JPH0331480A - Plasma treating device by microwave - Google Patents

Abstract

PURPOSE:To enhance operating efficiency and to always stabilize plasma treatment by constituting a microwave electric power supplying means of a coaxial line which consists of a central conductor inserted into a closed vessel, a microwave transmissive member and an electrically-conductive member. CONSTITUTION:A microwave electric power supplying means is constituted of a central conductor 104 inserted into a closed vessel 108, a microwave transmissive member 107 having a rotary symmetrical shape and an electrically- conductive member 109 having the rotary symmetrical shape. Microwave is transmitted to the central conductor 104, an external conductor 105 and the connection part of a square waveguide 102 via this square waveguide 102. The inserted lengths of a coaxial short plunger 106, a square short plunger 103 and the central conductor 104 adjusted and plenty of microwave electric power is accumulated in a semi-coaxial resonator. Microwave electric field intensity is obtained which is sufficient to plasmaize a gaseous raw material in the semi- coaxial resonator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a microwave plasma processing apparatus having a novel microwave power supply means. More specifically, the present invention relates to a microwave plasma processing apparatus particularly suitable for plasma processing of large-area substrates.

[Description of prior art]

Plasma treatment is a process in which energy such as electromagnetic waves is applied to a specific substance to turn it into plasma, creating highly active radicals, which are then brought into contact with a substrate to form a deposited film on the substrate. It refers to a method of performing various treatments such as etching treatment and ansing treatment on a substrate, and a plasma processing apparatus refers to an apparatus designed and manufactured to carry out the various plasma treatments.

Conventionally, such a plasma processing apparatus includes a plasma processing chamber, which is a vacuum container, having a plasma generation raw material gas inlet and an exhaust port, and a plasma processing chamber for converting the plasma generation raw material gas introduced into the plasma treatment chamber into plasma. The apparatus comprises a means for supplying energy such as electromagnetic waves, a substrate to be plasma treated and means for supporting it.

By the way, the plasma treatment relies on the strong activity of the radicals, and by appropriately selecting the generation density of the radicals, the temperature of the substrate to be plasma treated, etc.
The desired plasma treatment is carried out, but in order to increase the processing speed in the plasma treatment method and to perform uniform plasma treatment over a large area, it is necessary to uniformly and in large quantities spread the radicals over a large area. This is the selection of plasma conditions for generation.

Conventionally, 13.56 MHz radio frequency (RF) has been used as the energy to turn raw material gas into plasma, but in recent years, high-density plasma can be efficiently generated by using 2.45 GHz microwave. Plasma processing methods using microwaves have attracted attention because of their potential to improve processing speed in various plasma processings, and many apparatuses for this purpose have been proposed.

For example, as the plasma processing apparatus, especially a plasma CV
Regarding the D device, amorphous silicon (hereinafter referred to as
RA-3i J) and polysilicon (RP-3
It is written as iJ. ), or an insulating deposited film of SiO, SiN, etc., by a plasma CVD method using microwaves (hereinafter referred to as "rMW-PCVD method").

By the way, such conventional MW-PCVD apparatuses can be roughly divided into the following two types.

That is, the first type is published in Japanese Patent Publication No. 58-49295, Japanese Patent Publication No. 43991-1982, and Publication Utility Model Publication No. 62-36.
This is the type seen in Japanese Patent Application No. 240, etc., in which a gas pipe is inserted into or brought into contact with a rectangular waveguide or coaxial line to generate plasma. C
Hereinafter, this method will be referred to as the "method IMW-PCVD apparatus."] The second type is the type found in Japanese Patent Application Laid-open No. 57-133636, etc., and uses electron cyclotron resonance (ECR) in a cavity resonator. ) and extracts plasma using a divergent magnetic field. [Hereinafter, this method will be referred to as "method 2 MW PCVD apparatus." ] As for IMW-PCVD equipment, the equipment shown in Figure 2 can be cited as a typical example
2-36240).

That is, the IMW-PCVD apparatus, as shown in FIG. 2, is composed of a vacuum system, an exhaust system, and a microwave introduction system.

In FIG. 2, the vacuum system is composed of a reaction vessel 22 and a microwave-transparent tube (for example, a quartz tube) having an inner diameter of about 40 m and connected via a gas transport tube 23. The quartz tube is connected to the first gas introduction pipe and is also perpendicular to the microwave waveguide. And inside the reaction container 22,
A second gas introduction pipe is connected, and the raw material gas (silane gas) introduced through the gas introduction pipe is exhausted by an exhaust system (exhaust pipe 24, exhaust pump 25). In the device, the raw material gas (0, gas or N2 gas) introduced from the first gas introduction pipe is
It is turned into plasma by microwave power. The discharge caused by the microwave power is controlled by moving a sliding shorting plate (-plunger) 26 to match the microwave input impedance.

The radicals in the plasma generated in this way are transported to the reaction vessel 22 via the gas transport pipe 23, and react with the silane gas introduced via the second gas introduction pipe, resulting in the formation of a silane gas on the substrate 21. , or an insulating deposited film such as SiN is formed.

As for the method 2 MW-P CVD device, the device shown in FIG. The device configuration and form are almost the same as those of the IMW-PCVD device described above. That is, the vacuum system is composed of a cylindrical plasma generation chamber 31 and a deposition chamber 32 connected thereto, and a microwave introduction window 33 is provided in the plasma generation chamber 31 to maintain a vacuum inside the plasma generation chamber. It is being Plasma conversion chamber 3
1 is connected to a first gas introduction pipe 36 and a microwave waveguide 34, and the plasma generation chamber 31 is almost entirely water-cooled via a cooling water channel 35 provided on its outer periphery. There is.

In addition, the electromagnet 3 is placed concentrically with the plasma generation chamber 31.
7 is arranged, the direction of the magnetic field lines is almost the same as the direction of propagation of the microwave, and electron cyclotron motion is generated so that the direction of the magnetic field lines and the direction of the electric field of the microwave are orthogonal to each other. It looks like this.

For this reason, the plasma generation chamber 31 is designed to have a cavity resonator structure of TE++t (t: natural number) mode. Further, a second gas introduction pipe and an exhaust system are connected to the deposition chamber 32, and the raw material gas and the like introduced into the deposition chamber 32 are exhausted through the exhaust system.

In the 2MW-PCVD apparatus typified by the apparatus configuration shown in FIG. When the magnetic field strength near the wave introduction window 33 is set to 875 Gauss, the reflection of microwave power becomes almost zero, and most of the supplied microwave power is absorbed by the plasma. The hydrogen plasma generated as described above is transported to the deposition chamber 32 along the direction of the lines of magnetic force of the divergent magnetic field, and further transforms the source gas (silane gas) introduced through the second gas introduction pipe into plasma. Generates radicals and deposits a on the substrate 38.
This is where the -3i film is formed.

On the other hand, some examples have been proposed in which microwaves are applied to surface treatment equipment such as nitriding and oxidation using plasma. As described above, there is a plasma surface treatment apparatus characterized by using antenna means for supplying microwaves. (Hereinafter, this method will be referred to as “antenna type microwave plasma surface treatment device.”) Specifically,
The apparatus shown in FIG. 4 can be cited as a typical example (Japanese Patent Publication No. 57-53858).

In other words, the antenna type microwave plasma surface treatment device is
As shown in FIG. 4, it consists of a vacuum system, an exhaust system, and a microwave introduction system.

In FIG. 4, the vacuum system is composed of a reaction vessel 405, a quartz cylinder 411, and a gas inlet 407. N
2 gas cylinders, H! Flowmeter 41 from each gas cylinder
4 and 415, through valves 416 and 417 N! Gas and Nx gas are supplied to the reaction vessel 405 from the gas inlet 407.
will be introduced in

The introduced gas is exhausted through an exhaust port 406 and a pulp 409 by an exhaust system W408. The source gases (Nx gas and H2 gas) introduced into the device are turned into plasma by microwave power.

Specifically, microwaves generated by the microwave type R4 (13) are transmitted toward the reaction vessel 405 via a waveguide 402 and a metal antenna 410, and the transmitted microwave power is transmitted to a quartz tube. Reaction vessel 40 via body 411
5 is reflected towards the inside and turns the raw material gas into plasma.

Microwave matching is performed by plunger 403 and three-stub tuner 404. The surface of the sample piece 413 (for example, a Sl wafer) is modified by the active species in the plasma thus generated.

However, the two conventional types of MW-PCVD mentioned above
The device is suitable for use in solar cells, thin film transistors (TPT) for liquid crystal drivers, line sensors, etc.
Various problems remain when attempting to deposit a -3i:H film onto a large area substrate.

That is, specifically, method IMW-PCVD apparatus and method 2
No matter which MW-PCVD apparatus is used, it is difficult to form a deposited film with uniform quality and thickness over a large area (for example, about 30 cm square).

The reason for this is that in the IMW-PCVD system, the outer diameter of the microwave-transmissive tube is limited by the thickness of the microwave waveguide due to the structure of the device, which is generally contrary to 2.45 GHz for consumer use. Since the long side (inner diameter) dimension of the microwave rectangular waveguide is 109.2 cm or less, the uniformity of the deposited film can only be obtained by at most 10 cm.
It is approximately cm+φ. Also, method 2 MW-P CV
In the D device, since a diverging magnetic field is used, the distribution of magnetic lines of force increases in correlation with the increase in distance from the electromagnet.
Along with this, the film quality and film thickness distribution also increase.

In addition, as a new proposal similar to the 2MW-PCVD method, Japanese Patent Laid-Open No. 63-283 (13) 8 discloses that by additionally placing a magnet near the substrate and making the magnetic field distribution near the substrate uniform, Although there is a disclosure that film quality and film thickness distribution can be improved, even in this device, the uniformity of film quality and film thickness distribution can only be maintained at a diameter of about 200 fl, and when a square substrate is used as the base. So about 140
It is only about n angle.

The above-mentioned conventional problems are the same when performing other plasma treatments, such as dry etching, asher-1 nitriding, and oxidation. Processing is difficult.

On the other hand, the antenna-type microwave plasma processing apparatus (Japanese Patent Publication No. 57-53858) also has some problems.

That is, in the antenna-type microwave plasma processing apparatus, matching of the impedance of microwaves can be apparently performed using the three-stub tuner 404, the plunger 403, etc., but in reality, the quartz cylinder 411 is connected to the reaction vessel 405. There are impedance discontinuities at two locations: the penetrating portion and the conversion portion between the antenna 411 and the rectangular waveguide 402, and a standing wave will be generated between the discontinuity and the tuner. Therefore, a considerable portion of the input microwave power is reflected at the discontinuous portion, so that the microwave power cannot be efficiently supplied to the plasma.

Further, since the microwave power is sequentially radiated into space while propagating on the antenna, attenuation of the microwave occurs in the longitudinal direction of the antenna. Therefore, the intensity of plasma generated using such an antenna is attenuated in the longitudinal direction of the antenna, making it difficult to generate uniform plasma with a large capacity.

In view of the above, there is a desire for early provision of a new microwave plasma processing apparatus that can be applied to large area plasma processing and that solves the various problems described above.

[Purpose of the invention]

The present invention eliminates the above-mentioned problems associated with conventional microwave plasma processing equipment, has high operating rate and work efficiency,
The main object of the present invention is to provide a new microwave plasma processing apparatus that can perform stable plasma processing at all times.

Another object of the present invention is to make it possible to uniformly and homogeneously perform desired plasma treatment on a large area of a substrate by devising a microwave introduction method without using a large electromagnet as in the ECR method. The object of the present invention is to provide a new microwave plasma processing apparatus that can

Still another object of the present invention is to ensure that the microwave input impedance is always matched regardless of the ionization cross section of the gas and even during discharge, and that microwave power is effectively utilized to achieve desired plasma processing in large quantities. An object of the present invention is to provide a new microwave plasma processing apparatus that enables the following.

[Structure and effects of the invention]

The inventors of the present invention have conducted extensive research to achieve the above-mentioned objective of uniform plasma processing on large area substrates, which has been difficult with conventional microwave plasma processing apparatuses, and have completed the apparatus of the present invention. It's arrived. The outline is as follows.

That is, the apparatus of the present invention includes a closed container, a means for evacuating the closed container, a means for introducing raw material gas for plasma generation into the closed container, and a microwave power for generating plasma in the closed container. A microwave plasma processing apparatus comprising a supply means, the microwave power supply means being a front.

A center conductor penetrated into the sealed container, a rotationally symmetrical microwave transparent member that encloses the center conductor in the sealed container and separates the central conductor from the plasma, and the microwave transparent member. This microwave plasma processing apparatus is characterized in that it is a coaxial line constituted by a rotationally symmetrical conductive member disposed so as to encompass the coaxial line.

In the device of the present invention, the tip of the center conductor is an electromagnetic open end.

At least two or more tuning means are provided on the coaxial line, and one of the tuning means is an insertion length adjustment mechanism of the center conductor into the closed container.

Further, the microwave power supply means constitutes a semi-coaxial resonator.

In the apparatus of the present invention, the conductive member has a porous structure, and the substrate to be plasma treated is disposed further outside the conductive member.

In the apparatus of the present invention, the means for introducing the source gas for plasma generation is arranged such that the source gas is introduced into a space substantially isolated by the conductive member and the microwave transparent member. Set up

Further, in the apparatus of the present invention, the means for introducing the raw material gas for plasma generation is constituted by two gas introduction pipes, and one gas introduction pipe is substantially composed of the electrically conductive member and the microwave transparent member. The material gas is introduced into a space that is physically isolated, and hydrogen and/or inert gas is introduced from the gas introduction pipe, and the other gas introduction pipe is connected to the conductive member. It is arranged between the plasma processing target substrate and the gas introduction pipe to introduce a raw material gas for forming a deposited film.

In the apparatus of the present invention, the conductive member also serves as a plasma-treated substrate and/or a substrate susceptor.

Further, the conductive member may have a cylindrical shape, and the microwave transparent member may have a cylindrical shape, a truncated conical shape, or a conical shape.

Furthermore, the microwave transparent member is provided with a cooling means, and the cooling means is an air flow flowing along the inner peripheral surface of the microwave transparent member.

The airflow passes through the interior of the central conductor having a hollow structure and is emitted from the tip of the central conductor on the side that penetrates into the closed container.

According to the technical analysis conducted by the inventor prior to completing the present invention, in the conventional type IMW-PCVD apparatus and the 2MW-PCVD replacement type, the area where the microwave power is injected into the plasma, that is, the microwave Since the area where the waves and plasma come into contact is relatively small, it is difficult to generate and maintain uniform plasma over a large volume of space, even considering the natural diffusion of plasma. In the case of antenna-type microwave plasma processing equipment, the area where the microwaves and plasma come into contact can be increased, but since the microwaves are continuously radiated while being transmitted through the antenna, they are directed toward the tip of the antenna. The attenuation of the microwave power became very large as the antenna progressed, resulting in a decrease in plasma intensity toward the tip of the antenna.

Therefore, in order to achieve plasma uniformity in the apparatus of the present invention, microwave power is injected into the plasma from a wide area, and the electric field strength of the microwave injected into the plasma is approximately constant in the length direction of the antenna. so that it is maintained.

As for the device configuration to realize these, the plasma itself forms part of the microwave transmission path, or the plasma generation space is surrounded by a conductive member, and radiation is emitted from the antenna into the plasma generation space. What is necessary is to transmit the generated microwaves without leaking them to the outside.

In the device of the present invention, a center conductor, a rotationally symmetrical microwave transparent member, and a rotationally symmetrical conductive member are arranged coaxially, and the center conductor is placed in a closed container so as to be parallel to the base. Since the microwave power is transmitted through the coaxial line composed of the center conductor and the conductive member, the distance between the base body and the coaxial line is relatively short, and the microwave power is transmitted in the longitudinal direction of the center conductor. As a result, microwaves are radiated almost uniformly in the longitudinal direction of the center conductor, and plasma is uniformly generated within the space formed by the mithalo wave transparent member and the conductive member. It can be caused and maintained.

Here, if the plasma density is higher than the cutoff density,
Microwaves are blocked at the plasma surface, and when the plasma density is less than or equal to the cutoff density, the microwaves can propagate in the plasma. In particular, in the case of 2.45 GHz microwave, the cutoff density is 7.4 x 10'' (
3-').

Specifically, as the microwave power input into the sealed container is increased through the coaxial line, the amount of gas that is introduced into the sealed container and ionized by the microwave power and its flow rate increases. Then, the power absorbed by the microwave into the plasma is saturated, and the plasma density reaches the above-mentioned cutoff density.

If the input microwave power is further increased, the microwaves will propagate in the longitudinal direction of the center conductor due to this saturation effect.
As a result, the plasma density uniformly approaches the cutoff density, making it easy to uniformly perform plasma processing over a large area.

However, the dielectric loss tan δ (tan delta) of the microwave transparent member in the microwave band, and the heat resistance and heat resistance of the transparent member against the temperature rise that occurs when the microwave transparent member is exposed to plasma. Impact characteristics/
Depending on thermal conductivity and the like, the above-mentioned microwave power that can be input may be restricted. In such a case, since the microwave power input into the sealed container is small,
The microwave power differs between the introduction part of the center conductor into the sealed container and the tip part, and as a result, the plasma density has an unacceptable spatial distribution.In order to avoid this and perform uniform plasma treatment over a large area. In this method, a microwave transparent member having a truncated cone shape or a conical shape that gradually becomes thicker in accordance with the direction of propagation of the microwave is arranged, and the distance between the base body and the coaxial line is adjusted according to the direction of propagation of the microwave. Just make it narrower to compensate for the loss of microwave power.

In the apparatus of the present invention, as described above, the microwave is propagated almost uniformly in the longitudinal direction of the central conductor regardless of the plasma density, so that plasma can be generated and maintained over a large area.

In addition, in the apparatus of the present invention, in order to efficiently input microwave power into the plasma, the center conductor constituting the coaxial line is penetrated into the inside of the sealed container from one direction of the wall surface of the sealed container. at least two tuning means are arranged in the coaxial line, and one of the tuning means is an insertion length adjustment mechanism for the center conductor. let

In the device of the present invention, since the tip of the center conductor forms an electromagnetically open end, the microwave transmitted to the tip of the center conductor is completely reflected, producing a reflected wave and a standing wave. , In order to prevent the standing wave from going backwards along the coaxial line and returning to the microwave generation source, at least two
It is preferable to provide more than one tuning means, and one specific example of the tuning means is a center conductor insertion length adjustment mechanism. That is, by adjusting the insertion length of the center conductor into the closed container, the phase is adjusted, and at the same time, the microwave is supplied by adjusting other tuning means, specifically, the coaxial plunger. The amplitude is adjusted by changing the degree of coupling with the rectangular waveguide, and by matching the reflected wave so that it does not return to the rectangular waveguide, microwave power is efficiently transferred to the plasma. It becomes possible to invest in

Here, plasma control parameters such as gas type, pressure,
By changing the flow rate, etc., the amount of microwave power absorbed by the plasma changes, and even if the same microwave power is input, a relatively uniform plasma will be generated in a plasma with poor microwave absorption efficiency. , there is a problem that the reflected power is large and microwaves cannot be efficiently introduced into the plasma.

On the other hand, in a plasma that has very high microwave absorption efficiency, microwave power is absorbed efficiently, but on the other hand, most of the microwave power is absorbed by the plasma near the supply side, and the microwave power is absorbed at the tip of the antenna. There is a problem that the plasma is greatly attenuated, and as a result, the plasma becomes non-uniform.

In order to efficiently generate uniform plasma in the apparatus of the present invention, the amount of microwave power input may be adjusted depending on the gas type, pressure, flow rate, etc.

For example, specifically, in the case of a plasma with good microwave absorption efficiency, the amount of microwave power input is increased to maintain uniformity, and conversely, in the case of a plasma with poor microwave absorption efficiency, the microwave power input is increased. What is necessary is to reduce the input amount to eliminate the reflected power of the microwave.

Furthermore, for plasma with poor microwave absorption efficiency,
When it is desired to increase the input amount of microwave power while suppressing reflected power, a semi-coaxial resonator is configured by the center conductor and a rotationally symmetrical conductive member coaxially disposed around the center conductor. By increasing the electric field strength of the microwave within the semi-coaxial resonator, microwave power can be efficiently supplied to the plasma. In this way, even in a plasma with poor microwave absorption efficiency, the plasma intensity can be increased to absorb microwaves.

That is, in the apparatus of the present invention, for plasma with poor microwave absorption efficiency, the antenna means has a semi-coaxial resonator structure to accumulate microwave power, thereby generating a strong standing wave. This allows the plasma to absorb approximately the same amount of power as the input power. Since the electric field strength at the antinode of the standing wave generated in this way can be made almost the same near the microwave power supply side and at the tip of the central conductor, the plasma in the vicinity of each antinode The strength is not much different.

In addition, in the apparatus of the present invention, the plasma intensity distribution caused by the standing wave is relaxed by increasing the diffusion of the raw material gas turned into plasma by lowering the pressure, and is more relaxed than the original electric field distribution of the standing wave. In addition, TE
By using an M-mode coaxial line, the wavelength within the tube can be set to be the shortest compared to other modes, and by providing the microwave transparent member having a relative dielectric constant of 1 or more in the coaxial line, the wavelength within the tube can be further shortened. be able to.

In this way, the distance between the antinode and the node of the standing wave can be made relatively short, so that the intensity distribution of the plasma caused by the standing wave can be made almost uniform.

That is, in the device of the present invention, by configuring a semi-coaxial resonator with the center conductor and the conductive member, the microwaves generated in the transmission process peculiar to the antenna can be suppressed by the plasma having poor microwave absorption efficiency. It is possible to improve non-uniformity such as a decrease in plasma intensity in the longitudinal direction of the antenna due to wave attenuation and periodic changes in plasma intensity due to standing waves, and to efficiently supply microwaves to plasma. This makes it possible to generate and maintain uniform plasma in the longitudinal direction of the antenna.

In the apparatus of the present invention, the rotationally symmetrical conductive member has a porous structure, and the substrate to be plasma treated is disposed further outside the rotationally symmetrical conductive member, so that the plasma source is connected to the plasma source. By isolating the substrate to be treated with the porous conductive member, it is possible to reduce plasma damage to the substrate to be plasma treated and to suppress the temperature rise of the substrate. Plasma treatment on small substrates becomes possible.

In the apparatus of the present invention, the means for introducing the source gas for plasma generation is arranged such that the source gas is introduced into a space substantially isolated by the conductive member and the microwave transparent member. By doing so, the flow of the raw material gas that has been turned into plasma in the space can be directed from the inside to the outside of the conductive member, and the raw material gas that has been turned into plasma can be efficiently transported to the substrate to be plasma treated. can.

In the apparatus of the present invention, the means for introducing the raw material gas for plasma generation is constituted by two gas introduction pipes, and one gas introduction pipe is substantially constituted by the porous conductive member and the microwave transparent member. The other gas introduction pipe is arranged between the porous conductive member and the deposited film forming substrate, and especially the former By introducing a raw material gas such as hydrogen and/or inert gas that does not form a film by itself from the gas introduction pipe, no film will be formed on the outer wall soil of the microwave transparent member even when plasma CVD is performed. Film-like plasma can be formed to suppress film deposition on the microwave transparent member. By doing so, even when forming a microwave-absorbing deposited film, microwaves can be stably supplied to the plasma over a long period of time, and the stability of the plasma is further improved.

In the apparatus of the present invention, when the rotationally symmetrical conductive member doubles as the substrate to be plasma treated and/or the substrate susceptor, the substrate to be plasma treated is directly exposed to the plasma, but on the other hand, it is extremely High-speed plasma processing becomes possible. Generally, plasma damage to the plasma-treated substrate is caused by high-energy charged particles on the substrate, but in the apparatus of the present invention, by applying an electrical bias to the plasma-treated substrate, The energy of the charged particles incident on the substrate to be plasma treated can be controlled.

However, high-speed processing can be achieved by appropriately controlling the energy of the charged particles.

In the apparatus of the present invention, by making the rotationally symmetrical conductive member cylindrical, the microwave electric field is uniform without distortion in the circumferential direction of the rotationally symmetrical member, so that uniform plasma can be formed. .

In addition, the shape is simplified, the device can be easily designed and manufactured, and reproducibility can be easily obtained. Similarly, by forming the rotationally symmetrical microwave transparent member into a cylindrical, truncated, or conical shape, the same effect as that of the conductive member can be obtained.

However, the microwave plasma processing apparatus of the present invention can be applied to plasma processing such as plasma CVD, dry etching, plasma ashing, plasma oxidation, and plasma nitridation.

Among them, thin film transistors for solar cells and liquid crystal drivers (
It is desirable to apply the microwave plasma processing apparatus of the present invention to process equipment that requires plasma uniformity over a large area, such as TPT) and line sensors.

Specifically, the functional deposited film that can be formed by the apparatus of the present invention includes Si, Ge, and C, regardless of whether it is amorphous or crystalline.
etc. So-called group III raw conductor thin films, 5iGs, SIC, 5iS
n etc. so-called group II alloy semiconductor 11M, GaAg+GaP
, 'GaSb, InP.

So-called m-v group compound semiconductor fil, such as InAs! , and Zn5e, ZnS, ZnTe, CdS, Cd5a.

Examples include so-called II-Vl group compound semiconductor thin films such as CdTe. The raw material gas for forming the functional deposited film used in such a case may include hydrides, halides, organometallic compounds, etc. of the constituent elements of the various semiconductor thin films described above.

Of course, these raw material compounds can be used not only alone, but also in combination of two or more. In addition, these raw material compounds are He * N e + A r , K r ,
Xe.

It may be introduced in a mixture with a rare gas such as Rn and a diluent gas such as H*, HF, HCj, etc.

Further, the semiconductor thin film can perform valence electron control and forbidden band width control. Now, specifically, a raw material compound containing an element serving as a valence electron control agent or a forbidden band width control agent may be used alone or in combination with the deposited film forming raw material gas or the diluent gas.

The apparatus of the present invention is also suitable for forming insulating films for semiconductor devices such as TPT and line sensors. 510 by appropriately selecting and using compounds contained as constituent elements in the raw material gas.
g, an insulating film such as SiN can be formed.

Furthermore, the apparatus of the present invention can be suitably used as a dry etching apparatus in the manufacturing process of semiconductor devices and the like. Specifically, the processing gases used at that time include CFa, CFalos,
Examples include SFh, NFs, and Cl1F. Note that these processing gases can also be used in combination.

Further, the apparatus of the present invention removes the resist material used in the patterning process of the semiconductor device.
It can also be suitably used as a device for so-called ansing processing. The processing gases used at that time include Ol, Oz/HtO-Oz/N*, Ot/
H, etc. can be mentioned.

Note that these processing gases can also be used in combination.

[Equipment example]

Hereinafter, the microwave plasma processing apparatus of the present invention will be explained in detail with reference to the drawings, but the present invention is not limited to these apparatus examples in any way.

FIG. 1A and 1B of Apparatus 1) is a schematic cross-sectional view of a microwave plasma processing apparatus that best represents the features of the apparatus of the present invention.

In FIG. 1 (1al and Tb), 1 (13) is a microwave generation source, 102 is a rectangular waveguide, and 103 is a rectangular shutter.
Dov Langer, 104 is the center conductor of the coaxial line, lO
5 is an outer conductor of the coaxial line, 106 is a coaxial short plunger, 107 is a cylindrical microwave transparent member, 108
109 is a closed container, 109 is a porous cylindrical conductive member, 11
0, 111 is a gas inlet, 112 is an exhaust port, 113 is a substrate to be plasma treated, and ] 14 is a substrate susceptor; 11
5 indicates an O-ring.

In FIG. 1al, the microwave generated in the microwave source 1 (13) is transmitted through the rectangular waveguide 102, aligned in the rectangular short plunger 103 and the coaxial short plunger 106, and then the central conductor 104 and an outer conductor 105.

The coaxial line composed of the center conductor 104 and the outer conductor 105 is arranged such that the central axis of the coaxial line is at the center of the E plane of the rectangular waveguide and perpendicular to the E plane of the rectangular waveguide. The TE mode of the rectangular waveguide 102 is converted into the 78M mode of the coaxial line.

A rectangular short plunger 103 is used to vary the phase of the microwave at the coaxial line fastening position within the rectangular waveguide 102, and a similar coaxial Szilard plunger 106 is used.
is used to vary the phase of the microwave at the rectangular waveguide fastening position in the coaxial line. Alignment can be achieved by using the rectangular short plunger 103 and the coaxial short plunger 106 and performing a phase adjustment operation.

Here, it is preferable to use materials with low electrical resistivity for the center conductor 104 and outer conductor 105 of the coaxial line in order to reduce ohmic loss due to surface current generated with microwave transmission. Since the short plunger 106 moves while making relatively strong contact with the abrasive, it is preferable that it has excellent abrasion resistance. Therefore, specifically, the material is copper, brass, or stainless steel that has been plated or gold plated. I can list the following.

Also, between the coaxial short plunger 106 and the center conductor 104 of the coaxial line, between the outer conductor 105, and between the rectangular short plunger 103 and the rectangular waveguide 102.
In order to prevent abnormal discharge between the two, it is desirable to maintain good contact with a spring material such as phosphor bronze.

Here, the microwave transmitted within the coaxial line is transmitted because the diameter of the outer conductor 105 as a transmission path and the porous cylindrical conductive member 109 rapidly expands at the connection part. , the connecting portion serves as a microwave reflecting surface. Therefore, in the space surrounded by the center conductor 104 and the porous cylindrical conductive member 109, the center conductor 104
By adjusting the insertion length of the resonator to achieve resonance conditions, it can be made to work as a semi-coaxial resonator.

The porous cylindrical conductive member 109 is preferably made of a material that has a low resistance surface and is not easily spattered by plasma or releases impurities. Specifically, stainless steel, A1 etc. can be mentioned. The shape of the pores formed in the porous cylindrical conductive member is not particularly limited, but the maximum dimension of the pores is preferably one wavelength of microwaves so as to sufficiently block microwaves.
/10 wavelength or less is desirable.

A cylindrical microwave transparent member 109 is inserted into the coaxial line having the semi-coaxial resonator structure.

The cylindrical microwave transparent member 109 has good airtightness and microwave transparency, that is, tan δ (tan delta) in the microwave band used is 4X1.
0-' or less is preferably used. in particular,
The cylindrical microwave transparent member 109, which may be made of quartz, beryllia, alumina, etc., is fixed at the flange using a vacuum sealing ring 115, and the inside is kept in the atmosphere and the outside is kept in a vacuum. It looks like this.

Further, a gas introduction port +10 for introducing a plasma generating gas is provided between the cylindrical microwave transparent member 109 and the porous cylindrical conductive member.

Inside the sealed chamber 1108, a deposited film forming substrate 113 and a substrate susceptor 1!4 are disposed outside the porous cylindrical conductive member 109, and the plasma generating raw material gas and the plasma generating raw material gas are disposed on the wall surface thereof. is equipped with a gas inlet 111 for introducing another gas, and an exhaust port 112 connected to an exhaust pump (not shown).

In the zero-layout example, a brass tube plated with Ag and having an outer diameter of 12.7 amφ was used as the center conductor 104 of the coaxial line. The outer conductor 105 has an inner diameter of 50
0 using a brass tube with Agme and Ki of Otorikaiφ
The cylindrical microwave transparent member 107 has an outer diameter of 46
A flanged quartz tube with wφ, wall thickness of 2 mm, and length of 400 mm and sealed at one end was used. Further, a porous cylindrical conductive member 10
9 was a stainless steel punching plate having a cylindrical shape with an outer diameter of 80 m and a length of 400 D, with holes having a hole diameter of 3 mm and a pitch of 5 mm.

The microwave plasma processing equipment of this equipment example is MW-PCV.
The operating method when operated as a D device will be described in detail below. First, a vacuum pump (not shown) connected to the exhaust port 112, preferably a turbo molecular pump, a mechanical booster pump, a rotary pump, etc., is used to pump the inside of the closed container 108 into the airtight container 108.
High vacuum is evacuated to approximately 10-' Torr. Subsequently, the substrate 113 for forming a deposited film is heated to a predetermined temperature (200° C. to 250° C.) by a heater (not shown) in the substrate susceptor 114.
When the temperature is stabilized, Hx, Ar, He, etc. are introduced from the gas introduction port 11G, and silane gas, etc. is introduced from the gas introduction port 111. At this time, the flow rate of each raw material gas is adjusted using a mass flow controller (not shown), etc., and the exhaust port 11 is adjusted as necessary.
A conductance adjustment valve (not shown) provided at 2 is operated to maintain a predetermined pressure in the closed container 108.

Next, the microwave generation source 1 (13) generates microwaves. The microwave passes through the rectangular waveguide 102,
Center conductor 104 and outer conductor 105 and rectangular waveguide 102
The signal is transmitted to the connection point. Here, the coaxial short plunger 106, the rectangular short plunger 103, the central conductor The insertion lengths of 104 are adjusted respectively.

The adjustment procedure is as follows: First, slide the center conductor 104 in the horizontal direction in the figure to change the insertion length and adjust the half-coaxial resonator to the resonance condition. Next, insert the coaxial short plunger 1.
05 to adjust the phase of the coaxial line section, and the rectangular waveguide 10
2 and the degree of coupling between the coaxial line section. The rectangular short plunger 103 is used for fine adjustment after most of the transmitted microwave has been transmitted to the coaxial line and the semi-coaxial resonator by adjusting the insertion length of the center conductor 104 and the coaxial Szilard plunger 105. In this way, microwaves are transmitted along a coaxial line and stored in a semi-coaxial resonator,
It is possible to obtain a microwave electric field strength sufficient to turn the raw material gas into plasma within the semi-coaxial resonator.

A method for generating and adjusting plasma using this device will be specifically explained. First, the plasma control parameters are A r 5
0 sccm, pressure I x 10-'Torr, and microwave power of 400 W, the center conductor 1504 and the cylindrical conductive member 109 constitute a coaxial line before discharge, and there is no microwave permeability in the coaxial line. Since it contains a quartz tube with an outer diameter of 46mm and a wall thickness of 2fi as a member, the wavelength of the transmitted microwave is 122mm inside the tube in vacuum.
It is shorter than 4fi, and is about 70 cranes. Therefore, the insertion length of the center conductor 104 from the end surface of the sealed container is set to 70X (n/
2+1/4)ta, a resonance state can theoretically be obtained. Therefore, first, the insertion length of the center conductor is set to about 368 fins corresponding to n=10.

Next, while monitoring the reflected power using a microwave power meter around this position, the insertion length is adjusted to #A so that the reflected power is minimized.

Furthermore, by sliding the coaxial short plunger 106 to finely adjust the degree of coupling, the reflected power is further reduced.
As a result, the input power increases and discharge occurs. Even if a discharge occurs, a small amount of reflected power usually remains.

The reflected power generated here is due to the fact that the absorption of microwaves increases due to plasma generation and the degree of coupling becomes smaller than the matching condition, and also because the complex dielectric constant of the plasma deviates from the resonant state.

The microwave transmission mode within the semi-coaxial resonator is TEM.
mode', even when the plasma acts as an external conductor, there is less change in the resonance conditions compared to other microwave modes, and even in the above adjustment example, the center conductor 10
By inserting about 15 more pieces of 4, the resonance condition is again obtained, and by fine-tuning -106 during the coaxial short plunge and readjusting the degree of coupling, the reflected power can be reduced to approximately 5% or less of the incident power. I was able to keep it down to

By performing the above-described operations, plasma can be uniformly generated over a large area regardless of the plasma density generated.

Furthermore, Ar is introduced from the gas inlet 110.

Hz, I(e, etc.) are turned into plasma, and the generated ions, radicals, etc. are introduced into the space in which the deposited film forming substrate is provided through the holes of the porous cylindrical member 109, and the gas inlet 111 reacts with the raw material gas for forming a deposited film such as silane introduced from the reactor to generate active species for forming a deposited film, and a-3i:8M etc. A deposited film is formed.

Furthermore, even when the microwave plasma processing apparatus of this apparatus example is operated as a plasma processing apparatus other than a plasma CVD apparatus, there is no change in the apparatus except for the difference in the raw material gas for plasma generation, and there is no change in the operating method. do not have.

Cap 1 Spot 1 In device example 1, a porous cylindrical conductive member is provided,
In this example, the base susceptor 114 is made of a cylindrical conductive member, although it has the role of an external conductor of the semi-coaxial resonator.

That is, in this device example, the porous cylindrical conductive member is removed from the device shown in FIG.
In this example of the apparatus, the raw material gas for plasma generation is introduced only through the gas inlet 111 provided between the cylindrical microwave transparent member 107 and the base susceptor 114.

The microwave plasma processing equipment shown in this equipment example is MW-P.
The operating method when operating as a CVD apparatus is the same as that described in apparatus example 1 except that the film-forming raw material gas is introduced only through the gas inlet 111. Further, other plasma treatments are also similar to the method described in Apparatus Example 1.

The cylindrical microwave transparent member 107 has an outer diameter of 46
Using a flanged quartz tube with opposite ends, the base susceptor 114 has an inner diameter of 150 mφ and a length of 400 m, and has a heater mechanism (not shown).
It has a cylindrical structure made of stainless steel.

Furthermore, even when the microwave plasma processing apparatus of this apparatus example is operated as a plasma processing apparatus other than a plasma CVD apparatus, there is no change in the apparatus except for the difference in the raw material gas for plasma generation, and there is no change in the operating method. do not have.

[Plasma treatment example]

Hereinafter, specific processing examples using the microwave plasma processing apparatus of the present invention will be shown, but the present invention is not limited to these processing examples in any way.

Using the microwave plasma processing apparatus of the present invention (Fig. 1) described in Sokoho Charcoal Apparatus Example 1, it was operated as a microwave plasma CVD apparatus to process a Corning #7059 glass substrate (1
3 inches x 3 inches) were arranged along the outer periphery of a porous cylindrical conductive member, and a-31:Hll was deposited under the conditions shown in Table 1.

Table 1 Obtained a-3i:) (A6 comb-shaped gap electrode (width 250 μm, length 5 mm) was deposited on IIl by resistance heating evaporation method, and irradiated with AM-1 light (100 mW/c+4). The photocurrent value under the HP 4140 and the dark current value in the dark
B was used to determine the attractive conductivity σ, (S/3) and dark conductivity σa (S/am), and the activation energy Ea was determined from the rate of change in dark conductivity from room temperature to 150°C. (eV) was determined. Further, the optical band gap "go#t (eV)" was determined by a transmission measurement method.

The results are shown in Table 2.Measurements were made for all sample pieces and the average value is shown.

From these evaluation results, the obtained film had high practical value and was excellent in uniformity in both properties and film thickness.

Table 3 shows the results of the same evaluation as in 2nd Surface Film Example 1. All of them exhibited properties with high practical value and were excellent in uniformity in both properties and film thickness.

S i Ha 100 sccms pressure 2 x 10-” Torr, microwave power 50 as explained in Table 3 Equipment Example 2
As a result of depositing the a-3i:H film at 0W, the deposition rate was 50 people/s and the thickness distribution was ±3% (30Q Tsuru x 150wφ), and both the deposition rate and film thickness uniformity were sufficient for practical use over a large area. It was the result.

In addition, the characteristics of the formed a-3l:HlliJ were evaluated by using the microwave plasma processing apparatus of the present invention described in Apparatus Example 1 and operating it as a microwave plasma ashing apparatus under the conditions shown in Table 4. Ashing treatment was performed on a resist (product name: 0DURIO13, manufactured by Tokyo Ohka), which was spin-coded on a Corning #7059 glass substrate and heat-baked at 200° C. for 10 minutes. However, the porous cylindrical conductive member is the same as in Table 1.

Table 4: The a-3i:H film formed in Film Formation Example 1 was etched.

Table 5 Ashing speed under the above processing conditions is 1.4 μm/5
The distribution of ins ashing speed was 300w x 150 fin angle with an upper 2°0% distribution.

ヱ7f舅1 Using the apparatus of the present invention described in Apparatus Example 2, it was operated as a microwave plasma ashing apparatus, and the resist ashing process was performed under the same conditions as in Ashing Example 1, as shown in Table 4. Ta.

The ashing speed under the above processing conditions is 1.7μm/5
The distribution of ins ashing speed was 12.2% at 300 m x 150 Tsuru angle.

E±ll■1 The microwave plasma processing apparatus of the present invention explained in Apparatus Example 1 was operated as a microwave plasma etching apparatus under the conditions shown in Table 5, and as a result, the etching rate was 0.8 μm/ sin, the etching rate distribution was 2.1% above an area of 300 m x 150 cranes.

王ヱ±l久舅J The device of the present invention explained in device example 2! The a-3i:H film formed in Film Formation Example 1 was etched under the conditions shown in Table 5 using a microwave plasma etching apparatus.

As a result, the etching speed was 1.1 μm/min, and the etching speed distribution was 12 mm in an area of 300 mm x 150 mm.
．． It was 2%.

[Summary of the effects of the invention]

According to the microwave plasma processing apparatus of the present invention, the airtight container includes a central conductor of a coaxial line as a microwave power supply means, a rotationally symmetrical microwave transparent member, and a rotationally symmetrical conductive member. By arranging the coaxial line, plasma can be generated uniformly, stably, and with good reproducibility in the longitudinal direction of the antenna. Therefore, it is possible to obtain uniform processing speed over a large area and properties of the substrate after processing, which has been difficult in conventional microwave plasma processing apparatuses.

By using the apparatus of the present invention, plasma processing with excellent characteristic stability can be performed at high speed and with little plasma damage in plasma processing such as plasma CVD, dry etching, and plasma ashing.

[Brief explanation of drawings]

FIG. 1 (al is a schematic cross-sectional view of the microwave plasma processing apparatus of the present invention. First opening) is a perspective explanatory view of the main microwave introduction part of the microwave plasma processing apparatus of the present invention. FIGS. 2 to 4 are explanatory diagrams of conventional microwave processing apparatuses, respectively. In FIG. 1, 1(13)...Microwave generation source, 102...Rectangular waveguide, 103.106...Short plunger,
104... Center conductor of coaxial line, 105... Outer conductor of coaxial line, 107... Cylindrical microwave transparent member, 10B... Airtight container, 109... Porous cylindrical conductive material Member, 110, 111... Gas inlet, 11
2... Exhaust port, 113... Substrate to be plasma treated, 1
14...Base susceptor, 115...O ring. In FIG. 2, 21...Substrate, 22...Reaction vessel, 23...Gas transport pipe, 24...Exhaust pipe, 25...Exhaust pump, 2
6 Plunger In FIG. 3, 31... Plasmaization chamber, 32... Deposition chamber, 33...
・Microwave introduction window, 34...Microwave waveguide, 3
5... Cooling water channel, 36... Gas introduction pipe, 37...
Electromagnet, 38... board. In FIG. 4, 4(13)...Microwave power source, 402...Rectangular waveguide, 403...In plunge-1404...Three-stuff chainer, 405...Reaction vessel, 406...
...Exhaust port, 407...Gas inlet, 408...Exhaust device, 409...Valve, 410...Metallic antenna, 411...Quartz cylinder, 412...Sample susceptor, 413...Sample piece, 414,415...Flowmeter, 416,417...Valve. Figure 2 Figure 3

Claims (15)

[Claims] (1) Consisting of a sealed container, means for evacuating the sealed container, means for introducing raw material gas for plasma generation into the sealed container, and microwave power supply means for generating plasma in the sealed container. A microwave plasma processing apparatus, wherein the microwave power supply means includes a center conductor penetrated into the closed container, includes the center conductor in the closed container, and separates the center conductor from the plasma. A coaxial line comprising a rotationally symmetrical microwave transparent member and a rotationally symmetrical conductive member disposed to encompass the microwave transparent member. Plasma processing equipment. (2) The microwave plasma processing apparatus according to claim 1, wherein the tip of the center conductor is an electromagnetic open end. (3) The microwave plasma processing apparatus according to claim 2, further comprising at least two or more tuning means on the coaxial line. (4) The microwave plasma processing apparatus according to claim 3, wherein one of the tuning means is a mechanism for adjusting the insertion length of the center conductor into the closed container. (5) The microwave plasma processing apparatus according to claim 2, wherein the microwave power supply means constitutes a semi-coaxial resonator. (6) The microwave plasma processing apparatus according to claim 1, wherein the conductive member has a porous structure. (7) The microwave plasma processing apparatus according to claim 6, further comprising a plasma-treated substrate disposed further outside the conductive member. (8) The means for introducing the raw material gas for plasma generation is arranged so that the raw material gas is introduced into a space substantially isolated by the monoconductive member and the microwave transparent member. The microwave plasma processing apparatus according to claim 7. (9) The means for introducing the raw material gas for plasma generation is constituted by two gas introduction pipes, one of which is substantially isolated by the conductive member and the microwave transparent member. hydrogen and/or inert gas is introduced from the gas introduction pipe, and the other gas introduction pipe is arranged so that the source gas is introduced into the space where the conductive member and the substrate to be plasma treated are connected. from the gas introduction pipe,
8. The microwave plasma processing apparatus according to claim 7, wherein a source gas for forming a deposited film is introduced. (10) The microwave plasma processing apparatus according to claim 1, wherein the conductive member also serves as a substrate to be plasma treated and/or a substrate susceptor. (11) Claim 1, wherein the conductive member has a cylindrical shape.
The microwave plasma processing apparatus described in . (12) The shape of the microwave transparent member is cylindrical;
The microwave plasma processing apparatus according to claim 1, which has a truncated cone shape or a conical shape. (13) The microwave plasma processing apparatus according to claim 1, wherein the microwave transparent member is provided with a cooling means. (14) The microwave plasma processing apparatus according to claim 13, wherein the cooling means is an air flow flowing along the inner peripheral surface of the microwave transparent member. (15) The microwave plasma treatment according to claim 14, wherein the air flow is emitted from the tip portion of the center conductor on the side penetrated into the closed container through the interior of the center conductor having a hollow structure. Device.