JP2003059919A - Apparatus and method for microwave plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for microwave plasma treatment wherein uniform plasma density is attained on the surfaces of substrates and efficient plasma treatment is performed with reliability and stability. SOLUTION: A dielectric window which has an annular sleeve on the periphery thereof and wherein the surface shape and the thickness of the central portion thereof are adjusted in plane is used for a dielectric window placed directly above the surface of a substrate. This in-plane adjustment is made by forming stepped portions by forming projected portions in areas of the dielectric window corresponding to a specified range of the radius in the substrate, or forming recessed portions in areas corresponding to the projected portions on the surface opposite the surface on which the projected portions are formed. The thickness of the portions of the dielectric window subjected to the in-plane adjustment is approx. 1/4 of the wavelength of microwaves in the dielectric, and the portions subjected to the in-plane adjustment are discontinuously formed in the direction of the radius of the dielectric window with a diameter equivalent to an integral multiple of 1/2 the wavelength.

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 to 0.5 W / cm ^{2 to 20} W. A microwave plasma processing apparatus having a microwave introduction window with a high power density of / cm ² , film formation, etching, improvement / modification of film composition on a substrate which is an object to be processed in semiconductor LSI fabrication,
The present invention relates to a microwave plasma processing apparatus capable of performing 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 plasma processing such as CVD, etching and ashing, a DC or high frequency excited plasma source 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. In addition, since the plasma potential is as high as about 20 eV, metal contamination occurs due to sputtering of the chamber wall, and 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, a radial line slot antenna
(Hereinafter, referred to as RLSA) using an antenna means such as
A method has been developed in which microwaves are introduced into a vacuum atmosphere from a slot through a dielectric and a strong microwave electric field is generated to generate surface wave plasma. For example, Japanese Patent Laid-Open No. 2000-294548 describes a method in which the thickness of the dielectric window is continuously changed. In this method, circularly polarized microwaves are radiated by the slot pattern of the antenna, so uniform plasma with a large diameter can be generated, and since the frequency is high, low-temperature and high-density plasma can be generated, and high-speed It is said that good quality plasma processing can be realized.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the prior art described in Japanese Patent No. 94548, the microwave is
Propagating in a certain mode in the waveguide and being radiated from the antenna means to create a microwave electric field in the vacuum container, thereby forming plasma.However, when the plasma becomes dense, energy absorption occurs and at the same time, plasma is generated. The microwave is reflected on the surface, and an unspecified number of modes are generated between the antenna surface sandwiching the dielectric and the plasma excitation part. As described above, when the thickness of the dielectric window is continuously changed and the surface on the plasma processing chamber side is formed into a conical shape, there is a problem in mode stability and the like.

This reflected wave is divided into a mode in which it is attenuated and a mode in which it is amplified as a cavity resonator between the antenna surface and the plasma excitation part. However, when the reflected wave interferes with the introduced microwave and is attenuated, the power supply to the plasma is not stable and the plasma becomes unstable. As a result, there were problems that the reflected wave could not be suppressed by the tuner, auto matching always shook, and the plasma flickers.

Further, since the microwave has a high frequency, the power tends to concentrate on a certain part of the plasma as the part of the plasma has a lower impedance. In addition, a surface wave mode is formed in the radial direction, which is the most stable state due to the combination of many modes, but if the balance of the plasma impedance is lost due to aging, a mode jump occurs and the plasma distribution There was a problem that the reproducibility of was not obtained. In addition, this surface wave mode greatly depends on the process pressure, and low pressure (about 5 to 100 Pa)
There is a phenomenon in which the plasma density distribution is reversed at the central part and the outer peripheral part at high pressure (100 Pa and above).

An object of the present invention is to solve the above-mentioned problems of the prior art, and it is possible to obtain a uniform plasma density on the substrate surface, and to perform highly efficient plasma treatment with high reliability and stability. It is to provide a microwave plasma processing apparatus and a processing method using this apparatus.

[0008]

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
A microwave transparent dielectric window provided on the wall surface of the processing container, an antenna means provided on the microwave introduction side of the dielectric window, and a microwave generation means provided upstream of the antenna means. In the microwave plasma processing apparatus, wherein the substrate is placed in the processing container so as to face the dielectric window, the dielectric window provided immediately above the substrate surface is A ring-shaped sleeve is provided on the outer peripheral portion 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.

In the microwave-excited plasma processing apparatus of the present invention, the dielectric window provided directly above the substrate surface is further adjusted in-plane with respect to the surface shape and thickness of the central portion,
It is preferable that a region corresponding to a predetermined range of the radius in the substrate is configured to have a different thickness from other regions. The dielectric window also has a convex portion provided on a region corresponding to a predetermined range of the radius in the substrate on one of the surface on the processing container side and the surface on the microwave introduction side, The thickness of a region corresponding to a predetermined range of the radius is thicker than the thickness of other regions, or the convex portion on the surface opposite to the surface on which the convex portion is provided. It is preferable that the region is provided with a recess and the thickness of the region where the protrusion and the recess are provided is the same as the thickness of the other regions. In the above processing apparatus, by providing concentric steps on the dielectric window so that the distance from the substrate surface to the surface of the dielectric window varies depending on the radius range within the substrate, the density of the generated plasma is uniform on the substrate. Is preferable.

It is preferable that 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. In addition, the dielectric window, a region having a different thickness in the central portion, a region having a convex portion,
It is preferable to have a region having concentric steps, and the thickness of the region is about 1/4 of the wavelength of the microwave in the dielectric. According to the microwave plasma processing apparatus of the present invention, a large-diameter dielectric window, for example, a dielectric window having a diameter of 250 mm or more or having an area equal to or larger than a circle having a diameter of 250 mm is used, and a large power density It is possible to introduce microwaves.

The microwave plasma processing method of the present invention comprises:
A raw material gas for exciting plasma is supplied by a gas supply means into the microwave plasma processing container, the raw material and a reaction by-product gas are exhausted by an exhaust pump to reduce the pressure inside the container, and the microwave generation means oscillates and amplifies. The microwaves introduced are introduced into the antenna means and radiated through the slot, and the radiated microwaves are introduced into the processing container under a vacuum atmosphere through the microwave transmission window and processed by the electromagnetic field created by the microwaves. Plasma is generated in the container, and the substrate provided facing the dielectric window is subjected to microwave plasma processing. Plasma is generated using the plasma processing apparatus having the dielectric window configured as described above. To process. The gas pressure in the processing container is 0.1 Pa to 1
The frequency of the microwave applied to the electrodes 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. Also, the frequency is 2
If it is less than GHz, the desired plasma density cannot be obtained, and 1
If the frequency exceeds 0 GHz, the equipment for power amplification becomes large and the handling thereof is difficult.

According to the present invention, in the microwave plasma processing apparatus, the surface shape and thickness of the dielectric window are adjusted in-plane as described above, and the supplied microwave and reflected wave are amplified in the resonator. By forming a region and a region not so, the power is efficiently concentrated in the amplified region,
Further, since the occurrence of mode jump can be suppressed by limiting the surface wave mode that is stable in space, a highly efficient process with high reliability and stability can be performed. Further, the plasma is excited in a region separated from the surface of the dielectric window within a few millimeters, and reaches the opposing substrate by diffusion. The attenuation of the plasma density due to this diffusion is approximately proportional to the square of the distance. A uniform plasma density can be obtained on the substrate surface by forming a step in the shape of the dielectric window so that the dielectric portion corresponding to the region of low plasma density approaches the substrate side.

[0013]

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. As a first embodiment of the present invention, FIG. 1 shows a schematic configuration of a microwave plasma processing apparatus for semiconductor substrates using RLSA, which is provided with a microwave transmission window having a ring-shaped sleeve on the outer peripheral portion. FIG.

In FIG. 1, 101 is a processing container for performing plasma processing, 102 is a coaxial waveguide converter and antenna means, 103 is a slot for radiating microwaves, 1
Reference numeral 04 is a microwave transparent dielectric window, 105 is plasma formed by a microwave electric field above the substrate for etching and film formation, 106 is a magnetron for oscillating microwaves, 107 is an isolator, 108 is a 4E tuner, Reference numeral 109 is a waveguide, 110 is a plasma forming gas supply means, 111 is an exhaust pump, 112 is a pressure adjusting valve for adjusting the pressure in the container 101, 113 is a substrate to be plasma-processed, and 114 is a substrate. Electrodes 115 are high-frequency power supplies for applying high frequencies to the substrate electrodes 114 and substrate 113 as needed, and 116 are matching devices for adjusting high-frequency impedance. Dielectric window 104
A ring-shaped sleeve 117 is formed in the outer peripheral portion, that is, in the portion away from the central portion so that the plasma excitation region does not directly contact the metal surface of the processing container wall.

The outline of the plasma processing method performed by using the apparatus shown in FIG. 1 will be described below. Processing container 101
A gas for exciting the plasma 105 is supplied to the inside by a gas supply means 110, an exhaust pump 111 is operated, and a raw material and a reaction by-product gas are exhausted to process the processing container 10.
The pressure inside 1 is reduced, and the process pressure inside the processing container 101 is adjusted by the pressure adjusting valve 112. Magnetron 106
The microwave oscillated and amplified by the 4E tuner 108
Is introduced into the antenna 102 through and is radiated from the slot 103. At this time, the reflected wave is 4E tuner 10
The reflected wave that is returned to the processing container 101 side by 8, but is not adjusted is absorbed by the isolator 107,
It prevents the return to the magnetron 106. The microwave radiated from the slot 103 is introduced into the inside of the processing container 101 in a vacuum atmosphere through the dielectric window 104,
Plasma 105 is formed in the processing container 101 by the electromagnetic field generated by the microwave.

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 some of them penetrates in the plasma within several millimeters. 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.

FIG. 2 shows a second embodiment of the present invention, R
FIG. 6 is a cross-sectional view showing a schematic configuration of an apparatus including a microwave transmission window having a convex portion on a surface on the antenna means side in the configuration of the microwave plasma processing apparatus for semiconductor substrates using LSA. In this device, as the dielectric window 204 constituting the microwave introduction window, in the area of a concentric circle, that is, in the area from the center of the circular dielectric window to a predetermined equal distance, on the atmosphere side (microwave introduction side). A convex portion (diameter: D2) is provided on the surface, and a dielectric window in which the thickness of the portion is changed is used. Other configurations are the same as those shown in FIG. 1, and the reference numerals in the drawings are unless otherwise specified.
The same reference numerals as those in FIG. 1 indicate the same configurations.

Dielectric window 204 which is a microwave introduction window
Can be made of the same material as the dielectric window 104. When using a quartz plate having a thickness of 50 mm, for example, φ =
Dielectric window 2 in the area (D2) up to 95 mm
The atmosphere side of 04 is convex, and the thickness of the convex part is 60 m.
It is set to m. For example, the thickness of the dielectric window directly above the silicon substrate having a diameter (Dw) of 200 mm is the thickness of the region immediately above it in the region where the radius of the substrate is from 0 mm to 47.5 mm (D2X1 / 2). 60 mm
And the thickness in other regions becomes 50 mm.

FIG. 5 shows a third embodiment of the present invention, R
FIG. 3 is a cross-sectional view showing a schematic configuration of a microwave plasma processing apparatus for semiconductor substrates using LSA, which is provided with a microwave transmission window having a convex portion on a surface on the processing container 101 side. In this device, as the dielectric window 504 forming the microwave introduction window, the surface on the vacuum side is opposite to the case of FIG. 2 in a concentric region, that is, a region from the center of the dielectric window to a predetermined equal distance. Convex part (diameter: D
5) is provided, and the dielectric window in which the thickness of the portion is changed is used. Other configurations are the same as those shown in FIG. 1, and the same reference numerals as those in FIG. 1 indicate the same configurations unless otherwise specified.

A dielectric window 504 which is a microwave introduction window.
Can be made of the same material as the dielectric window 104. When using a quartz plate with a thickness of 44 mm, for example, φ =
Dielectric window 5 in the area (D5) up to 60 mm
The vacuum side of 04 is convex, and the thickness of the convex part is 60 m.
It is set to m. For example, the thickness of the dielectric window directly above the silicon substrate having a diameter (Dw) of 200 mm is the thickness of the region located immediately above it in the region where the radius of the substrate is in the range of 0 mm to 30 mm (D5X1 / 2). The thickness is 60 mm, and the thickness in other areas is 44 mm. In addition, the area of the substrate radius from 0 mm to 30 mm (D5
X1 / 2), the distance from the substrate to the dielectric plate (L
52) is 40 mm, and the distance (L51) is 56 mm in other regions.

FIG. 6 shows R as a fourth embodiment of the present invention.
In the structure of a microwave plasma processing apparatus for a semiconductor substrate using LSA, a microwave transmission in which a convex portion is provided on the surface on the processing container 101 side and a concave portion is provided in a region corresponding to the convex portion on the atmosphere side surface. It is sectional drawing which shows the schematic structure of the apparatus provided with the window. In this device, as a dielectric window 604 forming a microwave introduction window, a concentric region,
That is, in the region from the center of the dielectric window to a predetermined equal distance, processing is performed so that a convex portion is provided on the microwave introduction side surface and a concave portion is provided on the vacuum side surface. A dielectric window configured to have the same thickness is used. Other configurations are the same as those shown in FIG. 1, and the reference numerals in the drawings are unless otherwise specified.
The same reference numerals as those in FIG. 1 indicate the same configurations.

A dielectric window 604 which is a microwave introduction window.
Can be made of the same material as the dielectric window 104. When using a quartz plate having a thickness of 50 mm, for example, φ =
Dielectric window 6 in the area (D6) up to 60 mm
The vacuum side of 04 is made concave, and the diameter (Dw) from the substrate 613
Regarding the distance to the dielectric window directly above the substrate of 200 mm, the distance (L62) is 65 m in the region (D6) of the radius of the substrate from 0 mm to 30 mm.
m, and the distance (L61) in other regions is 60 mm. The pressure in the plasma processing container varies depending on process conditions, but is generally 5 Pa to 1
A desired effect can be obtained in the range of 000 Pa. The distance between the lower surface of the dielectric window and the upper surface of the substrate (L11, L
21, 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 temperature of the support stage of the substrate 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.

[0026]

Embodiments of the present invention will now be described in more detail with reference to the drawings. (Embodiment 1) The measurement of the thickness of the oxide film of the processed wafer after the Kr / O ₂ plasma is generated and the silicon substrate is directly oxidized by using the apparatus of the present invention shown in FIGS. 1 and 2 will be described. . First, the oxidation treatment of the silicon substrate using the apparatus shown in FIG. 1 will be described. The dielectric window 104 is installed on the microwave introduction window, and the silicon substrate 11
After setting No. 3 in the vacuum processing container 101, microwaves were output from the magnetron 106 to generate plasma under the following conditions, and the thickness of the oxide film of the silicon substrate 113 after plasma oxidation was measured by an ellipsometer.

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. In addition, the pressure control valve 112 allows the processing container 10
Plasma treatment was performed under the same conditions as above, except that the pressure inside 1 was adjusted to 80 Pa.

As a result, the distribution of the thickness of the silicon oxide film formed on the substrate was substantially concentric. FIG. 3 shows the average thickness in the radial direction. From FIG. 3, it can be seen 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. 2, the silicon substrate 213 is plasma-oxidized under the same conditions as those of the apparatus shown in FIG. 1, and the thickness of the oxide film (silicon oxide film) is measured by an ellipsometer. It was measured. As a result, the thickness distribution of the silicon oxide film formed on the substrate was almost concentric and uniform. FIG. 4 shows the average thickness in the radial direction. Comparing this result with FIG. 3, it can be seen from the thickness distribution of the oxide film in the case of 80 Pa that 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 formation rate of the oxide film is generally high. 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.

(Embodiment 2) Using the apparatus shown in FIG.
The measurement of the thickness of the oxide film of the processed wafer after the / O ₂ plasma is generated and the silicon substrate is directly oxidized will be described. The silicon substrate 513 was plasma-oxidized under the same conditions as in the case of the device shown in FIG. 1 described in Example 1, and the thickness of the oxide film was measured by an ellipsometer.

As a result, the thickness distribution of the silicon oxide film formed on the substrate became almost concentric and uniform. Figure 7
Shows the average thickness in the radial direction. Comparing this result with FIG. 3, it can be seen from FIG.
Contrary to the above case, it can be seen that the oxidation rate is higher in the central portion than in the outer peripheral portion. This is because the radius of the silicon substrate is 0
Since the distance (L52) to the dielectric window (plasma generation region) is short in the range from 30 mm to 30 mm, the density of plasma reaching the substrate is in another range (distance: L51)
Because it is higher. Therefore, by increasing the distance from the lower surface of the dielectric window on the vacuum side to the substrate in each region, the film formation rate in that region is increased, and by adjusting the distance, the film thickness distribution uniformity is improved. I can do things.

(Embodiment 3) Using the apparatus shown in FIG.
The measurement of the thickness of the oxide film of the processed wafer after the / O ₂ plasma is generated and the silicon substrate is directly oxidized will be described. The silicon substrate 613 was plasma-oxidized under the same conditions as in the case of the apparatus shown in FIG. 1 described in Example 1, and the thickness of the oxide film was measured by an ellipsometer.

As a result, the distribution of the thickness of the silicon oxide film formed on the substrate became almost concentric and uniform. Figure 8
Shows the average thickness in the radial direction. Comparing this result with FIG. 3, it can be seen from the film 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 increased. 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 results of the above-mentioned embodiment, 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, as in the result of Example 2, in the central portion of the substrate, the distance (L62) to the dielectric window (plasma generation region) is other region (distance: L6).
Since it is 5 mm farther than in 1), it is considered that the density of the plasma reaching the substrate is lower than in 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, unevenness processing is performed on both surfaces of the dielectric window in each region, so that the microwave power is intentionally concentrated in this region to generate plasma with little pressure dependence and good uniformity. Became possible. In the above example, the microwave plasma processing apparatus shown in FIGS. 1, 2, 5 and 6 was used to plasma-oxidize a silicon substrate to form an oxide film. However, the same plasma processing apparatus was used to fabricate a semiconductor LSI. It was possible to perform steps such as film formation, etching, improvement / modification of film composition, and ashing on the substrate which is the object to be processed in the known thin film forming gas, etchant gas, ashing gas, etc. .

[0035]

As described above in detail, according to the present invention, in the microwave plasma processing apparatus, the surface shape of the dielectric window and the thickness of the dielectric window are adjusted in-plane and the microwave is supplied. By forming a region where the reflected wave is amplified and a region where it is not amplified, the power can be efficiently concentrated in the amplified region, and the surface wave mode that is stable in space is limited. By doing so, it is possible to suppress the occurrence of mode jump, and it is possible to perform a highly efficient process with high reliability and stability. Plasma is excited in a region within a few millimeters from the dielectric window and reaches the opposing substrate by diffusion. The attenuation of the plasma density due to this diffusion is approximately proportional to the square of the distance. A uniform plasma density can be obtained on the substrate surface by forming a step so that the dielectric window in the low density region approaches the substrate side.

[Brief description of drawings]

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

FIG. 2 is a schematic sectional view showing a schematic configuration of a microwave plasma processing apparatus according to a second embodiment of the present invention.

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

FIG. 4 is a graph showing an average radial thickness of a silicon oxide film formed using the apparatus shown in FIG.

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

FIG. 6 is a schematic sectional view showing a schematic configuration of a microwave plasma processing apparatus according to a fourth 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 a radial average thickness of a silicon oxide film formed by using the apparatus shown in FIG.

[Explanation of symbols]

101 Plasma Processing Container 102 Coaxial Waveguide Converter and Antenna 103 Slot 104 Dielectric Plate 105 Plasma 106 Magnetron 107 Isolator 108 4E Tuner 109 Waveguide 110 Gas Supply Means 111 Exhaust Pump 112 Pressure Control Valve 113 Substrate 114 Substrate Electrode 115 Substrate Electrode High frequency power supply 116 Board electrode matching device 117 Sleeve 204 Dielectric plate 213 Substrate L21 Dielectric plate-distance between substrates Dw Substrate range D2 Dielectric plate thickness change range 504 Dielectric plate 513 Substrate L51 Dielectric plate-Substrate distance L52 Distance between dielectric plate and substrate (thickness changing part)
D5 Dielectric plate thickness change range 604 Dielectric plate 613 Substrate L61 Dielectric plate-distance between substrates L62 Dielectric plate-distance between substrates (shape change part)
D6 Dielectric thickness change range

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4G075 AA24 AA30 BC01 BC06 CA26                       EC30 EE02 FA05 FC15                 5F045 AA20 AB32 AC11 AC14 AD08                       AE19 AE21 AF03 BB02 DP04                       EH03 EH11 EH20 GB13

Claims (10)

[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,
An antenna means provided on the microwave introduction side of the dielectric window and a microwave generation means provided on the upstream side of the antenna means are provided, and a substrate is provided in the processing container facing the dielectric window. In the microwave plasma processing apparatus configured to be installed, the dielectric window provided directly above the substrate surface has a plasma excitation region directly on the processing chamber wall on the outer peripheral portion of the processing chamber side surface. A microwave plasma processing apparatus having a ring-shaped sleeve so as not to come into contact with the metal surface of. 2. The dielectric window provided right above the surface of the substrate further has a surface shape and a thickness of the central portion thereof adjusted in-plane so that a region corresponding to a predetermined range of a radius in the substrate is formed. The microwave plasma processing apparatus according to claim 1, wherein the microwave plasma processing apparatus has a thickness different from that of other regions. 3. The dielectric window provided directly above the surface of the substrate further has a predetermined range of a radius within the substrate on one of the processing container side surface and the microwave introduction side surface. Is provided such that the thickness of the region corresponding to a predetermined range of the radius in the substrate is thicker than the thickness of the other region, or the protrusion is provided. A concave portion is provided in the area corresponding to the convex portion on the surface opposite to the surface on which the concave portion is provided, and the thickness of the area where the convex portion and the concave portion are provided is the same as the thickness of the other areas. The microwave plasma processing apparatus according to claim 1, wherein the microwave plasma processing apparatus is a 4. A dielectric window provided directly above the surface of the substrate is provided with concentric steps so that the distance from the surface of the substrate to the surface of the dielectric window varies depending on the range of the radius within the substrate. 2. The microwave plasma processing apparatus according to claim 1, wherein the density of generated plasma is made uniform on the substrate. 5. The concentric steps of the dielectric window provided immediately above the surface of the substrate are discontinuously provided in the radial direction of the dielectric window with a diameter that is an integral multiple of 1/2 wavelength. The microwave plasma processing apparatus according to claim 4, wherein 6. A dielectric window provided directly above the surface of the substrate has regions having different thicknesses in the central portion, regions having convex portions, and regions having concentric steps, and The microwave plasma processing apparatus according to any one of claims 2 to 5, wherein the thickness of the region is about ¼ of the wavelength of the microwave in the dielectric body. 7. 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 and radiated through the slot, and the radiated microwave is introduced into the processing container under a vacuum atmosphere through the microwave transmission window, and the microwave Plasma is generated in the processing container by an electromagnetic field to be created, and the substrate provided facing the dielectric window is subjected to microwave plasma treatment. As the dielectric window provided immediately above the substrate surface, A ring-shaped sleeve is provided 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 surface shape and thickness of the central portion are adjusted in-plane so that the region corresponding to a predetermined range of the radius in the substrate has a thickness different from other regions, or On one surface of the surface on the processing container side and the surface on the microwave introduction side, a convex portion is provided in a region corresponding to a predetermined range of the radius in the substrate to correspond to the predetermined range of the radius in the substrate. The thickness of the area to be formed is thicker than the thickness of the other area, or a concave portion is 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 convex portion is formed. Which performs plasma processing using a plasma processing apparatus provided with a dielectric window configured such that the thickness of a region provided with a portion and a recess is the same as the thickness of other regions. Wave plasma processing method. 8. A plasma processing apparatus having a dielectric window in which concentric steps are provided discontinuously in the radial direction of the dielectric window with a diameter that is an integral multiple of ½ wavelength as the dielectric window. ,
8. The microwave plasma processing method according to claim 7, wherein the plasma processing is performed such that the density of the generated plasma is uniform on the substrate. 9. The dielectric window has regions having different thicknesses in the central portion, regions having convex portions, and regions having concentric steps, and the thickness of the region is defined in the dielectric body. 9. The microwave plasma processing method according to claim 7, wherein the plasma processing is performed by using a plasma processing apparatus provided with a dielectric window having a wavelength of about ¼ of the microwave wavelength. 10. The gas pressure 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 in any one of Claims 7-9 characterized by the above-mentioned.