JPH11233292A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide superior film formation or etching characteristics by setting the cross sectional shape of an exhaust path, which is provided in a vacuum chamber connected to an exhaust port, to an approximately triangle shape, by preventing abnormal discharge such as a local discharge of a plasma processing device before happening, and by stably discharging. SOLUTION: A plasma CVD device is provided with a vacuum chamber 1, a shower electrode 2 also served as a gas leading port, a bottom electrode 3 also served as a heater, a gas exhaust port 6, and a wafer transfer mechanism 7. The vacuum exhaust path 5 is formed into an approximately triangle cross section with an exhaust baffle 4, a side wall and a bottom of the vacuum chamber 1 set to respective sides. This constitution can expand the distance to the bottom electrode 3, and the acute angle part is not positioned near the bottom electrode so as to prevent abnormal discharge such as a local discharge, thereby providing the stable discharge A simple method for inserting the vacuum exhaust baffle 4 can constitute such a vacuum exhaust path as holding a long relative distance to the bottom electrode 3 and suppress the abnormal discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, and more particularly, to a vacuum exhaust path formed in a vacuum chamber.

[0002]

2. Description of the Related Art In the production of thin film applied devices represented by ICs, LSIs, TFT liquid crystals, etc., a plasma CVD apparatus (hereinafter referred to as a P-CVD apparatus), a sputtering apparatus,
Various plasma processing apparatuses such as an etching apparatus are used.

[0003] For example, a plasma 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.

FIG. 4 is a schematic sectional view showing an example of a P-CVD apparatus. In a vacuum chamber 1, a shower electrode 2 also serving as a gas introduction unit and a lower electrode 3 also serving as a wafer heater are provided to face each other. The vacuum evacuation system includes a vacuum evacuation baffle 4 for limiting the vacuum evacuation path in the vacuum chamber 1, a vacuum evacuation path 5 formed by the inner wall of the vacuum chamber 1, a gas evacuation port 6 provided below the vacuum chamber 1, and evacuation. Opening / closing valve 8 for exhaust path provided in piping path, exhaust conductance adjusting valve 9, and vacuum exhaust pump 1
0 or the like.

A wafer 15 is transferred from the load lock chamber to a lower electrode 3 maintained at 250 to 450 ° C. by a transfer robot (not shown), and adjusted to a predetermined discharge gap length of 5 to 50 mm. Next, a silicon nitride film (S
In the case of an iN film), monosilane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ) gas are 10 to 5 respectively.
00 SCCM, 10-500 SCCM, and 100-
7000 SCCM is introduced into the vacuum chamber 1 through the shower electrode 2. Thereafter, the conductance adjusting valve 9 provided in the vacuum evacuation system is used to set 0.1 to 8 To.
rr is adjusted to a pressure of 50 to 1000 W from the high frequency power supply 12 to the shower electrode 2 through the high frequency matching device 11.
13.56 MHz high frequency power is supplied to generate plasma between the shower electrode 2 and the lower electrode 3 to form a film.

In the case of a silicon oxide film, the same process is performed only by changing the introduced gas to SiH ₄ , N ₂ O or the like.

[0007] In the above, the process gas introduced from the shower electrode 2 is provided on the evacuation baffle 4 at substantially equal intervals as indicated by arrows A in FIG.
The gas passes through the two holes 4 a and the evacuation path 5, and is drawn from the evacuation port 6 to the evacuation pump 10. By providing the evacuation baffle 4 in this manner, the process gas introduced from the shower electrode 2 into the vacuum chamber 1 isotropically directed to the evacuation port, and the distribution in the surface of the wafer 15 is improved. .

[0008]

However, a film formed by such a method usually has residual film stress depending on the film forming process conditions. Such residual stress (hereinafter, simply referred to as stress) becomes warpage of the wafer, causing damage to the device such as wafer cracking, cracking, film peeling, and other obstacles such as pattern displacement. These obstacles have become more and more important issues with the recent increase in diameter and miniaturization of wafers. Specifically, the film stress is set to 1E + 08 to 1E + 09dy.
Process conditions, device mechanisms, and the like that control the compression stress to n / cm ² or less have been required.

Conventionally, such stress control has been performed by using process parameters such as input RF power and discharge gas pressure, and a low-frequency bias of 50 to 500 kHz is applied to the lower electrode 3 on which the wafer 15 is mounted. A method of applying the voltage has been proposed. Stress control by low frequency bias
13.56 MHz for the shower electrode 2 which is usually used
This method is one of the promising methods in which the number of parameters that can be controlled independently increases by one compared with the method of applying the high frequency and controlling by the process parameters such as the electric power and the gas pressure. However, when high-frequency power is applied to the lower electrode 3 which has conventionally been a chamber grounding electrode at a relatively low frequency of 50 to 500 kHz, the evacuation including the evacuation baffle 4 provided near the lower electrode 3 is performed. Locally or between the chamber earth ground potential component constituting the path 5 or
The problem that an overall discharge occurs has arisen. This means that the distance between the lower electrode 3 and the evacuation path 5 is relatively short in comparison with the distance between the shower electrode 2 and
It is considered that since the cross section of the exhaust path is substantially rectangular, a sharp corner of about 90 degrees is located near the lower electrode 3 and local discharge easily occurs.

For this reason, a method of increasing the size of the vacuum chamber 1 to increase the distance between the vacuum exhaust path 5 and the lower electrode 3 or canceling the formation of the vacuum exhaust path 5 and performing vacuum exhaust directly from the gas exhaust port 6, A method of forming the component of the passage 5 with a ceramics component such as alumina is used. However, these countermeasures have caused new problems such as an increase in the size of the device, an increase in the device manufacturing cost, and an increase in the footprint (device installation area). Further, in order to cancel the formation of the vacuum exhaust path 5 and to make the gas flow uniform, it is necessary to provide a plurality of gas exhaust ports 6, which complicates the apparatus configuration and, in some cases, increases the size. . In addition, forming the vacuum evacuation path 5 using a ceramic material such as alumina as a component increases the manufacturing cost of the apparatus.

In a typical reactive etching apparatus, high-frequency power of 13.56 MHz is applied to a lower electrode which also serves as a wafer holding table. Has been a problem, and has been dealt with by the above-described method, and has a similar problem.

[0012]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a parallel plate type high frequency electrode for generating plasma in a vacuum chamber capable of maintaining a vacuum state, and a process therefor. In a plasma processing apparatus having a gas outlet and a gas exhaust port connected to a vacuum exhaust facility, a plasma is characterized in that an exhaust path provided in a vacuum chamber connected to the exhaust port has a substantially triangular cross-sectional shape. Processing device.

According to a second aspect of the present invention, the exhaust baffle having a substantially inverted C shape is formed along the inner wall of the vacuum chamber, and the sectional shape is made substantially triangular. Is a plasma processing apparatus.

According to a third aspect of the present invention, in the plasma processing apparatus according to the second aspect, the exhaust baffle plate has a slit-shaped vacuum exhaust hole extending substantially over the entire circumference of the chamber. is there.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a P-CV according to a first embodiment of the present invention.
It is a schematic sectional drawing of D apparatus. In FIG. 1, 1 is a vacuum chamber, 2 is a shower electrode also serving as a gas inlet, 3 is a lower electrode also serving as a heater, 6 is a gas exhaust port, and 7 is a wafer transfer mechanism (a so-called lift pin). The vacuum evacuation path 5 is formed in a shape having a substantially triangular cross section, each of which has a side of the evacuation baffle 4, the side wall of the vacuum chamber 1, and the bottom surface.

The vacuum exhaust path 5 is connected to a gas exhaust port 6, an exhaust path opening / closing valve 8, an exhaust conductance adjusting valve 9, a vacuum exhaust pump 10, and the like. The exhaust baffle 4 has a diameter of 5 to 30 in consideration of the exhaust conductance and to make the gas flow in the vacuum chamber 1 uniform.
Four to sixteen mm holes 4a are formed at regular intervals in the circumferential direction. The shower electrode 2 is connected to a 13.56 MHz high frequency power supply 12 via a high frequency matching device 11. Further, the lower electrode 3 is connected to a low-frequency power source 14 that can be varied from 50 to 500 kHz through a low-frequency matching unit 13 so that a low-frequency bias can be applied.
Although not shown, the shower electrode 2 is provided with a low-frequency path, and the lower electrode 3 is provided with a high-frequency path.

FIG. 2A shows an example of the exhaust baffle 4 used in FIG. The exhaust baffle 4 of FIG. 2 (A) has a substantially inverted C-shaped cross section, and if it is inserted along the inner wall of the vacuum chamber 1 as shown in FIG. Can form a substantially triangular evacuation path 5. The exhaust baffle 4 shown in FIG. 2 (A) is bent (4b, 4c) to stabilize the installation of the side wall or both ends in contact with the bottom surface of the vacuum chamber 1 and suppress the gap.
There is no problem even if it is straight.

By a simple method of inserting the evacuation baffle plate 4 having such a structure, a vacuum evacuation path capable of increasing the relative distance from the lower electrode 3 can be formed, and abnormal discharge such as local discharge can be suppressed.

Since the exhaust baffle 4 is basically formed in such a shape as to suppress local discharge, ceramic materials such as alumina can be used, and metal materials such as Al, Al alloy, and Fe alloys such as SUS can be used. It is. Therefore, there is no need to use expensive parts such as ceramics, and the handling becomes easy. Further, the metal exhaust baffle 4 may be subjected to a surface treatment such as an alumite treatment, a fluoridation treatment, a ceramic spraying, and a plating, if necessary, in order to increase the plasma resistance. A hole 4a formed in the exhaust baffle 4
Although holes of the same size are formed at equal intervals, it is also possible to change the size of the holes or change the interval depending on the positional relationship with the gas exhaust port below. The diameter and the number of holes provided in the exhaust baffle 4 are not limited to those in the above-described embodiment, but may be designed as long as the gas flow is made uniform in consideration of the exhaust conductance.

A film forming process using the P-CVD apparatus shown in FIG. 1 will be described. First, the Si wafer 15 is carried into the evacuated vacuum chamber 1, and SiH ₄ (silane), NH ₃ (ammonia), and N ₂ (nitrogen) are each used as a process gas for film formation at 10 to 500 SCCM,
The gas is introduced through the shower electrode 2 at 0 to 500 SCCM and 100 to 7000 SCCM, and is adjusted to a gas pressure of 0.1 to 8 Torr by an exhaust conductance adjusting valve 9 provided in the exhaust system. The substrate temperature is 250 to 450 ° C., and the discharge gap (the distance between the shower electrode 2 and the lower electrode 3) is
It is set to 5 to 50 mm. Thereafter, a high frequency power of 13.56 MHz is supplied from the high frequency power supply system 12 to the shower electrode 2 through the high frequency matching unit 100 at 100 to 1000 W, and a low frequency power of 14 to 50 kHz is supplied to the lower electrode 3 from the low frequency power supply 14 through the low frequency matching unit 13. Supply 50 to 1000 W of low frequency power. At this time, PC of this embodiment
In the VD device, the lower electrode 3 and the evacuation path 5 or the evacuation baffle plate 4 are sufficiently separated from each other, and between the shower electrode 2 and the lower electrode 3 facing each other without causing local discharge between them. Discharge was able to occur. Further, the process gas introduced into the vacuum chamber 1 from the shower electrode 2 through the plurality of exhaust holes 4 a provided in the baffle plate 4 forming the exhaust path 5 flows uniformly over the wafer 15 from the shower electrode 2, and the film thickness distribution Excellent film thickness distribution of ± 3-5% or less,
The formation of an SiN film having a small and controlled compressive stress of 1E + 08 to 1E + 09 dyn / cm ² was also possible.

Although the working of the inner wall of the vacuum chamber 1 is not particularly performed in the present embodiment, a mechanism for stably installing the exhaust baffle 4 may be provided. In order to increase the area of the exhaust path 5 and reduce the exhaust conductance, it is also possible to cut a part of the inner wall of the vacuum chamber 1 forming the exhaust path 5. or,
A cross-sectional shape having a curved line, such as a case where R machining is used for corner machining of the bottom of the vacuum chamber 1 constituting the evacuation path 5, may be used.

FIG. 2B shows an exhaust baffle 4 according to a second embodiment of the present invention. 0.5 to 5 m above the exhaust baffle 4
A slit-shaped vacuum exhaust hole 4e having a width of m is provided. Due to the structure, there is a part 4f where the slit can be cut at 2 to 6 places,
Exhaust path 5 over the entire circumference of such a vacuum chamber 1
The gas flow can be isotropically guided into the vacuum exhaust path without gathering at the limited exhaust port 6 due to the formation of. As a result, the film thickness distribution shown in the first embodiment is further improved, and a distribution of ± 0.5 to 2% or less is obtained.
The area where the device can be manufactured in the outer peripheral portion of the device can be expanded.

FIG. 3 is a schematic sectional view when the plasma processing apparatus of the present invention is applied to a reactive ion etching apparatus.

The basic structure of the apparatus is the same as that of the P-CVD apparatus shown in FIG. 1, but a high-frequency power supply 12 is connected to the lower electrode 3 which also serves as a wafer holding electrode. Vacuum exhaust path 5
Uses an exhaust baffle plate 4 as shown in FIG. 2 (A) or (B) to increase the distance to the lower electrode 3 to suppress local discharge and the like.

A fluorine-containing gas such as CF ₄ , C ₂ F ₆ and NF ₃ and a gas containing oxygen such as O ₂ and N ₂ O are passed through the shower electrode 2 into the vacuum chamber 1 if necessary. And adjusted to a gas pressure of 0.01 to 1 Torr;
When a high frequency power of 100 MHz to 1000 W of 56 MHz is supplied to the lower electrode 3 and the SiN film or the SiO ₂ film is etched, excellent characteristics with etching uniformity of ± 3% or less without causing local discharge. Obtained.

In this embodiment, the case where high-frequency power including low-frequency is applied to the lower electrode 3 has been described. However, even if the lower electrode 3 is a device having a chamber ground potential, it can be used. Needless to say.

As described above, in each embodiment of the present invention, SiN is mainly used.
Although the explanation has been based on the process relating to the film, SiO ₂ ,
The present invention is also applicable to a film forming apparatus made of amorphous Si or the like and a reactive etching apparatus. In each of the embodiments, the main discharge is the high-frequency discharge of 13.56 MHz. However, the present invention can be applied to a discharge at a low frequency of 50 kHz or a microwave. In particular, in recent years, an insulating film forming apparatus using high-density plasma uses a bias CVD method for embedding a fine pattern and for flattening, and the exhaust path and the exhaust baffle plate according to the present invention are effective. is there. Also, 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, changes in the size of the device, etc., and the basic components remain unchanged. The invention is applicable.

[0029]

As described above, in the plasma processing apparatus of the present invention, the cross-section of the vacuum exhaust path in the vacuum chamber connected to the gas exhaust port has a substantially triangular shape, so that the distance to the lower electrode can be increased. An acute angle such as a substantially rectangular shape is no longer present near the lower electrode, and an abnormal discharge such as a local discharge is suppressed, and a stable discharge is obtained.
Alternatively, a plasma processing apparatus having etching characteristics can be obtained. Further, in the plasma processing apparatus according to claim 2, since the exhaust baffle having a substantially inverted C-shaped cross section is inserted along the inner wall of the vacuum chamber, the vacuum chamber is not increased in size. Further, a vacuum exhaust path having a substantially triangular cross section can be formed at low cost without providing a complicated mechanism, and a plasma processing apparatus having stable discharge characteristics can be obtained. Furthermore, in the plasma processing apparatus of claim 3,
The gas flow can be isotropically guided into the evacuation path, and the distribution of the film thickness to be formed can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a P-CVD apparatus showing one embodiment of the present invention.

FIG. 2 is a partially enlarged perspective view showing a configuration example of an exhaust baffle plate.

FIG. 3 is a schematic sectional view showing an application example of the present invention to a reactive ion etching apparatus.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Shower electrode 3 Lower electrode 4 Exhaust baffle plate 5 Vacuum exhaust path 6 Gas exhaust port

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/31 H01L 21/302 C

Claims (3)

[Claims] In a vacuum chamber capable of maintaining a vacuum state,
Parallel plate type high frequency electrode for generating plasma,
In a plasma processing apparatus having a process gas outlet and a gas exhaust port connected to a vacuum exhaust facility, a cross-sectional shape of an exhaust path provided in a vacuum chamber connected to the exhaust port is substantially triangular. Plasma processing equipment. 2. The plasma processing apparatus according to claim 1, wherein an exhaust baffle plate having a substantially inverted C shape is formed along the inner wall of the vacuum chamber, and a cross-sectional shape of the exhaust path is made substantially triangular. . 3. The plasma processing apparatus according to claim 2, wherein the exhaust baffle is provided with a slit-shaped vacuum exhaust hole substantially over the entire circumference of the chamber.