JP2007142175A - Plasma processing method and plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing method and a plasma processing device capable of reducing manufacturing cost of an electrode, as well as, capable of stably plasma processing, without damaging the electrode even when in a plasma that uses chlorine gas. <P>SOLUTION: An electrode 2 and a substrate 6, consisting of carbon material are arranged with open spacing in a chamber 1 and in the gaseous atmosphere containing halogen gas (chlorine gas) under the atmospheric pressure or close to the atmospheric pressure. Plasma 15 is generated between the electrode 2 and the substrate 6, by supplying high-frequency electric power to the electrode 2 from a high-frequency power supply 5. Furthermore, while heating the substrate 6 with a substrate heater 7 so that the substrate temperature exceeds the melting point of the compound of the halogen gas and the substrate material, the surface of the substrate 6 is processed by using the plasma 15 that is generated between the electrode 2 and the substrate 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma process method and a plasma process apparatus, and more particularly, to a plasma process method and a plasma process apparatus that perform processing using plasma generated under atmospheric pressure or a pressure near atmospheric pressure.

  2. Description of the Related Art Conventionally, as an apparatus using a plasma process method, there is a parallel plate type plasma etching apparatus in the field of a semiconductor device typified by a semiconductor memory device or the like and an FPD (Flat Panel Display). In this etching apparatus, plasma is generated by applying high-frequency power between vertically opposed electrodes, and processing such as etching is performed on the substrate. Active ions such as ions and radicals generated in the plasma are processed. The process proceeds when the reactive species reacts with molecules on the substrate surface. The electrodes used in this plasma etching apparatus must be resistant to the reactive species and heat in the plasma. As shown in FIG. 7, the surface of the metal electrode 51 is interposed with an insulating member 52 made of ceramics such as alumina. Generation of plasma 53 has been performed. In the case of an electrode made of a metal material on the surface that comes into contact with the plasma, the electrode itself reacts violently with the plasma in chlorine gas plasma, etc., so it is necessary to install a chemically stable substance on the electrode surface. Met.

  On the other hand, an electrode made of a carbon material is also used in addition to the metal electrode. A carbon material is suitable as a material for a member of a semiconductor manufacturing apparatus because it has excellent electrical conductivity and chemical stability and can be easily purified. For example, in an MO-CVD (Metal Organic-Chemical Vapor Deposition) apparatus which is one of apparatuses for forming a single crystal thin film of a compound semiconductor, a carbon material is used as a susceptor material for heating a substrate. Is used. Such a non-sliding member does not generate impurities in the apparatus such as dust generation.

  However, when a general carbon material is used as an electrode for plasma generation, there is a problem that fine particles constituting the material structure fall off during plasma generation, and the electrode itself is consumed quickly. There was a problem such as contaminating. In order to solve these problems, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 7-37861) discloses a technique describing a method for producing a carbon material itself.

  However, a ceramic member such as alumina used for the insulating member 52 shown in FIG. 7 requires a great deal of cost and time to manufacture. Further, when a structure in which a ceramic member is arranged on the surface of the metal electrode is used, if there is a gap between the metal electrode 51 and the ceramic insulating member 52 in FIG. 7, local discharge occurs at that portion. Therefore, it is necessary to bring them into close contact with each other. However, in the case of a close contact structure, there is a problem in that the metal electrode 51 expands due to the heat generated by the plasma 53 and the insulative ceramic insulating member 52 is damaged.

Moreover, in order to solve the problem when using an electrode made of a carbon material, Patent Document 1 discloses a carbon electrode for plasma etching that consumes less, but a special material is used, and the electrode is manufactured. It is considered that the cost and time for the cost are not reduced.
JP 7-37861 A

  Accordingly, an object of the present invention is to provide a plasma processing method and a plasma processing apparatus that can perform a stable plasma process without damaging the electrode even in plasma using chlorine gas, and can reduce the manufacturing cost of the electrode. There is.

  Another object of the present invention is to perform surface flattening treatment of a compound semiconductor at a low cost, and also to suppress the occurrence of physical damage on the surface of a general semiconductor substrate. An object of the present invention is to provide a plasma processing method and a plasma processing apparatus.

In order to achieve the above object, a plasma processing method of the present invention comprises:
A plasma process method for performing a plasma process on a substrate made of a compound semiconductor material disposed in the processing chamber by turning a process gas introduced into the processing chamber into a plasma state,
The process gas contains at least a halogen gas,
In the processing chamber and in a gas atmosphere containing at least the halogen gas under a pressure of 10 Torr to 5 atm, an electrode made of a carbon material and the substrate are arranged with a space therebetween,
Heating the substrate to a temperature equal to or higher than the boiling point of the compound of the halogen gas and the substrate material;
A surface of the substrate is processed by plasma generated between the electrode and the substrate by supplying high-frequency power to the electrode.

In general, when an electrode with a conductor exposed on its surface, such as an electrode made of a carbon material, is used without covering the electrode surface with an insulating member, dielectric barrier discharge cannot be performed. It is considered that a stable plasma process cannot be performed due to discharge. However, according to the plasma process method having the above structure, even when plasma is generated in a gas atmosphere containing at least a halogen gas under a pressure of 10 Torr to 5 atm using an electrode made of a carbon material, the compound semiconductor material Since the substrate made of is used as a processing target, the conductors do not face each other and arc discharge does not occur. As a result, a stable plasma process can be performed.
Further, in a gas atmosphere containing at least a halogen gas under a pressure of 10 Torr to 5 atm, a high frequency power is supplied to the electrode while heating the substrate to a temperature equal to or higher than the boiling point of the compound of the halogen gas and the substrate material. By generating plasma between the substrate and the substrate and processing the surface of the substrate with the generated plasma, damage to the electrode made of carbon material and contamination of the substrate surface are suppressed, and the substrate surface is not damaged. This is thought to be because ions in atmospheric pressure plasma often collide with any molecule or atom before colliding with the surface of the electrode or substrate, reducing direct collision with the electrode or substrate surface. . As a result, even in plasma using halogen gas, a stable plasma process can be performed without damaging the electrode, and the manufacturing cost of the electrode can be reduced. Also, in processing a substrate made of a compound semiconductor, physical collision of ions to the substrate surface hardly occurs, so that not only physical damage to the substrate surface can be suppressed, but also chemical reaction. Since the ion assist effect is reduced, excessive reaction can be suppressed. Therefore, it is possible to perform the surface planarization treatment of the substrate made of a compound semiconductor that requires no damage on the surface crystallographically at a low cost. Similarly, in general surface processing of a semiconductor substrate, occurrence of physical damage on the substrate surface can be suppressed, and surface flattening processing of the semiconductor substrate can be performed at low cost.

  Moreover, the plasma process method of one Embodiment sets the space | interval of the electrode which consists of the said carbon material, and the said board | substrate to 100 micrometers-5 mm, It is characterized by the above-mentioned.

  According to the plasma process method of the above-described embodiment, the distance between the electrodes can be increased as compared with an electrode in which a conventional insulating member is disposed because no insulating member is interposed between the electrodes. Thereby, the in-plane uniformity of the plasma process can be improved. In addition, the surface of the substrate made of a compound semiconductor material can be processed in a state where there is no disorder of the crystal lattice, thereby improving the electrical characteristics and yield of the semiconductor element to be produced.

In addition, the plasma processing method of one embodiment includes:
The state of the electrode made of the carbon material is managed based on a voltage at which discharge is started when high-frequency power is supplied to the electrode.

  According to the plasma process method of the above-described embodiment, a large-scale apparatus modification is performed by managing the state of the electrode made of a carbon material based on the voltage at which discharge is started when high-frequency power is supplied to the electrode. Therefore, it is possible to detect a change with time of the electrode made of the carbon material, and it is possible to continuously perform a stable plasma process.

In addition, the plasma processing method of one embodiment includes:
Plasma is generated between the electrode and the substrate while the electrode is rotated by a rotation mechanism.

  According to the plasma process method of the above-described embodiment, plasma is generated between the electrode and the substrate while the electrode is rotated by a rotation mechanism, and the substrate surface is treated by the generated plasma, whereby the electrode and the plasma are brought into contact with each other. Since the surface always changes, it is possible to prevent a specific part of the electrode from being heated locally. Thereby, the lifetime of the electrode can be extended, and the maintenance cycle can be extended. Further, for example, when a linear region along the generatrix of the surface of a cylindrical electrode having a central axis as a rotation axis is brought close to the substrate surface, together with the surface of the electrode rotating the process gas supplied into the processing chamber Therefore, the process gas can be efficiently supplied to the plasma generation region.

The plasma processing apparatus of the present invention is
A plasma process apparatus for performing a plasma process on a substrate made of a compound semiconductor material disposed in the processing chamber by turning the process gas introduced into the processing chamber into a plasma state,
The process gas contains at least a halogen gas,
An electrode made of a carbon material disposed at a distance from the substrate in the processing chamber;
A high frequency power supply unit for supplying high frequency power to the electrode;
A heating unit for heating the substrate so as to have a temperature equal to or higher than the boiling point of the compound of the halogen gas and the substrate material;
The substrate is heated by the heating unit so that the temperature is higher than the boiling point of the compound of the halogen gas and the substrate material in a gas atmosphere containing at least the halogen gas under a pressure of 10 Torr to 5 atm in the processing chamber. And generating plasma between the electrode and the substrate by supplying high-frequency power to the electrode from the high-frequency power supply unit, and processing the surface of the substrate with the generated plasma. And

According to the plasma process apparatus having the above-described configuration, even when plasma is generated in a gas atmosphere containing at least a halogen gas under a pressure of 10 Torr to 5 atm using an electrode made of a carbon material, it is made of a compound semiconductor material. Since the substrate is used as the processing object, the conductors do not face each other, and arc discharge hardly occurs. As a result, a stable plasma process can be performed.
In addition, in a gas atmosphere containing at least halogen gas under atmospheric pressure or near atmospheric pressure, the heating unit heats the substrate to a temperature equal to or higher than the boiling point of the compound of the halogen gas and the substrate material, from the high frequency power supply unit. By supplying high-frequency power to the electrode, plasma is generated between the electrode and the substrate, and by processing the surface of the substrate with the generated plasma, damage to the electrode made of carbon material and contamination of the substrate surface are suppressed. Does not damage the substrate surface. This is thought to be because ions in atmospheric pressure plasma often collide with some molecule or atom before colliding with the surface of the electrode or substrate, reducing direct collision with the electrode or substrate surface. . As a result, even in plasma using halogen gas, a stable plasma process can be performed without damaging the electrode, and the manufacturing cost of the electrode can be reduced. Also, in the processing of a substrate made of a compound semiconductor, physical collision of ions to the substrate surface hardly occurs, so that not only physical damage to the substrate surface can be suppressed, but also chemical reaction can be prevented. Since the ion assist effect is reduced, excessive reaction can be suppressed. Therefore, it is possible to perform the surface planarization treatment of the substrate made of a compound semiconductor that requires no damage on the surface crystallographically at a low cost. Similarly, in general surface processing of a semiconductor substrate, occurrence of physical damage on the substrate surface can be suppressed, and surface flattening processing of the semiconductor substrate can be performed at low cost.

In addition, the plasma processing apparatus of one embodiment,
The state of the electrode is managed based on a voltage at which discharge is started when high-frequency power is supplied from the high-frequency power supply unit to the electrode.

  According to the plasma process apparatus of the above embodiment, a large-scale modification of the apparatus is performed by managing the state of the electrode made of the carbon material based on the voltage at which discharge is started when high-frequency power is supplied to the electrode. Therefore, it is possible to detect a change with time of the electrode made of the carbon material, and it is possible to continuously perform a stable plasma process.

In addition, the plasma processing apparatus of one embodiment,
A rotation mechanism for rotating the electrode;
Plasma is generated between the electrode and the substrate while the electrode is rotated by the rotating mechanism.

  According to the plasma processing apparatus of the above embodiment, plasma is generated between the electrode and the substrate while the electrode is rotated by a rotating mechanism, and the substrate surface is processed by the generated plasma, whereby the electrode and the plasma come into contact with each other. Since the surface always changes, it is possible to prevent a specific part of the electrode from being heated locally. Thereby, the lifetime of the electrode can be extended, and the maintenance cycle can be extended. Further, for example, when a linear region along the generatrix of the surface of a cylindrical electrode having a central axis as a rotation axis is brought close to the substrate surface, together with the surface of the electrode rotating the process gas supplied into the processing chamber Therefore, the process gas can be efficiently supplied to the plasma generation region.

  As is clear from the above, according to the plasma processing method and the plasma processing apparatus of the present invention, when the substrate surface is processed by generating plasma with a gas containing halogen, the carbon material is used under the pressure near atmospheric pressure. By using such an electrode, it is not necessary to produce a special carbon material or ceramic parts such as alumina, and the production and operation costs of the apparatus can be reduced.

  Hereinafter, a plasma processing method and a plasma processing apparatus of the present invention will be described in detail with reference to embodiments shown in the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of a plasma processing apparatus using the plasma processing method according to the first embodiment of the present invention.

  The plasma processing apparatus according to the first embodiment includes a chamber 1 as an example of a processing chamber, an electrode 2 disposed in the chamber 1, one end connected to the electrode 2, and the other end on the upper side of the chamber 1. A protruding power supply member 3, a matching unit 4 having one end connected to one end of the power supply member 3, a high-frequency power source 5 as an example of a high-frequency power supply unit connected to the other end of the matching unit 4, A substrate heater 7 as an example of a heating unit disposed in the chamber 1 and below the electrode 2, an XY stage 8 on which the substrate heater 7 is mounted on the upper side, an outer edge portion of the XY stage 8, and the chamber 1 A bellows 9 that seals between them, an elevating mechanism 10 that moves the XY stage 8 up and down, a process gas supply 11 provided on the upper side of the chamber 1, and a gas supply of the process gas. The flow control device 12 having one end connected to the section 11, the gas cylinder 13 connected to the other end of the flow control device 12, and the exhaust pump 14 provided below the chamber 1 are mainly included. Yes. A substrate 6 made of gallium nitride as an example of a compound semiconductor material is placed on the XY stage 8.

  As shown in FIG. 1, the high frequency power output from the high frequency power source 5 is supplied to the electrode 2 in the chamber 1 through the matching unit 4 and the power supply member 3. The electrode 2 is an electrode made of a carbon material, and has a plate-like shape having a flat surface in FIG. The process gas is supplied from the gas cylinder 13 into the chamber 1 through the flow rate control device 12 and the gas supply unit 11. Here, the process gas refers to a rare gas such as helium or argon that promotes the generation and maintenance of plasma, or a chlorine gas that actually contributes to processing such as etching.

  The substrate heater 7 and the XY stage 8 are made of a metal material and are grounded. An electric field is formed in the space between the electrode 2 and the substrate 6 by applying a high-frequency voltage from the high-frequency power source 5 to the electrode 2 via the matching unit 4 and the power supply member 3. The plasma 15 is generated by exciting the process gas supplied from the gas supply unit 11. The substrate 6 that is the object to be processed is placed on the substrate heater 7 by a transfer unit (not shown) and processed by reactive species such as radicals generated in the plasma 15. At this time, the substrate heater 7 is heated so that the temperature of the substrate 6 becomes equal to or higher than the boiling point of the compound of the halogen gas to be used and the substrate 6. Then, the gas used for processing and the surplus gas are exhausted outside the apparatus by the exhaust pump 14.

  By heating the substrate 6 so that the temperature is equal to or higher than the boiling point of the compound of the halogen gas and the substrate 6 to be used, the compound of the generated halogen gas and the substrate material is sufficiently vaporized and remains on the surface of the substrate 6. Therefore, highly accurate machining is possible.

  In the plasma processing apparatus configured as described above, the plasma process is performed as follows. In the first embodiment, a chlorine gas is used as a halogen gas, a gallium nitride substrate is used as a substrate to be processed, and a process for etching the surface of the gallium nitride substrate will be described as an example.

  First, after the substrate 6 is placed at a predetermined position of the substrate heater 7, the inside of the chamber 1 is evacuated by the exhaust pump 14. Once the inside of the chamber 1 is evacuated, the reproducibility of the situation in the chamber 1 when processing is performed can be improved, and the plasma process can be performed stably.

  Next, a process gas is supplied. The process gas supplied from the gas cylinder 13 is introduced into the chamber 1 by the gas supply unit 11 up to a pressure close to atmospheric pressure while being set to a predetermined mixing ratio by the flow rate control device 12.

  After the process gas is supplied to a predetermined pressure, the XY stage 8 and the substrate heater 7 are raised by the elevating mechanism 10 until the distance between the surface of the substrate 6 and the electrode 2 reaches a predetermined value. The elevating mechanism 10 is installed outside the chamber 1 and connected to the lower part of the XY stage 8 via a bellows 9.

  After setting the distance between the surface of the substrate 6 and the electrode 2, high frequency power is supplied to the electrode 2 from the high frequency power source 5 through the matching unit 4 and the power supply member 3. As a result, an electric field is formed between the electrode 2 and the substrate 6 to excite the supplied plasma process gas and generate plasma 15. After the plasma 15 is generated, the XY stage 8 is driven in the horizontal direction and the entire surface of the substrate 6 is processed.

  Here, the characteristics of generating the plasma 15 with a gas containing chlorine gas using the electrode 3 made of a carbon material under atmospheric pressure or pressure near atmospheric pressure will be described. Conventionally, when a dry etching process is performed using a carbon material electrode in a low-pressure atmosphere, the electrode surface is sputtered, so that fine particles of the carbon material become dust and adhere to the substrate and become contaminated. was there. On the other hand, in this plasma process apparatus, when plasma is generated in a gas atmosphere containing chlorine gas under a pressure near atmospheric pressure, damage to electrodes made of carbon material and contamination of the substrate surface are suppressed. Was confirmed. This is thought to be because ions in atmospheric pressure plasma often collide with some molecule or atom before colliding with the surface of the electrode or substrate, reducing direct collision with the electrode or substrate surface. .

  Therefore, according to the plasma process apparatus using the plasma process method, a stable plasma process can be performed without damaging the electrode 6 even in the plasma using the halogen gas, and the manufacturing cost of the electrode 6 can be reduced. can do.

  In the first embodiment, the plasma 15 is generated by setting the frequency of the high frequency to be supplied to 150 MHz and the distance between the surface of the substrate 6 and the electrode 2 to 3 mm. The mean free path of ions in the plasma at atmospheric pressure is about 0.1 μm, and if the frequency of the high frequency is 150 MHz, the ions are usually almost stationary in the plasma or oscillate and molecules in the plasma. And ions do not reach the electrode 2 surface. In addition, although the electrically neutral radical reaches the surface of the electrode 2, physical collision hardly occurs and only a chemical reaction with the carbon material occurs. The radical that has reacted with the carbon material becomes a low-molecular halogen carbide and is efficiently exhausted, so that polymerization (polymerization) does not occur, and therefore, contamination in the chamber 1 does not occur.

  In addition, the following effects can be obtained by generating chlorine gas plasma under a pressure near atmospheric pressure and performing dry etching or surface processing on the compound semiconductor substrate. In the plasma processing method according to the present invention, plasma is generated under a pressure near atmospheric pressure, and therefore, physical collision of ions to the substrate surface hardly occurs as in the case of the electrode surface described above. Thereby, not only the physical damage of the substrate surface can be suppressed, but also the ion assist effect is reduced for a chemical reaction, so that an excessive reaction can be suppressed. For the above reasons, the surface of the compound semiconductor substrate can be processed in a state where there is no disorder of the crystal lattice, thereby improving the electrical characteristics and the yield of the semiconductor element to be produced.

  Here, in the first embodiment, the gallium nitride substrate is processed as an example, but the substrate material that is damaged by the collision of ions in a low-pressure atmosphere is not necessarily limited thereto. Similar damages occur in other compound semiconductor substrates such as GaAs, and the same effects as described above can be obtained for substrates of these materials by using the plasma processing method of the present invention.

As described above, by using the plasma process method according to the present invention and the plasma process apparatus using the method, it is possible to suppress the consumption of the electrode even when the plasma process is performed using the electrode made of the carbon material. At the same time, contamination of the substrate surface by fine particles generated from the electrode surface can be suppressed. In addition, when a substrate made of a compound semiconductor is used as the treatment substrate, physical damage of ions and excessive chemical reaction on the substrate surface can be eliminated, and surface processing can be performed without disturbing the crystal lattice on the substrate surface. It can be performed.
Moreover, it is preferable that the space | interval of the electrode which consists of said carbon material, and the said board | substrate shall be 100 micrometers-5 mm. In an electrode having a conventional insulating member, the effective distance between the electrodes is several times the actual inter-electrode distance (× 1/2 of the dielectric constant) because of the interposition of the insulating member. It is necessary to reduce the distance (for example, 2 mm or less). However, when using electrodes made of carbon material, it is possible to increase the distance between the electrodes compared to the electrode with the insulating member because the insulating member is not interposed. As a result, the in-plane uniformity of the plasma process is improved. can do. If the distance between the electrode made of the carbon material and the substrate is larger than 5 mm, it becomes difficult to maintain a stable discharge, and if it is smaller than 100 μm, the possibility that the electrode and the substrate are in contact with each other increases, so the above range of 100 μm to 5 mm. Is preferred.

  Here, the shape of the electrode made of the carbon material is not limited to a plate shape having a flat surface as shown in FIG. 1, but may be a shape as shown in FIGS.

  As shown in FIGS. 3 (a) to 3 (d), by reducing the area of the portion facing the surface of the substrate 6, the electric field generated by the high frequency power is formed concentrated on the tip, so that the discharge starts. There is an advantage that it becomes easy.

  3A is a cylindrical electrode 32A, FIG. 3B is a prismatic electrode 32B having a pentagonal cross section, FIG. 3C is a columnar electrode 32C having a pentagonal cross section, and FIG. This is a prismatic electrode 32D having a hexagonal cross section in which the ridge line at the lower end of the prismatic electrode 32B having a pentagonal cross section shown in FIG.

  Furthermore, when the electrodes are shaped as shown in FIGS. 4A to 4D, the area to be processed becomes small, but local processing becomes possible.

  4 (a) is a cylindrical electrode 42A, FIG. 4 (b) is an electrode 42B provided with a conical portion 42Bb at the lower end of the cylindrical main body 42Ba, and FIG. 4 (c) is a hemispherical shape at the lower end of the cylindrical main body. FIG. 4 (d) shows an electrode 42D in which a conical portion 42Db is provided at the lower end of a cylindrical main body 42Da, and the tip 42Dc of the conical portion is rounded.

  By using the electrode having the above shape, the electric field can be concentrated at the tip, and the voltage at the start of discharge can be lowered. Thereby, concentration of plasma at the start of discharge can be prevented, damage to the electrode can be suppressed, and contamination due to adhesion of fine particles of carbon material to the substrate surface can be prevented.

  Further, a commonly used PBN (pyrolytic boron nitride) coating, SiC (silicon carbide) coating, or the like may be applied to the surface of the electrode made of a carbon material. By performing these treatments, higher heat resistance and thermal shock resistance can be obtained. The film thickness of these coatings is usually on the order of several tens of μm, and does not greatly affect the stability of sustaining discharge. Further, as the carbon material used for the electrode, commonly used glassy carbon or carbon fiber may be used. Since these materials are not a texture of particles unlike conventional graphite, the electrode surface The generation of fine particles from can be suppressed.

  The process gas supply method is not limited to that shown in FIG. For example, FIG. 2 is a perspective view of an apparatus in which the shape of the gas supply unit is different from that of the plasma process apparatus of FIG. 1, and is a schematic view of the vicinity of the electrode 2 viewed from an oblique direction. As shown in FIG. 2, by providing the gas supply port 16 in the vicinity of the electrode 2, the process gas can be efficiently supplied to the plasma generation region.

  In the present invention, the internal pressure of the chamber 1 is most effective especially at atmospheric pressure. In the present invention, the preferred pressure range is 100 Torr to 2 atm. For example, 10 Torr to 5 atmospheres can be mentioned.

  Examples of compound semiconductors include III-V group compounds such as Si and InP, II-VI group compounds such as ZnSe, and nitride semiconductors such as GaN and AlN. Also included are ternary mixed crystals and quaternary mixed crystals such as AlGaN and AlGaNInN.

Further, as the halogen gas, the chlorine gas is used in the first embodiment, but the halogen gas is not necessarily limited thereto. Gases such as fluorine and fluorine compounds such as CF ₄ , chlorine compounds such as BCl ₃ , and bromine compounds may be used.

(Second Embodiment)
The second embodiment of the present invention relates to a plasma processing method for stably performing a plasma process.

  In the plasma process method of the second embodiment, the voltage at the start of discharge is managed, so that the change over time of the electrode 2 made of a carbon material can be managed, and a more stable plasma process can be performed. Is the method. In the plasma processing method according to the present invention, an electrode made of a carbon material causes only a chemical reaction with a process gas containing a halogen gas by generating plasma under a pressure near atmospheric pressure. Therefore, the consumption of the electrode made of carbon material is much smaller than when the plasma was generated in a low pressure atmosphere, but if it is discharged continuously for a long time, it will be consumed at the part in contact with the plasma. Was confirmed. In this case, the distance between the surface of the electrode 2 and the surface of the substrate 6 is increased, the impedance of the load of the system that generates plasma is increased, and the process result may change even when the same power is supplied.

  Therefore, by managing the voltage at the start of discharge, it is possible to manage the load impedance of the system that generates plasma, that is, the distance between the surface of the electrode 2 and the surface of the substrate 6. In other words, by controlling the distance between the surface of the electrode 2 and the surface of the substrate 6 so that the voltage at the start of discharge is always constant, the impedance of the system load that generates plasma can be made constant. The plasma process can be performed stably.

Here, the plasma processing method of the present invention will be described with reference to FIG. The distance of the gap between the electrode 2 and the substrate 6 in FIG. Under normal conditions, the distance d is set to 0.5 μm, plasma is generated in an atmospheric pressure atmosphere, and processing such as etching is performed. When plasma is generated under the conditions of He / Cl ₂ = 99.9 / 0.1% and 150 MHz high frequency power = 170 W, the voltage at the start of discharge is 5 at the beginning of using the electrode 2 made of carbon material. It was 0.1 kV. In the electrode 2 made of a carbon material, since plasma is generated in an atmospheric pressure atmosphere, physical ion collision is suppressed, and the electrode itself is consumed much more than when plasma is generated in a conventional low-pressure atmosphere. However, it was confirmed that the portion in contact with the plasma was consumed when a long discharge or a large number of discharge start operations were performed. In this case, the distance d between the electrode 2 and the substrate 6 was larger than that at the initial setting, and accordingly, the voltage at the start of discharge was as high as 5.3 kV. In this state, even if discharge is performed under the same plasma generation conditions, the plasma state changes and the process result also changes. Here, by generating the plasma by adjusting the distance d between the electrode 2 and the substrate 6 so that the voltage at the start of discharge becomes constant, the plasma state can be made constant at all times, and the result of the process Can also be stabilized.

  As described above, by performing the plasma process method shown in the second embodiment, it is possible to detect a change over time of an electrode made of a carbon material without requiring extensive modification of the apparatus or introduction of a measuring instrument. This makes it possible to continuously perform a stable plasma process.

(Third embodiment)
The third embodiment of the present invention is different from the apparatus of the plasma processing method shown in the first embodiment, and relates to the configuration of an electrode made of a carbon material.

  FIG. 5 is a cross-sectional view showing a plasma processing apparatus using the plasma processing method according to the present invention, and a part not related to the description of the third embodiment is partially omitted. FIG. 6 is an enlarged perspective view of the rotating electrode mechanism.

  The plasma process apparatus according to the third embodiment includes, in addition to the members made up of the plasma process apparatus according to the first embodiment, a rotating electrode 20, connecting portions 21, 25, an insulating member 22, a support member 23, and a rotating shaft. 24 and a motor 26 are mainly provided. The rotating electrode 20, the connecting portions 21 and 25, the insulating member 22, the support member 23, the rotating shaft 24 and the motor 26 constitute a rotating mechanism.

  The plasma process apparatus shown in the third embodiment is one in which the mechanism of the portion of the electrode 2 in FIG. 1 is changed. The electrode shown in the first embodiment is installed in the chamber 1 in a fixed state, but the electrode in the third embodiment is not installed in a fixed state and has a structure that can rotate. Installed. Below, a rotation mechanism is demonstrated.

  The rotating electrode 20 made of a carbon material is connected to the rotating shaft 24 in the connecting portion 21. The rotating electrode 20 and the rotating shaft 24 are supported by a connecting portion 21 having a bearing mechanism, and dust generation from the bearing mechanism into the chamber 1 is prevented by a magnetic fluid seal (not shown). The connection portion 21 is fixed to the support member 23 via the insulating member 22, and the support member 23 is further fixed to the chamber 1. Here, since the connection part 21 is being fixed via the insulating member 22, it is in the state which is not electrically grounded. The high frequency power is supplied from the power supply member 3 to the rotary electrode 20 via the connection portion 21. The rotating shaft 24 is connected to the motor 26 in the connecting portion 25, is supported by the connecting portion 25 having a bearing mechanism, and prevents dust generation from the bearing mechanism into the chamber 1 by a magnetic fluid seal (not shown). Yes.

  With the structure as described above, the rotating electrode 20 can be rotated by the motor 26, and at the same time, dust generation from the rotating mechanism into the chamber 1 can be prevented. By processing the surface of the substrate 6 by generating plasma while rotating the rotating electrode 20, the surface in contact with the rotating electrode and the plasma always changes, and a specific part is prevented from being heated locally. be able to. Thereby, the lifetime of an electrode can be extended and a maintenance cycle can be extended. In addition, the process gas supplied into the chamber 1 can be efficiently supplied to the plasma generation region by rotating the electrode.

  In addition, as a shape of a rotating electrode, the cylindrical thing as shown to Fig.3 (a) is preferable. This is because the electrodes with other shapes change the distance from the surface of the substrate 6 when rotated, and plasma is not stably generated. Further, the electrodes as shown in FIGS. 4A to 4D may be rotated about the vertical direction. In this case, by rotating the electrode around the vertical direction, the symmetry of the processed shape can be improved even when the electrode shape is not completely symmetrical. In addition, the gas flow around the electrode can always be reproduced in the same state, and the stability of the process can be improved. In this case, the plasma is always generated by a certain part of the electrode, but allows local processing.

FIG. 1 is a sectional view showing the structure of a plasma processing apparatus using the plasma processing method according to the first embodiment of the present invention. FIG. 2 is a perspective view of an apparatus in which the shape of the gas supply unit is different from that of the plasma process apparatus. FIG. 3 is a partially enlarged view of an electrode having a different form from the plasma processing apparatus. FIG. 4 is a partially enlarged view of an electrode having a different form from the plasma processing apparatus. FIG. 5 is a sectional view showing the structure of a plasma processing apparatus using the plasma processing method according to the third embodiment of the present invention. FIG. 6 is an enlarged perspective view of the rotating electrode mechanism of the plasma process apparatus. FIG. 7 is an enlarged view of the vicinity of an electrode of a conventional plasma processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Chamber 2 ... Electrode 3 ... Power supply member 4 ... Matching device 5 ... High frequency power supply 6 ... Substrate 7 ... Heater 8 ... XY stage 9 ... Bellows 10 ... Lifting mechanism 11 ... Gas supply part 12 ... Flow control device 13 ... Gas cylinder 14 DESCRIPTION OF SYMBOLS ... Exhaust pump 15 ... Plasma 16 ... Gas supply port 20 ... Rotary electrode 21, 25 ... Connection part 22 ... Insulating member 23 ... Support member 24 ... Rotating shaft 26 ... Motor

Claims (7)

A plasma process method for performing a plasma process on a substrate made of a compound semiconductor material disposed in the processing chamber by turning a process gas introduced into the processing chamber into a plasma state,
The process gas contains at least a halogen gas,
In the processing chamber and in a gas atmosphere containing at least the halogen gas under a pressure of 10 Torr to 5 atm, an electrode made of a carbon material and the substrate are arranged with a space therebetween,
Heating the substrate to a temperature equal to or higher than the boiling point of the compound of the halogen gas and the substrate material;
A plasma process method, wherein a surface of the substrate is processed by plasma generated between the electrode and the substrate by supplying high-frequency power to the electrode. The plasma processing method according to claim 1,
A plasma process method, wherein an interval between the electrode made of the carbon material and the substrate is set to 100 μm to 5 mm. The plasma processing method according to claim 1 or 2,
A plasma process method, comprising: managing a state of the electrode made of the carbon material based on a voltage at which discharge is started when high-frequency power is supplied to the electrode. The plasma processing method according to any one of claims 1 to 3,
A plasma process method, wherein plasma is generated between the electrode and the substrate in a state where the electrode is rotated by a rotating mechanism. A plasma process apparatus for performing a plasma process on a substrate made of a compound semiconductor material disposed in the processing chamber by turning the process gas introduced into the processing chamber into a plasma state,
The process gas contains at least a halogen gas,
An electrode made of a carbon material disposed at a distance from the substrate in the processing chamber;
A high frequency power supply unit for supplying high frequency power to the electrode;
A heating unit for heating the substrate so as to have a temperature equal to or higher than the boiling point of the compound of the halogen gas and the substrate material;
The substrate is heated by the heating unit so that the temperature is equal to or higher than the boiling point of the compound of the halogen gas and the substrate material in a gas atmosphere containing at least the halogen gas under a pressure of 10 Torr to 5 atm in the processing chamber. In addition, plasma is generated between the electrode and the substrate by supplying high-frequency power to the electrode from the high-frequency power supply unit, and the surface of the substrate is processed by the generated plasma. Plasma processing equipment. The plasma processing apparatus according to claim 5, wherein
A plasma process apparatus that manages a state of the electrode based on a voltage at which discharge is started when high-frequency power is supplied from the high-frequency power supply unit to the electrode. The plasma processing apparatus according to claim 5 or 6,
A rotation mechanism for rotating the electrode;
A plasma processing apparatus, wherein plasma is generated between the electrode and the substrate while the electrode is rotated by the rotating mechanism.

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