Fine copper wiring on the thin film transistor substrate is formed by, for example, sputtering. At that time, in planar sputtering target materials, which are widely used disc or square plates, erosion proceeds locally so that the utilization rate of the target materials is 30% to 40. The drawback is that it is very low, around%.

Therefore, in recent years, a cylindrical sputtering target material which sputters while rotating the target material has been used. As a result, since the erosion proceeds in the entire surface of the target material, the utilization rate of the target material is 60% or more, and a significantly higher value can be obtained than the planar type.

As a manufacturing method of a cylindrical sputtering target material, the method of making a molybdenum alloy material into a cylindrical shape by spinning process (for example, refer patent document 1), or the outer peripheral surface of a cylindrical base material ) And a method of joining a target material made of a cylindrical ceramic sintered body (see Patent Document 2) and the like have been proposed.

Japanese Patent Laid-Open No. 2007-302981 Japanese Patent Laid-Open No. 2008-184627

For example, the cylindrical sputtering target material using copper can be manufactured more inexpensively if expansion pipe drawing processing etc. are used instead of the method of patent document 1 and patent document 2 with high production cost.

However, when the cylindrical sputtering target material is manufactured by expansion drawing, the hardness gradually increases from the outer circumferential surface side toward the inner circumferential surface side, resulting in a slower sputter speed on the inner circumferential surface side than the outer circumferential surface side.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cylindrical sputtering target material capable of achieving uniform sputtering speed from the outer circumferential surface side to the inner circumferential surface side, a wiring board using the same, and a thin film transistor.

According to the first aspect of the present invention, a cylindrical sputtering target material formed of oxygen-free copper having a purity of 3 N or more and having a cylindrical shape, the hardness gradually increasing from the outer circumferential surface side to the inner circumferential surface side, and the inner circumferential surface side from the outer circumferential surface side. A cylindrical sputtering target material is provided in which the orientation ratio of the (111) plane gradually increases.

According to the second aspect of the present invention, even when the thickness of the cylindrical sputtering target material is gradually reduced by the use of the cylindrical sputtering target material, the hardness is increased from the outer peripheral surface side toward the inner peripheral surface side so that the sputtering speed of the cylindrical sputtering target material becomes constant. The decrease of the sputtering speed of the said cylindrical sputtering target material by gradually increasing, and the increase of the sputtering speed of the said cylindrical sputtering target material by gradually increasing the orientation ratio of (111) surface from the said outer peripheral surface side toward the said inner peripheral surface side cancel out. The cylindrical sputtering target material described in the first aspect is provided.

According to the third aspect of the present invention, the hardness is Vickers hardness, the Vickers hardness of the outer circumferential side is 75 HPa or more and 80 HPa or less, and the first or second aspect of the Vickers hardness of the inner circumferential side is 95 HPa or more and 100 HＶ. The cylindrical sputtering target material described in is provided.

According to the 4th aspect of this invention, the orientation ratio of the said (111) surface of the said outer peripheral surface side is 10% or more and 15% or less, and the orientation ratio of the (111) surface of the said inner peripheral surface side is 20% or more and 25% or less The cylindrical sputtering target material as described in any one of 1-3 is provided. However, the orientation ratio of the (111) plane is the sum of the values obtained by dividing the measured intensity of each peak by X-ray diffraction divided by the standard intensity of the peak of the crystal plane corresponding to each of the peaks described in PCB card number 40836, respectively. And the value obtained by dividing the measured intensity of the peak of the (111) plane by X-ray diffraction by the standard intensity of the peak of the (111) plane described in PCB card No. 40836 from the formula in terms of a molecule.

According to the 5th aspect of this invention, the cylindrical sputtering target material in any one of the 1st-4th aspect whose crystal grain size exists in the range of 50 micrometers or more and 100 micrometers or less is provided.

According to the sixth aspect of the present invention, there is provided the cylindrical sputtering target material according to any one of the first to fifth aspects, which is formed by performing expansion pipe drawing and heat treatment on an extruded pipe.

According to a seventh aspect of the present invention, there is provided a wiring board having a substrate and a wiring structure formed on the substrate, wherein at least a part of the wiring structure is formed of a sputtering film formed using the cylindrical sputtering target material according to the first aspect. do.

According to the eighth aspect of the present invention, there is provided a wiring structure formed on the substrate and comprising a source electrode and a drain electrode, wherein at least a part of the wiring structure is a first aspect. There is provided a thin film transistor comprising a sputtering film formed by using the cylindrical sputtering target material described in.

According to the present invention, the sputtering speed from the outer peripheral surface side to the inner peripheral surface side of the cylindrical sputtering target material can be made uniform.

1 is a view showing a cylindrical sputtering target material according to one embodiment of the present invention, (a) is a perspective view of a cylindrical sputtering target material, and (b) is a cross sectional view of the cylindrical sputtering target material.
Fig. 2 is a cross-sectional view showing the shape of expansion pipe drawing for producing the cylindrical sputtering target material according to one embodiment of the present invention.
Fig. 3 is a schematic explanatory view showing the shape of sputtering using a cylindrical sputtering target material according to one embodiment of the present invention, (a) is an oblique perspective view of a sputtering apparatus equipped with a cylindrical sputtering target material, (b) Is a cross-sectional view of a cylindrical sputtering target material.
4 is a schematic cross-sectional view of a thin film transistor according to one embodiment of the present invention.
5 is a cross-sectional view showing a measurement position of an evaluation sample of cylindrical sputtering target materials according to Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention.

As described above, in the cylindrical sputtering target material manufactured by expansion drawing, for example, the inner circumferential surface side is harder than the outer circumferential surface side, so that the sputtering speed of the inner circumferential surface side is slower than the outer circumferential surface side. have.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the inventors considered that the (111) surface which is the closest surface of copper (Cu) uses the crystal orientation which a copper atom easily protrudes by sputtering. It was early. That is, an attempt was made to distribute the orientation ratio of the (111) plane in approximately constant increments from the outer circumferential surface side to the inner circumferential surface side of the cylindrical sputtering target material. As a result, it was found that the sputtering velocity was about the same on the inner circumferential surface side where the (111) plane had a high and high hardness and the outer circumferential surface where the (111) plane had a low orientation rate and a low hardness.

This invention is based on the said knowledge discovered by the inventor.

One Embodiment of the Invention

(1) cylindrical sputtering target material

Hereinafter, the cylindrical sputtering target material which concerns on one Embodiment of this invention is demonstrated using FIG. 1 is a view showing a cylindrical sputtering target material 20 according to the present embodiment, (a) is a perspective view of a cylindrical sputtering target material 20, and (b) is a cross sectional view of the cylindrical sputtering target material 20.

As shown in Fig. 1, the cylindrical sputtering target material 20 is a metal sputtering target material having a cylindrical shape with both ends open. The cylindrical sputtering target material 20 has, as an example, an outer diameter of 100 mm or more and 200 mm or less, a thickness of 5 mm or more and 40 mm or less, and a length in the major axis direction of 200 mm or more and 5000 mm or less. The metal constituting the cylindrical sputtering target material 20 is oxygen-free copper (OPC: Oxygen-Free Copper) having a purity of 3N (99.9%) or more.

In addition, the cylindrical sputtering target material 20 is configured such that the hardness gradually increases from the outer circumferential surface 21 side toward the inner circumferential surface 22 side. When this is shown by Vickers hardness, the outer peripheral surface 21 side is 75 HPa or more and 80 HPa or less, for example, and the inner peripheral surface 22 side is 95 or more HV or less, for example. The Vickers hardness is defined by the ratio of the load of the indenter when the diamond indenter with a large angle of about 136 degrees is pressed into the sample surface, and the ratio of the surface area of the recess formed in the sample surface. Value.

Herein, the hardness gradually increasing from the outer circumferential surface 21 side toward the inner circumferential surface 22 side includes the case where the hardness is distributed in a constant increase amount from the outer circumferential surface 21 side toward the inner circumferential surface 22 side, Even if the increase is not constant, it includes a case where it is increasing substantially or a case where it is gradually increasing.

Moreover, the cylindrical sputtering target material 20 is comprised so that the orientation ratio of the (111) surface may gradually increase toward the inner peripheral surface 22 side from the outer peripheral surface 21 side. The orientation ratio of the (111) plane is, for example, 10% or more and 15% or less on the outer peripheral surface 21 side, and 20% or more and 25% or less on the inner peripheral surface 22 side, for example. Moreover, the orientation ratio of (111) plane is a value calculated | required from the measurement intensity ratio of each peak which shows the various crystal plane obtained by X-ray diffraction. The measured intensity of each peak is used by correcting, for example, the standard intensity of the peak of the crystal plane corresponding to each peak. For the standard strength, for example, the value described in the PCB card number 40836 is used.

Specifically, as shown in the following equation (1), the sum of the measured intensity of each peak by X-ray diffraction divided by the standard intensity of the peak of the crystal plane corresponding to each peak described in BC Card No. 40836, respectively. The value obtained by formulating the denominator, the value obtained by dividing the measured intensity of the peak of the (111) plane by the X-ray diffraction, and the standard intensity of the peak of the (111) plane described in the PCB card number 40836 by the formula (111) Let it be the orientation ratio of the plane.

[Number 1]

Herein, the orientation ratio of the (111) plane gradually increases from the outer circumferential surface 21 side toward the inner circumferential surface 22 side, so that the orientation ratio of the (111) plane from the outer circumferential surface 21 side toward the inner circumferential surface 22 side is increased. In addition to including the case where it is distributed in a constant increase amount, it includes the case where it increases substantially, or when it increases gradually, even if it is not constant.

Moreover, the cylindrical sputtering target material 20 is comprised so that the crystal grain diameter from the outer peripheral surface 21 side to the inner peripheral surface 22 side may be 100 micrometers or less, More preferably, it is 50 micrometers or more and 100 micrometers or less. In addition, the said crystal grain size is a value calculated | required by the "comparison method" of the "new product crystal grain size test method" prescribed | regulated to JIS H0501.

The cylindrical sputtering target material 20 thus constructed is preferably manufactured by expansion drawing, for example, as described above, in order to reduce production costs. However, in the expansion drawing process, the hardness gradually increases from the outer circumferential surface 21 side toward the inner circumferential surface 22 side. Increasing the hardness makes it less likely to cause a collision cascade, i.e., a collision chain of copper atoms, caused by the collision of ions with the copper atoms during sputtering. In other words, on the inner circumferential surface 22 side with increased hardness, the movement of the copper atoms bounced by the ions is prevented by defects such as grain boundaries and dislocations, and it is difficult for the copper atoms to be concentrated together. The chain is inhibited.

As a result, in the conventional cylindrical sputtering target material, the problem that the sputtering speed of the inner peripheral surface side becomes slow compared with the outer peripheral surface side has arisen. Here, the sputtering rate means the amount of atoms released from the target material per unit time by the sputtering of ions or the like. The amount of atoms released per unit time, i.e., the sputtering rate, may be expressed by, for example, the film thickness of the sputtering film formed per unit time, as described later.

Therefore, in this embodiment, the orientation ratio of the (111) surface of the cylindrical sputtering target material 20 was changed as mentioned above. The (111) plane is the closest plane of copper, and is a crystal orientation in which copper atoms easily protrude out of the cylindrical sputtering target material 20 due to collision of ions during sputtering. Therefore, by increasing the orientation ratio of the (111) plane to the inner circumferential surface 22 side, which is harder than the outer circumferential surface 21 side, the decrease in the sputtering speed due to the inhibition of the collision chain of the copper atom is protruded to the outside of the copper atom. This can be offset by an increase in sputter rate due to an increase in amount. That is, the difference in the sputtering speed from the outer peripheral surface 21 to the inner peripheral surface 22 can be reduced. Alternatively, a substantially constant sputter speed can be obtained from the outer circumferential surface 21 to the inner circumferential surface 22, for example, by completely eliminating the difference in the sputter speed from each other.

In the present embodiment, the crystal grain size of the cylindrical sputtering target material 20 is kept within a predetermined range as described above so as not to coarsen the crystal grains. In experience, it is known that abnormal discharge easily occurs during sputtering when the grain size exceeds 100 µm. In this embodiment, since the crystal grain diameter is 50 micrometers or more and 100 micrometers or less, abnormal discharge can be suppressed.

(2) Manufacturing method of cylindrical sputtering target material

Next, the manufacturing method of the cylindrical sputtering target material 20 which concerns on one Embodiment of this invention is demonstrated using FIG. 2 is a cross-sectional view showing the shape of expansion pipe drawing for manufacturing the cylindrical sputtering target material 20 according to the present embodiment.

The cylindrical sputtering target material 20 can be manufactured with the extruded tube 9 made of copper shown in FIG. 2, for example. The extruded tube 9 is formed by, for example, casting a billet (not shown) made of oxygen-free copper having a purity of 3 N or more, and molding the billet by a hot extrusion method. At this time, for example, the outer diameter of the extruded tube 9 is molded into a cylindrical shape of 140 mm or more and 160 mm or less and the flesh thickness of 25 mm or more and 35 mm or less.

Subsequently, as shown in Fig. 2, for example, a rod 15r having a tapered cylindrical shape plug 15p at its end is provided with an extruded tube 9. Insert into the tube. Next, in the state where the expansion plug 15p is fixed, the extruded pipe 9 is pulled from the small diameter side of the expansion plug 15p toward the larger diameter side, and the outer diameter is reduced at a expansion ratio of, for example, 5% or more and 15% or less. Obtained expanded tube 10. In addition, when the expansion ratio (R) (%) is the outer diameter of the extruded pipe 9 before expansion, D1 (mm), and the outer diameter of the expansion pipe 10 after expansion pipe drawing is D2 (mm), the following equation (2) ),

R = ((D2-D1) / D1) x 100... (2)

It is a value obtained by.

Next, the expansion pipe 10 after expansion pipe drawing is subjected to heat treatment at a temperature of 450 ° C. to 600 ° C., for example, until the whole becomes a substantially uniform temperature, and processing deformation by expansion pipe drawing. The recrystallization of the tissue of the expansion tube 10 which received the back is aimed at. Therefore, when the size of the expansion pipe 10 becomes large, the time of heat processing required for recrystallization becomes long. After that, the expansion pipe 10 is cut out to a predetermined length, and the outer peripheral surface 11 and the inner peripheral surface 12 are subjected to machining such as mirror polishing.

The cylindrical sputtering target material 20 is manufactured by the above.

As described above, in the expansion pipe 10 after expansion pipe drawing, the hardness of the inner circumferential surface 12 side is higher than that of the outer circumferential surface 11 side. On the inner circumferential surface 12 side, in addition to the tensile stress in the axial direction and the compressive stress in the radial direction, it is generated between the expansion pipe plug 15p and the inner circumferential surface 12 of the extruded pipe 9. This is because shear stress acts by friction.

On the other hand, if the expansion ratio is largely determined, the structure control such as the adjustment of the (111) plane and the crystal grain size in the expansion pipe 10 can be easily performed, and the orientation ratio and the crystal grain size of the predetermined (111) plane can be easily controlled. This is easy to get.

Thus, in the present embodiment, the expansion ratio is, for example, 5% or more to improve the controllability of the orientation ratio of the (111) plane and the crystal grain size. Thereby, the orientation ratio and crystal grain size of a predetermined (111) plane can be obtained. As described above, the expansion ratio is, for example, 15% or less, and the occurrence of cracks due to excessive expansion of the expansion pipe 10 is suppressed. Such pipe cracks are particularly likely to occur on the inner circumferential surface 12 and cause leakage of cooling water or the like supplied into the cylinder of the cylindrical sputtering target material 20 during sputtering, or abnormal discharge during sputtering. .

In addition, in the heat treatment which calls for recrystallization of the expansion pipe 10, if the temperature of the heat treatment is too low, sufficient recrystallization does not occur. If the temperature is too high, coarsening of the crystal grains proceeds. In this embodiment, since the temperature of heat processing was made into 450 degreeC or more, for example, recrystallization can fully be accelerated | stimulated. Moreover, since temperature was made 600 degrees or less, for example, excessive coarsening of a crystal grain can be suppressed. As a result, the grain size can be suppressed within a predetermined range.

As described above, in the present embodiment, a high-quality inexpensive cylindrical sputtering target material 20 can be manufactured in which a difference in sputtering speed is suppressed while applying a pipe drawing process with low production cost.

(3) Film deposition method using cylindrical sputtering target material

Next, the method of forming a sputtering film by sputtering using the cylindrical sputtering target material 20 which concerns on one Embodiment of this invention is demonstrated using FIG.

Fig. 3 is a schematic explanatory view showing the shape of sputtering using the cylindrical sputtering target material 20 according to the present embodiment, wherein (a) is an oblique perspective view of the sputtering device 25 on which the cylindrical sputtering target material 20 is mounted. 3B is a cross-sectional view of the cylindrical sputtering target material 20. In addition, the sputtering apparatus 25 shown in FIG. 3 is an example to the last, The cylindrical sputtering target material 20 can be attached to and used in various other sputtering apparatuses.

As shown in Fig. 3, the sputtering is performed in the sputtering apparatus 25 under an inert gas atmosphere such as, for example, argon (Ar) gas. In the vicinity of the bottom part in the sputtering apparatus 25, the board | substrate S used as a film-forming object is arrange | positioned as the upper surface. Moreover, you may arrange | position several board | substrate S in the sputtering apparatus 25, and may carry out the batch process or continuous process of these board | substrates S. FIG.

Above the board | substrate S, the cylindrical sputtering target material 20 is arrange | positioned so that the long axis may become horizontal with the upper surface of the board | substrate S. FIG. That is, the outer peripheral surface 21 which faces downward of the cylindrical sputtering target material 20 is arrange | positioned so that the upper surface of the board | substrate S may be opposed. The cylindrical sputtering target material 20 is rotatably supported about the center axis by the rotation mechanism not shown in the figure.

As shown in Fig. 3B, a cylindrical magnet 23 is inserted into the cylinder of the cylindrical sputtering target material 20 so as to contact the inner circumferential surface 22. The cylindrical magnet 23 is, for example, a flow passage 24 through which a coolant such as cooling water, an organic solvent, and dry air flows. By supplying a coolant into the flow path 24, the temperature rise of the cylindrical sputtering target material 20 can be suppressed at the time of sputtering.

In this state, a negative high voltage is applied to the cylindrical sputtering target material 20 while the cylindrical sputtering target material 20 is rotated in the circumferential direction as shown in FIG. Discharge power is input to S) so that a positive high voltage is applied. As a result, plasma discharge occurs mainly between the cylindrical sputtering target material 20 and the substrate S, and argon (Ar +), which has become positive ions, is formed on the outer circumferential surface 21 of the cylindrical sputtering target material 20. In particular, it collides with the lower surface facing the board | substrate S. FIG. The magnet 23 inserted into the cylindrical sputtering target material 20 attracts argon ions to further promote the collision of argon ions.

The copper atoms constituting the cylindrical sputtering target material 20 due to the collision of argon ions are bounced off from a predetermined position, so that they are protruded out of the cylindrical sputtering target material 20 (sputtered) and attached to the upper surface of the substrate S. do. By continuing the predetermined time sputtering, copper is deposited on the upper surface of the substrate S at a predetermined sputtering speed.

At this time, as shown in Fig. 3 (a), the substrate S is moved at a predetermined speed in the horizontal direction to pass the position just below the cylindrical sputtering target material 20 where copper is more likely to be deposited. The copper film is formed on the upper surface of the substrate S. By constant or varying the moving speed of the substrate S, a sputtering film such as a copper film having a uniform film thickness or a copper film having a predetermined film thickness distribution can be formed.

On the other hand, as described above, the cylindrical sputtering target material 20 rotates in the circumferential direction, and the entire surface is sputtered substantially evenly from the outer circumferential surface 21 side toward the inner circumferential surface 22 side, and the erosion of the surface proceeds. At this time, as the erosion proceeds toward the inner circumferential surface 22 side as described above, that is, as the flesh thickness of the cylindrical sputtering target material 20 gradually decreases by use, the hardness of the cylindrical sputtering target material 20 increases and the copper atom is increased. The collision chain of is inhibited. On the other hand, the orientation ratio of the (111) plane also increases to increase the amount of protruding copper atoms. As a result, both effects are canceled, and the difference in the sputtering speed from the outer circumferential surface 21 to the inner circumferential surface 22 can be reduced, or a substantially constant sputtering speed can be obtained.

In addition, although the surface area of the cylindrical sputtering target material 20 decreases with progress of erosion at this time, it does not need to consider the influence on sputter speed by this substantially. The plasma discharge is generated in an extremely narrow region near the opposing surface of the cylindrical sputtering target material 20 with the substrate S. As shown in FIG. Even if the surface area of the entire cylindrical sputtering target material 20 is slightly reduced by erosion, the surface area exposed to the plasma discharge hardly varies. Since copper atoms are mainly emitted only from a narrow area exposed to this plasma discharge, the influence on the sputter rate by erosion is negligible.

For this reason, in order to keep a sputter speed substantially constant, the increase amount of the orientation ratio of the (111) surface may be decided mainly considering only the increase amount of the hardness of the cylindrical sputtering target material 20 as mentioned above.

In addition, even if the original size itself of the cylindrical sputtering target material 20 is large and small in various other cases, it is considered that there is little influence on the sputtering speed as mentioned above. Thus, for example, in the cylindrical sputtering target material 20 having an outer diameter of 100 mm or more and 200 mm or less, flesh thickness of 5 mm or more and 40 mm or less, and the length in the major axis direction of 200 mm or more and 5000 mm or less, a substantially constant sputtering speed is obtained. .

As mentioned above, in the cylindrical sputtering target material 20, the difference in the sputtering speed from the new state until it can no longer be used is reduced, and sputtering characteristics with little change with time can be obtained. Therefore, the film thickness of the sputtering film is also substantially constant at a constant sputtering time, and a sputtering film having a small characteristic difference can be formed between the individual substrates S.

Moreover, in the whole cylindrical sputtering target material 20, since the difference of the sputter | spatter speed is reduced, it is also possible to delay the replacement time of a target material, and to raise a utilization rate. In addition, the processing time and the like for the individual substrates S can be set to be substantially constant, and the throughput and the like of the sputtering device 25 can be improved. Therefore, the cost of the production process can be reduced.

The substrate S on which the sputtering film is formed as described above is used as various wiring boards after the wiring structure is formed by patterning the sputtering film with a desired wiring pattern, for example.

(4) Structure of thin film transistor

As mentioned above, the sputtering film formed using the cylindrical sputtering target material 20 is used for wiring materials in various wiring boards including thin film transistors used for liquid crystal display devices and the like.

Here, the thin film transistor shown in FIG. 4 is an example of the wiring board which has a board | substrate and the wiring structure formed on the board | substrate, and at least one part of wiring structure consists of the sputtering film formed using the cylindrical sputtering target material 20 mentioned above. The structure of 40 is demonstrated. 4 is a schematic cross-sectional view of the thin film transistor 40 according to the present embodiment.

As shown in FIG. 4, the thin film transistor 40 includes, for example, a glass substrate 48, a gate electrode 47 formed on the glass substrate 48, and a source electrode formed on the gate electrode 47. 41s) and drain electrodes 41d (hereinafter also referred to as source-drain electrodes 41s and 41d). These electrodes 47, 41s, 41d are formed on the glass substrate 48 for each thin film transistor 40 by patterning using, for example, wet etching or dry etching. For example, it is covered with the protective film 49 which consists of silicon nitride (SiI). Alternatively, the glass substrate 48 may be formed such that the plurality of thin film transistors 40 are arranged in an array shape.

The gate electrode 47 formed on the glass substrate 48 is made of copper (Cu) or the like, for example. A gate bus line made of copper or the like and not shown in the drawing is connected to the gate electrode 47.

On the gate electrode 47, for example, a gate insulating film 46 made of silicon nitride and a semiconductor film 44 made of amorphous silicon (? -Si) are sandwiched between the source and drain electrodes ( A laminated structure molded into a predetermined pattern including 41s and 41d) is formed. That is, on the semiconductor film 44, for example, the contact films 43s and 43d made of amorphous silicon (n + -α-Si) doped with phosphorus (P) or the like, and molybdenum or titanium The barrier films 42s and 42d made of (Ti) and the like and the source-drain electrodes 41s and 41d made of pure copper and the like are provided in this order. The channel length between the source and drain electrodes 41s and 41d is, for example, about 10 μm.

A source bus line, which is mainly made of pure copper or the like and is not shown in the drawing, is connected to the source electrode 41s, for example. A transparent electrode 45 for driving a liquid crystal display device or the like is connected to the drain electrode 41d.

Mainly, the wiring structure according to the present embodiment is constituted by the source-drain electrodes 41s and 41d, the source bus lines, the transparent electrodes 45, the gate electrodes 47, the gate bus lines, and the like. At least a part of such a wiring structure, for example, a source bus line made of pure copper (Cu), a gate bus line, or the like is made of a sputtering film formed using the cylindrical sputtering target material 20.

The sputtering film constituting at least a part of the wiring structure as described above is formed using the cylindrical sputtering target material 20 in which the difference in the sputtering speed is reduced, so that a substantially homogeneous sputtering film is provided in each of the elements. The thin film transistor 40 can be obtained with a small difference in characteristics between the two transistors.

In addition, since there are few changes in the sputtering characteristics over time, the utilization rate of the target material can be increased, the cost of the production process can be reduced, and the cheaper thin film transistor 40 can be obtained.

In addition, the structure of the thin film transistor which can introduce | transduce the sputtering film using the cylindrical sputtering target material 20 is not limited to what was described above. For example, the source-drain electrode may be provided with the laminated structure which consists of copper alloy etc. as well as said pure copper. The gate electrode may also be made of, for example, copper as well as copper alloy. In such a configuration, a copper alloy such as copper-manganese (Cu-Mn) may be used as the barrier film.

As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the said Example, A various change is possible in the range which does not deviate from the summary.

(Example)

Next, Examples 1-5 which concern on this invention are demonstrated with Comparative Examples 1-4, referring Table 1 below.

Table 1

(1) Production of evaluation sample

First, a billet made of oxygen-free copper having a purity of 4N (99.99%) was cast, and an extruded tube having an outer diameter of 150 mm and a flesh thickness of 30 mm was formed by the hot extrusion method as in the above embodiment. Next, as in the above embodiment, the tube was expanded to form a tube. At this time, as shown in Table 1, in Examples 1-5 and Comparative Examples 1-4, it set it as the different expansion ratio, respectively. For example, in Example 1, the expansion ratio was 10%, and the expansion pipe of 165 mm in outer diameter and 25 mm in thickness was formed.

Subsequently, heat treatment was performed on each expansion pipe as in the above embodiment. At this time, as shown in Table 1, in Examples 1-5 and Comparative Examples 1-4, respectively, using different temperature, the time of heat processing was 180 minutes. Four predetermined | prescribed places were cut out in the major axis direction from each expansion pipe produced in this way, and four sets of evaluation samples were produced about all of Examples 1-5 and Comparative Examples 1-4. Each evaluation sample was cut out from the approximate center part of the long axis except the both ends.

(2) measurement of evaluation samples

Next, each of the evaluation samples of Examples 1 to 5 and Comparative Examples 1 to 4 was used one by one, and the expansion of crack crack irradiation and grain size evaluation, Vickers hardness test, crystal orientation measurement, and sputter velocity measurement shown below were used. Was done. At this time, as shown in FIG. 5, the area | region which extends from the outer peripheral surface 31 to the inner peripheral surface 32 of each evaluation sample 30 is divided into 5 area | regions from e to a in radial direction, and each area | region Each of the above measurements was carried out. That is, in Example 1 having a flesh thickness of 25 mm, each measured value was obtained in the regions e to a divided by 5 mm intervals in the radial direction.

(Expansion crack investigation and grain size evaluation)

The results of the expansion crack investigation and the grain size evaluation will be described below. First, mirror polishing was performed on each set of evaluation samples of Examples 1 to 5 and Comparative Examples 1 to 4 to perform etching. Next, the structure of each of the regions e to a was observed with an optical microscope, and the results of measurement of the presence of expansion cracks and the grain size were obtained. About the expansion crack, it was determined that there was even one crack within the range of 20 mm width in the circumferential direction, and it was determined that there was no crack. In addition, the grain size (μm) was measured based on the "comparative method" of "the new product crystal grain size test method" prescribed | regulated to JIS H0501.

As shown in Table 1, in Examples 1-5, there was no expansion crack. In contrast, in Comparative Examples 1 to 4, expansion cracks were generated in Comparative Example 1 and Comparative Example 4 having a large expansion ratio. Therefore, Comparative Example 1 and Comparative Example 4 do not satisfy the quality as a cylindrical sputtering target material.

In addition, as shown in Table 1, in Examples 1-5, all the crystal grain diameters were 100 micrometers or less. Therefore, in Examples 1-5, the occurrence frequency of abnormal discharge at the time of sputtering is expected to be low. On the other hand, the crystal grain sizes measured for Comparative Examples 2 and 3, which had no expansion cracks, exceeded 100 µm, especially in Comparative Example 2 having a high heat treatment temperature.

(Vickers hardness test)

Below, the result of the Vickers hardness test is demonstrated. With respect to one set of evaluation samples of Examples 1 to 5 and Comparative Examples 1 to 4, a Vickers hardness test, and more specifically, a micro Vickers hardness test was performed in which a load applied by an indenter was reduced and microscopic crystals and the like could be measured. . At this time, it measured 5 times in each area | region e-a of each evaluation sample, and made the average value into the Vickers hardness (Hk) in the area | region.

As shown in Table 1, also in the evaluation samples in any of Examples 1 to 5, the Vickers hardness gradually increased from the outer peripheral surface side toward the inner peripheral surface side. In particular, in Examples 1 to 3, the outer circumferential side was in the range of the value specified above, that is, the outer circumferential side was in the range of 75 to 80 hPa, and the inner circumferential surface was in the range of 95 to 100 hV. Also in Comparative Example 2 and Comparative Example 3, although deviated from the prescribed values, the tendency of the hardness to increase from the outer peripheral surface side toward the inner peripheral surface side was all the same.

Crystal orientation measurement

The result of the crystal orientation measurement is described below. About one set of evaluation samples of Examples 1-5 and Comparative Examples 1-4, the peak intensity which shows various crystal planes was measured using the X-ray diffraction apparatus. Subsequently, the measurement intensity of each peak and the standard intensity of each peak described in the PCB card number 40836 were substituted into the above formula (1) to obtain an orientation ratio (%) of the (111) plane.

As shown in Table 1, in Examples 1-5, the orientation rate of the (111) plane gradually increased from the outer peripheral surface side toward the inner peripheral surface side. More specifically, also in all the evaluation samples of Examples 1-5, the outer peripheral surface side could be in the range of 10% or more and 15% or less, and the inner peripheral surface side could be in the range of 20% or more and 25% or less. In contrast, in Comparative Example 2, the orientation ratio of the (111) plane became substantially constant from the outer circumferential surface side toward the inner circumferential surface side, and in Comparative Example 3 in which the expansion ratio was small, the orientation ratio of the (111) plane on the outer circumferential surface side This has become very small.

(Sputter speed measurement)

Below, the result of sputtering speed measurement is demonstrated. Each set of evaluation samples of Examples 1 to 5 and Comparative Examples 1 to 4 was attached to the same sputtering apparatus as the above embodiment, and the sputtering speed of each evaluation sample was measured. Specifically, a sputtering film was formed on a glass substrate by argon gas, sputtering for 3 minutes with a discharge power of 33 kW. Then, the film thickness of this sputtering film was measured with the laser microscope, and converted into the film thickness formed into a film for about 1 minute, and this was made into the sputter speed (n / mI).

As shown in Table 1, in Examples 1-5, the substantially constant sputter speed from the outer peripheral surface to the inner peripheral surface was obtained. Although not shown in Table 1, in Comparative Example 1 and Comparative Example 4 having an expansion ratio of 5% or more, a substantially constant value was obtained for the sputtering speed. On the other hand, in Comparative Example 2 in which the orientation ratio of the (111) plane was substantially constant and Comparative Example 3 in which the orientation ratio of the (111) plane was small from the outer circumferential side, the sputtering speed was lowered from the outer circumferential side toward the inner circumferential side. It could be observed.

As described above, in Examples 1 to 5, good results were obtained regarding any of the expansion crack, the grain size, and the sputtering speed. At this time, the difference in Vickers hardness between the outer circumferential surface side and the inner circumferential surface side is at least 75 HＶ or more and 80 HＶ or less from the outer circumferential side, or 95 HＶ or more and 100 HＶ or less from the inner circumferential side, or the (111) plane between the outer circumferential side and the inner circumferential side. When the difference in the orientation ratios was at least 10% and 15% or less on the outer circumferential surface side and 20% or more and 25% or less on the inner circumferential surface side, it was found that a substantially constant sputter speed was obtained from the outer circumferential surface to the inner circumferential surface.

In addition, it was found that the Vickers hardness and the orientation ratio of the (111) plane are obtained by setting the expansion ratio to 5% or more. On the other hand, when the expansion ratio was 15% or less, the expansion crack was suppressed, and the heat treatment temperature after the expansion pipe drawing was controlled to be 450 ° C. or more and 600 ° C. or less.

9: extruded pipe
10: expansion
11, 21, 31: outer circumference
12, 22, 32: inner circumference
15p: expansion plug
15r: load
20: cylindrical sputtering target material
23: magnet
24: Euro
25: sputtering device
30: Evaluation Sample
40: thin film transistor
41: source electrode
42: drain electrode
43: auxiliary electrode film
44: electrode film
45: barrier film
46: n type semiconductor film
47: protective film
48: semiconductor film
49: gate insulating film
50: gate electrode
51: glass substrate
S: Substrate

Claims

As a cylindrical sputtering target material formed of oxygen free copper having a purity of 3 N or more and having a cylindrical shape,
While the hardness gradually increases from the outer circumferential side toward the inner circumferential surface side,
A cylindrical sputtering target material, wherein the orientation ratio of the (111) surface gradually increases from the outer peripheral surface side toward the inner peripheral surface side.

The method of claim 1,
Even if the flesh thickness decreases gradually by the use of the cylindrical sputtering target material, the sputter speed of the cylindrical sputtering target material becomes constant.
The decrease in the sputtering speed of the cylindrical sputtering target material due to the gradually increasing hardness from the outer circumferential surface side toward the inner circumferential surface side, and the orientation ratio of the (111) plane gradually toward the inner circumferential surface side from the outer circumferential surface side. A cylindrical sputtering target material, characterized in that the increase in the sputtering speed of the cylindrical sputtering target material by increasing is canceled out.

The method according to claim 1 or 2,
The hardness is Vickers hardness,
Vickers hardness of the outer peripheral surface side is 75HPa or more and 80HPa or less, Vickers hardness of the inner peripheral surface side is 95HPa or more and 100HPa
A cylindrical sputtering target material, characterized in that.

The method according to any one of claims 1 to 3,
The orientation ratio of the (111) plane on the outer peripheral surface side is 10% or more and 15% or less, and the orientation ratio of the (111) plane on the inner peripheral surface side is 20% or more and 25% or less
A cylindrical sputtering target material, characterized in that.
(However, the orientation ratio of the (111) plane,
The sum of the values obtained by dividing the measured intensity of each peak by X-ray diffraction with the standard intensity of the peak of the crystal plane corresponding to each of the peaks described in BC Card No. 40836 as the denominator,
The value obtained by dividing the measured intensity of the peak of the (111) plane by X-ray diffraction with the standard intensity of the peak of the (111) plane described in BC Card No. 40836 is obtained from the formula of using a molecule.)

The method according to any one of claims 1 to 4,
A cylindrical sputtering target material, wherein the crystal grain size is in a range of 50 μm or more and 100 μm or less.

The method according to any one of claims 1 to 5,
A cylindrical sputtering target material, characterized by being formed by expansion pipe drawing and heat treatment on an extruded pipe.

Substrates,
A wiring structure formed on the substrate
Respectively,
At least a part of said wiring structure is a wiring board formed using the sputtering film formed using the cylindrical sputtering target material of Claim 1.

A substrate;
A wiring structure formed on the substrate, the wiring structure including a source electrode and a drain electrode;
Respectively,
At least part of the wiring structure is a thin film transistor comprising a sputtering film formed using the cylindrical sputtering target material of claim 1.