JP2000323434A - Sputtering target, wiring film, and electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce with superior reproducibility in-plane uniformity of a TaN film to be used as a barrier layer of a semiconductor element by a method wherein the peak intensity in a specified direction measured by an X rays diffraction method is specified on the surface of a sputtering target composed of high pure TaN. SOLUTION: A sputtering target is one composed of high pure TaN, and a ratio of the peak intensity on (111) plane measured by an X rays diffraction method on a target surface to the gross sum of the peak intensity on the other crystal planes, namely a peak intensity ratio of (111)/ (110)+(101)+(111)+(201)+(300)+(211)+(220)+(112)+(311)} is in the range of 0.05 to 0.20. Thus, it becomes possible to fairly increase the film thickness distribution of a TaN film formed by using it. Here, on a surface (target plane) of a TaN target, a plurality of crystal direction measured by the X rays diffraction method exist, and releasing angles of particles flying by sputtering the (111) plane thereamong are narrowed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputter target suitable for forming a barrier material for a Cu wiring, a wiring film and an electronic component using the same.

[0002]

2. Description of the Related Art In recent years, the semiconductor industry represented by LSI has been rapidly advancing. 2. Description of the Related Art In semiconductor devices such as high-speed logic, as the degree of integration, reliability, and functionality increases, the precision required for microfabrication technology has been increasing. With the increase in density and speed of such integrated circuits, the width of metal wiring formed mainly of Al or Cu is becoming 1/4 μm or less.

On the other hand, in order to operate an integrated circuit at high speed, it is essential to reduce the resistance of Al wiring and Cu wiring. In the conventional wiring structure, it is common to reduce the wiring resistance by increasing the height of the wiring. But,
In semiconductor devices with higher integration and higher densities, the coverage of the insulating film formed on the wiring becomes worse when the conventional laminated structure is used, and the yield naturally lowers. There is a need to improve the technology itself.

Therefore, application of a dual damascene (DD) wiring technique, which is different from the conventional wiring technique, is being studied. The DD technique means that a metal mainly composed of Al or Cu as a wiring material is formed on a wiring groove previously formed in a base film by using a sputtering method or a CVD method, and is poured into the groove by heat treatment (reflow). , CMP (Chemical
This is a technique for removing excess wiring metal by mechanical polishing or the like.

[0005] As a wiring material used for a semiconductor device as described above, C has a lower resistivity than Al.
Since u is becoming mainstream, Cu wiring is generally used in semiconductor devices such as logic. An advantage of the Cu wiring is that it has excellent electromigration resistance as compared with the Al wiring. However, on the other hand, metals such as Cu, Au, and Fe are lattice-diffused in silicon, so that the diffusion speed is high, and there is a concern that the life of minority carriers may be shortened when they enter silicon.

[0006] For this reason, when a Cu wiring is applied, it is essential to provide a barrier metal layer for preventing the diffusion of Cu into Si. Here, TiN has been used as a barrier metal for semiconductor elements. Recently, TaN has been proposed as a barrier material for Cu wiring, and TaN is effective for preventing diffusion of Cu into Si. Is becoming apparent.

Therefore, the barrier layer for Cu wiring is made of TaN.
Are moving in the direction of applying. As a method of forming such a TaN film as a barrier layer, as in the case of the conventional TiN film, chemical sputtering using a mixed gas of Ar and N ₂ using a Ta target, that is, Ta target using N ₂ ⁺ ions together with Ar Chemical sputtering, which bombards the surface and flies as a compound of Ta and N ₂ ions (TaN), is mainly applied.

[0008]

However, the TaN obtained by the conventional chemical vapor deposition using a Ta target has a problem.
For the film, use the above-mentioned DD wiring to satisfy the film homogeneity required for next-generation logic, etc., where the aspect ratio of the wiring groove at that time is expected to be 1/4 or more. Is in a very difficult situation and is already reaching its limits.

For example, it is required to control the in-plane uniformity of the film to 5% or less on an 8-inch Si wafer. In the case of conventional phase sputtering using a Ta target,
A TaN film satisfying such conditions cannot be obtained with good reproducibility.

The present invention has been made to address such a problem, and it is possible to reduce the in-plane uniformity of a TaN film used as a barrier layer of a semiconductor element, for example, to 5% or less with good reproducibility. The purpose of the present invention is to provide a sputter target, and by using such a sputter target, a wiring film that satisfies high definition and high reliability required for next-generation logic and the like,
It is another object of the present invention to provide an electronic component using such a wiring film.

[0011]

Means for Solving the Problems The present inventors have conducted various studies to solve the above problems, and as a result, have found that it is effective to use a TaN target. Furthermore, Ta
As a result of investigating the relationship between the crystal orientation of the N target surface and the emission angle of sputtered particles, it was found that the emission angle of particles flying by sputtering the (111) plane was as narrow as 45 ° or less. Therefore, by controlling the ratio of the peak intensity of the (111) plane to the sum of the peak intensities of the other crystal planes within an appropriate range, in-plane uniformity of the TaN film, which could not be achieved conventionally, can be realized. Was found.

The present invention has been made based on such knowledge, and the sputter target of the present invention is a sputter target made of high-purity TaN, as described in claim 1, wherein The peak intensity of the (111) plane measured by the X-ray diffraction method is (111) / ｛(110)
+ (101) + (111) + (201) + (300) + (211) + (220) +
The intensity ratio of (112) + (311)｝ is in the range of 0.05 to 0.20.

[0013] The sputter target according to the present invention further has a peak intensity ratio of the (111) plane [(111) / ｛(110) +] over the entire surface of the target.
(101) + (111) + (201) + (300) + (211) + (220) + (1
12) + (311)｝] is within ± 30%.

The sputter target of the present invention is used, for example, by bonding it to a backing plate. At this time, the bonding between the sputter target and the backing plate is performed by the solder bonding described in claim 4 or the diffusion bonding described in claim 5.

According to a sixth aspect of the present invention, there is provided a wiring film including a TaN film formed by using the above-described sputtering target of the present invention.
In the wiring film of the present invention, for example, the TaN film is used as a barrier material for the Cu film.

An electronic component according to the present invention is characterized in that it has the above-described wiring film according to the present invention. The electronic component according to the present invention is characterized in that the wiring film includes, for example, a TaN film and a Cu film present thereon. The electronic component of the present invention is, for example, a semiconductor element.

[0017]

Embodiments of the present invention will be described below.

The sputter target of the present invention has a high purity T
aN, a ratio of the peak intensity of the (111) plane measured by X-ray diffraction on the target surface to the sum of the peak intensities of the other crystal planes, that is,
(111) / ｛(110) + (101) + (111) + (201) + (300) +
The peak intensity ratio of (211) + (220) + (112) + (311) 0.0 is 0.0
It is in the range of 5 to 0.20. Incidentally, a TaN in the present invention and (tantalum _{nitride) Ta 1 N 1-x (} x = 0.9~1.0).

Here, on the surface (target surface) of the TaN target, there are many crystal orientations measured by the X-ray diffraction method. Among them, it was found that the (111) plane was sputtered and the emission angle of flying particles was narrow. Therefore, the ratio of the peak intensity of the (111) plane of the target plane to the sum of the peak intensities of the other crystal planes, that is, (111) / ｛(110)
+ (101) + (111) + (201) + (300) + (211) + (220) +
A plurality of T's with different peak intensity ratios of (112) + (311)｝
As a result of evaluation using an aN target, (111) / ｛(11
0) + (101) + (111) + (201) + (300) + (211) + (220)
It has been found that when the peak intensity ratio of + (112) + (311)｝ is in the range of 0.05 to 0.20, it is possible to greatly increase the thickness distribution of the TaN film formed using the peak intensity ratio.

On the surface of the TaN target, (111) / ｛(110) + (101) + (111) +
When the peak intensity ratio of (201) + (300) + (211) + (220) + (112) + (311)｝ is in the range of 0.05 to 0.20, the emission angle of the sputtered particles is, for example, 45 ° or less. Thus, only sputter particles having a vertical component can be deposited on the substrate. Therefore, the resulting Ta
The uniformity of the thickness of the N film can be improved.

From the above, in the sputter target of the present invention, (111) / ｛(110) +
(101) + (111) + (201) + (300) + (211) + (220) + (1
The peak intensity ratio of (12) + (311)｝ is in the range of 0.05 to 0.20. More preferably, the peak intensity ratio at the target surface of the TaN sputtering target is in the range of 0.08 to 0.15.

If the above-mentioned peak intensity ratio on the surface of the TaN target is smaller than 0.05, the radiation angle of the sputtered particles becomes, for example, 45 ° or more, and the vertical component of the sputtered particles is impaired, so that the film thickness distribution is reduced. Further, since a large number of sputter particles are scattered around the substrate, generation of dust increases. On the other hand, when the above-described peak intensity ratio exceeds 0.20, the vertical component increases, but the difference in the sputtering rate between Ta and N increases, so that selective sputtering is performed, and the in-plane uniformity of the film deteriorates. .

The peak intensity of the (111) plane and other crystal planes in the present invention is a value obtained by correcting the maximum intensity value of each peak obtained by X-ray diffraction with a correction intensity value described in a JCPDS card. It refers to That is, for example, the peak intensity of the (111) plane is expressed by the maximum intensity value of the (111) plane /
12 (correction intensity value described on JCPDS card)｝ Table 1 shows a list of the correction intensity values described on the JCPDS card.

[0024]

[Table 1] In the present invention, (111) / ｛(110) +
(101) + (111) + (201) + (300) + (211) + (220) + (1
It is preferable that the variation of the peak intensity ratio of (12) + (311)｝ be within ± 30% on the entire target surface. As described above, by controlling the above-mentioned peak intensity ratio within a certain range for the entire target surface, it is possible to improve the film thickness and film characteristics of the entire TaN film formed using the same. The above-mentioned variation in the peak intensity ratio of the entire target surface is more preferably within ± 20%, particularly preferably within ± 10%.

That is, if the variation in the peak intensity ratio of the entire surface of the TaN target exceeds the range of ± 30%, the uniformity of a semiconductor device using a TaN film formed using the TaN target is adversely affected. . Since current semiconductor devices are produced in units of tens of thousands from an 8-inch Si wafer, variations in the peak intensity ratio on the surface of the TaN target directly affect the wiring film on the Si wafer, and variations in the reliability of each semiconductor device. As a result. For example, a device produced from the edge of a Si wafer has good reliability, but a device produced from the center has a low reliability.

Although the sputter target of the present invention is made of high-purity TaN, it may contain some impurity elements, for example, at the level of a general high-purity metal material. However, it is preferable to reduce the amount of the impurity element in order to reduce the wiring resistance, for example.

The sputter target of the present invention is produced, for example, as follows.

For example, a sintered body is manufactured by using a TaN powder having a purity of about 2N and applying a known sintering method such as a HIP method or a hot press method. The sintering atmosphere is preferably an N ₂ atmosphere. The size of the sintered body is 100 ~ 400mm in diameter
It is preferable to set the degree. When changing the nitrogen content in the target, a mixed powder of TaN powder and Ta powder whose mixing ratio is appropriately adjusted may be used as a starting material.

Next, the above-mentioned sintered body is again heat-treated at a temperature of about 100 to 500 ° C. in a vacuum. By such a heat treatment, (111) / ｛(11
0) + (101) + (111) + (201) + (300) + (211) + (220)
The peak intensity ratio of + (112) + (311)｝ is controlled within the range of 0.05 to 0.20, and the variation of the peak intensity ratio of the entire target surface is controlled within ± 30%. The high-purity TaN material thus obtained is machined and joined to a backing plate made of, for example, Cu or Al.

Here, for example, solder bonding or diffusion bonding is applied to the bonding with the backing plate. When diffusion bonding is applied, the temperature at the time of bonding is preferably set to 600 ° C. or less. This is to prevent plastic deformation of the backing plate. By machining the obtained material to a predetermined size, the sputter target of the present invention can be obtained.

The wiring film of the present invention is a TaN film formed by sputtering using the above-described sputtering target of the present invention.
It has a film. Ta obtained in this way
The N film is excellent in the uniformity of the film thickness and film characteristics, and for example, the film thickness distribution in the film surface can be 5% or less.

Such a TaN film is suitable as a barrier material for a Cu wiring (Cu film or Cu alloy film), for example.
The wiring film of the present invention is formed by, for example, providing a Cu film on the above-described TaN film. Such a wiring film sufficiently satisfies the homogeneity required for the wiring film when, for example, the DD wiring technology is applied.

The wiring film of the present invention described above can be used for various electronic parts typified by semiconductor elements. Specifically, ULSI or VLSI using the wiring film of the present invention
And other electronic components such as SAW devices and TPH. The electronic component of the present invention includes such a semiconductor element, a SAW device, a TPH, and the like.

[0034]

Next, specific examples of the present invention and evaluation results thereof will be described.

Example 1 First, TaN powder having a purity of 2N was mixed in a ball mill for 24 hours, and then six sintered bodies were produced by the HIP method. HIP
Processing conditions are: temperature 1200 ° C, holding time 5 hours, surface pressure 120MP
a. These sintered bodies were subjected to a heat treatment at 400 ° C. for 120 minutes.

Next, each sintered body was machined to a diameter of 3 mm.
A TaN material was manufactured by processing to 20 mm × 10 mm in thickness. Thereafter, these TaN materials were soldered to a Cu backing plate to obtain six types of TaN sputter targets. By controlling the processing conditions and heat treatment conditions (temperature and time), these six types of TaN targets can be used to (111) / ｛(110) + (101) + (111) + (111) + (201) +
The peak intensity ratio of (300) + (211) + (220) + (112) + (311)｝ is changed.

The X-ray diffraction of the target surface was carried out using an XRD apparatus manufactured by Rigaku Co., Ltd., and measured at that time.
The maximum intensity value of the (111) plane peak and other crystal planes ((110), (1
01), (111), (201), (300), (211), (220), (11
2), (311)), using the maximum intensity value of the peak, (111) /
｛(110) + (101) + (111) + (201) + (300) + (211) +
The peak intensity ratio of (220) + (112) + (311)｝ was determined.

Using each of the six types of TaN sputter targets thus obtained, a sputtering method: LTS
Sputtering, back pressure: 1 × 10 ^-5 Pa, sputtering gas: Ar, output: DC 15 kW, sputtering time: 1 min, forming a TaN film on a Si wafer (8 inches) in which wiring grooves were formed in advance. Then, a barrier layer having a thickness of 0.5 μm including the inside of the wiring groove was formed. Thereafter, sputtering was performed using a Cu target under the same conditions as those described above to form a Cu film having a thickness of about 1 μm. After filling this into the wiring groove by reflow treatment, a wiring was formed by CMP.

For these wirings, the in-plane uniformity of the thickness of each barrier layer was measured. The result is expressed as (111) / ｛(110) + (101) + (111) + (201) + on the TaN target surface.
(300) + (211) + (220) + (112) + (311)｝ Table 2 shows the peak intensity ratio and its variation.

[0040]

[Table 2] As is clear from Table 2, the TaN of the present invention of Samples 1 to 4
The barrier layer composed of a TaN film formed using a target has excellent film uniformity, and has a film uniformity of 5% or less as compared with the TaN films formed using the TaN targets of Samples 5 and 6. It has been found that it is possible to improve. By applying a wiring film having such a TaN barrier layer, the product yield can be significantly improved.

[0041]

As described above, according to the TaN sputtering target of the present invention, it is possible to obtain a TaN film having excellent uniformity in film thickness and film characteristics. Therefore, according to the wiring film of the present invention having the TaN film formed by using such a sputter target and the electronic component using the same, it is possible to greatly improve the reliability and the product yield.

[0042]

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Ishigami 8th Shinsugitacho, Isogo-ku, Yokohama, Kanagawa Prefecture Inside Toshiba Yokohama Office (72) Inventor Naomi Fujioka 8th Shinsugitacho, Isogo-ku, Yokohama, Kanagawa 4K029 BA08 BA58 BB02 BD02 DC05 DC22 DC24 4M104 BB04 BB32 DD40 FF18 HH20

Claims (10)

[Claims] 1. A sputter target comprising high-purity TaN, wherein a peak intensity of a (111) plane measured by an X-ray diffraction method on the target surface is (111) / ｛(110) + (1
01) + (111) + (201) + (300) + (211) + (220) + (11
2) A sputter target, wherein the intensity ratio of (311)｝ is in the range of 0.05 to 0.20. 2. The sputter target according to claim 1, wherein a variation in a peak intensity ratio of the (111) plane over the entire surface of the target is within ± 30%. 3. The sputter target according to claim 1, wherein the sputter target is joined to a backing plate. 4. The sputter target according to claim 3, wherein the sputter target and the backing plate are joined by a solder joint. 5. The sputter target according to claim 3, wherein the sputter target and the backing plate are bonded by diffusion bonding. 6. A wiring film comprising a TaN film formed by using the sputter target according to claim 1. 7. The wiring film according to claim 6, wherein the TaN film is a barrier material for a Cu film. 8. An electronic component comprising the wiring film according to claim 6. 9. The electronic component according to claim 8, wherein the wiring film includes the TaN film and a Cu film existing on the TaN film. 10. The electronic component according to claim 8, wherein the electronic component is a semiconductor device.