JP2634339B2 - Sputtering equipment - Google Patents

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 forming a thin film, and more particularly to a sputtering apparatus used for depositing a physical (including a chemical auxiliary reaction) thin film in a gas phase in forming a semiconductor device.

[0002]

2. Description of the Related Art In a conventional sputtering technique, in order to obtain a good deposited film, it is necessary to reduce the pressure in a chamber as much as possible (high vacuum). This high vacuum increases the mean free path of particles and reduces gas occlusion in the deposited film, thereby improving film quality, but conversely making plasma less stable and reducing the number of ions required to sputter the target. , The deposition rate will decrease.

In order to solve this problem, a magnetic field is applied in a direction perpendicular to the electric field to increase the plasma density by utilizing the cycloid motion of electrons, thereby preventing the deposition rate from decreasing. This technique is called magnetron sputtering technique. Although the ideal shape of this magnetron sputtering device is generally called a coaxial cylindrical electrode type magnetron sputtering device, there is a problem in applying this shape to a semiconductor manufacturing device. That is, in FIG. 7, a semiconductor substrate (wafer) is mounted on the electrode. However, the size of the wafer is increased with the improvement in semiconductor technology, and this is inconvenient in the case of a cylindrical electrode.

[0004] Therefore, today, the wafer is manufactured as shown in FIG.
As shown in FIG. 1, a parallel plate type sputtering apparatus is generally used. However, in this case, it is difficult to generate a uniform magnetic field on the target having a flat plate shape, and usually, a magnet is arranged as shown in FIG. 9 to generate and use a ring-shaped plasma. Spatter is mainly generated only in the ring portion. Therefore, even if the target plate has a large area, only a part of the target plate can be used, and there is a problem that the use 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 wafer having a cross-sectional structure as shown in FIG. 10A is formed by sputtering, a particle is formed on the wafer as shown in FIG. Since the light is incident from the vertical direction, the scattering at the edge portion becomes large, and finally, the film shape becomes as shown in FIG. As described above, the conventional sputtering method is said to be a technique having poor step coverage because the film thickness at the step portion becomes thin and disconnection or the like is easily generated.

[0005]

[Problems to be solved by the present invention] The present invention eliminates the above-mentioned conventional disadvantages, and (1) by maintaining a high gas density in a target gap while maintaining a high vacuum degree chamber condition,
High plasma density can be obtained, so high sputtering efficiency (high deposition rate) can be obtained, (2) Effective use of the entire target material, (3) Improvement of coverage, (4) Wafer is larger It is only necessary to increase the number of opposing targets, and it is easy to cope with it. (5) The object is to reduce the plasma damage of the wafer without using a 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 electric power is supplied to the targets from a high-frequency power supply provided outside the vacuum chamber. And a magnetic field orthogonal to the electric field generated by the high-frequency power supply.
Further, a discharge gas is supplied into a gap formed between the targets. The susceptor on which the semiconductor substrate is mounted is rotatable to make the film thickness and film quality uniform. Further, according to 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 necessary.

[0007]

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

1 to 4, a sputtering apparatus according to the present invention includes a target body disposed in a vacuum chamber;
It consists of a susceptor, a cooling device, a heating device, a power supply device provided outside, a magnetic field device, and the like. The target body of the present invention is composed of a plurality of targets 1. Each target has a trapezoidal shape (see FIG. 5) that tapers toward a wafer 8 placed on a susceptor. That is, the distance between adjacent targets increases toward the wafer. The target having such a cross-sectional shape is 2
A pair of targets is formed by combining the plurality of targets, and a plurality of the 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, so that overheating can be prevented. Gas is supplied to the gap formed between the plurality of target pairs from the dispersion tube 5 disposed above the gap via the flow controller 6. An alternating voltage is applied to each of these targets 1 from a high-frequency power supply 3 outside the chamber. That is, one and the other of the pair of opposed targets are connected to a high-frequency power supply as a pair of electrodes. Further, an electromagnet 4 is arranged outside the chamber so that a magnetic field orthogonal to an electric field applied by a high-frequency power supply is given. A susceptor rotated by a rotation mechanism 10 is provided below the target main body, and a wafer 8 is mounted thereon. 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, the target does not charge up. Therefore, various materials such as a semiconductor and an insulator can be used as the target material in addition to the conductor. In FIG. 1, an alternating potential is applied to the opposing target to generate an electric field in the lateral direction of the paper. In addition, a magnetic field can be generated in the longitudinal direction of the paper by the electromagnet 4 outside the vacuum chamber, an orthogonal electric field and magnetic field can be easily generated, and a high plasma density can be obtained by utilizing cycloid motion.

In FIG. 4, a gas is supplied into the chamber by a plurality of dispersion tubes 5. A gas having a flow rate controlled by the gas flow controller 6 flows through a gap formed by the opposing targets. At this time, the gas flows from top to bottom along the target,
Since the magnetic field and the gas flow are orthogonal to each other, the gas can be ionized efficiently. Also, by appropriately adjusting the gas inflow amount of the dispersion tube 5,
It is also possible to increase the plasma density of an arbitrary part, improve the efficiency of sputtering, and fine-tune the uniformity of the film thickness.

From a plurality of arranged targets to a wafer 8
The space up to the target has a large volume and is kept in a high vacuum, but the gas density is relatively high in the gap between the targets, so that the plasma density is kept high and the sputtering efficiency is better than that of the conventional apparatus. As shown in FIG. 5, since the space between the targets 1 is formed in a shape that opens toward the wafer, 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 part. Particles sputtered elsewhere are not wasted because they are redeposited on the opposing target. The target material is moved to the front end portion of the target by repeating the mass transfer by the sputtering and the redeposition, and is finally formed on the wafer. In addition, since most of the particles sputtered from the target enter the wafer from an oblique direction, in a wafer having a step as shown in FIG. 6, scattering at the step is small, and the step coverage is improved. Further, when the wafer 8 is rotated by the wafer rotating mechanism 10, a film with good coverage can be formed on the entire surface of the wafer as shown in FIG.

As can be seen from FIG. 3, the electromagnet 4 of the present invention is preferably divided into three parts in the vertical direction.
The middle and lower magnetic force can be changed to help move this target material. As a result, almost all of the target material prepared on the entire surface of the target can be effectively used, so that the target efficiency can be improved. Of course, the electromagnet is not limited to three divisions.

[0013]

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 the 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 used effectively. (3) Even when the size of the wafer is further increased, it is only necessary to increase the number of opposed targets, and the response is simple. (4) Sputtered particles enter the wafer obliquely, so coverage is improved. (5) Since the susceptor on which the wafer is mounted is not used as an electrode, plasma damage to the wafer is small. (6) conductors, semiconductors,
All insulator materials are available.

[Brief description of the drawings]

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

FIG. 2 is a top view of a target of the apparatus according to the present invention.

3 is a cross-sectional view of the device according to the invention, taken along line AA in FIG. 2;

FIG. 4 is a sectional view of the device according to the invention, taken along line BB in FIG. 2;

FIG. 5 is a view 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 a step;

FIG. 7 shows a conventional coaxial cylindrical electrode type sputtering apparatus.

FIG. 8 shows a conventional parallel plate type sputtering apparatus.

FIG. 9 is a diagram showing a sputtering region 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]

 DESCRIPTION OF SYMBOLS 1 Target 2 Water-cooling mechanism 3 High frequency power supply 4 Electromagnet 5 Dispersion tube 6 Gas flow controller 7 Rectifier plate 8 Wafer 9 Heater 10 Wafer rotation mechanism 11 Exhaust port 12 Vacuum chamber

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-55379 (JP, A) JP-A-57-158380 (JP, A) JP-A-1-191776 (JP, A) JP-A 57-158 76185 (JP, A) JP-A-53-119284 (JP, A) JP-A-2-110919 (JP, A)

Claims (2)

(57) [Claims] A vacuum chamber; a susceptor for mounting a semiconductor substrate disposed in the vacuum chamber; a susceptor disposed in the vacuum chamber as a supply source of a film-forming substance; and a cross-sectional shape disposed on the susceptor. A target main body in which a plurality of target pairs tapering toward the semiconductor substrate are arranged facing each other with a gap therebetween, and a plurality of target pairs having an inclination open toward the semiconductor substrate are arranged, and the plurality of target pairs are formed. A sputtering apparatus comprising: means for supplying a discharge gas through a gap; a high frequency power supply for supplying power to the plurality of target pairs; and a magnetic field generating means for applying a magnetic field orthogonal to an electric field generated by the high frequency power supply. 2. A vacuum chamber, at least one pair of targets disposed opposite each other with a gap provided as a supply source of a film-forming substance in an upper part of the vacuum chamber, and a vacuum separated from the target by a space. A susceptor for mounting a semiconductor substrate disposed in a lower part of the chamber; a means for supplying a discharge gas flowing through a gap formed in the pair of targets from above to below the pair of targets; A high-frequency power supply that supplies electric power to the target, the high-frequency power supply providing an electric field orthogonal to the flow of the discharge gas, and the direction of the flow of the discharge gas and the direction of the electric field by the high-frequency power supply. And a magnetic field generating means for applying a magnetic field orthogonal to the magnetic field.