JP6546041B2 - Plasma processing system - Google Patents

Description

  The present invention relates to a plasma processing apparatus.

  Plasma processing apparatuses are used for the production of semiconductor integrated circuit devices. The miniaturization of devices has progressed to improve device performance and reduce costs. Conventionally, two-dimensional miniaturization of elements increases the number of elements that can be manufactured from a single substrate to be processed and reduces the manufacturing cost per element, and at the same time improves performance by shortening the wiring length and the like. It has However, it is said that the limit of two-dimensional miniaturization is approaching, and measures such as the application of new materials and three-dimensional device structures are being made. Due to these structural changes, the level of difficulty in manufacturing is increased, and the increase in manufacturing costs has become a serious problem.

  Since a minute foreign matter or contaminant adheres to a semiconductor integrated circuit device in the process of being produced, it often causes fatal defects. Therefore, the semiconductor integrated circuit device is a clean room in which the temperature and humidity are optimally controlled by removing the foreign matter or contaminant. It is often manufactured in house. As the elements become finer, the cleanliness of the clean room required for manufacturing becomes higher, and enormous cost is required to construct and maintain such clean room. Therefore, efficient production using clean room space is required. From this point of view, miniaturization of semiconductor manufacturing apparatuses is strictly required.

  In a plasma processing apparatus for generating a plasma in a processing chamber inside a vacuum vessel to process a plate-like sample such as a semiconductor wafer, a technology for supplying a static magnetic field together with an electric field to the plasma processing chamber to form the plasma is widely used. It is done. This is because it is possible to suppress the loss of the plasma by the static magnetic field and to advantageously control the plasma distribution.

  Furthermore, by using the interaction between the electric field and the static magnetic field, there is an effect that generation is possible even under operating conditions where it is usually difficult to generate plasma. In particular, when a microwave is used as an electromagnetic wave for plasma generation and a static magnetic field is used to match the period of the electron's cyclotron motion and the frequency of the microwave, electron cyclotron resonance (hereinafter referred to as ECR) phenomenon may occur. Are known.

  Further, the wavelength of the plasma generating electromagnetic wave in the plasma can be adjusted by the static magnetic field, and the electromagnetic wave is introduced into the plasma processing chamber using an antenna adjusted to the wavelength and the static magnetic field is supplied to generate plasma efficiently by helicon wave. Are conventionally known. As an example of such a technique, the thing of an indication is known by Unexamined-Japanese-Patent No. 10-261631 (patent document 1). In this prior art, an antenna for helicon wave excitation is disposed between the coil forming the static magnetic field and the plasma generation container, and the coil is also disposed around the processing chamber below the plasma generation container. The configuration is disclosed.

Unexamined-Japanese-Patent No. 10-261631 gazette

  In the above-mentioned prior art, problems have occurred because the following points are not sufficiently considered.

  That is, in the plasma processing apparatus, the temperature of the inner wall surface of the processing chamber facing the plasma is an important parameter of the processing, and should be controlled to a value suitable for obtaining the desired processing shape as a result of the processing. desirable. On the contrary, if the temperature of the inner wall surface of the processing chamber is not within the appropriate range, for example, reaction products generated in the processing chamber during the etching process may adhere and accumulate, contaminating the sample or the inner wall surface. The interaction may adversely affect processing such as etching of the sample surface.

  However, in order to adjust the temperature of the surface of the member constituting the processing chamber to a value within a desired range, it is necessary to mount or install a device for temperature control on the member. This further complicates the configuration of the plasma processing apparatus, increases the installation area of the apparatus, and increases the manufacturing cost. Furthermore, since the plasma processing apparatus using a static magnetic field to form a plasma is provided with means for generating the static magnetic field, the structure of the apparatus becomes more complicated, and the installation area and volume of the apparatus become larger. There is a risk of

  An object of the present invention is to provide a plasma processing apparatus capable of reducing the installation area. Still another object is to provide a plasma processing apparatus with a simplified configuration.

In order to achieve the above object, according to the present invention, a plasma processing apparatus includes a processing chamber disposed inside a vacuum vessel and in which a plasma is formed inside under reduced pressure, and a wafer disposed in the processing chamber and processed by plasma A sample table on which the sample is placed, a means for forming an electric field supplied to form a plasma in the processing chamber, and an outer periphery of the processing chamber, which is disposed integrally with the processing chamber and supplied with power. a magnet for generating a static magnetic field to form a plasma Te was constructed and a regulator for adjusting the temperature of the magnet and the processing chamber based voltage of the power, the resistance value of the current or the magnet.

In order to achieve the above object, the present invention, a plasma processing apparatus, a processing chamber for inside the plasma which is disposed within the vacuum of the vacuum chamber is formed by being disposed in processing chamber flop plasma a sample stage on which a target substrate is mounted to be processed, means for forming an electric field which is supplied to form a flop plasma in processing chamber, integrated into processing chamber so as to surround the periphery of the treatment chamber An electromagnet arranged to form a static magnetic field and a mechanism for cooling the electromagnet are provided, and the temperature of the processing chamber is adjusted by the heating from the electromagnet or the cooling from the mechanism for cooling.

  According to the present invention, it is possible to provide a plasma processing apparatus capable of reducing the installation area. In addition, a plasma processing apparatus with a simplified configuration can be provided.

It is a longitudinal cross-sectional view which shows the outline of a structure of the microwave plasma etching apparatus which concerns on the Example of this invention. It is a longitudinal cross-sectional view which shows the electromagnet integrated with the plasma processing chamber in the microwave plasma etching apparatus shown in FIG. It is a graph which shows the temperature dependence of the resistivity of the coil in the electromagnet shown in FIG.

  The inventors examined the above-mentioned problems, and decided to integrally form the plasma processing chamber and the static magnetic field generator. This makes it possible to miniaturize and reduce the installation area. In addition, the temperature was calculated from the state of the static magnetic field generator to estimate the temperature of the plasma processing chamber. The mechanism for heating or cooling the plasma processing chamber can be controlled by the estimated temperature to control the plasma processing chamber to a desired temperature. By controlling the temperature of the plasma processing chamber with the static magnetic field generator, installation of a new temperature control mechanism is not required, and simplification of the system can be achieved.

  Next, a method of calculating the temperature from the state of the static magnetic field generator and estimating the temperature of the plasma processing chamber will be described. There is an electromagnet as a generator of static magnetic field. The static magnetic field generated by the electromagnet can be controlled to a predetermined intensity by the current value supplied to the electromagnet. The resistance value of the conducting wire used for the electromagnet is correlated with the temperature, and the resistance value of the conducting wire can be obtained by measuring the voltage generated in the electromagnet and dividing by the current value. The temperature can be calculated from the resistance value of the conducting wire. Further, the processing chamber can be heated by the power consumed by the electromagnet. Providing a cooling mechanism to the electromagnet and controlling the amount of heat release of the cooling mechanism using the temperature of the electromagnet determined by the method described above to control the electromagnet and the plasma processing chamber integrated with the electromagnet to a predetermined temperature it can.

  By integrally forming the plasma processing chamber and the static magnetic field generator, the plasma processing apparatus can be miniaturized. Further, since the temperature control mechanism can be simplified by estimating the temperature of the plasma processing chamber from the state of the static magnetic field generator, temperature control can be performed at low cost. Furthermore, since the generator of the static magnetic field is miniaturized, the static magnetic field generator can be disposed at a location where it has been difficult to install due to interference with other parts conventionally, and the effect of increasing the degree of freedom of static magnetic field distribution is realized. is there.

  Hereinafter, the present invention will be described by way of examples with reference to the drawings. In the embodiment, a microwave plasma etching apparatus is described as an example of a plasma processing apparatus, but the present invention is not limited to this apparatus, and in a plasma processing apparatus that generates plasma by electromagnetic waves, a static magnetic field is added to a plasma processing chamber The present invention is applicable to a plasma processing apparatus that utilizes the interaction of an electromagnetic wave and plasma with a static magnetic field.

  A microwave plasma etching apparatus will be described as an example of a plasma processing apparatus according to an embodiment of the present invention with reference to FIGS. 1 to 3. FIG. 1 is a longitudinal sectional view showing an outline of the configuration of a microwave plasma etching apparatus according to the present embodiment.

  The microwaves generated by the microwave source 101 are transmitted using the rectangular waveguide 103 and transmitted to the circular waveguide 105 by the rectangular circular waveguide converter 104. The rectangular circular waveguide converter 104 achieves miniaturization of the device by also serving as a corner that bends the direction of the waveguide by 90 degrees.

  The load impedance can be adjusted by the automatic matching unit 102 to automatically suppress the reflected microwaves generated by the microwave source 101. A magnetron with an oscillation frequency of 2.45 GHz was used as the microwave source. An isolator 118 was used for microwave source protection to prevent reflected waves from entering the microwave source.

  The circular waveguide 105 is connected to the cavity 106. The circular waveguide 105 has a diameter capable of propagating only the TE11 mode which is the lowest order mode. This has the effect of stabilizing the electromagnetic field of the microwave since no other propagation mode is mixed.

  The circular waveguide 105 has a generation mechanism of circular polarization (not shown), and has a function of converting microwaves incident as linear polarization into circular polarization. In the present embodiment, a phase plate made of quartz was used as a generation mechanism of circular polarization.

  The cavity 106 functions to adjust the microwave electromagnetic field distribution to a distribution suitable for plasma processing. A plasma processing chamber 110 is located below the cavity 106 via a microwave introduction window 107 and a shower plate 108. Since the shower plate 108 is directly exposed to the plasma generated in the plasma processing chamber 110, it is desirable that the material has high plasma resistance and does not adversely affect the plasma processing. Moreover, as a material of the microwave introduction window 107 and the shower plate 108, a material which efficiently transmits the microwave is desirable, and in the present embodiment, quartz was used.

  A minute gap (not shown) is provided between the microwave introduction window 107 and the shower plate 108, and a predetermined gas is supplied from a processing gas supply system 109 used for plasma processing. The shower plate 108 is provided with a plurality of fine gas supply holes (not shown), and supplies the processing gas supplied from the gas supply system 109 to the plasma processing chamber 110 in a shower shape.

  In the plasma processing chamber 110, a cylindrical substrate electrode 112 which is a sample stand for placing the processing substrate 111 is installed. An RF bias power supply 114 is connected to the substrate electrode 112 via an automatic matching unit 113 in order to supply RF bias power to the processing substrate 111. The frequency of the RF bias power supply was 400 kHz. In addition, a Si wafer with a diameter of 300 mm was used as a target substrate 111 such as a semiconductor wafer.

  A static magnetic field generator 119 for applying a static magnetic field in the plasma processing chamber 110 is provided. The static magnetic field generator 119 is composed of multistage electromagnets and magnetic materials. A magnetic material was used to prevent unnecessary magnetic field leakage to the outside, and magnetic lines were concentrated in the processing chamber to apply a magnetic field efficiently. By controlling the current supplied to each electromagnet using multistage electromagnets, the static magnetic field distribution in the plasma processing chamber can be easily adjusted. The plasma processing chamber corresponds to the circular shape of the substrate to be processed 111 and is configured to be approximately axially symmetrical. The static magnetic field generator was arranged to apply a static magnetic field parallel to the central axis of the plasma processing chamber.

  It is known that electrons moving in a static magnetic field undergo cyclotron motion under Lorentz force. It is known that an electron cyclotron resonance (ECR) phenomenon occurs where the microwave power is resonantly absorbed by electrons when the frequency of the microwave and the frequency of the cyclotron motion are matched.

  By using an ECR phenomenon generated by supplying a magnetic field with such an electric field, conditions under which plasma can be generated can be broadened. For example, when the microwave frequency is 2.45 GHz, ECR can be generated with a static magnetic field of 0.0875 Tesla. There is an effect that plasma is easily generated by ECR even at a low pressure which normally prevents generation of plasma. In addition, since plasma is mainly generated in the region where ECR occurs, the plasma generation region can be controlled by adjusting the distribution of the static magnetic field, and the controllability of plasma can be enhanced. Furthermore, since the diffusion of plasma is suppressed in the direction perpendicular to the static magnetic field, the plasma distribution can be optimally controlled by adjusting the static magnetic field.

  An evacuation system 117 is connected to the plasma processing chamber 110 via a valve 115 and a pressure control mechanism 116. Further, a pressure gauge (not shown) for measuring the pressure in the processing chamber is connected to the plasma processing chamber 110.

  The exhaust speed of the vacuum exhaust system 117 can be adjusted by the pressure control mechanism 116 and the pressure gauge. The pressure in the plasma processing chamber 110 can be controlled by controlling the exhaust speed of the processing gas supplied from the processing gas supply system 109.

  In the microwave plasma etching apparatus shown in FIG. 1, in this embodiment, the vacuum exhaust system etc. is installed eccentrically from the central axis of the apparatus, but in consideration of the axial symmetry of the gas flow in the plasma processing chamber, the central axis It may be placed on top. Although the apparatus configuration is complicated, it has the effect of enhancing the axial symmetry of the gas flow in the processing chamber.

  An inner cylinder 120 is provided to protect the inner wall of the plasma processing chamber 110 from plasma damage. As a material of the inner cylinder 120, it is desirable not to adversely affect the plasma processing, and in the present embodiment, quartz was used. A ground electrode 121 is provided at the lower part of the inner cylinder 120. Acts as the ground for the aforementioned RF bias supply.

  The inner surface not protected by the inner cylinder 120 of the plasma processing chamber 110 is protected by coating with a material that is not easily scraped by plasma. In this example, yttrium oxide was coated by thermal spraying.

  A transport path 122 for transporting the substrate to be processed 111 onto the substrate electrode (sample table) 112 is connected to the plasma processing chamber 110. The plasma processing chamber is normally maintained in a reduced pressure atmosphere, but a loader, an unloader, and a transfer mechanism (not shown) enable loading and unloading of the substrate while maintaining the reduced pressure atmosphere in the plasma processing chamber.

  In addition, a gate valve 123 which shuts off the plasma processing chamber 110 and the transfer path 122 is driven by the gate valve driving mechanism 124. Basically, the plasma processing chamber is shut off from the transfer path by the gate valve, except when loading and unloading the substrate to be processed, so that contamination from the outside or contamination from the plasma processing chamber can result in reaction products or processing. The reactive gas used is prevented from leaking to other places in the apparatus.

  An electromagnet 125 is disposed under the plasma processing chamber 110 and above the upper surface of the substrate electrode 112 on which the substrate 111 of the substrate electrode 112 is mounted or below the transport path 122, and at least a part of the outer peripheral wall of the container constituting the plasma processing chamber 110. Are embedded and in thermal contact with and integrated with the plasma processing chamber 110. Many mechanisms such as the gate valve driving mechanism 124 and the vacuum evacuation system and the RF bias power source related to the substrate electrode are installed near the electromagnet 125, and there is little space where the electromagnet 125 can be installed. By integrating with the processing chamber, the electromagnet 125 can be installed without interference with other mechanisms. In addition, if it is only a viewpoint of size reduction, as a magnet, it is not limited to an electromagnet.

  The method of obtaining the temperature of the electromagnet from the value of the current supplied to the electromagnet and the voltage value at that time will be described below. In order to obtain a desired static magnetic field, a predetermined direct current is applied to the electromagnet. Measure the DC voltage value between the electromagnet terminals at that time. The value obtained by dividing the DC voltage value by the DC current value is the resistance value R of the electromagnet. The resistance value R of the electromagnet is represented by the cross-sectional area S of the wire, the length L, and the resistivity ρ, as shown in equation (1). Since the cross-sectional area S and the length L of the wire are known, the resistivity ρ can be obtained from the obtained resistance value.

R = ρ × L / S (1)
R: Resistance value of the electromagnet [Ω]
ρ: Resistivity of wire of electromagnet [Ω · m]
L: Magnet wire length [m]
S: Cross section of wire rod of electromagnet [m ² ]
The resistivity ρ is known to have temperature characteristics specific to the material. The temperature dependency of the resistivity 性 in the case of copper is illustrated in FIG.

  It is possible to calculate the temperature by storing the temperature characteristics of the used wire and comparing it with the measured resistivity ρ. Since the resistivity ρ changes substantially linearly with temperature, the temperature may be determined by linear approximation. When it is desired to obtain with higher accuracy or when the temperature dependency of resistivity deviates from a straight line, the temperature may be determined by storing numerical values in a table and performing interpolation such as spline curve.

  The wire material of the electromagnet is preferably made of a material having a low resistivity from the viewpoint of power loss reduction, and copper was used in this embodiment.

  The electromagnet 125 will be described in detail with reference to FIG. The electromagnet 125 is a cylindrical component that constitutes the lower part of the plasma processing chamber 110. The upper and lower surfaces of the cylinder are vacuum sealable. In this example, vacuum sealing was performed by an O-ring. The wire 202 is wound directly on a member 201 for winding the wire of the electromagnet.

  A refrigerant flow path 203 for flowing the refrigerant is provided in the member 201, and the heat generated by energizing the electromagnet can be discharged. In the present embodiment, a copper plate 0.2 mm thick and 20 mm wide was used as the wire rod 202 of the electromagnet.

  A highly heat resistant polyimide sheet was sandwiched for insulation between the wires. The material of the member 201 was an aluminum alloy, and the inner side of the processing chamber was coated with yttrium oxide as described above.

  A resin having a high thermal conductivity and a high electrical insulation property was impregnated between the wire 202 and the member 201. Thus, the heat generated in the wire 202 can be efficiently discharged from the refrigerant flow path 203. An epoxy resin was used in this example as the resin to be impregnated.

  A controller for the flow rate of the refrigerant (not shown) is connected to the refrigerant flow path 203, and the flow rate of the refrigerant is adjusted in order to control the processing chamber temperature obtained from the current voltage of the electromagnet to a desired value. By adjustment, the temperature of the processing chamber integrated with the electromagnet can be controlled to a predetermined value. It goes without saying that the temperature of the electromagnet is controlled by adjusting the flow rate of the refrigerant.

  In the static magnetic field generator 119 installed at the upper portion of the processing chamber, the electromagnet 125 is disposed below the opening of the transfer path 122 or below the upper surface of the sample table (substrate electrode) 112 so as to surround the processing chamber. It becomes possible to control the magnetic field in the vicinity of the substrate to be processed which is difficult, and to control the plasma generation region in the vicinity of the substrate to be processed. In addition, by arranging the temperature-controlled electromagnet 125 below the opening of the transport path 122 or below the upper surface of the sample table 112 to surround the processing chamber, the temperature around the sample table becomes stable, and the temperature of the sample table itself Controllability is improved. In addition, since the inner wall of the processing chamber around the opening of the transfer path 122 or around the sample table is heated, reaction products are less likely to adhere, and foreign matter generation sources around the opening of the transfer path 122 and near the sample table can be reduced. it can.

  In this embodiment, an example in which the multistage electromagnet (static magnetic field generator) 119 is not integrated with the plasma processing chamber 110 has been described, but part or all of the electromagnets (static magnetic field generator) may be integrated.

  As described above, according to the present embodiment, it is possible to provide a plasma processing apparatus capable of reducing the installation area. In addition, a plasma processing apparatus with a simplified configuration can be provided.

  The present invention is not limited to the embodiments described above, but includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. It is also possible to replace part of one configuration with another.

DESCRIPTION OF SYMBOLS 101 ... Microwave source, 102 ... Automatic matching machine, 103 ... Rectangular waveguide, 104 ... Rectangular circular waveguide converter, 105 ... Circular waveguide, 106 ... Cavity part, 107 ... Microwave introduction window, 108 ... Shower Plate: 109: processing gas supply system 110: plasma processing chamber 111: substrate to be processed 112: substrate electrode (sample table) 113: automatic alignment unit 114: RF bias power supply 115: valve 116: pressure Control mechanism, 117: Vacuum evacuation system, 118: Isolator, 119: Static magnetic field generator, 120: Inner cylinder, 121: Ground electrode, 122: Substrate transport path for processing, 123: Gate valve, 124: Gate valve drive mechanism, 125: treatment chamber integrated electromagnet, 201: member, 202: wire rod, 203: refrigerant flow path.

Claims (7)

A processing chamber disposed inside the vacuum vessel and in which the plasma is formed inside under reduced pressure;
A sample stage disposed in the processing chamber and on which a wafer to be processed by the plasma is placed;
Means for forming an electric field supplied to form the plasma in the processing chamber;
A magnet which is disposed around the periphery of the processing chamber and is integrally formed with the processing chamber and is supplied with electric power to form a static magnetic field for forming the plasma;
A regulator that regulates the temperature of the magnet and the processing chamber based on the voltage of the electric power, the current, or the resistance value of the magnet;
A plasma processing apparatus comprising: The plasma processing apparatus according to claim 1,
The magnet is disposed in the vacuum vessel and connected to the vacuum vessel, and is disposed below the opening of the transfer path through which the wafer is transported inside or below the upper surface of the sample table in the process chamber and surrounding the process chamber. A plasma processing apparatus characterized by The plasma processing apparatus according to claim 1 or 2, wherein
A plasma processing apparatus, comprising: another magnet disposed around the upper or side periphery of the processing chamber to form a magnetic field for forming the plasma. The plasma processing apparatus according to any one of claims 1 to 3, wherein
The plasma processing apparatus, wherein the electric field is of microwave. A processing chamber disposed inside the vacuum vessel and in which the plasma is formed inside under reduced pressure;
A sample stage disposed in the processing chamber and on which a target substrate to be processed by the plasma is placed;
Means for forming an electric field supplied to form the plasma in the processing chamber;
An electromagnet disposed integrally with the processing chamber so as to surround the outer periphery of the processing chamber to form a static magnetic field ;
A mechanism for cooling this electromagnet and
And controlling the temperature of the processing chamber by heating from the electromagnet or cooling from the cooling mechanism . The plasma processing apparatus according to claim 5, wherein
The plasma processing apparatus, further comprising: a controller that adjusts the temperature of the processing chamber using a resistance value of a coil forming the electromagnet. The plasma processing apparatus according to claim 5 or 6, wherein
The plasma processing apparatus according to claim 1, wherein the electromagnet is disposed below an upper surface of the sample stage.

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