JPH04320325A - Semiconductor manufacturing device - Google Patents

Abstract

PURPOSE:To enable contamination due to dust and dirt to be reduced and a process to be stabilized by controlling a potential on a surface of a formed film by a device for forming a conductive thin film of a semiconductor manufacturing device. CONSTITUTION:A conductor for controlling surface potential 12 is installed close to a wafer 11 which is installed within a film-formation device 1 and the formed conductive film 11-3 connects the wafer 11 and the conductor for controlling surface potential 12, thus enabling a surface potential of the formed film 11-3 to be controlled through the conductor for controlling surface potential 12. Since magnetization of wafer surface due to a process can be prevented, adhesion of dust and dirt can be reduced and the potential on a surface of a wafer can be controlled arbitrarily, thus enabling plasma state to be controlled finely and the process to be stabilized.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention controls static electricity around a substrate by controlling the surface potential of the formed film inside the process equipment in a film forming process such as CVD or sputtering in the semiconductor manufacturing process. , relates to a semiconductor manufacturing apparatus that improves process stability and prevents fine particles from adhering to a substrate due to static electricity.

0002

2. Description of the Related Art Conventional film forming process apparatuses do not control the surface potential of the film being formed. In the past, attempts have been made to maintain the wafer at a desired potential through a wafer holding device, but there is not necessarily electrical conduction between the part where the holding device is in contact with the wafer and the formed film. . In other words, a nonconductor film is often formed on the wafer, and after such a nonconductor film is formed, no matter how much the holding device is brought into contact with the underlying surface of the wafer, the nonconductor existing in between will be removed. Since the film is a conductor, the potential on the surface of the film to be formed cannot be controlled.

However, if the potential on the surface of the formed film cannot be controlled, the surface of the formed film may become charged due to the process. For example, most film formation is performed using plasma in a low-pressure atmosphere, but the plasma charges the surface, and since there is a nonconducting film between the formed film and the base, the surface of the formed film is It may have a potential due to this. Such charging of the formed film causes the following disadvantages.

First, there is an increase in dust pollution. Reaction products adhere to the walls inside the device. When such reaction products are separated from the wall surface by various forces, they become dust called flakes. Such dust is usually electrically charged, so if a film formed on the wafer surface is charged with static electricity, the dust is attracted by the resulting electric field and adheres to the wafer.

[0005] Next, there is an increase in process instability. In a plasma process, the plasma state changes slightly depending on the potential of the substrate surface. Therefore, if the surface potential cannot be controlled, the process itself will be insufficiently controlled as a result.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the surface of a formed film from being charged during the process and to control the surface potential of the formed film. An object of the present invention is to provide a means for controlling the surface potential of a polysilicon film, for example, when forming an aluminum film by sputtering or a polysilicon film by CVD.

[0007]

[Means for Solving the Problems] The above object is achieved by bringing the formed film into electrical contact with a conductor and controlling the potential of the conductor. Specifically, there are the following methods.

That is, the first method is to place the conductor in contact with or very close to the wafer so that the formed film is formed so as to connect the surface of the wafer and the surface of the conductor. In this case, since the membrane is electrically conductive, the conductor and the membrane are electrically connected, and the membrane surface potential can be applied through the conductor.

The second method is to bring the conductor into contact with the surface of the film after the film is formed. In this case, during the formation of the film,
Although the surface potential cannot be controlled, it is effective in reducing dust adhesion after film formation.

The third method is to contact a portion of the wafer surface where a nonconductor film is not formed, such as the back surface of the wafer, with the conductor, and to contact a part of the area where a nonconductor film is formed, such as the back surface of the wafer, and to contact a portion of the wafer surface where a nonconductor film is not formed. The formed nonconductor film is removed, and the formed film (
This is a method in which a conductor (conductive) is formed directly on the base of the wafer in that area, thereby creating electrical contact between the conductor that is in contact with the back surface of the wafer, etc., and the formed film through the wafer body. .

[0011]

[Operation] The operation of each component will be explained using one embodiment of the present invention.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. This example is an example of the first method, in which a conductor is placed in contact with or very close to the wafer, and a formed film is formed so as to connect the surface of the wafer and the surface of the conductor. The film forming apparatus 1 of this embodiment is an apparatus that uses RF plasma, and power is supplied to the power electrode 2 from an RF power source 4 and a bias voltage is applied by a DC power source 5. The power electrode 2 is electrically insulated from the wall surface of the device 1 by a nonconductor 3. Wafer 1
1 is placed on a susceptor 8 which is also electrically insulated from the wall of the device 1 by a non-conductor 9.

A conductor 12 for controlling the wafer surface potential is in contact with the side surface of the wafer 11. The conductor 12 is connected to the DC power supply 1
2 controls its potential. Gas necessary for film formation flows in through the gas supply port 6 and is exhausted through the exhaust port 7.

Because of this structure, the conductive film 11-3 formed by this apparatus is formed by connecting the wafer and the conductor 12, as shown in FIG. 1(b).
The -3 potential can be controlled throughout the process through conductor 12.

[0015]

[Embodiments] Since the first embodiment has already been introduced, other embodiments will be explained.

The next embodiment is shown in FIG. This example is an example of the second method, that is, the method of bringing the conductor into contact with the membrane surface after the membrane is formed. In this case, the surface potential cannot be controlled during film formation, but the film surface potential can be controlled after film formation, which is effective in reducing dust adhesion after film formation. The apparatus 1 of this embodiment forms a film using RF plasma as in the first embodiment. The difference from the first embodiment is that the conductor 12 moves linearly, is separated from the wafer 11 during film formation, and comes into contact with the wafer after film formation. The conductor 12 actually has a conductor tip 13 that is a sheath and is held electrically insulated from the sheath, and the tip 13 is connected to the DC power source 10 by a conductive wire 14. The conductor 12 is supported by bearings 17-1 and 17-2, and a magnet 15 is installed at the rear end. A magnet 1 is placed on the outside of the device 1.
A slide magnet 16 is attached to face 5, and when the slide magnet 16 is moved, the conductor 12 moves linearly. Because of this structure, after film formation, the conductor 1
2 toward the wafer 11 to bring the tip 13 into contact with the formed film 11-3 of the wafer 11, thereby controlling the surface potential of the wafer.

A third embodiment is shown in FIG. This is the third method, in which a conductor is brought into contact with a part of the wafer surface where a nonconducting film is not formed, such as the backside of the wafer, and a part of the place where a nonconducting film is formed is used. By removing the nonconductive film that has been removed and forming a formed film (conductive) directly on the base of the wafer in that area, it is possible to connect the conductor that is in contact with the back surface of the wafer through the wafer body. , corresponds to a method of making electrical contact between formed films.

In this embodiment, a conductor 12 is brought into contact with the back surface of the wafer by an electrostatic chuck. In the electrostatic chuck, electricity is supplied to the dielectric 19 from a power source 21 through an electrode 20, and the electrostatic force generated therein brings the dielectric chuck into contact with the wafer. Since the electrostatic chuck is surrounded by the conductor 12 and the wafer, which is also conductive, static electricity generated therein does not escape. The wafer 11 is prepared by removing the nonconducting film 11-2 from a portion 18 of the side surface of the wafer 11 in advance, and then forming the base 1 of the wafer.
Expose 1-1. Originally, the nonconductor film 11-2 is a thin film with a thickness of at most 1 micron or less, so it can be removed by lightly rubbing it. Now, when a film is formed after doing so, as shown in FIG. -3 and conductor 12 are electrically connected through the wafer itself. Therefore, the surface potential of the membrane 11-3 can be controlled through the conductor 12.

[0019]

[Effects of the Invention] During film formation, the potential on the surface of the formed film can be controlled arbitrarily. Figure 5 shows the difference in flake dust adhesion probability when the surface potential is grounded and the entire inside of the device is grounded except during the plasma process, and when only the wafer is charged to 50V. FIG. 5 shows the analysis results assuming that the flake dust is tinged with one electron. The analysis model is a single-wafer type plasma CVD apparatus in which the power electrode is a shower electrode, that is, a type in which a large number of small holes are provided, and gas is supplied through these holes. The analysis is performed when the wafer potential is 0V and 50V, and the wafer is placed with the film formation surface facing upward against gravity, and when the wafer potential is 0V in a vertical process where the wafer is aligned against gravity. I followed three cases. It can be seen that even when the wafer potential is at most 50 V and there is only one charge on a particle, the adhesion probability is ten times greater than when there is no static electricity, especially for submicron particles. Also, large particles can have a large number of charges, so
In fact, even for large particles, the probability of adhesion due to static electricity increases significantly.

[0020] In addition, as another effect, since the surface potential can be controlled during the plasma process, the process can be precisely controlled and the process becomes extremely stable.

[0021]

According to the present invention, it is possible to prevent the surface of the formed film from being charged during the process and to control the surface potential of the formed film.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the state of a wafer before processing in a third embodiment of the present invention.

FIG. 4 Regarding the embodiment shown in FIG. 3, after starting the process,
FIG. 3 is an explanatory diagram showing the state of the wafer after film formation has started.

FIG. 5 is a graph illustrating the effects of the present invention, showing that the probability of dust adhesion increases when wafer charging cannot be controlled.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Film forming apparatus, 2... Power electrode, 10... Power supply for potential control, 11... Wafer, 11-1... Wafer base, 11-2... Nonconductor film, 11-3... Conductor film, 12... Conductor for potential control .

Claims (1)

[Claims] 1. In an apparatus for forming a conductive film in a gas phase by CVD, sputtering, etc., a conductor is brought into contact with a part of a substrate to be processed, and a conductor is formed on the substrate and on the surface of the conductor. A semiconductor characterized in that a film is formed continuously to ensure continuity between the film and the conductor, and the potential of the film can be arbitrarily controlled through the conductor. Manufacturing equipment.