JP2000345334A - Sputtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent puncture of insulation of a dielectric film resulting in scattering of the film in the form of particles by preventing the dielectric film adhered to an adhering protection board from being electrostatically charged when the dielectric film is formed by a sputtering device. SOLUTION: An adhering protection board 19 is floated against upper and lower electrodes 5, 6 and a container 2, and at the backside of the board 19, sealed electrode 11 connected with a container 2 at a narrower spacing than sheath thickness is located so that electrical discharge may not occur between the sealed electrode 11 and the container 2 and also electrical discharge may not occur between the adhering protection board 19 and sealed electrode 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus for forming a thin film, and more particularly to a sputtering apparatus suitable for forming a dielectric, especially a high dielectric substance.

[0002]

2. Description of the Related Art In a process of manufacturing a semiconductor integrated circuit (hereinafter referred to as an IC), various dielectric films are formed. The purpose is, for example, an interlayer insulating film, a mask for etching, selective ion implantation, or selective electrode formation, passivation, a dielectric film of a capacitor, and the like. The material and the film formation method are selected depending on the purpose. For example, various methods such as CVD, vacuum deposition, and sputtering are used. In recent years, barium strontium titanate (hereinafter referred to as BST) or strontium titanate (hereinafter referred to as ST) has been used as a dielectric film of a capacitor for miniaturization of ICs.
It has been studied to form a film by sputtering using a high dielectric substance such as O).

A conventional sputtering apparatus will be described with reference to the drawings. FIG. 2 is a longitudinal sectional view conceptually showing this. In the conventional sputtering apparatus 1, a sputtering chamber 3 is formed by a vacuum-evacuable container 2, and a target 4 is fixedly held on an upper electrode 5 above the sputtering chamber 3. Upper electrode 5
Is electrically insulated from the container 2. The upper electrode 5 has a built-in water cooling mechanism for preventing the temperature of the target 4 from rising, but is not shown.

A lower electrode 6 is disposed below and parallel to the upper electrode 5 below the sputtering chamber 3. And
The lower electrode 6 is electrically connected to the container 2 and is grounded by grounding the container 2. Then, a substrate, for example, a semiconductor wafer 7 is placed on the lower electrode 6. The surface of the lower electrode 6 is covered with an insulator, but is not shown. The lower electrode 6 has a built-in heating mechanism for maintaining the wafer 7 at a predetermined temperature, but is not shown.

Then, a predetermined high frequency power is supplied between the upper electrode 5 and the container (ground) by a high frequency power supply 8 to a predetermined negative DC voltage.
Given under bias.

In order to perform a film forming process using the sputtering apparatus 1, a substrate (for example, a wafer 7) is mounted on the lower electrode 6, and a vacuum is drawn by a vacuum pump (not shown) connected to an exhaust port (not shown). Next, a variable conductance valve (not shown) interposed between an exhaust port (not shown) and a vacuum pump (not shown) while introducing a predetermined flow rate of a predetermined gas (for example, Ar gas) from a gas inlet (not shown). ) Is adjusted to a predetermined pressure. Then, high-frequency power is applied to generate plasma, and the target 4 is sputtered.

Therefore, the components scattered from the target 4 are deposited on the wafer 7 to form a film. The components scattered from the target 4 are not only directed toward the wafer 7 but also directed toward other directions. That is container 2
If it adheres to the inner wall of the substrate and other structures in the sputtering chamber 3 (not shown), it is difficult to clean it. The deposition-preventing plate 9 is made of metal, is electrically connected to the container 2 and is at the ground potential, and is easily detachable so that when the sputtered substance attached to the surface becomes thick, it is removed and cleaned. The deposition-preventing plate 9 can be partially retracted for loading and unloading of the wafer 7, but is not shown.

[0008]

When a dielectric material, in particular, a high dielectric material is deposited by the sputtering apparatus 1 having such a deposition-preventing plate 9, a film is formed also on the surface of the deposition-preventing plate 9,
The surface of the film is charged by receiving charges from charged particles in the plasma in contact therewith. When the amount of charge increases and the voltage increases, if the voltage exceeds the withstand voltage of the film, dielectric breakdown occurs and discharge occurs to the deposition preventing plate 9. At that time, the dielectric material at the place where the discharge is performed becomes a hot water ball if it is soluble, and scatters as a small fragment if it is sublimable. If it adheres to the surface of the wafer 7, it becomes defective as foreign matter adheres. If it flies in the sputter chamber in a state where it is easily peeled off, it will adhere to the subsequent wafer. Such a problem occurs when a dielectric is formed,
Especially in the case of a high dielectric material such as BST or STO, SiO
Dielectric breakdown voltage is lower than that of a dielectric having a low dielectric constant such as ₂ , which often occurs. In addition, since the dielectric constant is high, there are many charged electric charges. Therefore, the discharge energy at the time of dielectric breakdown is large and many particles are scattered. However, such a phenomenon does not occur where a film is formed on the surface of the wafer 7. It is presumed that since the surface of the lower electrode 6 is covered with an insulator and the wafer 7 is in a floating state, no discharge occurs that causes dielectric breakdown of the formed dielectric film. Therefore, it was conceived to install the deposition-preventing plate in a float state. However, when the deposition-preventing plate is in a floating state, discharge may occur between the deposition-preventing plate and the container 2 (indicated by reference numeral 10 in FIG. 2). It was found that the state of the plasma changed and stable film formation could not be performed. Accordingly, the present invention provides a sputtering apparatus in which a film attached to a deposition-preventing plate is charged to prevent dielectric breakdown of the film.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a sputtering method which comprises providing a deposition-preventing plate in a container forming a sputtering chamber, and forming a thin film of a dielectric on a substrate disposed in the container. In the apparatus, the shield plate is made of a metal material and electrically placed in a floating state, and a shield electrode for shielding the shield plate against the inner wall of the container is electrically connected to or grounded to the container. Provided is a sputtering apparatus, wherein the sputtering apparatus is not in contact with the deposition-preventing plate and is disposed close to an interval smaller than the thickness of the sheath. According to the above configuration, since the attachment-preventing plate is made of a float, a dielectric film is formed on the surface of the attachment-preventing plate even if the material is made of a metal which is difficult to be broken or chipped by handling. The dielectric breakdown of the body film and no discharge to the deposition-preventing plate are prevented. Then, a shield electrode is arranged outside the deposition-preventing plate and is fixed at the same potential as the container, so that no discharge occurs in the space between the shield electrode and the container. Since the distance between the shield plate and the shield electrode is equal to or less than the thickness of the sheath, no discharge occurs. Therefore, a stable plasma state is maintained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A sputtering apparatus according to the present invention forms a dielectric (including an insulator). The type is R with a parallel plate type electrode as in the embodiment described later.
The present invention is not limited to the f-sputtering type, and can be widely applied to a magnetron sputtering type using a magnetic force, a plasma sputtering device using a microwave, and the like. The deposition prevention plate in the present invention is made of metal. The proof plate often has to be removed and cleaned, so it is better to be made of metal that is resistant to cracking and chipping. In order to arrange them in a float shape, they may be assembled via an insulator such as ceramic.

The shield electrode is not particularly limited as long as it is conductive, but usually a metal plate such as stainless steel is used. However, since it is arranged close to the deposition-preventing plate, it may be formed in a mesh shape so that the gas can be quickly replaced at the time of gas purging or the like.

[0012]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view conceptually showing the above, and does not show an exact dimensional ratio. The same parts as those of the conventional apparatus shown in FIG. 2 are denoted by the same reference numerals, and the description will be simplified. The sputtering apparatus 20 includes a container 2 forming a sputtering chamber 3, an upper electrode 5 disposed above the sputtering chamber 3 and holding a target 4, a lower electrode 6 disposed below the sputtering chamber 3, and A built-in heating mechanism (not shown), a water cooling mechanism (not shown) for the target 4 built in the upper electrode 5, an exhaust port (not shown) and a vacuum pump connected thereto, a variable conductance valve (not shown), a gas inlet port (not shown), etc. May be the same as the conventional device shown in FIG.

The characteristic point of this device is that the deposition plate 19 is arranged so as to surround the side surface of the space between the upper electrode 5 and the lower electrode 6 opposed thereto, which is the same as that of the conventional device. The difference is that the upper electrode 5 and the lower electrode 6 are electrically floated. The deposition-preventing plate 19 is made of metal, and prevents components scattered from the target 4 from adhering to the inner wall of the container 2 and other structures in the sputter chamber 3 (not shown). In order to assemble the deposition-preventing plate 19 in a float state, a ceramic insulator may be used. Although not shown, the whole or a part of the deposition-preventing plate can be retracted in order to put the wafer 7 in and out. And, it is attached in a state where it can be easily attached and detached for cleaning.

[0014] Another feature of the protection plate 1 is
9 is provided with a shield electrode 11 in the vicinity of the back side. The shield electrode 11 is made of, for example, a stainless steel plate, and is provided so as to shield the adhesion preventing plate 19 from the container 2 and is electrically connected to the container 2. Then, the shield electrode 11 and the deposition-preventing plate 19 are arranged in a non-contact manner and at an interval smaller than the thickness of the sheath so that no discharge is generated therebetween. Although not shown, the whole or a part of the wafer 7 can be evacuated in order to put the wafer 7 in and out, similarly to the deposition prevention plate. At this time, the deposition-preventing plate and the shield electrode may be integrally moved and retracted.

According to this sputtering apparatus, the STO
When a thin film of such a high dielectric substance is formed, the film attached to the deposition-preventing plate is not charged and does not cause dielectric breakdown, and the generation of particles is reduced. Since no discharge occurs between the shield electrode 11 and the container 2 or between the shield electrode 11 and the deposition-preventing plate 19, the film can be stably formed.

[0016]

As described above, according to the sputtering apparatus of the present invention, even if the film adhering to the deposition-preventing plate is charged, no discharge is caused to the deposition-preventing plate with dielectric breakdown, so that the generation of particles is reduced. I do.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a sputtering apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a conventional sputtering apparatus.

[Explanation of symbols]

 2 Container 3 Sputter chamber 7 Wafer (substrate) 11 Shield electrode 19 Deposition plate 20 Sputtering device

Claims (3)

[Claims] 1. A sputtering apparatus comprising: a deposition plate in a container forming a sputtering chamber; and a thin film of a dielectric formed on a substrate disposed in the container. The shield electrode that shields the shield plate against the inner wall of the container is electrically connected to or grounded to the container so that the shield electrode is not in contact with the shield plate and has an interval equal to or less than the sheath thickness. A sputtering apparatus, which is arranged in close proximity. 2. The sputtering apparatus according to claim 1, wherein at least a part of both the deposition-preventing plate and the shield electrode is retractable for taking in and out of the substrate. 3. The sputtering apparatus according to claim 2, wherein said deposition-preventing plate and said shield electrode move together when evacuating.