JP6351458B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus provided with a magnetic field coil.

  In recent years, in order to reduce the cost of semiconductor manufacturers, the design rule (design standard) for semiconductor products has been refined to increase the number of chips that can be taken from a single wafer. It is also being considered.

  For this reason, for example, in an etching apparatus which is one of plasma processing apparatuses, development of an apparatus corresponding to a wafer having a diameter of φ450 mm from a wafer having a diameter of φ300 mm has been started in order to increase the diameter of the wafer. Also in a microwave plasma etching apparatus having a magnetic field coil, development of an apparatus corresponding to a wafer having a diameter of φ450 mm has been started from an apparatus corresponding to a wafer having a diameter of φ300 mm.

  As the wafer diameter is increased, the magnetic field coil of the microwave plasma etching apparatus corresponding to a wafer having a diameter of 450 mm and the coil case covering the magnetic field coil are also larger than the etching apparatus corresponding to the wafer having a diameter of 300 mm.

  The coil case is configured to cover the magnetic field coil from the conventional microwave plasma etching apparatus, and can be formed so as to cover the magnetic field lines by the magnetic field coil, thereby reducing the leakage of the magnetic field from the coil case to the outer periphery. be able to.

  In order to generate high-density and uniform plasma in the plasma processing chamber and perform plasma processing at high speed and uniformly, in the microwave plasma processing apparatus equipped with a magnetic field coil, a slow wave circuit is provided in the plasma generation chamber and plasma processing is performed. Japanese Patent Application Laid-Open No. H10-228667 discloses a technique for generating an average minimal magnetic field in a chamber.

JP-A-6-084836

  The coil case can reduce the leakage of the magnetic field from the coil case to the outer periphery by covering the magnetic field coil, and since there has been a track record in a microwave plasma etching apparatus corresponding to a wafer having a diameter of φ300 mm, Tried to apply to the microwave plasma etching equipment corresponding to the wafer of φ450mm. However, it has been found that if the microwave plasma etching apparatus corresponding to a wafer having a diameter of 300 mm is replaced with a microwave plasma etching apparatus corresponding to a wafer having a diameter of 450 mm, the apparatus becomes too large. Therefore, a high-frequency power source, a DC power source, a matching unit, and the like are arranged on the coil case. As a result, the apparatus can be made compact. However, as a result of such a compact design, it has been found that in a microwave plasma etching apparatus compatible with a wafer having a diameter of φ450 mm, various power sources installed at the upper part of the coil case may fall during the etching process of the sample. did.

  A first object of the present invention is to provide a plasma processing apparatus that includes a coil case that covers a magnetic field coil and can be made compact even in a plasma processing apparatus that supports a wafer having a diameter of φ450 mm or more.

  A second object of the present invention is to provide a plasma processing apparatus capable of preventing various power sources installed on a coil case from dropping during sample processing even when the above-described compactness is achieved. There is to do.

As one embodiment for achieving the first object, a processing chamber in which a sample is subjected to plasma processing, an oscillator that oscillates microwaves, and power of the microwave is supplied to the processing chamber via a waveguide. A first high-frequency power source, a second high-frequency power source for supplying high-frequency power to a sample stage on which the sample is placed via a matching unit, and a DC voltage for electrostatically adsorbing the sample to the sample stage. In a plasma processing apparatus comprising a DC power source to be applied to the sample stage, and a magnetic field generating means for generating a magnetic field in the processing chamber,
The magnetic field generation means comprises a coil that generates a magnetic field and a cylindrical coil case that prevents the magnetic field generated by the coil from leaking out of the processing chamber,
The first high-frequency power source, the second high-frequency power source, the direct-current power source, and the matching unit are arranged above the coil case.

Further, as an embodiment for achieving the second object, in the plasma processing apparatus,
The first high-frequency power source is disposed closer to the waveguide than the second high-frequency power source, the DC power source, and the matching unit,
A shielding plate that shields a magnetic field is disposed between the first high-frequency power source and the waveguide.

  By arranging various power supplies and the like above the coil case, it is possible to provide a plasma processing apparatus that can be made compact.

  In addition, by arranging a shielding plate that shields the magnetic field between the waveguide and the first high-frequency power source closest to the waveguide, various power sources installed on the coil case can be used during sample processing. A plasma processing apparatus capable of suppressing falling can be provided.

1 is a schematic longitudinal sectional view of a plasma etching apparatus according to an embodiment of the present invention. 1 is a top view of a plasma etching apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view (CC line sectional drawing of FIG. 2) of the coil case vicinity in the plasma etching apparatus which concerns on the Example of this invention. It is a cross-sectional view near the coil case upper part in the plasma etching apparatus according to the embodiment of the present invention. It is a cross-sectional view of the vicinity of the central part of the coil case of the plasma etching apparatus according to the embodiment of the present invention. It is a top view of the other plasma etching apparatus which concerns on the Example of this invention. It is a principal part longitudinal cross-sectional view (DD line sectional drawing of FIG. 6) of the other plasma etching apparatus which concerns on the Example of this invention.

  The inventors have a coil case covering a magnetic field coil, and various power sources are arranged on the coil case. In a microwave plasma etching apparatus corresponding to a wafer having a diameter of 450 mm, various power sources installed on the coil case are samples. The cause of falling during the etching process was investigated. As a result, it was found that the circuit on the substrate inside various power supplies malfunctioned because the thickness of the coil case covering the magnetic field coil was the same as that of an etching apparatus corresponding to a wafer having a diameter of φ300 mm. In order to prevent this measure, that is, to suppress leakage of the magnetic field from the coil case, it is conceivable to increase the thickness of the coil case covering the enlarged magnetic field coil in an etching apparatus corresponding to a wafer having a diameter of φ450 mm. However, from the viewpoints of total weight limitation due to the increase in size, lack of technology for processing a thick coil case width, cost control, etc., the thickness of the coil case is the same as that of an etching apparatus corresponding to a wafer having a diameter of 300 mm. It is desirable to make it. In view of this, the inventors decided to install a shielding plate between various power sources installed on the coil case and the waveguide in the microwave plasma etching apparatus corresponding to a wafer having a diameter of φ450 mm. As a result, even for a microwave plasma etching apparatus that is compatible with wafers with a diameter of φ450 mm and is made compact, the magnetic field leaking from the coil case during the etching process is shielded and the influence on various power sources is reduced. The malfunction of the substrate inside the various power supplies installed on the top is suppressed, and the operation of the apparatus is stabilized.

  Hereinafter, the present invention will be described in detail with reference to examples. In the embodiment, a microwave plasma etching apparatus will be described, but the present invention is not limited to the etching apparatus. In the reference numerals shown in the drawings, the same reference numerals indicate the same elements.

  A plasma processing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view showing an ECR (Electoron Cyclotron Rezonance) microwave plasma etching apparatus used in this embodiment. A shower plate 105 (for example, made of quartz) and a dielectric window 106 (for example, made of quartz) for introducing a processing gas into the vacuum container 101 are installed and sealed on the upper part of the vacuum container 101 whose upper part is opened. A processing chamber 107 is formed. The shower plate 105 is provided with a plurality of holes for flowing a processing gas, and the gas supplied from the gas supply device 108 is introduced into the processing chamber 107 through the plurality of holes. Further, a vacuum exhaust device (not shown) is connected to the vacuum container 101 via a vacuum exhaust port 109.

  In order to transmit power for generating plasma to the processing chamber 107, a waveguide 110 for transmitting electromagnetic waves is provided above the dielectric window 106. The high frequency (high frequency for plasma generation) transmitted to the waveguide 110 is oscillated from the oscillator 103 under the control of the first high frequency power supply 104. Further, since the first high frequency power supply 104 includes a pulse oscillator, it can oscillate time-modulated intermittent high frequency or continuous high frequency.

  The frequency of the high frequency is not particularly limited, but in this embodiment, a 2.45 GHz microwave (high frequency for plasma generation) is used. A magnetic field generating coil 111 for forming a magnetic field is provided on the outer peripheral portion of the processing chamber 107, and the electric power oscillated from the oscillator 103 is formed into a high-density plasma in the processing chamber 107 by interaction with the formed magnetic field. Is generated. The magnetic field generating coil 111 is covered with a coil case 112.

  A sample stage 102 is provided below the vacuum vessel 101 so as to face the shower plate 105. The sample stage 102 has an electrode surface covered with a sprayed film (not shown), and a DC power source 117 is connected through a high frequency filter 116. Furthermore, a second high-frequency power source 115 that is a high-frequency power source for bias is connected to the sample stage 102 via a matching circuit (matching unit) 114. A temperature controller (not shown) is also connected to the sample stage 102.

  The wafer 113 is transferred to the processing chamber 107 of the vacuum vessel 101 by a transfer means (not shown) and placed on the sample stage 102. The wafer 113, which is a sample transported into the processing chamber 107, is adsorbed onto the sample stage 102 and temperature-controlled by an electrostatic force of a DC voltage applied from a DC power source 117. After a desired processing gas is supplied to the processing chamber 107 by the gas supply device 108, the inside of the vacuum vessel 101 is controlled to a predetermined pressure via the vacuum exhaust device, and a high frequency is supplied from the oscillator 103 into the processing chamber 107 for processing. Plasma is generated in the chamber 107. By applying high-frequency power from a second high-frequency power source 115 connected to the sample stage 102, ions are drawn from the plasma into the wafer, and the wafer 113 is subjected to plasma processing (etching). In addition, since the second high-frequency power source 115 includes a pulse oscillator, it is possible to apply time-modulated intermittent high-frequency power or continuous high-frequency power to the sample stage 102.

  In the plasma etching apparatus according to the present embodiment, as shown in FIG. 2, a DC power source 117 and a matching circuit 114, and a first high frequency power source 104 and a second high frequency power source 115 are provided in a waveguide above the coil case 112. 110 on both sides. The reason why various power sources are mounted on the coil case 112 in this way is to make an excessively large device compact, and because the arrangement of various power sources is also limited. In particular, the first high-frequency power source 104 and the matching circuit 114 having large outer dimensions as viewed from above are arranged near the center of the coil case 112 where a wide area can be secured, that is, near the waveguide 110. A small second high-frequency power source 115 and a DC power source 117 are arranged around the coil case 112, that is, further outside the first high-frequency power source 104 and the matching circuit 114. Further, by arranging the parts in the longitudinal direction parallel to the longitudinal direction of the waveguide 110, the space can be used effectively, and the parts can be arranged in a smaller space.

  Etching corresponding to a wafer having a diameter of 450 mm, in which a DC power source 117 and a matching circuit 114, and a first high-frequency power source 104 and a second high-frequency power source 115 are arranged on both sides of the waveguide 110 on the coil case 112. When the etching process was performed using the apparatus, it was found that the first high-frequency power supply 104 installed on the upper part of the coil case 112 was dropped during the etching process under specific conditions. One factor that causes the first high-frequency power supply 104 to drop is the operation of detecting overheating (detection at 80 ° C. or higher) of the substrate inside the first high-frequency power supply 104. If it is a normal overheat detection operation, it does not take time to recover the first high-frequency power supply 104, but it takes time to recover after the current overheat detection operation. Further, it was confirmed that if the etching process is performed again under specific conditions after the restoration of the first high-frequency power supply 104, the first high-frequency power supply 104 is turned off again. Therefore, the state of the overheat detector on the substrate inside the first high-frequency power source 104 was confirmed, but no discoloration of the overheat detector seen at the time of overheat detection was observed.

  Therefore, the conditions for performing the next etching process were confirmed. During the etching process, there is a condition that the first high-frequency power supply 104 does not drop. When the processing conditions are examined, it is found that the first high-frequency power supply 104 falls during the etching process depending on the use area of the magnetic field generating coil 111. . FIG. 3 shows a schematic enlarged cross-sectional view of the coil case 112 (CC line cross-sectional view of FIG. 2, shower plate etc. not shown). The magnetic field generating coil 111 installed inside the coil case 112 is divided into an upper coil 111a, an intermediate coil 111b, and a lower coil 111c. During the etching process, magnetic field lines 118 are formed from the lower coil 111c along the upper coil 111a, and are connected to the lower coil 111c through the processing chamber 107.

  At this time, the plasma can be diffused into the processing chamber 107 along the magnetic field lines 118 by adjusting the magnitude of the current of the lower coil 111c. Therefore, high-density and highly uniform plasma can be generated in the processing chamber 107, and the wafer 113 can be etched at high speed and uniformly.

  4 is a cross-sectional view taken along the line AA of the microwave plasma etching apparatus shown in FIG. 1, and is a cross-sectional view of the upper coil 111a and the coil case 112. FIG. The upper coil 111a is covered with a coil case 112 on the inside and outside. By covering the inner side of the upper coil 111 a with the coil case 112, the plasma can be guided into the processing chamber 107 along the magnetic field lines 118.

FIG. 5 shows a BB cross section of FIG. Since the inside of the middle coil 111 b is not covered with the coil case 112, the plasma can diffuse into the processing chamber 107 without being affected by the magnetic field lines 118. The lower coil 111c has the same structure as the middle coil 111b. (Not shown)
From this, as a factor that the first high frequency power supply 104 falls during the etching process, when the current of the lower coil 111c is increased, the magnetic field leaks from the coil case 112, and the malfunction of the substrate inside the first high frequency power supply 104 occurs. It was estimated that That is, the installation location of the first high-frequency power source 104 has a structure in which the direction of the substrate in the power source is closer to the waveguide 110 and is easily affected by the magnetic field lines 118 along the upper coil 111a. . Further, the lid covering the substrate inside the first high frequency power supply 104 is made of aluminum, and the magnetic field leaked from the magnetic field lines 118 in the coil case penetrates aluminum having a low relative permeability of 1. It was estimated that the malfunction of the board | substrate in the inside of the 1st high frequency power supply 104 was induced.

  As a countermeasure, it is conceivable to move the place where the first high-frequency power supply 104 is installed. However, the various power supplies are arranged so as not to protrude from the coil case 112 as much as possible, and external dimensions (in particular, It is difficult to change the installation location of the first high-frequency power supply having a large long side dimension.

  Therefore, the inventors installed a shielding plate 119 next to the first high-frequency power source 104 at the top of the coil case 112 as shown in FIG. As a result, leakage of the magnetic field could be suppressed even under specific conditions where the current of the lower coil 111c was increased. The shielding plate 119 is made of iron and has a higher magnetic permeability than aluminum having a low magnetic permeability. Therefore, even when a magnetic field leaks from the coil case 112, a magnetic field is generated inside the first high frequency power supply 104. It is thought that it does not reach.

  In general, there are aluminum and copper as materials having low magnetic permeability, and iron and SUS as materials having high magnetic permeability.

  The magnetic permeability is an index indicating how much the strength of the magnetic field exerts on the space, but aluminum is 1 and iron is 5000 in terms of relative magnetic permeability, which is a ratio to the vacuum magnetic permeability. When the relative magnetic permeability is low, the magnetic lines of force 118 penetrate the material, whereas when the relative magnetic permeability is high, the magnetic lines of force 118 can easily magnetize the material, thereby preventing the material from penetrating. There are three materials that are magnetized by the atoms themselves: iron (relative magnetic permeability 5000), nickel (relative magnetic permeability 600), and cobalt (relative magnetic permeability 250), all of which indicate that the magnetic field lines 118 penetrate the material. It is possible to suppress. That is, by using a material having a relative permeability exceeding 1, an effect as a shielding plate appears, and a material having a relative permeability in the range of 250 to 5000 is practical. Among them, iron is the most excellent material for the shielding plate in terms of cost and performance.

  FIG. 7 shows a state in which various power sources are installed on top of the coil case 112 (DD line cross-sectional view of FIG. 6, shower plate etc. not shown). It is the figure which looked at the waveguide 110 in the front, and since the space between the 1st high frequency power supply 104 and the waveguide 110 is narrow, the thin shielding board 119 was employ | adopted. In this example, the dimensions of the iron shielding plate 119 were 420 mm high, 620 mm wide, and 2 mm thick. The higher the relative permeability, the thinner the shielding plate. In addition, it is preferable to dispose the components arranged on the upper part of the coil case 112 as far as possible from the waveguide 110. The shielding plate can be attached not only to the first high-frequency power source 104 but also to other components.

  Using the ECR microwave etching apparatus having the configuration shown in FIGS. 1, 6, and 7, the wafer (sample) was etched under specific conditions in which the current of the lower coil 111c was increased. The malfunction of the substrate inside the first high frequency power supply 104 was suppressed, the operation of the apparatus was stabilized, and good etching could be performed stably. This is because the magnetic field leaked from the magnetic field lines 118 passing through the coil case 112 can be blocked from entering the first high-frequency power source 104 by the iron shielding plate 119.

  As described above, according to the present embodiment, it is possible to provide a plasma processing apparatus that includes a coil case that covers a magnetic field coil and can be made compact even if it is a plasma processing apparatus that supports a wafer having a diameter of 450 mm. In addition, even when the above-described compactness is achieved, it is possible to provide a plasma processing apparatus that can suppress various power supplies installed on the coil case from falling during sample processing.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. It is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

DESCRIPTION OF SYMBOLS 101 ... Vacuum container, 102 ... Sample stand, 103 ... Oscillator, 104 ... First high frequency power supply, 105 ... Shower plate, 106 ... Dielectric window, 107 ... Processing chamber, 108 ... Gas supply device, 109 ... Vacuum exhaust port, DESCRIPTION OF SYMBOLS 110 ... Waveguide, 111 ... Coil for magnetic field generation, 111a ... Upper coil, 111b ... Middle coil, 111c ... Lower coil, 112 ... Coil case, 113 ... Wafer, 114 ... Matching circuit (matching device), 115 ... Second High frequency power supply, 116... High frequency filter, 117... DC power supply, 118.

Claims (5)

A processing chamber in which a sample is plasma-processed, an oscillator that oscillates microwaves, a first high-frequency power source that supplies the microwave power to the processing chamber via a waveguide, and a high-frequency power that passes through a matching unit a second high frequency power source supplied to the sample stage which a sample is placed, a DC power source for applying a DC voltage to the sample stage for electrostatically adsorbing the sample to the sample stage, into the processing chamber In a plasma processing apparatus comprising a magnetic field forming means for forming a magnetic field ,
A shielding plate disposed between the first high-frequency power source and the waveguide to shield a magnetic field;
The magnetic field forming means comprises a coil case of the cylindrical preventing the coil is disposed within the magnetic field formed by the coil from leaking to the outside of the processing room,
The first high-frequency power source, the second high-frequency power source, the DC power source, the matching unit, and the shielding plate are arranged above the coil case ,
The plasma processing apparatus, wherein the first high-frequency power source is disposed closer to the waveguide than each of the second high-frequency power source, the DC power source, and the matching unit. The plasma processing apparatus according to claim 1,
The first high-frequency power source, the second high-frequency power source, the DC power source, and the matching unit in the plan view are parallel to the longitudinal direction of the waveguide in the plan view. Each of the high frequency power source, the second high frequency power source, the direct current power source, and the matching unit is disposed. In the plasma processing apparatus according to claim 1 or 2,
The shielding plate, Ri flat der,
The plasma processing apparatus, wherein the shielding plate is made of iron. In the plasma processing apparatus according to claim 1 or 2 ,
The plasma processing apparatus, wherein the shielding plate has a relative magnetic permeability in a range of 250 to 5000 . In the plasma processing apparatus according to any one of claims 1 to 4 ,
The plasma processing apparatus , wherein the sample is a wafer having a diameter of 450 mm or more .

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