JPH08190B2 - Fine particle forming method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fine particles which can be used in the field of semiconductor devices for producing capacitors and the like using fine particles and in the industrial field for producing high performance ceramics and the like using sintered bodies. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, in order to generate this kind of fine particles, a thermal CVD apparatus as shown in FIGS. 3 and 4 is applied, an induction plasma CVD apparatus as shown in FIG. 5 is applied, and the like. Has been adopted. In the particle generating apparatus to which the thermal CVD apparatus shown in FIG. 3 is applied, the plate 2 for receiving the generated particles is arranged in the vacuum container 1 and grounded, and the gas nozzle 51 is provided above the plate 2 so as to face it. Further, an exhaust device 4 including an exhaust amount adjusting valve 41 and an exhaust pump 42 is pipe-connected to the container 1, and the gas nozzle 51 is connected to mass flow controllers 521, 522 ,.
, And gas sources 541, 542, ... For producing fine particles, which are connected by piping via open / close valves 531, 532, ..., and a heater 6 for heating is arranged along the wall of the vacuum container 1. In addition, when the substance in the gas sources 541, 542, ... Is a fluid, a heater 7 for heating, if necessary, for vaporizing the substance before supplying it to the container 1 reaches the container from the gas source. It is attached to the pipeline.

The particulate generating apparatus shown in FIG. 4 is obtained by modifying the plate 2 of the apparatus shown in FIG. 3, and is provided with a grounding member 20 in place of the plate 2 shown in FIG. 3, to which a susceptor 201 is attached. A plate S for receiving the generated fine particles is installed. A heater 202 for heating the plate S is built in below the susceptor 201. The other points are the same as those of the apparatus of FIG.

In the particle generating apparatus to which the induction type plasma CVD apparatus shown in FIG. 5 is applied, a plate 2 for receiving the generated particles is arranged in a vacuum container 1 and is grounded.
Above this, a quartz tube chamber 11 is continuously provided in the container 1, a high frequency coil 81 is wound around the quartz tube chamber 11, and a high frequency power source 83 is connected to the coil 81 via a matching box 82. Further, in the quartz tube chamber 11, mass flow controllers 521, 522, ...
32 ... through fine particle generation gas sources 541, 542
... is connected by piping. This pipe is also provided with a heating heater 7 for vaporizing the substance in the gas source, if necessary, when the substance is a liquid. Further, as in the case of the apparatus of FIGS. 3 and 4, an exhaust device 4 including an exhaust amount control valve 41 and an exhaust pump 42 is connected to the container 1 by piping, and a heater 6 for heating is provided along the container wall. It is arranged.

In the fine particle generator shown in FIGS. 3 and 4, sintering is performed.
Silicon nitride (SiN) particles are used as body-forming particles.
Taking the case of formation as an example, the gas source 541 is silane (S
iH _Four) Source or silicon chloride (SiCl_Four) Source,
The gas source 542 is methane gas (CH_Four) Source. Soshi
The valves 531 and 532 are opened and the mass flow
Gas flow rate from them in controllers 521 and 522
Silane gas (or silicon chloride
Gas) together with methane gas from the gas nozzle 51 to the container 1
While being introduced into the interior of the container 1,
The generated gas is maintained at a vacuum level for particle generation and the introduced gas is a heater
It is decomposed by heating at 6 to a high temperature of 1000 ℃ or more.
And the target silicon nitride fine particles are generated.
It These fine particles are deposited on the plate 2 in the apparatus of FIG.
In the device, it falls on the plate S and is received there.
It In addition, in the device of FIG. 4, if necessary, a grounding part
The plate S is heated by the material heater 202.

In particular, in the fine particle generator shown in FIG. 4, it has been attempted to use this to carry out a step of directly attaching fine particles for forming a capacitor or the like on an LSI substrate. In this case, an LSI substrate S is used as the plate S, and a mask is previously formed on the substrate S except the portion where particles are deposited, and fine particles are deposited and deposited on the capacitor formation target portion. Such a process has recently been attempted as part of forming a capacitor having a small area and a large electric capacity, which is required in response to the pattern width of a dynamic RAM becoming narrower.

In the fine particle generator shown in FIG. 5, for example, when silicon carbide (SiC) fine particles are formed as fine particles for forming a sintered body, the gas source 541 is silane (Si).
H ₄ ) source and the gas source 542 is methane gas (CH ₄ ).
As a source, these gases are introduced into the quartz tube chamber 11 at the same time by a predetermined amount under the control of the flow rates by the mass flow controllers 521 and 522 by opening the valves 531 and 532. The inside of the vacuum container 1 and the quartz tube chamber 11 is maintained at a predetermined vacuum degree (about 0.1 to 15 Torr) by the exhaust device 4. The gas introduced into the quartz tube chamber 11 is the high frequency coil 8
1 is supplied with high-frequency power from the power source 83 to be converted into plasma, and silicon carbide (SiC) particles are generated and deposited on the plate 2. Further, in this case, by operating the heater 6, it is possible to form a thermal gradient in the vacuum container and thereby collect the generated fine particles in the plate 2.

[0008]

However, according to the conventional method and apparatus for producing fine particles, the fine particles produced have extremely nonuniform particle diameters, and therefore, when a sintered body is produced using these fine particles, heating is performed. Not to mention pressurization, a large amount of binder was required. In addition, high temperature and high pressure were required for heating and pressing.

Further, even in an attempt to directly form a capacitor or the like on an LSI substrate, a desired capacitor or the like could not be obtained due to the non-uniformity of the particle size of the fine particles adhering to the substrate. Therefore, an object of the present invention is to provide a fine particle forming method and apparatus capable of efficiently forming desired fine particles having a uniform particle diameter, as compared with the conventional fine particle generating method and apparatus.

[0010]

Means for Solving the Problems The present inventor has found the following facts as a result of repeated research for solving the above problems. By applying electric power in a vacuum container and exposing the fine particles generated by turning the fine particle generation gas into plasma, the fine particles are made uniform in size by being introduced into the same inert gas that has been turned into plasma. It is a fact that is done. This is because most of the generated fine particles are negatively charged, while most of the inert gas ions generated by plasma generation by applying electric power are positively charged, and the positive ions of this inert gas are negative. It is presumed that this is because the particles collide with the charged particles and relatively large particles are sputtered, and as a result, the sizes of the particles are made uniform.

The present invention is based on this research, and in order to solve the above-mentioned problems, a gas for producing fine particles is introduced into a vacuum container, plasma is generated by applying electric power under a predetermined vacuum degree, and fine particles are produced. A fine particle generating step for generating
A particle size control step of introducing an inert gas into the vacuum container to turn it into plasma by applying power under a predetermined vacuum degree, and controlling the particle size of the fine particles under the plasma. The present invention provides a method for forming fine particles.

In this method, the step of generating fine particles and the step of controlling particle diameter may be sequentially carried out, or may be alternately repeated if necessary. As the inert gas used for particle size control, in addition to argon gas, helium gas,
Neon gas, krypton gas, xenon gas, etc. are considered. In the method for forming fine particles, further, a gas for forming a fine particle coating film is introduced into the vacuum container, electric power is applied under a predetermined degree of vacuum to generate plasma, and the fine particles are formed under the plasma. A coating step of forming and coating a coating film may be added to form and coat the fine particles with a coating film suitable for the application. This coating step is performed once using one type of coating film forming gas or repeated two or more times, using two or more types of coating film forming gas,
It is conceivable that each is carried out once in an appropriate sequence or repeated two or more times. By this coating step, it is possible to form single-layer coating fine particles, laminated coating fine particles, or gradient composition fine particles whose composition is inclined from the center of the fine particles to the outer surface, which are suitable for the intended use of the fine particles.

It is conceivable to control the magnitude of the applied power in each of the above steps. In that case, in addition to the case where the power is different in each step, when the same power is applied to all steps, the same power is partially applied. There may be cases. Further, in each of the above steps, the power application may be performed in a pulsed manner, but it is conceivable that the power application in all the steps is performed in a pulsed manner, a case in which a part of the power is applied.

Further, it is possible to control the time length of the power application in each of the above-mentioned steps. In that case, in addition to the case where the power application time length is different for each step, the same time length is applied to all the steps. , Part of the same time length may be considered. Further, the fine particle forming apparatus of the present invention for solving the above-mentioned problems, a vacuum container capable of maintaining a predetermined vacuum degree by an exhaust device, a gas supply unit for supplying a gas for generating fine particles to the vacuum container, and fine particles for the vacuum container. It has a gas supply part for supplying an inert gas for controlling the particle size, a means for applying high frequency power to the gas introduced into the vacuum container, and a fine particle receiving part for receiving fine particles generated in the vacuum container. It is characterized by

Also in this apparatus, a gas supply unit for supplying a gas for forming a fine particle coating film to the vacuum container may be included. Further, means for switching and controlling the amount of applied power to the high-frequency power applying means, means for applying pulse modulation to the applied power, time duration of power application, in other words, ON, OFF and ON time, OFF time are set. , Means for controlling, etc. may be included.

In the method and apparatus of the present invention, RF plasma, helicon wave plasma, ECR plasma or the like is adopted as a method and means for applying high frequency power to the fine particle producing gas or the like to generate plasma. Is also good. Further, in the fine particle forming apparatus, it may be considered that the fine particle receiving portion is a semiconductor substrate for which formation of a capacitor or the like is required.

[0017]

According to the method and apparatus for forming fine particles of the present invention, the gas for generating fine particles is introduced into the vacuum container and electric power is applied under a predetermined vacuum degree, and the gas is turned into plasma and fine particles are generated. In addition, an inert gas is introduced into the vacuum container and is similarly turned into plasma. At this time, the particle size is controlled by exposing the particle to the plasma, and the uniformed particle is efficiently formed.

Further, when the step and means for introducing a gas for forming a fine particle coating film into a vacuum container and applying a power to turn the gas into a plasma are added to the method and apparatus for forming fine particles, the use of the fine particles can be improved. A coating film suitable for is formed and coated. Furthermore, when the applied power is controlled in each of the above steps, or the power is applied in a pulsed manner, or the length of time for which the power is applied is controlled, or when a combination of two or more thereof is adopted, the particle size is further controlled. Thus, the uniformed fine particles are efficiently formed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an example of a fine particle forming apparatus according to the present invention. The apparatus shown in FIG. 1 is an apparatus suitable for generating fine particles for producing a sintered body, and is an improvement of the conventional apparatus shown in FIG. In the apparatus shown in FIG. 1, the gas supply unit includes a fine particle generation gas supply unit A, a coating film generation gas supply unit B, and an inert gas supply unit C.
In addition to the high frequency power source 83 in the conventional apparatus shown in FIG. 5, an RF amplifier 84 and an arbitrary waveform generator (function generator) 85 are provided, and these are connected to the matching box 82. The waveform formed by the waveform generator 85 is amplified by the amplifier 84 and supplied to the high frequency coil 81 via the matching box 82. The arbitrary waveform generator 85 can be used to set and control the on / off and on-time of high-frequency power application, the off-time, and the amount of input power.

The gas supply unit A is a mass flow controller 5
21a, a solenoid valve 531a that can be opened and closed at high speed, and a fine particle production gas source 541a (for example, silane) are sequentially connected to the quartz tube chamber 11 by piping. The gas supply unit B includes mass flow controllers 522a, 523a, 524a, high speed opening / closing solenoid valves 532a, 533a, 534a, and a coating film generating gas source 542a (eg, silane), 543a (eg, methane), 544a (eg, ammonia). The quartz tube chamber 11 is sequentially connected and configured. Among the coating film forming gas sources, the same gas source as the fine particle forming gas source may be used as a gas source that also serves as both. The gas supply unit C is a mass flow controller 525a, a high-speed electromagnetic on-off valve 535a, and an inert gas source 545a (for example, argon gas) pipe-connected to the quartz tube chamber 11. Gas sources 541a, 542a, 54
A heater 7 that is operated as necessary is attached to the pipes from 3a and 544a to the quartz tube chamber 11.

Other configurations are the same as those of the conventional device shown in FIG. Next, a specific example of carrying out the method of the present invention by this device,
Amorphous silicon (a-Si) for making sintered bodies
When forming fine particles (example 1), when forming a-Si fine particles coated with a silicon carbide (SiC) film (example 2), and when forming a SiC film and silicon nitride (Si).
The case of forming a-Si fine particles that are laminated and covered with the N) film (Example 3) will be described as an example.

For comparison, the particle size control apparatus of the present invention is used to control a-
The comparative example which formed Si fine particle is shown. 1 in each case
High-frequency power of 3.56MHz is pulse-modulated with a pulse width of 2msec and a duty of 50% (1msec).
ON, 1 msec off) (see FIG. 2). (Comparative Example) The process conditions of the fine particle generation step are as follows.・ Processing vacuum degree: 1.0 Torr ・ Particle generation gas: SiH ₄ 100 ccm ・ RF power: 13.56 MHz, 500 W ・ Modulation frequency: 500 Hz ・ Duty: 50% ・ Power application time (plasma discharge time): 1 min or more conditions When fine particles were generated under the conditions, fine particle generation rate: 1 μm / min, particle diameter: 1 μm ± 0.3 μm, a-Si fine particles were formed, and the particle diameter of the fine particles was ± 30.
% Variation was seen. Example 1 In this example, the particle size control step under the process conditions shown below was performed subsequent to the particle generation step shown in the comparative example, and these steps were sequentially performed once. Pulse modulation was also performed under the same conditions as the comparative example. Deposition vacuum degree: 1.0 Torr Inert gas: Ar 100 ccm RF power: 13.56 MHz, 800 W Modulation frequency: 500 Hz Duty: 50% Power application time (plasma discharge time): 30 sec or more When fine particles were originally formed, a-Si fine particles having a particle diameter of 1 μm ± 0.1 μm were formed, and the variation in particle diameter of the fine particles was ± 10%. It can be seen that the variation is reduced to about 1/3 as compared with the case where the grain size control step is not included.

This is because most of the fine particles formed by turning the fine particle generating gas into plasma by applying electric power are negatively charged, and the positive ions of the inert gas turned into plasma collide with the negatively charged fine particles. However, it is presumed that relatively large particles are easily sputtered, and as a result, the sizes of the particles are made uniform. By repeating the above two steps, it is possible to further control the particle size and efficiently form uniform fine particles.

When a sintered body is produced by using the particles thus homogenized, heating and pressurization do not require high temperature and high pressure, and a small amount of binder is sufficient even if it is unnecessary or required. . Example 2 In this example, in addition to the fine particle generation step and the particle size control step shown in Example 1, the following fine particle coating step (1)
And these were carried out once in sequence.・ Deposition vacuum degree: 1.0 Torr ・ Gas for forming fine particle coating film: SiH ₄ 10
0 ccm CH ₄ 100 ccm ・ RF power: 13.56 MHz, 200 W ・ Modulation frequency: 500 Hz ・ Duty: 50% ・ Power application time: 30 sec When fine particles were formed under the above conditions, the particle size was 1 μm ± 0. 1 μm a-Si fine particles were coated with a 0.1 μm thick SiC film. Example 3 In this example, in addition to the fine particle generation step and the particle size control step shown in Example 1, the fine particle coating step (1) and the fine particle coating step (2) described below are carried out, and step (1) + ( 2) was sequentially repeated 14 times each.・ Deposition vacuum degree: 1.0 Torr ・ Gas for forming fine particle coating film: SiH ₄ 10
0 ccm NH ₃ 100 ccm-RF power: 13.56 MHz, 200 W-Modulation frequency: 500 Hz-Duty: 50% -Power application time: 30 sec When fine particles were formed under the above conditions, the particle size was 1 μm ± 0. 1 μm a-Si fine particles were coated with a 0.1 μm-thick SiC film and a 0.05 μm-thick SiN film, 14 layers each.

The above coated fine particles are variously formed according to the use of the fine particles. In addition to the sintered material shown here, it can be applied to the case of producing beads for preventing laser light reflection.

[0026]

As described above, according to the present invention, as compared with the conventional method and apparatus for forming fine particles, there is provided a method and apparatus for forming fine particles capable of efficiently forming desired fine particles having a uniform particle size. Can be provided. In addition, in the method and apparatus for forming fine particles, when a fine particle coating step is added, it is possible to form coated fine particles suitable for the intended use of the fine particles.

In the fine particle forming method and apparatus, when the applied power is controlled in each step, the power is applied in a pulsed manner, the time length of the power applied is controlled, or a combination thereof is controlled. The particle size is controlled to that extent, and it becomes possible to efficiently form uniform fine particles.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a fine particle forming apparatus which is an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a high frequency power supply pattern according to the present invention.

FIG. 3 is a diagram showing an example of a conventional fine particle forming apparatus.

FIG. 4 is a diagram showing another example of a conventional fine particle forming apparatus.

FIG. 5 is a diagram showing still another example of a conventional fine particle forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vacuum container 11 Quartz tube chamber 2, S Fine particle storage plate 20 Grounding member 201 Susceptor 202 Heater 4 Exhaust device 41 Exhaust amount adjusting valve 42 Exhaust pump 51 Gas nozzle A Fine particle generation gas supply section B Coating film formation gas supply section C Inert gas supply unit 521a, 522a, 523a, 524a, 525a
Mass Flow Controller 531a, 532a, 533a, 534a, 535a
Open / close valve 541a, 542a, 543a, 544a, 545a
Gas source 6, 7 Heater 82 Matching box 83 High frequency power supply 84 High frequency amplifier 85 Arbitrary waveform generator

Claims (10)

[Claims] 1. A fine particle generating step of introducing a fine particle generating gas into a vacuum container to generate plasma by applying electric power under a predetermined degree of vacuum and generating fine particles, and an inert gas in the vacuum container. And a particle size control step of controlling the particle size of the fine particles under the plasma while introducing the plasma into a plasma by applying electric power under a predetermined vacuum degree. 2. A gas for forming a fine particle coating film is introduced into the vacuum vessel to generate plasma by applying electric power under a predetermined vacuum degree, and a coating film is formed and coated on the fine particles under the plasma. The method of forming fine particles according to claim 1, comprising one or more coating steps. 3. The fine particle forming method according to claim 1, wherein the applied power is controlled for each of the steps. 4. The method for forming fine particles according to claim 1, 2 or 3, wherein the power application is performed in a pulsed manner. 5. The method of forming fine particles according to claim 1, wherein the time length of the power application is controlled for each of the steps. 6. A vacuum container capable of maintaining a predetermined degree of vacuum by an exhaust device, a gas supply unit for supplying a gas for producing fine particles to the vacuum container, and an inert gas for controlling the particle size of fine particles to the vacuum container. A fine particle forming apparatus comprising: a gas supply unit for controlling the gas, a unit for applying high-frequency power to the gas introduced into the vacuum container, and a fine particle receiving unit for receiving fine particles generated in the vacuum container. 7. The fine particle forming apparatus according to claim 6, further comprising a gas supply unit that supplies a gas for forming a fine particle coating film to the vacuum container. 8. The fine particle forming apparatus according to claim 6, wherein the means for applying the high frequency power includes means for controlling the applied power. 9. The fine particle forming apparatus according to claim 6, wherein the means for applying the high frequency power includes means for performing the power application in a pulsed manner. 10. The fine particle forming apparatus according to claim 6, wherein the means for applying the high-frequency power includes means for controlling a time length of the power application.