JPH09209135A - Target for magnetron sputtering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the sticking and deposition of sputtered products even in the case of high output sputtering and to prevent the generation of coarse particles by subjecting the nonerosion parts in a target face to mirror polishing. SOLUTION: The nonerosion parts at the center and periphery of a target sputtered face are finished into mirror faces having 0.01 to 0.09μm surface roughness Ra (where Ra denotes the center line average roughness). Preferably, the whole body of the sputtered face contg. the nonerosion parts is subjected to mirror polishing into 0.1 to 0.09μm surface roughness Ra. Thus, the unstabilization of sputtering at the time of the start of film formation is prevented, and on the other hand, the sticking and deposition of the sputtered products to the nonerosion parts can be evaded. Moreover, the sputtered face side of a backing plate supporting the target is preferably subjected to mirror finishing as well into roughness similar to that of the sputtered face to remove a factor in the causation of coarse particles from the above part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron sputtering target capable of forming a film with few particles for a long period of time.

[0002]

2. Description of the Related Art Generally, it is known that wiring, a barrier film and the like are formed by a magnetron sputtering method in a semiconductor manufacturing process. In this magnetron sputtering method, plasma is generated by using Ar gas as an atmosphere gas, and a magnet is used. The target surface is sputtered while applying a vertical magnetic field to the target surface to form a sputtered film on the surface of a substrate such as a wafer. Since the target used at this time is usually machined from a pure metal plate, an alloy plate, a ceramic plate, etc., its surface roughness Ra (however, Ra represents the center line average roughness, the same applies hereinafter). ) Has a thickness of 0.1 to 1 μm.

When magnetron sputtering is performed using this conventional target, the ring surface except the central portion and the outer peripheral edge portion is sputtered on the sputtering surface of the target, and the central portion and the outer peripheral edge portion are not sputtered. The non-sputtered central portion and the outer peripheral edge portion of the target sputtering surface are usually referred to as non-erosion portions, and the sputtered portion sandwiched between the central portion and the outer peripheral edge portion of the target sputtering surface is generally referred to as the erosion portion. ing. Since the non-erosion portion is not sputtered during the sputtering, a sputtered film is deposited on the non-erosion portion, and the deposit of the sputtered film formed on the non-erosion portion is peeled off and dropped onto a substrate such as a silicon wafer with a diameter of 0.3 μm. It is said that the above coarse particles are generated.

In recent years, a magnetron sputtering device for carrying out this magnetron sputtering method has been used.
As the sputter conditions are becoming more and more severe and the sputter conditions are becoming more and more severe as a result, sputtering the conventional targets above under even more severe conditions results in
A large number of coarse particles having a diameter of 0.3 μm or more were generated during film formation during a short-time operation, which required frequent replacement of the target, and the efficiency of sputtering operation was sometimes rather reduced.

In order to improve this, the surface roughness of the flat ring-shaped erosion portion of the sputter surface is the same as the conventional one.
a: 0.1 to 1 μm, and the surface roughness of the non-erosion portion constituted by the central portion and the outer peripheral edge portion of the remaining sputtering surface is rougher than the surface roughness of the erosion portion Ra: 2 to 5 μm.
A target for magnetron sputtering having a height of m has been proposed. That is, the surface roughness of the non-erosion part of the target is processed to be Ra: 2 to 5 μm, which is coarser than usual, and the sputtered film adhered to the non-erosion part is firmly adhered so as not to fall off, and coarse particles are generated. It suppressed that. Further, it is said that the generation of coarse particles is further prevented by making the corner portion of the outer peripheral edge portion of the non-erosion portion into the R processed surface (see Japanese Patent Laid-Open No. 6-306592).

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The target for magnetron sputtering described in the 592 publication is certainly an excellent target with less generation of coarse particles, but for higher power sputtering, the heat cycle of heating and cooling during sputtering is vigorous, and therefore the target. It is unavoidable that coarse particles are generated due to peeling off and peeling off of the adhered film deposited on the non-erosion part of the above, and it is the current situation that this leads to the end of the service life.

[0007]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, as a result of research to develop a target for magnetron sputtering in which coarse particles are less likely to be generated during film formation even when high-power sputtering is performed, (a) the target surface has a surface roughness Ra. : When the surface is mirror-polished to 0.01 to 0.09 μm, the non-erosion portion is mirror-polished even if a deposit is deposited on the non-erosion portion which is mirror-polished during sputtering. (B) Target side of the sputter surface including non-erosion part, in which coarse particles are prevented from being generated due to peeling and detachment of the adhered film deposited on the non-erosion part It is easier to polish and process the entire surface if the surface roughness Ra is 0.01 to 0.09 μm. (C) If the mirror polishing is applied not only to the sputtering surface side of the target but also to the sputtering surface side of the backing plate of the target, the formation of coarse particles during film formation will be further suppressed. I got the research results.

The present invention has been made on the basis of the above research results. (1) The surface roughness Ra: 0 of the non-erosion portion consisting of the central portion of the target which is not sputtered and the outer peripheral edge portion on the sputtering surface side. 0.01-0.09μ
The target for magnetron sputtering, which is mirror-polished to m, (2) the entire surface of the sputtering surface including the non-erosion portion of the target has a surface roughness Ra: 0.01 to 0.0
Target for magnetron sputtering which is mirror-polished to 9 μm, (3) Surface roughness Ra of the backing plate to which the target is joined Ra: 0.01 to
Mirror-polished to 0.09 μm (1) or (2)
The target for magnetron sputtering described above is characterized.

The magnetron sputtering target of the present invention can be applied to any metal target, but is most preferably any metal target of Ni, Ti, Co and Cu. By polishing or buffing the sputtering surface side of the target and the backing plate with SiC abrasive grains, the surface roughness Ra of the sputtering surface side of the target and the backing plate can be set to 0.01 to 0.09 μm.

If the surface roughness Ra of the target and the backing plate on the sputtering surface side is less than 0.01 μm, the discharge at the start of sputtering becomes unstable and smooth start becomes difficult, which is not preferable.
Is more than 0.09 μm, the deposition of the deposits in the non-erosion portion becomes vigorous and the generation of coarse particles rapidly increases, which is not preferable. Therefore, the surface roughness R on the sputtering surface side of the target and the backing plate is R.
a was set to 0.01 to 0.09 μm. A more preferable range of the surface roughness Ra is 0.03 to 0.06 μm.

If the surface roughness Ra of the erosion portion is a normal surface roughness of 0.1 to 1 μm and only the non-erosion portion has a surface roughness Ra of 0.01 to 0.09 μm, the discharge at the start of sputtering will occur. Will be stable in a short period of time and a smooth start will be possible.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1 As a target, a pure Ti disk having a diameter of 250 mm and a thickness of 10 mm and a purity of 99.999% was prepared.
Furthermore, as a backing plate for cooling, diameter: 350
mm × thickness: Aluminum alloy with dimensions of 15 mm (J
A disk made of IS A5052) was prepared. This pure Ti disc is diffusion-bonded to an aluminum alloy disc to prepare a target substrate composed of a pure Ti disc and an aluminum alloy backing plate.
Sputtering surface side of i disc, non-erosion part of aluminum disc and backing plate made of aluminum alloy were both mirror-polished to a surface roughness Ra: 0.05 μm. The Ti target 2 of the present invention in which the non-erosion portion is mirror-polished to have a surface roughness Ra of 0.05 μm and the surface roughness Ra of the aluminum alloy backing plate is kept to 0.5 μm while the sputter surface side is cut. The entire surface of the pure Ti disk including the non-erosion portion on the sputter surface side and the back surface of the aluminum alloy backing plate on the sputter surface side have surface roughness Ra: 0.
Ti target 3 of the present invention mirror-polished to 05 μm, pure T
The surface roughness Ra of the entire back surface of the i backing plate including the non-erosion portion is mirror-polished to have a surface roughness Ra of 0.05 μm, and the back surface of the aluminum alloy backing plate is left as it is while being cut. The Ti target 4 of the present invention held at 0.5 μm, and the surface roughness of the entire sputtering surface side including the non-erosion portion of the pure Ti backing plate and the surface roughness of the aluminum alloy backing plate on the sputtering surface side as they are cut. Ra: A conventional Ti target held at 0.5 μm was prepared.

The Ti targets 1 to 4 of the present invention and the conventional Ti target were loaded into a DC magnetron sputtering apparatus, and the output was 12 kW, the atmosphere was Ar, the sputtering pressure was 8 mTorr, and the sputtering time was 2 minutes / wafer. Then, the operation of forming a Ti film of 0.5 μm on the surface of a planar circular Si wafer having a diameter of 150 mm is repeated, and the number of particles having a diameter of 0.2 μm or more existing in the Ti film is measured by using a particle counter. Observation was performed by shining light, and the number of Si wafers until the number of particles in the Ti film exceeded 100 / wafer was measured. Table 1 shows the results of these measurements.

[0014]

[Table 1]

Example 2 As a target, a pure Ni disc having a diameter of 250 mm and a thickness of 10 mm and a purity of 99.999% was prepared.
Further, as a cooling backing plate, an aluminum alloy (JIS A5052) disk having the same diameter: 350 mm × thickness: 15 mm as in Example 1 was prepared, and this pure Ni disk was used as an aluminum alloy disk. Diffusion bonding was performed to prepare a target substrate composed of a pure Ni disk and an aluminum alloy backing plate. The non-erosion portion of the pure Ni disk on the sputter surface side of this target substrate and the sputter surface side of the aluminum alloy backing plate were both mirror-polished to have a surface roughness Ra of 0.05 μm. Ni target of the present invention in which the non-erosion portion on the sputter surface side is mirror-polished to have a surface roughness Ra of 0.05 μm, and the surface roughness Ra of the aluminum alloy backing plate is maintained at 0.5 μm while the sputter surface side is cut. 2. Surface roughness Ra of all of the pure Ni disc including the non-erosion portion on the sputter surface side and the sputter surface side of the aluminum alloy disc Ra: 0.0
The Ni target 3 of the present invention, which was mirror-polished to 5 μm, pure Ni
The entire surface of the sputter surface including the non-erosion part of the disk is mirror-polished to have a surface roughness Ra of 0.05 μm, and the surface roughness Ra of the aluminum alloy backing plate is kept at 0.5 μm while the sputter surface side is cut. The present invention Ni target 4 and the surface roughness Ra of the entire sputter surface side including the non-erosion portion of the pure Ni disc and the sputter surface side of the aluminum alloy disc as cut Ra: 0.5 μ
A conventional Ti target held at m was prepared. These Ni targets 1 to 4 of the present invention and conventional Ni targets
The target was placed in a DC magnetron sputtering apparatus, and sputtering was repeatedly performed under the same conditions as in Example 1, and the number of Si wafers until the number of particles in the Ni film exceeded 100 particles / wafer was measured. The measurement results are shown in Table 2.

[0016]

[Table 2]

Example 3 As a target, a pure Co disk having a purity of 99.999% and a size of diameter: 250 mm × thickness: 10 mm was prepared.
This pure Co disc is diffusion-bonded to an aluminum alloy disc to prepare a target substrate composed of a pure Ni disc and an aluminum alloy backing plate, and the target Co substrate has a non-erosion side of the pure Co disc on the sputtering surface side. Surface roughness Ra of the Co target 1 of the present invention, in which the sputtering surface side of the aluminum alloy backing plate and the sputter surface side of the aluminum alloy are both mirror-polished to a surface roughness Ra of 0.05 μm, and the sputter surface side non-erosion portion of the pure Co disk. Surface roughness Ra: 0.5 μm after being mirror-polished to 05 μm and cutting the sputter surface side of the aluminum alloy backing plate
Co target 2 of the present invention held on the whole surface, the entire sputtering surface side including the non-erosion portion of the pure Co disk, and the sputtering surface side of the aluminum alloy backing plate are mirror-polished to have a surface roughness Ra of 0.05 μm. The surface roughness Ra of the target 3 and the pure Co disk, including the non-erosion portion, is mirror-polished to a surface roughness Ra of 0.05 μm, and the aluminum alloy disk has a surface roughness Ra as cut. Inventive Co held at 0.5 μm
The target 4 and a conventional Co target in which the entire surface of the pure Co disk on the sputter surface and the surface of the aluminum alloy disk on the sputter surface were cut to a surface roughness Ra of 0.5 μm without being mirror-polished. Each of the Co targets 1 to 4 of the present invention and the conventional Co target produced as described above were loaded into a DC magnetron sputtering apparatus, and sputtering was repeated under the same conditions as in Example 1 to obtain Co.
The number of Si wafers until the number of particles in the film exceeds 100 / wafer was measured, and the measurement results are shown in Table 3.

[0018]

[Table 3]

Example 4 As a target, a pure Cu disk having a diameter of 250 mm and a thickness of 10 mm and a purity of 99.999% was prepared.
This pure Cu disc is diffusion-bonded to an aluminum alloy disc to prepare a target substrate composed of a pure Cu disc and an aluminum alloy backing plate, and a non-erosion portion of the pure Cu disc on the sputtering surface side of the target substrate and The Cu target 1 of the present invention in which the sputter surface side of the aluminum alloy backing plate is mirror-polished to a surface roughness Ra of 0.05 μm, and the non-erosion portion of the pure Cu disk on the sputter surface side has a mirror surface of Ra: 0.04 μm. The Cu target 2 of the present invention, which has been polished and the surface roughness Ra of the backing plate made of an aluminum alloy is kept at 0.5 μm as it is cut, the entire sputtering surface side including the non-erosion portion of the pure Cu disk and aluminum. Surface roughness Ra on the sputter surface side of the alloy backing plate:
Cu target 3 of the present invention mirror-polished to 0.04 μm,
The surface roughness Ra of the pure Cu disk including the non-erosion portion is polished to a surface roughness Ra of 0.04 μm, and the surface roughness Ra of the aluminum alloy backing plate is 0.5 μm. The Cu target 4 of the present invention held on the above, and the entire surface of the sputter surface including the non-erosion portion of the pure Cu disc and the surface of the aluminum alloy backing plate on which the sputter surface is cut without mirror polishing Ra: A conventional Cu target held at 0.5 μm was produced, and the Cu of the present invention was prepared.
A target 1 to 4 and a conventional Cu target were placed in a DC magnetron sputtering apparatus, and sputtering was repeated under the same conditions as in Example 1 to obtain 100 Si wafers per wafer in the Cu film. The number of sheets was measured, and the measurement results are shown in Table 4.

[0020]

[Table 4]

[0021]

From the results shown in Tables 1 to 4, the target for magnetron sputtering in which the surface roughness Ra of at least the non-erosion portion on the sputtering surface side of the target is mirror-polished to 0.01 to 0.09 μm is obtained. , 0.2μ compared to conventional target which is not mirror polished
It can be seen that the number of Si wafers is large until the number of particles of m or more exceeds 100 / wafer, and particles are less likely to be generated. Therefore, the target of the present invention can suppress the occurrence of large numbers of coarse particles during film formation for a long period even in high-power sputtering.
The magnetron sputtering device can be satisfactorily dealt with in upsizing and high performance and has a long service life.

Claims (3)

[Claims] 1. A surface roughness Ra of 0.01 to 0.09 μm (provided that R
A is a target for magnetron sputtering, which is mirror-polished to a centerline average roughness (the same applies hereinafter). 2. The surface roughness Ra of the entire target surface including the non-erosion portion of the target is Ra: 0.01 to 0.09 μm.
A target for magnetron sputtering, which is mirror-polished to m. 3. The surface roughness R on the sputtering surface side of the backing plate supporting the target according to claim 1 or 2.
a: A target for magnetron sputtering, which is mirror-polished to 0.01 to 0.09 μm.