JP3258441B2 - Microwave plasma processing apparatus and microwave plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus used in the manufacture of semiconductor devices, electronic circuits, etc., and more particularly, to a high-speed processing such as the formation of a high-performance thin film having good step coverage. The present invention relates to a plasma processing apparatus for performing the above.

[0002]

2. Description of the Related Art Semiconductor devices and electronic circuits, particularly, VLSI
In the manufacturing process, a plasma processing apparatus occupies an important position. SiN for final protective film or S for interlayer insulating film
A plasma CVD apparatus is used to form thin films such as iO ₂ , a sputtering apparatus is used to form Al thin films for wiring, an RIE apparatus is used to etch various thin films, and a plasma ashing apparatus is used to ash photoresist. In addition, applications to oxynitriding, cleaning, doping, and epitaxial processes are also being studied.

In recent years, SiH ₄ has been used as an interlayer insulating SiO ₂ film.
A plasma CVD method using an organic silane such as tetraethoxysilane (TEOS) as a raw material gas, which can form an SiO ₂ film having better step coverage than that of using GaN, has been used. An SiO ₂ film is formed.

[0004] Most of the plasma processing apparatuses put into practical use use a high frequency of 13.56 MHz or a microwave of 2.45 GHz as an excitation source and perform plasma processing by contacting a substrate with generated plasma. A large number of ions in the plasma are accelerated by a sheath electric field formed on the plasma contact surface and are incident on the substrate with energy of about several tens to 100 eV, so that damage and compressive stress are likely to be generated on the surface and the film of the substrate. When an organic source gas such as TEOS is used, an inappropriate reaction such as CH bond dissociation occurs, carbon is easily mixed into the film, and surface migration is difficult due to gas phase decomposition. Since it adheres to the substrate, the step coverage is reduced.

[0005] In order to solve these problems, an isolated plasma processing apparatus in which a plasma generation chamber and a plasma processing chamber are separated has been studied. Further, in order to further improve the quality, a thin film forming method using an optically assisted plasma CVD apparatus provided with a substrate surface light irradiation means in an isolated plasma processing apparatus is being studied (for example, J. Jpn. Appl. Phys. Vol. .
29, No. 12, 1990, pp. L2341).

This method comprises the steps of H, O, N, F, Cl, B
First gas containing no element other than r, He, Ne, Ar, Kr, Xe and Rn (O _{2 in} the case of an interlayer SiO ₂ film)
Is excited by the plasma generated by the high frequency, and H, O, N, F, supplied to the space isolated from the active species (oxygen radicals and the like) generated by the excitation and the plasma.
Cl, Br, He, Ne, Ar, Kr, Xe and Rn
Reacting with a second gas (organic silane in the case of an interlayer SiO ₂ film) composed of elements other than the above to form a reaction intermediate,
The reaction intermediate is deposited on a coated substrate placed in a space isolated from the plasma, and the substrate surface is irradiated with visible ultraviolet light absorbed by the attached reaction intermediate to desorb impurity and volatile components. This is a method of forming a thin film that suppresses gas phase decomposition of organic silane and adheres to the substrate in a state where surface migration is easy, so that step coverage is excellent, and desorption of volatile components due to photosurface reaction is promoted. Therefore, a high-quality thin film can be formed.

[0007] As a plasma source of these plasma CVD apparatuses and optically assisted plasma CVD apparatuses, a half of the guide wavelength is used.
Alternatively, use of slotted microwave waveguides (multi-slot antennas) formed at quarter wavelength intervals has been studied, and the plasma density and isolation are improved as compared with the use of other plasma sources. Formation and high-speed processing are possible, and particularly good step coverage is realized.

[0008]

However, in the above-mentioned conventional apparatus, when the waveguide is not linear (for example, cylindrical) or when the manufacturing dimensions are shifted, the guide wavelength changes slightly and matching can be obtained. There were no cases.

Accordingly, the present invention solves the above-mentioned problems of the prior art, and can easily perform matching even if the guide wavelength is slightly changed, and provide a microwave plasma processing having a plasma source capable of forming a high-density and highly isolated plasma. It is an object of the present invention to provide an apparatus and a processing method using the apparatus.

[0010]

Means for Solving the Problems The present invention provides at least:
(1) a plasma processing chamber; (2) means for evacuating the processing chamber to a vacuum; (3) means for supplying a processing gas into the processing chamber; In a plasma generation device having a microwave waveguide having a slit hole formed therein, and (5) a plasma processing apparatus having a means for holding a substrate to be processed, the plasma processing device has a means for changing a guide wavelength of the microwave waveguide. And a processing method using the same.

According to the present invention, by providing a guide wavelength adjusting means such as changing the dimension of the waveguide cross section, matching can be facilitated even when the guide wavelength is slightly changed, and high-density and highly isolated plasma can be generated. And high quality and high speed processing.

A plasma processing apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a diagram of a multi-slot antenna,
1A is a cross-sectional view, and FIG. 1B is a side view taken along line XX of FIG. 1A. In the figure, 1 is a multi-slot antenna, 2 is a slit hole formed inside the multi-slot antenna 1, 3
Are microwave inlets to the multi-slot antenna 1;
Is a propagation promoting material for promoting the introduction of microwaves into the inside of the multi-slot antenna 1;
A movable top plate for adjusting the in-tube wavelength of the movable top plate;
Is a moving mechanism for moving up and down.

A microwave is introduced into the multi-slot antenna 1 from the inlet 3 and leaks from the slit hole 2 to generate plasma inside. The reflection intensity from the multi-slot antenna 1 is monitored by a microwave intensity monitor such as a directional coupler (not shown), and the movable table 5 is moved by the table moving mechanism 6 so that the reflection intensity is minimized.

The microwave frequency used in the present invention is:
Choose an appropriate value in the range of 0.8 to 5 GHz (eg, commercial frequency 0.915 or 2.45 GHz).

The apparatus of the present invention can be applied to a plasma source other than the above-mentioned multi-slot antenna, as long as the plasma source changes in matching depending on the guide wavelength.

As the guide wavelength adjusting means of the apparatus of the present invention, any means capable of changing the guide wavelength, such as a means for changing the dimension of a waveguide such as a top plate moving, is applicable.

[0017]

(Embodiment 1) An embodiment in which the present invention is applied to a plasma CVD apparatus will be described with reference to FIG. In the figure, 1 is a multislot antenna, 5 is a multislot antenna 1
A movable top plate for adjusting the in-tube wavelength of the movable top plate;
, A moving mechanism for moving up and down, 7 is a film forming chamber, and 8 is S
a coated substrate 9 such as an i-substrate;
Is a heater for heating the coated substrate 8, 11 is an exhaust port, 12 is a first gas, 13 is a second gas, 14 is a quartz tube, and 15 is a porous diffusion plate.

First, the base 8 is placed on the support 9 and an electric current is supplied to the heater 10 to heat the base 8 from room temperature to a desired temperature of several hundred degrees centigrade. Next, the first gas 12 introduced through the plasma generation region and the second gas 13 introduced directly into the vicinity of the base body 8 are caused to flow, and a conductance valve (not shown) provided on the side of the exhaust port 11 is used.
Hold at the desired pressure of 0 Torr. Further, by introducing a microwave from the microwave inlet 3 to the multi-slot antenna 1, a plasma localized near the multi-slot antenna 1 is generated by the microwave leaking from the slit hole 2, and a desired film thickness can be obtained. The film is formed up to. During this time, the reflection intensity from the multi-slot antenna 1 is monitored by a microwave intensity monitor such as a directional coupler (not shown), and the movable top plate 5 is moved by the top moving mechanism 6 so that the reflection intensity is minimized. .

Specifically, N ₂ 2 is used as the first gas 12.
00 sccm, 20 sc of SiH ₄ as the second gas 13
cm, pressure 0.05 Torr, substrate temperature 300
Film formation was performed under the conditions of 500 ° C. and microwave power of 500 W.

As a result, a high-quality SiN film having a hydrogen content of 10 atm% and a stress of 2 × 10 ⁹ dyn / cm ² was formed at a high speed of 70 nm / min with little damage.

By changing the gas, SiN, SiO
₂ , insulator such as Ta ₂ O ₅ , Al ₂ O ₃ , AlN, a-S
i, semiconductor such as poly-Si, GaAs, Al, W
Metal such as can be formed.

(Embodiment 2) An embodiment in which the present invention is applied to a surface modification apparatus will be described.

Using the apparatus shown in FIG. 2, O ₂ (oxidizing gas) was supplied at 200 sccm as the first gas 12, the second gas 13 was not supplied, the pressure was 0.2 Torr, the substrate temperature was 500 ° C., and The microwave power was set to 500 W, the other conditions were the same as in Example 1, and the oxidation was performed by the same operation as in Example 1.

As a result, a high-quality S having a withstand voltage of 11 MV / cm was obtained.
The iO ₂ film was formed at a high speed of 1.5 nm / min with little damage at an interface charge density of 4 × 10 ¹⁰ / cm ² .

By changing the gas, Si, Al, T
Oxynitridation of i, Zn, Ta, etc., and doping of B, As, P, etc. are possible.

(Embodiment 3) An example in which the present invention is applied to a cleaning device will be described.

Using the apparatus shown in FIG. 2, CF ₄ + H ₂ was used as the first gas 13 at 50 sccm and 10 sccm, respectively.
Supply, no second gas, pressure 0.02 Torr
r, substrate temperature 300 ° C., microwave power 300 W,
Other conditions were the same as in Example 1, and the same operation as in Example 1 was performed. As a result, the natural oxide film on the Si substrate could be completely removed in one minute. By changing the gas, it is also possible to clean organic substances and heavy metals.

(Embodiment 4) An example in which the present invention is applied to an optically assisted plasma CVD apparatus will be described.

In this embodiment, the apparatus shown in FIG. 3 is used. In the figure, 7 is a reaction chamber, 8 is a substrate to be processed (coated substrate) such as a Si substrate, 9 is a support for the coated substrate 8, 10 is a heater for heating the coated substrate 8, 11 is an exhaust port, and 12 is a first port. , 13 is a second gas, 14 is a quartz tube, 15 is a porous diffusion plate, 16 is a light source, 17 is a reflector, 18 is an integrator, and 19 is a light introduction window.

First, the base 8 is placed on the support 9, and the light from the light source 16 is applied to the base 8,
To heat the substrate 8 from room temperature to a desired temperature of several hundred degrees Celsius. Next, the first gas 12 introduced through the plasma generation region and the second gas 13 introduced directly into the vicinity of the base body 8 are caused to flow, and a conductance valve (not shown) provided on the side of the exhaust port 11 is used. 0To
Hold at the desired pressure of rr. Further, by introducing a microwave from the microwave inlet 3 to the multi-slot antenna 1, a plasma localized near the multi-slot antenna 1 is generated by the microwave leaking from the slit hole 2, and a desired film thickness can be obtained. The film is formed up to. During this time, the reflection intensity from the multi-slot antenna 1 is monitored by a microwave intensity monitor such as a directional coupler (not shown), and the movable top plate 5 is moved by the top moving mechanism 6 so that the reflection intensity is minimized. .

Specifically, the first gas 12 is O_TwoTo
2 slm, 500 sc of TEOS as the second gas 13
cm, pressure 0.1 Torr, light illuminance 0.6 W /
cm ^TwoSubstrate temperature 300 ° C, microwave power 1kW
The film was formed in this condition.

As a result, a high-quality and flat SiO ₂ film was formed at a high speed of 180 nm / min with a hydrogen content of 1 atm% or less, a stress of 2 × 10 ⁸ dyn / cm ^2, and a tensile force of 2 × 10 ⁸ dyn / cm ² .

By changing the gas, SiN, SiO
₂ , insulator such as Ta ₂ O ₅ , Al ₂ O ₃ , AlN, a-S
i, semiconductor such as poly-Si, GaAs, Al, W
Metal such as can be formed.

[0034]

As described above, by providing the guide wavelength adjusting means for changing the cross-sectional dimension of the waveguide, matching can be easily achieved even if the guide wavelength is slightly changed, and high density and high density can be obtained. Isolation plasma can be generated, and processing such as high-performance thin film formation excellent in performance such as step coverage can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a multi-slot antenna according to an embodiment of the present invention, wherein A is a schematic cross-sectional view of the multi-slot antenna, and B is a XX side view of A.

FIG. 2 is a schematic sectional view of a microwave-isolated plasma processing apparatus according to one embodiment of the present invention.

FIG. 3 is a schematic sectional view of an optically assisted plasma processing apparatus according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-slot antenna 2 Slit hole 3 Microwave introduction port 4 Microwave propagation promoting material 5 Movable top plate 6 Movable mechanism of movable top plate 7 Processing chamber (reaction chamber) 8 Substrate to be processed 9 Substrate of substrate to be processed 10 Heater 11 Exhaust Mouth 12 First gas 13 Second gas 14 Quartz tube 15 Perforated diffuser 16 Light source 17 Reflector 18 Integrator 19 Light introduction window

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 H01L 21/31

Claims (9)

(57) [Claims] At least (1) a plasma processing chamber,
(2) means for evacuating the processing chamber to a vacuum, (3) means for supplying a processing gas into the processing chamber, (4) a plurality of slit holes are formed in the outer periphery of the processing chamber and formed inside. In a plasma processing apparatus having a plasma generating means having a microwave waveguide, and (5) a plasma processing apparatus having means for holding a substrate to be processed, microwave plasma processing comprising means for changing a guide wavelength of the microwave waveguide. apparatus. 2. The means for changing the guide wavelength of a waveguide comprises:
2. The microwave plasma processing apparatus according to claim 1, wherein the means changes a cross-sectional dimension of the waveguide. 3. The means for changing the guide wavelength of a waveguide comprises:
3. The microwave plasma processing apparatus according to claim 2, wherein the inner wall surface of the waveguide is movable. 4. The means for changing the guide wavelength of a waveguide comprises:
2. The microwave plasma processing apparatus according to claim 1, wherein the microwave plasma processing apparatus is means for changing an oscillation wavelength of the power supply. 5. The microwave plasma processing apparatus according to claim 1, wherein the substrate holding means is installed so as not to contact the high-density plasma portion. 6. A microwave plasma processing method using the microwave plasma processing apparatus according to claim 1. 7. The microwave plasma processing method according to claim 6, wherein the substrate holding means is irradiated with light including near-ultraviolet light. 8. H, O, N, F, Cl, Br, He, N
e, supplying a first gas containing only an element selected from Ar, Kr, Xe and Rn to the plasma generation space,
H, O, N, F, Cl, Br, He, Ne, Ar, K
The microwave plasma processing method according to claim 6 or 7, wherein a second gas containing an element other than r, Xe, and Rn is supplied to a space isolated from the plasma. 9. The microwave plasma processing method according to claim 8, wherein the first gas is O ₂ and the second gas is tetraethoxysilane.