JPS58199862A - Magnetron type sputtering device - Google Patents

Abstract

PURPOSE:To improve the uniformity of a film by a wide sputtering area, by providing means such as electromagnets in a plasma focusing magnet, and changing the field intensity on the surface of a target according to the sputtering rate of the target. CONSTITUTION:Electromagnets 16, 17 or high magnetically permeable materials 18, 19 are provided in a plasma focusing magnet 4 in a magnetron type sputtering device. If the target is in the state in which the central part thereof is sputtered more as compared to the peripheral part, electric current is flowed to the electromagnet 16 to apply the magnetic flux in the direction opposite to the magnetic flux generated by the magnet 4 passing through the central part of the target 3. Then, the magnetic resistance in the central part of the target 3 is apparently decreased and the surface magnetic field acts uniformly over the entire part of the surface of the target 3. The magnetic field intensity on the target 3 is changed according to the sputtering rate and the target 3 is sputtered roughly uniformly by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a magnetron type sputtering apparatus, and particularly to a case where a magnetic material is used as a target.

(Background Art) Sputtering is a technique in which an object is bombarded with ions, and the atoms and molecules released from the surface of the object are deposited on the surface of a target substrate to form a thin film. This technology has a wide range of applications, and various studies have been conducted since then. Among these, magnetron sputtering is also called high-speed low-temperature sputtering, and has disadvantages of conventional bipolar sputtering, etc. (1) The deposition rate is extremely slow at less than 0.11μm1m1n, and (2) the electrons collide with the substrate, causing damage to the substrate. The temperature rises rapidly (
This technique was developed by focusing on the problem of argon and other rare gas ions. The point is to make it. The basic configuration of a conventional magnetron type sputtering apparatus is shown in FIG. 1 is a chamber that keeps the entire device in a vacuum. 2 is a substrate, on the surface of which sputtered atoms or molecules adhere to form a thin film. 3 is a target, which is a material to be sputtered. Various materials may be selected depending on the desired thin film. 4 is a plasma focusing magnet, which applies a magnetic field perpendicular to the electric field acting between the substrate 2 and the target 3 on the surface of the target 30. Due to the action of this magnetic field, a plasma containing, for example, archon gas is
As shown in Figures 5 and 6, a convex high-density plasma region is formed on the target surface. This situation is shown in FIG. In the figure, 9 is a region to be sputtered, 10 is a magnetic field,
Reference numeral 11 indicates an electric field formed by a target voltage (usually about 700 volts) applied between the substrate 2 and the target 3, and 12 indicates the movement of electrons in the plasma. Since the plasma is confined on the target surface by the action of the magnetic field 10, it becomes a high-density plasma, allowing a large ion current to flow, and increasing the speed of sputtering. Further magnetic field 1o and city.

Since the field 11 acts orthogonally, the electrons in the plasma are 1
Make a cycloidal motion as shown in 2. Electrons are on substrate 2
Collision with the substrate 2 is reduced, and the temperature rise of the substrate 2 can be prevented.

Such a conventional magnetron type sputtering apparatus can perform sputtering regardless of whether the target material is a magnetic material or a non-magnetic material.

However, when using magnetic material, target material 3
The thickness of the material must be several times the durability.

This is because magnetic materials have higher magnetic permeability than vacuum, so if the thickness 11 is made thicker (usually about 1 m) as in the case of using non-magnetic materials, the plasma will be generated from the plasma focusing magnet. This is because most of the magnetic flux passes through the inside of the target, and the magnetic field acting on the surface of the target 3 becomes extremely weak, making it impossible to make the plasma formed by this magnetic field high density.Therefore, the thickness of the target By making the target thinner, the target's own magnetic circuit-like magnetic resistance is increased, and a high-density plasma is formed by leakage magnetic flux °' that cannot pass through the inside of the target.

However, conventional magnetron sputtering equipment
When sputtering such a magnetic material as a target material, there is a problem that the usage efficiency of the target material is extremely poor, about 1/10, compared to when sputtering a non-magnetic material.

This problem will be explained using FIG. 3. Figure 3 shows the target 3 and plasma focusing magnet 4 shown in Figure 2.
FIG. 3 is a cross-sectional view in the X direction. In the same figure, 13a + 1
4 a + 15 a respectively indicate changes in the intensity distribution of the magnetic field on the surface of the target 30 formed by the plasma focusing magnet 4, and a broken line 13 b.

] 4b and 15b have magnetic field strength distributions of 13a and 14a
It shows the sputtering state of target 3 when +15a. Immediately after the start of sputtering, the magnetic field strength distribution has a convex shape with a gently raised central portion A1, as shown in 13a. Since the high-density plasma formed on the target 3 is focused in accordance with the intensity distribution 13a of this magnetic field, the target 3 is sputtered in a form corresponding to this intensity distribution 13a, and as shown in 13b, the target center B is removed relatively more than the peripheral area. The magnetic resistance at the center of the sputtering target increases compared to the magnetic resistance before sputtering starts because the cross-sectional area of the target center with respect to the magnetic flux passing through the target center is reduced. On the other hand, the magnetic flux φ of the plasma focusing magnet 4 is constant. Therefore, a part of the magnetic flux that has passed through the center of the target until now becomes a small magnetic flux from near the center of the target as the magnetic resistance of the center increases. Therefore, the strength of the magnetic field on the surface of the target center increases,
The intensity distribution of the magnetic field changes from 13a to 14a. That is, since the intensity at the center A2 is further increased, the plasma convergence density near the center of the target is further increased, and the center of the target is sputtered more strongly than the periphery, as shown in 14b. Furthermore, as the sputtering progresses, the above effect is accelerated, and the magnetic resistance at the center of the target increases, causing more magnetic flux to leak from the vicinity of the center, and the magnetic field intensity distribution becomes as shown in 15a. As a result, the target is partially sputtered in the center 15
It will look like b. In this way, when a magnetic material is used as a target, the strength distribution of the magnetic field on the target surface changes over time, and the magnetic field strength at the center of the target increases at an accelerated rate. There is a problem in that the material is partially sputtered and is wasted, resulting in extremely poor material usage efficiency. That is, when the thickness of the target reaches a predetermined value, the target must be replaced. Normally, the usage efficiency of non-magnetic materials is 40
-50 inches, whereas the usage efficiency of magnetic material is less than 4-5 inches.

(Objective of the Invention) This invention was made with attention to the above-mentioned problems, and the above-mentioned problems are solved by changing the magnetic field strength on the target surface inside a plasma focusing magnet according to the sputtering rate of the target. The purpose is to

(Structure and operation of the invention) The present invention will be explained below based on the drawings.

FIG. 4 is a diagram showing an embodiment of the present invention.

This invention provides electromagnets 16 and 17 inside a plasma focusing magnet in a conventional magnetron type sputtering apparatus.
Alternatively, it is a configuration in which high magnetic permeability magnetic materials 18 and 19 are provided. A case in which an electromagnet is provided as a first embodiment, and a case in which a high permeability magnetic material is provided as a second embodiment will be described below.

FIG. 5 is a diagram showing a first embodiment using an electromagnet. For convenience of explanation, the explanation will focus on the magnet on the right side of FIG. The electromagnet 16 is installed inside the plasma focusing magnet 4 so that the direction of magnetic flux generated by passing a current is opposite to the magnetic flux of the plasma focusing magnet. The current flowing through the coil is supplied through terminals h1 and h2.

Next, the effect will be explained. Now, let us consider a situation where the center of the target is sputtered more than the periphery, as shown in FIG. In the conventional device, as mentioned above, the magnetic field strength at the center of the target increases at an accelerating rate due to the increase in magnetic resistance at the center of the target over time, and the center of target 3 becomes polarized as shown in Figure 1j121. Be partially spattered.

When the target 20 is in the state, a current is passed through the electromagnet 16 and the plasma focusing magnet 4 passing through the target center P generates a magnetic flux φ, which decreases over time due to the decrease in the cross-sectional area of the center. Consider the case where magnetic flux φ1 in the opposite direction is applied. At the center P, electromagnet 1 out of the magnetic flux φ
The magnetic flux corresponding to the magnetic flux φ from 6 is canceled out. Therefore, an amount corresponding to φ1 of the magnetic flux that has become a leakage magnetic flux near the center P and forms a surface magnetic field on the target passes through the target center P. In other words,
This means that the magnetic resistance at the target center P has apparently decreased. Therefore, to set the size of φ1 to an appropriate value,
The surface magnetic field on the target has a concave intensity distribution at the center Q as shown in Figure B, and acts almost uniformly over the entire target surface.In other words, the focused state of the plasma also corresponds to this intensity distribution. , the target 3 can be sputtered almost uniformly.The magnitude of the magnetic flux φ is set to an appropriate value by changing it according to the sputtering rate of the target.

Next, a second embodiment using high permeability magnetic materials 18 and 19 will be described based on FIG. 6. Examples of high permeability magnetic materials include materials such as sI''r'1CO (summering cobalt).Now consider the state in which the target 3 is being sputtered as shown at 24 in the same figure.Conventional equipment , the magnetic field intensity distribution will be as shown in 27 and the target will be as shown in 5, as described above.

When the target is in the state 24, if there is a high permeability magnetic material 18 in the center P of the target, the magnetic flux that would have leaked from the vicinity of the center P in the absence of this material will be reduced. , a portion φ2 of which passes through the inside of this material 18. Needless to say, this is because the magnetic resistance based on the magnetic permeability of this material 18 is extremely small compared to vacuum. Therefore, the magnetic resistance of the center P is substantially improved by providing the high magnetic permeability magnetic material 18, and as a result, the amount of leakage magnetic flux from the vicinity of the center P is reduced, and as a result, the magnetic field intensity distribution is 26 As shown in the figure, the center part Q has a concave shape. Change the magnitude of the magnetic flux φ2 according to the sputtering rate of the target. This operation is performed by utilizing the fact that the magnetic permeability μS of the high magnetic permeability magnetic material 18 changes with heat.

(Effects of the Invention) As explained above, according to the present invention, the magnetic field strength on the target surface is changed according to the sputtering rate so that it becomes almost uniform on the target surface, so that the entire target can be sputtered almost uniformly. This makes it possible to increase the usage efficiency of magnetic materials. Furthermore, the relative distance between the sputtered area and the substrate is approximately equal,
The uniformity of the film can be improved by wide-area sputtering, which is a feature of the sputtering method.

[Brief explanation of drawings]

Figure 1 is a structural diagram of a conventional magnetron type sputtering device.
Figure 2 is a diagram for explaining the operation of the device in Figure 1;
The figures are diagrams for explaining the magnetic field strength distribution and the sputtering state when a magnetic material is used as a target in the apparatus shown in Figure 1, Figure 4 is a diagram showing an embodiment of the present invention, and Figure 5 is a diagram showing an embodiment of the present invention. The figure is a diagram for explaining the operation when an electromagnet is used, and FIG. 6 is a diagram for explaining the operation when a high magnetic permeability material is used. 2... Substrate 3... Target 4... Plasma focusing magnet 10... Magnetic field 11... Electric field 16, 17... Electromagnet 18, 19... High permeability magnetic material patent applicant Tokyo Denki Kagaku Kogyo Co., Ltd. Patent Application Agent Patent Attorney Megumi Yamamoto −

Claims (3)

[Claims] (1) High-intensity plasma is formed on the surface of the target by applying an S field orthogonal to the electric field acting between the substrate and the target using a plasma focusing magnet, and the target is sputtered by argon ions in the plasma. In the magnetron type sputtering equipment,
A magnetron type sputtering apparatus characterized in that means for changing the magnetic field strength on the target surface in accordance with the sputtering rate of the target is provided inside the plasma focusing magnet. (2) means for changing the magnetic field strength on the target surface in accordance with the sputtering rate of the target;
2. Device according to claim 1, characterized in that it is an electromagnet. (3) means for changing the magnetic field strength on the target surface in accordance with the sputtering rate of the target;
The device according to claim 1, characterized in that it is a high permeability magnetic material.