JPH04337068A - Magnetron reactive sputtering apparatus - Google Patents

Abstract

PURPOSE:To improve the rate of sputtering by providing a cooling controlling layer between a backing plate and a material target. CONSTITUTION:As for sputtering, high voltage is impressed on a platen 2 and a magnet electrode 4 to generate glow discharge and to form a film on the surface of a wafer 3. A backing plate 6 is cooled by cooling water via a magnet electrode 4, but, a cooling controlling board 7 of a material having 0.5 to 1mm thickness and thermal conductivity lower than that of copper such as SuS is interposed between the backing plate 6 and a target 8, the temp. of the target 8 is held to a one higher than heretofore, by which reactive sputtering with a higher rate is permitted.

Description

[Detailed description of the invention]

[Object of the invention]

FIELD OF THE INVENTION This invention relates to improvements in reactive sputtering equipment.

0002

2. Description of the Related Art Conventionally, sputtering gas and reaction gas are introduced as process gases into a vacuum chamber, high pressure is applied to two electrodes to cause glow discharge, and atoms of a material target are ejected by sputtering gas ions. 2. Description of the Related Art A sputtering apparatus is known that causes a reaction between target material atoms and reactive gas ions to generate a reaction product film on a wafer surface facing the target.

[0003] Among such sputtering apparatuses, there is one called a magnetron sputtering apparatus, in which a magnet is attached to the electrode on which the material target is placed, and the magnetic field of this magnet generates high-density plasma near the surface of the target. This plasma is used to increase the sputtering speed of the target and perform high-rate sputtering, and in recent years it has been widely used as a very useful technology.

By the way, FIG. 4 shows the structure of a target electrode part of a conventional magnetron reactive sputtering apparatus, in which 40 is a magnetron electrode, 41 is a backing plate, 42 is a material target, and 43 is a structure in which the target 42 is attached to the backing plate 41. The fixing screw 44 is also a target holder.

As shown in this figure, the magnetron sputtering apparatus is equipped with a backing plate 41 as a holding plate for disposing a target on a magnet electrode 40. As shown in FIG. In magnetron sputtering equipment, since a large current density discharge is used, it is necessary to prevent the temperature of the target itself from rising excessively. However, since it is not possible to directly immerse the target in cooling water, the target 42 is placed on the backing plate 41. The target 42 is cooled indirectly by loading the backing plate 41 and cooling it sufficiently. Note that the main purpose of this cooling water is to cool the magnetron electrode 40.

However, the current situation is that the sputtering rate of this conventional magnetron sputtering apparatus is limited to a certain level.

That is, first, in reactive sputtering, a sputtering gas (usually Ar) and a reactive gas (N2, O2,
CH4, etc.) are simultaneously incident on the target surface. Normally, the reaction rate between the reactive gas and the target material is faster than the rate at which the target material is sputtered, so the target surface is covered with reactants at the time of sputtering, and therefore the film deposited on the substrate is Becomes a reactant. As the sputtering speed is gradually increased, there is a point where it becomes faster than the reaction rate, and after this point, the film deposited on the substrate becomes the same as the target material, and the film formed by the reactants There are limits to speed.

[0008] In order to increase the rate of film formation of the reactant, it is necessary to accelerate the reaction between the reaction gas and the target material to increase the reaction rate, and one way to do this is to increase the temperature of the target.

[0009] As a means of increasing the temperature of this target, it is conceivable to suppress the degree of cooling thereof.

[0010] Possible cooling suppression means include changing the material of the backing plate and changing the cooling water system.

[0011] However, copper (Cu) is mainly used for this backing plate due to its thermal conductivity, reactivity with the target, corrosion caused by cooling water, etc., and the material is almost limited. It is difficult to suppress the degree of cooling of the target by changing the material of this backing plate.

[0012] In addition, cooling water is mostly used not only for cooling the target but also for cooling the magnetron coil in magnetron sputtering.
It is difficult to raise or stop the cooling water temperature.

For these reasons, in reactive sputtering, the sputtering rate of the target reactant is fixed to a certain extent.

[0014]

SUMMARY OF THE INVENTION As described above, in the conventional magnetron reactive sputtering apparatus, the sputtering rate has reached a ceiling.

The present invention has been made in view of this problem, and its purpose is to improve the backing plate without reducing its thermal conductivity, reactivity with targets, and corrosion resistance against cooling water. Another object of the present invention is to provide a magnetron reactive sputtering device that can improve the sputtering rate without reducing the cooling ability of the magnetron coil.

[Configuration of the invention]

[Means to solve the problem]

The magnetron reactive sputtering apparatus of the present invention includes a layer that suppresses cooling of the material target by the backing plate between the backing plate provided on the magnet electrode and the material target provided on the backing plate. It is characterized by:

[0017] This cooling suppression layer may be formed, for example, by interposing a material with lower heat conductivity than the backing plate between the backing plate and the target, or by providing a hollow groove or a cooling layer in at least one of the backing plate and the material target. This can be achieved by, for example, forming a solid groove in which a suppressor is embedded.

[0018]

[Operation] According to the present invention, temperature control of the target is achieved by disposing a cooling suppression layer between the backing plate and the target. The sputtering rate can be improved without reducing the corrosion resistance and without reducing the cooling ability of the magnetron coil.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows the internal structure of a sputtering apparatus according to a first embodiment of the present invention.

In this figure, 1 is a chamber, and a platen 2 is disposed in the upper part of the chamber 1, and a wafer 3, which is a substrate to be processed, is held on the back surface of the platen 2.

A magnet electrode 4 is arranged in the lower part of the chamber 1 so as to face the platen 2. A cooling water passage is formed in the magnet electrode 4, and a cooling water passage is formed in the magnet electrode 4 through a hollow shaft 5 connected to the lower part thereof. Cooling water is supplied to the cooling water passage. A backing plate 6 made of copper (Cu), for example, is placed on the surface of the magnet electrode 4, and the backing plate 6 has a thickness of 0.5 to 1.0 m.
An annular cooling suppression plate 7 made of a material having a thermal conductivity lower than that of copper, such as stainless steel, is placed at m, and a titanium (Ti) target 8 is placed on the surface of this cooling suppression plate 7. The cooling suppression plate 7 and the target 8 are fixed to the backing plate 6 by a set screw 9 screwed into the center thereof and a target holder 10 which presses the peripheral side.

In the above configuration, first, sputtering is performed by introducing argon gas (Ar), which is a sputtering gas, and nitrogen gas (N2), which is a reaction gas, into the chamber 1 as a process gas, and also using two electrodes (platen 2). A high voltage is applied to the magnet electrode 4) to cause a glow discharge, and the atoms of the target 8 are struck out by argon ions (Ar+). Here, if a titanium (Ti)-based target is used as the target 8, its atoms will react with nitrogen ions (N-), resulting in titanium nitride (TiN).
) film will be formed on the surface of the wafer 3. Further, the magnetic field of the magnet electrode 4 creates high-density plasma near the surface of the target 8, and the sputtering speed of the target 8 is increased by this plasma.

The backing plate 6 is cooled by cooling water via the magnet electrode 4, but between the backing plate 6 and the target 8 there is a cooling suppressing plate having a lower thermal conductivity than the backing plate 6. Since the target 7 is interposed, the target 8 is maintained at a higher temperature than before, and a higher rate of reactive sputtering becomes possible.

Incidentally, as mentioned above, as a result of forming a TiN film using Ar and N2 as process gases,
While the conventional rate was 12 to 14 angstroms/sec, according to the present invention, the rate was improved to 24 to 26 angstroms/sec.

In this example, a thin stainless steel plate was used as an example of the cooling suppressor, but similar effects can be expected with high melting point metals or their nitrides, silicides, carbides, and borides. can.

FIG. 2 shows the structure of a target electrode portion of a sputtering apparatus according to a second embodiment of the present invention.

In the device shown in this figure, a cooling suppression groove 12 is formed on the back surface of the target 8', and the space of this cooling suppression groove 12 reduces the contact area between the target 8' and the backing plate 6, thereby reducing heat. It is characterized by suppressing conduction. Here, the cooling suppression groove 12 is formed as an annular groove having a depth of 1 to 2 mm and a width of 5 to 6 mm, coaxial with the target 8', and has three grooves with different diameters spaced apart at an interval of 5 to 6 mm. It is set aside.

Here, the space of the groove 12 was used as it is for suppressing heat conduction, but in this groove 12 there is a high melting point metal,
Alternatively, similar effects can be obtained by embedding nitrides, silicides, carbides, or borides thereof.

FIG. 3 shows the structure of a target electrode portion of a sputtering apparatus according to a second embodiment of the present invention.

What is shown in this figure is that an annular groove 13 is formed on the surface of the backing plate 6', which is coaxial with the target 8, has the same area as the target 8, and has a depth of 1 to 2 mm. A cooling suppressing object 14 as described above is embedded in the cooling suppressing object 13, and the low thermal conductivity of this cooling suppressing object 14 is utilized.

Even in the case of this embodiment, the space may be utilized without embedding the cooling suppressor as in the structure of the second embodiment.

Furthermore, in the second and third embodiments, the cooling suppression layer was provided on the back surface of the target 8' and a part of the surface of the backing plate 6', but it may be formed on the entire surface.

Further, in all of the above embodiments, the cooling suppression layer has a thickness of 0.5 to 2.0 mm, but even if this thickness is on the order of the surface treatment, similar effects can be expected.

Therefore, the present invention is not limited to the above-mentioned embodiments, and the cooling suppressing layer can be provided in various structures.

[0035]

As explained above, according to the present invention, temperature control of the target is achieved by disposing a cooling suppression layer between the backing plate and the target. The sputtering rate can be improved without reducing the reactivity of the magnetron, the corrosion resistance to cooling water, and the cooling ability of the magnetron coil.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a magnetron reactive sputtering apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of a target electrode portion of a magnetron reactive sputtering apparatus according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing the structure of a target electrode portion of a magnetron reactive sputtering apparatus according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the structure of a target electrode portion of a conventional magnetron reactive sputtering device.

[Explanation of symbols]

1 Sputter chamber 2 Platen 3 Wafer 4 Magnetron electrode 5 Hollow shaft 6 Backing plate 7 Cooling suppression plate 8 Material target

Claims (3)

[Claims] 1. A layer for suppressing cooling of the material target by the backing plate is provided between a backing plate provided on a magnet electrode and a material target provided on the backing plate. Magnetron reactive sputtering equipment. 2. The magnetron reactive sputtering apparatus according to claim 1, wherein the cooling suppression layer is constituted by a hollow groove formed in at least one of the backing plate and the material target. 3. The magnetron reactive sputtering apparatus according to claim 1, wherein the cooling suppressing layer is constituted by a solid groove formed in at least one of the backing plate and the material target and having a cooling suppressing material embedded therein. .