JPH11131239A - Plasma CVD film forming method and apparatus - Google Patents

Abstract

(57) [Abstract] [Problem] Without attaching a film formation target to an upper electrode,
Also, a plasma CV capable of reducing the amount of particles taken into the thin film without interrupting the film forming process for a long time
Provision of D film formation equipment. The upper electrode has a large number of source gas ejection pores through which a source gas supplied from a source gas supply pipe passes. The lower surface of the upper electrode is covered with a thin electrode cover 1 having a thickness of 1 mm. The electrode cover 1 is provided with pores 7 having a diameter of 1 mm, which are the same as those of the raw material gas ejection pores, corresponding to the positions of the raw material gas ejection pores. And supplied to the reaction chamber. The screws 3 to 6 fix the electrode cover 1 to the upper electrode. Since the upper electrode is covered with the electrode cover 1, the reaction product deposited on the electrode cover 1 becomes a particle before the electrode cover 1 begins to fall on the thin film growing on the surface of the film formation target.
It is possible to prevent more than a predetermined amount of particles from being taken into the thin film simply by replacing the particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel-plate electrode capacitively coupled plasma CVD film-forming apparatus used for depositing a thin film such as silicon nitride on a surface of a film-forming object such as a semiconductor substrate at a low temperature. In particular, an outlet opening of a source gas supply pipe is in contact with the upper side of the upper electrode, and a source gas ejection hole penetrating the upper electrode is provided, and the source gas is supplied to the reaction chamber through the source gas ejection hole. A plasma CVD film-forming method which has a device for preventing the film deposited on the upper electrode from being peeled off and becoming a so-called particle, falling on a film-forming target during film formation, and preventing the particle from being mixed into the thin film. Related to the device.

[0002]

2. Description of the Related Art As a device for forming a passivation film or the like on a substrate at a low temperature in a semiconductor manufacturing process, there is a capacitively coupled plasma CVD film forming device having parallel plate electrodes. Examples of the passivation film include silicon nitride (Si ₃ N ₄ ) and silicon oxide (SiO ₂ ). In a parallel plate electrode capacitively coupled plasma CVD film forming apparatus, the film deposited on the upper electrode is peeled off during the film forming process to form so-called particles, falls on the growing thin film, and the particles are taken into the thin film, and the It may interfere with the formation of quality thin films. Conventionally, the following two methods have been mainly employed in order to prevent particles from being mixed into the thin film.

The first method is to use a jig also serving as an upper electrode and attach a film-forming target to the jig. In this method, since the thin film grows below the film-forming target, particles falling from above do not reach the film-forming surface, and the particles are not taken into the thin film.

The second method is once interrupted deposited during the deposition process, a method of cleaning a reaction chamber with a cleaning gas such as CF _4. In the method of cleaning the reaction chamber with a cleaning gas, when the film formation is interrupted, the cleaning gas is supplied to the reaction chamber while the supply of the source gas is stopped, and the cleaning gas is subjected to a chemical reaction between the cleaning gas and the deposit. A gas which is a chemical reaction product between the gas and the deposit is generated, the gas is discharged from the reaction chamber, the pressure in the reaction chamber is reduced again to a vacuum, and the film formation is resumed.

[0005]

In the first method described above, since the upper electrode is constituted by a jig to which a film-forming object is attached, it is necessary to manufacture a jig for each film-forming object. This leads to an increase in membrane cost. The jig production in the first method is not so difficult as long as the object to be film-formed has a shape with excellent symmetry such as a circle or a rectangle, that is, a fixed object. If the film object is of any other shape, that is, an irregular shape, it is generally not easy, and the film formation cost is further increased. Not only that,
When the object to be film-formed is attached to the upper electrode, the flow of the raw material gas in the reaction chamber becomes uneven, the film thickness deposited on the object to be film-formed becomes uneven, and the quality of the thin film deteriorates. In addition, when the object to be film-formed is grasped by the jig, a solid of a reactant does not precipitate in a region of the object to be film-formed that is in contact with the jig. Not all regions can deposit a uniform film.

In the above-mentioned second method, when the size of the reaction chamber is an ordinary semiconductor manufacturing apparatus, it takes at least two hours to clean the reaction chamber with a cleaning gas, so that the productivity of the thin film is improved. Obstruction on

Accordingly, an object of the present invention is to provide a plasma CVD method capable of reducing the amount of particles taken into a thin film without attaching a film-forming object to an upper electrode and without interrupting the film-forming process for a long time. An object of the present invention is to provide a membrane method and an apparatus.

[0008]

In order to solve the above-mentioned problems, the present invention provides the following means.

An upper electrode and a lower electrode, each having a plane parallel to the horizontal plane, are provided in the reaction chamber so that the planes face each other, and the upper side of the upper electrode has an outlet opening of a source gas supply pipe. A plurality of source gas ejection pores penetrating in a direction orthogonal to the plane and passing the source gas supplied from the source gas supply pipe are formed in the upper electrode, and the reaction chamber With the pressure reduced to a vacuum, a plasma is generated between the facing planes by applying a high-frequency voltage between the upper electrode and the lower electrode, and a plasma is generated between the upper electrode and the lower electrode through the raw material gas ejection pores. The raw material gas supplied to the substrate is excited by the plasma to cause a chemical reaction on the raw material gas, thereby depositing a solid on a surface of a film formation target such as a substrate disposed between the upper electrode and the lower electrode. In the plasma CVD film forming apparatus for forming the solid thin film, the flat surface of the upper electrode is covered with a thin cover. A plasma CVD film forming apparatus, wherein pores having the same diameter are provided, and means for attaching the cover to the upper electrode comprises attaching and detaching means such as screws and clips for easily attaching and detaching the cover.

The above-mentioned plasma CVD, wherein the cover is made of quartz, silicon or other material and does not discharge gas even in a vacuum space.
Film forming equipment.

An upper electrode and a lower electrode, each having a plane parallel to the horizontal plane, are provided in the reaction chamber so that the planes face each other, and the upper side of the upper electrode is provided with an outlet opening of a source gas supply pipe. The upper electrode was formed with a number of source gas ejection pores that were in contact with, penetrated in a direction perpendicular to the plane, and through which the source gas supplied from the source gas supply pipe passed, and the reaction chamber was evacuated to a vacuum. In this state, a plasma is generated between the facing planes by applying a high-frequency voltage between the upper electrode and the lower electrode, and the plasma is supplied between the upper electrode and the lower electrode through the raw material gas ejection pores. The raw material gas is excited by the plasma to cause a chemical reaction on the raw material gas, thereby depositing a solid on a surface of a film formation target such as a substrate disposed between the upper electrode and the lower electrode. Thin In the plasma CVD film forming method, the flat surface of the upper electrode is covered with a thin cover, and the cover is provided with pores having substantially the same diameter as the source gas ejection pores at the positions of the source gas ejection pores. The supply of the raw material gas is temporarily stopped before the amount of the solid thin film deposited on the surface of the cover peeled off and taken into the thin film formed on the surface of the film formation target reaches a predetermined value. Returning the pressure of the reaction chamber to atmospheric pressure, replacing the cover with a new one, reducing the pressure of the reaction chamber to vacuum again, restarting the supply of the source gas, and The plasma CVD film forming method, wherein the solid is further deposited on the thin film and the thin film is grown.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described.
The present invention will be described in more detail.

FIG. 1 is a bottom view showing an upper electrode structure according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view thereof.
In a parallel plate electrode capacitively coupled plasma CVD film forming apparatus, an upper electrode 2 and a lower electrode are opposed to each other in a reaction chamber at a predetermined distance. The lower surface of the upper electrode 2 and the upper surface of the lower electrode both form a horizontal plane, and these planes face each other. The upper electrode 2 has a disk shape having a thickness of about 5 mm, and has a thickness of 10 mm at the outer edge.
The upper opening of the source gas supply pipe is in contact with the upper surface of the outer edge, and the outer edge of the upper electrode 2 and the outlet edge of the source gas supply pipe are fixed with screws. The upper electrode mounting surface 8 in the figure indicates a contact surface between the outer edge of the upper electrode 2 and the outlet side edge of the source gas supply pipe.

The upper electrode 2 has a large number of raw material gas ejection holes 9 which penetrate in a direction perpendicular to the lower surface thereof and through which the raw material gas supplied from the raw gas supply pipe passes.

The raw material gas ejection pore 9 has a diameter of 1 mm and a diameter of 10 mm.
They are provided at mm intervals. With the pressure in the reaction chamber reduced to a vacuum, a high frequency (for example, 13.56M) is applied between the upper electrode 2 and the lower electrode.
(Hz), a plasma is generated between the opposing planes (the lower surface of the upper electrode 2 and the upper surface of the lower electrode) and supplied between the upper electrode 2 and the lower electrode through the raw material gas ejection pores 9. The generated source gas is excited by the plasma to cause a chemical reaction in the source gas.

The source gases are, for example, SiH ₄ and NH ₃ ,
Si ₃ N ₄ and H ₂ are generated by the reaction between the _two , and Si ₃ N ₄ is a solid.If a Si substrate is placed on the lower electrode,
The solid Si ₃ N ₄ is deposited on the surface of the Si substrate, and a thin film of the Si ₃ N is formed on the surface of the Si substrate. The Si ₃ N thin film becomes a passivation film for protecting the surface of the Si substrate.

The lower surface of the upper electrode 2 is covered with a thin electrode cover 1 having a thickness of 1 mm. The electrode cover 1 is provided with pores 7 having a diameter of 1 mm, which are the same as those of the raw material gas ejection pores 9, corresponding to the positions of the raw material gas ejection pores 9. The gas is supplied to the reaction chamber through the pores 7. Screws 3 to 6 are attached to upper electrode 2 and electrode cover 1
Is fixed. Since the screws 3 to 6 are used to attach the electrode cover 1 to the upper electrode 2, anyone can easily and manually perform the operation of attaching and detaching the electrode cover 1 to the upper electrode 2. Means for attaching and detaching the electrode cover 1 to and from the upper electrode 2 includes:
A clip may be used instead of the screws 3 to 6.

According to the plasma CVD film forming apparatus of the present embodiment, when the film forming process is continued for a predetermined time, the thin film has a thickness such that the reaction product is deposited on the surface of the electrode cover 1. Since the growth is predicted, the supply of the raw material gas is temporarily stopped, the pressure in the reaction chamber is returned to the atmospheric pressure, the electrode cover 1 is replaced with a new one, and the pressure in the reaction chamber is reduced again to vacuum. The supply of gas is restarted, and the reaction product is further deposited on the thin film on the surface of the object to be formed, and the thin film is grown to a required thickness. The relationship data between the duration of the film forming process and the thickness of the reaction product deposited on the surface of the electrode cover 1 can be obtained by trying the film forming process using the present plasma CVD film forming apparatus. The duration of the film forming process until the electrode cover 1 is replaced is determined by the thickness at which the film of the reaction product deposited on the surface of the electrode cover 1 is peeled off and becomes a so-called particle, which begins to fall on the film formation target during film formation. Now choose a time that is shorter than the time predicted from the data that the film has grown.

In this embodiment in which the upper electrode 2 is covered with the electrode cover 1 as described above, the reaction products deposited on the electrode cover 1 become particles and start to fall on the thin film growing on the surface of the film formation target. By simply replacing the electrode cover 1 beforehand, it is possible to prevent particles of a predetermined amount or more from being taken into the thin film. The replacement of the electrode cover 1 is a simple operation of attaching and detaching the screws 3 to 6 and can be performed in 1 to 2 minutes, so that anyone can easily perform the replacement in a short time. There is no need to attach the film-forming target to the upper electrode 2 by using a jig, so that the production cost of the jig is not required and the flow of the source gas is not affected by the jig, so that the thickness of the thin film becomes uniform. Also, there is no problem that a thin film is not formed in a region gripped by the jig. In addition, in this embodiment, no time is required for reacting the cleaning gas with the deposit in the reaction chamber. The interruption time of the film forming process is a time in which the pressure in the reaction chamber is returned to the atmospheric pressure, the electrode cover 1 is replaced, and the pressure in the reaction chamber is reduced again to vacuum. When the size of the reaction chamber is a normal semiconductor manufacturing apparatus, the interruption time of the film forming process is 15 to 20 minutes,
The film formation time can be reduced as compared with the method of cleaning the reaction chamber with a cleaning gas, and the efficiency of the film formation process can be improved.

[0020]

As described above in detail with reference to the embodiments, according to the present invention, a thin film can be formed without attaching a film-forming object to an upper electrode and without interrupting a film-forming process for a long time. It is possible to provide a plasma CVD film forming method and apparatus capable of reducing the amount of particles taken into the substrate.

[Brief description of the drawings]

FIG. 1 is a bottom view showing an upper electrode structure in a plasma CVD film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the upper electrode structure of FIG.

[Explanation of symbols]

 1 ... Electrode cover 2 ... Top electrode 3,4,5,6 Screw 7 ... Pore 8 ... Top electrode mounting surface 9 ... ... Surging pores of source gas

Claims (3)

[Claims] An upper electrode and a lower electrode, each having a plane parallel to a horizontal plane and facing each other, are provided in a reaction chamber, and an upper surface of the upper electrode has an outlet of a source gas supply pipe. Side openings are in contact with each other, a large number of source gas ejection pores penetrating in a direction perpendicular to the plane and passing the source gas supplied from the source gas supply pipe are formed in the upper electrode, In a state where the reaction chamber is decompressed to a vacuum, plasma is generated between the facing planes by applying a high-frequency voltage between the upper electrode and the lower electrode,
Exciting the source gas supplied between the upper electrode and the lower electrode through the source gas ejection pores with the plasma,
A plasma CVD film forming apparatus for forming a solid thin film by causing a chemical reaction in the raw material gas to deposit a solid on a surface of a film forming target such as a substrate disposed between the upper electrode and the lower electrode. In the above, the flat surface of the upper electrode is covered with a thin cover, and the cover is provided with a pore having substantially the same diameter as the source gas ejection pore at the position of the source gas ejection pore. The means for attaching the cover is a detachable means such as a screw or a clip for easily attaching and detaching the cover. 2. The plasma CVD method according to claim 1, wherein said cover is made of quartz, silicon or other material and does not discharge gas even in a vacuum space.
Film forming equipment. 3. An upper electrode and a lower electrode, each having a plane parallel to a horizontal plane and facing the plane, are provided in a reaction chamber, and an upper opening of the upper electrode has an outlet opening of a source gas supply pipe. Are formed in the upper electrode to form a large number of source gas ejection holes that penetrate in a direction perpendicular to the plane and allow the source gas supplied from the source gas supply pipe to pass therethrough, and evacuate the reaction chamber. In a reduced pressure state, a plasma is generated between the facing planes by applying a high-frequency voltage between the upper electrode and the lower electrode, and is supplied between the upper electrode and the lower electrode through the raw material gas ejection pores. The raw material gas is excited by the plasma to cause a chemical reaction on the raw material gas, thereby depositing a solid on a surface of a film formation target such as a substrate disposed between the upper electrode and the lower electrode. Solid thin In the plasma CVD film forming method, the flat surface of the upper electrode is covered with a thin cover, and the cover is provided with pores having substantially the same diameter as the source gas ejection pores at the positions of the source gas ejection pores. The supply of the raw material gas is temporarily stopped before the amount of the solid thin film deposited on the surface of the cover peeled off and taken into the thin film formed on the surface of the film formation target reaches a predetermined value. Returning the pressure of the reaction chamber to atmospheric pressure, replacing the cover with a new one, reducing the pressure of the reaction chamber to vacuum again, restarting the supply of the source gas, and The plasma CVD film forming method, wherein the solid is further deposited on the thin film and the thin film is grown.