KR101485140B1 - Plasma processing apparatus - Google Patents

Abstract

A cathode electrode having a through hole provided with an opening in a surface opposite to the anode electrode; a gas supply device for introducing a process gas between the anode electrode and the cathode electrode; and a gas supply device for supplying AC power between the anode electrode and the cathode electrode And an AC power source for bringing the process gas into a plasma state between the anode electrode and the cathode electrode.

Description

PLASMA PROCESSING APPARATUS

The present invention relates to a plasma processing apparatus for generating a plasma to perform a substrate processing.

A plasma processing apparatus is used in a film forming process, an etching process, an ashing process, and the like in view of the fact that process control of high precision is easy in a semiconductor device manufacturing process. As a plasma processing apparatus, for example, a plasma chemical vapor deposition (CVD) apparatus, a plasma etching apparatus, a plasma ashing apparatus, and the like are known. For example, in a plasma CVD apparatus, a raw material gas is plasmaized by high-frequency power or the like, and a thin film is formed on a substrate by a chemical reaction.

Further, a plasma processing apparatus using a shower electrode for supplying a process gas from the inside of the cathode electrode and a plasma processing apparatus using a hollow cathode discharge in the shower electrode for generating a higher density plasma have been proposed in order to make the plasma density uniform (See, for example, Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-296526

However, in order to perform the plasma treatment by the shower electrode, it is necessary to form a large number of fine holes having a diameter of about 0.3 to 0.4 mm on the surface of the cathode electrode. For this reason, the manufacture and maintenance of the cathode electrode are difficult and the cost is high. In addition, the shower electrode may be clogged so that continuous use may not be possible. This problem also occurs in a plasma processing apparatus using a hollow cathode discharge. In the cited example, plasma is generated on only one surface facing the cathode, and it is difficult to stably generate plasma having uniform and high density on both surfaces of the cathode electrode.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a plasma processing apparatus capable of stably generating a uniform and high-density plasma on both sides of a cathode electrode.

According to one aspect of the present invention, there is provided a plasma processing apparatus comprising: an anode electrode for mounting a processing substrate; a cathode electrode disposed opposite to the anode electrode and having a through hole provided with an opening in an opposing surface; There is provided a plasma processing apparatus comprising a gas supply device for introducing a plasma and an alternating current power supply for supplying AC power between the anode electrode and the cathode electrode to bring the process gas into a plasma state between the anode electrode and the cathode electrode.

According to the present invention, it is possible to provide a plasma processing apparatus capable of stably generating a uniform and high-density plasma on both surfaces of a cathode electrode.

1 is a schematic view showing a configuration of a plasma processing apparatus according to a first embodiment of the present invention.
2 is a schematic view for explaining a plasma region in a through hole of the plasma processing apparatus according to the first embodiment of the present invention (Part 1).
3 is a schematic view for explaining a plasma region in a through hole of the plasma processing apparatus according to the first embodiment of the present invention (Part 2).
4 is a schematic view for explaining a plasma region in a through hole of the plasma processing apparatus according to the first embodiment of the present invention (Part 3).
5 is a schematic view for explaining a plasma region in a through hole of the plasma processing apparatus according to the first embodiment of the present invention (Part 4).
6 is a schematic view for explaining the hollow cathode discharge of the comparative example.
7 is a schematic view showing an example of the structure of a cathode electrode of the plasma processing apparatus according to the first embodiment of the present invention.
8 is a schematic view showing an example of the arrangement of openings of through holes formed in the cathode electrode of the plasma processing apparatus according to the first embodiment of the present invention.
9 is a schematic diagram showing a discharge state in the plasma processing apparatus according to the first embodiment of the present invention.
10 is a schematic view showing another discharge state in the plasma processing apparatus according to the first embodiment of the present invention.
11 is a table showing conditions of a hollow cathode discharge in the plasma processing apparatus according to the first embodiment of the present invention.
12 is a graph showing the relationship between the mean free path of electrons and the pressure.
13 is a table showing an example of calculated values of the Debye length.
14 is a schematic view showing a configuration of a plasma processing apparatus according to a first modification of the first embodiment of the present invention.
15 is a schematic view showing a configuration of a plasma processing apparatus according to a second modification of the first embodiment of the present invention.
16 is a schematic view showing a configuration of a plasma processing apparatus according to a second embodiment of the present invention.
17 is a schematic diagram showing another configuration of the plasma processing apparatus according to the second embodiment of the present invention.
18 is a schematic diagram showing a configuration of a plasma processing apparatus according to a modified example of the second embodiment of the present invention.

Next, the first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. It should be noted, however, that the drawings are schematic. The first and second embodiments described below exemplify an apparatus and a method for embodying the technical idea of the present invention. The embodiment of the present invention specifies the structure, arrangement, and the like of the constituent parts as follows It is not. The embodiments of the present invention may be modified in various ways within the scope of the claims.

(First Embodiment)

1, the plasma processing apparatus 10 according to the first embodiment of the present invention includes an anode electrode 11 on which a processing substrate is mounted, a through-hole (not shown) having an opening on a surface facing the anode electrode 11, A cathode electrode 12 having an anode electrode 11 and a cathode electrode 12 and a gas supply device 13 for introducing the process gas 100 between the anode electrode 11 and the cathode electrode 12, And an AC power supply 14 for supplying AC power between the anode electrode 11 and the cathode electrode 12 to bring the process gas 100 into a plasma state. As shown in FIG. 1, the anode electrode 11 and the cathode electrode 12 are of a flat plate type, and the plasma processing apparatus 10 uses a capacitively coupled plasma. It is preferable that the distance between the electrodes of the capacitive coupling method is roughly uniform.

The cathode electrode 12 provided with an opening on its surface functions as a hollow cathode electrode for generating a hollow cathode discharge. Hereinafter, the hollow cathode discharge will be described.

In general capacitively coupled plasma, the ionization of gas molecules is chained to the ionization from the secondary electrons emitted by the incident ions to the surface of the cathode electrode 12 as a starting point. In the case of the present invention, this is the plasma generation on the surface of the cathode electrode 12 except for the inside of the through hole 120. On the other hand, plasma generation inside the through hole 120 is a hollow cathode discharge. In the hollow cathode discharge, electrons are confined in the through hole 120 in the through hole 120 of the cathode electrode 12, , A space of high-density electrons is formed. That is, due to the negative electrode drop generated in the side wall of the through hole 120 provided in the cathode electrode 12, the electrons are excited to disappear by being incident on the side wall of the through hole 120. That is, repulsion such as a so-called " pendulum effect " in which electrons are repelled from the opposite wall surface in the through hole 120 is repeated to form a high-density electron space inside the through hole 120. [ The electrons impinging on the gas molecules repeat the inelastic collision and maintain and promote ionization. These electrons are scattered in various directions within the through hole 120, and repeat ionization amplification and cumulative ionization.

The above phenomenon will be described with reference to Figs. 2 to 5. Fig. 2 is an enlarged view of the area A shown in Fig. A glow discharge region 101 is formed between the anode electrode 11 and the cathode electrode 12 and a hollow discharge region 102 is formed in the through hole 120 formed in the cathode electrode 12. A sheath region 200 is formed between the anode electrode 11 and the cathode electrode 12 and the glow discharge region 101, respectively. A sheath region 200 is formed between the cathode electrode 12 and the hollow discharge region 102 in the through hole 120. [ The distance between the anode electrode 11 and the cathode electrode 12 is a distance S.

3, the ions 50 entering the through hole 120 are accelerated by the sheath region 200 and collide with the inner wall surface of the cathode electrode 12.

The secondary electrons 60 emitted from the wall surface are accelerated in the direction perpendicular to the wall surface by the sheath electric field, as shown in Fig. The secondary electrons 60 accelerated to obtain sufficient energy collide with the neutral gas molecules 70 and cause electronic avalanche. As a result, the electron density inside the through hole 120 rapidly increases.

As shown in Fig. 5, among the secondary electrons 60 emitted from the wall surface, the electrons 61 reaching the vicinity of the wall surface on the opposite side are repelled by the opposite side sheath electric field and pushed back into the plasma. This is called a pendulum motion effect, and the probability of existence of electrons in the through hole 120 dramatically increases. By this action, the inside of the through hole 120 is maintained at a high electron density, and the plasma structure is different from the glow discharge formed between the parallel flat plates.

The gas molecules intruding into the high electron density region are repeatedly ionized and recombined, and observed as high-luminance light emission upon recombination. The precursor 80 generated in the high density plasma is a radical species and diffuses out of the through hole 120 regardless of the electrode potential and forms a thin film on the surface of the substrate disposed on the anode electrode 11, for example.

The diameter of the through hole 120 for obtaining a uniform high electron density is considered from the pressure, the temperature, the process gas species, and the mean free path of electrons. The diameter of the through hole 120 will be described later.

In addition, from the above-described principle, it is very suitable for the cathode electrode 12 to be a carbon material which is inexpensive, easy to process and easy to clean, such as cleaning. For example, the cathode electrode 12 made of a carbon material can be cleaned by hydrofluoric acid treatment. Further, by using the carbon material, deformation due to the high temperature in the plasma processing step does not occur. Alternatively, an aluminum alloy or the like in which a metal oxide film is easily formed is a material suitable for a hollow cathode electrode. In addition, carbon, stainless alloy, copper, copper alloy, glass, ceramics and the like containing carbon fiber can be used for the cathode electrode 12. Alternatively, the above-described material may be subjected to an alumite treatment, plating, or spray coating.

A carbon material is also suitably used for the anode electrode 11. In addition, carbon, an aluminum alloy, a stainless steel alloy, copper, a copper alloy, glass, ceramics, or the like containing carbon fibers can be used for the anode electrode 11. Alternatively, such material may be coated with an alumite treatment, plating, or spraying.

1, a plurality of through holes 120 in which a hollow cathode discharge is generated are formed at a constant density on the surface of the cathode electrode 12, An electron density electric field can be easily achieved. This is because the difference in the density of the plasma density on both sides of the cathode electrode 12 is automatically corrected by the nature of the bipolar diffusion of the plasma through the through hole 120.

On the contrary, a comparative example in which a concave portion 601 is formed on the surface of the cathode electrode 12A as shown in Fig. 6 and a gas jet port 602 is provided on the bottom of the concave portion 601 is examined. In this comparative example, a shower electrode to which the process gas 100 is supplied from the inside of the cathode electrode 12A is employed. In the comparative example shown in Fig. 6, the interior of the concave portion 601 is a space in which high-density plasma due to the hollow cathode discharge is generated. The process gas 100 is efficiently injected into the high-density plasma space by ejecting the process gas 100 from the gas injection port 602 having a very small diameter formed on the bottom surface of the concave portion 601.

6, it is difficult to uniformly supply the process gas 100 to a large number of recesses 601, and it is difficult to uniformly supply the process gas 100 to the recesses 601, And pressure. Further, since the gas jet port 602 has an extremely small diameter, clogging tends to occur. If the process gas 100 can not be introduced due to the clogging, the hollow cathode discharge is unlikely to occur in the concave portion 601 causing the clogging, so that the uniformity of the discharge at the front surface of the cathode electrode 12A can not be maintained .

On the other hand, in the plasma processing apparatus 10 shown in FIG. 1, a process gas flows stably near the through hole 120 where a high-density plasma is generated by a hollow cathode discharge. Therefore, the uniformity of the discharge is maintained at the respective front surfaces of both surfaces of the cathode electrode 12.

It is preferable that the through holes 120 are formed on the surface of the cathode electrode 12 as much as possible. For example, the through holes 120 are formed so that the openings are arranged most densely on the surface of the cathode electrode 12, such as the hexagonal close-packed arrangement. As a result, uniform high-density plasma is formed on the surface of the cathode electrode 12.

7 shows an example of the surface of the cathode electrode 12 having the opening of the through hole 120 formed therein. 8, when the diameter of the through hole 120 is 5 mm, the distance between the centers of the through holes 120 adjacent to each other in the up-and-down direction is set to 3 mm, The distance between the through holes 120 in the left-right direction is set to 5.2 mm.

7, the gas supply nozzle 130 for ejecting the process gas 100 of the gas supply device 13 is directed to the bottom surface of the cathode electrode 12, and a plurality of gas supply nozzles 130 The gas supply nozzle 130 is arranged along the bottom surface of the cathode electrode 12. In this case, The process gas 100 can be supplied substantially uniformly to both surfaces of the cathode electrode 12 by directing the gas supply nozzle 130 to the bottom surface of the cathode electrode 12. [

In the case where the process gas 100 is a gas obtained by mixing a plurality of kinds of gases, the process gas 100 in which all the gases are mixed may be supplied from the gas supply nozzle 130, Gas may be supplied from the gas supply source 130 respectively.

It is necessary to examine the behavior of electrons in order to determine the size of the through hole 120 for efficiently forming the hollow cathode discharge in the plasma processing apparatus 10 shown in Fig. The behavior of electrons in the through hole 120 will be described below.

Fig. 9 shows details of the discharge state in the region A in Fig. The electrons can not penetrate inwardly of the cathode electrode 12 beyond the deave length lambda d and repel. Further, the electrons emitted from the inner wall surface of the through hole 120 cause a first collision with the gas molecules near the average free path of electrons, and ionize the gas molecules to generate plasma. In Fig. 9, the distance "a" from both sides of the diameter d of the through hole 120, excluding the deck length λd, is represented by the length "a". If the mean free path of the electrons is b, then the following equation (1) holds:

a = 2b + c (1)

In Equation (1), the length c is the distance in the radial direction of the region excluding the sheath region inside the through hole 120. [ The diameter d of the through hole 120 is expressed by the following formula (2)

d = a + 2 占 d = 2b + c + 2 占 d (2)

When c = 0, a movement space of electrons having sufficient kinetic energy can not be secured, and sufficient plasma generation space can not be secured in the through hole 120.

10, when a diameter d of the through hole 120 is large as in c > 5b, a high density plasma is generated inside the through hole 120 so as to stick to the wall surface of the through hole 120 do. Therefore, in the center space of the through hole 120, which is represented by the length f, the plasma density becomes thin.

On the other hand, as shown in Fig. 11, as the diameter d of the through hole 120 becomes smaller, the electron moving range represented by the length c in the through hole 120 becomes smaller. For this reason, sufficient plasma space can not be generated.

11 is a table showing conditions under which the gaseous ammonia, the pressure P at which the hollow cathode discharge occurs at a temperature of 673 K, and the diameter d of the through hole 120 is d. 11, the ratio of the diameter d of the through hole 120 to the mean free path Y of electrons is 2.38, and the number of times of collision 3.7 is set as a condition for generating the hollow cathode discharge. As shown in Fig. 11, the smaller the diameter d of the through hole 120 becomes, the smaller the length c becomes, and it becomes difficult to secure the plasma generating space.

If the length c is optimum, a movement space of electrons having sufficient kinetic energy is ensured, and a high-density plasma space of sufficient width is secured.

Fig. 12 shows the relationship between the mean free path Y of electrons and the pressure P when the temperature is 673K. In Fig. 12, the circle mark indicates an average free stroke in ammonia (NH ₃ ) gas, and the triangular mark indicates an average free stroke in monosilane (SiH ₄ ) gas. The mean free stroke Y at the pressures P = 67, 87, and 130 Pa shown in Fig. 11 is represented by a decolored circle display and a triangular display in Fig.

Further, the relationship between the debye length lambda d, the electron temperature Te, and the electron density ne is expressed by the following formula (3): < EMI ID =

? d = 7.4 × 10 ³ × (Te / ne) ^1/2 (3)

Fig. 13 shows an example of a calculated value of the debue length lambda d. In this case, the electron density and the electron temperature of a general high-density glow discharge plasma were used to calculate a debub length lambda d. The average free path lambda g of the gas molecules is represented by equation (4) and the mean free path lambda e of electrons is represented by equation (5), respectively:

^{λg = 3.11 × 10 -24 × T} 4 / (P × D) and and and (4)

? e =? g x 4 x 2 ^1/2 (5)

In the equation (4), T is the atmospheric temperature (K), P is the pressure (Pa), and D is the diameter (m) of the gas molecules.

By setting the optimal length c as described above, the diameter d of the through hole 120 can be determined. That is, it is possible to prepare the cathode electrode 12 specially designed to generate the hollow cathode discharge most efficiently by the predetermined pressure, the ambient temperature, and the gas species.

In the plasma processing apparatus 10 shown in Fig. 1, it is necessary to generate a hollow cathode discharge by using the effect of the pendulum motion of electrons most efficiently in the through hole 120. Fig. At this time, the mean free path of electrons is determined by the atmospheric temperature, the pressure, and the size of the gas molecules. The inventors of the present invention conducted an experiment using a mixed gas of monosilane (SiH ₄ ) gas and ammonia (NH ₃ ) gas as the process gas 100 by using the cathode electrode 12 having a plurality of through holes 120 . The diameter of the through hole 120 is 5.0 mm and the thickness of the cathode electrode 12, that is, the length t of the through hole 120 is set to be 5.0 mm when the atmospheric temperature T is set to 350 ° C to 450 ° C and the pressure P is set to 67 Pa 5 mm and a distance S between the anode electrode 11 and the cathode electrode 12 was 16 mm, a uniform multi-hollow discharge could be obtained on both sides of the cathode electrode 12. The term " multi-hollow discharge " refers to a discharge generated on the surface of the cathode electrode 12 by combining the hollow cathode discharge formed in each of the through holes 120.

Further, when the diameter of the through hole 120 was 3.9 mm and 2.9 mm, a uniform multi-hollow discharge was obtained at a pressure P of approximately 87 Pa and 130 Pa, respectively, as shown in Fig. This is 4.72 times the mean free path of electrons in the monosilane gas and 2.38 times the mean free path of electrons in the ammonia gas when the ambient temperature T is 400 DEG C (the mean free path of electrons in the monosilane gas and the electron The ratio of the mean free path of 1.98).

In practice, since the mixed gas is used as the process gas 100, the diameter d of the through hole 120 is calculated based on the average free stroke of electrons in the ammonia gas having a large gas flow rate ratio. Specifically, when a mixed gas of monosilane gas and ammonia gas is used and the diameter d of the through hole 120 is 5 mm when the ambient temperature T is 400 ° C and the pressure P is 67 Pa, Uniform multi-hollow discharge is obtained on both sides of the discharge space. The CVD process gas is usually mixed with gas species such as monosilane, hydrogen, and nitrogen. However, in consideration of the diameter of the through hole 120, attention is focused on the gas species having the longest average free stroke in the mixed gas, Lt; / RTI > diameter.

Further, in order to obtain easy processing and a multi-hollow discharge at a desired pressure, it is preferable that the diameter d of the through hole 120 is set to about 3.8 mm to 8.0 mm. These dimensions are easier than forming the holes of 0.3 mm to 0.4 mm necessary for manufacturing shower electrodes. Therefore, the manufacturing cost of the plasma processing apparatus 10 can be reduced.

In the above example, the cross section of the through hole 120 is circular. However, the cross-section of the through hole 120 may be a polygon having a rough diameter of about 3.8 mm to 8.0 mm.

A plurality of through holes 120 having the same cross sectional shape along the major axis direction may be formed in the cathode electrode 12 or a plurality of through holes 120 having different cross- May be formed in a mixed manner. By mixing the through holes 120 having different diameters d, a multi-hollow discharge can be obtained under a plurality of conditions in which pressure, temperature, gas species, and the like are different.

The length of the through hole 120 in the long axis direction, that is, the thickness t of the cathode electrode 12 is set to about 3 mm to 10 mm, preferably about 5 mm, so that a hollow cathode discharge easily occurs.

The distance S between the anode electrode 11 and the cathode electrode 12 is preferably about 10 mm to 40 mm. As a result, plasma can be uniformly generated between the anode electrode 11 and the cathode electrode 12.

In the conventional method such as the comparative example shown in Fig. 6, starting from the uniform discharge of the process gas 100 like a shower from the concave portion 601 in which the high-density plasma is generated by the hollow cathode discharge, The uniformity of the plasma can be obtained at the front surface of the plasma display panel.

On the other hand, in the plasma processing apparatus 10 shown in FIG. 1, the process gas 100 is introduced without passing through the cathode electrode 12. Since the diameter d of the through hole 120 is considerably larger than the diameter of the hole required for the shower electrode, there is no fear of clogging and maintenance is also easy.

The plasma processing apparatus 10 preferably introduces the process gas 100 between the anode electrode 11 and the cathode electrode 12 from the lower side toward the upper side. By introducing the process gas 100 from below, the gas molecules and the radical particles, which are made into plasma with a small specific gravity, naturally flow over the surface of the cathode electrode 12 as an upward flow. Therefore, the process gas is uniformly supplied to the surface of the cathode electrode 12 without using a complicated structure such as a shower electrode. Since the space through which the high-density plasma is generated by the hollow cathode discharge is the through-hole 120, the continuity of the plasma is ensured inside and outside the cathode electrode 12, and the density of the plasma density is compensated automatically do. Therefore, in the plasma processing apparatus 10, uniform high-density plasma can be generated on both surfaces of the cathode electrode 12.

It is preferable that the surface of the cathode electrode 12 is smooth so that the process gas 100 flows smoothly and the surface roughness is finished to 3 탆 or less except for the inner surface of the through hole 120. For example, the surface of the cathode electrode 12 is flattened so that the finish symbol is represented by " < " > That is, it is preferable that the maximum height Ry is 6.3 S, the 10-point average roughness Rz is 6.3 Z, and the arithmetic mean roughness Ra is less than 1.6 a. By decreasing the surface roughness of the cathode electrode 12, the deposition rate of the thin film formed on the substrate 1 can be increased.

As described above, according to the plasma processing apparatus 10 of the first embodiment of the present invention, the through holes 120 are formed in the cathode electrode 12, It is possible to stably generate plasma. The manufacturing period of the plasma processing apparatus 10 is short and the production yield is improved as compared with an apparatus using a shower electrode requiring processing of several thousand or more fine holes. Therefore, an increase in the manufacturing cost of the plasma processing apparatus 10 is suppressed.

Further, according to the plasma processing apparatus 10, it is possible to generate a high-density plasma uniformly in a large area irrespective of the frequency of the alternating-current power supplied from the alternating-current power supply 14. Uniform and high-density plasma can be generated even when the frequency of the alternating-current power supplied by the alternating-current power supply 14 is set to, for example, about 60 Hz to 27 MHz. In other words, there is no need to use an AC power supply for supplying AC power in the expensive VHF band. On the other hand, in the conventional parallel plate type plasma processing apparatus, in order to perform high-density capacitive coupling high-frequency discharge in a large area, for example, instead of the frequency of 13.56 MHz in the RF band, In order to solve the unevenness of the plasma density, it was necessary to use the frequency of the VHF band such as 27 MHz or more of 13.56 MHz or more.

In the plasma processing apparatus 10, even inexpensive low frequency RF band such as 250 KHz, it is possible to obtain a high density plasma equal to or higher than that of the conventional plasma processing apparatus using the AC power of the VHF band.

The AC power output from the AC power supply 14 may be supplied between the anode electrode 11 and the cathode electrode 12 through the pulse generator. For example, the output of the pulse generator is supplied to the cathode electrode 12, and the anode electrode 11 is grounded. The plasma is stably formed by stopping the supply of the AC power at a constant cycle. This is because the temperature of the electrons is lowered and the stability of discharge is improved by providing a stop period for supplying AC power.

For example, the anode electrode 11 and the cathode electrode 11 may be alternately arranged such that the on-time for supplying AC power is 600 microseconds and the off-time for stopping the supply of AC power is 50 microseconds, 12 are supplied with AC power. It is preferable that the on-time is set in the range of about 100 μsec to 1000 μsec, and the off-time is set in the range of about 10 μsec to 100 μsec.

As described above, the supply of the AC power between the anode electrode 11 and the cathode electrode 12 is pulse-controlled, and the supply of the AC power is periodically turned on and off, thereby suppressing the generation of the abnormal discharge.

<First Modification>

Fig. 14 shows an example of the plasma processing apparatus 10 in the case where one anode electrode 11 is provided. 14, when the plasma is excited to only one surface of the cathode electrode 12, the cathode back plate 121 is formed at a position of distance k from the surface of the cathode electrode 12 not exciting the plasma, . At this time, the distance k is set so that k < b (b: electron mean free path) so that no plasma is generated between the cathode electrode 12 and the cathode back plate 121. At this time, AC power is supplied from the AC power source 14 to the cathode electrode 12 and the cathode back plate 121. The process gas 100 is introduced between the anode electrode 11 and the cathode electrode 12 and between the cathode electrode 12 and the cathode back plate 121. [

&Lt; Second Modified Example &

An example in which the plasma processing apparatus 10 has a plurality of cathode electrodes 12 is shown in Fig. In the plasma processing apparatus 10 shown in FIG. 15, the cathode electrodes 12 are alternately arranged as the anode electrodes 11, while the anode electrodes 11 are disposed as the outermost ones. Therefore, the number of the anode electrodes 11 is one more than that of the cathode electrodes 12. Although FIG. 15 shows an example in which the number of the cathode electrodes 12 is three, it goes without saying that the number of the cathode electrodes 12 is not limited to three.

15, the number of plasma regions formed in the anode electrode 11 and the cathode electrode 12 can be increased. As a result, the processing capability of the plasma processing apparatus 10 is improved.

(Second Embodiment)

The plasma processing apparatus 10 shown in FIG. 1 can be applied to a plasma chemical vapor deposition (CVD) apparatus, a plasma etching apparatus, a plasma ashing apparatus, and the like.

16 shows an example in which the plasma processing apparatus 10 shown in Fig. 1 is used in a plasma CVD apparatus. The anode electrode 11 and the cathode electrode 12 are disposed in the chamber 20 and the substrate 1 to be film-formed is disposed on the anode electrode 11. The anode electrode 11 is grounded.

A gas containing a raw material gas for film formation is used as the process gas 100 and the process gas 100 is introduced into the chamber 20 from the gas supply device 13 through the gas supply nozzle 130.

The pressure in the chamber 20 is measured by a pressure gauge 16 such as a capacitance gauge and is an exhaust pump for evacuating the chamber 20 and is controlled by an exhaust speed control unit (APC) 20 are adjusted. The predetermined AC power is supplied between the cathode electrode 12 and the anode electrode 11 by the AC power source 14 after the pressure of the process gas 100 in the chamber 20 is adjusted to the predetermined gas pressure. This causes the process gas 100 in the chamber 20 to be plasmaized. A desired thin film mainly composed of the raw material contained in the source gas is formed on the exposed surface of the substrate 1 by squeezing the substrate 1 into the formed plasma.

The temperature of the substrate 1 during film formation may be set by the substrate heating heater 21 shown in Fig. By setting the temperature of the substrate 1 during film formation to a predetermined temperature, it is possible to increase the film formation speed and improve the film quality.

As described above, in the plasma processing apparatus 10 shown in Fig. 1, uniform high-density plasma is generated on the surface of the cathode electrode 12. Fig. For this reason, according to the plasma CVD apparatus shown in Fig. 16, the raw material gas is efficiently decomposed, and a thin film is uniformly formed on the substrate 1 at a high speed and with a large area. Therefore, the uniformity of film thickness and film quality of the film to be formed is improved, and the film forming speed is improved.

A desired thin film can be formed by appropriately selecting the source gas by the plasma CVD apparatus employing the plasma processing apparatus 10. [ For example, a silicon semiconductor thin film, a silicon nitride thin film, a silicon oxide thin film, a silicon oxynitride thin film, a carbon thin film, or the like can be formed on the substrate 1. Specifically, a silicon nitride (SiN) film is formed on the substrate 1 by using a mixed gas of ammonia (NH ₃ ) gas and monosilane (SiH ₄ ) gas. Alternatively, a silicon oxide (SiO _x ) film is formed on the substrate 1 by using a mixed gas of monosilane (SiH ₄ ) gas and N ₂ O gas, or using TEOS gas and oxygen gas.

17 shows an example in which an AC power source 17 is mounted on the anode electrode 11 separately from the AC power source 14 mounted on the cathode electrode 12. [ By supplying AC power to the anode electrode 11, the film quality of the thin film formed on the substrate 1 can be improved. The frequency of the alternating-current power supplied by the alternating-current power supply 17 may be equal to or lower than the frequency of the alternating-current power supplied by the alternating-current power supply 14. For example, the frequency of the alternating-current power supplied by the alternating-current power supply 17 is set to about 60 Hz to 27 MHz.

The anode electrode 11 can be cleaned by supplying AC power only from the AC power supply 17 without supplying AC power from the AC power supply 14. Specifically, the gas for sputtering is introduced into the chamber 20, and the anode electrode 11 is cleaned by sputter etching while AC power is supplied from the AC power source 17.

14 in which the cathode electrodes 12 and the anode electrodes 11 are respectively provided with the AC power sources 14 and 17 in the case of one anode electrode 11 as shown in Fig. 10) may be used for the plasma CVD apparatus. Further, as described above, the distance k from the surface of the cathode electrode 12 that does not excite the plasma to the cathode plate 121 is set so that k < b.

Further, by applying the plasma processing apparatus 10 having a plurality of cathode electrodes 12 as shown in Fig. 15 to a plasma CVD apparatus, the number of substrates to be formed at one time increases, and the film forming ability can be improved .

An example in which the plasma processing apparatus 10 shown in Fig. 1 is applied to a plasma CVD apparatus has been described above. The plasma processing apparatus 10 shown in Fig. 1 can be applied to a plasma etching apparatus, a plasma ashing apparatus or the like by replacing the gas species of the process gas 100 with the configuration shown in Fig. 15 or Fig.

For example, by introducing a plasma etching gas into the chamber 20 as the process gas 100, a plasma etching apparatus for etching off a film formed on the substrate 1 can be realized. The plasma etching gas is appropriately selected depending on the material to be etched. For example, a fluorine-based gas such as nitrogen trifluoride (NF ₃ ) gas or carbon tetrafluoride (CF ₄ ) gas can be employed.

In addition, by introducing the plasma ashing gas into the chamber 20 as the process gas 100, the plasma ashing apparatus using the plasma processing apparatus 10 can be realized. For example, by using oxygen and argon gas as the process gas 100, a carbon film, a photoresist film, or the like formed on the substrate 1 as an etching mask can be ashed.

As described above, by using the plasma processing apparatus 10 capable of stably generating a uniform and high-density plasma on both surfaces of the cathode electrode 12, the plasma processing apparatus 10, the plasma etching apparatus, the plasma ashing apparatus, Speed and precision can be improved.

As described above, the present invention has been described with reference to the first and second embodiments, but the description and the drawings constituting a part of this disclosure are not to be construed as limiting the present invention. Various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art from this disclosure. In other words, it goes without saying that the present invention includes various embodiments not described here. Accordingly, the technical scope of the present invention should be determined only by the inventive subject matter in accordance with the scope of the appended claims from the above description.

Industrial availability

The plasma processing apparatus of the present invention can be used for generating a uniform and high-density plasma on both sides of a cathode electrode.

Claims (13)

An anode electrode for mounting a substrate,
A cathode electrode disposed so as to face the anode electrode and having a through hole provided with an opening in an opposite surface,
A gas supply device for introducing a process gas between the anode electrode and the cathode electrode,
And an AC power supply for supplying AC power between the anode electrode and the cathode electrode to bring the process gas into a plasma state between the anode electrode and the cathode electrode,
Wherein the anode electrode is disposed opposite to both sides of the cathode electrode where the opening is provided. The method according to claim 1,
Wherein the gas supply device introduces the process gas between the anode electrode and the cathode electrode from the lower side toward the upper side. The method of claim 2,
Wherein the gas supply device sprays the process gas from a gas supply nozzle disposed along the bottom surface of the cathode toward the bottom of the cathode electrode. delete The method according to claim 1,
And a plurality of the cathode electrodes are provided. The method according to claim 1,
Wherein at least one of the anode electrode and the cathode electrode is made of carbon. The method according to claim 1,
And the diameter of the through hole is 3.8 mm or more and 8.0 mm or less. The method according to claim 1,
Wherein the openings are arranged on the surface of the cathode electrode in a hexagonal close-packed arrangement. The method according to claim 1,
Wherein the cathode electrode is formed with a plurality of kinds of through holes different in size or shape from each other in sectional shape along the major axis direction. The method according to claim 1,
Wherein the frequency of the AC power supplied by the AC power supply is 60 Hz or more and 27 MHz or less. The method according to claim 1,
Wherein a film containing a raw material contained in the source gas is formed on a substrate disposed on the anode electrode by using a gas containing a source gas for film formation as the process gas. The method according to claim 1,
Wherein a gas for etching a film formed on a surface of the substrate disposed on the anode electrode is used as the process gas. The method according to claim 1,
Wherein a gas containing oxygen gas and argon gas is used as the process gas to ashing the film formed on the surface of the substrate disposed on the anode electrode.

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