JPH0941137A - Magnetron sputtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to form films even on the bottom of the fine holes on a substrate by constituting a magnet in such a manner as to have a specific magnetic field distribution on a target surface so that discharge is started with a specific low pressure. SOLUTION: A vacuum vessel 1 is provided with a discharge gas introducing port 2 and a vacuum discharge port 3. The target 4 of the material desired to be formed as films is mounted on a target electrode 5 in the vacuum vessel 1. The substrate 6 is mounted at a substrate holder 7 so as to face the target 4. The target electrode 5 is connected to the negative pole of a DC power source 8. The rear surface of the target electrode 5 is provided with a magnet 9. The magnet 9 is so constituted as to have such magnetic field distribution that the horizontal magnetic field intensity in the position where the perpendicular magnetic field intensity on the target 4 surface attains 0 is >=140 gauss and that the perpendicular magnetic field intensity in the position where the horizontal magnetic field intensity attains 0 is >=60 gauss. The start of the discharge under a low pressure of 10<-2> Pa order is thereby made possible. As a result, the atoms made incident diagonally on the substrate are decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron sputtering apparatus mainly used for forming a thin film on a substrate in a semiconductor or electronic device manufacturing process.

[0002]

2. Description of the Related Art When a thin film is formed on a substrate in a semiconductor or electronic device manufacturing process, a magnetron sputtering method is often used because of its ease of handling and good controllability. As is known, the sputtering method
The target of the substance to be deposited and the substrate are placed facing each other in the vacuum chamber, and a discharge gas such as argon is introduced into the vacuum chamber while maintaining a constant depressurized state in the vacuum chamber. A voltage is applied to cause a discharge, and gas molecules (ions) ionized during discharge are accelerated by a negative voltage and enter the target, knocking out atoms on the target surface,
In this way, some of the atoms that are hit out and jump out in various directions by the cosine law are deposited on the substrate to form a thin film. On the other hand, in magnetron sputtering, a magnet is further provided on the back surface of the target so that electric discharge can be efficiently generated by the magnetic field on the target surface.

FIG. 5 of the accompanying drawings schematically shows the structure of a conventional magnetron sputtering apparatus. A is a vacuum chamber in which a target T of a substance to be deposited is mounted on a target electrode B, and a substrate S is mounted on a substrate holder C facing the target T. A magnet D is provided on the back surface of the target electrode B to generate magnetic lines of force as indicated by reference sign E. An inlet F for introducing a discharge gas into the vacuum chamber A
Also, an exhaust port G for maintaining the inside of the vacuum chamber A at a constant depressurized state is provided. Further, H is a DC power supply, which applies a negative voltage to the target electrode B to cause discharge.

[0004]

In normal sputtering, the distance (T / S distance) between the target and the substrate is 3
It is about 0 to 60 mm. This is because the discharge pressure of normal sputtering is on the order of 10 ⁻¹ Pa, and at this pressure, the distance that can be achieved on the substrate without the sputtered target molecules colliding with the discharge gas molecules is 30 to 60 mm. By the way, in a manufacturing process of a semiconductor or an electronic device, there is a process of filling a fine hole opened in the substrate S by sputtering as shown in FIG. In recent years, this hole has become thinner, and in normal sputtering, since many sputtering atoms are obliquely incident on the substrate, a film is attached only near the opening of the hole (see B in FIG. 6), and finally, C in FIG.
As a result, the hole cannot be completely filled. Therefore, a method is adopted in which the T / S distance is separated by 100 mm or more so that the sputtering atoms are incident on the substrate almost vertically. However, if the T / S distance is increased,
In the conventional 10 ^-1 Pa range, the collision of the sputtering atoms and the discharge gas molecules occurs, and the sputtering atoms do not reach the substrate or obliquely enter the substrate.
^-It is necessary to discharge at ² Pa level.

An example of a magnet used for magnetron sputtering is shown in FIG. This magnet is arranged on the back surface side of the target as shown in FIG. 5, and one of the results of measuring the magnetic field strength on the target surface is shown in FIG. FIG.
The magnetic field strength parallel to the target surface on the target surface, the radial component (B (horizontal)) of the target and the vertical component (B (vertical)) of the target surface are measured from the center of the target to the outer peripheral direction. It was measured while moving. When discharging was performed using this magnet, 3 × 10
^The discharge started only at a high pressure of ^-1 Pa or higher. Further, another conventional example of the magnet used for magnetron sputtering is shown in FIG. 8, and the result of measuring the strength of the magnet is 1
One is shown in FIG. When discharging was performed using this magnet, the discharging started only at a high pressure of 3 × 10 ^-1 Pa or higher.

As described above, it has been recognized that the magnetron discharge occurs only by arranging the magnet on the back surface of the target, but the discharge may not start at a low pressure of the order of 10 ^-2 Pa. Therefore, an object of the present invention is to provide a magnetron sputtering apparatus using a magnet satisfying the strength of a magnetic field capable of initiating discharge at the level of 10 ^-2 Pa.

[0007]

In order to achieve the above object, according to the present invention, a magnetron sputtering apparatus is provided in which a magnet is provided behind a target to be sputtered and a closed loop magnetic field is formed in front of the target. The above-mentioned magnet is a magnetic field such that the horizontal magnetic field strength at the position where the vertical magnetic field strength is 0 on the target surface is 140 gauss or more, and the vertical magnetic field strength at the position where the horizontal magnetic field strength is 0 is 60 gauss or more. It is characterized in that it has a distribution and can start discharge at a low pressure of the order of 10 ^-2 Pa.

[0008]

In the present invention, the horizontal magnetic field strength at the position where the vertical magnetic field strength is 0 on the target surface is 140 gauss or more, and the vertical magnetic field strength at the position where the horizontal magnetic field strength is 0 is 60 gauss or more. Since the magnet is configured to have such a magnetic field distribution, it is possible to start the discharge at the 10 ^-2 Pa level.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 and 2 of the accompanying drawings. A large number of magnets having the shapes shown in FIGS. 7 and 8 were made, and the pressure at which discharge could be started under various magnetic field strengths and magnetic field distributions was investigated. The result is shown in FIG. The horizontal axis of the graph shown in FIG. 1 is the horizontal magnetic field strength at the position where the vertical magnetic field strength is 0 (point A in FIG. 2), and the vertical axis is the position where the horizontal magnetic field strength is 0 (B in FIG. 2). point)
Represents the strength of the vertical magnetic field at. In FIG. 1, the black mark is 10
^Under the condition that the discharge started at ^-1 Pa level, the white mark indicates that the discharge started at 10 ^-2 Pa level. From this result, it can be seen that the horizontal magnetic field strength when the vertical magnetic field strength is 0 is 140 gauss or more, and the vertical magnetic field strength when the horizontal magnetic field strength is 0 is 60 gauss or more. Therefore, in the present invention, since the discharge is started at a low pressure of the order of 10 ^-2 Pa, the horizontal magnetic field strength when the vertical magnetic field strength on the target surface is 0 is 140 gauss or more, and the vertical magnetic field strength when the horizontal magnetic field strength is 0. A magnet having a magnetic field distribution satisfying both conditions of 60 Gauss or more is used. As a magnet satisfying these conditions, the magnet has an outer shape as shown in FIG. 7, and the magnetic field distribution on the target surface has characteristics as shown in FIG. Prepared a magnet with.

[0010]

FIG. 3 shows an embodiment of the present invention. Reference numeral 1 denotes a vacuum chamber, which is provided with a discharge gas inlet 2 for introducing a discharge gas such as argon gas and a vacuum exhaust port 3 for maintaining the inside of the vacuum chamber 1 at a constant depressurized state. In the vacuum chamber 1, a target 4 of a substance to be formed into a film is mounted on a target electrode 5, and a substrate 6 facing the target 4 is attached to a substrate holder 7.
It is attached to. The target electrode 5 is connected to the negative electrode of the DC power supply 8. Further, a magnet 9 is provided on the back surface of the target electrode 5, and the magnet 9 is arranged eccentrically from the center of the target 4 as shown in the figure, and is rotatable about the center of the target by a rotating mechanism (not shown). ing. Regarding the strength of the magnetic field formed on the surface of the target 4 by the magnet 9, the horizontal magnetic field strength when the vertical magnetic field strength is 0 is 140 gauss or more, and the vertical magnetic field strength when the horizontal magnetic field strength is 0 is 60 gauss or more. . The T / S distance is set to 100 mm or more, which is longer than in the case of normal sputtering. On the surface of the substrate 6 to be processed which is arranged so as to face the target 4, a diameter of about 1 μm, as shown in FIG.
A hole 6a having a depth of about 1 to 2 μm (that is, a high aspect ratio) is formed.

The operation of the illustrated apparatus will be described below. In FIG. 3, the vacuum chamber 1 introduces a discharge of argon gas or the like from the discharge gas introduction port 2 while evacuating from the vacuum exhaust port 3, and is maintained at 10 ⁻² Pa level. When a voltage of about 400 to 500 V is applied from the DC power supply 8 to the target electrode 5 while rotating the magnet 9, discharge is started on the front surface of the target 4 and the surface of the target 4 is sputtered. The atoms sputtered in this way jump out in various directions, but since the T / S distance is set longer than in a normal sputtering device, only the atoms that jump out from the surface of the target 4 in a direction nearly perpendicular to the surface of the substrate 6 Can be reached Further, although the T / S distance is long as described above, the pressure is as low as 10 ^-2 Pa, so that the sputtered atoms can reach the substrate without colliding with gas molecules on the way. For this reason, since the atoms are incident on the substrate almost vertically, it becomes possible to form a film on the bottom of the hole 6a formed in the surface of the substrate 6 as shown in FIG.

By the way, in the embodiment of the present invention, the magnet is constructed such that the outside has the N pole and the inside has the S pole as shown in FIGS. 7 and 8. However, the strength of the magnetic field on the target surface is Since the absolute value is a problem, it is possible to configure the magnet so that the outside has the S pole and the inside has the N pole.

[0013]

As described above, in the magnetron sputtering apparatus according to the present invention, the vertical magnetic field intensity of the magnetic field formed on the surface of the target by the magnet is 0.
Since the horizontal magnetic field strength constitutes a magnet to have even field distribution as vertical magnetic field intensity is 60 gauss or more in the horizontal magnetic field strength 0 only 140 gauss or more, the 10 ^-2
It becomes possible to start the discharge with a low pressure in the Pa range. As a result, even if the T / S distance is 100 mm or more, the sputtered atoms do not collide with the discharge gas molecules and are not scattered by the time they reach the substrate. As a result, the number of atoms obliquely incident on the substrate is reduced. As a result, it becomes possible to form a film even on the bottom of minute holes opened on the substrate.

[Brief description of drawings]

FIG. 1 is a graph showing the magnetic field strength of a magnet used in an embodiment of the present invention.

FIG. 2 is a graph showing a distribution state of a magnetic field generated on a target surface by a magnet used in the embodiment of the present invention.

FIG. 3 is a schematic diagram showing a magnetron sputtering apparatus according to an embodiment of the present invention.

FIG. 4 is an enlarged partial cross-sectional view showing a film formation state of holes on a substrate performed by using the magnetron sputtering apparatus of the present invention.

FIG. 5 is a schematic sectional view showing the structure of a conventional magnetron sputtering apparatus.

FIG. 6 is an enlarged partial cross-sectional view illustrating film formation of fine holes on a substrate.

FIG. 7 is a schematic diagram showing an example of a magnet used in a conventional magnetron sputtering apparatus.

FIG. 8 is a schematic diagram showing another example of a magnet used in a conventional magnetron sputtering apparatus.

9 is a graph showing a distribution state of a magnetic field generated by the magnet of FIG.

10 is a graph showing a distribution state of a magnetic field generated by the magnet of FIG.

[Explanation of symbols]

 1 Vacuum Tank 2 Discharge Gas Inlet 3 Vacuum Exhaust 4 Target 5 Target Electrode 6 Substrate 7 Substrate Holder 8 DC Power Supply 9 Magnet

Claims (2)

[Claims] 1. A magnetron sputtering apparatus in which a magnet is provided behind a target to be sputtered and a closed loop magnetic field is formed in front of the target,
A magnetic field distribution is such that the horizontal magnetic field strength at the position where the vertical magnetic field strength is 0 on the target surface is 140 gauss or more, and the vertical magnetic field strength at the position where the horizontal magnetic field strength is 0 is 60 gauss or more. A magnetron sputtering apparatus, characterized in that the above magnet is constituted so that discharge can be started at a low pressure of the order of 10 ^-2 Pa. 2. The magnetron sputtering apparatus according to claim 1, wherein the magnet is arranged eccentrically from the center of the target and is rotatably provided around the center of the target.