JP4057287B2 - Manufacturing method of erosion profile target - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a film uniformity (film thickness uniformity) that is good throughout the sputtering life of the target, produces less particles, does not deform the target during sputtering, and has a long target life . It relates to the production method.
[0002]
[Prior art]
Thin film forming methods by sputtering are widely used in the production of various electronic and electrical components.
In the sputtering method, a substrate serving as an anode and a target serving as a cathode are opposed to each other, and an electric field is generated by applying a high voltage between these substrate and target in an inert gas atmosphere. Electrons and inert gas collide to form a plasma. The cations in the plasma collide with the target surface and strike target atoms, and the ejected atoms adhere to the opposing substrate surface to form a film. This is based on the principle that
[0003]
Currently, most of sputtering uses a so-called magnetron sputtering method. Magnetron sputtering is a method in which a magnet is set on the back side of a target and a magnetic field is generated in the direction perpendicular to the electric field on the target surface to perform sputtering. In such an orthogonal electromagnetic field space, plasma stabilization and densification are achieved. It is possible to increase the sputtering rate.
[0004]
In general, magnetron sputtering captures electrons in a magnetic field and efficiently ionizes the sputtering gas, but the structure and type of the magnet, as well as the sputtering conditions, the target material (especially non-magnetic or magnetic material), and the type of sputtering equipment The target erosion (erosion) is different during sputtering, and uniform erosion is not achieved. This applies not only to the magnetron sputtering method but also to other sputtering methods.
The target reaches the end of its life when the deepest erosion is reached and is replaced with a new target. In general, the target is formed in a flat plate shape, but such a target has a disadvantage that its life is relatively short.
[0005]
In addition, when the target is locally deeply eroded, sputtering does not occur uniformly, the film uniformity (thickness uniformity) deteriorates, and there is a problem that particles increase at protrusions or corners. To come.
Moreover, such a change in the target shape during the sputtering operation causes residual distortion and deformation in the target itself, which causes cracks and cracks in the target itself, or peels off from the backing plate, resulting in insufficient cooling and abnormalities. Problems such as further increase in discharge and particles occur.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems or disadvantages, and improves the film uniformity (film thickness uniformity) throughout the sputtering life of the target, and the generation of particles is small. An object of the present invention is to provide a method for producing an erosion profile target with no deformation of the target and with a long target life.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventor pays attention to the shape of the target for sputtering, sets the target shape to which erosion is expected, and performs sputtering using the target, so that the uniformity of the film (thickness of the film thickness) is increased. The present inventors have found that (uniformity) is good, the generation of particles is small, the target is not deformed during sputtering, and the life of the target can be extended. Note that the “erosion profile target” used in this specification means a target having a shape that assumes erosion.
[0008]
The present invention is based on the above findings.
1. Plate-shaped based by sputtering targets erosion shape and depth, the amount corresponding to the erosion shape and depth, a target manufacturing method of increasing the thickness of the target, the thickness d ₀ of the flat target when the maximum depth of erosion by sputtering and dmax, as the ratio d ₀ of a value obtained by multiplying a proportional constant dmax is 0.1 to 0.5, the same proportion to the target thickness increase An erosion profile target manufacturing method for multiplying a constant to increase a target thickness is provided.
[0009]
(Delete)
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a method for manufacturing an erosion profile target, and the manufactured erosion profile target is within 1.5 times the thickness of the other parallel portion of the target area deeply eroded by sputtering. It has a thick structure . As a result, the target thickness reduction amount of the portion that is selectively deeply eroded is made substantially the same as other portions.
Such an erosion profile target having a non-uniform thickness can extend the life of the target and can improve the film uniformity (film thickness uniformity) through the sputtering life.
Further, such an erosion profile target eliminates the formation of the extreme deepest part compared to the conventional flat target, and becomes an averaged erosion form, so that the generation of particles is small, and the deformation of the target during sputtering is further reduced. It has the feature of not. The target area to be eroded is thickened within 1.5 times the thickness of the other parallel parts, but if the thickness exceeds this, the film uniformity tends to deteriorate at the initial stage of sputtering. The maximum thickness is preferably 1.5 times.
[0011]
It is desirable that the erosion profile target manufactured by the manufacturing method of the present invention has a gentle undulation with the target surface continuously changing. As a result, the occurrence of extreme protrusions and corners during the sputtering operation is reduced, the occurrence of abnormal discharge and particles is further reduced, and good sputtering can be maintained.
When the erosion profile target manufactured by the manufacturing method of the present invention is a disk-shaped target, it has two ring-shaped convex portions concentrically, and the inner ring-shaped convex portion is thicker than the outer ring-shaped convex portion. It can be made thicker than the thickness.
In general, in magnetron sputtering that is often used, the erosion part is often formed in two rings concentrically as described above, and the inner ring-shaped convex part is more particularly than the outer ring-shaped convex part. By making it thick, stable sputtering can be performed, and the uniformity of the film can be made more uniform.
[0012]
In addition, the erosion profile target manufactured by the manufacturing method of the present invention has a surface roughness Ra ≦ 1.0 μm in the target region deeply eroded by sputtering and the vicinity thereof, and the surface roughness of other portions where erosion is not severe. The thickness is preferably 10 μm ≦ Ra ≦ 20 μm.
10 μm ≦ Ra ≦ 20 μm means a surface roughened portion. The erosion part in the target is mainly only at a specific portion, and erosion is rare in other parts. In such a case, the redeposition film may adhere to and accumulate on such a non-erosion part, and it may peel off and float, which may cause generation of particles. Therefore, it can be said that it is more desirable for the non-erosion part to prevent the attached redepo film from peeling off.
From the above, the surface roughened portion of 10 μm ≦ Ra ≦ 20 μm is effective in preventing such peeling of the redeposite film.
[0013]
Moreover, the erosion profile target manufactured by the manufacturing method of this invention inclines the side surface of this target, and makes the inclination | tilt angle 60 degrees or more with respect to a horizontal surface. By adjusting this angle, it is possible to reduce the temperature change due to sputtering at the target corner and prevent the redeposition film from peeling off.
Further, it is desirable that the side surface of the sputtering target has two inclinations, the outer inclination is 60 ° or more with respect to the horizontal plane, and the inner inclination is 20 ° to 60 ° with respect to the horizontal plane. Thereby, the formation of a redepo film having a weak adhesion can be effectively prevented. The contrivance of the target side surface is particularly effective for an erosion profile target having a long lifetime.
[0014]
In addition, the erosion profile target manufactured by the manufacturing method of the present invention preferably has a roughened surface with a surface roughness of 10 μm ≦ Ra ≦ 20 μm on the side surface of the target. As a result, it is possible to prevent the redeposition film from adhering and depositing on the side surface of the target, peeling off and floating, and generating particles. In order to prevent this peeling, it is preferable to have a surface roughened portion of 10 μm ≦ Ra ≦ 20 μm.
The sputtering target of the present invention can be applied to aluminum, copper, tantalum, titanium, nickel, cobalt, ruthenium, tungsten, rhodium, or alloys thereof that can be machined such as a lathe. It is also effective for a magnetic material target for forming a thin film by using magnetron sputtering.
[0015]
When the assembly structure of the erosion profile target and the backing plate according to the present invention is manufactured, the side surface of the sputtering target can be embedded in the backing plate. An embedding depth corresponding to the thickness increase is appropriate.
Regarding the magnetic material target, it is necessary to increase the sputtering efficiency by making the target as thin as possible because of its characteristics, but there is a tendency that the strength is weakened accordingly. Therefore, the structure in which the target is embedded in the backing plate can prevent the target from being deformed or cracked, and can reinforce the weak point.
Further, the backing plate has a structure in which the cooling medium is circulated, but the cooling efficiency can be remarkably increased by making the target embedded in the backing plate in this way. Therefore, higher power sputtering is possible, and this structure can be adopted depending on the purpose.
[0016]
In manufacturing the erosion profile target of the present invention, a flat target is sputtered in advance, and the erosion shape and depth at that time are examined, and based on this, the thickness of the target can be adjusted.
In this case, when the maximum depth of erosion by sputtering of a flat target having a thickness of d ₀ is dmax, the proportional constant for the increase in thickness is set so that 0.1 ≦ dmax / d ₀ ≦ 0.5. By multiplying, the target thickness can be increased accordingly.
The condition of 0.1 ≦ dmax / d ₀ ≦ 0.5 is the upper limit value and the lower limit value when the target is thickened, and if it is less than 0.1, there is no effect, and if it exceeds 0.5, in the initial stage of sputtering. Rather, since the uniformity of the film may be deteriorated, the above range is desirable.
Accordingly, even if there is a difference in erosion that varies depending on the type of target material, an erosion profile target can be easily manufactured according to the specific target erosion.
[0017]
Next, the present invention will be described based on examples. In addition, the following examples are for making the invention easily understood, and the present invention is not limited to these examples. That is, other examples or modifications based on the technical idea of the present invention are naturally included in the present invention.
[0018]
Example 1
As shown in FIG. 1, a flat plate Ti target 1 having a diameter of 300 mm and a thickness of 10.0 mm (d ₀ ) was first magnetron sputtered. Sputtering was performed at a sputtering power of 15 kW up to 1500 kWh.
The erosion profile 2 of the target after sputtering shown in FIG. 1A was measured at 61 points on the central gland with a three-dimensional measuring device at equal intervals.
The maximum erosion depth (dmax) was 4.50 mm. Next, as shown in (b) FIG. 1, the unevenness of the erosion profile 2 by inversion, so that the value of this dmax / _{d 0} is 0.35, over proportionality constant 0.78 surface The shape was adjusted. The position data of 31 points for a semicircle was input to an NC lathe to produce a Ti target with a maximum thickness of 13.5 mm. (C) of FIG. 1 shows the erosion profile target 3 after adjusting the surface shape. Reference numeral 4 denotes a backing plate.
This erosion profile target 3 was able to be sputtered with the same sputtering power for about 1.5 times longer than the flat target.
[0019]
(Example 2)
As shown in FIG. 2, the target 5 according to the present invention is embedded in the backing plate 6 by 3.5 mm, the first slope 7 on the side surface is 60 °, the second slope 8 is 30 °, and the vicinity of this slope portion. When the surface roughening treatment of 12 μmRa was performed, the number of generated particles could be suppressed to be smaller than that of the flat target.
[0020]
(Other examples of target shapes)
FIG. 3 shows another target example manufactured by the manufacturing method of the present invention. FIG. 3A shows an example in which the outer ring-shaped convex portion is thicker than the inner ring-shaped portion. FIG. 3B shows an example in which the outer ring-shaped convex portion is thicker than the inner ring-shaped convex portion, and the central portion also has a convex portion. FIG. 3C shows an example in which there are three ring-shaped convex portions concentrically. FIG. 3D shows an example in which there is a convex portion at the center, and this convex portion is thicker than other ring-shaped convex portions.
The target erosion is affected by the magnet structure of the sputtering apparatus, but as shown in the above example, the shape of the target can be appropriately designed according to the specific erosion profile.
[0021]
【The invention's effect】
The erosion profile target manufactured by the manufacturing method of the present invention can extend the life of the target, improve the film uniformity (film thickness uniformity) through the sputtering life, It has the excellent effect that there is little generation | occurrence | production and there is little deformation | transformation of the target during sputtering.
Furthermore, even if there is a difference in erosion that varies depending on the type of target material, an erosion profile target can be easily manufactured according to the specific target erosion.
[Brief description of the drawings]
FIG. 1A is an explanatory diagram showing an erosion profile of a flat target, FIG. 1B is an explanatory diagram showing the erosion profile with the irregularities inverted, and FIG. 1C is an explanatory diagram showing the erosion profile target after the surface shape is adjusted. FIG.
FIG. 2 is an explanatory diagram of a sputtering target having two inclined side surfaces.
FIG. 3 is an explanatory cross-sectional view showing other examples (A to D) of the target shape.
[Explanation of symbols]
1: flat target 2: erosion profile 3: erosion profile target after adjusting the surface shape 4: backing plate 5: target 6 of the present invention: backing plate 7 embedded with the target of the present invention 7: first inclined surface 8 : Second side slope

Claims (1)

Plate-shaped based by sputtering targets erosion shape and depth, the amount corresponding to the erosion shape and depth, a target manufacturing method of increasing the thickness of the target, the thickness d ₀ of the flat target when the maximum depth of erosion by sputtering and dmax, as the ratio d ₀ of a value obtained by multiplying a proportional constant dmax is 0.1 to 0.5, the same proportion to the target thickness increase A method of manufacturing an erosion profile target by multiplying a constant to increase the thickness of the target.

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