JPH05102036A - Sputtering system - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a high plasma density and a high sputtering efficiency by maintaining a high gas density in a target gap while maintaining a high vacuum chamber condition. [Configuration] A plurality of targets 1 in the vacuum chamber 12
As a supply source of the film-forming substance, which are arranged to face each other, a pair of adjacent targets is used as an electrode and a high-frequency power source is connected thereto, and a magnetic field is applied orthogonal to the electric field generated by the electrodes. A discharge gas is supplied into the gap formed between the targets. At this time, the gas flow flows from top to bottom along the target, so the electric field, magnetic field,
Since the gas flows are orthogonal to each other, they can be efficiently ionized. Also, since the gap between the targets is open toward the wafer, the sputtered particles are
The step coverage is improved because the light is incident on the surface at an angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus used for thin film formation, and more particularly to a sputtering apparatus used for physical (including chemical auxiliary reaction) thin film deposition in a vapor phase in semiconductor element formation.

[0002]

2. Description of the Related Art In the conventional sputtering technique, in order to obtain a good deposited film, it is necessary to lower the pressure in the chamber as much as possible (high vacuum). This high vacuum lengthens the mean free path of particles and reduces the gas absorption in the deposited film, which improves the film quality, but on the contrary, plasma is less likely to be generated stably and the number of ions for sputtering the target is increased. , The deposition rate will decrease.

In order to solve this problem, a magnetic field is applied in a direction orthogonal to the electric field to utilize the cycloidal motion of electrons to increase the plasma density and prevent the deposition rate from decreasing. This technique is called magnetron sputtering technique. The ideal shape of this magnetron sputtering apparatus is generally called a coaxial cylindrical electrode type magnetron sputtering apparatus, but this shape has a problem when applied to a semiconductor manufacturing apparatus. That is, in FIG. 7, the semiconductor substrate (wafer) is placed on the electrodes, but the wafer is becoming larger with the improvement of the semiconductor technology, and it is inconvenient for a cylindrical electrode in this case.

Therefore, today, in manufacturing a wafer, as shown in FIG.
A parallel plate type sputtering apparatus is generally used as shown in FIG. However, in this case, it is difficult to create a uniform magnetic field on the flat plate-shaped target, and normally, magnets are arranged as shown in FIG. 9 to generate a ring-shaped plasma for use. Sputtering mainly occurs only in this ring portion, and therefore even a large-area target plate has only a part that can be used, and there is a problem that the utilization efficiency of the target is poor. There is also a problem that the deposited film on the wafer is not uniform due to the consumption of the target. Further, as another problem, when a film having a surface having a cross-sectional structure as shown in FIG. 10 (a) is formed by sputtering, the particles are not formed on the wafer as shown in FIG. 10 (b). Since the light is incident from the direction perpendicular to, the scattering at the edge portion becomes large, and finally the film shape as shown in FIG. As described above, the conventional sputtering method is said to be a technique with poor step coverage because the film thickness at the step portion becomes thin and disconnection or the like easily occurs.

[0005]

The present invention eliminates the above-mentioned conventional drawbacks, and (1) by maintaining a high vacuum chamber condition while maintaining a high gas density in a target gap,
High plasma density and therefore high sputtering efficiency (high deposition rate), (2) effective use of the entire target material, (3) improved coverage, (4) larger wafer The purpose is to increase the number of facing targets even if they are made to be easy to handle, and (5) reduce the plasma damage of the wafer without using the susceptor for mounting the wafer as an electrode.

[0006]

According to the present invention, a plurality of targets are arranged in a vacuum chamber so as to face each other as a supply source of a film-forming substance, and power is supplied to the target from a high frequency power source provided outside the vacuum chamber. In addition to supply, give a magnetic field orthogonal to the electric field by this high frequency power supply,
Further, the discharge gas is supplied into the gap formed between the targets. The susceptor on which the semiconductor substrate is placed is rotatable in order to make the film thickness and film quality uniform. Further, in the present invention, a heater for heating the semiconductor substrate to a target temperature and a cooling means for preventing overheating can be provided as needed.

[0007]

1 to 4 show the construction of the present invention in four-sided view. FIG. 1 shows the target bodies arranged in the vacuum chamber as viewed from below (from the wafer side). FIG. 2 is a top view of this device. 3 and 4 are cross-sectional views taken along the lines AA and BB of FIG. 2, respectively.

1 to 4, a sputtering apparatus according to the present invention comprises a target body arranged in a vacuum chamber,
It is composed of a susceptor, a cooling device, a heating device, an external power supply device, a magnetic field device, and the like. The target body of the present invention is composed of a plurality of targets 1. Each of the targets has a trapezoidal shape (see FIG. 5) that tapers toward the wafer 8 placed on the susceptor. That is, the distance between the adjacent targets expands toward the wafer. A target with such a cross-sectional shape
By combining them individually, a pair of targets is formed, and a plurality of target pairs are arranged to form a target body. The target body is in close contact with the water cooling mechanism 2 inside the chamber and can prevent overheating. Gas is supplied from the dispersion tube 5 arranged above the gap formed between the plurality of target pairs via the flow rate controller 6 to the gap. An alternating voltage is applied to each of these targets 1 from a high frequency power source 3 outside the chamber. That is, one and the other of the pair of targets facing each other are used as a pair of electrodes and are connected to a high frequency power source. Further, an electromagnet 4 is arranged outside the chamber so that a magnetic field orthogonal to the electric field applied by the high frequency power source is applied. Below the target body is a susceptor that is rotated by a rotating mechanism 10, on which a wafer 8 is placed. A heater 9 for heating the wafer is provided below the susceptor. Further, the chamber is maintained at a high degree of vacuum by a vacuum pump (not shown) connected to the exhaust hole 11.

Since the voltage applied to the electrode of the target 1 is inverted every half cycle, target charge-up does not occur. Therefore, various materials such as semiconductors and insulators can be used as the target material in addition to the conductor. In FIG. 1, an alternating potential is applied to the opposing targets to create an electric field in the lateral direction of the paper. Further, a magnetic field can be created in the vertical direction of the paper surface by the electromagnet 4 outside the vacuum chamber, an orthogonal electric field and magnetic field can be easily created, and high plasma density can be obtained by utilizing cycloidal motion.

In FIG. 4, gas is supplied into the chamber by a plurality of dispersion tubes 5. A gas having a flow rate controlled by the gas flow rate regulator 6 is caused to flow in the gap portion formed by the facing targets. At this time, the gas flow flows from top to bottom along the target, so the electric field,
Since the magnetic field and the gas flow are orthogonal to each other, the gas can be efficiently ionized. Also, by appropriately adjusting the gas inflow rate of the dispersion tube 5,
It is also possible to raise the plasma density of an arbitrary portion to improve the efficiency of sputtering and finely adjust the uniformity of the film thickness.

Wafer 8 from a plurality of arranged targets
Although the space up to has a large volume and is maintained in a high vacuum, the gas density is relatively high in the gap portion between the targets, and therefore the plasma density is maintained high, and the sputtering efficiency is better than that of the conventional apparatus. As shown in FIG. 5, the space between the targets 1 is formed so as to open toward the wafer, so that sputtering is performed on the entire surface of the target 1, but it is the tip of the target 1 that contributes to film formation on the wafer. Only the part. The particles sputtered in the other parts are redeposited on the facing target and are not wasted. The target material repeats this sputtering and mass transfer due to redeposition, moves to the tip portion of the target, and is finally deposited on the wafer. Further, since most of the particles sputtered from the target are incident on the wafer in an oblique direction, a wafer having a step as shown in FIG. 6 has less scattering at the step and the step coverage is improved. Further, when the wafer 8 is rotated by the wafer rotating mechanism 10, a film having good coverage can be formed on the entire surface of the wafer as shown in FIG. 6 (c).

As can be seen from FIG. 3, the electromagnet 4 of the present invention is preferably divided into three parts in the vertical direction, and periodically, the
It helps to move this target material by changing the strength of the magnetic force in the middle and bottom. As a result, the target material prepared on the entire surface of the target can be effectively used, and the target efficiency can be improved. It goes without saying that the electromagnet is not limited to three divisions.

[0013]

As described above, according to the configuration of the present invention described above,
(1) By keeping the gas density in the gap provided between the targets high while maintaining high vacuum chamber conditions,
A high plasma density can be obtained, and thus a high sputtering efficiency (high deposition rate) can be obtained. (2) The entire target material can be effectively used. (3) Even if the wafer is made larger, it is only necessary to increase the number of facing targets, and it is easy to handle. (4) Since the sputtered particles are obliquely incident on the wafer, the coverage is improved. (5) Since the susceptor on which the wafer is placed is not used as an electrode, plasma damage to the wafer is small. (6) conductors, semiconductors,
All insulator materials are available.

[Brief description of drawings]

FIG. 1 is a plan view of a target of an apparatus according to the present invention, viewed from bottom to top.

2 a top view of a target of the device according to the invention, FIG.

FIG. 3 is a cross-sectional view of the device according to the invention taken along the line AA of FIG.

4 is a cross-sectional view of the device according to the invention along the line BB in FIG.

FIG. 5 is a diagram showing a state of particles moving in a space between targets according to the present invention.

FIG. 6 is a diagram showing a film formation state when the present invention is applied to a wafer having steps.

FIG. 7: Conventional coaxial cylindrical electrode type sputtering device

FIG. 8: Conventional parallel plate type sputtering apparatus

FIG. 9 is a diagram showing a sputtering area and a magnetic field distribution of a target in a conventional parallel plate type sputtering apparatus.

FIG. 10 is a diagram showing a film formation state by a conventional sputtering apparatus.

[Explanation of symbols]

 1 Target 2 Water Cooling Mechanism 3 High Frequency Power Supply 4 Electromagnet 5 Dispersion Tube 6 Gas Flow Regulator 7 Rectifier 8 Wafer 9 Heater 10 Wafer Rotating Mechanism 11 Exhaust Port 12 Vacuum Chamber

Claims (2)

[Claims] 1. A pair of targets, which are arranged in a vacuum chamber so as to face each other as a supply source of a film-forming substance, a high-frequency power source for supplying electric power to the targets, and a discharge for discharging in a gap formed between the targets. A sputtering apparatus comprising: a means for supplying a gas; a magnetic field generating means for applying a magnetic field orthogonal to the electric field generated by the high frequency power source; and a susceptor for mounting a semiconductor substrate. 2. The sputtering apparatus according to claim 1, wherein the gap formed between the pair of targets expands toward the semiconductor substrate.