JPH11312672A - Plasma cvd apparatus, film forming method and cleaning method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a P-CVD device, a film forming method, and a cleaning method, wherein a film of uniform quality can be formed with high productivity without giving damages to an electrode. SOLUTION: A water 107 is placed on a lower electrode 103, and a high-frequency electric power is applied to the lower electrode 103 for generating plasma inside a chamber 101. An upper electrode is arranged at the center, composed of an upper electrode 102 provided with a processing gas supply opening and a double electrode 110 which does not have a gas supply opening, and is arranged around the upper electrode 102 via an insulator 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma CVD apparatus capable of improving film forming characteristics and cleaning characteristics, a film forming method thereof, and a cleaning method.

[0002]

2. Description of the Related Art In recent years, there has been remarkable progress in thin-film applied devices represented by ICs, LSIs, TFT liquid crystals, and the like.
Accordingly, demands for a thin film manufacturing apparatus used for the manufacturing have become severe. For example, there is a strong demand for improvements in uniformity of film thickness and characteristics, reduction in particles, and improvement in productivity due to price competition accompanying high integration.

[0003] A plasma CVD apparatus (hereinafter referred to as a P-CVD apparatus) is a promising thin film device manufacturing apparatus which is excellent in high-speed film formation, low-temperature film formation, step coverage, adhesion, and the like.

Hereinafter, an outline of a P-CVD apparatus and a manufacturing process thereof will be described. Here, a case where a silicon nitride film (SiN film) is formed will be described.
FIG. 4 shows an example of a schematic cross section of the P-CVD apparatus. In the reaction chamber 401, the first
The high-frequency electrode 402 (often referred to as a shower electrode, an upper electrode, and the like; hereinafter, referred to as an upper electrode), and the second high-frequency electrode 403 (also referred to as a heater electrode, a lower electrode, and the like, which also serves as a wafer heater). , A gas exhaust port 405, a wafer transfer mechanism 406, and the like.

[0005] The manufacturing process is as follows. The case where a silicon nitride film (SiN film) is formed will be described. First, a substrate (Si wafer) 407 is transferred from a load lock chamber to a transfer lock (not shown) by a transfer robot (not shown).
It is transferred onto the lower electrode 403 kept at a temperature of ° C. The gap between the upper electrode 402 and the lower electrode 403 is adjusted to a predetermined gap of 5 to 50 mm.

Next, monosilane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ) gas are supplied for 10 to 500 S, respectively.
CCM, 10-500 SCCM, 100-7000 SC
CM inside the reaction chamber 401 through the upper electrode 402
Introduced within. After that, a conductance adjusting valve (not shown) provided in the evacuation system causes
Adjusted to a pressure of 0.1 to 8 Torr,
2, the upper electrode 402 is passed through the high-frequency matching device 411.
Is supplied with electric power of 50 to 1000 W, and the upper electrode 40
Plasma is generated between the second electrode 403 and the lower electrode 403 to form a film. When another film is formed instead of the SiN film, the film is formed by changing the introduced gas (for example,
When forming a silicon oxide film,
A film is formed by a similar process instead of SiH ₄ , N ₂ O, etc.).

When the film is formed, the substrate (Si
A film is formed not only on the wafer 407 but also on the lower electrode 403, the upper electrode 402, the inner wall of the reaction chamber 401, and the like. Although there is a difference in the adhesion strength, these unnecessary films are peeled off as they accumulate, causing an increase in particles on the wafer. Therefore, the reaction chamber 401 is periodically
It is necessary to remove unnecessary films adhered to the inner wall and the internal components.

[0008] As a method of removing the same, a method of performing cleaning by introducing a cleaning gas different from the film-forming gas and generating plasma, which is referred to as dry cleaning or plasma cleaning, is often adopted. Hereinafter, a specific example of dry cleaning is shown and described.

After the film formation is completed by the above-described steps, the inside of the reaction chamber 401 is purged with N ₂ gas, and the wafer 407 is carried out. Then, CF ₄ , C ₂ F ₆ , N
Halogen-based gas such as F ₃ , SF ₆ and, if necessary,
Gas containing oxygen such as O ₂ and N ₂₀ is 10-500S each.
After being introduced into the reaction chamber 401 through the CCM upper electrode 402 and adjusted to a predetermined pressure, high-frequency power is applied to generate plasma. Here, the unnecessary film is
The reaction with the fluorine-based gas turns into a fluoride such as SiF ₄ , and is exhausted and discharged from the reaction chamber 401.

Usually, in a P-CVD apparatus, the above-described dry cleaning is performed each time one to several wafers are formed, thereby suppressing the generation of particles.

Such a dry cleaning technique can improve the operation rate of the apparatus because the reaction chamber can be cleaned without opening the chamber to the atmosphere. In addition, the generation of particles can be suppressed and stabilized by cleaning at a cycle of several sheets or less. For this reason, it is introduced into many P-CVD apparatuses.

Further, as a P-CVD apparatus for improving the uniformity of the film thickness and the film quality of the film formation, the upper electrode is concentrically formed with 3.
There has been proposed a P-CVD apparatus in which a gas introduction pipe and a high-frequency power source are connected to each electrode and each electrode can be independently controlled (Japanese Patent Application Laid-Open No. 08-227880).

[0013]

However, in the above-described process using the plasma CVD apparatus, the upper electrode 40
2 and the size of the lower electrode 403 are almost the same size only slightly larger than the wafer (substrate) used,
Further, controlling the plasma by simply applying high frequency power only to the upper electrode 402 depends on external parameters such as gas pressure and discharge gap length.

For this reason, in the film forming process, the film thickness and film characteristics of the central portion and the peripheral portion of the wafer are distributed, and the area around the wafer where devices cannot be formed becomes large. For example, a SiH ₄ flow rate of 150 SCCM, N
In the case of a SiN film formed under the conditions of an H ₃ flow rate of 70 SCCM, an N ₂ flow rate of 2000 SCCM, a gas pressure of 4 Torr, and a high frequency power of 500 W, the allowable range of the film thickness distribution is ± 3%.
If it is less than 5 mm, an area of 5 mm or more around the periphery cannot be used. As described above, the productivity of the conventional apparatus is low, which causes a problem that the device price increases. This problem is becoming more severe with the stricter tolerance of distribution due to recent miniaturization of devices and the increase in the non-uniformity due to larger diameter wafers.

Another problem is related to the cleaning of the P-CVD apparatus. Unnecessary films adhere to the inside of the reaction chamber due to the film forming process. However, the unnecessary films adhered to the upper electrode 402, the lower electrode 403, and the periphery thereof may be dissipated by heat radiation from the lower electrode 403 or heat from plasma. Since the temperature is 100 to 450 ° C., the unnecessary film has a relatively large adhesive strength and is hardly peeled off. On the other hand, the unnecessary film adhering to the side wall of the chamber, away from the lower electrode 403, has a lower radical activity and a lower surface temperature on the adhering surface. It was easy to peel off.

Therefore, in order to prevent contamination due to peeling of the unnecessary film adhered to the side wall of the chamber, it is necessary to perform cleaning for every one to several wafers.
There is a problem that the productivity of the CVD apparatus is reduced.

Further, in the cleaning process, there is a problem that the plasma region does not sufficiently extend to the side wall of the reaction chamber 401, so that an unnecessary film cannot be sufficiently removed.
For example, C ₂ F ₆ flow rate 100 SCCM, O ₂ flow rate 100 S
CCM, gas pressure 0.6 Torr, 700 W (13.56
When the SiN film in the chamber is etched under the conditions of (MHz), the etching rate distribution has characteristics as shown in FIG. That is, the etching rate is large at the center of the chamber, and the etching rate is low at the periphery (side wall) of the chamber.

As described above, in the conventional P-CVD apparatus,
Since there is a distribution in the cleaning characteristic that the etching rate is low near the side wall of the chamber, cleaning of the side wall portion of the chamber does not easily progress. For this reason, it is necessary to spend a long time for cleaning, and the ratio of the cleaning process time to the operation time of the apparatus becomes large, and the productivity decreases. In addition, since the upper electrode 402 and the lower electrode 403, for which unnecessary film cleaning has been completed, are exposed to over-etching for a long time, the upper electrode 402 and the lower electrode 403 are damaged by plasma. Running costs such as consumable parts cost, material gas cost, power cost, etc., such as 402 and the lower electrode 403 are increased.

The above-mentioned Japanese Patent Application Laid-Open No. 08-227880 has been disclosed.
According to the method described in Japanese Patent Application Laid-Open Publication No. H11-157, the structure of the upper electrode becomes complicated and the price of the apparatus increases, and the upper electrode is one of consumable parts exposed to plasma damage during film formation and cleaning. This also increases running costs. Further, the mechanism becomes complicated and maintenance performance deteriorates. In addition, this publication does not disclose the generation of particles near the side wall of the reaction chamber, the problem of cleaning, and the solution to the problem.

As a cleaning method, Japanese Patent Laid-Open No. 4-99281 discloses that an auxiliary electrode is provided to avoid damage to a film-forming electrode. In such a case, it is necessary to greatly lower the lower electrode and increase the distance from the upper electrode, which has led to an increase in the size of the device. In addition, there are problems in terms of complication of the device in the case of a mobile type, dust generation, discharge stability in the case of a non-mobile type, and the like.

Further, Japanese Patent Application Laid-Open No. 62-287079 discloses that an auxiliary electrode is provided below a lower electrode for the purpose of cleaning a portion where plasma is hardly generated. No consideration is given to the removal of the unnecessary film, and there is no effect in reducing the number of times of cleaning, and there is still a problem that productivity is deteriorated.

The present invention has been made to solve the problems in the P-CVD apparatus described above, and is capable of forming a uniform film, has high productivity, and does not damage electrodes. It is an object of the present invention to provide an apparatus, a film forming method thereof, and a cleaning method.

[0023]

According to a first aspect of the present invention, there is provided a plasma CVD apparatus in which a substrate is placed and a lower electrode serving as one high-frequency electrode for generating plasma in a reaction chamber, and the lower electrode faces the lower electrode. And an upper electrode to which high-frequency power is supplied. The upper electrode is provided in the center, has a first upper electrode having a process gas outlet, and an insulator around the first upper electrode. And a second upper electrode which is not disposed and has no outlet for the process gas.

According to a second aspect of the present invention, there is provided a film forming method using the plasma CVD apparatus according to the first aspect, wherein uniformity is obtained in the thickness and characteristics of a film to be formed at the time of film formation. In addition, the power supplied to each of the first upper electrode and the second upper electrode is adjusted.

According to a third aspect of the present invention, there is provided a cleaning method, wherein a substrate is placed, and a lower electrode serving as one high-frequency electrode for generating plasma in the reaction chamber, a first upper electrode disposed in the center, and a periphery thereof. And a second upper electrode disposed with an insulator therebetween, and an upper electrode to which high-frequency power is supplied between the lower electrode and the second upper electrode.
A method of cleaning a device D, wherein a supply amount and / or a supply time of power to each of a first upper electrode and a second upper electrode are made different.

According to a fourth aspect of the present invention, in the cleaning method according to the third aspect, the supply of power to the first upper electrode and the second upper electrode is temporally shifted, so that the first upper electrode and the second upper electrode are separated from each other. The distance between the upper electrode and the lower electrode is increased when power is supplied to the second upper electrode.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a plasma CVD (P-CVD) apparatus according to an embodiment of the present invention will be described. Device configuration,. Film forming operation,. The cleaning operation will be described in the order.

[0028] 1. Device Configuration FIG. 1 is a schematic sectional view of a P-CVD device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 101 denotes a reaction chamber, and an upper electrode is a central upper electrode 102 which also serves as a gas inlet.
And the upper electrode 110 on the outer peripheral portion separated by the insulator 104
(Hereinafter, for the sake of clarity, the upper electrode at the center is simply referred to as the upper electrode 102, and the upper electrode 110 at the outer periphery is referred to as the double electrode 110). These upper electrode 102 and double electrode 110 are connected to high-frequency power supplies 112a, 112 via high-frequency matching devices 111a, 111b, respectively.
12b. 103 is a lower electrode also serving as a heater, 105 is a gas exhaust port, and 106 is a wafer transfer mechanism (so-called lift pin).

The double electrode 110 and the upper electrode 102 are arranged in a plane at a distance of 5 mm or more (distance L in FIG. 1) by the insulator 104. For this reason, even when the double electrode 110 is connected to the ground, there is little capacitive coupling between the two, and high-frequency power loss hardly occurs. Except for the lower plasma generation space, it is a simple ring-shaped flat plate surrounded by the insulator 104 and has no irregularities or protrusions, so that no abnormal discharge is caused. Further, the insulator 104 is made of a dielectric material such as alumina, and also has a role of suppressing abnormal discharge of the central upper electrode 102 with the chamber upper plate 101a at the ground potential.

The double electrode 110 depends on the size of the reaction chamber 101, but is set as follows in the case of a single-wafer type apparatus corresponding to a 5 to 12 inch wafer. That is,
The distance L1 from the inner wall of the chamber is set to insulation, abnormal (local)
The distance is set to 3 mm or more because it is not so close to suppressing discharge. Further, it is not preferable to make the distance L1 too large in order to increase the original plasma density of the side wall portion and the like, so that it is desirable to set the distance L1 in the range of 3 to 30 mm. The dimensions of the double electrode 110 depend on shape stability, mounting properties, dimensions of the insulator 104, etc., and are 5 to 60 mm in width and 1 to 1 in thickness.
20 mm, more preferably 10 to 40 mm in width and 2 in thickness
Set to 〜１０10 mm. On the other hand, the size of the upper electrode 102 is set to be equal to or larger than the size of the wafer to be formed.

As the constituent materials of the upper electrode 102 and the double electrode 110, materials used for ordinary high-frequency electrodes such as Al, Al-based alloys, and SUS-based alloys can be used. If necessary, alumite treatment, ceramic spraying, fluoridation, etc. Surface treatment such as treatment and plating can also be performed.

As described above, in the P-CVD apparatus of the present embodiment, since the upper electrode is divided into two parts by the insulator 104, the upper electrode 102 at the center and the double electrode 110 at the outer part are formed in the film forming process. Can be controlled independently. By controlling the electric power applied to the upper electrode 102 and the double electrode 110, it is possible to improve the film thickness distribution and the like at the central portion and the peripheral portion of the wafer, which has been a conventional problem.

In addition, unnecessary films (conventionally powdery and easily peeled off) adhering to the side wall of the reaction chamber 101 and the upper plate indicated by A or B in FIG. 1 are reduced by adopting the double electrode of the present embodiment. , And it is difficult to peel off.
Therefore, generation of particles and the like can be suppressed, and precision of production and improvement in productivity can be realized.

The advantages of this embodiment are as follows.
Power supply unit 113 for double electrode 110 and insulator 1
Just add 14 etc., the mechanism will not be complicated,
The present invention solves the problems of the conventional P-CVD apparatus at a low cost, such as not leading to an increase in the size of the apparatus and having no problems such as dust generation due to no drive unit.

-2. Modification In the above embodiment, the upper electrode 102 and the double electrode 110
Are connected to separate high-frequency power supply systems 112a and 112b, but using a single power supply system, a changeover switch is provided to supply high-frequency power to an upper electrode alone, a double electrode alone, or both electrodes. Can be switched by the process. When high frequency is applied to only one high-frequency electrode on the double electrode structure, the high-frequency electrode to which no high-frequency electrode is applied is preferably grounded to the chamber. It may be in a floating state separated from the circuit.

The first high-frequency electrode shown in FIG.
Although the process gas outlet is also used, even if the process gas outlet is a P-CVD device separately provided near the side wall of the reaction chamber 101, the contents of the present embodiment are not changed at all. It is possible.

Further, the double electrode 110 in FIG.
As shown in the enlarged views of FIGS. 2A, 2B, and 2C, it can be modified into various forms.

FIG. 2A shows a state where the double electrode 210a is buried in the insulator 204a. FIG. 2B shows an embodiment in which the semiconductor device is attached without being embedded in the insulator 204b. As shown in both figures, when there is a portion that is not embedded in the insulators 204a and 204b,
It is necessary to take measures for suppressing abnormal discharge by chamfering the R shape or the like shown by b. However, if the same electrode area is obtained, the distance separated by the insulators 204a and 204b can be widened and double Capacitive coupling between the electrodes 210a and 210b and the upper portion of the chamber is reduced, and high-frequency loss is reduced.

FIG. 2C shows a case where a double electrode structure is newly adopted without using the insulators 104 and 204 which are existing components. The outer shape of the chamber becomes large due to the mounting portion of the double electrode 210c, the insulator 214c for the double electrode, and the like, but there are few restrictions such as the mountability of these components and the introduction of high-frequency power. Has advantages.

In addition, even with the above-described various modifications, favorable results were obtained in the film forming distribution characteristics and the cleaning characteristics.

In addition, these modifications can also be achieved by simply adding the power supply unit 113 to the double electrode 110, the insulator 114, and the like, so that the mechanism does not become complicated, and the driving unit does not lead to an increase in the size of the device. It is possible to solve the problems of the conventionally proposed method at a low cost, such as no problem of dust generation and the like.

[0042] Hereinafter, a manufacturing process performed by the manufacturing apparatus according to the present embodiment will be specifically described. Here, a silicon nitride film (Si
An example in which an N film is manufactured will be described.

First, 10 vacuum pumps (not shown) are used.
The substrate (Si wafer) 107 is loaded into the reaction chamber 101 evacuated to mTorr or less from the load lock chamber by a transfer robot (not shown), and is loaded into the reaction chamber.
It is transferred onto the lower electrode 103 maintained at 0 ° C. The gap between the upper electrode 102 and the lower electrode 103 is adjusted to a predetermined gap of 5 to 50 mm.

Next, in the case of a silicon nitride film (SiN film), monosilane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ) gases are respectively supplied with 10 to 500 SCCM, 10
５００500 SCCM, 100-7000 SCCM is introduced into the reaction chamber 101 through the upper electrode 102.

Thereafter, a conductance adjusting valve (not shown) provided in the vacuum evacuation system is used to set 0.1 to 8 To.
Adjust to rr pressure.

Further, from the high frequency power supply 112a to the upper electrode 102 through the high frequency matching unit 111a, 50 to 1000
W power to supply the upper electrode 102 and the lower electrode 103
During this time, a plasma is generated to form a SiN film. At this time, at the same time, the high frequency power
A power of 50 to 1000 W is supplied to the upper electrode 110 through 1b.

In the present embodiment, the discharge by the two upper electrodes divided in this manner can improve the plasma density at the outer peripheral portion of the substrate, which is difficult in the conventional P-CVD apparatus. Can be enhanced by discharging,
As a result, the film thickness distribution and the characteristic distribution can be improved, and the film quality of the portion A and the portion B of the reaction chamber 101 can be strengthened and the generation of particles can be suppressed.

Actually, 800 W in the center and 4 in the double electrode
When a power of 00 W is applied, the film thickness distribution is within ± 1.5% except for a region 5 mm from the outermost periphery, and the film thickness distribution is ± 3% except for a region 2 mm from the outermost periphery. Within. In a conventional P-CVD apparatus, ± 5 mm outside 5 mm
Since the distribution is more than 3% and the distribution is about ± 3% inside,
This embodiment greatly improves the uniformity. Since the film thickness distribution was significantly reduced in this manner, the area in which devices could be manufactured could be expanded, and the number of chips to be obtained was greatly increased.

The following can be considered as a cause of suppressing the film thickness distribution as described above. The double electrode 110 of the present embodiment is a simple high-frequency electrode having no gas blowing function. Nevertheless, the distribution of the film thickness and the characteristics could be suppressed (the film thickness in the outer peripheral portion of the Si wafer 107 could be increased) because the distribution of the radical density activated by the plasma was improved. Conceivable. That is, in this embodiment, the gas flows from the central upper electrode 102 to the side wall of the reaction chamber, and the supply of the material gas is sufficient if a certain flow rate can be secured. It is considered that the uniformity of the film thickness and characteristics was obtained by reinforcing the plasma density near the side wall of the reaction chamber. This has been clarified for the first time by the study of the present inventors.

Further, according to the P-CVD apparatus of the present embodiment, the film quality of the portions A and B of the reaction chamber 101 is strengthened, and the number of films (2 to 3) which can be formed conventionally without cleaning. 2) (4-6 sheets), and the productivity could be improved. This is because, in the present embodiment, the film quality of the portions A and B of the reaction chamber 101 is not changed by heating with a special heater or the like but by 2.
The reason for this is that the controllability can be obtained by the plasma using the heavy electrode 110, but such controllability has been made clear for the first time by the study of the present inventors.

-1. Cleaning Method Although the film formation using the dual electrode 110 of the present embodiment has been described above, the cleaning using the dual electrode 110 will be described below.

FIG. 3 shows a P-CVD apparatus according to the present embodiment in which the flow rate of C ₂ F _{6 is} 100 SCCM and the flow rate of O _{2 is} 100 S.
CCM, gas pressure 0.6 Torr, 700 W (13.56
3 shows an etching rate distribution when the SiN film in the chamber is etched under the condition of (MHz). As shown in FIG. 3, the etching rate is very slow at the center of the chamber and large at the periphery (side wall) of the chamber, showing a distribution characteristic in contrast to that of FIG.

Although a specific cleaning method and the like will be described later, as shown in FIG. 3, according to the present embodiment, the cleaning speed around the chamber is increased by the double electrode 110, and cleaning can be performed efficiently in a short time. . Also,
After the cleaning of the central portion is completed, plasma damage to the central upper electrode 102 and the lower electrode 103 caused by over-etching can be reduced by a method such as discharging only the double electrode 110, and the like.

Next, a cleaning process using a double electrode will be specifically described. Here, a film forming process prior to the cleaning process will also be specifically described. First, the evacuated reaction chamber 10
1, a Si wafer 107 is loaded into the chamber and SiH ₄ (silane), NH ₃ (ammonia),
N ₂ (nitrogen) was 10-500 SCCM, 10-5
The gas is introduced through the upper electrode 102 in a unit of 00 SCCM and 100 to 7000 SCCM, and is adjusted to a gas pressure of 0.1 to 8 Torr by an adjustment valve (not shown) provided in the exhaust system. The substrate temperature is set at 250 to 450 ° C., and the discharge gap (the distance between the upper electrode and the lower electrode) is set at 5 to 50 mm.

Next, high frequency power of 100 to 1000 W is supplied from the high frequency power supply system 112a to the upper electrode, and a SiN film is formed on the Si wafer to a predetermined thickness (film forming process).

After the completion of the film forming process, the Si wafer 107 is carried out via an N ₂ purge or the like. After performing this film forming process 1 to 5 times, dry cleaning of the chamber is performed. The number of film-formed wafers is determined by the contamination inside the chamber and the state of generation of particles.

The dry cleaning is performed in the following procedure. First, in a first step, high-frequency power is supplied only to the upper electrode 102, and an unnecessary film attached to the upper electrode 102 and the lower electrode 103 is cleaned. Then, in a second step, the supply of the high-frequency power to the upper electrode 102 is stopped, and the high-frequency power is supplied only to the double electrode 110 to clean a portion such as the side wall of the chamber, which has been difficult to clean conventionally.

The discharge conditions in the first and second steps are as follows: discharge gap length 5 to 50 mm, C ₂ F ₆ flow rate 10 to 5
00SCCM, O ₂ flow rate 10 to 500 sccm, gas pressure 0.1～5Torr, applying high-frequency power of 100 to 1000
Set within the range of W. Here, the discharge conditions in the first step and the second step may be the same or may be changed. From the viewpoint of cleaning efficiency, it is more preferable that the discharge gap is narrowed to 5 to 30 mm in the first step, and the discharge gap is widened to 10 to 50 mm from the plasma spread in the second step.

The gas pressure in the second step is more preferably a low gas pressure of 2 Torr or less in order to suppress local discharge on the side wall of the chamber and stabilize the discharge. This is for the following reason. The discharge by the double electrode 110 is
No high-frequency circuit is formed by opposing electrodes having an inter-electrode distance adjusted like discharge between the upper electrode 102 and the lower electrode 103, and the opposing ground electrode is a chamber side wall, an exhaust plate (not shown). , Etc., and the like, and a lower electrode. Therefore, when the gas pressure is high, local discharge with a limited region of the side wall of the chamber, which is short in facing distance, is dominant, and it is difficult to obtain the spread of plasma. If the gas pressure is set to 2 Torr or less, a stable discharge can be generated. In addition, this allows the plasma to sufficiently expand, and stable cleaning characteristics can be obtained.

The switching of the cleaning and the detection of the end point may be performed by a time management based on experience, or by using a commonly used cleaning time management function such as emission analysis and pressure analysis.

Next, a specific example of the cleaning result will be described.
The first step cleaning is performed at a C ₂ F ₆ flow rate of 100 to 30.
0SCCM, O ₂ flow rate 100~400SCCM, RF4
The cleaning was performed in the second step at a C ₂ F ₆ flow rate of 100 to 300 SCCM under the conditions of 00 to 900 W, a gas pressure of 0.6 to 2 Torr, and a discharge gap of 10 to 30 mm.
O ₂ flow rate 100-400 SCCM, RF 400-900
W, gas pressure 0.6-2 Torr, discharge gap 20-
When performed under the condition of 50 mm, the cleaning of the chamber side wall and the like can be performed efficiently, the cleaning time can be reduced by 10 to 50%, and the life of the upper electrode, the susceptor, and the like can be 1.5 to 3 times. Could be extended. In addition, the imperfectness of dry cleaning was largely eliminated, and the wet cleaning cycle could be extended 2 to 5 times.

As described above, according to the cleaning method of the present invention, since the cleaning is performed using the double electrode, the electric power applied to the central electrode (upper electrode) is set to be lower, so that the upper electrode can be cleaned. It is possible to suppress the overcleaning of the electrode and to suppress the damage, and at the same time, it is possible to reliably remove the unnecessary film attached to the side wall of the chamber.

-2. Modification Example 1 of Cleaning Method The cleaning method is not limited to the method described in -1 above, and dry cleaning may be performed by, for example, simultaneously applying a high frequency to the upper electrode 102 and the double electrode 110. For example, specifically, the discharge gap is set to 10 to 40 m.
m, the gas pressure is 0.1 to 2 Torr, and the other conditions are the same as those of the above-mentioned cleaning method, and the upper electrodes 102, 2
Dry cleaning may be performed by applying a high frequency to the heavy electrode 110 at the same time.

As described above, the same effect as in the above-described cleaning method was obtained when the central portion and the periphery such as the side wall portions were simultaneously cleaned. In addition, the cleaning of the central portion and the peripheral portion such as the side wall portion can be set to be completed at the same time, thereby eliminating the need for over-cleaning. Therefore, the cleaning time can be reduced as compared with the above-described cleaning method. Further, since the dry cleaning can be performed in a single process, the time for moving the distance between the electrodes and adjusting the gas pressure can be omitted, the time can be shortened, and the process management becomes easy. Further, the upper electrode 102, the double electrode 1
If 10 are connected to separate high-frequency power supply systems, the applied power can be controlled separately and the cleaning speed can be adjusted more.
It can be generally controlled by parameters such as the discharge gap length.

The power to be supplied to the upper electrode 102 and the double electrode 110 is set as follows. That is, 2
If the ratio of the power applied to the heavy electrode 110 is increased, the etching rate with respect to the chamber side wall is increased, and the upper electrode 1
In consideration of the fact that increasing the ratio of the electric power applied to 02 increases the etching rate in the central part, and that if the etching rate in the central part is too high, the damage of the consumable parts increases, and so on. Set.

-3. Modification 2 of Cleaning Method The above-described cleaning method has been described as the periodic cleaning performed after the film forming process is performed 1 to 5 times. Here, in addition to such periodic cleaning, a cleaning method for performing a longer period of cleaning will be described.

Under the process conditions as in the above embodiment, 1
After performing the film forming process for up to five sheets, a conventional cleaning process for the upper electrode 102 alone or a cleaning process as described in -2 above is performed (these cleaning processes are referred to as short-period processes). Write). In this example, after such a film forming process and a short cycle process are repeated a plurality of times, for example, 5 to 50 times,
Cleaning by double electrode 110 (long cycle process)
Is carried out.

In the present embodiment, by introducing a periodic cleaning process using the double electrode 110, the cleaning conditions carried out every one to five sheets can be made more relaxed. In other words, the conventional cleaning process of only the upper electrode 102 does not cause much over-cleaning, and the cleaning by the double electrode 110 may be performed before particles increase, thereby shortening the cleaning time and reducing the plasma damage of consumable parts. Can be
Further, even in the case of the cleaning process described in -2 above, strict condition setting and time management are not required, and the effect of increasing the process margin can be obtained. Further, in the present modification, an effect of further increasing the wet cleaning cycle is obtained, which contributes to an improvement in productivity.

-4. Other Modifications In addition to the above-described cleaning methods, the first step and the second step apply a high frequency to the upper electrode 102 and the double electrode 110 in the first step and the second step. Then, the dry cleaning method of changing the discharge gap length and the gas pressure, in the first step, only the upper electrode 102, and in the second step, the upper electrodes 102 and 2
A dry cleaning method of applying a high frequency to both of the heavy electrodes 110 may be used. The above effects were also obtained by these methods.

The dry cleaning conditions are determined depending on the film forming process conditions including the material gas and the like, the internal configuration of the reaction chamber, and the like. Therefore, the cleaning method of the present invention does not limit various process variations, and by using independent controllability by the double electrode, it is possible to set conditions according to individual conditions, thereby shortening the cleaning time and reducing the plasma. Effects such as damage reduction can be obtained.

In this modification, the upper electrode 10
The two and double electrodes 110 are connected to separate high-frequency power supply systems 112a,
Although connected to 12b, using a single power supply system, a changeover switch is provided, and the supply of high frequency power may be switched by a process, such as the upper electrode alone, the double electrode alone, or both electrodes. . When a high frequency is applied to only one high-frequency electrode of the double electrode structure, the high-frequency electrode to which no high-frequency electrode is applied is preferably grounded to the chamber. However, it may be in a floating state separated from the high frequency circuit.

Further, the first high-frequency electrode shown in FIG.
Although the process gas outlet is also used, even if the process gas outlet is a P-CVD device separately provided near the side wall of the reaction chamber 101, the contents of the present embodiment are not changed at all. It is possible.

Although the above description has been made mainly on the basis of the process relating to the SiN film, the present invention is applicable to a film forming apparatus and a process of SiO ₂ , amorphous Si or the like.
In the embodiment, the plasma CVD apparatus and the method of using the same have been described. However, the present invention is also applicable to a thin film manufacturing apparatus such as a thermal CVD apparatus and an etching apparatus. or,
Even if the device is for semiconductors, liquid crystals, or other thin-film devices such as thin-film solar cells and thin-film magnetic heads, it is a change in the size of the device and the like, and the basic components are not changed. Applicable.

[0074]

As described above, according to the P-CVD apparatus of the present invention, in the film forming process, the film thickness and the characteristic distribution can be made uniform, and the particles can be reduced by controlling the film quality around the chamber. In the cleaning process, effects such as a reduction in cleaning time, a reduction in running cost based on a prolonged life of consumables, and the like are obtained.

As described above, according to the present invention, the generation of particles can be suppressed in the film forming process, and the life of consumables can be extended in the cleaning process, so that the productivity can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration of a P-CVD apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a modified example of a double electrode according to the present invention.

FIG. 3 is a diagram showing an example of a dry cleaning speed distribution by a double electrode in the present invention.

FIG. 4 is a schematic sectional view showing a configuration of a conventional P-CVD apparatus.

FIG. 5 is a diagram showing an example of a dry cleaning speed distribution by a conventional high-frequency electrode.

[Explanation of symbols]

 102 upper electrode (first upper electrode) 103 lower electrode 104 insulator 110, 210a double electrode (second upper electrode) 114, 214 insulator

Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C23C 16/34 H01L 21/302 N (72) Inventor Norioka Hoshi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation

Claims (4)

[Claims] 1. A lower electrode serving as one high-frequency electrode for mounting a substrate and generating plasma in a reaction chamber, and an upper electrode facing the lower electrode and supplied with high-frequency power, A first upper electrode disposed in a central portion and having a process gas outlet; and a first upper electrode disposed around the first upper electrode via an insulator and having no process gas outlet. A plasma CVD apparatus comprising: an upper electrode; 2. The method according to claim 1, wherein the first upper electrode and the second upper electrode are formed so as to obtain uniformity in the thickness and characteristics of the film to be formed at the time of film formation. A film forming method comprising adjusting electric power supplied to each of the upper electrodes. And a lower electrode serving as one high-frequency electrode for generating plasma in the reaction chamber, a first upper electrode provided at a central portion, and a first electrode provided around the lower electrode with an insulator interposed therebetween. An upper electrode, wherein the high-frequency power is supplied between the second electrode and the lower electrode,
A method of cleaning a plasma CVD apparatus, comprising: changing a supply amount and / or supply time of electric power to each of a first upper electrode and a second upper electrode. 4. The cleaning method according to claim 3, wherein the supply of power to the first upper electrode and the second upper electrode is shifted in time, and the first upper electrode and the second upper electrode are electrically connected to the lower electrode. A cleaning method characterized in that the interval between them is widened when power is supplied to the second upper electrode.