JP2662219B2 - Plasma processing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of semiconductor devices using low-temperature plasma, and more particularly to a plasma processing apparatus suitable for high-speed and uniform processing in various technologies such as CVD and etching. . [Prior art] An apparatus using low-temperature plasma is roughly classified into an apparatus using a technique of generating a plasma by applying a high frequency voltage of about 10 KHz to 30 MHz to one of parallel plate electrodes in a vacuum (Semiconductor Research) 18; P121-P170 Semiconductor Research 19; P225-P267),
Some use a technique of generating microwaves by introducing 2.45 GHz microwaves into a vacuum chamber. Conventionally, the technique using parallel plate electrodes has been mainly used among them. On the other hand, with the miniaturization of semiconductor elements, there has been a problem that element characteristics are affected by the impact of ions generated during plasma processing. Further, it is required to increase the processing speed in order to improve the processing capacity. When increasing the processing speed, simply increasing the density of plasma or the concentration of radicals (active particles immediately before ionization) is not sufficient. In dry etching by plasma processing and plasma CVD, ion energy plays an important role. In the case of dry etching, if the energy of ions is too large, the underlying film is scraped or affects the crystal structure, and the device characteristics are degraded. On the other hand, if it is too small, the polymer formed on the etching surface will not be sufficiently removed, and the etching speed will decrease. On the other hand, a problem occurs when a protective film made of a polymer is not formed, the side surfaces of the pattern are etched, and the dimensional accuracy of the pattern is deteriorated. Even in plasma CVD, if the energy of the ions is low, the composition becomes coarse, and if the energy is high, the ion energy affects the film formation such that the composition becomes dense. Therefore, increasing the density of the plasma and properly controlling the ion energy are indispensable for future plasma processing. As known examples, JP-A-56-13480 and JP-A-56-9684
A system using a microwave as shown in 1 has been proposed. When plasma is generated by microwaves, even if microwaves generated by the magnetron are radiated to the plasma generation chamber at low pressure, sufficient energy is not supplied to the electrons due to insufficient electric field strength of the microwaves, generating plasma. It is difficult to do that. Therefore, in order to generate plasma by microwaves, there is a method of matching the frequency of the microwave with the cyclotron frequency at which the electrons rotate on a plane perpendicular to the magnetic field and supplying energy to the electrons in a resonance state, There are two methods of irradiating the cavity resonator to increase the amplitude of the microwave and increasing the electric field strength to supply energy to electrons. The former is JP-A-56
As shown in -13480, magnetic field microwave or electron cyclotron resonance (Electron Cyc
This is called the lotron resonance (ECR) method. The latter is disclosed in JP-A-56-96841. In plasma generated by microwaves, the energy between sheaths formed between the plasma and the substrate hardly changes because energy is directly supplied to electrons from the microwaves. Therefore, by applying a high-frequency voltage to the electrode on which the substrate is mounted and arbitrarily controlling the voltage between the sheaths, it is possible to control the plasma density and the appropriate ion energy required for high-speed operation. In an apparatus using plasma generated by these microwaves, it is necessary to supply gas from a position that does not obstruct a path through which the microwave is introduced toward the substrate. Therefore, a single pipe outlet or a ring-shaped outlet is used. [Problems to be Solved by the Invention] As described above, ion energy plays an important role in plasma processing. However, in the conventional technology, the ECR method is disclosed in
As shown in 6-13480, when a high-frequency voltage is applied to the electrode on which the substrate is mounted, a high-frequency current flows between the electrode and the surrounding processing chamber because there is no ground electrode on the side facing this electrode. There is a problem that the effect of ion energy on the substrate is strong around the substrate and weak at the center, so that the entire substrate cannot be processed under uniform conditions. Also, in the method using a cavity resonator, plasma is generated in the resonator. Therefore, when plasma is generated, the wavelength of the microwave changes due to the density of the plasma, and the resonance conditions are not satisfied and the plasma is not generated. There was a problem of becoming stable. That is, since the resonance condition is satisfied until the plasma is generated, the electric field strength of the microwave is increased and the plasma is generated. However, when this plasma is generated and the plasma density is increased, the wavelength of the microwave changes and the resonance condition is no longer satisfied, and the electric field intensity decreases. Then, the supply of energy to the electrons decreases, and the plasma density decreases. When the plasma density decreases, the resonance condition is satisfied, and the plasma density increases again. Due to such a phenomenon, it has been difficult to generate plasma stably. Furthermore, if a high-frequency voltage application electrode is provided in the cavity resonator to control the energy of ions incident on these plasma substrates, the problem that the microwaves are reflected and the plasma becomes more unstable will occur. Atsuta. Regarding the gas supply method, the above-described gas supply method using a single-tube outlet or a ring-shaped outlet is used under a condition of a low pressure region of 10 mTorr or less or a condition where a gas supply flow rate is extremely small. This is because, under such conditions, the gas flow becomes a diffusion flow, and the gas concentration does not become uneven near the substrate, so that the substrate can be uniformly processed. However, when processing is performed in a pressure range of 10 mTorr or more as in the above-described conventional technology and when a gas with a large flow rate of 500 Scm ³ / sec or more is supplied, the flow becomes a viscous flow. There was a problem that the substrate could not be uniformly processed. SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus which solves the above-mentioned various problems in the prior art and enables high-speed and uniform processing. [Means for Solving the Problems] In order to achieve the above object, a microwave generating means, a microwave transporting means for transporting the microwave generated by the microwave generating means, and an inside evacuated to vacuum Processing chamber means for mounting a processing substrate, and a microwave introduction means as a cavity resonator for introducing the microwave into the processing chamber means, between the processing chamber means and the microwave transport means;
Between the microwave introducing means and the processing chamber means, a member capable of sealing the microwave introducing means in a vacuum and transmitting microwaves and a slit plate provided with a plurality of slits for radiating the microwaves to the processing chamber means. Stacking means provided in a stack,
Gas supply means provided at a position different from the slit in the slit plate of the stacking means with a gas flow passage for introducing gas as a shower-like gas into the processing chamber means. . [Operation] In the conventional ECR system, a microwave is directly radiated from the opening of the waveguide to the plasma generation chamber. Therefore, if an earth electrode is provided between the plasma generation chamber and the opening of the waveguide, the microwave is reflected by the earth electrode and cannot be supplied to the plasma generation chamber. Therefore, in the present invention, as described above, the microwave introducing means having the microwave generating means, the microwave transporting means, the processing chamber means, the microwave introducing means, the stacking means, and the gas supplying means is provided. Since the microwave transported between the processing chamber means and the microwave transport means and transported by the microwave transport means is introduced into the processing chamber means via the stacking means, the processing substrate of the processing chamber means is placed. When a high frequency is applied to the electrode, the high-frequency current flows evenly in the vacuum-sealed processing chamber means, and an ion effect can be generated uniformly over the entire surface of the processing substrate. Further, in the present invention, the stacking means stacks the member capable of transmitting microwaves by sealing the microwave introducing means in a vacuum and a slit plate provided with a plurality of slits for emitting microwaves to the processing chamber means. As a result, a sufficient amount of microwaves can be supplied to the processing chamber means through the slit, so that high-density plasma can be generated in the processing chamber means and the entire surface of the processing substrate can be generated. On the other hand, ion energy can be incident. On the other hand, when a gas is supplied into the slit, dense plasma is generated in the slit having a strong electric field, and energy is consumed there, so that the plasma density near the processing substrate may be reduced. In the present invention, as described above, the gas supply means is provided with a gas flow passage for guiding the gas as a shower-like gas into the processing chamber means at a position different from the slit in the slit plate of the stacking means. Because the path guides the shower-like gas into the processing chamber means, the microwave introduction path is not obstructed, and the possibility that the plasma density near the processing substrate is reduced can be eliminated. Thus, the gas flows uniformly over the entire surface of the processing substrate. As a result, uniform film formation can be performed at high speed. Embodiments Hereinafter, FIGS. 1 to 8 showing embodiments of the present invention will be described. As shown in FIG. 1, the cavity resonator 1 is formed in a circular cavity resonator of E ₀₁ mode, the microwave is supplied from the magnetron 3 through the waveguide 2. The waveguide 2 is E
_In order to improve the coupling with the ₀₁ mode, it is mounted eccentrically with respect to the circular cavity resonator 1. On the other side of the circular cavity resonator 1, a ceramic plate 4 and a slit plate 5 are fixed. A plasma generation chamber 6 is connected below the chamber. The ceramics 4 is provided to seal the inside of the circular cavity resonator 1 in a vacuum. The slit plate 5 is formed in a flat plate shape, as shown in FIGS. 2 and 3, with respect to the electric field E ₀₁ mode, with an opening at plurality of ring-shaped slit 5c is formed in a direction perpendicular I have. When a microwave of 2.45 GHz is used, each slit 5c is formed to have a length of 60 mm or more corresponding to a half wavelength of the microwave in order to improve the radiation of the microwave from the slit 5c. . The plasma generation chamber 6 (FIG. 1) is provided with an electrode 7, a gas supply pipe 9, and a gas exhaust pipe 10. The electrode 7
Is fixed in the plasma generation chamber 6 via an insulating material 8 and is connected to a high-frequency power supply 11. The gas supply 9 is connected to a gas supply source (not shown) so as to supply a plasma processing gas at a preset flow rate from the gas supply source. The slit plate 5 has concentric grooves 5d between the plurality of slits 5c and a number of small holes 5e opening from the grooves 5d toward the inside of the plasma generation chamber 6.
Therefore, as is apparent from FIG.
When the ceramics plate 4 and the ceramics plate 4 are closely contacted and stacked, the groove 5 d is formed between the slit bun 5 and the ceramics plate 4.
And the small hole 5e, a gas flow passage connecting the gas supply pipe 9 and the inside of the plasma generation chamber 6 is formed, and the gas from the gas supply pipe 9 is supplied to the inside of the plasma generation chamber 6 by the gas flow passage. It is jetted onto a shower toward a substrate 12 placed on the electrode 7. The gas exhaust pipe 10 is connected to a vacuum exhaust pump (not shown) to control the inside of the plasma generation chamber 6 to a pressure of 1 to 10 ^-3 Torr. Since the plasma processing apparatus according to the present invention is configured as described above, next, etching and plasma CVD are performed.
Will be described. When the magnetron 3 is operated and a microwave is oscillated and supplied to the cavity resonator 1 by the waveguide 2, the energy of the microwave whose amplitude is increased in the cavity resonator 1 is transmitted to the slit 5 of the slit plate 5. It is radiated to the plasma generation chamber 6 from 5c. Since the amplitude of the microwave radiated into the plasma generation chamber 6 is increased in the cavity resonator 1, even if the plasma generation chamber 6 is not configured as a cavity resonator, plasma is generated. Lit and maintained. Next, the case of etching in this state will be described. An etching gas is supplied from the gas supply pipe 9, exhausted from the gas exhaust pipe 10, and a microwave is supplied into the generation chamber 6 with the plasma at a constant gas pressure to thereby allow the slit plate 5 and the electrode 7 to communicate with each other. When the plasma is generated by the microwave during the period, the microwave acts directly on the electrons in the plasma, and the potential difference between the plasma and the electrode 7 is at a level of 20 to 30 V. Thereafter, a wafer 12 to be processed is placed on the electrode 7, and a high-frequency voltage is applied to the electrode 7 from a high-frequency power supply 11. The electrode 7 and the slit plate 5 are installed in parallel with each other, and the high-frequency current flows evenly on the electrode 7 and the slit plate 5, so that a high-frequency current is generated between the electrode 7 and the plasma. The electric field generated is uniform and the wafer 12
The ions of the etching gas having uniform energy are controlled by the application of a high-frequency voltage and are incident on the entire surface of the substrate. Active species (radicals) of the etching gas excited in the plasma or ions of the etching gas and the wafer
Etching proceeds as the film to be processed on 12 reacts. At this time, since the energy of the incident ions is uniform and the gas flow is also uniform, uniform etching can be performed on the entire surface of the wafer 12. Next, plasma CVD will be described. A gas mixture of SiH ₄ and N ₂ , N ₂ O is supplied from the gas supply pipe 9, N ₂ O, SiH ₄ is decomposed by plasma to generate SiO, and a film is formed on the wafer 12. In addition, the wafer 12
The film quality of the above film formation is controlled. At this time, since the incident energy of ions is uniform and the gas flow is also uniform, a uniform film is formed on the entire surface of the wafer 12. In the above embodiment, although a case microwave mode of the circular waveguide is E ₀₁ mode, but is not limited thereto. However, when the slit is in a direction perpendicular to the current flowing on the surface of the cavity, the efficiency of microwave radiation is better. In the case of the _H01 mode, the slit is radiated radially as shown in FIG. 5c ′
In the case of the _H01 mode, a slit 5c "is formed so that the center is straight and both sides are curved inward. Also, when the shape of the slits 5c 'and 5c" is changed as described above, It is clear from the description of FIGS. 2 and 3 that the shape of the groove forming the gas flow path needs to be formed so as to avoid the slits 5c 'and 5c ". 6 to 8 showing another embodiment of the present invention.
The figure will be described. 6 and 7, the ceramic plate 4 '
And a slit plate 5 'and a gas blow-out plate 5f in a San-Germanic manner. In this case, the gas blow-out plate 5f is formed of, for example, alumina ceramic and quartz which can transmit microwaves. In FIG. 6,
A gas passage 5d 'and a hole 5e' are formed in the gas blow-out plate 5f. In FIG. 7, a slit plate 5 'and a gas passage 5d' are formed. Next, in FIG. 8, the slit 5c is formed in a tapered shape in order to increase the amount of microwave radiation. The ceramics plates 4 'and 4 "are not limited to ceramics, but may be made of any material that can transmit microwaves. Therefore, the plasma processing apparatus according to the present invention uses a plasma using microwaves. The electrode can be provided on the surface facing the electrode for processing the wafer, and a uniform gas can be supplied onto the substrate in the form of a shower, so that uniform plasma processing can be performed, and Since the plasma generation chamber does not need to be configured as a cavity resonator, the configuration of the electrodes and the plasma generation chamber is not restricted [Effects of the Invention] According to the present invention, generation of plasma using microwaves is stabilized. In addition, since there is no restriction on the device configuration due to the relationship with the cavity resonator, connecting the cavity resonator to the earth potential can be applied to the electrode on which the processing target is placed. A parallel counter electrode can be configured, and as a result, microwave energy can be propagated through a slit provided on the counter electrode, and a uniform amount of gas can be supplied to the substrate. The effects of the generated ions and radicals can be uniformly applied to the object to be processed, and the effects of the ions and radicals can be generated uniformly, resulting in high-speed plasma processing with optimal ion energy. According to the present invention, a fine pattern on a semiconductor wafer can be formed with high accuracy, at high speed and with low damage, and uniform film formation can be performed at high speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a plasma processing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of a slit plate shown in FIG. 1, and FIG. AA 'sectional view, FIG. 4 and FIG.
The drawings are plan views showing another embodiment of the slit plate, and FIGS. 6 to 8 are cross-sectional views showing another embodiment of the gas outlet. 1 ... cavity resonator, 2 ... waveguide, 3 ... magnetron, 4, 4 ', 4 "... ceramic plate, 5, 5', 5" ... slit plate, 5c, 5c ', 5c ″, 5c …… Slits, 5e, 5e ′, 5
e "... Small hole, 6 ... Plasma generation chamber, 7 ... Electrode, 8
... insulating material, 9 ... gas supply pipe, 10 ... gas discharge pipe.

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References JP-A-62-31112 (JP, A)                 JP-A-61-222131 (JP, A)                 JP-A-62-58631 (JP, A)

Claims (1)

(57) [Claims] Microwave generating means, and microwave transport means for transporting the microwave generated by the microwave generating means,
A processing chamber means for placing a processing substrate inside a vacuum evacuated chamber, and microwave introduction as a cavity resonator between the processing chamber means and the microwave transport means for introducing the microwave into the treatment chamber means. Means, between the microwave introduction means and the processing chamber means, a slit which seals the microwave introduction means in a vacuum and has a member capable of transmitting microwaves and a plurality of slits for emitting microwaves to the processing chamber means A stacking means provided by stacking plates and a gas flow passage provided at a position different from the slit in the slit plate of the stacking means, for introducing a gas as a shower-like gas into the processing chamber means. A plasma processing apparatus comprising: a supply unit.