JP2003168681A - Microwave plasma treatment device and treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave plasma treatment device and treatment method in which plasma treatment can be carried out with high reliability and stability using an antenna means which is strong mechanically or against thermal deformation even when high power microwave is radiated. <P>SOLUTION: The microwave plasma treatment device comprises an antenna means having slots provided on the microwave introduction face side of a dielectric window for transmitting a microwave. The antenna means is not inserted with a dielectric plate for shortening the wavelength in the tube and an atmospheric condition is present internally. A plurality of pairs of slots having different directions are arranged circularly only one round on a microwave radiation plate having a thickness of 0.5 mm-3.0 mm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave-excited plasma processing apparatus (hereinafter referred to as a microwave plasma processing apparatus) and a plasma processing method using this apparatus, and particularly 0.5 W / cm ² to 20 W / A plasma device having a microwave radiating antenna for introducing microwaves up to a high power density of cm ² , wherein film formation, etching, and film composition improvement on a substrate that is an object to be processed in semiconductor LSI fabrication. The present invention relates to a plasma processing apparatus capable of performing reforming and ashing, and a plasma processing method using this apparatus.

[0002]

2. Description of the Related Art In recent years, single-wafer processing has become the mainstream for fine processing of wafers due to miniaturization of devices in semiconductor LSIs and increase in diameter of wafers. In the plasma process of CVD or etching among them, a plasma source of DC or high frequency excitation is used. Further, ECR (electron cyclotron resonance) is used in a plasma source using microwaves. As described above, in the case of plasma excited by high frequency or ECR, it is difficult to generate a uniform plasma with a large diameter, in addition to applying a magnetic field in order to generate high density plasma. Further, there is a problem that the plasma potential is as high as about 20 eV and the chamber wall is sputtered to cause metal contamination, and further the ion irradiation energy for the floating substrate is as high as 10 eV or more, which causes damage to the substrate. It was

Therefore, by using an antenna means such as a radial line slot antenna (hereinafter referred to as "RLSA"), microwaves are introduced into the vacuum atmosphere from the slots through the dielectric material to create a strong microwave electric field. A method of generating high-density surface wave plasma with low electron temperature and low plasma potential has been developed.
For example, in the device described in Japanese Patent No. 3136054, a dielectric is inserted inside the antenna, and a circularly polarized microwave is radiated from a pattern in which a number of slots are concentrically or spirally arranged according to a certain rule. It is said that plasma can be efficiently generated without using a magnetic field.

On the other hand, Japanese Patent No. 2928577 describes an apparatus in which a microwave transparent dielectric window is not installed on the chamber wall, and vacuum sealing is performed between the dielectric inside the antenna and the waveguide of the antenna. Has been done. The slot has "a plurality of thin wire-shaped slits which are oriented in different directions and are arranged concentrically or spirally", and the dielectric wavelength inside the antenna shortens the guide wavelength λg inside the antenna.
Further, by using a magnetic field, it is assumed that plasma is generated by the synergistic effect of the microwave and the magnetic field, and the operating pressure is 10 ⁻³ T.
It is set to a very low pressure of orr level (~ 10 ^-1 Pa level).

[0005]

However, by inserting a dielectric into the antenna to shorten the guide wavelength λg and forming as many slots as possible in the microwave radiation plate, a uniform and efficient in-plane is achieved. When the above-mentioned conventional antenna for the purpose of radiating microwave is used, there is a problem that the microwave radiating plate is deformed with time due to heat generation and heat from the substrate side, and the plasma becomes unstable.
Also, if the microwave radiation plate is deformed and a gap is created between the microwave radiation plate and the dielectric inside the antenna, abnormal discharge may occur due to electric field concentration, and sometimes the dielectric may be damaged. there were.

This is because the guide wavelength λg is shortened by inserting a dielectric inside the antenna. Therefore, in order to prevent the radiation characteristic from being deteriorated, the thickness of the microwave radiation plate is 0.3 m.
This is because the thickness must be extremely thin, such as about m, and the mechanical strength and the heat conduction in the radial direction are extremely deteriorated by that amount.
To solve these problems, an antenna in which a thin film is directly formed on a metal conductor having a slot for functioning as an antenna by a method such as vapor deposition or plating using a dielectric such as ceramics has been proposed. However, there is a problem that the film peels off due to the difference in expansion coefficient between the materials due to heat, and there is a problem in adhesion. Furthermore, it was difficult to use for general purposes in terms of manufacturing cost and delivery time.

It is also conceivable to bond or press the microwave radiating plate to the dielectric inside the antenna and the microwave transmitting window on the vacuum container side to suppress the deformation, but the problem of heat removal complicates the device. There is a problem that it will end up. As described above, the problem of why a thin microwave radiation plate (that is, a slot having a small thickness) must be used when the guide wavelength λg is short is determined by the penetration length and the transmission power of the microwave slot. It can be understood by calculating. This point will be described below.

First, the electric power P passing through the slot can be expressed by the following equation (1). (Equation 1) P = P ₀ exp (−t ² / δ) (1) where P _{0 is the} input power, t is the thickness of the slot, and δ is the penetration length. As is clear from the equation (1), the power P that can be transmitted through the slot exponentially decreases in proportion to the square of the slot thickness. The penetration length δ is given by the following equation (2). (Formula 2) Here, a is the length of the long side of the slot, and λg is the guide wavelength of the microwave.

Further, in the equation (2), when the length a of the long side of the slot is λg / 2 or more, the sign in the route becomes zero or minus. This means that when the length of the long side of the slot is longer than half the guide wavelength, the microwave transmits power like a waveguide no matter how thick the slot is in the traveling direction of the microwave. It means that you can do it. However, in an antenna that radiates microwaves on a plane like this time, in order to control the normal power to be emitted on a plane, many slots less than 1/2 of the guide wavelength are cut upstream in the microwave propagation direction. ing. It should be noted that the slot on the most downstream side, which is cut into concentric circles, may be made to radiate all the power, so this is not a limitation.

From the above equations (1) and (2), for example, when the guide wavelength λg is 100 mm and 40 mm, the length a of the long side of the slot is a = (λg / 2-0.
5) Actually find the penetration length when it is set to mm. When alumina is used as the dielectric, λg is about 1 with respect to the free space wavelength (122 mm@2.45 GHz).
Since / √ε, the actual value is about λg = 40 mm. Therefore, the following calculation was performed with λg = 40 mm. When λg = 100 mm, a = 49.5 and δ = 111.8 mm. When λg = 40 mm, a = 19.5 and δ = 27.9 mm.

By substituting these values into the equation (1), the difference in the power transmission rate when the slot thickness t is changed is shown in Table 1.
Put together. (Table 1)

As can be seen from the results in Table 1, the shorter the guide wavelength λg (when a dielectric is used), the closer the long side of the slot is to λg / 2.
When microwaves pass through the slot, they are greatly affected by the thickness thereof, and the thicker the slot is, the more the transmitted power is extremely reduced. Further, when the value of the length a of the long side of the slot is further shortened and the penetration length is also shortened, the influence of the thickness is further exerted. In addition, if there is a dielectric inside the antenna, the dielectric is not strictly filled in the thickness direction of the slot, so the microwave has an extremely long wavelength immediately after being radiated from the slot. In reality, it is predicted that the effect of thickness will be more significant.

The above is the guide wavelength λg in the prior art.
That is the reason why a thin slot plate must be used when is short. An object of the present invention is to solve the above-mentioned problems of the prior art. Even when performing high-power microwave radiation from the antenna means, by using the antenna means that is also strong in thermal deformation and mechanical strength, It is an object of the present invention to provide a microwave plasma processing apparatus capable of performing highly reliable and stable plasma processing and a processing method using this apparatus.

[0014]

A microwave-excited plasma processing apparatus of the present invention supplies an exhaust means for depressurizing the inside of a microwave plasma processing container and a gas for exciting plasma in the processing container. Gas supply means for
An antenna having a microwave window for transmitting microwaves provided on the wall surface of the processing container and an antenna means provided on the microwave introducing surface side of the dielectric window, the antenna having a microwave radiation plate with slots formed therein. Means and a microwave generation means provided on the upstream side of the antenna means, and a microwave plasma processing apparatus is configured so that a substrate is installed in the processing container so as to face the dielectric window. In the inside of the antenna means, there is no dielectric plate inserted for shortening the wavelength in the tube and it is in an atmospheric state, and the microwave radiating plate of the antenna means has a pair of slots with different directions. Consists of a plurality of sets arranged in a circle only once. A plurality of such slot pairs are arranged adjacent to each other in a circular shape.

The microwave radiation plate of the antenna means is
It has a thickness of 0.5 mm or more and 3.0 mm or less. If it is less than 0.5 mm, it is likely to be thermally deformed and the mechanical strength is low. Further, if it exceeds 3.0 mm, the microwave radiation characteristics deteriorate. In the microwave plasma processing apparatus of the present invention, in order to efficiently remove heat from the microwave radiating plate, a water channel is cut in the inner shaft of the coaxial tube or the antenna body to enable water cooling. It is preferable that the plate thickness is about 1.0 mm. As the thickness of the microwave radiation plate increases, the removal of heat is promoted and the strength also increases, so that distortion due to heat is less likely to occur, but the microwave radiation characteristics deteriorate. The optimum thickness for both of these problems is 1.0
It will be about mm. Of course, this optimum thickness varies depending on the microwave input power (power density) and the wavelength inside the antenna.

The length of the slot formed in the microwave radiation plate is about 1/2 of the guide wavelength in the antenna, and its width is generally about 2 mm to 8 mm, preferably about 4 mm to 8 mm. Is. If it is less than 2 mm, there is a problem that the radiation intensity decreases due to the small opening, and if it exceeds 8 mm, the influence of the electric field in the width direction may disturb the electromagnetic field of the radiated microwave. A test was conducted using a microwave radiation plate having slots of 2 mm, 4 mm, and 6 mm width, and the result was that the one having a width of 6 mm was most stable.

According to the present invention, the dielectric window for microwave transmission has a ring-shaped sleeve on the outer periphery of the surface on the processing container side so that the plasma excitation region does not directly contact the metal surface of the processing container wall. It is preferable to have. Further, the surface shape and thickness of the central portion of the microwave transparent dielectric window are adjusted in-plane so that the area of the dielectric window corresponding to a predetermined area of the substrate has a thickness different from other areas. It may be configured as follows. The dielectric window is also provided with a convex portion in a region of the dielectric window corresponding to a predetermined region of the substrate on one of the surface of the processing container side and the surface of the microwave introduction side, so that the predetermined region of the substrate is provided. Is configured such that the thickness of the area of the dielectric window corresponding to the above is thicker than the thickness of other areas, or the area corresponding to the convex portion on the surface opposite to the surface on which the convex portion is provided. I also have a recess
The thickness of the region where the convex portion and the concave portion are provided may be the same as the thickness of the other regions.

Further, the dielectric window is provided with concentric steps on its processing container side surface so that the distance from the surface of the substrate to the surface of the dielectric window varies depending on the region of the substrate, and the density of plasma generated. May be configured to be uniform on the substrate. This concentric step is
The dielectric window may be discontinuously provided with a diameter that is an integral multiple of 1/2 wavelength in the radial direction. Further, the dielectric window has a central region having a different thickness from other regions, a region having a convex portion, and a region having concentric steps, and the thickness of these regions is It may be about 1/4 of the wavelength of the microwave.

According to the present invention, considering the thermal strength and mechanical strength of the microwave radiation plate as described above, the microwave radiation plate has a thickness of 0.
A thick conductor having a thickness of 5 to 3.0 mm, preferably 1 mm is used, and the microwave is guided from the microwave oscillator to the microwave transparent dielectric window so that the microwave can be efficiently radiated even if a thick radiation plate is used. The dielectric means is not inserted in the waveguide, the inside of the waveguide is kept in the atmospheric state, and the antenna means devised so as to make the wavelength inside the antenna longer than before. By performing the plasma processing using such an antenna means, the instability of the plasma due to the distortion of the microwave radiation plate is eliminated, and a highly stable process can be performed. In addition, the structure is simplified and expensive Teflon (registered trademark) for supporting the inner shaft of the coaxial tube and expensive ceramic plate
It is not necessary to use a ceramic insulator or the like. Therefore, the plasma processing apparatus of the present invention can be manufactured in a short period with a simple structure.

The microwave plasma processing method of the present invention comprises:
The above-described processing device, that is, microwave radiation in which there is no dielectric plate inside and the antenna means is in an atmospheric state, and a plurality of pairs of slots having different directions are arranged in a circle for only one round. It is performed using a microwave plasma processing apparatus equipped with an antenna means having a plate. At this time, the gas pressure in the processing container is 0.1 Pa to 100.
The frequency of the microwave applied to the electrode is preferably 2 GHz to 10 GHz. If the gas pressure is less than 0.1 Pa, and if it exceeds 1000 Pa, it becomes difficult to start and maintain the discharge. In addition, the frequency is 2GH
If it is less than z, the desired plasma density cannot be obtained, and 10G
If the frequency exceeds Hz, the equipment for power amplification becomes large and the handling thereof is difficult.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A microwave plasma processing apparatus according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows, as an example of an embodiment of the present invention, in a plasma processing apparatus for a semiconductor substrate using microwaves, an antenna body has a hollow inside as an antenna means for introducing microwaves, and a microwave radiating plate is used. A plurality of pairs of rectangular slot pairs in different directions are arranged in a circle (annular shape) in only one round, and the radiation plate has a predetermined thickness (for example, 1.0 mm). It is sectional drawing which shows a structure. FIG. 2 shows an example of a slot pattern formed in the microwave radiation plate.
4 to 6 show a microwave plasma processing apparatus according to another embodiment of the present invention.

In FIG. 1, 101 is a processing container for performing plasma processing, 102 is a coaxial waveguide converter and antenna means, 103 is a pair of rectangular slots 1 in different directions.
03a (b) (slot pair 103a, 103 shown in FIG. 2)
b) a microwave radiating plate in which a plurality of sets are arranged in a ring only for one round, 104 is a microwave window for transmitting microwaves, 105 is plasma formed by a microwave electric field above the substrate for etching or film formation, Reference numeral 106 is a magnetron for oscillating microwaves, 107 is an isolator, 108 is a tuner, 109 is a waveguide, 110 is a plasma forming gas supply means, 111 is an exhaust pump, and 112 is the container 1.
A pressure adjusting valve for adjusting the pressure in 01, 113 a substrate to be plasma-processed, 114 an electrode for holding the substrate, 11
Reference numeral 5 is a high frequency power source for applying a high frequency to the substrate electrode 114 and the substrate 113 as necessary, and 116 is a matching device for adjusting the high frequency impedance. Waveguide 1
In the microwave waveguide from 09 to the microwave radiating plate 103, no dielectric is inserted, and
The microwave waveguides up to the dielectric window 104 are all in the atmospheric state. In addition, the microwave radiation plate 10
3 has a predetermined thickness (for example, 1 mm). At the outer peripheral portion of the dielectric window 104, that is, the portion away from the central portion, a ring-shaped sleeve 11 is formed so that the plasma excitation region does not directly contact the metal surface of the processing container wall.
7 are formed.

The outline of the plasma processing method performed by using the apparatus shown in FIGS. 1 and 2 will be described below. In the apparatus of this embodiment, the gas for exciting the plasma 105 by the gas supply means 110 is supplied to the processing container 10.
1, the raw material and the reaction by-product gas are exhausted by the exhaust pump system 111, the pressure inside the container 101 is reduced, and the process pressure inside the container 101 is adjusted by the pressure adjusting valve 112. Microwave power supply (magnetron) 10
The microwave oscillated and amplified in 6 is transmitted to the tuner 108.
The rectangular slots 103a, 103 introduced into the antenna means 102 through the microwave radiation plate 103
Radiated from b. At this time, the reflected wave is the tuner 10
The reflected wave, which is returned to the container 101 side by 8, is absorbed by the isolator 107 and is prevented from returning to the magnetron 106. Microwaves radiated from the microwave radiating plate 103 through the slots 103a and 103b are introduced into the container 101 in a vacuum atmosphere through the dielectric window 104, and the electromagnetic field generated by the microwaves causes the inside of the container 101 to be closed. A plasma 105 is formed on the surface.

When the density of the formed plasma 105 exceeds the cutoff density of microwaves in the vicinity of the dielectric window 104, the penetration length of microwaves becomes several millimeters, and a part of the microwaves within a range of several millimeters in the plasma. Energy is plasma 10
5 is absorbed and the rest is reflected. Generated plasma 1
Depending on the slot pattern, the density distribution of No. 05 can be adjusted evenly on a flat surface.
It also largely depends on the pressure inside the chamber 1 and the shape of the dielectric window 104. The plasma 105 thus generated reaches the substrate 113 by diffusion, and the substrate 113 can be subjected to a desired plasma treatment.

Next, a plasma processing apparatus according to another embodiment of the present invention will be described. In the plasma processing apparatus which is another example of the embodiment of the present invention shown in FIG.
As a dielectric window 404 that constitutes a microwave introduction window,
A convex portion (diameter: D4) is provided on the surface of the atmosphere side (microwave introduction side) in a concentric region, that is, a region from the center of the circular dielectric window to a predetermined equal distance, and the thickness of the portion is set. It uses a different dielectric window. The pattern of the slot pair has the same configuration as that shown in FIG. 2, and the other configurations are the same as those shown in FIG. 1, and the reference numerals in FIG. 4 are the same as those in FIG. 1 unless otherwise specified. Reference numerals indicate the same configurations.

A dielectric window 404 which is a microwave introduction window
Can be made of the following materials similar to the dielectric window 104 shown in FIG. When a quartz plate having a thickness of 50 mm is used, for example, the atmosphere side of the dielectric window 404 has a convex shape in the region (D4) up to φ = 95 mm, and the thickness of the convex portion is 60 mm. For example, the diameter (D
w) The thickness of the dielectric window directly above the 200 mm silicon substrate is 60 mm in the region immediately above it in the region where the radius of the substrate is 0 mm to 47.5 mm (D4x1 / 2). In other areas, the thickness becomes 50 mm.

In the plasma processing apparatus shown in FIG. 5 which is another example of the embodiment of the present invention, a dielectric window 504 constituting a microwave introduction window is formed from a concentric region, that is, from the center of the dielectric window. Contrary to the case of FIG. 4, a convex portion (diameter: D
5) is provided, and the dielectric window in which the thickness of the portion is changed is used. The pattern of slot pairs has the same configuration as that shown in FIG. 2, and the other configurations are the same as those shown in FIG. 1, and the reference numerals in FIG. 5 are the same as those in FIG. 1 unless otherwise noted. Reference numerals indicate the same configurations.

A dielectric window 504 which is a microwave introduction window.
Can be made of the following materials similar to the dielectric window 104 shown in FIG. When a quartz plate having a thickness of 44 mm is used, for example, the vacuum side of the dielectric window 504 is made convex in the region (D5) up to φ = 60 mm, and the thickness of the convex part is made 60 mm. For example, the diameter (D
w) The thickness of the dielectric window directly above the 200 mm silicon substrate is 60 mm in the region located immediately above it in the region (D5x1 / 2) where the radius of the substrate is from 0 mm to 30 mm, The thickness in the other regions is 44 mm. In addition, the radius of the substrate is 0 mm to 30
The distance (L52) from the substrate to the dielectric plate is 40 mm in the area up to mm (D5 × 1/2), and the distance (L51) is 56 mm in the other areas.

In the plasma processing apparatus shown in FIG. 6 which is still another example of the embodiment of the present invention, the dielectric window 604 forming the microwave introduction window has a concentric region, that is, the center of the dielectric window. To a predetermined equidistant area, the surface of the microwave introduction side is convex, and the surface of the vacuum side is concave so that the dielectric window itself has the same thickness in all areas. It uses the dielectric window configured in. The pattern of the slot pair has the same configuration as that shown in FIG. 2, and the other configurations have the same configuration as that shown in FIG. 1, and the reference numerals in FIG.
The same reference numerals as those in FIG. 1 indicate the same components unless otherwise specified.

A dielectric window 604 which is a microwave introduction window.
Can be made of the following materials similar to the dielectric window 104 shown in FIG. When a quartz plate having a thickness of 50 mm is used, for example, the vacuum side of the dielectric window 604 is made concave in the region (D6) up to φ = 60 mm, and the substrate 6
Regarding the distance from 13 to the dielectric window directly above the substrate having a diameter (Dw) of 200 mm, the distance (L62) is set to 65 mm in the region (D6) in which the radius of the substrate is from 0 mm to 30 mm. In the area, the distance (L61) is set to 60 mm. The pressure in the plasma processing container varies depending on process conditions, but is generally 0.1 Pa to 1000 Pa, preferably 5 Pa to
A desired effect can be obtained in the range of 1000 Pa. The distance between the lower surface of the dielectric window and the upper surface of the substrate (L11,
L41, L51, L52, L61, L62) is generally preferably in the range of 30 mm to 120 mm due to the relationship of plasma density, oxidation rate, film thickness distribution uniformity, and the like.

When the thickness of the dielectric window is changed within a predetermined range as described above, it is desirable to set the thickness to about λg / 4 of the wavelength (λg) of the microwave in the dielectric. Since the electric field strength of the microwaves is interspersed depending on the condition of the standing waves existing therein, if the central portion has the optimum thickness, the plasma density becomes low in the thin outer peripheral portion. This is because merely thinning the thickness of the dielectric window does not necessarily increase the electric field strength in the thin portion. Therefore, as in the present invention, it is effective to define the thickness of the central portion and provide a step of λg / 4 of the wavelength of the microwave in the dielectric body. The range in which the thickness of the dielectric window is changed or the range in which a step is formed may be arranged in a concentric ring shape or may be arranged in an appropriate distribution.

In order to generate a high density plasma, the frequency of the microwave to be injected is generally 2 GHz to 10 GHz.
In order to appropriately select from within the range of GHz and to make the plasma density immediately below the dielectric window reach the cutoff density of microwaves, the applied power is preferably relative to the area of the lower surface of the dielectric window. good to carry out a process appropriately selected from the range of ^{1W / cm 2 ~5W / cm 2} . As the process gas, a deposited film (insulating film, semiconductor film, metal film, etc.) is formed, a thin film (silicon semiconductor thin film, silicon compound thin film, metal thin film, metal compound thin film, etc.) is formed by a CVD method, Various known gases can be appropriately selected and used, though they differ depending on processes such as etching, ashing removal of organic components on the substrate surface, oxidation treatment of the substrate surface, and cleaning of organic substances on the substrate surface. For example, at least 8.5 × 10 ⁻² Pa · m ³ / sec or more in total may be introduced into the process by using one or more known gases.

The substrate support stage temperature varies depending on each process such as etching and film formation, but is generally -40.
It may be appropriately selected from the range of ℃ to 600 ℃. The substrate to be treated is not particularly limited, and is not limited to a semiconductor substrate, for example, a glass substrate, a plastic substrate, AlTiC.
A substrate or the like can be used. The dielectric constituting the microwave introduction window is not particularly limited as long as the material has sufficient mechanical strength and extremely low dielectric loss so that the microwave transmittance is sufficiently high. Alumina (sapphire), aluminum nitride, silicon nitride, fluorocarbon polymer or the like can be used.

[0034]

Embodiments of the present invention will now be described in more detail with reference to the drawings. (Embodiment 1) In the antenna means 102 of the apparatus shown in FIG. 1, the case where the antenna means equipped with the microwave radiation plate 103 of the present invention shown in FIG. 2 is used, and the antenna means 102 is shown in FIG. Conventional microwave radiation plate 3
No. 03 (slot pair 303a, 303b) is used, in order to compare and evaluate the stability of the two plasmas to be generated, the plasma is ignited and then the plasma blinks or a large tuner displacement is observed. I measured the time to get there.

The above evaluation is based on the microwave radiation plates 103, 3
This was carried out using the apparatus shown in FIG. 1 which used the same constituent elements except the antenna means on which each No. 03 was mounted. The conventional antenna means has a thickness of 4 mm inside the antenna.
The alumina dielectric disc of Fig. 3 has been inserted, and Fig. 3
Slot pairs 303a, 3 of three concentric circles as shown in FIG.
A microwave radiating plate 303 having a diameter of 336 mm and a thickness of 0.3 mm cut with 03b was used. On the other hand, in the antenna of the present invention, a dielectric is not inserted inside the antenna means 102, and the inside is formed as an air layer having a thickness of 15 mm, and a pair of slots 103a and 103b for one round as shown in FIG.
A microwave radiating plate 103 having a cut diameter of 336 mm and a thickness of 1 mm was used.

A quartz plate was placed as the substrate 113 on the substrate electrode 114, and no substrate bias was applied. Ar gas was introduced into the processing container 101 from the gas supply means 110 in a standard state at 0.5 Pa · m ³ / sec (300 sccm),
By the exhaust pump system 111 and the pressure regulating valve 112, the pressure inside the processing container 101 is adjusted to 20 Pa and 133 P.
Adjusted to a. After the pressure adjustment was completed, microwave power was introduced at a stroke with an output of 2.5 kW to generate plasma.

The time required until the plasma generated as described above becomes unstable is summarized in Table 2 below. (Table 2) From the results of Table 2, it can be seen that in the case of the antenna means of the present invention, the stability of plasma caused by the antenna is significantly improved.

(Embodiment 2) In order to compare the efficiency of introducing the microwave power of the antenna into the plasma, it is necessary to ignite plasma by using the same conventional antenna means as in Embodiment 1 and the antenna means of the present invention. The lower limits of the microwave power and the discharge sustaining power after plasma ignition were investigated.
A quartz plate is placed as the substrate 113 on the substrate electrode 114,
No substrate bias was applied. Ar gas from the gas supply means 110 to the processing container 101 in a standard state of 0.5 Pa.
After introducing m ³ / sec (300 sccm), the pressure in the processing container 101 was adjusted to 133 Pa by the exhaust pump system 111 and the pressure adjusting valve 112. After the pressure adjustment is finished, the microwave power is increased, that is,
While observing the potentiometer, microwave power was gradually introduced from an output of 0.0 kW, the output was increased until the plasma was ignited, and the discharge start power was examined. Also, the output was temporarily increased to 2.0 kW even after the plasma was ignited, and then the output was decreased to examine the output when the discharge disappeared.

The results of the discharge starting power and the discharge maintaining minimum power thus obtained are summarized in Table 3 below. (Table 3) From the results shown in Table 3, in the case of the antenna means of the present invention, the discharge characteristics are almost equal to those of the conventional antenna means, so that the thickness of the microwave radiation plate is increased (conventional radiation plate thickness: 0. 3 mm, the radiation plate thickness of the present invention is 1.0 mm)
It can be seen that there is almost no effect.

(Embodiment 3) In the conventional antenna means, the microwave radiation plate has the same pattern as in FIG. 3 and only the thickness is 1.0 mm. The maintenance minimum power was investigated. As a result, no discharge occurred even if the microwave output was turned on at 2.0 kW or more. From this fact, not only the influence of the reduction of the transmitted power by the calculation as shown in Table 1 but also strictly speaking, since the dielectric is not inserted within the slot thickness of 1.0 mm, the microwave radiation plate It can be seen that the microwave is almost shielded by the thickness of the.

Example 4 Oxidation of a processed wafer after direct oxidation of a silicon substrate by generating Kr / O ₂ plasma using the apparatus of the present invention shown in FIGS. 1, 2, 4, 5, and 6. The measurement of the film thickness will be described. First, the oxidation treatment of the silicon substrate performed using the apparatus shown in FIGS. 1 and 2 will be described. The dielectric window 104 is installed in the microwave introduction window, and the silicon substrate 113 is placed in the vacuum processing container 1.
Then, the microwave was output from the magnetron 106 to generate plasma under the following conditions, and the thickness of the oxide film on the silicon substrate 113 after plasma oxidation was measured by an ellipsometer. The microwave radiation plate used in Examples 1 to 3 and shown in FIG. 2 was used.

As the dielectric window 104, a diameter of 380 mm
(Vacuum container side: 350 mm), 50 mm thick quartz plate (dielectric constant 3.8, dielectric loss <1.0 × 10 ⁻⁴ @ 2.4)
5 GHz) was installed. Microwave frequency: 2.45
Output power in GHz: 2.5 kW (about 2.6 W / cm ² ), the hot plate temperature was maintained at 400 ° C., and the distance (L11) between the upper surface of the silicon substrate 113 and the lower surface of the dielectric window 104 was 60 mm. As a result, the silicon substrate 113 on the substrate electrode 114 was subjected to plasma treatment without applying a high frequency bias. As a plasma excitation gas, Kr is 0.5 Pa · m ³ / sec and O ₂ is 1.7x
Supplying 10 ⁻² Pa · m ³ / sec, pressure adjusting valve 112
The pressure in the processing container 101 was adjusted to 133 Pa, and the wafer was discharged for 10 minutes to perform plasma oxidation processing on the wafer.

Further, the plasma processing was performed under the same conditions as described above except that the pressure inside the processing container 101 was adjusted to 80 Pa by the pressure adjusting valve 112. As a result, the thickness distribution of the silicon oxide film formed on the substrate was almost concentric. FIG. 7 shows the average thickness in the radial direction. Figure 7
From the above, it is understood that in the case of 80 Pa, the outer peripheral portion on the substrate has a larger film thickness than in the central portion and the oxidation rate is faster, whereas in the case of 133 Pa, the central portion has a higher oxidation rate.

Next, using the apparatus shown in FIG. 4, the silicon substrate 4 is subjected to the same conditions as in the case of the apparatus shown in FIGS.
13 is plasma-oxidized, oxide film (silicon oxide film)
Was measured with an ellipsometer. As a result, the thickness distribution of the silicon oxide film formed on the substrate was almost concentric and uniform. FIG. 8 shows the average thickness in the radial direction. Comparing this result with FIG. 7, from the thickness distribution of the oxide film in the case of 80 Pa, the outer peripheral portion still has a higher oxidation rate than the central portion, but the difference is smaller, and the distribution uniformity is improved. You can see that In addition, the rate of formation of the oxide film is high as a whole. From this,
It can be seen that by changing the shape of the dielectric window, the microwave power can be efficiently supplied to the plasma and the distribution uniformity is improved. Also in the case of 133 Pa, the oxidation rate is generally high, and the same can be said as in the case of 80 Pa.

Further, using the apparatus shown in FIGS. 5 and 6, the silicon substrates 513 and 613 are plasma-oxidized under the same conditions as in the case of the apparatus shown in FIGS. 1 and 2 to form an oxide film (silicon oxide film). The thickness was measured by an ellipsometer. As a result, in the case of the device shown in FIG. 5, the thickness distribution of the silicon oxide film formed on the substrate was substantially concentric and uniform. FIG. 9 shows the average thickness in the radial direction. Comparing this result with FIG. 7, it can be seen from the thickness distribution of the oxide film in the case of 80 Pa that the central part has a higher oxidation rate than the outer peripheral part, contrary to the case of FIG. This is the distance (L5) to the dielectric window (plasma generation region) in the range of the radius of the silicon substrate from 0 mm to 30 mm.
This is because the density of the plasma reaching the substrate is higher than that in the other range (distance: L51) due to the short 2). Therefore, by increasing the distance from the lower surface of the dielectric window on the vacuum side to the substrate in each area, the film formation rate in that area is increased, and by adjusting the distance, the uniformity of the film thickness distribution is improved. I can do things.

Further, in the case of the device shown in FIG. 6, the thickness distribution of the silicon oxide film formed on the substrate was substantially concentric and uniform. FIG. 10 shows the average thickness in the radial direction.
Comparing this result with FIG. 7, it can be seen from the thickness distribution of the oxide film in the case of 80 Pa that the oxidation rate in the central portion is improved in the direction of increasing and the uniformity is improved. On the other hand, at 133 Pa, on the contrary, the oxidation rate in the outer peripheral portion is improved in the direction of increasing, and the uniformity is improved. At first glance, this contradicts the above result, but under the high pressure condition of 133 Pa, plasma tends to be concentrated in the central portion even when the planar dielectric window 104 (FIG. 1) is used. However, in the central part of the substrate, the distance (L62) to the dielectric window (plasma generation region) is 5 compared to other regions (distance: L61).
Since the distance is mm, it is considered that the density of the plasma reaching the substrate is thinner than other ranges, and the distribution is improved. On the contrary, at a low pressure of 80 Pa, the plasma density tends to spread because the plasma density is low. However, by making a part of the surface where the surface wave is generated concave, the plasma generation in the concave region increases, and It is considered that the stable coupling mode is less affected by the pressure condition. Therefore, the spread of plasma is suppressed, and a distribution close to that under the high pressure condition is obtained.

As described above, the unevenness is formed on both surfaces of the dielectric window in each region, so that the power of the microwave is intentionally concentrated in this region to generate plasma with less pressure dependence and good uniformity. Became possible. In the above example,
Plasma-oxidizing the silicon substrate using the microwave plasma processing apparatus shown in FIGS. 1, 2, 4, 5 and 6,
An oxide film was formed, but using the same plasma processing equipment,
Performing steps such as film formation, etching, improvement / modification of film composition, and ashing on a substrate that is an object to be processed in semiconductor LSI fabrication using a known thin film forming gas, etchant gas, ashing gas, etc. I was able to.

[0048]

As described in detail above, according to the present invention, a microwave radiation plate thicker than the conventional one is used in consideration of the thermal strength and mechanical strength of the microwave radiation plate. At the same time, in order to efficiently radiate microwaves even with this thick radiation plate, no dielectric is inserted in the microwave waveguide from the microwave oscillator to the microwave transparent dielectric window, and Provided is a plasma processing apparatus that uses an antenna means devised so that the wavelength inside the waveguide is set to the atmospheric state and the wavelength inside the antenna is made longer than before. By performing plasma processing using this apparatus, microwave processing is performed. Instability of plasma due to strain of the plate is eliminated, and a highly stable process can be performed. Further, according to the plasma processing apparatus of the present invention, the structure is simplified, it is not necessary to use expensive ceramic plates and Teflon or ceramic insulators that support the inner shaft of the coaxial tube, which may be damaged. This processing device can be manufactured in a short period with a simple structure.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration example of a microwave plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view schematically showing an example of an antenna pattern of a microwave radiating plate used as antenna means in the microwave plasma processing apparatus according to the present invention.

FIG. 3 is a plan view schematically showing an example of an antenna pattern of a microwave radiation plate used for a conventional antenna means in the microwave plasma processing apparatus according to the present invention.

FIG. 4 is a schematic cross-sectional view showing the configuration of a microwave plasma processing apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view showing the configuration of a microwave plasma processing apparatus according to another embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view showing the configuration of a microwave plasma processing apparatus according to still another embodiment of the present invention.

7 is a graph showing the average thickness in the radial direction of a silicon oxide film formed using the apparatus shown in FIG.

8 is a graph showing an average radial thickness of a silicon oxide film formed by using the apparatus shown in FIG.

9 is a graph showing the average radial thickness of a silicon oxide film formed using the apparatus shown in FIG.

10 is a graph showing the average radial thickness of a silicon oxide film formed using the apparatus shown in FIG.

[Explanation of symbols]

101 plasma processing container main body 102 coaxial waveguide converter and antenna 103 microwave radiating plate 104 vacuum sealing dielectric window 105 plasma 106 magnetron 107 isolator 108 tuner 109 waveguide 110 gas supply means 111 exhaust pump system 112 pressure regulating valve 113 Substrate 103a, 10
3b Slot 114 Substrate electrode 115 High frequency power supply for substrate electrode 116 Matching device for substrate electrode 117 Sleeve 303 Microwave radiation plate 303a, 30
3b Slot 404 Dielectric plate window 413 Substrate L41 Dielectric plate window-distance between substrates Dw Substrate area D4 Dielectric plate window thickness change area 504 Dielectric plate window 513 Substrate L51 Dielectric plate window-distance between substrates L52 Dielectric plate Window-substrate distance (thickness changing part) D5 Dielectric plate window thickness changing region 604 Dielectric plate window 613 Substrate L61 Dielectric plate window-substrate distance L62 Dielectric plate window-substrate distance (shape changing part) D6 Dielectric window thickness change area

Continued front page    F-term (reference) 4K030 FA01 JA01 JA09 JA16 JA18                       KA15 LA15                 5F045 AA09 AB32 AC11 AC16 DP04                       EH02 EH03

Claims (11)

[Claims] 1. An exhaust means for reducing the pressure in the microwave plasma processing container, a gas supply means for supplying a gas for exciting plasma into the processing container, and a wall surface of the processing container. A microwave transparent dielectric window,
Antenna means provided on the microwave introduction surface side of the dielectric window, the antenna means having a microwave radiating plate having a slot, and a microwave generation means provided upstream of the antenna means. In the microwave plasma processing apparatus, which is configured so that a substrate is installed in the processing container facing the dielectric window, the inside of the antenna means is inserted to shorten the wavelength in the tube. A microwave radiating plate of the antenna means is provided with a plurality of pairs of slots having different directions and arranged in a circle for only one round. Plasma processing equipment. 2. The microwave plasma processing apparatus according to claim 1, wherein the microwave radiation plate of the antenna means has a thickness of 0.5 mm or more and 3.0 mm or less. 3. The length of the slot is about 1 / wavelength in the tube.
2. The microwave plasma processing apparatus according to claim 1 or 2, wherein the width is 2 mm or more and 8 mm or less. 4. The dielectric window has a ring-shaped sleeve on the outer periphery of the surface on the processing container side so that the plasma excitation region does not directly contact the metal surface of the processing container wall. The microwave plasma processing apparatus according to claim 1, wherein the microwave plasma processing apparatus is a microwave plasma processing apparatus. 5. The surface shape and thickness of the central portion of the dielectric window are adjusted in-plane so that a region of the dielectric window corresponding to a predetermined region of the substrate has a thickness different from other regions. The microwave plasma processing apparatus according to any one of claims 1 to 4, wherein the microwave plasma processing apparatus is configured to have. 6. The dielectric window is provided on one of the processing container side surface and the microwave introduction side surface of the dielectric window.
A convex portion is provided in the region of the dielectric window corresponding to the predetermined region of the substrate, and the thickness of the region of the dielectric window corresponding to the predetermined region of the substrate is thicker than the thickness of the other regions. Or a concave portion is also provided in the area corresponding to the convex portion on the surface opposite to the surface on which the convex portion is provided, and the thickness of the area where the convex portion and the concave portion are provided is The microwave plasma processing apparatus according to any one of claims 1 to 4, wherein the microwave plasma processing apparatus is configured to have the same thickness as the region. 7. The dielectric window is formed by providing concentric steps on a surface of the dielectric window on the processing container side so that the distance from the surface of the substrate to the surface of the dielectric window varies depending on the region of the substrate. The plasma density is configured to be uniform on the substrate.
4. The microwave plasma processing device according to any one of 4 above. 8. The concentric steps of the dielectric window are discontinuously provided in the radial direction of the dielectric window with a diameter that is an integral multiple of 1/2 wavelength. Microwave plasma processing equipment. 9. The dielectric window has a central region having a different thickness from other regions, a region having a convex portion, and a region having concentric steps, and the thickness of these regions is different. 9. The microwave plasma processing apparatus according to claim 1, wherein is about 1/4 of the wavelength of the microwave in the dielectric. 10. A microwave plasma processing container is supplied with a raw material gas for exciting plasma by a gas supply means, and an exhaust pump exhausts the raw material and reaction by-product gas to reduce the pressure in the container to generate microwaves. The microwave oscillated and amplified by the means is introduced into the antenna means having the microwave radiating plate in which the slot is formed and radiated through the slot, and the radiated microwave is decompressed through the microwave transmitting window in the atmosphere of the introduction gas. The plasma processing method, which comprises introducing into the processing container, plasma is generated in the processing container by the electromagnetic field created by the microwave, and the substrate provided facing the dielectric window is subjected to microwave plasma processing. It is characterized in that plasma processing is performed using the microwave plasma processing apparatus according to any one of claims 1 to 9. Microwave plasma processing method. 11. The pressure of the gas in the processing container is 0.1.
It is Pa-1000Pa and the frequency of the microwave applied to an electrode is 2 GHz-10 GHz, The microwave plasma processing method of Claim 10 characterized by the above-mentioned.