JPH027870Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention]
This invention relates to a target for a magnetron sputtering device used for forming a light-shielding film on a mask.

[Prior art]

In recent years, this type of device has created a leakage magnetic field in which lines of magnetic force trace an arc outside the target surface, and an electric field perpendicular to this magnetic field.This orthogonal electromagnetic field space allows plasma generated in a vacuum to be directed to the target surface. The demand for high-speed magnetron sputtering devices that confine the magnetic field within the area surrounded by the above-mentioned arcuate lines of magnetic force is rapidly increasing.

While classical magnetron sputtering devices used a uniform magnetic field, this system purposely uses a non-uniform magnetic field to more efficiently focus high-density plasma. can be,
This resulted in a dramatic improvement in productivity.

However, in such a magnetron sputtering device, the plasma region is not formed uniformly over the entire target surface due to its principle, and therefore the target has a sputtering area corresponding to the plasma region. This results in the formation of an erosion region where sputtering occurs and a non-erosion region where sputtering hardly occurs. As sputtering continues in such a state, sputtered atoms from the erosion region are deposited on the surface of the non-erosion region.
Furthermore, the flakes may peel off and fall into the erosion area, making sputtering unstable.In particular, the scattered flakes may adhere to the surface of the substrate to be processed, such as a glass substrate for a photo mask, inhibiting the adhesion of sputter atoms. This may cause pinholes to form in the sputtered film.

[Purpose and structure of the invention]

The present invention was developed in view of these circumstances, and its purpose is to prevent defects from occurring in the spatter film on the substrate to be processed due to the peeling and scattering of the target material layer deposited in the non-erosion area. It is an object of the present invention to provide a target for a magnetron sputtering device that can prevent such problems.

In order to achieve this purpose, the present invention
The surface of the non-erosion area of the target is roughened. Hereinafter, the present invention will be explained in detail using the illustrated embodiments.

〔Example〕

FIG. 1 is a sectional view of a main part of a magnetron sputtering device showing an embodiment of the present invention. This is an example used in a so-called planar type DC magnetron sputtering device, and a target 2 made of, for example, chromium is placed in the center of a vacuum chamber 1 into which an inert gas, argon gas, is introduced. In the illustrated example, the target 2 is placed on a base material 3 made of copper, but this base material may be omitted if the target has a sufficient area. On the back side of this target 2, a columnar magnet 4a and an annular magnet 4b surrounding it are attached to the target 2.
The sides are arranged as the S pole and the N pole. Also,
A frame-shaped shield member 5 is arranged around the surface side of the target 2. The shield member 5 is arranged so that its end portion covers the outer edge of the target 2, and prevents spatter atoms from adhering to a substrate other than a glass substrate (not shown) as a substrate to be processed, which is arranged opposite to the target surface. In this example, it also serves as an electrode, and a DC voltage is applied using the shield member 5 as an anode and the target 2 as a cathode.

The target 2 has a rectangular flat plate shape as shown in FIG. 2, and on the outside of its surface, lines of magnetic force 11 are formed in an arc shape, coming out from the annular north pole arranged on the back surface and entering the central south pole. There is. As a result, an orthogonal electromagnetic field space is created in the space between the pair of magnetic poles, where the lines of magnetic force and the lines of electric force due to the DC voltage are orthogonal to each other, and the plasma generated in a vacuum is created by the arcuate magnetic lines of force in a donut-shaped region 12. to be confined in The electron is
As shown by the trajectory 13, this plasma region 1
The cycloidal movement within the argon ions increases the generation of argon ions, which increases the density of the plasma and increases the sputtering efficiency.

Here, as shown in FIG. 3, the target 2 is formed with an erosion region 21 as a sputter region corresponding to the plasma region 12, and non-erosion regions 22 and 23 at the center and outer edges. As mentioned earlier, the target material layer deposited in the non-erosion region conventionally caused defects in the sputtered film on the substrate to be processed. This problem is solved by forming the target surfaces of regions 22 and 23 into a rough shape as shown in FIG. In other words, in the case of chromium, the layer deposited in the non-erosion region peels off with a thickness of about several tens of μm on a conventional smooth surface, but for example, it peels off with a thickness of about several tens of μm, which is one order of magnitude larger than the thickness of the deposited layer 2a. By providing this unevenness on the surface of the non-erosion area, we were able to reduce the frequency of maintenance work to scrape off the deposited layer to about 1/3 to 1/5 of the conventional level. This is because it becomes difficult for spatter atoms to adhere due to changes in the surface condition, and in particular, as is clear from FIG. This is thought to be due to the fact that the adhesion strength of the deposited layer increased due to the increase, and once the adhesion was applied, it became difficult to peel off easily.

Note that sandblasting and chemical etching are generally used as processing techniques to roughen the metal surface, but the chromium target in this example is made of a hard material and is difficult to process by sandblasting using ordinary glass beads. Therefore, a chemical etching method using an etching solution containing hydrochloric acid as the main component was used. That is, the target surface of the erosion region 21 was covered with a protective film, and only the surfaces of the non-erosion regions 22 and 23 were brought into contact with the etching solution, and etching was carried out for several hours. Of course, this etching time is set to an appropriate value in relation to the concentration of the etching solution. Although it takes some time, other etching solutions such as cerium ammonium nitrate, perchloric acid, and water, which are generally used when etching a chromium film sputtered on a glass substrate to form a mask pattern, can be used. Even when a liquid is used, the surface can be roughened by a similar method. Of course, a sandblasting method is also possible if a harder material is used instead of ordinary glass beads.

The above explanation was given using the chrome target as an example. This is because in the case of chromium, the target material layer deposited in the non-erosion area is much more likely to peel off than with aluminum, which is more likely to cause problems, but of course, this also applies when other target materials are used. In this case, for soft targets such as aluminum, a common sandblasting method using glass beads can be used as a roughening method.

Furthermore, in the above-described embodiment, the surface of the entire non-erosion area at the center and outer edge is roughened, but when using the shield member 5 as shown in the figure, most of the non-erosion area at the outer edge is roughened. Therefore, it is possible to obtain substantially the same effect even if this portion is omitted from being roughened and only the central non-erosion region 22 is roughened.

Note that the reason why the surface of the erosion region 21 was not roughened is that if there are irregularities in this part, the electric field will concentrate on the protrusion, causing abnormal discharge and adversely affecting the formation of the spatter film, so this should be avoided. It's for a reason.

Furthermore, in order to achieve the same purpose as the present invention, it is conceivable to provide an insulating plate that covers the non-erosion area and is detachable (see, for example, Japanese Patent Publication No. 14107/1983). The target is the material itself that will form the desired sputtered film, and placing foreign matter there should be avoided from the perspective of contamination with impurities. Also,
This method does not prevent the deposition or peeling of the target material layer itself, but instead of scraping off the target material layer deposited in the non-erosion area, the insulating plate on which the target material layer is deposited is frequently replaced. The need arises. On the other hand, the present invention suppresses adhesion of the target material layer or its peeling itself, so it has the advantage that such maintenance work can be fundamentally reduced and the problem of foreign matter as described above does not occur.

The above explanation has been given using a rectangular plate-shaped target used in a planar type magnetron sputtering device as an example, but of course, a round plate-shaped target may also be used, and it is not limited to a planar type. A plasma region is formed in
The present invention can generally be applied to a target used in a magnetron sputtering device in which an eroded region and a non-eroded region are generated in the target to obtain similar effects.

[Effect of idea]

As explained above, according to the present invention, by roughening the non-erosion region of the target, it is possible to prevent defects in the sputtered film caused by peeling and scattering of the target material layer deposited in the non-erosion region. can photo mask,
The quality of semiconductor devices and the like can be improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a main part of a magnetron sputtering device showing an embodiment of the present invention, Fig. 2 is a diagram for explaining the principle of sputtering, Fig. 3 is a plan view showing a target, and Fig. 4 is It is a sectional view of the main part. 2... Target, 2a... Target material layer, 21... Erosion region, 22, 23...
Non-erosion area.

Claims (1)

[Scope of utility model registration request] A magnetic pole placed on the back surface of the target forms a leakage magnetic field with arcuate lines of magnetic force on the outside of the target surface, and an electric field perpendicular to the magnetic field, directing the generated plasma to the area on the target surface surrounded by the arcuate lines of magnetic force. A target used in a magnetron sputtering apparatus that performs sputtering in a confined manner, characterized in that at least a part of the surface of the non-erosion area, excluding the erosion area corresponding to the plasma area, is formed into a rough surface. Target.