JPS63217628A - Plasma processing device - Google Patents

Abstract

PURPOSE:To increase the activated concentration of reactive gas as well as microwave suction efficiency by a method wherein an activation chamber is assumed to be a microwave cavity resonator with a microwave leading-in port to produce high concentration plasma by means of feeding the microwaves. CONSTITUTION:Microwaves are oscillated by a microwave oscillating source 14 to match impressed microwaves with an activation chamber 1 by stubs 13a, 13b and 13c of a tuner 13. Thus, the microwaves running into the activation chamber 1 through leading-in member 3 are formed into standing waves so that reactive gas fed from a feed port 4 by this electric field may be ionized to bring about plasma state. At this time, overall surface of protruding part 3a from a leading-in member 3 is changed into highly concentrated plasma so that the microwaves may run into the activation chamber 1 from overall surface of protruding part 3a of leading-in member 3 to feed plasma of reactive gas with energy. Through these procedures, a plasma processor with resist removing capacity subjected to no damage due to plasma and no pollution by impurity as well as high speed can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma processing apparatus, and particularly to a plasma processing apparatus used for removing photoresist.

[Conventional technology]

A plasma processing apparatus that activates gas to cause a chemical reaction such as ashing on photoresist is disclosed in, for example, Japanese Patent Laid-Open No. 52-1
It is disclosed in Japanese Patent No. 1175. The disclosed plasma processing apparatus includes a quartz activation chamber provided in a part of a microwave cavity resonator, supplies oxygen gas as a raw material gas to this chamber, evacuates the chamber to a predetermined degree of vacuum, and supplies microwave power. The system is configured to generate plasma in the activation chamber, and transport oxygen excited and activated by the plasma (hereinafter referred to as activated oxygen) to the reaction chamber to ash the resist. This plasma processing equipment.

Since the distance between the activation chamber and the reaction chamber is long and the plasma disappears during transportation, the resist is ashed only by activated carbon. Therefore, the object to be treated is not damaged by the plasma, but since the transportation distance is long, activated oxygen also disappears during transportation, and the ratio of activated oxygen in the reaction chamber is significantly smaller than in the activation chamber. Regarding this point, consideration has been given to reducing the concentration drop during transportation by changing the type of activated substance and the combination of substances that collide with it, but a decrease in the concentration of activated oxygen during transportation cannot be avoided. .

One plasma processing apparatus that solves this drawback is disclosed in, for example, Japanese Patent Laid-Open No. 56-96841. In the disclosed plasma device, in order to prevent concentration reduction due to transport of activated oxygen, instead of generating plasma in an activation chamber and transporting it, the plasma device generates microwave plasma in a reaction chamber and uses a method in which activated oxygen is generated at the generation part of activated oxygen. Processing speed was increased by performing resist ashing processing. However, this plasma processing apparatus did not take into account damage caused by plasma. In this respect, for example, JP-A-57-768
The plasma processing apparatus disclosed in Publication No. 44 includes a microwave shielding metal plate provided above the object to be processed in a reaction chamber, and shields the microwave and plasma above the object to be processed. Prevents damage caused by plasma.

However, since the activation chamber and processing chamber are the same in this plasma processing equipment, the charged particles in the plasma collide with the metal plate for plasma shielding, causing sputtering of the metal plate surface and the material of the metal plate. The particles fly out into the reaction chamber and adhere to the objects to be processed, causing contamination. In addition, in this plasma processing apparatus, microwaves are introduced into the reaction chamber from the inlet, and the incident microwave ionizes the atmospheric gas in the reaction chamber to generate plasma, but the plasma density at the inlet is higher than that of the incident microwave. Cutoff density (for example, at a microwave frequency of 2.45 GHz, the plasma density is 7.4 x 10
”/an?), the microwave is reflected at the inlet and does not propagate into the plasma. Here, the pressure in the reaction chamber is 0.
In the range from 1 Torr to several Torr, the mean free path of the atmospheric gas molecules is short and the plasma attenuates quickly, so the plasma inside one reaction chamber has a low density except for the microwave inlet, and the microwave is reflected at the inlet. No consideration was given to the fact that the absorption efficiency into the plasma was low due to the high concentration of oxygen in the reaction chamber, and therefore the activated oxygen concentration in the reaction chamber was not high.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration processing speed or contamination by impurities when there is no plasma damage, and does not take into account plasma damage when processing speed is high. Since there is no resist ashing device that has a high speed, is not damaged by plasma, and is not contaminated by impurities, there is a problem in that plasma processing is performed at the expense of processing speed, resulting in poor productivity.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art as described above, and to provide a plasma processing apparatus that has a high processing speed, is free from contamination by impurities, and is capable of removing resist without being damaged by plasma.

[Means for solving problems]

The configuration of the present invention, which was adopted to solve the above-mentioned problems, includes a microwave power generator, an activation chamber that activates supplied raw material gas to generate plasma, and an activation chamber that activates the supplied raw material gas to generate plasma. In the plasma processing apparatus, the plasma processing apparatus includes a reaction chamber for introducing a converted raw material gas to plasma-process the object to be processed, and a vacuum evacuation device for setting the activation chamber and the reaction chamber to a predetermined pressure. A microwave introduction part having a structure that protrudes into the activation chamber so that the raw material gas introduced into the activation chamber has a large contact area with the microwave; a raw material gas flow path formed between the microwave introduction part that is provided close to the apparatus side and through which the raw material gas flows along the microwave introduction part and an inner wall of the activation chamber; and the activation chamber. The present invention is characterized in that a separation section for separating charged particles in the plasma is provided between the plasma and the reaction chamber.

That is, the present invention uses the activation chamber as a microwave air conditioning resonator having a microwave inlet, so that high-density plasma can be easily generated by supplying microwaves, and the surface area of the microwave inlet is increased. The area where microwaves and plasma come into contact is expanded to improve the efficiency of microwave absorption into plasma, and the area where high-density plasma is generated is expanded to improve the activation concentration of reactive gas. Then, the activated reactive gas is transported onto the object to be treated and reacted with the object by neutral radicals, but in order to enable high-speed processing, the transportation distance is shortened in order to prevent the concentration from decreasing due to transportation. Then, the charged particles in the plasma will also be transported onto the object to be processed, damaging the element.
For example, by installing a charged particle separation section made of a charged particle separation magnet or a metal plate with holes, only highly concentrated neutral radicals of the reactive gas can be transported onto the processing object at high speed without damaging the element. It is now possible to remove the resist.

[Effect]

In this plasma processing apparatus, the activation chamber is a microwave cavity resonator, so the microwaves form a standing wave in the activation chamber, which increases the microwave voltage in the activation chamber, so the activation chamber is activated. The atmospheric gas in the room is ionized and becomes a plasma state. Furthermore, since the activation chamber forms a cavity resonator, microwaves with high energy are stored in the activation chamber, so that the energy given to the generated plasma is also large.

In addition, in the absence of a magnetic field, microwaves supply energy to the plasma, and the density of the plasma increases to 7.4X I Q”/
When it reaches CD, it cannot propagate through the plasma and is reflected by this surface, making it impossible to supply any more energy. Therefore, the area over which microwaves can supply energy to plasma is qualitatively the surface area of the microwave introduction port. Therefore, by increasing the surface area of this microwave inlet, the absorption efficiency of microwaves into the plasma can be improved and high-density plasma (plasma density 7.
The generation area of 4×10”/a7) is expanded, and the amount of plasma in the activation chamber is improved.

The reactive gas (oxygen or a mixed gas of oxygen and carbon tetrafluoride) molecules introduced into the plasma are activated and transported onto the object to be processed along with the flow of vacuum exhaust. However, if the transport distance is shortened so as not to reduce the activation concentration of the reactant gas during transport, the charged particles in the plasma will reach the object to be processed before the end of its life and cause damage to the object.
For example, a magnetic field orthogonal to the transport route is provided on the transport route. This magnetic field traps the electrons in the charged particles and changes the direction of the ions, preventing the charged particles from reaching the object to be processed, preventing element damage, and high-speed processing due to the high concentration of neutral radicals in the reactive gas. will be done.

In addition, instead of the above-mentioned magnetic field, for example, a reactive gas activated by plasma may be transported onto the object to be processed through a metal plate with holes of a predetermined diameter. will flow into the metal plate and will not be transported from this hole onto the workpiece. Therefore, the object to be processed can be processed at high speed with high concentration of neutral radicals of the reactive gas without damaging the element.

FIGS. 2 and 3 show experimental results of the density of plasma generated using microwaves in the absence of a magnetic field.

Figure 2 shows the plasma density from the microwave inlet when a 2.45 GHz microwave was introduced into the generation chamber to generate plasma with 0□ gas at a pressure of Q and 2 Torr. The horizontal and vertical axes respectively represent the distance from the microwave introduction member to the activation chamber wall (the distance between the activation chamber wall and the plasma microwave introduction member at the position of the microwave supply port) (I ) electron density n
o(/aJ) is indicated. The electron density was measured using a Langmuir probe. In this experiment, since ions are considered to be monovalent, electron density = ion density. This electron density is generally called plasma density.

As is clear from Figure 2, the plasma density is 2 x 10"/ad at ioam from the microwave introducing member, but it drops by more than three orders of magnitude to 1 x 107/ad at 100 m. I see. This is it.

The density of plasma in contact with the microwave introduction member is 7.4
X 10''/ad, and since the microwave is reflected here, the plasma away from the microwave introducing member is diffused from here.

This is because the particles disappear due to collisions during this period, and the concentration decreases due to diffusion.

Figure 3 shows the electron density at a distance of 10 mm from the microwave introducing member to 0. It was obtained by changing the gas pressure, and the horizontal and vertical axes show the pressure (Torr) and the electron density n@(
/all), but it can be seen from this figure that as the pressure increases, the density decreases. In other words, even if the pressure is increased by an order of magnitude and the gas molecule concentration is increased by an order of magnitude, the plasma density will decrease by nearly two orders of magnitude at a distance of 10 mm from the introducing member. It can be seen that in order to activate the microwave, it is necessary to pass it right next to the microwave introducing member, and in order to increase this amount, it is essential to increase the area of the microwave introducing member.

Based on these results, in the present invention, the microwave introduction member has a large area with respect to the activation chamber, which is a microwave cavity resonator, and the reactive gas introduced into the activation chamber is The shape of the microwave introduction member was designed to protrude into the activation chamber so that the microwave introduction member always passed through the high-density plasma near the member. Further, the reactive gas was introduced from the side of the activation chamber into which microwaves were introduced.

The distance between the activation chamber and the microwave introduction member should be narrower as the processing pressure is higher.If the pressure is P (Torr) and the distance between the activation chamber and the microwave introduction port is t (Kaku), then t≦ It is necessary to set it as 5ob-.

〔Example〕

Examples will be described below.

Figure 1 is a cross-sectional view of the first embodiment, in which 1 is an activation chamber that forms a cavity resonator for incident microwaves, and has a window 2 for introducing microwaves, and the window 2 maintains a vacuum. made of a material that transmits microwaves, such as quartz or alumina porcelain,
In order to increase the contact area between the raw material gas and the microwave,
A microwave introducing member 3 having a structure that penetrates into the activation chamber 1 is provided, and a supply port 4 for a reactive gas consisting of oxygen or a mixed gas of oxygen and carbon tetrafluoride is provided. There is. Further, at the other end of the activation chamber 1, there is provided a transport path 5 having a size smaller than that for blocking incident microwaves.

6a and 6b are permanent magnets installed outside the transportation path 5; 7 is a yoke; the magnets 6a and 6b cause the transportation path 5 to
Lines of magnetic force 8 are formed perpendicular to the axis of.

Reference numeral 9 denotes a reaction chamber attached to the outlet of the transportation path 5, and its lower flange 10 is provided with a vacuum exhaust port 11 connected to a vacuum exhaust device (not shown). The object to be processed 12 is placed.

Furthermore, in the two windows for introducing microwaves in the activation chamber 1, a connecting waveguide 15 is provided with a tuner 13 and a microwave oscillation source 14 for matching the activation chamber 1 and the incident microwave. is installed.

In such a configuration, a reactive gas (oxygen or a mixed gas of oxygen and carbon tetrafluoride) is supplied from the supply port 4, and a predetermined pressure (0.1 to 10
Evacuate to approximately Torr).

Here, microwaves are oscillated from the microwave oscillation source 14,
Stubs 13a and 13b of the tuner 13.

13c, by matching the applied microwave with the activation chamber 1, the microwave enters the activation chamber 1 through the introducing member 3, forms a standing wave there, and is supplied from the supply port 4 by this electric field. The resulting reactive gas is ionized and turned into a plasma state. Here, the microwave enters into the activation chamber 1 from the entire surface of the protrusion 3a of the introduction member 3 and supplies energy to the plasma of the reactive gas. .4×1
0''/al), which is activated by this plasma, is sent along the flow of vacuum exhaust through the transport path 5 onto the workpiece 12 in the reaction chamber 9.At this time, the activated Magnetic lines of force 8 formed by a pair of magnets 6a and 6b provided on the outer periphery of transport path 5 act on the charged particles in the reactive gas, and the electrons are trapped and transported by the cyclotron motion of magnetic lines of force 8. The ions disappear along the way, and the ions are also changed in direction by the magnetic lines of force 8 and do not reach the object 12 to be processed.

As described above, according to this embodiment, the plasma generation area in the activation chamber can be increased, and the microwave absorption area for the plasma can be expanded to efficiently absorb microwave energy into the plasma. It is possible to create a large volume of high-density plasma in the activation chamber, which creates a highly concentrated activated reaction gas, which remains at a high concentration over a short distance, and the charged particles are separated to generate a neutral reaction. Because only the reactive gas radicals are transported onto the object to be processed, it can be processed at high speed without damaging the device.

FIG. 4 is a longitudinal cross-sectional view of the second embodiment, in which the same parts as in FIG. It shows the part. This embodiment differs from the first embodiment in that instead of installing magnets 6a and 6b on the outer periphery of the transport path, a blow-off part 16 is provided at the outlet of the transport path 5, and the inside of the reaction chamber 9 is The blowout section 16 is configured to be positioned above the object 12 to be processed, and has a large number of small holes 1 on the surface of the blowout section 16 facing the object 12 to be processed.
The blow-off plate 18 provided with 7 is grounded.

In the configuration of this embodiment, similarly to the first embodiment,
The reaction gas is supplied into the activation chamber 1 from the supply port 4, is ionized by microwaves, becomes a plasma state, and forms a large volume of high-density plasma within the activation chamber 1. The highly concentrated reactive gas activated by this plasma is sent onto the object to be processed 12 through the transport path 5 along with the flow of vacuum exhaust.

Here, the transport path 5 is provided with a blow-off section 16, and by setting the dimensions (hole diameter and length) of the large number of small holes 17 of the blow-off plate 18 of this blow-off section 16 to predetermined dimensions, activation can be achieved. Charged particles in the gas do not go into the reaction chamber 9 through this small hole 17. Further, by providing the large number of holes 17 of the blowing plate 18 approximately equal to the unit area of the object to be processed 12, a neutral radical atmosphere of a reactive gas with a uniform and high concentration is created on the object to be processed 12. As described above, according to this embodiment, the charged particles are separated from the activated reactive gas, and the reactive gas is released onto the workpiece at a high concentration over a short distance and at a uniform concentration over the entire surface of the workpiece. Since neutral radicals can be supplied, the resist can be removed uniformly and at high speed without damaging the element.

FIG. 5 is a longitudinal section of the third embodiment, in which the same parts as in FIGS. 1 and 4 are given the same reference numerals, and 1' has a window 2 for introducing microwaves at one end; It shows an activation chamber in which a number of small holes 19 are provided at the other end. This is the first and second
The difference from the embodiment is that the activation chamber 1' does not have the transport section 5 as in the first and second embodiments, and this part forms a part of the activation chamber 1' having the small hole 19. The point is that The dimensions of this small hole J79 are such that microwaves do not pass therethrough and plasma does not exit from this hole. This activation chamber 1' is attached to the reaction chamber 9 such that the surface of the activation chamber 1' having a large number of small holes 19 faces the object 12 to be processed. Here, the structure of the microwave introducing member 3 from the microwave oscillation source 14 and the structure of the inside of the reaction chamber 9 are as shown in FIG. 1 and FIG. 4. This is similar to the second embodiment.

In this configuration as well, similarly to the first embodiment, the microwave forms a standing plate in the activation chamber 1', and ionizes the reactive gas supplied from the supply port 4 to turn it into a plasma state. Here, the microwave introduction member 3 is inserted into the activation chamber 1' through the protrusion 3.
a, the inside of the activation chamber 1' becomes a large-capacity, high-density plasma.

The highly concentrated reactive gas activated by this plasma is sent onto the object to be processed 12 along with the flow of vacuum exhaust through a number of small holes 19 leading to the activation chamber 1'. Here, since the small hole 19 has a size that does not allow the charged particles in the plasma to pass through, only the neutral radicals of the activated reactive gas are sent into the reaction chamber 9, and the small hole 19 is Object to be processed 12
By providing substantially the same amount per unit area of , the neutral radical concentration of the reactive gas sent onto the object 12 to be processed becomes substantially uniform. As described above, according to this embodiment, charged particles are separated from the activated reactive gas using the blowout section having a large number of small holes having the same dimensions as the activation chamber, thereby minimizing the transport resistance over a short distance. Since the resist can be uniformly supplied onto the object to be processed, the resist can be removed uniformly and at high speed without damaging the elements.

The plasma processing apparatus of this embodiment is effective in that it can supply plasma with higher density.

According to these embodiments, the activation chamber for activating the reactive gas and the reaction chamber for treating the object are separate, and the activation chamber forms a cavity resonator for incident microwaves, so the low Plasma is generated stably even in a vacuum region (0.1 to 10 Torr), and the microwave introducing member has a protrusion so that the contact area between the generated plasma and the microwave is large, and the source gas supply port is located in the activation chamber. It is provided close to the side of the micro-microwave power generation device so that the raw material gas is supplied along the microwave introduction part through the raw material gas flow path formed by the microwave introduction part and the inner wall of the activation chamber. Therefore, a large amount of reactive gas plasma with a high density (plasma density: 7.4×10 10 /cd (at a microwave frequency of 2.45 GHz)) is generated along the surface of the protrusion. A reactive gas is supplied into this high-density plasma,
By passing through a high-density plasma over a long distance, the reactive gas is activated to a high concentration. Here, the activated reaction gas is transported to the object to be treated through a transport path, and the charged particles are separated by a magnet or a blow-off section with a large number of small holes so that the charged particles are not transported onto the object to be treated. Therefore, there are no charged particles in the reaction chamber, so there is no damage to the elements on the object to be processed, and there is no problem of foreign matter contamination, such as charged particles colliding with the walls of the reaction chamber and causing reaction chamber materials to adhere to the object to be processed. Moreover, since the transport of activated gas, especially the neutral radicals of reactive gas, from the activation chamber to the reaction chamber takes place over a short distance, the concentration in the activation chamber does not decrease and remains at a high concentration. Since it is carried onto the processing object, high-speed resist ashing processing (resist removal) is possible.

In addition, with a blowout part, by arranging a large number of small holes at predetermined positions, the concentration of neutral radicals of the reactive gas on the object to be processed can be made uniform, and the ashing of the resist can be uniformly achieved. Can be processed.

As described above, according to these embodiments, the resist can be ashed quickly and uniformly without damaging the elements, resulting in improved productivity, stable resist removal,
This has the effect of improving uniformity and yield.

〔Effect of the invention〕

The present invention has a fast processing speed, no contamination by impurities,
This makes it possible to provide a plasma processing apparatus that can remove resist without being damaged by plasma, and has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the plasma processing apparatus of the present invention, and FIG. 2 is a line showing the relationship between the distance from the microwave introducing member to the activation chamber wall and the electron density in the plasma processing apparatus of the present invention. 3 and 3 are diagrams showing the relationship between pressure and electron density, and FIGS. 4 and 5 are sectional views of other different embodiments. 1.1'...Activation chamber, 3...(Microwave) introduction member, 3a...Protrusion part, 4...(Reactive gas)
Supply port, 5... Transportation path, 6a, 6b... Magnet, 9.
... Reaction chamber, 11 ... Vacuum exhaust port, 12 ... Processing object, 13 ... Chu height 1 Figure 13 ... Ryusu trJ -zia a", r also Hayabusa j Hara Dai 2 figure

Claims (1)

[Claims] 1. A microwave power generation device, an activation chamber for activating supplied raw material gas to generate plasma, and introducing the raw material gas activated in the activation chamber to generate plasma. In a plasma processing apparatus having a reaction chamber for plasma-treating a material to be processed, and a vacuum evacuation device for bringing the activation chamber and the reaction chamber to a predetermined pressure, a microwave introduction part having a structure that extends into the activation chamber where the raw material gas and the microwave have a large contact area;
The source gas supply port is provided close to the generator side of the activation chamber, and the source gas flows between the microwave introduction section and an inner wall of the activation chamber, through which the source gas flows along the microwave introduction section. What is claimed is: 1. A plasma processing apparatus characterized in that a source gas flow path formed by the above-described method is provided, and a separation section for separating charged particles in the plasma is located between the activation chamber and the reaction chamber. 2. The plasma processing apparatus according to claim 1, wherein the activation chamber satisfies a microwave cavity resonance condition. 3. The raw material gas flow path has a distance t (mm) between the activation chamber and the microwave introduction part and a pressure p(
3. The plasma processing apparatus according to claim 1 or 2, wherein the plasma processing apparatus has a relationship of t≦50√p with respect to t. 4. Claim 1 or 2, wherein the charged particle separating section in the plasma is constituted by a pair of magnets.
The plasma processing apparatus according to item 1 or 3. 5. A patent in which the part for separating charged particles in the plasma is constituted by a blow-off part that protrudes into the reaction chamber and has a blow-off port having a large number of small holes of a predetermined size at the end thereof. A plasma processing apparatus according to claim 1, 2, or 3. 6. The separating section for charged particles in the plasma is constituted by an end plate provided at an end of the activation chamber and having a large number of small holes of a predetermined size. 2
The plasma processing apparatus according to item 1 or 3.