KR101722307B1 - Microwave irradiating antenna, microwave plasma source, and plasma processing device - Google Patents

Abstract

The microwave radiation antenna 45 for radiating the microwave transmitted through the microwave transmission path into the chamber to generate the surface wave plasma includes an antenna main body 121 made of a conductor and a plurality of And a plurality of gas discharging holes 125 for discharging a process gas into the chamber provided in the antenna main body 121. A metal surface wave is formed on the surface by a microwave, A dielectric layer 126 is provided so that a plasma is generated and at least a part of the metal surface of the antenna main body 121 is directly insulated from the surface wave plasma.

Description

TECHNICAL FIELD [0001] The present invention relates to a microwave radiation antenna, a microwave plasma source, and a plasma processing apparatus. [0002] MICROWAVE IRRADIATING ANTENNA, MICROWAVE PLASMA SOURCE, AND PLASMA PROCESSING DEVICE [

The present invention relates to a microwave radiation antenna, a microwave plasma source, and a plasma processing apparatus.

Plasma processing is an indispensable technique for manufacturing semiconductor devices. However, in recent years, due to the demand for high integration and speeding up of LSIs, design rules for semiconductor devices constituting LSIs have been getting smaller and semiconductor wafers have become larger, In the processing apparatus, it is required to cope with such miniaturization and enlargement.

However, in the parallel plate type or inductively coupled plasma processing apparatus which has been widely used, plasma damage is generated in the fine elements because the electron temperature of generated plasma is high, and a region having a high plasma density is limited, It is difficult to uniformly process the semiconductor wafer at a high speed.

Therefore, a RLSA (Radial Line Slot Antenna) microwave plasma processing apparatus capable of uniformly forming a surface wave plasma of a low electron temperature at a high density has been attracting attention (for example, Patent Document 1).

The RLSA microwave plasma processing apparatus is a microwave radiation antenna that emits a microwave for generating a surface wave plasma, and is provided with a radial line slot antenna that is a planar slot antenna having a plurality of slots formed in a predetermined pattern on an upper part of the chamber , A microwave derived from a microwave generating source is radiated from a slot of an antenna and is radiated into a vacuum maintained chamber through a microwave transmitting plate including a dielectric provided thereunder, and the microwave electric field causes a surface wave plasma Thereby processing an object to be processed such as a semiconductor wafer.

In addition, a plurality of microwave radiating units having a planar slot antenna, which is a microwave radiating antenna as described above, are provided, and a microwave radiated from the flat slot antenna is guided into the chamber to space- (Refer to Patent Document 2).

Japanese Patent Application Laid-Open No. 2000-294550 International Publication No. 2008/013112 pamphlet

However, in the processing apparatuses described in Patent Documents 1 and 2, the microwave is introduced from the ceiling wall of the chamber, whereas the processing gas is supplied from the side wall of the chamber or the shower plate provided in the chamber. However, in these cases, it is difficult to control the gas flow. In addition, although the shower plate is inevitably formed of quartz having plasma resistance, since quartz is permeated through the microwave, the gas is converted into plasma at the gas hole of the shower plate, resulting in loss of microwave power or abnormal discharge.

In order to prevent such a problem, it is conceivable that the microwave radiation antenna made of metal (conductor) is made into a shower structure having gas holes, and microwave and gas are introduced from the same part. In this case, since the gas is radiated from the microwave radiation antenna made of metal, the gas can be discharged without being influenced by the microwave by the presence of the shower plate, so that the surface acoustic wave plasma can be formed on the surface of the plane slot antenna.

However, when the surface radiating the microwave is metal, it has been found that the plasma concentrates around the slot and emits light, resulting in the uniformity in the diameter direction being disturbed.

Accordingly, it is an object of the present invention to provide a microwave radiation antenna, a microwave plasma source, and a plasma processing apparatus which can supply a microwave and a processing gas from a microwave radiation antenna and form a surface wave plasma with high uniformity on the surface thereof.

That is, according to a first aspect of the present invention, there is provided a plasma processing apparatus for forming a surface wave plasma in a chamber and performing plasma processing, the plasma processing apparatus comprising: a microwave radiation antenna for radiating a microwave transmitted through a microwave transmission path, A plurality of slots provided in the antenna main body for radiating microwaves and a plurality of gas discharge holes provided in the antenna main body for discharging a process gas into the chamber, There is provided a microwave radiation antenna in which a surface acoustic wave is formed on a surface thereof and a surface acoustic wave plasma is generated by the surface acoustic wave so that at least a part of the metal surface of the antenna body is insulated from the surface acoustic wave plasma.

In the first aspect, at least a part of the surface of the antenna main body can be insulated by covering it with a dielectric layer having a thickness that can sustain a surface acoustic wave. In this case, it is preferable that the thickness of the dielectric layer is not more than? / 7 when the wavelength of the microwave in vacuum is?.

The dielectric layer may be a film formed by a film forming technique or may be formed of a thin dielectric plate. In the case of using a dielectric thin plate, it is preferable that the dielectric thin plate has a metal film having a pattern except for the slot and the gas discharge hole on a part of the surface facing the antenna main body. In this case, it is preferable that the plurality of slots are arranged in a columnar shape on the surface of the antenna main body, and the metal film is set in a range of the position corresponding to the outer diameter of the slot from the center of the dielectric thin plate . Further, the antenna main body may be DC insulated from the chamber.

According to a second aspect of the present invention, there is provided a microwave plasma source for generating a surface wave plasma by radiating a microwave into a chamber of a plasma processing apparatus, comprising: a microwave output unit for generating and outputting a microwave; Wherein the microwave supply unit includes a transmission line for transmitting the microwave outputted from the microwave output unit and a microwave radiation antenna for radiating the microwave into the chamber, A plurality of slots provided in the antenna main body for radiating microwaves and a plurality of gas discharge holes provided in the antenna main body for discharging a process gas into the chamber, The metal surface wave is formed on the surface, is a surface wave plasma is generated by the metal surface wave, at least, the microwave plasma source part is configured such that from the surface wave to the direct-current plasma isolated enemy of the metal surface of the antenna main body is provided.

According to a third aspect of the present invention, there is provided a plasma processing apparatus comprising: a chamber accommodating a substrate to be processed; a gas supply mechanism for supplying a process gas; and a microwave plasma source for radiating a microwave into the chamber to form a surface wave plasma, And a microwave supply unit for supplying the microwave output from the microwave output unit into the chamber, wherein the microwave supply unit is a transmission unit for transmitting microwave output from the microwave output unit, And a microwave radiating antenna for radiating a microwave into the chamber, wherein the microwave radiating antenna comprises: an antenna body made of a conductor; a plurality of slots provided in the antenna body for radiating a microwave; And a plurality of gas discharge holes for discharging a process gas into the chamber, wherein a surface acoustic wave is formed by the microwave, a surface acoustic wave plasma is generated by the surface wave, and at least a part of the metal surface And a surface acoustic wave generated by the gas supplied from the gas supply mechanism by a surface acoustic wave formed on the surface of the microwave radiation antenna by the microwave supplied into the chamber from the microwave plasma source, There is provided a plasma processing apparatus for generating a plasma and performing processing by plasma on a substrate to be processed in the chamber.

In the second and third aspects, the microwave supply unit may have a plurality of the microwave radiation antennas.

1 is a cross-sectional view showing a schematic configuration of a plasma processing apparatus having a microwave plasma source having a microwave radiation antenna according to an embodiment of the present invention.
2 is a configuration diagram showing a configuration of a microwave plasma source used in the plasma processing apparatus of FIG.
3 is a plan view schematically showing a microwave supply unit in a microwave plasma source.
FIG. 4 is a longitudinal sectional view showing a microwave radiating section including a microwave radiating antenna, which is used in the plasma processing apparatus of FIG. 1;
5 is a cross-sectional view taken along the line AA 'in Fig. 4 showing a feeding mechanism of the microwave radiating section.
Fig. 6 is a cross-sectional view taken along the line BB 'in Fig. 4 showing the slug and the sliding member in the tuner.
FIG. 7 is a cross-sectional view taken along line CC 'of FIG. 4 showing the interior of the microwave radiation antenna.
8 is a plan view showing an example of the shape and arrangement of slots of a microwave radiation antenna.
9 is a diagram showing a difference in sheath thickness between a slot portion and a portion other than the slot when the surface of the microwave radiation antenna is a metal (conductor).
Fig. 10 is a diagram showing the thickness of the jacket at the slot portion and the slot portion when the dielectric layer is provided on the surface of the microwave radiation antenna.
11 is a diagram showing the state of the surface wave plasma in the case where the dielectric layer is not formed in the antenna main body of the microwave radiation antenna and in the case where the dielectric layer is formed.
12 is a diagram showing the distribution of the electron density when the dielectric layer is not formed on the antenna main body of the microwave radiating antenna and when the dielectric layer is formed.
13 is a diagram showing the distribution of the electron density normalized by the electron density at the position where the distance in the radial direction in FIG. 12 is zero.
14 is a view for explaining a mechanism in which an abnormal discharge occurs in a gap between an antenna main body and a dielectric thin plate when a dielectric thin plate is used as a dielectric layer.
Fig. 15 is a diagram showing the electric field distribution in the gap between the antenna main body and the dielectric thin plate obtained by electromagnetic field simulation. Fig.
Fig. 16 is a diagram showing the distribution of electric fields in the gap between the antenna main body and the dielectric thin plate obtained by electromagnetic field simulation when a metal film is coated on the entire surface of the dielectric thin plate facing the antenna main body.
17 is a diagram schematically showing a state in which a metal film formed on a dielectric thin plate is formed as an inner region of a slot of a dielectric thin plate.
Fig. 18 is a diagram showing the electric field distribution in the gap between the antenna main body and the dielectric thin plate obtained by electromagnetic field simulation in the case of using the thin dielectric plate having the metal film formed in the state of Fig. 17;
19 is a diagram schematically showing a state in which a metal film formed on a dielectric thin plate is aligned with an inner region of a slot of a dielectric thin plate and an outermost periphery of the metal thin film is aligned with an outer diameter of the slot.
Fig. 20 is a diagram showing the electric field distribution in the gap between the antenna main body and the dielectric thin plate obtained by electromagnetic field simulation in the case of using the thin dielectric plate having the metal film formed in the state of Fig. 19;
21 is a cross-sectional view showing an example of a microwave radiation antenna preferable when a dielectric thin plate is provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

≪ Configuration of Plasma Processing Apparatus >

Fig. 1 is a cross-sectional view showing a schematic configuration of a plasma processing apparatus having a microwave plasma source having a microwave radiation antenna according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of a microwave plasma source used in the plasma processing apparatus of Fig. FIG. 3 is a plan view schematically showing a microwave supply unit in a microwave plasma source, FIG. 4 is a sectional view showing a microwave radiating unit including a microwave radiation antenna in a microwave plasma source, and FIG. 5 Fig. 6 is a cross-sectional view taken along the line BB 'of Fig. 4 showing the slag and the sliding member in the tuner of the microwave radiating section, Fig. 7 is a cross- 4, showing the microwave irradiation antenna of the radiating part A cross-sectional view.

The plasma processing apparatus 100 is constituted as a plasma etching apparatus for performing, for example, an etching process on a wafer, and includes a substantially cylindrical grounded chamber made of a metallic material such as aluminum or stainless steel, (1) and a microwave plasma source (2) for forming a microwave plasma in the chamber (1). An opening 1a is formed in the upper part of the chamber 1 and the microwave plasma source 2 is provided so as to face the inside of the chamber 1 from the opening 1a.

A susceptor 11 for horizontally supporting a semiconductor wafer W (hereinafter referred to as a wafer W) to be processed is disposed within the chamber 1 and an insulating member 12a is provided at the center of the bottom of the chamber 1. [ And is supported by a tubular support member 12 installed upright through a through-hole. Examples of the material constituting the susceptor 11 and the supporting member 12 include aluminum obtained by anodizing the surface (anodizing treatment), ceramics such as AlN, and the like.

Although not shown, the susceptor 11 is provided with an electrostatic chuck for electrostatically attracting the wafer W, a temperature control mechanism, a gas flow path for supplying a heat transfer gas to the back surface of the wafer W, And a lifting pin for lifting and lowering the lifting pin to transport the lifting pin. A high frequency bias power supply 14 is electrically connected to the susceptor 11 through the matching unit 13. [ High frequency power is supplied from the high frequency bias power supply 14 to the susceptor 11, so that ions in the plasma are attracted to the wafer W side. The high-frequency bias power supply 14 may not be provided depending on the characteristics of the plasma processing.

An exhaust pipe 15 is connected to the bottom of the chamber 1 and an exhaust device 16 including a vacuum pump is connected to the exhaust pipe 15. By operating the exhaust device 16, the chamber 1 is evacuated, and the inside of the chamber 1 can be depressurized to a predetermined degree of vacuum at high speed. A loading and unloading port 17 for loading and unloading the wafer W and a gate valve 18 for opening and closing the loading and unloading port 17 are provided on the side wall of the chamber 1.

The microwave plasma source 2 is provided on a ceiling plate 85 supported by a support ring 29 provided on the upper portion of the chamber 1. [ The space between the support ring (29) and the ceiling plate (85) is hermetically sealed.

The microwave plasma source 2 includes a microwave output unit 30 for distributing microwaves to a plurality of paths and a microwave supply unit 40 for transmitting the microwaves output from the microwave output unit 30 and radiating the microwaves into the chamber 1, . The microwave plasma source 2 also has a gas supply source 110 for supplying a plasma generation gas for generating a plasma and a process gas for performing a film formation process and an etching process.

As the plasma generating gas, a rare gas such as Ar gas can be suitably used. As the process gas, various processes can be employed depending on the content of the process such as a film forming process or an etching process.

2, the microwave output section 30 includes a microwave power source 31, a microwave oscillator 32, an amplifier 33 for amplifying the oscillated microwave, a distributor (Not shown).

The microwave oscillator 32 oscillates the PLL by using a microwave of a predetermined frequency (for example, 915 MHz) as an example. The distributor 34 distributes the amplified microwaves to the amplifier 33 while taking impedance matching between the input side and the output side so that the loss of the microwaves does not occur as much as possible. As the frequency of the microwave, in addition to 915 MHz, 700 MHz to 3 GHz can be used.

The microwave supply unit 40 has a plurality of antenna modules 41 for guiding the microwave distributed by the distributor 34 into the chamber 1. Each antenna module 41 has an amplifier section 42 for mainly amplifying the distributed microwave and a microwave radiating section 43. The microwave radiating section 43 includes a microwave transmission line 44 provided with a tuner 60 for matching impedance and an antenna 45 radiating the amplified microwave into the chamber 1 I have. Microwave is radiated into the chamber 1 from the antenna 45 of the microwave radiating section 43 of each antenna module 41. [ 3, the microwave supply unit 40 has seven antenna modules 41, and the microwave radiating parts 43 of the respective antenna modules 41 are arranged in the shape of six cylinders and one And is disposed in a circular top plate 85 which is circular.

The antenna 45 has a shower structure for discharging a plasma generation gas and a processing gas as described later and a gas piping 111 extending from the gas supply source 110 is connected to the antenna 45. The plasma generated gas introduced into the chamber 1 from the antenna 45 is converted into plasma by the microwave radiated from the antenna 45 and is similarly introduced into the chamber 1 from the antenna 45 And the plasma of the process gas is generated.

The amplifier section 42 has the above-mentioned 46, the variable gain amplifier 47, the main amplifier 48 constituting the solid state amplifier, and the isolator 49.

The above-mentioned (46) is configured to change the phase of the microwave, and the radiation characteristic can be modulated by adjusting the phase. For example, the directivity can be controlled by adjusting the phase for each antenna module to change the plasma distribution. In addition, circularly polarized waves can be obtained by shifting the phase by 90 degrees in the neighboring antenna module. In addition, the above-mentioned (46) can be used for the purpose of spatial synthesis in the tuner by adjusting delay characteristics between components in the amplifier. However, in the case where the modulation of the radiation characteristic and the adjustment of the delay characteristics between the components in the amplifier are unnecessary, the above-mentioned (46) need not be provided.

The variable gain amplifier 47 is an amplifier for adjusting the deviation of individual antenna modules or adjusting the plasma intensity by adjusting the power level of the microwave inputted to the main amplifier 48. [ By varying the variable gain amplifier 47 for each antenna module, it is also possible to generate a distribution in the generated plasma.

The main amplifier 48 constituting the solid state amplifier may have, for example, an input matching circuit, a semiconductor amplification element, an output matching circuit, and a high-Q resonance circuit.

The isolator 49 separates the reflection microwave reflected from the antenna 45 toward the main amplifier 48 and has a circulator and a dummy rod (coaxial terminator). The circulator induces the microwave reflected from the antenna 45 to the dummy rod, and the dummy rod converts the reflected microwave induced by the circulator into heat.

Next, the microwave radiating section 43 will be described in detail with reference to Figs. 4 to 7. Fig.

4, the microwave radiating section 43 includes a coaxial waveguide (microwave transmission path) 44 for transmitting a microwave and a microwave transmission path 44 for radiating the transmitted microwave into the chamber 1 And an antenna 45 for transmitting and receiving signals. The microwave radiated from the antenna 45 into the chamber 1 is synthesized in the space in the chamber 1 so that the surface wave plasma is formed in the chamber 1.

The microwave transmission path 44 is formed by coaxially arranging a tube-shaped outer conductor 52 and a rod-shaped inner conductor 53 provided at the center of the tubular outer conductor 52. The microwave transmission path 44 has an antenna 45 ). In the microwave transmission path 44, the inner conductor 53 is fed and the outer conductor 52 is grounded. A reflector 58 is provided on the upper end of the outer conductor 52 and the inner conductor 53.

On the base end side of the microwave transmission path 44, there is provided a power supply mechanism 54 for supplying a microwave (electromagnetic wave). The power supply mechanism 54 has a microwave power introduction port 55 for introducing microwave power provided on the side surface of the microwave transmission path 44 (outer conductor 52). A coaxial line 56 including an inner conductor 56a and an outer conductor 56b is connected to the microwave power introduction port 55 as a feed line for feeding the microwave amplified from the amplifier section 42. [ A feed antenna 90 extending horizontally toward the inside of the outer conductor 52 is connected to the tip of the inner conductor 56a of the coaxial line 56. [

The feed antenna 90 is formed by, for example, cutting a metal plate such as aluminum and then sandwiching the die member of a dielectric member such as Teflon (registered trademark). A slow-wave member 59 including a dielectric such as Teflon (registered trademark) for shortening the effective wavelength of the reflected wave is provided between the reflection plate 58 and the feed antenna 90. In the case of using a microwave having a high frequency such as 2.45 GHz, the trench material 59 may not be provided. At this time, by optimizing the distance from the feeding antenna 90 to the reflection plate 58 and reflecting the electromagnetic wave radiated from the feeding antenna 90 to the reflection plate 58, the maximum electromagnetic wave is transmitted through the microwave transmission path 44 of the coaxial structure, Lt; / RTI >

The feed antenna 90 is connected to the inner conductor 56a of the coaxial line 56 in the microwave power introduction port 55 as shown in Fig. 5 which is a sectional view taken along the line AA 'in Fig. 4, An antenna main body 91 having a first pole 92 and a second pole 93 for radiating a supplied electromagnetic wave and a second pole 93 extending from the both sides of the antenna main body 91 along the outer side of the inner conductor 53, And a standing wave is formed by the electromagnetic wave incident on the antenna main body 91 and the electromagnetic wave reflected by the reflecting portion 94. [ The second pole 93 of the antenna main body 91 is in contact with the inner conductor 53.

Microwave power is supplied to the space between the outer conductor 52 and the inner conductor 53 by radiating the microwave (electromagnetic wave) by the feeding antenna 90. [ Then, the microwave power supplied to the power feeding mechanism 54 is propagated toward the antenna 45.

Further, the microwave transmission path 44 is provided with a tuner 60. The tuner 60 matches the impedance of the load (plasma) in the chamber 1 with the characteristic impedance of the microwave power source in the microwave output section 30. The tuner 60 adjusts the impedance of the microwave power between the outer conductor 52 and the inner conductor 53 Two slags 61a and 61b for vertically moving the transfer path 44 and a slug driving part 70 provided on the outside (upper side) of the reflection plate 58. [

Of these slag, the slag 61a is provided on the slag driving part 70 side, and the slag 61b is provided on the antenna 45 side. The inner space of the inner conductor 53 is provided with two slag moving shafts 64a and 64b for moving the slag including a screw rod provided with a trapezoidal screw, for example along the longitudinal direction.

6, which is a sectional view taken along the line BB 'of FIG. 4, the slag 61a has an annular shape including a dielectric, and a sliding member 63 including a resin having slidability is embedded in the slag 61a . The slide member 63 is formed with a screw hole 65a to which the slag moving shaft 64a is screwed and a through hole 65b through which the slag moving shaft 64b is inserted. On the other hand, the slag 61b has the screw hole 65a and the through hole 65b as in the case of the slag 61a. In contrast to the slag 61a, the screw hole 65a is screwed to the slag moving shaft 64b And the slug moving shaft 64a is inserted through the through hole 65b. Thus, the slag 61a is moved up and down by rotating the slag moving shaft 64a, and the slag 61b is moved up and down by rotating the slag moving shaft 64b. That is, the slugs 61a and 61b are moved up and down by the screw mechanism including the slug moving shafts 64a and 64b and the sliding member 63. [

Three slits 53a are formed in the inner conductor 53 at regular intervals along the longitudinal direction. On the other hand, in the sliding member 63, three projections 63a are provided at equal intervals so as to correspond to these slits 53a. The sliding member 63 is fitted into the slag 61a and 61b in a state in which the projecting portion 63a is in contact with the inner periphery of the slag 61a and 61b. The outer circumferential surface of the sliding member 63 makes contact with the inner circumferential surface of the inner conductor 53 without loosening and the sliding member 63 slides on the inner conductor 53 by the rotation of the slug moving shafts 64a and 64b, . That is, the inner circumferential surface of the inner conductor 53 functions as a sliding guide of the slag 61a, 61b.

As a resin material constituting the sliding member 63, a resin having good slidability and comparatively easy to work, for example, a polyphenylene sulfide (PPS) resin, is preferably used.

The slag moving shafts 64a and 64b extend through the reflector 58 and extend to the slag driving unit 70. A bearing (not shown) is provided between the slag moving shafts 64a and 64b and the reflecting plate 58. [ A bottom plate 67 including a conductor is provided at the lower end of the inner conductor 53. The lower ends of the slag moving shafts 64a and 64b are generally open ends to absorb vibration during driving and are separated from the lower ends of the slag moving shafts 64a and 64b by about 2 to 5 mm, ) Is installed. Alternatively, the bottom plate 67 may be a bearing portion, and the lower end portions of the slag moving shafts 64a and 64b may be axially supported by the bearing portion.

The slag driving part 70 has a housing 71. The slag moving shafts 64a and 64b extend into the housing 71. Gears 72a and 72b are provided at the upper ends of the slag moving shafts 64a and 64b, Is installed. The slag driving unit 70 is provided with a motor 73a for rotating the slag moving shaft 64a and a motor 73b for rotating the slag moving shaft 64b. A gear 74a is provided on the shaft of the motor 73a and a gear 74b is provided on the shaft of the motor 73b so that the gear 74a is engaged with the gear 72a, (72b). Therefore, the slag moving shaft 64a is rotated by the motor 73a through the gears 74a and 72a, and the slag moving shaft 64b is rotated by the motor 73b through the gears 74b and 72b. The motors 73a and 73b are, for example, stepping motors.

The positions of the gears 72a and 72b are offset vertically and the motors 73a and 73b are also vertically shifted up and down The space of the power transmission mechanism such as the motor and the gear is small and the housing 71 has the same diameter as the outer conductor 52. [

On the motors 73a and 73b are provided incremental encoders 75a and 75b for detecting the positions of the slag 61a and 61b, respectively, so as to be directly connected to these output shafts.

The positions of the slag 61a and 61b are controlled by the slag controller 68. Specifically, based on the impedance value of the input end detected by an impedance detector (not shown) and the position information of the slag 61a and 61b detected by the encoders 75a and 75b, the slag controller 68 controls the motor A control signal is sent to the slabs 73a and 73b, and the position of the slag 61a and 61b is controlled to adjust the impedance. The slag controller 68 performs impedance matching so that the terminal portion is, for example, 50 OMEGA. If you move only one of the two slats, you will see the trajectory through the origin of the Smith chart, and if you move both of them simultaneously, only the phase will rotate.

The antenna 45, which is a microwave radiation antenna, is formed as a planar slot antenna having a plane shape. A trench material 82 is provided on the upper surface of the antenna 45. A cylindrical member 82a including a conductor passes through the center of the trench material 82. The cylindrical member 82a connects the bottom plate 67 and the antenna 45. [ Therefore, the inner conductor 53 is connected to the antenna 45 through the bottom plate 67 and the cylindrical member 82a. The lower end of the outer conductor 52 extends to the antenna 45 and the periphery of the waveguide material 82 is covered with the outer conductor 52.

The trench material 82 has a larger dielectric constant than that of vacuum, and is made of, for example, a fluorine resin such as quartz ceramics or polytetrafluoroethylene, or a polyimide resin. This is because in order to shorten the wavelength of the microwave and reduce the size of the antenna because the wavelength of the microwave is long in vacuum. The trench material 82 can adjust the phase of the microwave according to its thickness and adjust its thickness so that the surface of the antenna 45 (microwave emitting surface) becomes " antinode " of the standing wave. Thereby, the reflection can be minimized and the radiant energy of the microwave can be maximized.

4, the antenna 45 includes an antenna main body 121 having a hollow disc shape and a microwave transmission path 44 formed in the antenna main body 121, A gas diffusion space 123 formed in the interior of the antenna main body 121 and a gas introduction port 124 for introducing a plasma generation gas or a process gas into the gas diffusion space 123 A plurality of gas discharge holes 125 extending from the gas diffusion space 123 to face the chamber 1 and a dielectric layer 126 formed on the microwave radiation plane of the antenna main body 121. An O-ring (not shown) is interposed between the trench material 82 and the antenna main body 121.

The antenna main body 121 is formed of a conductor. As the conductor constituting the antenna main body 121, a metal having a high electrical conductivity such as aluminum or copper is preferable. The antenna main body 121 has an upper wall 121a, a side wall 121b, and a bottom wall 121c.

The gas inlet 124 is provided on the outer peripheral side of the slot 122 of the upper wall 121a and connected to a gas pipe 111 extending from the gas supply source 110, A plasma generation gas such as Ar supplied to the piping 111 and a process gas such as a fluorocarbon gas such as C ₄ F ₈ are introduced into the gas diffusion space 123 through the gas introduction port 124. The gas discharge hole 125 is formed in the bottom wall 121c so as to discharge the gas introduced into the gas diffusion space 123 into the chamber 1. [

The slot 122 has an upper portion 122A formed through the gas diffusion space 123 from the upper wall 121a and a lower portion 122B formed through the bottom wall 121c. As shown in Fig. 7, which is a cross-sectional view taken along the line CC 'in Fig. 4, at a portion corresponding to the gas diffusion space 123 in the upper portion 122A of the slot 122, (127) are formed. Thereby, the microwave passing through the slot 122 and the gas flowing in the gas diffusion space 123 are separated from each other, so that generation of plasma in the antenna 45 is avoided.

A stepped portion to be described later is formed between the upper portion 122A and the lower portion 122B. The slot 122 may be filled with a dielectric. By filling the slot 122 with a dielectric, the effective wavelength of the microwave is shortened, so that the thickness of the entire slot (the thickness of the antenna main body 121) can be reduced.

The shape of the slot 122 in the microwave radiation plane that determines the radiation characteristic of the slot 122 is, for example, as shown in Fig. Specifically, the four slots 122 are formed uniformly so that the overall shape is a circular shape. These slots 122 are all formed in the same shape and elongated along the circumference. These slots 122 are arranged symmetrically with respect to the center O of the microwave radiation plane of the antenna main body 121. [

The length of the slot 122 in the circumferential direction is (? G / 2) -δ, and is designed so that the peak of the microwave electric field strength comes to the center position of the slot 122. Here,? G is the effective wavelength of the microwave, and? Is a fine adjustment component (including 0) for finely adjusting the uniformity of the electric field intensity in the circumferential direction (angle direction). g,

_{^{λg = λ / ε s 1/}} 2

. Where? S is the permittivity of the slot and? Is the wavelength of the microwave in vacuum. The length of the slot 122 is not limited to about lambda g / 2, but may be obtained by subtracting the fine adjustment component (including 0) from an integral multiple of lambda g / 2.

Adjacent ones of the slots 122 are configured so that the end of one slot 122 and the end of the other slot 122 are overlapped with each other at a predetermined distance in the radial direction. As a result, there is no portion in which there is no slot in the circumferential direction, and the radiation characteristic in the circumferential direction is designed to be uniform. The slot 122 is divided into three portions along the circumferential direction, that is, a center portion 122a, a left end portion 122b and a right end portion 122c, and the left end portion 122b and the right end portion 122c are substantially fan- Respectively, which are arranged on the outer circumferential side and the inner circumferential side, respectively, and the central portion 122a has a linear shape connecting them. The right end portion of the slot adjacent to the left end portion 122b is disposed such that the left end portion 122b is upward and the left end portion of the slot adjacent to the right end portion 122c is positioned so that the right end portion 122c is downward . The center portion 122a, the left end portion 122b, and the right end portion 122c have substantially equal lengths. That is, the central portion (122a) is (λg / 6) -δ _1, the left end portion (122b) and right end (122c) on both sides, respectively (λg / 6) -δ _2, and (λg / 6) -δ ₃ Length. However, δ ₁ , δ ₂ , and δ ₃ are fine adjustment components (including 0) for finely adjusting the uniformity of the electric field intensity in the circumferential direction (angle direction). It is preferable that the length of the portion where the adjacent slots overlap is equal, and therefore, it is preferable that? ₂ =? ₃ .

The slot 122 is formed such that its inner periphery is located at a position of (? G / 4) +? 'From the center of the microwave radiation plane of the antenna main body 121. However, δ 'is a fine adjustment component (including 0) for finely adjusting the electric field intensity distribution in the radial direction. The length from the center to the inner circumference of the slot is not limited to about? G / 4, but may be obtained by adding a fine adjustment component (including 0) to an integral multiple of? G / 4.

By arranging the end portions of the slots with low electric field strength in such a manner as to overlap each other, the electric field strength of the antenna 45 can be increased, and as a result, the electric field intensity distribution in the peripheral direction (angular direction) can be made uniform.

Further, the number of slots is not limited to four, and for example, five or more slots can achieve the same effect. The slot shape is not limited to that shown in Fig. 8. For example, slots of a plurality of arcuate shapes may be formed uniformly on the circumference, or the like.

The distance between the overlapping portions of the left end portion 122b and the right end portion 122c in the upper portion 122A of the slot 122 is wider than the interval in the lower portion 122B, As shown in Fig. By increasing the distance between the overlapping portions of the left end portion 122b and the right end portion 122c in the upper portion 122A as described above, the conductance of the gas in the gas diffusion space 123 is increased to increase the uniformity of the gas flow rate .

The dielectric layer 126 is made of a dielectric material such as quartz and is provided to make the surface of the antenna 45 a floating potential with respect to the plasma. That is, the surface of the metal (conductor) of the antenna main body 121 is directly insulated from the plasma by the dielectric layer 126. From the viewpoint of preventing the abnormal discharge, the entirety of the antenna 45 may be set to the floating potential without being grounded. For example, by insulating the outer conductor 52 and the antenna 45 and between the ceiling plate 85 and the antenna 45, the antenna 45 can be isolated from the grounded outer conductor 52 and the chamber 1, Thereby making the whole floating potential.

The dielectric layer 126 is formed to have a thickness of? / 7 so that a surface acoustic wave is formed on the surface of the antenna 45 (? Is the wavelength of the microwave in a vacuum). The dielectric layer 126 may be a film formed by a film forming technique such as spraying, or may be a plate.

The direct current voltage may be applied to the antenna 45. Thus, when the microwave power is applied, the thickness of the sheath that propagates through the surface acoustic wave formed on the surface of the antenna 45 can be controlled. Thus, the electron density distribution, ion density distribution, and radical density distribution of the plasma can be optimized.

In the present embodiment, the main amplifier 48, the tuner 60, and the antenna 45 are disposed close to each other. The tuner 60 and the antenna 45 constitute a lumped constant circuit existing within a half wavelength and the combined resistance of the antenna 45 and the waveguide material 82 is set to 50? 60 are tuned directly to the plasma load, and energy can be efficiently transferred to the plasma.

Each component in the plasma processing apparatus 100 is controlled by a control unit 140 having a microprocessor. The control unit 140 includes a storage unit for storing a process recipe of the plasma processing apparatus 100 and a process recipe as a control parameter, input means and a display, and controls the plasma processing apparatus in accordance with the selected process recipe.

≪ Operation of Plasma Processing Apparatus &

Next, the operation of the plasma processing apparatus 100 configured as described above will be described.

First, the wafer W is carried into the chamber 1 and loaded on the susceptor 11. A plasma generating gas such as Ar gas is introduced into the gas diffusion space 123 of the antenna 45 from the gas supply source 110 through the gas piping 111 and discharged from the gas discharge holes 125, The microwave transmitted from the microwave output section 30 of the microwave plasma source 2 through the amplifier section 42 and the microwave radiating section 43 of each antenna module 41 of the microwave supplying section 40 is passed through the antenna 45, Is radiated into the chamber 1 from the slot 122 of the antenna 45, and a surface acoustic wave is formed on the surface of the antenna 45 to generate a surface acoustic wave plasma. The processing gas introduced from the gas supply source 110 into the gas diffusion space 123 through the gas piping 111 is discharged from the gas discharge hole 125 into the chamber 1 and excited by the surface wave plasma And the plasma W of the processing gas is subjected to a plasma treatment, for example, an etching treatment.

In the microwave plasma source 2, the microwave power oscillated from the microwave oscillator 32 of the microwave output unit 30 is amplified by the amplifier 33 and then supplied to the distributor 34 And the divided microwave power is led to the microwave supply part 40. [ In the microwave supply unit 40, the microwave power distributed in this manner is individually amplified by the main amplifier 48 constituting the solid state amplifier, and is supplied to the microwave transmission path 44 of the microwave radiating unit 43 Transmitted through the microwave transmission path 44, transmitted through the trench material 82, and radiated through the slot 122 of the antenna 45. Then, a metal surface wave is formed in the outer skin formed on the surface of the antenna 45, and the surface wave plasma is generated in the space in the chamber 1 by this surface wave.

In this embodiment, since the microwave plasma gas is also introduced into the chamber 1 from the antenna 45 provided in the ceiling plate 85, the controllability of gas flow can be improved, and the radiation direction of the microwave and the gas flow direction So that the gas can be efficiently plasmatized.

Since the antenna 45 is made of metal (conductor), the microwave is not transmitted, and when the gas passes through the gas diffusion chamber 123 and the gas discharge hole 125, There is no problem such as discharge. Further, if a shower structure is formed on a relatively thick dielectric member (microwave transmission window) provided at the tip end side of the antenna 45 in the past, there is a problem in that it is difficult to work in addition to a problem such as an abnormal discharge. Similarly, the gas discharge hole 125 can be relatively easily formed in the metal antenna 45.

However, when the surface wave plasma is formed on the surface of the microwave radiation antenna made of metal, it has been found that the plasma concentrates in the vicinity of the slot 122 to emit (generate) and the uniformity in the diameter direction is disturbed.

As a result of investigating this cause, it has been found that the thickness of the jacket is different from that of the slot portion and the slot portion. This is shown in FIG. As shown in (a), the potential difference with the plasma becomes large, and the thickness of the shell becomes a thickness (proportional to 1/2 of the magnetic bias voltage Vdc) in accordance with the plasma state do. On the other hand, the portion other than the slot portion is made of metal and is grounded, so that the potential difference with the plasma becomes small as shown in (b), and the shell becomes thin. In the area where the outer skin is thinned as described above, reflection and attenuation of the microwave occur, and the surface wave is cut off. As a result, the surface wave plasma is not sufficiently generated at that portion and the light emission is weak. That is, the surface wave plasma does not spread sufficiently at portions other than the slot portions.

Therefore, in this embodiment, the dielectric layer 126 is provided on the surface of the antenna 45, which is a microwave radiation antenna, so that the portion other than the slot portion also becomes the floating potential with respect to the plasma. That is, the dielectric layer 126 directly insulates the plasma from the surface of the metal (conductor) of the antenna main body 121 to make the floating potential not only the slot portion but also the slot portion. As a result, as shown in Fig. 10, the outer surface of the portion of the antenna 45 other than the slot portion on the surface of (b) becomes thicker and becomes the same as the outer skin thickness of the slot portion of (a) The surface wave plasma is sufficiently generated. As a result, the surface wave plasma spreads to portions other than the slot portion, and a uniform surface wave plasma can be generated in the radial direction. Further, since the dielectric layer 126 may be thin, processing of gas discharge holes and slots is easy.

As described above, according to the present embodiment, at least a part of the metal surface of the antenna main body is constructed so as to be DC insulated from the surface wave plasma, the outer surface of the insulated portion can be made thick, It is possible to generate a surface wave plasma having a uniform surface on the surface by sufficiently spreading the plasma.

The dielectric layer 126 is not necessarily formed on the entire surface of the antenna main body 121, but may be formed at least in part.

Practically, a plasma generation experiment was conducted in the case where the dielectric layer 126 was not formed and in the case where the dielectric layer 126 was formed. Here, the dielectric layer 126 was formed as a film, and Ar gas was used as the plasma generation gas. Plasma was produced under the conditions of a pressure of 0.5 Torr, a microwave power of 400 W, a pressure of 1 Torr, and a microwave power of 100 W and 125 W.

The results are shown in Figs. 11 to 13. Fig. 11 shows the emission state of the plasma. In the case where the dielectric layer 126 is not formed, as shown in Fig. 11 (a), when the dielectric layer 126 is formed , It can be seen that the surface wave plasma is sufficiently spread as shown in (b). 12 is a view showing the distribution of the electron density by taking the distance in the radial direction on the axis of abscissa and taking the electron density on the axis of ordinate and Fig. 13 is a graph showing the distribution of the electron density normalized by the position electron density of 0 in the radial direction in Fig. And shows the distribution of the density. From this figure, it can be seen that by providing the dielectric layer 126, a surface wave plasma spreads and a more uniform electron density distribution can be obtained.

However, it is not always easy to form a dielectric such as quartz in a metal by spraying or the like. On the other hand, it is relatively easy to use a dielectric thin plate as the dielectric layer 126. [ Therefore, it is preferable in terms of production to use a dielectric thin plate as the dielectric layer 126. [

However, when a thin dielectric plate is used as the dielectric layer 126, it is evident that a slight gap (about 0.3 to 0.5 mm) is inevitably generated between the antenna main body 121 and the dielectric thin plate and an abnormal discharge occurs in the gap . If an abnormal discharge is generated, the power transmission efficiency to the plasma remarkably decreases, which is not preferable.

In order to clarify the cause of such an abnormal discharge, electromagnetic field simulation analysis at the time of installing a thin dielectric plate was carried out. As a result, when such a thin dielectric plate is used as the dielectric layer 126, it is possible to prevent the TE of the dielectric main body 121 and the dielectric thin plate 126 from being generated in the gap 130 between the antenna main body 121 and the dielectric thin plate 126, ₁₀ waves are propagated, and as shown in Fig. 15, the electric field becomes strong particularly in the inner region of the plurality of slots 122, and anomalous discharge tends to occur easily.

In order to attenuate such TE ₁₀ wave, it is conceivable to coat a metal film on the surface of the dielectric thin plate facing the antenna main body 121.

16, when the metal film is coated on the entire surface except for the slot 122 of the dielectric thin plate and the gas discharge hole 125, according to simulation of the electromagnetic field simulation, The electric field of the gap of the thin plate 126 becomes rather high. This is considered to be because the influence of the reflection of the microwave increases when the metal film is coated on the entire surface.

Therefore, when a dielectric thin plate is used as the dielectric layer 126, a metal film is coated on a part of the surface of the dielectric thin plate 126 which faces the antenna main body 121.

Next, a pattern for coating a metal film was examined.

As shown in Fig. 17, when a metal film is coated on the central portion of the dielectric thin plate 126 (the inner side of the slot 122), electromagnetic field simulation analysis is performed. As a result, as shown in Fig. 18, It was confirmed that the electric field of the gap between the dielectric thin plate 121 and the dielectric thin plate 126 was lowered. 17, since the metal film exists up to the position near the outer diameter of the upper portion 122A which is larger than the outer diameter of the lower portion 122B, which is the microwave radiation portion of the slot 122, the electric field of the slot portion becomes higher, Abnormal discharge may occur.

Therefore, as shown in FIG. 19, when a pattern of the metal film coating is optimized by being adjusted to the outer diameter of the lower portion 122B, which is the microwave radiation portion of the slot 122, 20, the electric field of the slot portion is relaxed, and the possibility of abnormal discharge is lowered.

21, the metal film 131 is coated on a part of the surface of the dielectric thin plate 126 facing the antenna main body 121, preferably the range from the center to the outer diameter of the slot 122 . Thus, abnormal discharge of the gap 130 between the antenna main body 121 and the dielectric thin plate 126 can be suppressed.

At this time, the method of forming the metal film 131 is not particularly limited as long as it is a film forming technique, but it is preferable to use thermal spraying. The thickness of the metal film 131 is preferably 5 to 150 mu m.

<Other applications>

The present invention is not limited to the above-described embodiments, but may be modified in various ways within the scope of the spirit of the present invention. For example, the configuration of the microwave output section 30 and the microwave supply section 40 is not limited to the above-described embodiment. For example, the directivity control of the microwave radiated from the antenna may be performed, In this case, the phase shifter is unnecessary. Further, in the microwave radiating section 43, the trench material 82 is not essential.

In the above-described embodiment, a plurality of microwave radiating units are provided, and a plurality of microwave radiating antennas are provided in conjunction with the plurality of microwave radiating units. However, one microwave radiating unit and one microwave radiating antenna may be provided.

In the above embodiment, the etching treatment apparatus is exemplified as the plasma treatment apparatus. However, the present invention is not limited to this, and it can be used for other plasma treatment such as an oxynitriding treatment including ashing treatment, oxidation treatment and nitriding treatment and ashing treatment . The substrate to be processed is not limited to the semiconductor wafer W but may be another substrate such as an FPD (flat panel display) substrate typified by a substrate for an LCD (liquid crystal display), a ceramics substrate, or the like.

1: chamber
2: Microwave plasma source
11: susceptor
12: Support member
15: Exhaust pipe
16: Exhaust system
17: Incoming exit
30: Microwave output section
31: microwave power source
32: microwave oscillator
40: microwave supply part
41: Antenna module
42:
43: microwave radiation part
44: Waveguide
45: microwave radiation antenna
52: outer conductor
53: inner conductor
54: power supply mechanism
55: microwave power introduction port
60: tuner
82: tributary material
85: Ceiling board
100: Plasma processing device
110: gas supply source
111: Gas piping
121: Antenna body
122: Slot
123: gas diffusion space
125: gas discharge hole
126: Dielectric layer (dielectric thin plate)
130: Clearance
131: metal film
140:
W: Semiconductor wafer

Claims (12)

A plasma processing apparatus for forming a surface wave plasma in a chamber and performing plasma processing, the plasma processing apparatus comprising: a microwave radiation antenna which is output from a microwave output unit and radiates a microwave transmitted through a microwave transmission path into a chamber;
An antenna main body made of a conductor,
A plurality of slots provided in the antenna main body for radiating microwaves,
And a plurality of gas discharge holes provided in the antenna main body for discharging a process gas into the chamber,
A metal surface wave is formed on the surface by the microwave, a surface wave plasma is generated by the metal surface wave,
Wherein at least a part of the metal surface of the antenna body is DC-insulated from the surface acoustic wave plasma,
At least a part of the surface of the antenna main body is insulated by covering it with a dielectric layer having a thickness that can sustain a surface acoustic wave,
Wherein the dielectric layer is formed of a thin dielectric sheet,
Wherein the dielectric thin plate has a metal film having a pattern except for the slot and the gas discharge hole on a part of the surface facing the antenna main body. delete The microwave radiating antenna according to claim 1, wherein the thickness of the dielectric layer is not more than? / 7 when the wavelength of the microwave in vacuum is?. The microwave radiation antenna according to claim 1, wherein the dielectric layer is a film formed by a film formation technique. delete delete The antenna according to claim 1, wherein the plurality of slots are arranged on a surface of the antenna main body in a columnar shape, and the metal film is provided in a range from a center of the thin dielectric plate to a position corresponding to an outer diameter of the slot , Microwave radiation antenna. The microwave radiating antenna according to claim 1, wherein the antenna body is DC insulated from the chamber. A microwave plasma source for radiating a microwave into a chamber of a plasma processing apparatus to form a surface wave plasma,
A microwave output unit for generating and outputting a microwave,
And a microwave supply unit for supplying the microwave outputted from the microwave output unit into the chamber,
The microwave supply unit,
A transmission line for transmitting microwaves output from the microwave output unit;
And a microwave radiation antenna for radiating a microwave into the chamber,
The microwave radiation antenna includes:
An antenna main body made of a conductor,
A plurality of slots provided in the antenna main body for radiating microwaves,
And a plurality of gas discharge holes provided in the antenna main body for discharging a process gas into the chamber,
Wherein a surface acoustic wave is generated by the microwave and a surface acoustic wave is generated by the surface acoustic wave so that at least a part of the metal surface of the antenna body is insulated from the surface acoustic wave plasma,
At least a part of the surface of the antenna main body is insulated by covering it with a dielectric layer having a thickness that can sustain a surface acoustic wave,
Wherein the dielectric layer is formed of a thin dielectric sheet,
Wherein the dielectric thin plate has a metal film having a pattern except for the slot and the gas discharge hole on a part of the surface facing the antenna main body. The microwave plasma source according to claim 9, wherein the microwave supply unit has a plurality of microwave radiation antennas. A chamber for accommodating a substrate to be processed;
A gas supply mechanism for supplying a process gas,
And a microwave plasma source for radiating a microwave into the chamber to form a surface wave plasma,
In the microwave plasma source,
A microwave output unit for generating and outputting a microwave,
And a microwave supply unit for supplying the microwave outputted from the microwave output unit into the chamber,
The microwave supply unit,
A transmission line for transmitting microwaves output from the microwave output unit;
And a microwave radiation antenna for radiating a microwave into the chamber,
The microwave radiation antenna includes:
An antenna main body made of a conductor,
A plurality of slots provided in the antenna main body for radiating microwaves,
And a plurality of gas discharge holes provided in the antenna main body for discharging a process gas into the chamber,
Wherein a surface acoustic wave is generated by the microwave and a surface acoustic wave is generated by the surface acoustic wave so that at least a part of the metal surface of the antenna body is insulated from the surface acoustic wave plasma,
At least a part of the surface of the antenna main body is insulated by covering it with a dielectric layer having a thickness that can sustain a surface acoustic wave,
Wherein the dielectric layer is formed of a thin dielectric sheet,
Wherein the dielectric thin plate has a metal film having a pattern except for the slot and the gas discharge hole on a part of a surface facing the antenna main body,
A surface acoustic wave plasma generated by the gas supplied from the gas supply mechanism is generated by the surface acoustic wave formed on the surface of the microwave radiation antenna by the microwave supplied into the chamber from the microwave plasma source, Wherein the plasma processing is performed by the plasma. 12. The plasma processing apparatus according to claim 11, wherein the microwave supply unit has a plurality of microwave radiation antennas.

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