JP2007335346A - Microwave introduction device, and plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave introduction device with generation of gaps at a power-feeding part restrained, by improving dimensional accuracy at processing through simplification of shapes of the power-feeding part of a slow-wave member. <P>SOLUTION: In the microwave introduction device provided with a microwave generator 114, a flat-face antenna member 94 with a slot 96 for microwave radiation formed, a waveguide 108 for propagating microwaves generated by the microwave generator to the flat-face antenna member, and a flat-plate slow-wave member 98 provided overlapped with the flat-face antenna member and with a convex power-feeding part 100 formed at a center part for feeding power from the waveguide 108 and shortening wavelengths of the microwaves propagated, the waveguide consists of a center conductor 108A and an outside conductor 108B, of which, the former is connected to a center part of the flat-face antenna member through a through-hole formed at the power-feeding part, and side walls of the convex power-feeding part are formed substantially erected in a perpendicular direction against the flat-face direction of the slow-wave member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microwave introduction apparatus and a plasma processing apparatus used when processing is performed by applying plasma generated by microwaves to a semiconductor wafer or the like.

In recent years, with the increase in the density and miniaturization of semiconductor products, plasma processing apparatuses are often used for various processes such as film formation, etching, and ashing in the manufacturing process of semiconductor products, and in particular, 0.1 mTorr. (13.3 mPa) to several Torr (several hundreds Pa) A microwave plasma apparatus that generates high-density plasma using microwaves because it can stably generate plasma even in a high vacuum state where the pressure is relatively low. Tend to be used.
Such a plasma processing apparatus is disclosed in Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, and the like. Here, a general plasma processing apparatus using a microwave will be schematically described with reference to FIGS. 6 is a schematic configuration diagram showing a conventional general plasma processing apparatus, FIG. 7 is an enlarged view showing a central portion of a planar antenna member and a slow wave member, and FIG. 8 is a perspective view showing a central portion of the slow wave member. .

  In FIG. 6, the plasma processing apparatus 2 includes a mounting table 6 on which a semiconductor wafer W is mounted in a processing container 4 that can be evacuated, and microwaves are applied to a ceiling portion that faces the mounting table 6. A top plate 8 made of transparent disc-shaped alumina, aluminum nitride, quartz or the like is provided in an airtight manner. The side wall of the processing vessel 4 is provided with, for example, a gas nozzle 10 as a gas introduction means for introducing a predetermined gas into the vessel, and an opening 12 for loading / unloading the wafer W is provided. The part 12 is provided with a gate valve G that opens and closes the airtightly. Further, an exhaust port 14 is provided at the bottom of the processing container 4, and a vacuum exhaust system (not shown) is connected to the exhaust port 14 so that the processing container 4 can be evacuated as described above. Yes.

  A microwave introducing device 16 for introducing a microwave for plasma formation into the processing container 4 is provided above the top plate 8. Specifically, the microwave introducing device 16 includes a disk-shaped planar antenna member 18 made of, for example, a copper plate having a thickness of about several millimeters provided on the top surface of the top plate 8, and a radius of the planar antenna member 18. And a slow wave member 20 made of, for example, a dielectric for shortening the wavelength of the microwave in the direction. The planar antenna member 18 is formed with a number of microwave radiating slots 22 made of, for example, long groove-like through holes. The slots 22 are generally arranged concentrically or spirally. As shown in FIGS. 7 and 8, the frustoconical power feeding portion 26 is formed so that the central portion of the upper surface of the slow wave member 20 protrudes upward in a convex shape so that the inclined surface becomes a conical tapered surface. And a through hole 28 is formed in the power feeding portion 26.

  The central conductor 24A of the coaxial waveguide 24 is connected to the planar antenna member 18 through the through-hole 28, and the outer conductor 24B of the coaxial waveguide 24 is guided to cover the entire slow wave member 20. The central part of the box 30 is connected. Then, for example, a 2.45 GHz microwave generated from the microwave generator 32 is converted into a predetermined vibration mode by the mode converter 34 and then guided to the planar antenna member 18 and the slow wave member 20. Then, while propagating the microwaves radially in the radial direction of the antenna member 18, the microwaves are radiated from the slots 22 provided in the planar antenna member 18 and are transmitted through the top plate 8. A microwave is introduced into the semiconductor wafer W, and plasma is generated in the processing space S in the processing container 4 by the microwave to perform a predetermined plasma processing such as etching or film formation on the semiconductor wafer W. A cooler 36 for cooling the slow wave member 20 heated by the dielectric loss of the microwave is provided on the upper surface of the waveguide box 30.

Japanese Patent Laid-Open No. 3-191073 JP-A-5-343334 Japanese Patent Laid-Open No. 9-181052 JP 2003-332326 A

  By the way, in this kind of microwave introducing device 16, in order to increase the propagation efficiency of the microwave as much as possible, it is required to suppress the reflected wave as much as possible as is well known. Therefore, even when microwaves propagate from the lower end portion of the coaxial waveguide 24 to the planar antenna member 18 and the slow wave member 20 via the power feeding portion 26, this portion is used to suppress reflection of the microwaves. It is preferable to change the characteristic impedance as smoothly as possible. Therefore, as described above, the convex feeding portion 26 at the center of the slow wave member 20 is set to have a frustoconical shape whose side surface 26A is a tapered surface so that the characteristic impedance is reduced as smoothly as possible. ing. As a result, the characteristic impedance of the coaxial waveguide 24 is 50Ω, for example, 15.9Ω at the boundary portion between the feeding portion 26 and the coaxial waveguide 24, and, for example, 7.4Ω and 1.5Ω as it goes to the peripheral portion. As shown in FIG.

  However, the dielectric quartz or ceramic, such as aluminum nitride or alumina, which is the material of the slow wave member 20, is very hard and brittle, and it is very difficult to increase the processing accuracy. For example, the thickness of the slow wave member 20 and the height H0 of the power feeding portion 26 are both about 3 to 10 mm, but it is quite difficult to increase the processing accuracy of the taper machining of hard material. The processing accuracy at the time of polishing in the taper processing is at most about ± 0.5 mm, and a relatively large variation occurs in processing dimensions. For this reason, as shown in FIG. 7, it is inevitable that a gap 38 having a dimension or more between the tapered side surface 26 </ b> A of the power feeding portion 26 and the inner surface of the waveguide box 30 is generated.

Therefore, there is a problem that the electric field of the microwave is concentrated in the gap 38 and abnormal discharge occurs, or the symmetry of the electric field distribution in the planar antenna member 18 is broken due to the gap 38. there were.
In addition, since the gap 38 is irregularly generated, it becomes difficult to set the characteristic impedance as designed, and the microwave reflectance in this portion is increased.

Still further, due to the gap 38, the power feeding portion 26 of the slow wave member 20 is separated from the inner wall surface of the wave guide box 30 provided with the cooler 36, and the thermal conductivity therebetween becomes poor, As a result, there is a problem that the cooling efficiency in the vicinity of the power feeding unit 26 is lowered.
The present invention has been devised to pay attention to the above problems and to effectively solve them. The object of the present invention is to improve the dimensional accuracy during processing by simplifying the shape of the power feeding part of the slow wave member, thereby suppressing the occurrence of gaps in the power feeding part that caused various problems. An object of the present invention is to provide a microwave introduction apparatus and a plasma processing apparatus that can be used.

  According to a first aspect of the present invention, a microwave generator for generating a microwave, a planar antenna member in which a slot for microwave radiation is formed, and a microwave generated by the microwave generator are supplied to the planar antenna member. A waveguide to be propagated and a convex feed portion that feeds power from the waveguide is formed at the center and overlapped with the planar antenna member to shorten the wavelength of the propagating microwave In the microwave introducing device, the waveguide includes a coaxial waveguide including a center conductor and an outer conductor, and the center conductor is formed in the feeding portion. It is connected to the central portion of the planar antenna member through a through hole, and the side wall of the convex feeding portion is formed to stand in a direction substantially perpendicular to the planar direction of the slow wave member. thing A microwave introduction device according to claim.

In this way, the side wall of the convex feeding portion that feeds power from the waveguide is formed so as to be perpendicular to the plane direction of the slow wave member so as to be perpendicular to the plane direction. Processing such as polishing can be easily performed, and dimensional accuracy during processing can be improved.
Accordingly, since it is possible to suppress the occurrence of a gap between the feeding portion and the inner diameter of the waveguide box or waveguide covering the feeding portion, not only abnormal discharge can be prevented from occurring in this portion, but also the planar antenna member It is possible to prevent the symmetry of the electric field distribution at.
Moreover, since generation | occurrence | production of a clearance gap can be suppressed as mentioned above, it can set to the characteristic impedance as designed, and the reflectance of a microwave can be suppressed.

In this case, for example, as described in claim 2, the slow wave member is made of a dielectric.
For example, as described in claim 3, the height of the convex feeding portion from the upper surface of the slow wave member is set in a range of 6.5 to 13.0 mm.
For example, as described in claim 4, the slow wave material is made of alumina, and the height of the convex feeding portion is set in a range of 6.5 to 8.5 mm.
For example, as described in claim 5, the slow wave material is made of quartz, and the height of the convex feeding portion is set within a range of 11 to 13 mm.
For example, the slow wave member is covered with a wave guide box made of a conductive material.

For example, as described in claim 7, the wave guide box is provided with a cooling means for cooling the slow wave member.
Thus, when the cooling means is provided, the gap between the inner wall surface of the waveguide provided with the cooling means or the inner wall surface of the waveguide box and the power feeding portion can be suppressed. Thermal conductivity is improved, and the cooling efficiency of the power feeding unit can be improved.
For example, as described in claim 8, the microwave is 2.45 GHz or 8.35 GHz.

The invention according to claim 9 is directed to a processing container in which a ceiling part is opened and an inside thereof is made evacuable, a mounting table provided in the processing container for mounting an object to be processed, A top plate made of a dielectric material that is airtightly attached to the opening and transmits microwaves, a gas introduction unit that introduces a necessary processing gas into the processing container, and the microwave for introducing the microwave into the processing container A plasma processing apparatus comprising: the microwave introduction device according to any one of the above provided on a top plate side.
In this case, for example, as described in claim 10, the top plate and the slow wave member are made of the same material.

According to the microwave introduction apparatus and the plasma processing apparatus according to the present invention, the following excellent operational effects can be exhibited.
Since the side wall of the convex feeding section that feeds power from the waveguide is formed so as to be perpendicular to the plane direction of the slow wave member so as to be perpendicular, processing such as polishing Therefore, the dimensional accuracy during processing can be improved.
Accordingly, since it is possible to suppress the occurrence of a gap between the feeding portion and the inner diameter of the waveguide box or waveguide covering the feeding portion, not only abnormal discharge can be prevented from occurring in this portion, but also the planar antenna member It is possible to prevent the symmetry of the electric field distribution at.
Moreover, since generation | occurrence | production of a clearance gap can be suppressed as mentioned above, it can set to the characteristic impedance as designed, and the reflectance of a microwave can be suppressed.

  In particular, according to the invention according to claim 7, when the cooling means is provided, the gap between the inner wall surface of the waveguide provided with the cooling means or the inner wall surface of the waveguide box and the power feeding portion is suppressed. Therefore, the thermal conductivity of this part is improved, and the cooling efficiency of the power feeding unit can be improved.

EMBODIMENT OF THE INVENTION Below, the form of one Example of the microwave introduction apparatus and plasma processing apparatus concerning this invention is demonstrated with reference to an accompanying drawing.
FIG. 1 is a configuration diagram showing an example of a plasma processing apparatus using a microwave introduction device according to the present invention, and FIG. 2 is an enlarged view showing a central portion of a planar antenna member and a slow wave member in the microwave introduction device of the present invention, FIG. 3 is a perspective view showing a central portion of the slow wave member.

  As shown in the figure, the plasma processing apparatus 42 has a processing container 44 whose side wall and bottom are made of a conductor such as aluminum and formed into a cylindrical shape as a whole, and the inside is sealed, for example, circular. In this processing space S, plasma is formed in the processing space S. The processing container 44 itself is grounded.

In the processing container 44, a mounting table 46 on which, for example, a semiconductor wafer W as a target object is mounted is accommodated on the upper surface. The mounting table 46 is formed in a substantially disc shape made flat, for example, by anodized aluminum or the like, and is erected from the bottom of the container via a column 48 made of aluminum or the like.
A loading / unloading port 50 for loading / unloading a workpiece used for loading / unloading the wafer W to / from the inside of the processing container 44 is provided on the side wall of the processing container 44, and the loading / unloading port 50 is a gate valve that opens and closes in a sealed state. 52 is provided.

  Further, the processing container 44 is provided with a gas introducing means 54 for introducing a necessary processing gas into the processing container 44. Here, the gas introducing means 54 has, for example, a gas nozzle 54A penetrating the side wall of the processing container 44, and a necessary processing gas can be supplied from the gas nozzle 54A as needed while controlling the flow rate. ing. A plurality of gas nozzles 54A may be provided so that different gas types can be introduced, or may be provided on the ceiling of the processing vessel 44 in the form of a shower head.

  Further, an exhaust port 56 is provided at the bottom of the container, and an exhaust path 62 to which a pressure control valve 58 and a vacuum pump 60 are sequentially connected is connected to the exhaust port 56, and processing is performed as necessary. The inside of the container 44 can be evacuated to a predetermined pressure.

  A plurality of, for example, three lifting pins 64 (only two are shown in FIG. 1) for moving the wafer W up and down when the wafer W is loaded and unloaded are provided below the mounting table 46. Is lifted and lowered by a lifting rod 68 provided through the container bottom through an extendable bellows 66. The mounting table 46 is formed with a pin insertion hole 70 through which the elevating pin 64 is inserted. The entire mounting table 46 is made of a heat-resistant material, for example, ceramic such as alumina, and heating means 72 is provided in the ceramic. The heating means 72 is composed of, for example, a thin plate-like resistance heater embedded over substantially the entire area of the mounting table 46, and the heating means 72 is connected to a heater power supply 76 via a wiring 74 that passes through the column 48. ing.

  Further, a thin electrostatic chuck 80 having conductor wires 78 disposed, for example, in a mesh shape is provided on the upper surface side of the mounting table 46, and the electrostatic chuck is described in detail on the mounting table 46. The wafer W placed on the wafer 80 can be attracted by electrostatic attraction force. The conductor wire 78 of the electrostatic chuck 80 is connected to a DC power source 84 via a wiring 82 in order to exert the electrostatic attraction force. The wiring 82 is connected to a bias high-frequency power source 86 for applying a bias high-frequency power of 13.56 MHz to the conductor wire 78 of the electrostatic chuck 80 when necessary. Depending on the processing mode, this bias high-frequency power source 86 is not provided.

The ceiling of the processing container 44 is opened, and is permeable to microwaves made of a dielectric such as quartz or ceramic, such as alumina (Al ₂ O ₃ ) or aluminum nitride (AlN). A top plate 88 is airtightly provided through a seal member 90 such as an O-ring. The thickness of the top plate 88 is set to, for example, about 20 mm in consideration of pressure resistance.

  A microwave introducing device 92 according to the present invention is provided on the upper surface side of the top plate 88. Specifically, the microwave introduction device 92 is provided in contact with the upper surface of the top plate 88 and has a planar antenna member 94 for introducing microwaves into the processing container 44. The planar antenna member 94 is made of a conductive material having a diameter of 400 to 500 mm and a thickness of 1 to several mm, for example, for a wafer having a size of 300 mm, for example, a copper plate or aluminum having a surface plated with silver. The disk is formed with a number of microwave radiating slots 96 formed of, for example, long groove-like through holes. The arrangement form of the slots 96 is not particularly limited. For example, the slots 96 may be arranged concentrically, spirally, or radially, or may be distributed uniformly over the entire antenna member. The planar antenna member 94 has a so-called RLSA (Radial Line Slot Antenna) type antenna structure, whereby high density and low electron energy plasma can be obtained.

  Further, a flat plate-like slow wave member 98 made of, for example, a dielectric such as quartz or ceramic, for example, alumina or aluminum nitride is provided on the planar antenna member 94. The slow wave member 98 has a high dielectric constant characteristic in order to shorten the wavelength of the microwave. The slow wave member 98 is formed in a thin disc shape and is provided over substantially the entire upper surface of the planar antenna member 94, and a feeding portion formed by projecting upward at the center of the upper surface. 100 is formed (see FIG. 3). This power supply unit 100 is set to a predetermined height H1, and its side wall 100A is not formed as a tapered surface as in the conventional power supply unit (see FIG. 8), and as shown in FIG. It is formed in a state where it is erected in a direction substantially perpendicular to 98 plane directions.

That is, the side wall 100A is formed at a right angle to the upper surface of the slow wave member 98, and has a shape that facilitates polishing and the like. The height H1 from the upper surface of the slow wave member 98 of the power feeding unit 100 depends on the material constituting the slow wave member 98, but in order to suppress the reflectance of the microwave, for example, 6.5 to 13. It is good to set within the range of 0 mm.
A through hole 102 is formed in the central portion of the convex power feeding portion 100 so as to penetrate the power feeding portion 100 in the vertical direction, and a lower portion of the through hole 102 is expanded in a divergent shape. The material of the slow wave member 98 is preferably the same material as the top plate 88 in consideration of the wavelength short-circuit effect of microwaves.

  A wave guide box 104 made of a hollow cylindrical container made of a conductor is provided so as to cover the entire upper surface and side surfaces of the slow wave member 98. The planar antenna member 94 is configured as a bottom plate of the waveguide box 104. A cooling jacket 106 is provided on the upper portion of the waveguide box 104 as cooling means for flowing a refrigerant to cool the waveguide box 104.

  Both the waveguide box 104 and the peripheral portion of the planar antenna member 94 are electrically connected to the processing container 44. A coaxial waveguide 108 is connected to the power supply unit 100. Specifically, the coaxial waveguide 108 includes a central conductor 108A and an outer conductor 108B having a circular cross section disposed around the central conductor 108A with a predetermined gap therebetween. The outer conductor 108B having a circular cross section is connected, and the inner center conductor 108A is connected to the center of the planar antenna member 94 through the through hole 102 in the center of the slow wave member 98.

  At this time, the side wall 100A of the convex feeding portion 100 is mounted in a state of being in close contact with the inner wall surface of the outer conductor 108B with high dimensional accuracy. The coaxial waveguide 108 is connected to a microwave generator 114 having a matching (not shown) via a mode converter 110 and a rectangular waveguide 112, for example, a 2.45 GHz microwave generator 114. Microwaves are propagated to the member 94 and the slow wave member 98. This frequency is not limited to 2.45 GHz, and other frequencies such as 8.35 GHz may be used.

  The overall operation of the plasma processing apparatus 42 formed in this way is controlled by a control means 116 made of, for example, a microcomputer, and a computer program for performing this operation is a flexible disk or a CD ( (Compact Disc) and a storage medium 118 such as a flash memory. Specifically, supply of each gas and flow control, supply of microwaves and high frequencies, power control, control of process temperature and process pressure, and the like are performed according to commands from the control means 116.

Next, an example of a processing method performed using the plasma processing apparatus 42 configured as described above will be described.
First, the gate valve 52 is opened, the semiconductor wafer W is accommodated in the processing container 44 by the transfer arm (not shown) via the loading / unloading port 50 for the object to be processed, and the lift pins 64 are moved up and down to move the wafer W. Is mounted on the mounting surface on the upper surface of the mounting table 46, and the wafer W is electrostatically attracted by the electrostatic chuck 80. The wafer W is maintained at a predetermined process temperature by the heating unit 72 when necessary, and is supplied into the processing container 44 from the gas nozzle 54A of the gas introduction unit 54 while controlling the flow rate of a predetermined gas supplied from a gas source (not shown). Then, the pressure control valve 58 is controlled to maintain the inside of the processing container 44 at a predetermined process pressure.

  At the same time, by driving the microwave generator 114 of the microwave introducing device 92, the microwave generated by the microwave generator 114 is fed via the rectangular waveguide 112 and the coaxial waveguide 108. The microwave which is supplied from the unit 100 to the planar antenna member 94 and the slow wave member 98 and whose wavelength is shortened by the slow wave member 98 is transmitted through the top plate 88 and introduced into the processing space S. A plasma is generated and a predetermined process using the plasma is performed.

  Here, the propagation of the microwave from the lower end portion of the coaxial waveguide 108 will be described in more detail. The microwave propagated through the coaxial waveguide 108 is a convex shape provided in the central portion of the slow wave member 98. And propagates radially toward the periphery of the slow wave member 98 and the planar antenna member 94, and microwaves are radiated toward the processing spaces S below the slots 96 during the propagation. To be introduced into the container.

  At this time, the convex power supply portion 100 has a side wall substantially perpendicular to the upper surface of the slow wave member 98 so that the processing is easy, so that the power supply portion 100 is formed. Dimensional accuracy can be increased in polishing or the like. For example, the accuracy of the conventional power supply unit 100 having a tapered surface (26 in FIG. 8) is about ± 0.5 mm, but in the present invention, it can be reduced to about ± 0.1 mm. Therefore, as shown in FIGS. 2 and 3, the convex feeding portion 100 is fitted to the lower end side of the outer conductor 108 </ b> B of the coaxial waveguide 108 with high dimensional accuracy. Unlike the conventional device shown in FIG. 7, there is almost no gap between the side wall 100A and the inner wall surface of the outer conductor 108B of the coaxial waveguide 108, and the generation of this gap can be suppressed.

In other words, the side wall of the convex feeding portion 100 that feeds power from the coaxial waveguide 108 is formed so as to be perpendicular to the plane direction of the slow wave member 98 so as to be perpendicular. As a result, processing such as polishing is facilitated, and dimensional accuracy during processing can be improved.
Accordingly, it is possible to suppress the occurrence of a gap between the power feeding unit 100 and the inner diameter of the waveguide box 104 or the coaxial waveguide 108 that covers the power supply unit 100. Therefore, it is possible not only to prevent abnormal discharge from occurring in this part. Further, it is possible to prevent the symmetry of the electric field distribution in the planar antenna member 94 from being broken.

Moreover, since generation | occurrence | production of a clearance gap can be suppressed as mentioned above, it can set to the characteristic impedance as designed, and the reflectance of a microwave can be suppressed.
Furthermore, when the cooling means 106 is provided, the gap between the inner wall surface of the coaxial waveguide 108 provided with the cooling means 106 or the inner wall surface of the waveguide box and the power feeding unit 100 can be suppressed. The thermal conductivity of this part is improved, and the cooling efficiency of the power feeding unit can be improved.

  Further, in the present invention, since the side wall 100A of the power feeding unit 100 is formed so as to stand upright from the surface of the slow wave member 98, the conventional power feeding unit 26 having a tapered side wall (see FIGS. 7 and 7). 8), the change in characteristic impedance is too rapid, which may increase the reflectance of the microwave. However, by optimizing the height H1 of the power supply unit 100, the reflectance of the microwave is also reduced. can do.

  This optimized height H1 is in the range of about 6.5 to 8.5 mm when the material of the slow wave member 98 and the power feeding unit 100 is alumina having a relative dielectric constant of about 9.8. In the case of quartz having a dielectric constant of about 3.8, it is in the range of about 11.0 to 13.0 mm. Thus, by optimizing the height H1 of the power feeding unit 100, the reflectance of the microwave can be suppressed, and this can be reduced to 5% or less.

<Change in characteristic impedance and reflectivity>
Here, a change in characteristic impedance in the slow wave member 98 of the microwave introducing device according to the present invention was obtained, and the height of the power feeding unit with respect to the reflectivity was optimized. FIG. 4 is a diagram schematically showing the dimensions of the respective portions in the central portion of the slow wave member when obtaining the characteristic impedance, and FIG. 5 is a graph showing the relationship between the height of the feeding portion of the slow wave member and the reflectance of the microwave. is there. Here, the frequency of the microwave is set to 2.45 GHz, but this frequency is not particularly limited.

  FIG. 4A shows a conventional power feeding portion of the slow wave member, and FIG. 4B shows a power feeding portion of the slow wave member of the present invention. Here, the slow wave member is made of alumina having a relative dielectric constant of 9.8, and the thickness d is set to 4 mm. The radius d1 of the through hole of each power feeding portion is set to 8.45 mm, and the radius d2 of the power feeding portion is set to 19.4 mm. 4A is set to 6 mm, and the power supply height H1 shown in FIG. 4B is set to 8 mm. The characteristic impedance of the coaxial waveguide is set to 50Ω.

Here, the characteristic impedance Z is given by the following equation.
Z = V / I = 60d / (r√ε)
r: Distance from the center of the slow wave member ε: Dielectric constant As a result, in the case of the conventional slow wave member shown in FIG. 4A, the characteristic impedance is at the boundary between the coaxial waveguide and the feeding portion. It was 15.9Ω, 7.4Ω at the taper portion in the middle of the power feeding portion, and 1.5Ω at the vertical portion at the end of the power feeding portion. At this time, the reflectance of the microwave was about 4.5%.

  On the other hand, in the case of the present invention shown in FIG. 4B, the characteristic impedance is 15.9Ω at the boundary between the coaxial waveguide and the feeding portion, 10Ω at the end of the feeding portion and the diagonal portion, It was 3.95Ω at the end of the power feeding part and the vertical part. At this time, the reflectance of the microwave was about 3.6%, and it was confirmed that it was able to be significantly suppressed from 4.5% of the conventional device.

  Here, in the slow wave member 98 according to the present invention illustrated in FIG. 4B, the dependence of the microwave reflectance on the height H <b> 1 of the power feeding unit 100 was examined. The result is shown in FIG. As shown in FIG. 5A, here, the height H1 is changed from 6 to 9 mm, and the reflectance has a convex characteristic curve. When the height H1 is 8 mm, the reflectivity is about 3.5, indicating the minimum value. And when the upper limit of the reflectance was 5%, it was confirmed that the range with the height H1 of 6.5 to 8.5 mm was the optimum range. More preferably, in order to make the reflectance 4% or less, it was confirmed that it is preferable to set the height H1 within the range of 7.0 to 8.1 mm.

  As described above, when the plasma state actually generated for the plasma processing apparatus is verified using the slow wave member in which the height H1 of the power supply unit 100 is set to 8 mm, the microwave power is changed to 1000 to 3500 watts. In addition, it was confirmed by visual observation that plasma can be stably formed even when the pressure in the container is changed within the range of 50 to 200 mTorr.

In addition, the same examination as described above was performed by changing the material from alumina to quartz. FIG. 5B shows the relationship between the height H1 of the power feeding unit and the reflectance at this time. Incidentally, the thickness d of the slow wave member made of quartz is 7 mm, and the relative dielectric constant ε of this quartz is 3.8.
As is clear from FIG. 5 (B), to maintain a microwave reflectance of 5% or less, confirm that it is preferable to set the height H1 within the range of 11.0 to 13.0 mm. I was able to. Since the relative dielectric constant of aluminum nitride (AlN) is about 8.0, it is substantially the same as the above alumina, and the above dimensions obtained with alumina can be applied to aluminum nitride.

The configuration of the plasma processing apparatus is merely an example, and is not limited to this. The material and relative dielectric constant of the slow wave member 98 are merely examples, and are not limited thereto. In particular, the height H1 of the power supply unit 100 is naturally optimized in accordance with the relative dielectric constant of the material used.
Although the semiconductor wafer is described as an example of the object to be processed here, the present invention is not limited thereto, and the present invention can be applied to a glass substrate, an LCD substrate, a ceramic substrate, and the like.

It is a block diagram which shows an example of the plasma processing apparatus using the microwave introduction apparatus which concerns on this invention. It is an enlarged view which shows the center part of the planar antenna member and slow wave member in the microwave introduction apparatus of this invention. It is a perspective view which shows the center part of a slow wave member. It is a figure which shows typically the dimension of each part in the center part of the slow wave member at the time of calculating | requiring characteristic impedance. It is a graph which shows the relationship between the height of the electric power feeding part of a slow wave member, and the reflectance of a microwave. It is a schematic block diagram which shows the conventional general plasma processing apparatus. It is an enlarged view which shows the center part of a planar antenna member and a slow wave member. It is a perspective view which shows the center part of a slow wave member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 42 Plasma processing apparatus 44 Processing container 46 Mounting stand 54 Bus introduction means 88 Top plate 92 Microwave introduction means 94 Planar antenna member 96 Slot 98 Slow wave member 100 Feed part 100A Side surface 102 Through-hole 104 Waveguide box 106 Cooling jacket (cooling means) )
108 Coaxial waveguide 108A Center conductor 108B Outer conductor 112 Rectangular waveguide 114 Microwave generator W Semiconductor wafer (object to be processed)

Claims (10)

A microwave generator for generating microwaves;
A planar antenna member formed with slots for microwave radiation;
A waveguide for propagating the microwave generated by the microwave generator to the planar antenna member;
A flat plate-like slow wave member that is provided so as to overlap with the planar antenna member and has a convex feeding portion that feeds power from the waveguide at the center, thereby shortening the wavelength of the propagating microwave. When,
In a microwave introduction device having
The waveguide has a coaxial waveguide composed of a central conductor and an outer conductor, and the central conductor is connected to the central portion of the planar antenna member through a through hole formed in the feeding portion. The microwave introduction device is characterized in that a side wall of the convex feeding portion is formed to stand substantially perpendicular to a plane direction of the slow wave member. The microwave introduction device according to claim 1, wherein the slow wave member is made of a dielectric. 3. The microwave introduction device according to claim 1, wherein a height of the convex feeding portion from an upper surface of the slow wave member is set in a range of 6.5 to 13.0 mm. 4. The microwave introducing device according to claim 3, wherein the slow wave material is made of alumina, and a height of the convex feeding portion is set in a range of 6.5 to 8.5 mm. 4. The microwave introducing device according to claim 3, wherein the slow wave material is made of quartz, and the height of the convex feeding portion is set in a range of 11 to 13 mm. 6. The microwave introduction device according to claim 1, wherein the slow wave member is covered with a waveguide box made of a conductive material. The microwave introducing device according to claim 6, wherein the wave guide box is provided with a cooling means for cooling the slow wave member. The microwave introducing device according to any one of claims 1 to 7, wherein the microwave is 2.45 GHz or 8.35 GHz. A processing vessel in which the ceiling is opened and the inside can be evacuated;
A mounting table provided in the processing container for mounting the object to be processed;
A top plate made of a dielectric material that is airtightly attached to the opening of the ceiling portion and transmits microwaves;
Gas introducing means for introducing a necessary processing gas into the processing container;
The microwave introduction device according to any one of claims 1 to 8, provided on the top plate side for introducing microwaves into the processing container;
A plasma processing apparatus comprising: The plasma processing apparatus according to claim 9, wherein the top plate and the slow wave member are made of the same material.

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