JP2004095704A - Microwave plasma treatment method and apparatus thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a substrate treatment speed from fluctuating by the decrease of the temperature of a dielectric plate (e.g., quartz plate), to improve the operation rate of an apparatus and to improve the throughput. <P>SOLUTION: In the microwave plasma treatment method of applying a plasma treatment to a substrate (28) which is held on a vertically movable substrate holding stand (26) with a heater by guiding a plasma gas generated by a microwave supplied to an upper portion within a vacuum container (10) via a dielectric plate (16) to the substrate (28), before the treatment of the substrate (28), the substrate holding stand (26) is made proximate to the dielectric plate (16), and the dielectric plate (16) is heated by the substrate holding stand (26). The substrate holding stand (26) with the heater may be moved up while the substrate (28) is not held but may be also moved up while holding the substrate (28) to heat the dielectric plate (16). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a plasma processing apparatus for performing a process such as ashing on a substrate or the like using plasma.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a method of performing an ashing (ashing) process, an etching process, a thin film forming process, and the like on a substrate (a wafer or the like) using plasma generated in a vacuum vessel has been widely known.
[0003]
In ashing, the reaction gas is turned into plasma in a plasma generation chamber, and the resist on the substrate surface is reacted with ions and radicals activated by the plasma to form a gas, which is then exhausted to remove the resist. In etching, a high frequency voltage for discharge is applied to a holding table of a substrate (wafer) to be processed to cause ions or radicals to collide with the substrate surface (sputter) or to chemically react with the substrate surface to perform etching (dry). etching).
[0004]
In the thin film formation process, for example, a reaction gas is turned into plasma to convert it into chemically active ions or radicals (excited atoms and molecules), and these particles promote a chemical reaction on the substrate surface, thereby depositing products on the substrate surface. (Such as plasma CVD).
[0005]
There is a processing apparatus using this type of plasma that uses microwaves to generate plasma in a plasma generation chamber. For example, there are a microwave plasma source and an electron cyclotron resonance (ECR) plasma source.
[0006]
As described above, in a plasma source that guides microwaves into a vacuum vessel through a quartz plate, a waveguide that guides the microwaves to the quartz plate is provided with a long window in a longitudinal direction of the waveguide, and the microwaves are introduced into the vacuum vessel through the windows. To improve efficiency (referred to as a slot antenna system).
[0007]
[Problems to be solved by the invention]
In such a microwave source, the temperature of the quartz plate greatly affects the generation of plasma. That is, when the temperature of the quartz plate is low, for example, when it is cooled to about room temperature, the activity of radicals generated by plasma conversion is significantly lost (referred to as deactivation).
[0008]
Therefore, the processing speed of the substrate decreases. Conversely, when the temperature of the quartz plate increases due to the continuation of the plasma processing, the processing speed increases. When the temperature change of the quartz plate is large, the fluctuation of the plasma processing speed becomes large, and the quality of the processed product becomes unstable. For example, in an ashing processing apparatus, an ashing rate (A / R) indicating an amount removed in a unit time becomes unstable.
[0009]
Therefore, conventionally, prior to performing the plasma processing on the substrate, plasma discharge is performed for a certain period of time to increase the temperature of the quartz plate. The discharge performed for such a purpose is herein referred to as idle discharge.
[0010]
On the other hand, in this type of apparatus, a large number of substrates are loaded in a cassette, and the cassette is accommodated in a cassette accommodation room connected to a vacuum container. Then, the substrates are carried into and out of the vacuum container one by one from the cassette, and when all the substrates (one lot) have been processed, the cassette is replaced to continue the processing. Collectively processing the cassettes in this manner is referred to as lot processing here.
[0011]
In this case, the idle discharge is performed every time the cassette is replaced. That is, since the quartz plate cools during cassette exchange (during standby or idling), an empty discharge is performed each time processing of a substrate in a new cassette is started.
[0012]
However, when the empty discharge is performed each time the cassette is replaced, the processing of the substrate cannot be started until the empty discharge is completed, and the operation rate of the apparatus is reduced. In other words, there is a problem that the number of processed sheets (throughput) per unit time is reduced.
[0013]
The present invention has been made in view of such circumstances, and can prevent a fluctuation in a substrate processing speed due to a decrease in the temperature of a dielectric plate (eg, a quartz plate), increase the operation rate of the apparatus, and increase the throughput. A first object is to provide a microwave plasma processing method. It is a second object of the present invention to provide a microwave plasma processing apparatus used directly for carrying out this method.
[0014]
Configuration of the Invention
According to the present invention, a first object is to guide a plasma gas generated by microwaves supplied through a dielectric plate to an upper portion in a vacuum vessel to a substrate held on a vertically movable substrate holder with a heater. In the microwave plasma processing method for performing plasma processing on the substrate, prior to the processing of the substrate, the substrate holding table is brought close to the dielectric plate, and the dielectric plate is heated by the substrate holding table. Microwave plasma processing method.
[0015]
In this case, the substrate holder with heater may be raised when the substrate is not held, or may be raised while holding the substrate to heat the dielectric plate. For example, when a large number of substrates are loaded in a cassette and continuous processing is performed for each cassette, the holding plate may be raised during the waiting time (idle time) during cassette replacement to heat the dielectric plate.
[0016]
The present invention also encompasses those used in combination with idle discharge. For example, it includes a method in which the dielectric is preheated by raising the holding table, and then an empty discharge is performed. In this case, the desired effect can be obtained because the time of the idle discharge can be shortened.
[0017]
The same object is achieved in a microwave plasma processing method in which a plasma gas generated by microwaves supplied through a dielectric plate to an upper portion in a vacuum vessel is guided to a substrate held on a vertically movable substrate holding table to perform substrate plasma processing. A microwave plasma processing method comprising an electric heater mounted near the dielectric plate and heating the dielectric plate by the heater prior to the plasma processing of the substrate. is there.
[0018]
According to the present invention, a second object is to guide a plasma gas generated by microwaves supplied through a dielectric plate to an upper portion inside a vacuum vessel to a substrate held on a vertically movable substrate holding table with a heater. In a microwave plasma processing apparatus for performing plasma processing, a vacuum vessel having a plasma generation unit and a reaction chamber continuous below the plasma generation unit, a gas flow control valve for controlling a flow rate of a reaction gas supplied to the plasma generation unit, and the reaction chamber An exhaust pump that exhausts air from the vacuum vessel to depressurize the inside of the vacuum vessel, a substrate holder with a heater that moves up and down in the vacuum vessel and can be made close to the dielectric plate as necessary, and a reaction gas in the vacuum vessel. While supplying the gas, the inside of the vacuum vessel is evacuated, and the reaction gas is plasma-discharged while maintaining a predetermined gas atmosphere to process the substrate, while holding the substrate when the substrate is not processed. Microwave plasma processing apparatus, wherein a is raised comprises a controller for heating a dielectric plate in the substrate holder, and is achievable by.
[0019]
Usually, a quartz plate is preferably used as the dielectric plate. When a plurality of substrates are loaded in a cassette, and the cassette is accommodated in a cassette accommodating chamber and the substrates included in one cassette are continuously processed as one lot (lot processing), the substrate is held during cassette replacement. It is preferable to raise the stage to heat the dielectric plate. This is because idle time (standby time, idle time) during cassette replacement can be effectively used.
[0020]
The same object is achieved in a microwave plasma processing apparatus that performs plasma processing on a substrate by guiding a plasma gas generated by microwaves supplied through a dielectric plate to an upper portion in a vacuum vessel to a substrate held on a vertically movable substrate holding table. The present invention can also be achieved by a microwave plasma processing apparatus including an electric heater for heating the dielectric plate.
[0021]
Embodiment
FIG. 1 is a diagram showing a basic configuration of a microwave plasma etching apparatus according to an embodiment of the present invention, and FIG. 2 is a view showing a state when the quartz plate is heated.
[0022]
In FIGS. 1 and 2, reference numeral 10 denotes a vacuum vessel, in which an upper part is a cylindrical plasma generating part 12 and a lower part is a cylindrical reaction chamber 14. A quartz plate 16, which is a dielectric, is fitted on the upper wall of the plasma generating unit 12, and a microwave 20 is guided from a microwave oscillator 22 by a waveguide 18 on the upper surface of the quartz plate 16.
[0023]
The plasma generating section 12 has a smaller diameter than the reaction chamber 14, and the wall area is reduced to reduce the influence of the state of the wall surface on the reaction. A reaction gas such as O ₂ gas can be supplied to the plasma generation unit 12 from the reaction gas introduction hole 24. A substrate holder 26 with a heater is provided in the reaction chamber 14 so as to be able to move up and down, and a substrate 28 which is an object to be subjected to plasma processing, for example, ashing, is held on the holder 26.
[0024]
The substrate 28 is a circular silicon wafer, and the substrate 28 is held at the center of the substrate holder 26. The substrate 28 has a smaller diameter than the substrate holder 26, and the entire surface of the substrate holder 26 is covered by a quartz mask ring 30 surrounding the substrate 28 and its outer periphery, and the substrate holder 26 is protected from plasma. . The substrate 28 and the mask ring 30 are held on the holding table 26 by an electrostatic chuck (not shown).
[0025]
A horizontal annular straightening plate 32 is fixed to the inner surface of the reaction chamber 14, and an exhaust hole 34 is opened below the straightening plate 32. A number of small holes 36 are formed in the flow straightening plate 32 at equal intervals in the circumferential direction to stabilize the flow of the reaction gas in the reaction chamber 14.
[0026]
Next, the operation of this embodiment will be described using an ashing process as an example. The substrate 28 to be processed to which the etching resist is attached is carried into the vacuum vessel 10 by a loading device (not shown), and is held on the holding table 26. A reaction gas such as O ₂ gas is supplied from the reaction gas supply hole 24 while the substrate 28 is kept at a constant temperature on the holding table 26.
[0027]
On the other hand, the interior of the vacuum vessel 10 is depressurized by exhausting air from the exhaust port 34. In this state, the microwave oscillator 22 is activated to guide the microwave to the plasma generator 12. The oscillation frequency of the microwave is selected according to the type of the reaction gas. In the case of O ₂ gas to 2.45 GHz _Z.
[0028]
In this case, the reaction gas (O ₂ ) is converted into plasma, and active oxygen radicals (O ^* ) generated by the plasma are reacted with the resist which is an organic film. This reaction turns the resist into CO ₂ , CO, H ₂ O, etc., and is exhausted from the exhaust hole 34.
[0029]
In order to heat the quartz plate 16, as shown in FIG. 2, the substrate holder 26 is raised and brought close to the quartz plate 16. The substrate holder 26 is heated by a built-in heater (not shown). In the case of the ashing process, the upper surface of the holding table 26 is usually heated to about 250 ° C. By bringing the substrate holder 26 close to the quartz plate 16 in this manner, the quartz plate 16 can be heated mainly by radiant heat in the vacuum vessel 10 under reduced pressure.
[0030]
It is desirable to maintain the inside of the vacuum vessel 10 in a reduced pressure state. When the quartz plate 16 is heated by the holding table 26, the degree of vacuum of the vacuum vessel 10 may be reduced (the internal pressure is increased to approach the atmospheric pressure). After the quartz plate 16 is heated by the substrate holder 26, the empty discharge may be further performed. However, since the quartz plate 16 is preheated, the time of the empty discharge can be reduced.
[0031]
[Other embodiments]
In the embodiment shown in FIGS. 1 and 2, the quartz plate 16 is heated by raising the substrate holding table 26 with a heater so as to approach the quartz plate 16. In the present invention, the intended object can be achieved by providing a heater for heating the quartz plate, for example, an electric heater.
[0032]
For example, an electric heater 40 is attached to the outer periphery of the quartz plate 16 as shown by a virtual line in FIG. The quartz plate 16 may be heated by causing the heater 40 to generate heat when necessary. For example, the quartz plate 16 is heated by the heater 40 only when the supply of the microwave 20 is stopped and the plasma generation is interrupted.
[0033]
Instead of the heater 40, a heater (not shown) closely attached to the surface of the quartz plate 16 may be used. For example, a flat heater may be attached to a surface other than the long window (slot) provided in the waveguide 18. The quartz plate 16 may be further heated by the heater 40 by air discharge.
[0034]
[Other embodiments]
3 is a system diagram showing a control system of the plasma etching apparatus, FIG. 4 is a diagram showing a state where the plasma etching apparatus is combined with a cassette accommodating chamber, and FIG. 5 is an operation flowchart thereof. 3 and 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.
[0035]
In FIG. 3, reference numeral 50 denotes an elevator for elevating the holding table 26. Oxygen gas (O ₂ ) as a reaction gas is supplied from a supply source 52 through a flow control valve 54 to a reaction gas introduction hole 24 provided on a wall surface of the plasma generation unit 12.
[0036]
A dry pump 56 is connected to the exhaust hole 34 provided in the lower part of the reaction chamber 14. The pressure in the vacuum vessel 10 is detected by a vacuum gauge (VG, Vacuum Gauge) 58.
[0037]
Reference numeral 60 denotes a controller, which includes a CPU 62 and various interfaces. The controller 60 controls the ashing process of the substrate 28 (see FIG. 1) as described above. For example, the substrate 28 is ashed by the operation shown in FIG.
[0038]
A cassette housing chamber 64 is connected to the vacuum container 10 as shown in FIG. A gate valve 66 is provided on a partition wall between the vacuum container 10 and the cassette housing chamber 64. Another gate valve 68 is opened in the cassette accommodating chamber 64, and the cassette 70 is taken in and out of the gate accommodating chamber 64. A large number of substrates 28 are loaded in the cassette 70.
[0039]
The unprocessed substrate 28 is transported from the cassette 70 to the substrate holder 26 by a loading device (not shown) by opening the gate valve 66, and the processed substrate 28 is returned from the substrate holder 26 to the cassette 70. . When all the substrates 28 in the cassette 70, that is, one lot of the substrates 28 are processed, the gate valve 68 is opened to unload the cassette 70 and replace it with the cassette 70 loaded with the unprocessed substrate 28.
[0040]
Next, the operation of this device will be described with reference to FIG. The cassette 70 loaded with the unprocessed substrate 28 is carried into the cassette storage chamber 64, and the pressure in the cassette storage chamber 64 is reduced. While the cassette 70 is being loaded, the controller 60 raises the substrate holding table 26 while generating heat so as to approach the quartz plate 16 to bring it into the state shown in FIG. In this state, the quartz plate 16 is heated (FIG. 5, step S100).
[0041]
The controller 60 lowers the substrate holder 26 (Step S102), opens the gate valve 66, and carries the unprocessed substrate 28 from the cassette 70 onto the substrate holder 26 (Step S104). After closing the gate valve 66, the reaction gas is supplied while the pressure inside the vacuum vessel 10 is reduced, and the microwave oscillator 22 is operated to generate plasma. The plasma processing (ashing processing) is performed on the substrate 28 by the plasma gas (Step S106).
[0042]
The processed substrate 28 is returned to the cassette 70 through the opened gate valve 66 (step S108). The operations in steps S102 to S108 are repeated to process all the substrates 28 in the cassette 70. That is, processing for one lot is continuously performed (step S110).
[0043]
If the processing for one lot is completed and there is another unprocessed cassette 70 (step S112), the cassette 70 is replaced (step S116). Prior to or concurrently with the replacement of the cassette 70, the substrate holding table 26 is raised to be brought close to the quartz plate 16 (step S114). Since the substrate holding table 26 is heated by the heater, The quartz plate 16 is also heated by the radiant heat. After the replacement of the cassette 70, the substrate holding table 26 is lowered (step S102), and the above operation is repeated.
[0044]
After the quartz plate 16 is heated by the substrate holding table 26, the quartz plate 16 may be further heated by performing an empty discharge and then the plasma treatment of the substrate 28 may be performed. In this case, the time of the empty discharge can be remarkably reduced as compared with the conventional method of heating the quartz plate 16 only by the empty discharge.
[0045]
In the above embodiment, the quartz plate 16 is heated by the substrate holder 26. When the electric heater 40 (see FIGS. 1 and 3) is provided on the quartz plate 16, the controller 60 Is generated to heat the quartz plate 16.
[0046]
【The invention's effect】
According to the first aspect of the present invention, as described above, the dielectric plate can be heated using the heater of the substrate holding table, and the dielectric plate is heated in advance before the substrate is subjected to the plasma processing. Processing speed is stabilized, and the operation rate and throughput of the apparatus are increased.
[0047]
In the case where a plurality of substrates are loaded in a cassette and one cassette is continuously processed as one lot, the dielectric plate can be heated by the substrate holding table during the cassette exchange, and the waiting time of the apparatus is reduced. Utilization can further improve the operation rate of the device (claim 2). After the dielectric plate is heated by the substrate holding table, the dielectric plate may be further heated using air discharge. In this case, since the heating of the dielectric plate is performed more reliably, the plasma processing speed can be further stabilized.
[0048]
According to the fourth aspect of the invention, since the electric heater for heating the quartz plate is provided, the same effect as the first aspect of the invention can be obtained. According to the invention of claims 5 to 8, there is provided an apparatus directly used for carrying out the method of claims 1 to 3. According to the ninth aspect of the present invention, there is provided an apparatus directly used for implementing the fourth aspect of the present invention.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of an apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a heating state of a quartz plate. FIG. 3 is a control system diagram. FIG. 4 is a diagram showing a coupling state with a cassette accommodating chamber. 5 Explanation of operation [Description of reference numerals]
DESCRIPTION OF SYMBOLS 10 Vacuum container 12 Plasma generation part 16 Reaction chamber 18 Waveguide 20 Microwave 22 Microwave generator 26 Substrate holding base 28 Substrate 40 Heater 50 Elevator 60 Controller 64 Cassette accommodation room 70 Cassette

Claims (9)

In a microwave plasma processing method for performing plasma processing on a substrate by guiding a plasma gas generated by microwaves supplied through a dielectric plate to an upper portion in a vacuum vessel to a substrate held on a vertically movable substrate holding table with a heater, A microwave plasma processing method, wherein prior to the processing of the substrate, the substrate holder is brought close to the dielectric plate, and the dielectric plate is heated by the substrate holder. The method of claim 1, wherein
a) one substrate is loaded into a vacuum container from a cassette containing a plurality of substrates, and is held on a substrate holding table;
b) plasma treating the substrate;
c) unloading the substrate from the vacuum vessel;
d) repeating the steps a) to c) to process all the substrates stored in the cassette;
e) raising the substrate holder and heating the dielectric plate in proximity to the dielectric plate;
f) replace cassettes and repeat steps a) -e);
A microwave plasma processing method having the above steps. 2. The microwave plasma processing method according to claim 1, wherein the substrate holding table is brought close to the dielectric plate, the dielectric plate is heated and then lowered, and an empty discharge is performed prior to the substrate processing. In a microwave plasma processing method of performing plasma processing on a substrate by guiding a plasma gas generated by microwaves supplied through a dielectric plate to an upper part in a vacuum vessel to a substrate held on a vertically movable substrate holding table,
A microwave plasma processing method, further comprising an electric heater attached near the dielectric plate, wherein the heater heats the dielectric plate prior to the plasma processing of the substrate. In a microwave plasma processing apparatus that performs plasma processing on a substrate by guiding a plasma gas generated by microwaves supplied through a dielectric plate to an upper portion in a vacuum vessel to a substrate held on a vertically movable substrate holding table with a heater,
A vacuum vessel having a plasma generation unit and a reaction chamber continuous therebelow,
A gas flow rate control valve for controlling a flow rate of the reaction gas supplied to the plasma generation unit,
An exhaust pump that exhausts from the reaction chamber and decompresses the inside of the vacuum vessel;
A substrate holder with a heater that can be moved up and down in the vacuum vessel and made accessible to the dielectric plate as needed,
While supplying the reaction gas into the vacuum container, the inside of the vacuum container is evacuated and the reaction gas is plasma-discharged while maintaining a predetermined gas atmosphere to process the substrate, while raising the substrate holder when the substrate is not processed. A controller for heating the dielectric plate with the substrate holding table,
A microwave plasma processing apparatus comprising: 6. The microwave plasma processing apparatus according to claim 5, wherein the dielectric plate is a quartz plate. 6. A cassette accommodating chamber connected to a vacuum container, and a cassette accommodated in the cassette accommodating chamber and loaded with a plurality of substrates, wherein the substrates are carried into and out of the vacuum container one by one from the cassette. 6. The microwave plasma processing apparatus of item 6. 8. The microwave plasma processing apparatus according to claim 7, wherein the controller heats the dielectric plate by raising the substrate holding table so as to approach the dielectric plate during replacement of the cassette. In a microwave plasma processing apparatus that performs plasma processing on a substrate by guiding a plasma gas generated by microwaves supplied through a dielectric plate to an upper portion in a vacuum vessel to a substrate held on a vertically movable substrate holding table,
A microwave plasma processing apparatus comprising an electric heater for heating the dielectric plate.

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