JPH0250958A - Film deposition equipment using sputtering method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical field to which the invention pertains] The present invention relates to a film forming apparatus using a sputtering method used for forming a thin film, which is one of the steps in the manufacturing of semiconductor devices, and in particular to a film forming apparatus using a sputtering method that improves the utilization efficiency of a target. Relating to a membrane device.

[Description of Prior Art] Conventionally, sputter film forming apparatuses or boat fishing equipment have been used to form metal thin films such as Afl wiring for semiconductors. Typically, a parallel plate type magnetron sputtering film forming apparatus was used. In this method, the thin film forming substrate is placed on the anode electrode in a position opposite to the target placed on the cathode electrode and parallel to the target. At this time, the anode electrode is electrically connected to ground. Then, high frequency power, mainly 13.56 MHz, is applied to the cathode electrode. Then, plasma discharge occurs between both electrodes. Then, the ions in the plasma or the target material are sputtered,
The target material adheres to the thin film formation substrate to form a thin film. However, in order to increase the film formation speed, it is necessary to concentrate the plasma on the surface of the electrode on which the target is placed, so that the magnetic field covers a portion of the target surface.

For this reason, only the portion of the target surface where plasma is concentrated due to the magnetic field is used for film formation. Also,
Since the sputtered target particles fly in only one direction, the film formation rate is uneven at the stepped portion of the substrate surface. Furthermore, since the substrate on which the thin film is to be formed is exposed to plasma, there are other problems such as being susceptible to plasma damage.

In order to solve these problems, a facing target sputtering method has been proposed. In this method, two planar targets are placed facing each other, a thin film forming substrate is placed outside the facing target, and the surface of the substrate is directed toward the gap between the facing targets. With this method, substrate plasma damage could be greatly reduced.

However, since sputtered target particles leak through the gap between the opposing target and the substrate, problems remain, such as poor target usage efficiency and contamination of the reaction chamber by target particles leaking through the gap between the opposing target and the substrate. Ta.

In order to solve this problem, we proposed a cylindrical target facing sputtering film deposition system in which a cylindrical inner target is placed diagonally to the substrate, and the plasma is confined near the target by an opposing magnetic field, separating it from the substrate. (Japanese Unexamined Patent Publication No. 100176/1983).

Figures 3(1) and 3(2) show the above-mentioned conventional device (Japanese Unexamined Patent Publication No. 63
100176) is a sectional view and a side sectional view illustrating the structure of a cylindrical target facing sputtering film forming apparatus.

In FIG. 3, the vacuum container 1 is evacuated from the exhaust port 3 and
After the pressure is reduced to approximately x 10-'' torr, sputtering residue such as argon (Ar) is introduced from the residue inlet 2 to bring the pressure to several m torr.

Inside the vacuum container 1, aluminum (AIl), copper (Cu
), molybdenum (Mo), tungsten (W), titanium (T i ), silicon (Sl), etc. The cylindrical target 4 is placed electrically insulated from the vacuum vessel 1 with both ends open.

An anode electrode 8 that holds a thin film forming substrate 7 on the outside of the target 4 and approximately perpendicular to the central axis of the cylinder is electrically connected to the ground together with the vacuum vessel 1.

Ions in the plasma generated by applying a negative potential (-500 to -several Kv) to the target 4 from the DC power source 9 sputter the target, forming a thin film on the substrate.

A magnet 5 is placed around the outer periphery of the target 4 to generate lines of magnetic force in a direction parallel to the diameter of the cylinder, confining the plasma,
The density is increasing. Since the part of the target near the magnet has a high plasma density and is easily sputtered, the magnet 5 rotates around the axis of rotation of the cylinder to make the erosion of the target 4 uniform in the circumferential direction, thereby increasing the usage efficiency of the target 4. .

A cooling water canopy 10 for cooling the target is provided around the outer periphery of the target 4.

In such a structure, scattering particles sputtered from the target fly toward the substrate from an oblique direction and are deposited on the side walls of the step, thereby forming a film with good step coverage.

Furthermore, since the gap between the target and the substrate is small, the amount of target particles leaking to the outside of the target and the substrate without contributing to film formation is also very small.

Since the plasma is confined near the target by magnetic lines of force, the substrate is separated from the plasma, which provides the advantage that the substrate is less susceptible to plasma damage.

However, in the conventional cylindrical target facing type sputter film forming apparatus, the lines of magnetic force decrease as they move away from the center of the target toward the ends. For this reason, plasma tends to concentrate at the center of the target cylinder, and target erosion is large at the center of the target cylinder and decreases toward the ends. Therefore, the use efficiency of both ends of the target is poor.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved sputtering film forming apparatus that solves the above-mentioned problems in conventional sputtering film forming apparatuses and enables efficient film formation. It is.

Another object of the present invention is to provide a film forming apparatus using a sputtering method that eliminates the above-mentioned conventional problems caused by target erosion, improves target usage efficiency, and enables efficient film formation. It is in.

[Structure and effects of the invention]

The present invention solves the above-mentioned problems in the conventional sputtering apparatus and achieves the object of the present invention. A target holding cylinder having a polygonal prism-shaped inner surface target and a means for rotating the target relative to the target around the rotation axis of the target, and a plurality of magnets installed in the direction of the rotation axis of the target. The main points are:

The film forming apparatus using the sputtering method of the present invention, which is based on the above points, was completed through the following experiments.

In the conventional device shown in FIG. 3, there is a pair of magnets 5. In place of this magnet 5, five magnets generating equal magnetic fields were arranged at equal intervals.

The erosion shape of the target at this time is shown in FIG. The shaded area indicates the erosion area and the magnet. As with conventional devices, the problem of deep erosion at the center of the target and shallow erosion at the edges of the target was somewhat improved, but not solved.

From the results of Experiment 1, it was found that dividing the magnet 5 is effective to some extent in order to make the erosion depth distribution of the target uniform.

Based on the above, we considered controlling the magnetic field of each divided magnet by the distribution of erosion speed. That is, the laser displacement sensors were arranged on the target surface at equal intervals with magnets that were divided and arranged in the direction of the target's rotation axis, so that the distance between the target surface and the laser displacement sensor could be measured. The above distance changes as the target surface is sputtered during sputtering. Based on this change, the erosion speed is calculated by the CPU, and 5
The magnetic field of the electromagnets located at points where the erosion rate was smaller than the average value was made stronger by comparing the average value of each measurement point. In addition, the magnetic field of the electromagnets located at points where the erosion rate is higher than the average value was made smaller.

As a result, the erosion distribution of the target was greatly improved as shown in FIG. The shaded area in the figure indicates the erosion area of the target and the position of the electromagnet.

The film forming apparatus using the sputtering method of the present invention, which was completed based on the facts obtained through the above experimental results, will be described below with reference to the illustrated embodiments.

That is, FIGS. 1(1) to 1(3) show the details of a film forming apparatus using a sputtering method according to the present invention.

In FIG. 1, 101 is a vacuum container, 102 is a sputtering gas introduction pipe, 103 is an exhaust port, and 104 is an Al1.
A cylindrical target with both ends open made of Cu, Mo, W, Ti, Si, etc., 105 is a target holding cylinder of 104, and 106 is an anode electrode which also serves to hold a substrate on which a thin film is to be grown. Further, 107 is a thin film growth substrate, 108
109 is an electromagnet for generating a magnetic field; 110 is a motor for rotating the electrode 106 and the substrate 107;
indicate rollers for holding and rotating the cylindrical target. Furthermore, 111 is a displacement sensor with a laser for measuring the erosion depth of the target.
2 is a motor for rotating the target 104, 1
13 is a power source for the motor, 114 is a DC power source for plasma generation (a high frequency of 13.56 MHz may be used), and 115 is a
Magnetic field lines 116 created by the electromagnet 109 each indicate a power source for the motor 108. In addition, A in the figure is the first
(3) A power supply circuit of the electromagnet 109 shown in the figure is shown. 11
Reference numeral 7 denotes an A/D converter, which converts the displacement amount measured by the sensor 111 into a digital amount since it is output as a voltage. 118 is an I/F converter, D
This converts the signal from the /A converter 117 into a signal for the CPU. 119 is the CPU, sensor 11
The erosion rate is calculated from the rate of change per unit time of the erosion depth of the target measured in step 1, and the magnetic field of each electromagnet 109 is controlled according to the erosion rate. 120 is an I/F converter that transmits signals from the CPU to the controllers of each electromagnet 109. Then, 121 is the power supply connector 1 of the electromagnet 109.
A roller 122 indicates a power source for each electromagnet 109, respectively.

The film forming operation in the film forming apparatus using the sputtering method of the present invention illustrated in FIGS. 1(1) to 1(3) is performed, for example, as follows. That is, from the exhaust port 3, the vacuum container 101
Exhaust the inside. Next, sputtering gas is introduced into the vacuum container 101 through the sputtering gas inlet 102 .

When a negative potential is applied to the target 104 by the DC power supply 114 while rotating the target 104 and the thin film forming substrate 107, a discharge occurs between the target 104 and the electrode 1060, and plasma is generated. At this time, electromagnet 109
When power is supplied from the power supply circuit A to generate magnetic lines of force 115 within the target, plasma is confined inside the target 104 by the lines of magnetic force 115.

Ionized sputtering particles in the plasma are accelerated by the sheath voltage and sputter onto the target surface. The target material sputtered from the target adheres to the thin film forming substrate to form a thin film.

When sputtering starts, the target 1
Non-uniformity of erosion occurs in the direction of the rotation axis of the target 104 on the surface of the target 104. At this time, the sensor 111 measures the distance from the sensor 111 to the surface of the target 104. CPU1
19 calculates the erosion rate distribution of each sensor 111 measurement point from the rate of change in the distance between the sensor 111 and the target surface per unit time. Then, a signal is sent to the electromagnet power controller 121 for this portion so that the plasma density at the measurement point where the erosion rate is smaller than the average value of this distribution is increased. At measurement points where the erosion rate is greater than the average value, the plasma density is reduced.

In the apparatus of the present invention operated as described above, the plasma density in the rotation axis direction on the surface of the target 104 changes, and the erosion rate is also made uniform.

In the apparatus of the present invention as described above, a magnet having the same shape as the magnet in FIG. 4 can be used in place of the target used above and the electromagnet 109 in FIG. 1. In that case, the distribution of erosion of the target in the direction of the rotation axis is as shown in FIGS. 2 and 4.

An experiment was conducted regarding the usage efficiency of the target according to the present invention and the usage efficiency of the target when using the magnet of the conventional device, and the relationship between the two was shown in Table 1. Table 1
As is clear from the results shown in , it is understood that the device of the present invention provides significantly superior effects compared to conventional devices.

Table 1 [Summary of effects of the invention] As explained above, by installing a plurality of electromagnets perpendicular to the cylindrical axis of a cylindrical target and controlling the magnetic field generated according to the erosion of the target, plasma density can be reduced. It can be adjusted to equalize the erosion in the cylindrical axis direction of the tacket. Then, by rotating the target, the region where plasma is concentrated also rotates on the target surface.

As a result, the erosion of the target becomes uniform in the circumferential direction, and in combination with the above-mentioned effect, the entire surface can be used efficiently.

[Brief explanation of the drawing]

1(1), 1(2) and 1(3) are structural explanatory diagrams of a film forming apparatus using a sputtering method according to the present invention. Note that Figure 1 (1) is a schematic sectional view, Figure 1 (2) is a schematic side sectional view, and Figure 1 (3) is a schematic block diagram of the electromagnet control system. FIG. 2 is a schematic cross-sectional view of the target in the apparatus shown in FIG. FIGS. 3(1) and 3(2) are explanatory diagrams of a conventional sputtering apparatus (Japanese Unexamined Patent Publication No. 100176/1983). Note that FIG. 3(1) is a schematic cross-sectional view, and FIG.
2) The figure is a schematic side sectional view. FIG. 4 is a schematic cross-sectional view of a target when the magnet in the conventional device shown in FIG. 3 is used in the device shown in FIG. FIG. 5 is a schematic cross-sectional view of a target when magnets generating magnetic fields of the same magnitude are used in the apparatus shown in FIG. 1. In FIG. 1, 101 is a vacuum container, 102 is a gas inlet, 103 is an exhaust port, 104 is a target, 105 is a target holding cylinder,
106 is an anode electrode and stage, 107 is a thin film forming substrate, 108 is a motor, 109 is an electromagnet, 110 is a roller for holding and rotating the target, 111 is a laser displacement sensor, 112 is a motor, 113 is a power source for the motor, 114 is a 115 is a DC power supply for plasma, 115 is a line of magnetic force, 116 is a power supply for a motor, 117 is an A/D converter, 118 is an I/F converter, 119 is a CPU, 12
0 is an I/F converter, 121 is a coil power supply controller, and 122 is a coil power supply. In FIG. 3, 1 is a vacuum vessel, 2 is a gas inlet, 3 is an exhaust port, 4 is a target, 5 is a magnet, 6 is a line of magnetic force, 7 is a thin film forming substrate,
8 is an electrode, 9 is a DC power supply, and 10 is a target cooling water canopy.

Claims (4)

[Claims] (1) A target holding cylinder having both ends open, having a cylindrical or polygonal prism-shaped inner surface target, and having means for rotating the target relative to the target around the rotation axis of the target;
A film forming apparatus using a sputtering method, characterized in that a plurality of magnets are installed in the direction of the rotation axis of the target. (2) The film forming apparatus using the sputtering method according to claim (1), wherein the magnet is an electromagnet that can control the strength of the magnetic field. (3) A sensor for measuring the erosion depth in the rotation axis direction of the target, a circuit for calculating the erosion speed from the measurement value of the sensor, and controlling the strength of the magnetic field of the magnet according to the erosion speed. A film forming apparatus using a sputtering method according to claim 1 or 2, comprising a circuit that performs the following steps. (4) Claim 1, further comprising means for holding the thin film forming substrate outside the inner surface target and perpendicular to the rotation axis of the target, and further rotating the thin film forming substrate.
A film forming apparatus using a sputtering method according to 1), (2) or (3).