JP3127766B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a device using a semiconductor such as a thin film transistor and various sensors utilizing a semiconductor, a solar cell, and the like. Such as plasma etching for etching a formed film according to a predetermined pattern and surface modification of a substrate by plasma.
Related to plasma treatment.

[0002]

2. Description of the Related Art In general, when high-density plasma is required in plasma processing, the excitation gas is turned into plasma by thermions emitted by heating the filament by applying power, and the processing gas is turned into ions by the ions in the plasma. Is used to excite and generate plasma.

As an example of an apparatus used for such a plasma processing, there is a plasma processing apparatus shown in FIG. This apparatus has a plasma generation chamber 1 and a processing chamber 2 connected to the chamber 1, and the chambers 1 and 2 are grounded. A filament 3 is installed in the plasma generation chamber 1 as a plasma source, and a DC power supply 4 is connected to the filament 3. An ion extraction electrode 5 is provided below the filament 3, and the electrode 5 and a base holder 1 described later are provided.
The DC power supply 6 is connected between the DC power supply 0. Further, a gas supply unit 7 for exciting gas is connected to the plasma generation chamber 1 by piping, and connected to the gas supply unit 7 via mass flow controllers 711, 712... And valves 721, 722. A gas source 73 of one or more excitation gases
1, 732... Are included. Furthermore, plasma generation chamber 1
A ring-shaped solenoid magnet 8 for converging ions in the generated plasma toward the processing chamber 2 is disposed on the outer periphery of the magnet.

A substrate holder 10 is provided below the processing chamber 2, and the holder 10 is provided with a heater 10a for heating the substrate S2 mounted thereon to a processing temperature. When the substrate S2 is heated by radiant heat, the heater 10a
Is separated from the holder 10. Further, a cooler may be used instead of the heater 10a as necessary. A high-frequency power supply 12 is connected to the holder 10 via a matching box 11, and further a DC power supply 13 or 14 is connected to the holder 10. The changeover switch 15 switches between the power supplies 13 and 14. When the substrate S2 placed on the holder 10 is conductive, the processing speed can be controlled by controlling the incident plasma by applying a DC voltage from the DC power supplies 13 and 14, and when the substrate S2 is electrically insulating, the high-frequency power supply 12 can be used. The processing speed can be controlled by controlling the incident plasma by applying a high frequency voltage.

[0005] A ring-shaped gas injection pipe 16 is arranged above the holder 10, and the pipe 16 has a large number of gas injection holes on a lower surface portion facing the holder 10. A gas supply section 18 for a plasma processing gas is connected to the gas ejection pipe 16 via a gas introduction pipe 17. Gas supply unit 18
Are the mass flow controllers 181a, 181b,.
And 1 connected via valves 182a, 182b...
Alternatively, two or more plasma processing gas sources 183a,
83b are included. The reason why the excitation gas supply unit 7 and the plasma processing gas supply unit 18 are connected to the containers 1 and 2 using separate pipes is that when the two gases are mixed, particles that become dust are generated. This is because the surface of the substrate to be processed S2 and the inside of the chambers 1 and 2 are easily contaminated. The processing chamber 2 is provided with a ring-shaped solenoid magnet 9 along its outer peripheral wall, and an exhaust device 19 is connected to the processing chamber 2 by piping. The magnet 9 transfers the ions to the substrate S2 on the holder 10.
To converge to

According to the plasma processing apparatus, the substrate S2
Is supported on the base holder 10 and the chambers 1 and 2 are set to a predetermined degree of vacuum by the operation of the exhaust device 19. Next, an excitation gas is introduced into the plasma generation chamber 1 from the gas supply unit 7, and a DC power is applied to the filament 3 from the power supply 4. Thereby, thermoelectrons are emitted from the heated filament 3, and the introduced excitation gas is turned into plasma. Then, the ions in the plasma are accelerated by the potential difference formed between the ion extraction electrode 5 and the substrate holder 10 by the application of the voltage from the DC power supply 6 and proceed into the processing chamber 2. On the other hand, a plasma processing gas is introduced from the gas supply unit 18 to the vicinity of the substrate S2 via the gas introduction pipe 17 and the gas ejection pipe 16. The ions supplied from the plasma generation chamber 1 are converged on the substrate S2 under the magnetic field of the solenoid magnet 9, and the plasma processing gas introduced near the substrate S2 is turned into plasma by the ions, and the surface of the substrate S2 has a desired surface. Is performed. At this time, when the plasma processing gas is the etching gas, the etching is performed, when the plasma processing gas is the film formation gas, the film is formed, and when the plasma processing gas is the surface reforming gas, the substrate surface is reformed.

[0007]

However, in this plasma treatment, if the pressure in the chambers 1 and 2 is high, the filament 3 is likely to be broken, so that it is necessary to keep the chamber at a relatively high vacuum. In this case, the cost is higher than the plasma treatment under normal pressure, and it is difficult to increase the degree of vacuum when the object to be treated is a material such as plastic which is easily vaporized under reduced pressure.

[0008] Also, in the case of plasma processing under a high vacuum degree, when oxygen (O) plasma is generated using a gas containing, for example, oxygen (O ₂ ) gas as an exciting gas, the total processing time is about 10 hours. The filament 3 breaks. Generally, a high melting point metal such as tungsten (W) is used for the filament. When a gas containing, for example, an oxygen element or a halogen element is used as the excitation gas as well as the oxygen gas, an oxide or a halide of the filament metal is generated and vaporized, and the filament is consumed. There is a problem in that the life of the metal oxide, metal halide, and the like are reduced as impurities and adhere to the surface of the substrate to be processed and various parts in the vacuum vessel as impurities to contaminate them.

[0009]

An object of the present invention is to provide a plasma processing apparatus having a plasma generating apparatus, a processing chamber connected to the plasma generating apparatus, and a plasma processing apparatus, and a plasma processing apparatus using the plasma processing apparatus.
A plasma treatment method , in which a plasma treatment can be performed on an object to be processed even under a low vacuum or normal pressure, and even when a plasma source gas containing an active gas containing an oxygen element, a halogen element, or the like is used, a plasma source is used. Low consumption of the gas, stable use over a long period of time, and low consumption of the plasma source suppresses the generation of impurities, thereby suppressing the contamination of the plasma generator, the processing chamber, and the workpiece. Accordingly, an object of the present invention is to provide a plasma processing apparatus and a plasma processing method capable of performing predetermined plasma processing on an object to be processed.

[0011]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted research and found the following facts. That is, when a plasma source made of a carbon-containing material is used instead of the conventional filament made of a high melting point metal such as tungsten, and a raw material gas is introduced near the plasma source and the microwave is irradiated to the plasma source, the gas becomes Is converted into a plasma, and the plasma can be formed not only under a high vacuum, but also under a low vacuum or normal pressure. Further, even when a gas containing an active gas containing an oxygen element, a halogen element, or the like is used as a source gas, the plasma source is not easily consumed.

Based on the above fact, the plasma processing of the present invention
The apparatus includes a plasma generation device, a plasma generation chamber,
The apparatus includes means for supplying a plasma source gas to the plasma generation chamber, a plasma source made of a carbon-containing substance provided in the plasma generation chamber, and means for irradiating the plasma source with microwaves . The plasma processing apparatus of the present invention, said plasma generating device, which is provided continuously to the plasma generating apparatus, it is assumed that a processing chamber for installing an object to be processed.

Examples of the carbon-containing substance used in the plasma generator and the plasma processing apparatus include carbon (C) alone and silicon carbide (SiC).
Further, it is conceivable that the plasma source made of the carbon-containing substance is supported at a predetermined position in the plasma generation chamber by the plasma source supporting means. As a material of such a support means, a high melting point metal such as tungsten, an electrically insulating substance such as glass, ceramics, or the like can be used. The plasma source made of a carbon-containing material is typically considered to be, for example, a powder of a carbon-containing material supported by being attached to a mesh-like supporting means.

[0014] The plasma generating apparatus of the present invention may be provided with an exhaust means capable of keeping the plasma generating chamber in a predetermined vacuum state for controlling the plasma. Also, the plasma processing apparatus of the present invention may be provided with an exhaust unit capable of setting the plasma generation chamber and the processing chamber to a predetermined vacuum state for controlling the plasma and controlling the processing of the object to be processed. In this case, the exhaust means may be provided for each of the plasma generation chamber and the processing chamber, or a common means may be provided for both.

In the plasma generating apparatus and the plasma processing apparatus according to the present invention, as in the conventional apparatus, ions in the plasma generated in the plasma generating chamber are converged toward the plasma processing chamber around the plasma generating chamber. For example, a ring-shaped magnet may be provided, or a ring-shaped magnet may be provided around the plasma processing chamber to converge the ions toward the object to be processed.

[0016] In addition, Oite to the plasma processing apparatus of the present invention
Is provided with means for accelerating and introducing ions in the plasma generated in the plasma generation chamber toward the processing chamber . As the ion accelerating and introducing means, for example, a means including an ion extraction electrode as shown in FIG. 2 can be mentioned. In this case, it is conceivable to provide a means for applying a DC voltage between the ion extraction electrode and the electrode and the means for supporting the object in the processing chamber.

Further, the plasma processing apparatus of the present invention may be provided with a means for supplying a processing gas to the processing chamber in which an object to be processed is installed so that a predetermined processing can be performed using the processing gas. . As a means for introducing the processing gas, it is conceivable to employ a piping device capable of introducing the gas into the vicinity of the object to be processed, and an example thereof includes a ring-shaped gas ejection pipe in the conventional apparatus shown in FIG. Things can be mentioned.

Further, in the plasma processing apparatus of the present invention, a DC power supply or a high-frequency power source for applying a voltage to the processing object support means in the processing chamber so that the incident plasma can be controlled to control the processing speed of the processing object. It is conceivable to connect a power supply or both.

[0019]

According to the plasma generator of the present invention, a plasma raw material gas is introduced into a plasma generation chamber, and a microwave is irradiated to a plasma source by microwave irradiation means, whereby the gas is turned into plasma. This is considered to be due to the proximity effect in which the carbon-containing substance of the plasma source irradiated with the microwave acts like a catalyst to promote the plasma conversion of the plasma raw material gas.

The above-described plasma generation can be performed not only under a relatively high vacuum, but also under a low vacuum or normal pressure. Also, when a gas containing an active gas containing an oxygen element, a halogen element, or the like, which conventionally easily reacts with a high melting point metal such as tungsten to generate a metal oxide or a metal halide, is used. In addition, since the carbon-containing substance hardly reacts with such an active gas, the plasma source is hardly consumed.

[0021]

The plasma processing apparatus of the present invention and the apparatus
In such a plasma processing method, there is provided a means for accelerating and introducing ions in the plasma thus generated into the processing chamber.
Therefore, the ions in the plasma are accelerated and introduced into the processing chamber in which the object to be processed is installed, and a predetermined process such as ion implantation or etching is performed on the object by the action of the ions. . Here, means for supplying a processing gas to the processing chamber is provided.
When a constant processing gas is supplied, the processing gas is turned into plasma by the ions accelerated into the processing chamber, and a predetermined process is performed on the object under the plasma.
That is, when the processing gas is an etching gas,
When the etching is a film forming gas, the film is formed.
It is like.

In addition, since the plasma source is hardly consumed for the above-mentioned reason, it is possible to prevent impurities derived from the plasma source from adhering to the surface of the workpiece, the plasma generation chamber, and the processing chamber.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a plasma processing apparatus B using a plasma generator A according to one embodiment of the present invention. This apparatus is different from the conventional apparatus shown in FIG.
A ring-shaped cavity 20 externally fitted in the cavity, a microwave power supply 21 connected to the cavity 20, and a cavity 2
And a tuner 22 for changing the capacity of zero.
The inside thereof has a mesh-shaped plasma source support means 23a and a powdery plasma source 23 made of a carbon-containing substance supported so as to adhere to the support means 23a. Other configurations are the same as those of the apparatus shown in FIG.
Components that are the same as those shown in FIG. 2 are given the same reference numerals as in FIG.

The reason why the mesh-shaped plasma source support means 23a and the powdery plasma source 23 adhered to the support means 23a are adopted is that the plasma source gas supplied from the gas source 7 is used for the contact area with the plasma source 23. To make the gas into a plasma while allowing the gas to pass through. Here, the plasma generation chamber 1, the cavity 20, the microwave power source 21, the plasma source 23, and the plasma source support means 23a constitute a plasma generator A. Although the magnet 8 in the conventional device is not used here, the magnet 8 may be provided as shown by a two-dot chain line in FIG.

According to the plasma processing apparatus B, the plasma processing is performed as follows. First, after supporting the substrate S1 on the substrate holder 10, the exhaust device 19 is provided as necessary.
The chambers 1 and 2 are set to a predetermined degree of vacuum by the operation described above. Next, an excitation gas is introduced from the gas supply unit 7 into the plasma generation chamber 1 as a plasma raw material gas.
The microwave power applied to the cavity 20 from 1 is supplied to the plasma source 23. Matching in microwave irradiation is performed by changing the capacity of the cavity 20 by the tuner 22. Thereby, the introduced excitation gas is turned into plasma.

Then, the ions in the plasma are accelerated by a potential difference formed between the ion extraction electrode 5 and the base holder 10 by applying a voltage from the DC power supply 6, and
Proceed in the direction of the substrate holder 10. At the same time, a plasma processing gas is introduced from the gas supply unit 18 to the vicinity of the substrate S1 via the gas introduction pipe 17 and the gas ejection pipe 16. The ions supplied from the plasma generation chamber 1 are converged on the substrate S1 under the magnetic field of the solenoid magnet 9, and the plasma processing gas introduced near the substrate S1 is excited by the ions to be turned into plasma, and the surface of the substrate S1 is turned on. Is subjected to a desired plasma treatment.

When the plasma processing gas is not introduced from the gas supply unit 18, the surface of the substrate S1 is subjected to a desired process such as ion implantation or etching by the ions converged on the substrate S1. At this time, the processing gas supply unit 18 can be omitted. Here, the ions in the plasma generated in the plasma generation chamber 1 are accelerated and introduced into the processing chamber 2 using the ion extraction electrode 5, but a voltage is applied between the ion extraction electrode 5 and the base holder 10. Instead, the plasma generated in the generation chamber 1 may be diffused into the processing chamber 2 and the plasma processing gas may be turned into plasma by the ions in the plasma.

In the processing of the substrate S1, if necessary, the DC power supply 13 or 1
4, a DC voltage is applied, and when the substrate S1 is electrically insulating, a high-frequency voltage is applied from the high-frequency power supply 12, thereby controlling the processing speed. As described above, desired plasma processing can be performed on the surface of the base S1 even when the inside of the chambers 1 and 2 is set to a relatively low vacuum or normal pressure. Also, when a gas containing an active gas containing an oxygen element and a halogen element is used as the excitation gas, the consumption of the plasma source 23 due to the application of the electric power is small, and the impurities on the surface of the substrate S1 and the inside of the chambers 1 and 2 are reduced. Is reduced.

Next, a specific example in which the apparatus shown in FIG. 1 is used as a plasma CVD apparatus will be described. Example 1 Formation of silicon dioxide (SiO ₂ ) film ・ Substrate: 6 inch silicon (Si) wafer Equipment conditions ・ Plasma source: carbon particles (particle diameter: 0.5 mm) ・ Plasma source supporting means: diameter 100 mm × thickness 3 mm mesh size # 100 ・ Plasma generation chamber size: diameter 100 mm × 150 mm Film forming conditions ・ Film forming vacuum degree: 760 Torr (normal pressure) ・ Microwave power: 250 W ・ Magnetic field strength: 100 Gauss ・ Excitation gas (plasma raw material gas): Argon (Ar) ) Gas 1200 sccm ・ Film source gas: monosilane (SiH ₄ ) gas 100 sccm Oxygen (O ₂ ) gas 200 sccm ・ Substrate temperature: 200 ° C. ・ Injection plasma control: DC power supply used, 10 V Film formation result Film thickness: 10000Å Film formation rate : 6000Å / min. Thickness uniformity: ± 5% The adulteration of silicon dioxide film was made S
It was below the detection limit as measured by IMS analysis. Further, when the same processing was repeated by changing the substrate, the plasma source 23 did not cause a problem in film formation due to consumption even with a total film formation time of 50 hours. Comparative Example 1 Formation of Silicon Dioxide (SiO ₂ ) Film A conventional plasma processing apparatus shown in FIG. 2 was used instead of the apparatus shown in FIG. A silicon dioxide film was formed on the substrate under the same conditions as in Example 2 except for the substrate temperature and the incident plasma control conditions.
The degree of vacuum for film formation was 1 × 10 ⁻⁴ Torr. The material of the filament 3 was tungsten, and the excitation gas was turned into plasma by applying a DC power of 420 W (7 V, 60 A) to the filament. The strength of the magnet 8 was set to 200 Gauss. Film formation result • Film thickness: 1000 ° • Film formation rate: 100 ° / min • Film thickness uniformity: ± 15% SIMS was used to determine the amount of impurities mixed in the formed silicon dioxide film.
As a result of analysis by an analytical method, tungsten atoms considered to be derived from the filament 3 in the film had a density of about 5 × 1.
It was detected at 0 ²² atoms / cm ³ . When the same processing was repeated with the substrate changed, the total film forming time was about 1 hour.
The filament broke in time.

In the film formation according to Example 1, it was found that a film formation speed approximately 60 times that of the film formation according to Comparative Example 1 was obtained, that is, an extremely high plasma density was obtained. The film thickness uniformity of the film of Example 1 was also three times better than that of Comparative Example 1. The life of the plasma source 23 used in Example 1 was at least 50 times longer than that of the filament 3. Further, impurities mixed in the film were also reduced to below the detection limit of the SIMS analysis method as compared with the silicon dioxide film of Comparative Example 1.

The film formation according to Example 1 could be performed under normal pressure. Next, a specific example using the apparatus shown in FIG. 1 as an etching apparatus will be described. Example 2 Etching of silicon (Si) substrate ・ Substrate: 6 inch Si wafer Device conditions ・ Plasma source: carbon particles (particle diameter: 0.5 mm) ・ Plasma source support means: diameter 100 mm × thickness 3 mm mesh size # 100 ・ plasma generation Chamber size: diameter 100 mm x 150 mm Etching conditions-Deposition vacuum: 5 x 10 ^-2 Torr-Microwave power: 250 W-Magnetic field strength: 100 Gauss-Exciting gas (plasma raw material gas): Argon (Ar) gas 1200 sccm-Etching Gas for use: Carbon tetrafluoride (CF ₄ ) gas 200 sccm ・ Substrate temperature: 100 ° C. ・ Injection plasma control: Use of DC power supply, 50 V Etching result ・ Etching rate: 1000ｍｉｎ / min ・ Uniformity in etching surface: ± 6% ・Etched shape: Forward taper Same processing The place that was repeated by changing the substrate, the plasma source 23 is etched on the problems due to exhaustion even total etching time of about 2000 hours did not occur. Comparative Example 2 Etching of Silicon (Si) Substrate The conventional plasma processing apparatus shown in FIG. 2 was used instead of the apparatus shown in FIG. 1, and the substrate, the magnetic field strength by magnet 9, excitation gas, etching gas, substrate temperature, and incident plasma were used. The silicon substrate was etched under the same control conditions as in Example 2.
The etching vacuum degree was 1 × 10 ⁻³ Torr. The material of the filament was tungsten, and the excitation gas was turned into plasma by applying a DC power of 420 W (7 V, 60 A) to the filament. The strength of the magnet 8 was set to 50 Gauss. Etching result ・ Etching rate: 80 ° / min ・ Etching uniformity: ± 23% ・ Etching shape: Reverse taper When the same treatment was repeated with changing the substrate, the filament was cut in about 0.5 hours in total etching time. .

It can be seen that the etching rate of Example 2 was about 12 times that of the etching rate of Comparative Example 2, that is, a higher plasma density was obtained. The uniformity in the etched surface was also improved in the etching according to Example 2 as compared with the etching according to Comparative Example 2. The etching shape was reverse tapered in Comparative Example 2, whereas it was forward tapered in Example 2, and anisotropic etching was performed.

The etching in Example 2 could be performed under a lower vacuum than the etching in Comparative Example 2.

[0035]

[0036]

According to the present invention, there is provided a plasma processing apparatus having a plasma generating apparatus and a processing chamber connected to the plasma generating apparatus, and a plasma generated by the plasma processing apparatus.
In the treatment method , the object to be treated can be subjected to plasma treatment even under a low vacuum or normal pressure, and even when using a plasma source gas containing an active gas containing an oxygen element or a halogen element, Low consumption, stable use over a long period of time, and low consumption of the plasma source suppresses the generation of impurities, thereby suppressing contamination of the plasma generation chamber, the plasma processing chamber, and the workpiece. Thus, it is possible to provide a plasma processing apparatus and a plasma processing method capable of performing predetermined plasma processing on an object to be processed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a plasma processing apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an example of a conventional plasma processing apparatus.

[Explanation of symbols]

 Reference Signs List A Plasma generator B Plasma processing apparatus 1 Plasma generation chamber 2 Plasma processing chamber 3 Filament 4, 6, 13, 14 DC power supply 5 Ion extraction electrode 7 Exciting gas supply unit 8, 9 Solenoid magnet 10 Base holder 10a Heater 11 Matching box DESCRIPTION OF SYMBOLS 12 High frequency power supply 15 Changeover switch 16 Gas ejection pipe 17 Gas introduction pipe 18 Gas supply part for plasma processing 19 Exhaust device 20 Cavity 21 Microwave power supply 22 Tuner 23 Plasma source 23a Plasma source support means S1, S2 Substrate to be processed

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H05H 1/46 H01L 21/302 B (56) References JP-A-5-238718 (JP, A) JP-A-8-60364 ( JP, A) JP-A-55-141729 (JP, A) JP-A-2-124797 (JP, A) JP-A-5-74713 (JP, A) JP-A-7-245193 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H01L 21/31 C23C 16/50 C23F 4/00 H01L 21/205 H01L 21/3065 H05H 1/46

Claims (4)

(57) [Claims] 1. A plasma generation chamber, means for supplying a plasma source gas to the plasma generation chamber, and a plasma source made of a carbon-containing substance installed in the plasma generation chamber,
A plasma generator having means for irradiating the plasma source with microwaves , and an object to be processed connected to the plasma generator are provided.
Processing chamber, and the ions in the plasma generated by the plasma generator.
And a means for accelerating and introducing the gas into the processing chamber.
Plasma processing equipment. 2. A means for supplying a processing gas to the processing chamber.
The plasma processing apparatus according to claim 1, further comprising: 3. The plasma processing apparatus according to claim 1,
A plasma processing method, placing an object to be processed into the processing chamber, plug into the plasma generation chamber in the plasma generator
Introduce zuma raw material gas and use microwave irradiation means
By irradiating the plasma source with microwaves,
Of the plasma, and convert the ions in the plasma to the ions
Accelerated introduction into the processing chamber by accelerated introduction means , and a predetermined process is performed on the workpiece by the action of the accelerated ions.
Performing a plasma treatment method. 4. A means for supplying a processing gas to the processing chamber.
And introducing a processing gas into the processing chamber,
The ions accelerated into the processing chamber by the acceleration introducing means
The processing gas is turned into a plasma, and the
4. The plasma according to claim 3, wherein a predetermined process is performed on the workpiece.
Processing method.