JPH06318552A - Plasma processing and its apparatus - Google Patents

Abstract

PURPOSE:To provide a method of processing plasma and an apparatus which can process plasma while controlling the generation of particles which cause various problems. CONSTITUTION:A plasma processing gas is introduced into a vacuum vessel 1 and the gas is made into plasma by impressing discharge electric power under the preset vacuum condition. In a plasma processing method and its apparatus for performing an intended processing on the surface of a substrate S1 to be processed under plasma, electric power to be turned on at the starting time of impressing discharge electric power is set as the discharge electric power lower than that required for performing the intended processing. After the low discharge electric power is impressed for a fixed period of time, it is gradually converted to impressing the required discharge electric power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for producing a film on a substrate, obtaining a wiring pattern, etc. when manufacturing a device using a semiconductor such as a thin film transistor and various sensors using a semiconductor, a solar cell and the like. Plasma CV for etching the formed film according to a predetermined pattern
D, a plasma processing method such as plasma etching, and an apparatus for performing the same.

[0002]

2. Description of the Related Art Various types of plasma CVD apparatus are known. As a typical example thereof, a parallel plate type plasma CVD apparatus shown in FIG. 6 will be described. This apparatus has a vacuum container 1 in which an electrode 2 also serving as a substrate holder for setting a film formation substrate S1 and this electrode are provided. Is provided with an electrode 3 facing to.

The electrode 2 is usually a ground electrode, and
A heater 21 for heating the substrate S1 placed thereon to a film forming temperature is additionally provided. The heater 21 is separated from the electrode 2 when the substrate S1 is heated by radiant heat. The electrode 3 is a power application electrode for applying high-frequency power or direct-current power to the film-forming gas introduced between the electrode 3 and plasma, and in the illustrated example, a high-frequency power source 32 via a matching box 31. Are connected.

In the illustrated example, the electrode 3 has a porous electrode plate 33 in the opening of a gas nozzle 34 which constitutes a part of the electrode.
The electrode plate 33 is provided with a large number of gas supply holes each having a diameter of about 0.5 mm so that the gas supplied from the gas nozzle 34 is entirely discharged from each hole between both electrodes. I am doing it. Such a configuration is suitable for forming a film on a large area substrate.

An exhaust pump 52 is connected to the vacuum container 1 through an opening / closing valve 51, and a gas supply unit 4 is connected to the gas nozzle 34.
The gas supply unit 4 includes one or more mass flow controllers 421, 422, ... And open / close valves 431, 432.
The gas sources 441, 442, ... Supplying a predetermined amount of film forming gas via.

According to this parallel plate type plasma CVD apparatus, the film formation target substrate S1 is placed on the electrode 2 in the vacuum container 1, and the inside of the container 1 is formed at a predetermined temperature by opening the valve 51 and operating the exhaust pump 52. The film vacuum is maintained, and the film forming gas is introduced from the gas supply unit 4 through the nozzle 34 and the gas supply holes of the electrode plate 33. A high-frequency voltage is applied to the high-frequency electrode 3 from the power source 32, and the gas introduced thereby is turned into plasma, and a desired film is formed on the surface of the substrate S1 under this plasma.

Various types of plasma etching apparatuses are also known. As a representative example, a parallel plate type etching apparatus shown in FIG. 7 will be described. This apparatus also includes a vacuum container 10, in which an electrode 20 also serving as a substrate holder for setting a substrate S2 on which an etching target film is formed and an electrode 20 and The electrode 30 is provided so as to face the electrode 20.

The electrode 20 is used as a power application electrode for applying high frequency power or direct current power to the etching gas introduced between the electrode 20 and the electrode to generate plasma, and in the illustrated example, a matching box 201 is used. Connected to the high frequency power source 202. The electrode 30 is a ground electrode, and a porous electrode plate 302 is provided at the opening of a gas nozzle 301 that constitutes a part of the electrode. The electrode plate 302 has a large number of gas supply holes with a diameter of about 0.5 mm. Thus, the gas supplied from the gas nozzle 301 is wholly discharged from the hole between the electrodes.

An exhaust pump 72 is connected to the vacuum container 10 via an opening / closing valve 71, and a gas supply unit 6 is connected to the gas nozzle 301. The gas supply unit 6 includes one or more mass flow controllers 621, 622, ... And on-off valves 631, 6
The gas sources 641, 642, ... Supplying a required amount of etching gas via 32.

According to this etching apparatus, the substrate S2 to be etched is placed on the high frequency electrode 20 in the container 10, and the inside of the container 10 is maintained at a predetermined etching vacuum degree by opening the valve 71 and operating the exhaust pump 72. , Gas supply unit 6
Etching gas from the nozzle 301 and the electrode plate 302
Is introduced through the gas supply hole of Further, a high-frequency voltage is applied to the electrode 20 from a high-frequency power source 202, the gas introduced thereby is turned into plasma, and the film on the substrate S2 is etched under this plasma. The electrode 20
May be cooled by the water cooling device 200 or the like, if necessary.

In such a conventional plasma processing method and apparatus, the electric power required for plasma generation is immediately supplied to the discharge space. FIG. 8 is a graph showing an example of such power application, in which a line 81 on the graph shows the power supplied at the start of discharge, and a line 82 shows the power supplied to the plasma in the discharge space. The electric power input at the start of discharge is not efficiently supplied to the plasma due to the reflected electric power. Therefore, matching adjustment is performed by the matching box 31 (or 201) to efficiently apply electric power to the plasma.

[0012]

However, in such conventional plasma CVD, particles generated by a gas phase reaction in plasma adhere to the film formed on the surface of the substrate or are mixed in the film. There is a problem that the film quality is deteriorated, and the generated particles adhere to various parts inside the vacuum container and contaminate it. The particles adhering to the respective parts in the vacuum container may be peeled off and adhere to the substrate to be processed, so that they have to be removed and cleaned, which is troublesome.

Also in the plasma etching, there is a problem that particles are similarly formed by the gas phase reaction and adhere to the surface to be etched or to each part in the vacuum container. For example, when a wiring pattern is formed by etching, such particles may deteriorate the accuracy of patterning, and may cause disconnection in forming a fine line.

Therefore, according to the present invention, a plasma processing gas is introduced into a vacuum container, and the gas is turned into plasma by applying discharge power under a predetermined vacuum state. It is an object of the present invention to provide a plasma processing method and apparatus for performing plasma processing, which is capable of performing plasma processing while suppressing generation of particles that cause various problems.

[0015]

Means for Solving the Problems The inventors of the present invention have conducted extensive research to solve the above-mentioned problems. As a result, when a high voltage is applied to generate plasma, most of the power is consumed for particle generation. It was found that a large amount of particles are generated and grow at the start of discharge, and that a large amount of these particles are generated as the applied voltage at the start of discharge is large and the reflected power is large.

The present invention is based on this research, and in order to solve the above-mentioned problems, a plasma processing gas is introduced into a vacuum container, and the gas is turned into plasma by applying discharge power under a predetermined vacuum state. In a plasma processing method of performing an intended treatment on a surface of a substrate to be treated under plasma, the electric power applied at the start of applying the electric discharge power is set to a discharge power lower than a discharge electric power required for the intended treatment, It is intended to provide a plasma processing method characterized in that after the discharge power is applied for a certain period of time, the required discharge power application is gradually switched.

As a method for switching the applied power, there may be considered a method in which after the initial application of the low discharge power, the discharge power required for the low power application is gradually and continuously switched. Further, when gradually changing the discharge power application to the required discharge power application, after the first low discharge power application, the power application is stopped for a certain period of time, and then the discharge power application is restarted to change the power to the above It is possible to gradually switch to the required discharge power.

Further, in order to further suppress the generation of particles, it may be considered to apply pulse modulation to the applied electric power at the beginning and after that. In any case, it is desirable to maintain the power input rate so that the matching does not largely shift when the applied power increases. This is because, according to the research by the present inventor, particles are likely to be generated even when the applied voltage changes at the time of adjusting the deviation of matching.

Further, in the plasma processing apparatus of the present invention for solving the above-mentioned problems, a plasma processing gas is introduced into a vacuum container, and the gas is turned into plasma by applying discharge power by a power applying means under a predetermined vacuum state, A plasma processing apparatus for performing a target process on a surface of a substrate to be processed under the plasma, wherein the power applying means starts applying power with a discharge power lower than a discharge power required for the target process. However, it is characterized in that it further comprises means for gradually switching to the required discharge power, and means for controlling the input timing of each applied power switched by the switching means.

Also in this apparatus, the power applying means may include means for applying pulse modulation to the applied power.

[0021]

According to the plasma processing method and apparatus of the present invention,
The discharge power applied to the discharge space is lower than the discharge power required for the target process at the start of power application, and after the low discharge power is applied for a certain period of time, the discharge power is gradually applied. And the particles generated by the gas phase reaction in the plasma are reduced by this power application pattern.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. As a typical example thereof, a parallel plate type plasma CVD apparatus shown in FIG. 1 and a film forming method by the apparatus will be described. The plasma CVD apparatus is provided with an RF amplifier 35 and a function generator (arbitrary waveform generator) 36 in place of the conventional high frequency power source 32 shown in FIG.
These are connected to the matching box 31. The waveform formed by the arbitrary waveform generator 36 is amplified by the amplifier 35 and supplied to the electrode 3 via the matching box 31. ON, OFF and ON time of high frequency power application,
The arbitrary waveform generator 36 can set and control the off-time and control the magnitude of the applied power.

The other structure is the same as that of the conventional device shown in FIG. According to this parallel plate type plasma CVD apparatus, the film formation target substrate S1 is installed on the susceptor 22 of the electrode 2 in the vacuum container 1, and the inside of the container 1 is the opening of the valve 51 and the exhaust pump 5.
The predetermined film forming vacuum degree is maintained by the operation 2 and the gas supply unit 4
The film-forming gas is introduced from the nozzle 34 through the gas supply holes of the electrode plate 33. Further, the waveform formed by the function generator 36 is amplified and applied to the high-frequency electrode 3 by the amplifier 35, and the gas introduced thereby is turned into plasma, and a desired film is formed on the surface of the substrate S1 under this plasma. .

However, in this embodiment, when applying high-frequency power to the electrode 3, initially, in other words, at the start of power application, first, desirably, the minimum discharge start voltage required for plasma generation is applied, and then, The discharge power required for film formation is gradually increased. This makes it possible to avoid a situation in which a large amount of power is spent for particle generation and growth and a large amount of particles are generated if the discharge power required for film formation is applied from the beginning.

Power application patterns are shown in FIGS.
The patterns shown in the respective figures can be exemplified. In any case,
Matching does not change significantly when the applied power increases,
Moreover, it is assumed that the stability of plasma is not significantly impaired, and also in this respect, the generation of particles is suppressed. According to the power application pattern shown in FIG. 2, after the first discharge start low power application, the discharge power is gradually switched to the required discharge power in succession to the low power application.

In the pattern shown in FIG. 3, after the application of the low power for starting the discharge, the application of the power is stopped for a certain period of time, and then the application of the discharge power is restarted to gradually switch the power to the required discharge power. This is because the property of the discharge space is changed by the first discharge, and the change of the dielectric constant in the discharge space caused when the next electric power is applied is alleviated to reduce the matching deviation. . With this pattern, the generation of particles can be further suppressed as compared with the case of the pattern of FIG.

Further, in the patterns of FIGS. 4 and 5, FIG.
In addition, in the pattern of FIG. 3 and FIG. 3, pulse modulation is applied to each of the input powers at the beginning and after that, whereby particle generation can be further reduced. This is because the number of particles floating in the discharge space and the floating time are reduced by applying pulse modulation. The pulse modulation in the power application patterns of FIGS. 4 and 5 can be set by the function generator 36. In this example, a high frequency of 13.56 MHz is set to 10 to 1K.
Pulse-like modulation (in other words, amplitude modulation) is performed in the range of Hz, and high-frequency power application is turned on and off in that range.
4B schematically shows an example of pulse modulation of the part a of the power application pattern in FIG. 4A, and FIG.
The figure schematically shows an example of pulse modulation of the part b of the power application pattern in the same figure (A). In the patterns of FIG. 3 to FIG. 5, the timing of each power application and the magnitude of each power application are controlled by the function generator 36.

In each of the power application patterns, the applied power is increased stepwise, but it is also possible that the power is changed steplessly or by a combination of stepless and stepwise. Next, a specific example in which the SiNx film is formed by the parallel plate type plasma CVD apparatus shown in FIG. 1 will be described. The number of particles described last in each example is the number of particles of 0.5 μm or more. Example 1: Step power application <Deposition conditions> ・ Deposition vacuum degree 0.8 Torr ・ Substrate temperature 250 ° C ・ Gas used SiH ₄ 50 sccm, NH ₃
200sccm ・ Electrode size 300 × 300mm □ ・ Used substrates 4 inch 4 silicon substrates side by side ・ Deposition time 3 minutes ・ Voltage application method (according to the pattern of FIG. 2) ・ Power waveform CW (cycle wave 13.56MHz) ・ Hourly The applied power is shown below.

Time (seconds) Power 0 (start of film formation) to 250 W (discharge start power) 2 to 4 100 W 4 to 6 150 W 6 to 180 (end of film formation) 200 W (power necessary for film formation) Substrate 1 Number of particles on the plate: 1 or less before film formation, about 40 after film formation Example 2: Step power application + pulse power <film formation conditions> -Deposition vacuum degree 0.8 Torr-Substrate temperature 250 ° C-Gas used SiH ₄ 50 sccm, NH ₃
200sccm ・ Electrode size 300 × 300mm □ ・ Used substrates 4 inch 4 silicon substrates side by side ・ Deposition time 3 minutes ・ Voltage application method (according to the pattern of FIG. 4) ・ Power waveform pulse (50 at 13.56 MHz high frequency)
0 Hz amplitude modulation, 1 msec on, 1 msec off repeated, duty 50%)-Applied power for each time is shown below.

Time (second) Power 0 (start of film formation) to 250 W (power to start discharge) 2 to 4 100 W 4 to 6 150 W 6 to 180 (end of film formation) 200 W (power necessary for film formation) Substrate 1 Number of particles on a sheet: 1 or less before film formation, about 20 after film formation Example 3: Step power application + optional off time <film formation conditions> -Deposition vacuum degree 0.8 Torr-Substrate temperature 250 ° C-Gas used SiH ₄ 50sccm, NH ₃
200 sccm ・ Electrode size 300 × 300 mm □ ・ Used substrates 4 inch 4 silicon substrates side by side ・ Deposition time 3 minutes ・ Voltage application method (according to the pattern of FIG. 3) ・ Power waveform CW (13.56 MHz) ・ Electric power applied every hour Is shown below.

Time (seconds) Power 0 (start of film formation) to 250 W (power to start discharge) 2 to 3 OFF 3 to 5 50 W 5 to 7 100 W 7 to 9 150 W 9 to 180 (finish of film formation) 200 W (film formation) (Power required for) ・ Number of particles on one substrate: 1 or less before film formation, about 8 after film formation Example 4: Step power application + pulse power + arbitrary off time <film formation conditions> ・ Deposition vacuum degree 0 .8 Torr ・ Substrate temperature 250 ℃ ・ Working gas SiH ₄ 50 sccm, NH ₃
200sccm ・ Electrode size 300 × 300mm □ ・ Used substrates 4 inch 4 silicon substrates side by side ・ Deposition time 3 minutes ・ Voltage application method (according to the pattern of FIG. 5) ・ Power waveform pulse (500Hz amplitude modulation, duty 5)
0%) ・ Applied power for each time is shown below.

Time (sec) Power 0 (start of film formation) to 250 W (discharge start power) 2 to 3 OFF 3 to 5 50 W 5 to 7 100 W 7 to 9 150 W 9 to 180 (finish of film formation) 200 W (film formation) Number of particles on one substrate: 1 or less before film formation, about 6 after film formation With the above specific example, discharge power of 200 W was continuously applied for 3 minutes from the beginning, and other conditions were Similar to Examples 1 to 4,
A SiNx film was also formed, but the number of particles in this case was 1 or less before film formation and 200 after film formation.

As can be seen from the above specific examples, when the low discharge power is applied and then the discharge power is gradually changed to the required discharge power, the substrate on which the film is formed is compared with the conventional example. The number of particles was reduced to about 1/5. Furthermore, when the power application is stopped for a certain period of time after the first low discharge power is applied, or when pulse modulation is applied to the initial and subsequent input powers, the number of particles is about 1/10 to 1 as compared with the conventional example. It was reduced to / 40.

Although the plasma CVD method and apparatus have been described above, the present invention can also be applied to the plasma etching method and apparatus.

[0035]

As described above, according to the present invention,
A plasma processing method and apparatus in which a plasma processing gas is introduced into a vacuum container, the gas is turned into plasma by applying discharge power under a predetermined vacuum state, and a target processing is performed on a surface of a substrate to be processed under the plasma. Therefore, while suppressing the generation of particles that cause various problems,
A plasma processing method and apparatus capable of performing plasma processing can be provided. Further, in the plasma processing method and apparatus, when the discharge start low power is applied, the power supply is stopped for a certain period of time, and then the discharge power is started again to gradually switch the power to the required discharge power, particles are not generated. It can be further suppressed.

Further, in the above plasma processing method and apparatus, when pulse modulation is applied to each input power at the beginning and thereafter, generation of particles can be suppressed to that extent.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a plasma CVD apparatus that is an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a discharge power application pattern according to the present invention.

FIG. 3 is a diagram showing another example of a discharge power application pattern according to the present invention.

FIG. 4 is a diagram showing still another example of a discharge power application pattern according to the present invention.

FIG. 5 is a diagram showing still another example of a discharge power application pattern according to the present invention.

FIG. 6 is a diagram showing a schematic configuration of an example of a conventional plasma CVD apparatus.

FIG. 7 is a diagram showing a schematic configuration of an example of a conventional plasma etching apparatus.

FIG. 8 is a diagram showing a conventional discharge power application pattern.

[Explanation of symbols]

 1, 10 Vacuum container 2, 30 Ground electrode 20, 3 High frequency electrode 201, 31 Matching box 202, 32 High frequency power source 21 Heater 51, 71 Open / close valve 52, 72 Exhaust pump 4, 6 Gas supply unit S1 Film formation target substrate S2 Etching Target board 35 RF amplifier 36 Function generator (arbitrary waveform generator)

Claims (6)

[Claims] 1. A plasma for introducing a plasma processing gas into a vacuum container, converting the gas into plasma by applying discharge power under a predetermined vacuum state, and subjecting the surface of the substrate to be processed to the intended treatment under the plasma. In the processing method, the power input at the start of the application of the discharge power is a discharge power lower than the discharge power required for the target process, and the low discharge power is applied for a certain period of time, and then the required discharge power is gradually increased. A plasma processing method characterized by switching to application. 2. In gradually switching the application of the discharge power to the application of the required discharge power, after the first application of the low discharge power, the application of the low power is gradually switched to the required discharge power continuously. The plasma processing method according to claim 1. 3. When the discharge power application is gradually switched to the required discharge power application, after the first low discharge power application, the power application is stopped for a certain period of time, and then the discharge power application is started again. The plasma processing method according to claim 1, wherein electric power is gradually switched to the required discharge electric power. 4. The plasma processing method according to claim 1, wherein pulse modulation is applied to the applied power at the beginning and after that. 5. A plasma processing gas is introduced into a vacuum container, and the gas is turned into plasma by applying discharge power by a power applying means under a predetermined vacuum state, and the target gas is applied to the surface of a substrate to be processed under the plasma. In the plasma processing apparatus for performing processing, the power applying means starts power application with discharge power lower than the discharge power required for the target processing, and then gradually switches to the required discharge power. And a means for controlling the input timing of each applied power switched by the switching means. 6. The plasma processing apparatus according to claim 5, wherein the power applying means includes means for applying pulse modulation to the applied power.