JP6479550B2 - Plasma processing equipment - Google Patents

Description

  Various aspects and embodiments of the present invention relate to a plasma processing apparatus.

  There is known a microwave plasma processing apparatus that processes a substrate to be processed using high-density plasma excited by microwaves. The microwave plasma processing apparatus can generate a uniform microwave in the processing apparatus by, for example, radiating the microwave into the processing apparatus using a flat antenna in which a large number of slots are arranged. Thereby, the microwave plasma processing apparatus can ionize the gas supplied in the processing apparatus and generate more uniform high-density plasma.

  A dielectric window formed of a dielectric is provided on the lower surface of the antenna. Ribs are formed on the dielectric window to ensure mechanical strength.

JP2015-18686A

  By the way, in the microwave plasma apparatus, in order to improve the film quality of the substrate to be processed, it is conceivable that the temperature of the substrate to be processed is set high or the distance between the antenna and the substrate to be processed is shortened. . However, if the temperature of the substrate to be processed is set high, the underlying layer may be damaged by heat. Therefore, it has been studied to improve the film quality of the substrate to be processed by shortening the distance between the antenna and the substrate to be processed. However, in the above microwave plasma apparatus, since the rib is formed on the lower surface of the dielectric window, it is difficult to shorten the distance between the antenna and the substrate to be processed.

  A plasma processing apparatus according to one aspect of the present invention is a plasma processing apparatus that processes a substrate to be processed in a processing container using microwave plasma, and includes a mounting table and an antenna. The mounting table is provided in the processing container and mounts a substrate to be processed. The antenna is provided above the mounting table so as to face the mounting table, has a dielectric plate, and is supplied into the processing container by radiating microwaves into the processing container through the dielectric plate. A plasma of a processing gas is generated. The dielectric plate is provided on the lower surface of the antenna, and is formed on at least a flat plate portion where the surface facing the mounting table is formed in a flat shape, and a surface opposite to the surface facing the mounting table in the flat plate portion. Rib.

  According to various aspects and embodiments of the present invention, the distance between the antenna and the substrate to be processed can be shortened while ensuring the mechanical strength of the antenna.

FIG. 1 is a top view schematically showing a plasma processing apparatus. FIG. 2 is a plan view showing a state in which the upper portion of the processing container is removed from the plasma processing apparatus shown in FIG. 3 is a cross-sectional view taken along the line AA of the plasma processing apparatus in FIGS. 1 and 2. 4 is an enlarged cross-sectional view of a portion on the left side of the axis X toward FIG. FIG. 5 is an enlarged cross-sectional view of a portion on the right side of the axis X toward FIG. FIG. 6 is a plan view showing an example of a schematic shape of the top board. FIG. 7 is a plan view showing an example of a schematic shape of the top board. FIG. 8 is a plan view showing an example of a schematic shape of the slot plate. FIG. 9 is a plan view showing an example of a schematic shape of the slow wave plate. FIG. 10 is a diagram illustrating an example of a simulation result of the first principal stress of the top plate on which no rib is provided. FIG. 11 is a diagram illustrating the height and width of the rib. FIG. 12 is a diagram illustrating an example of a simulation result of a top plate provided with ribs. FIG. 13 is an enlarged cross-sectional view showing another example of the antenna.

  In one embodiment, the disclosed plasma processing apparatus is a plasma processing apparatus that processes a substrate to be processed in a processing container using microwave plasma, and includes a mounting table and an antenna. The mounting table is provided in the processing container and mounts a substrate to be processed. The antenna is provided above the mounting table so as to face the mounting table, has a dielectric plate, and is supplied into the processing container by radiating microwaves into the processing container through the dielectric plate. A plasma of a processing gas is generated. The dielectric plate is provided on the lower surface of the antenna, and is formed on at least a flat plate portion where the surface facing the mounting table is formed in a flat shape, and a surface opposite to the surface facing the mounting table in the flat plate portion. Rib.

  Further, in one embodiment of the disclosed plasma processing apparatus, the antenna includes a conductor plate that is provided so as to be in contact with a surface opposite to the surface facing the mounting table in the flat plate portion, and that propagates microwaves. Alternatively, the rib may be formed in a region where the conductive plate is not provided in the surface opposite to the surface facing the mounting table in the flat plate portion.

  Further, in one embodiment of the disclosed plasma processing apparatus, the rib is formed along the peripheral edge of the surface opposite to the surface facing the mounting table in the flat plate portion so as to protrude upward from the flat plate portion. May be.

  In one embodiment of the disclosed plasma processing apparatus, the rib may be provided on the flat plate portion over the entire periphery of the surface on the opposite side of the surface facing the mounting table in the flat plate portion. Good.

  In one embodiment of the disclosed plasma processing apparatus, the thickness of the flat plate portion may be in the range of λ / 8 to 3λ / 8, where λ is the wavelength of the microwave in the dielectric plate. Good.

  Moreover, in one embodiment of the disclosed plasma processing apparatus, the height of the rib from the flat plate portion may be in a range of 2 to 4 times the thickness of the flat plate portion.

  In one embodiment of the disclosed plasma processing apparatus, the thickness of the rib may be in the range of 1 to 1.5 times the thickness of the flat plate portion.

  Further, in one embodiment of the disclosed plasma processing apparatus, the flat plate portion may be provided with a predetermined coating on a planar surface on the side facing the mounting table.

  Further, in one embodiment of the disclosed plasma processing apparatus, the distance between the lower surface of the flat plate portion and the substrate to be processed placed on the mounting table is within a range of 3 to 4 times the thickness of the flat plate portion. Also good.

  In one embodiment of the disclosed plasma processing apparatus, the dielectric plate may be formed of alumina, quartz, aluminum nitride, silicon nitride, or yttrium oxide.

  In one embodiment of the disclosed plasma processing apparatus, the mounting table may be provided to be rotatable about the axis so that the substrate to be processed moves around the axis. Further, the processing container may be divided into a plurality of regions in the circumferential direction in which the substrate to be processed moves with respect to the axis line by the rotation of the mounting table. The antenna may generate plasma of the processing gas supplied into the processing container by radiating microwaves into the processing container in one of the plurality of regions.

  Further, in one embodiment of the disclosed plasma processing apparatus, the antenna may have a substantially equilateral triangular cross section when viewed from a direction along the axis.

  Hereinafter, embodiments of the disclosed plasma processing apparatus will be described in detail with reference to the drawings. In addition, the invention disclosed by this embodiment is not limited. In addition, the embodiments can be appropriately combined within a range that does not contradict processing contents.

(Embodiment)
[Plasma processing apparatus 10]
FIG. 1 is a top view schematically showing the plasma processing apparatus 10. FIG. 2 is a plan view showing a state in which the upper member 12b of the processing container 12 is removed from the plasma processing apparatus 10 shown in FIG. FIG. 3 is a cross-sectional view of the plasma processing apparatus 10 taken along the line AA in FIGS. 1 and 2. 4 is an enlarged cross-sectional view of a portion on the left side of the axis X toward FIG. FIG. 5 is an enlarged cross-sectional view of a portion on the right side of the axis X toward FIG. The plasma processing apparatus 10 shown in FIGS. 1 to 5 mainly includes a processing container 12, a mounting table 14, a first gas supply unit 16, an exhaust unit 18, a second gas supply unit 20, and a plasma generation unit 22. Prepare. The plasma processing apparatus 10 in this embodiment is a semi-batch type substrate processing apparatus, for example.

  For example, as shown in FIG. 1, the processing container 12 is a substantially cylindrical container having an axis X as a central axis. The processing container 12 includes a processing chamber C therein. The processing chamber C includes a unit U that includes an injection unit 16a. The processing container 12 is formed of a metal such as Al (aluminum) whose inner surface is subjected to plasma-resistant processing such as alumite processing or Y2O3 (yttrium oxide) thermal spraying. The plasma processing apparatus 10 includes a plurality of plasma generation units 22 in the processing container 12. Each plasma generation unit 22 includes an antenna 22 a that outputs a microwave above the processing container 12. The plasma processing apparatus 10 illustrated in FIGS. 1 and 2 is provided with, for example, three antennas 22a. However, the number of antennas 22a provided in the plasma processing apparatus 10 is limited to that illustrated in FIGS. However, it may be changed as appropriate.

  As shown in FIG. 2, for example, the plasma processing apparatus 10 includes a mounting table 14 having a plurality of mounting regions 14a on the upper surface. The mounting table 14 is a substantially disk-shaped member having the axis X as the central axis. On the upper surface of the mounting table 14, a plurality of mounting regions 14 a (five in the example of FIG. 2) are formed concentrically about the axis X, on which a substrate W, which is an example of a substrate to be processed, is mounted. The substrate W is disposed in the placement region 14a, and the placement region 14a supports the substrate W so that the substrate W does not shift when the placement table 14 rotates. The placement region 14 a is a substantially circular recess having substantially the same shape as the substantially circular substrate W. The diameter W1 of the concave portion of the placement region 14a is substantially the same as the diameter of the substrate W placed on the placement region 14a. That is, the diameter W1 of the concave portion of the placement region 14a is such that the substrate W does not move from the fitting position due to centrifugal force even when the placed substrate W is fitted in the concave portion and the placement table 14 rotates. What is necessary is just to fix W.

  The plasma processing apparatus 10 includes a gate valve G on the outer edge of the processing container 12 for loading the substrate W into the processing chamber C and unloading the substrate W from the processing chamber C via a transfer device such as a robot arm. In addition, the plasma processing apparatus 10 includes an exhaust port 22 h below the outer edge of the mounting table 14. An exhaust device 52 is connected to the exhaust port 22h. The plasma processing apparatus 10 controls the operation of the exhaust device 52 to maintain the pressure in the processing chamber C at a target pressure. In the present embodiment, the pressure in the processing chamber C is set within a range of 1 to 5 Torr, for example.

  For example, as shown in FIG. 3, the processing container 12 includes a lower member 12a and an upper member 12b. The lower member 12a has a substantially cylindrical shape opened upward, and forms a recess including a side wall and a bottom wall forming the processing chamber C. The upper member 12b is a lid that has a substantially cylindrical shape and forms the processing chamber C by closing the upper opening of the concave portion of the lower member 12a. An elastic sealing member for sealing the processing chamber C, such as an O-ring, may be provided on the outer peripheral portion between the lower member 12a and the upper member 12b.

  The plasma processing apparatus 10 includes a mounting table 14 inside a processing chamber C formed by the processing container 12. The mounting table 14 is rotationally driven about the axis X by the drive mechanism 24. The drive mechanism 24 includes a drive device 24 a such as a motor and a rotary shaft 24 b and is attached to the lower member 12 a of the processing container 12.

  The rotating shaft 24b extends to the inside of the processing chamber C with the axis X as the central axis. The rotating shaft 24b rotates around the axis X by the driving force transmitted from the driving device 24a. The center of the mounting table 14 is supported by the rotation shaft 24b. Therefore, the mounting table 14 rotates around the axis X according to the rotation of the rotating shaft 24b. Note that an elastic sealing member such as an O-ring for sealing the processing chamber C may be provided between the lower member 12 a of the processing container 12 and the drive mechanism 24.

  The plasma processing apparatus 10 includes a heater 26 for heating the substrate W placed on the placement region 14a below the placement table 14 in the processing chamber C. Specifically, the substrate W placed on the mounting table 14 is heated by heating the mounting table 14. The substrate W is loaded into the processing chamber C by a transfer device such as a robot arm (not shown) via a gate valve G provided in the processing container 12 and placed on the placement region 14a. The substrate W is unloaded from the processing chamber C via the gate valve G by the transfer device.

  For example, as shown in FIG. 2, the processing chamber C forms a first region R1 and a second region R2 arranged on a circumference around the axis X. The substrate W placed on the placement region 14a sequentially passes through the first region R1 and the second region R2 as the placement table 14 rotates.

  In the plasma processing apparatus 10, for example, as illustrated in FIG. 4, the first gas supply unit 16 is disposed above the first region R <b> 1 so as to face the upper surface of the mounting table 14. The first gas supply unit 16 includes an injection unit 16a. That is, the area | region which faces the injection part 16a among the area | regions contained in the process chamber C is 1st area | region R1.

  The injection unit 16a includes a plurality of injection ports 16h. The first gas supply unit 16 supplies the precursor gas to the first region R1 through the plurality of injection ports 16h. By supplying the precursor gas to the first region R1, atoms or molecules of the precursor gas are chemically adsorbed on the surface of the substrate W that passes through the first region R1. The precursor gas is, for example, DCS (dichlorosilane), monochlorosilane, trichlorosilane, or the like.

  An exhaust port 18 a of the exhaust unit 18 is provided above the first region R <b> 1 so as to face the upper surface of the mounting table 14. The exhaust port 18a is provided around the injection unit 16a. The exhaust unit 18 exhausts the gas in the processing chamber C through the exhaust port 18a by the operation of the exhaust device 34 such as a vacuum pump.

  Above the first region R1, an injection port 20a of the second gas supply unit 20 is provided so as to face the upper surface of the mounting table. The injection port 20a is provided around the exhaust port 18a. The second gas supply unit 20 supplies the purge gas to the first region R1 through the injection port 20a. The purge gas supplied by the second gas supply unit 20 is an inert gas such as Ar (argon). By ejecting the purge gas onto the surface of the substrate W, the atoms or molecules (residual gas components) of the precursor gas excessively chemisorbed on the substrate W are removed from the substrate W. As a result, an atomic layer or a molecular layer in which atoms or molecules of the precursor gas are chemisorbed is formed on the surface of the substrate W.

  The plasma processing apparatus 10 ejects purge gas from the ejection port 20a and exhausts the purge gas along the surface of the mounting table 14 from the exhaust port 18a. Thereby, the plasma processing apparatus 10 suppresses the precursor gas supplied to the first region R1 from leaking out of the first region R1. Further, since the plasma processing apparatus 10 injects purge gas from the injection port 20a and exhausts the purge gas along the surface of the mounting table 14 from the exhaust port 18a, the reaction gas supplied to the second region R2 or a radical of the reaction gas And the like are prevented from entering the first region R1. That is, the plasma processing apparatus 10 separates the first region R1 and the second region R2 by jetting purge gas from the second gas supply unit 20 and exhausting from the exhaust unit 18.

  The plasma processing apparatus 10 includes a unit U including an injection unit 16a, an exhaust port 18a, and an injection port 20a. That is, the injection part 16a, the exhaust port 18a, and the injection port 20a are formed as parts constituting the unit U. For example, as shown in FIG. 4, the unit U has a structure in which a first member M1, a second member M2, a third member M3, and a fourth member M4 are sequentially stacked. The unit U is attached to the processing container 12 so as to contact the lower surface of the upper member 12b of the processing container 12.

  In the unit U, for example, as shown in FIG. 4, a gas supply path 16p that penetrates the second member M2 to the fourth member M4 is formed. An upper end of the gas supply path 16p is connected to a gas supply path 12p provided in the upper member 12b of the processing container 12. A gas supply source 16g of precursor gas is connected to the gas supply path 12p via a valve 16v and a flow rate controller 16c such as a mass flow controller. The lower end of the gas supply path 16p is connected to a space 16d formed between the first member M1 and the second member M2. The injection port 16h of the injection part 16a provided in the first member M1 is connected to the space 16d.

  In the unit U, a gas supply path 20r penetrating the fourth member M4 is formed. The upper end of the gas supply path 20r is connected to the gas supply path 12r provided in the upper member 12b of the processing container 12. A gas supply source 20g of purge gas is connected to the gas supply path 12r via a valve 20v and a flow rate controller 20c such as a mass flow controller.

  In the unit U, the lower end of the gas supply path 20r is connected to a space 20d provided between the lower surface of the fourth member M4 and the upper surface of the third member M3. Moreover, the 4th member M4 forms the recessed part which accommodates the 1st member M1-the 3rd member M3. A gap 20p is provided between the inner surface of the fourth member M4 that forms the recess and the outer surface of the third member M3. The gap 20p is connected to the space 20d. The lower end of the gap 20p functions as the injection port 20a.

  In the unit U, an exhaust path 18q that penetrates the third member M3 and the fourth member M4 is formed. The upper end of the exhaust path 18q is connected to the exhaust path 12q provided in the upper member 12b of the processing container 12. The exhaust path 12q is connected to an exhaust device 34 such as a vacuum pump. The lower end of the exhaust path 18q is connected to a space 18d provided between the lower surface of the third member M3 and the upper surface of the second member M2.

  The third member M3 includes a recess that accommodates the first member M1 and the second member M2. A gap 18g is provided between the inner surface of the third member M3 constituting the recess provided in the third member M3 and the outer surfaces of the first member M1 and the second member M2. The space 18d is connected to the gap 18g. The lower end of the gap 18g functions as the exhaust port 18a. The plasma processing apparatus 10 ejects the purge gas from the injection port 20a and exhausts the purge gas along the surface of the mounting table 14 from the exhaust port 18a, so that the precursor gas supplied to the first region R1 is in the first region. Suppresses leakage out of R1.

  For example, as shown in FIG. 5, the plasma processing apparatus 10 includes a plasma generation unit 22 provided in the opening AP of the upper member 12 b provided above the second region R <b> 2 so as to face the upper surface of the mounting table 14. Is provided. The plasma generation unit 22 includes an antenna 22a and a coaxial waveguide 22b that supplies a microwave to the antenna 22a. In the present embodiment, for example, three openings AP are formed in the upper member 12b, and the plasma processing apparatus 10 includes, for example, three plasma generation units 22.

  The plasma generation unit 22 supplies a reactive gas and a microwave to the second region R2, and generates a reactive gas plasma in the second region R2. When a nitrogen-containing gas is used as the reaction gas, the plasma generating unit 22 nitrides the atomic layer or the molecular layer that is chemically adsorbed on the substrate W. As the reaction gas, for example, a nitrogen-containing gas such as N2 (nitrogen) or NH3 (ammonia) can be used.

  For example, as shown in FIG. 5, the plasma generation unit 22 arranges the antenna 22a in an airtight manner so as to close the opening AP. The antenna 22 a includes a top plate 40, a slot plate 42, and a slow wave plate 44.

  6 and 7 are diagrams illustrating an example of the top board 40. FIG. 6 shows an example of the shape of the top board 40 when the top board 40 is viewed from above along the axis X, and FIG. 7 shows the top board when the top board 40 is viewed from below along the axis X. An example of 40 shapes is shown. The top plate 40 is formed of a dielectric, and has, for example, a flat plate portion 40a and ribs 40b that protrude upward from the flat plate portion 40a along the periphery of the flat plate portion 40a, as shown in FIGS. In the present embodiment, the rib 40b is formed on the flat plate portion 40a over the entire circumference of the peripheral edge of the flat plate portion 40a.

  In the present embodiment, for example, as shown in FIGS. 6 and 7, the top plate 40 has a substantially regular triangular shape with rounded corners when viewed from the direction of the axis X, for example. In the present embodiment, the top plate 40 is made of alumina, for example. The top plate 40 may be formed of quartz, aluminum nitride, silicon nitride, yttrium oxide, or the like in addition to alumina. The top plate 40 is supported by the upper member 12b so that the lower surface of the flat plate portion 40a is exposed to the second region R2 from the opening AP formed in the upper member 12b of the processing container 12.

  In the top plate 40 of the present embodiment, at least the region of the lower surface of the flat plate portion 40a facing the region through which the substrate W placed on the placement region 14a passes is formed in a planar shape. And the area | region of the lower surface of the flat plate part 40a formed in planar shape is coated by Al2O3, Y2O3, YF2, etc., for example. These coatings can be performed by thermal spraying or aerosol deposition. Thereby, the contamination which generate | occur | produces when the material of the top plate 40 adheres to the surface of the board | substrate W in the process of the board | substrate W can be prevented. In the present embodiment, since the lower surface of the flat plate portion 40a is formed in a flat shape, the adhesion of the film coated on the lower surface of the flat plate portion 40a can be improved.

  On the top plate 40, a slot plate 42 is provided. The slot plate 42 is disposed in a region surrounded by the ribs 40 b of the top plate 40. FIG. 8 is a view showing an example of the slot plate 42. The slot plate 42 is formed in a plate shape from metal. For example, as shown in FIG. 8, the shape of the slot plate 42 when viewed from the direction of the axis X is, for example, a substantially regular triangle shape with rounded corners. The slot plate 42 is formed with a plurality of slot pairs 42c as shown in FIG. 8, for example. Each slot pair 42c includes two slot holes 42a and 42b which are long holes extending in a direction intersecting or orthogonal to each other. A plurality of these slot pairs 42 c are formed in the circumferential direction in concentric circles having different radii in the plane of the slot plate 42. The slot plate 42 is provided with an opening 42d for arranging the coaxial waveguide 22b. The slot plate 42 is an example of a conductor plate.

  A slow wave plate 44 is provided on the slot plate 42. The slow wave plate 44 is disposed in a region surrounded by the slow wave plate 44 b of the top plate 40. FIG. 9 is a diagram illustrating an example of the slow wave plate 44. The slow wave plate 44 is formed of a dielectric material such as alumina. For example, as illustrated in FIG. 9, the slow wave plate 44 has a substantially regular triangular shape with rounded corners when viewed from the direction of the axis X. The slow wave plate 44 is provided with a substantially cylindrical opening for disposing the outer conductor 62b of the coaxial waveguide 22b. A ring-shaped protrusion 44 a that protrudes in the thickness direction of the slow wave plate 44 is provided at the inner diameter side end of the slow wave plate 44 that forms the periphery of the opening. The slow wave plate 44 is mounted on the slot plate 42 so that the protruding portion 44a protrudes upward.

  A cooling plate 46 is provided on the upper surface of the slow wave plate 44. The cooling plate 46 cools the antenna 22a through the slow wave plate 44 by the refrigerant flowing through the flow path formed therein. The surface of the cooling plate 46 is made of metal. The cooling plate 46 is pressed against the upper surface of the slow wave plate 44 by a spring such as a spiral spring gasket (not shown), and the lower surface of the cooling plate 46 is in close contact with the upper surface of the slow wave plate 44. Thereby, the antenna 22a can efficiently radiate heat through the cooling plate 46.

  The coaxial waveguide 22b includes a hollow substantially cylindrical inner conductor 62a and outer conductor 62b. The inner conductor 62a passes through the opening of the slow wave plate 44 and the opening of the slot plate 42 from above the antenna 22a. The outer conductor 62b is provided so as to surround the inner conductor 62a with a gap between the outer peripheral surface of the inner conductor 62a and the inner peripheral surface of the outer conductor 62b. The lower end of the outer conductor 62 b is connected to the opening of the cooling plate 46. Between the inner conductor 62a and the outer conductor 62b, a plurality of stubs 80 are inserted obliquely downward from the outer conductor 62b toward the inner conductor 62a. By controlling the insertion amount of each stub 80, the distribution of microwaves radiated from the lower surface of the top plate 40 to the second region R2 can be controlled.

  The plasma processing apparatus 10 includes a waveguide 60 and a high frequency generator 68. The high frequency generator 68 generates a high frequency included in a band of 1 MHz to 3 THz, for example. In the present embodiment, the high frequency generator 68 generates a microwave (for example, a microwave of 2.45 GHz) included in a band of 300 MHz to 3 THz. For example, a microwave of about 2.45 GHz generated by the high-frequency generator 68 propagates to the coaxial waveguide 22b via the waveguide 60, and propagates through the gap between the inner conductor 62a and the outer conductor 62b. The microwave propagated in the slow wave plate 44 propagates from the slot hole of the slot plate 42 to the top plate 40 and is radiated from the top plate 40 to the second region R2.

  The reaction gas is supplied from the reaction gas supply unit 22c to the second region R2. For example, a plurality of reaction gas supply units 22 c are provided inside the upper member 12 b of the processing container 12 so as to extend around the opening AP, and the reaction gas supply unit 22 c injects the reaction gas toward the lower side of the top plate 40. A reaction gas supply source 50g is connected to the reaction gas supply unit 22c via a valve 50v and a flow rate controller 50c such as a mass flow controller.

  The plasma generation unit 22 supplies the reaction gas to the second region R2 by the reaction gas supply unit 22c, and radiates the microwave to the second region R2 by the antenna 22a. Thereby, a reactive gas plasma is generated in the second region R2.

  As shown in FIG. 3, the plasma processing apparatus 10 includes a control unit 70 for controlling each component of the plasma processing apparatus 10. The control unit 70 may be a computer including a control device such as a CPU (Central Processing Unit), a storage device such as a memory, an input / output device, and the like. The control unit 70 controls each component of the plasma processing apparatus 10 based on the operation of the CPU according to the control program stored in the memory.

  For example, the control unit 70 outputs a control signal for controlling the rotation speed of the mounting table 14 to the driving device 24a. Further, the control unit 70 outputs a control signal for controlling the temperature of the substrate W to a power source connected to the heater 26. Further, the control unit 70 outputs a control signal for controlling the flow rate of the precursor gas to the valve 16v and the flow rate controller 16c. Further, the control unit 70 outputs a control signal for controlling the exhaust amount to the exhaust device 34.

  Further, the control unit 70 outputs a control signal for controlling the flow rate of the purge gas to the valve 20v and the flow rate controller 20c. Further, the control unit 70 outputs a control signal for controlling the power of the microwave to the high frequency generator 68. Further, the control unit 70 outputs a control signal for controlling the flow rate of the reaction gas to the valve 50v and the flow rate controller 50c. Further, the control unit 70 transmits a control signal for controlling the exhaust amount from the exhaust port 22h to the exhaust device 52.

[Shape of top plate 40]
In the plasma processing of the substrate W using the plasma processing apparatus 10, the inside of the processing container 12 is set to a pressure lower than the atmospheric pressure. Therefore, a pressure corresponding to a differential pressure between the atmospheric pressure and the pressure in the processing container 12 is applied to the top plate 40. Therefore, the top plate 40 may be provided with ribs in order to ensure strength against pressure. In the plasma treatment using microwaves, when the distance between the antenna 22a and the substrate W is shortened, the amount of radicals supplied to the substrate W is increased, and the quality of the film formed on the substrate W is improved. However, if a rib is provided on the surface of the top plate 40 on the mounting table 14 side in order to ensure the mechanical strength of the top plate 40, it is difficult to bring the antenna 22a closer to the substrate W by the height of the rib. Become. Therefore, it becomes difficult to improve the quality of the film formed on the substrate W.

  Then, the inventors examined using the top plate 40 in which the rib is not provided in the surface at the mounting base 14 side. When the first principal stress of the top plate in the case where the plasma treatment was performed using a plate-like top plate without ribs was obtained, a simulation result as shown in FIG. 10 was obtained. FIG. 10 is a diagram illustrating an example of a simulation result of the first principal stress of the top plate on which no rib is provided. In the simulation result shown in FIG. 10, the simulation of the first principal stress of the top plate when the power of the microwave supplied from the antenna 22a is changed for the top plate of three thicknesses L1 of 11 mm, 13 mm, and 16 mm. Results are shown. In the simulation results shown in FIG. 10, alumina is used as the top plate material.

  As is apparent from the results of FIG. 10, the first principal stress of the top plate increases as the microwave power increases in any top plate of thickness L1. And in the top plate whose thickness L1 is 11 mm or 13 mm, the 1st main stress at the time of supplying a microwave of 5 kW exceeds 75 MPa. In the top plate having a thickness L1 of 16 mm, the first principal stress when a microwave of 5 kW is supplied is a value in the vicinity of 75 MPa.

  Here, in the present embodiment, the upper limit value of the first principal stress when a microwave of 5 kW is supplied is determined to be 75 MPa from the past use record of the top board. Referring to the simulation result of FIG. 10, it can be seen that the first principal stress when a microwave of 5 kW is supplied exceeds the upper limit value on a top plate having a thickness L1 of 11 mm or 13 mm. Moreover, in the top plate with a thickness L1 of 16 mm, the first principal stress when a microwave of 5 kW is supplied is a value near 75 MPa, and it can be seen that there is no margin with respect to the upper limit value. Therefore, it was found that the strength could not be secured when a plate-like top plate without ribs was used.

  Next, the simulation result of the top plate provided with ribs will be described. If ribs are provided on the surface of the top plate on the mounting table 14 side, it is difficult to bring the antenna 22a closer to the substrate W by the height of the ribs. Therefore, in this embodiment, for example, as described with reference to FIGS. 6 and 7, the top plate 40 provided with ribs on the entire periphery of the surface opposite to the surface on the mounting table 14 side is used.

  Here, parameters used in the simulation will be described. FIG. 11 is a diagram illustrating the height and width of the rib. As shown in FIG. 11, in the top plate 40, the thickness of the flat plate portion 40a is defined as L1, the height of the rib 40b from the flat plate portion 40a is defined as L2, and the width of the rib 40b is defined as L3.

  The flat plate portion 40 a of the top plate 40 is disposed below the slot plate 42. The microwaves radiated from the respective slot holes 42a and 42b provided in the slot plate 42 propagate through the top plate 40 and are radiated from the top plate 40 to the second region R2. Here, in order to increase the mechanical strength, it is conceivable to increase the thickness L1 of the top board 40. However, when the thickness L1 of the top plate 40 is increased, the microwaves radiated from the slot holes 42a and 42b are likely to spread in the in-plane direction of the top plate 40, and the microwaves are fixed on the top plate 40. Standing waves are likely to occur. When a microwave standing wave is generated, the microwave may be strengthened at a position different from that immediately below the slot holes 42 a and 42 b in the plane of the top plate 40. Therefore, the microwave has a distribution different from the arrangement of the slot holes 42a and 42b, and the controllability of the microwave distribution is lowered. As a result, poor ignition of plasma and uneven plasma distribution occur. Therefore, it is not preferable that the flat plate portion 40a is too thick.

  In the present embodiment, from the viewpoint of mechanical strength and controllability of the microwave distribution, the thickness L1 of the flat plate portion 40a is, for example, λ / 8 when the wavelength of the microwave in the top plate 40 is λ. The thickness is preferably in the range of -3λ / 8. When the material of the top plate 40 is alumina, the thickness L1 of the flat plate portion 40a is preferably in the range of about 5 mm to 15 mm, for example, with respect to the microwave of 2.45 GHz. From the viewpoint of controllability of the microwave distribution, the thickness L1 of the flat plate portion 40a is more preferably λ / 4. When the material of the top plate 40 is alumina, the wavelength of the 2.45 GHz microwave in the top plate 40 is about 40 mm. Therefore, from the viewpoint of controllability of the microwave distribution, the thickness L1 of the flat plate portion 40a. Is preferably about 10 mm. However, considering the mechanical strength, it is considered that the margin of strength is small at a thickness of about 10 mm. Therefore, in the following, the simulation was performed with the thickness L1 of the flat plate portion 40a being 13 mm.

  FIG. 12 is a diagram illustrating an example of a simulation result of the top plate 40 provided with ribs. In the simulation result shown in FIG. 12, alumina is used as the material of the top plate 40.

  As is apparent from the simulation results of FIG. 12, the increase in the first principal stress is suppressed with respect to the increase in the intensity of the microwave as the height L2 of the rib 40b is increased. However, when the height L2 of the rib 40b becomes too high, the stress concentrated on the connection portion between the rib 40b and the flat plate portion 40a tends to increase. Therefore, the height L2 of the rib 40b is preferably within a predetermined range, for example, preferably within a range of 2 to 4 times the thickness L1 of the flat plate portion 40a. In the present embodiment, the height L2 of the rib 40b is preferably in the range of 20 mm to 40 mm, for example.

  As is clear from the simulation results of FIG. 12, the increase in the first principal stress is suppressed as the microwave L increases as the width L3 of the rib 40b increases. However, if the width L3 of the rib 40b is too large, the area of the flat plate portion 40a for arranging the slot plate 42 and the slow wave plate 44 becomes narrow. Therefore, the width L3 of the rib 40b is preferably within a predetermined range, for example, preferably within a range of 1 to 1.5 times the thickness L1 of the flat plate portion 40a. In the present embodiment, the width L3 of the rib 40b is preferably within a range of 10 mm to 15 mm, for example.

  As is apparent from FIG. 12, in the simulation, the thickness L1 of the flat plate portion 40a is set to 13 mm, the height L2 of the rib 40b is set to 27.5 mm, and the width L3 of the rib 40b is set to 12.5 mm. It was confirmed that the generated first principal stress can be suppressed to 62.9 MPa.

  As described above, in this embodiment, for example, as shown in FIGS. 5 to 7, by using the top plate 40 provided with the rib on the surface opposite to the surface on the mounting table 14 side, the mounting table 14 side is used. Even when the rib is not provided on the surface, the first principal stress generated in the top plate 40 can be suppressed to a predetermined value or less. Thereby, the distance between the antenna 22a and the board | substrate W can be shortened.

  For example, in the conventional plasma processing apparatus 10 using the top plate 40 with the ribs formed on the lower surface, the distance from the lower surface of the top plate 40 other than the ribs to the substrate W was 67 mm. On the other hand, in the plasma processing apparatus 10 of this embodiment, the distance from the lower surface of the top plate 40 to the substrate W could be shortened to 45.7 mm. That is, in the plasma processing apparatus 10 of the present embodiment, the distance from the top plate 40 to the substrate W can be shortened by 21.3 mm compared to the conventional plasma processing apparatus 10.

  Thus, by shortening the distance between the antenna 22a and the substrate W, radicals generated in the vicinity of the antenna 22a can reach the substrate W more easily. Therefore, the amount of radicals supplied to the substrate W can be increased, and the film quality of the substrate W can be improved even at a lower processing temperature.

  It should be noted that if the distance between the top plate 40 and the substrate W is too short, charge-up damage occurs on the substrate W. In the experiment, charge-up damage occurred on the substrate W when the distance between the lower surface of the top plate 40 and the substrate W was less than 30 mm. For this reason, it is not preferable to make the distance between the antenna 22a and the substrate W too short. Therefore, in the present embodiment, the distance between the antenna 22a and the substrate W is preferably within a predetermined range, for example, preferably within a range of 3 to 4 times the thickness L1 of the flat plate portion 40a. In the present embodiment, the distance between the antenna 22a and the substrate W is preferably in the range of 30 mm to 40 mm, for example.

  The embodiment has been described above. According to the plasma processing apparatus 10 of the present embodiment, the film quality of the substrate W can be improved. In particular, according to the plasma processing apparatus 10 of the present embodiment, the bottom surface of the top plate 40 can be flattened while the thickness L1 of the top plate 40 on the bottom surface of the antenna 22a is maintained at a thickness of 3λ / 8 or less. The improvement in the controllability of the microwave distribution in the plasma generation region and the increase in the amount of radicals supplied to the substrate W can both be achieved.

  Note that the disclosed technique is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist.

  For example, in the above-described embodiment, the antenna 22a is a substantially equilateral triangular antenna 22a when viewed from the direction along the axis X, but the disclosed technique is not limited thereto. As another form, the shape of the antenna 22a when viewed from the direction along the axis X may be a shape other than a substantially equilateral triangle, for example, a substantially circular shape or a polygonal shape.

  In the above-described embodiment, a semi-batch type substrate processing apparatus has been described as an example of the plasma processing apparatus 10. However, the disclosed technology is not limited to this. For example, the top plate 40 may be used for the single-wafer plasma processing apparatus 10.

  Moreover, the top plate 40 in the above-described embodiment is provided with ribs 40b over the entire periphery of the periphery of the flat plate portion 40a. However, the disclosed technology is not limited to this. For example, the rib 40b may not be provided in a part of the periphery of the flat plate portion 40a. In addition, when the shape of the top plate 40 when viewed from the direction along the axis X is a substantially equilateral triangle shape, the stress tends to concentrate on the corner portion. Therefore, even when the rib 40b is not provided on the entire circumference of the peripheral edge of the flat plate portion 40a, it is preferable that the rib 40b is provided at the corner portion. Moreover, the rib 40b may be provided in parts other than the periphery of the flat plate part 40a.

  Moreover, the rib 40b should just be provided in the upper surface (surface on the opposite side to the surface facing the mounting base 14) of the flat plate part 40a, and does not necessarily need to be provided in the periphery of the upper surface of the flat plate part 40a. Good. However, in this case, the rib 40b is preferably provided in a region other than the region where the slot plate 42 is disposed on the upper surface of the flat plate portion 40a.

  In the above-described embodiment, the rib 40b of the top plate 40 protrudes from the flat plate portion 40a to the side opposite to the surface facing the mounting table 14 along the peripheral edge of the flat plate portion 40a. Not limited to. For example, as shown in FIG. 13, the rib 40b protrudes from the flat plate portion 40a to the opposite side of the surface facing the mounting table 14 along the peripheral edge of the flat plate portion 40a, and is further in a direction substantially parallel to the surface of the flat plate portion 40a. The shape which protrudes outside along may be sufficient. As a result, the entire antenna 22a can be brought closer to the substrate W while maintaining the mechanical strength of the top board 40.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above-described embodiment. In addition, it is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

W substrate 10 plasma processing apparatus 12 processing container 14 mounting table 16 first gas supply unit 18 exhaust unit 20 second gas supply unit 22 plasma generation unit 22a antenna 22b coaxial waveguide 22c reactive gas supply unit 24 drive mechanism 26 heater 34 Exhaust device 40 Top plate 40a Flat plate portion 40b Rib 42 Slot plate 44 Slow wave plate

Claims (11)

In a plasma processing apparatus for processing a substrate to be processed in a processing container using microwave plasma,
A mounting table provided in the processing container, on which the substrate to be processed is mounted;
Provided above the mounting table so as to face the mounting table, having a dielectric plate, and supplying microwaves into the processing container through the dielectric plate. An antenna for generating a plasma of the treated gas,
The dielectric plate is
A flat plate portion provided on the lower surface of the antenna and having at least a surface facing the mounting table formed in a planar shape;
It possesses a rib formed on the surface opposite to the mounting table facing the side surface in said plate,
Height from the flat portion of the rib, the plasma processing apparatus according to claim range der Rukoto from twice 4 times the thickness of said plate. The antenna is
The flat plate portion is provided so as to be in contact with the surface opposite to the surface facing the mounting table, and has a conductor plate that propagates the microwave,
The rib is
2. The plasma processing apparatus according to claim 1, wherein the flat plate portion is formed in a region where the conductive plate is not provided in a surface opposite to the surface facing the mounting table. The rib is
The said flat plate part is formed along the peripheral edge of the surface on the opposite side to the surface opposite to the mounting table in the said flat plate part so that it may protrude upwards from the said flat plate part. Plasma processing equipment. The said rib is provided in the said flat plate part over the perimeter of the surface on the opposite side to the surface on the opposite side to the said mounting base in the said flat plate part, The plasma processing apparatus of Claim 3 characterized by the above-mentioned. .   5. The thickness of the flat plate portion is in the range of λ / 8 to 3λ / 8, where λ is the wavelength of the microwave in the dielectric plate. 6. The plasma processing apparatus according to item. The thickness of the ribs, the plasma processing apparatus according to any one of claims 1 to 5, characterized in that in the range of 1.5 times the 1 times the thickness of said plate. The plasma processing apparatus according to any one of claims 1 to 6 , wherein the flat plate portion is provided with a predetermined coating on a planar surface on the side facing the mounting table. The distance between the substrate to be processed placed on the lower surface and the mounting table of said plate, from the claims 1 to 7, characterized in that from 3 times the thickness of said plate is in the range 4 times The plasma processing apparatus according to any one of claims. It said dielectric plate, alumina, quartz, aluminum nitride, plasma processing apparatus according to any one of claims 1 to 8, characterized in that it is formed of silicon nitride or oxide of yttrium. The mounting table is provided rotatably about the axis so that the substrate to be processed moves around the axis.
The processing container is divided into a plurality of regions in a circumferential direction in which the substrate to be processed moves with respect to the axis by rotation of the mounting table.
The antenna generates plasma of a processing gas supplied into the processing container by radiating a microwave into the processing container in one of the plurality of regions. Item 10. The plasma processing apparatus according to any one of Items 1 to 9 . The antenna, the cross-sectional shape when viewed from the direction along the axis, the plasma processing apparatus according to claim 1 0, characterized in that a substantially equilateral triangle shape.

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