JPH04346653A - Method and device for forming amorphous silicon thin film - Google Patents

Abstract

PURPOSE:To form the amorphous Si thin film on a base body surface at a high speed by casting Si particles from below and a hydrogen ion beam from above to the surface of the base body rotating around a horizontal shaft in a vacuum chamber. CONSTITUTION:The columnar base body 19 rotating around the horizontal axis is arranged in the vacuum chamber 2 segmented by a partition member 22 to an upper chamber 25 and a lower chamber 26 and the inside of the upper and lower chambers 25, 26 is evacuated through a discharge port 3 by a vacuum pump 4 to a vacuum. The Si 5 in the chamber is evaporated by operating an electron beam evaporating source 6 in the lower chamber 26 and the evaporated Si particles 5a are excited by an arc discharge type ionizing means 7, by which the Si particles are brought into collision against the base body 19 and are stuck and deposited onto its surface. This Si deposited surface is admitted into the upper chamber 25 by the rotation around the horizontal shaft, where the surface is irradiated with the hydrogen ion beam 16a from above by the operation of an ion gun 12. The deposited Si particles are brought into reaction with the excited hydrogen and are hydrogenated, by which the thin film of the amorphous Si is efficiently formed at a high speed.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a method and an apparatus for forming a thin film of amorphous silicon, and particularly to a method for forming a thin film of amorphous silicon by hydrogenating silicon deposited on the surface of a substrate. The present invention relates to a method and apparatus for forming an amorphous silicon thin film.

0002

[Prior Art] A thin film of amorphous silicon is usually
It is formed by depositing silicon on the surface of a substrate and hydrogenating the silicon. As a method for forming a thin film of such a compound, plasma C
A VD (chemical vapor deposition) method is known. This method replaces some or most of the thermal energy required for chemical reactions with electrical energy, which has been conventionally used.
This is a thin film forming method that enables thin film formation at a lower temperature than the VD method. In the plasma CVD method, a gas such as silane or hydrogen gas is used as a raw material, and the raw material gas is supplied into a vacuum chamber through a nozzle. Then, by applying direct current or high frequency, glow discharge is caused to generate plasma. Then, the source gas in the chamber is excited by the plasma, causing a chemical reaction. Therefore, a thin film of the compound is formed on the surface of the substrate placed in the plasma. According to such a plasma CVD method, a source gas supplied into a chamber becomes active excited species such as ions, radicals, atoms, or molecules when passing through plasma. Since the reaction of these excited species proceeds even at low temperatures, it is thought that a thin film of the compound is formed on the substrate at low temperatures. Therefore, this plasma CVD method has the advantage of being able to form a uniform film even when the substrate is a three-dimensional object, such as a cylinder, by appropriately setting the nozzle shape. PVD (
It also has the advantages of the physical vapor deposition method.

By the way, when producing amorphous silicon for use in solar cells, photosensitive drums, etc., a high frequency plasma CVD method is usually used among such plasma CVD methods. In addition to being capable of low-temperature film formation as mentioned above, this method also has the following advantages: it is easy to form multiple layers, it is easy to control valence electrons, it is easy to automate continuous operation, and it is easy to increase the area. It has various advantages such as low cost and low cost. However, a major drawback of this high frequency plasma CVD method is that the film formation rate is slow. In the past, research has been conducted to increase the speed of film formation by searching for raw material gases and studying raw material supply methods, but at present the rate of about 10 μm/hr seems to be the limit. As for the cause, some think that it is an essential problem arising from the film formation method.

[0004] For these reasons, high frequency plasma CV
Amorphous silicon film forming methods using methods other than the D method are also being studied. For example, there is a method of forming an amorphous silicon thin film using a PVD method such as a reactive vapor deposition method, a reactive sputtering method, or a reactive ion plating method. Reactive evaporation is a so-called vacuum evaporation method in which raw material silicon is evaporated in a vacuum chamber by resistance heating evaporation or electron beam heating evaporation and deposited on a substrate to form a thin film, and hydrogen gas is introduced at the same time. This is a method for forming a thin film of amorphous silicon. In addition, the reactive sputtering method uses plasma generated in a vacuum chamber to collide high-speed particles with the surface of a silicon target, and the particles that fly out from the target surface due to the sputtering phenomenon are deposited on the substrate. In a so-called sputtering method for forming a thin film, a thin film of amorphous silicon is formed by simultaneously introducing hydrogen gas. The reactive ion plating method is a method in which a part or most of the evaporated silicon particles are excited and ionized in the reactive vacuum deposition method and deposited on a substrate to form an amorphous silicon thin film. However, these PVD methods have drawbacks in common, such as that it may be difficult to control the composition of amorphous silicon and that the film formation rate is relatively slow. for that,
These methods are also practically difficult to apply.

One of the causes of such drawbacks of the PVD method is that hydrogen, which should react with silicon, is not excited. From this point of view, research using IVD (ion assisted vapor deposition) is also being conducted as a method to eliminate this drawback. This method involves exciting a portion or most of hydrogen gas in a reactive vapor deposition method.
The method involves ionizing the material to form an amorphous silicon thin film. Furthermore, by combining such an IVD method with a reactive ion plating method, a part or most of the silicon particles are excited and ionized, and at the same time, a part or most of the hydrogen gas is also excited and ionized, causing them to react. An IAIP (ion assisted ion plating) method has also been proposed in which an amorphous silicon thin film is formed by depositing the amorphous silicon on a substrate (see Japanese Patent Publication No. 63-26557). By using such a method, it is expected that the amorphous silicon thin film will have excellent composition controllability and the possibility of high-speed formation.

By the way, such IVD method or I
When forming an amorphous silicon thin film by the AIP method, solid silicon is used as the raw material silicon, so silicon particles cannot be supplied using a nozzle as in the plasma CVD method. For this purpose, a silicon supply source that supplies raw silicon in the form of particles is installed at the bottom of the vacuum chamber. In that case, conventionally, silicon particles and hydrogen were attached to the substrate at the same time. Therefore, the hydrogen supply source that excites and supplies hydrogen is also arranged at the lower side of the vacuum chamber together with the silicon supply source.

[0007]

However, the present inventors have discovered that such conventional methods and devices have the following problems. That is, in the case of the IVD method, since silicon particles are not excited, it is necessary to increase the evaporation energy of silicon in order to further increase the film formation rate. In order to increase the evaporation energy in this way, it is effective to use an electron beam evaporation source and make the electron beam stronger, but in this case, the hydrogen excitation means is affected and stable operation becomes difficult. will no longer be obtained. In addition, in the case of the IAIP method, it is necessary to provide independent excitation means to excite silicon particles and hydrogen, respectively, but if they are operated simultaneously, they will interfere with each other and their independent operations will not work properly. The problem is that it may not be possible.

[0008] The causes thereof have not yet been completely elucidated at present. However, the following are estimated to be extremely important. That is,
When an electron beam evaporation source is used to evaporate raw material silicon, increasing the power of the electron beam evaporation source generates a large amount of reflected electrons. Furthermore, when silicon particles or hydrogen are excited, excitation or ionization using plasma is usually performed. Since electrons are also generated during ionization, ions and electrons are generated by the excitation. As a result, an extremely large amount of charged particles will be generated within the vacuum chamber. Some of these charged particles reach the substrate and participate in the formation of a thin film, while others exist in the vacuum chamber as stray electrons or stray ions. If such stray charged particles fly into the excitation means, they will have an adverse effect on the excitation means, preventing normal operation. When an electron beam evaporation source for evaporating silicon is placed close to a hydrogen supply source equipped with hydrogen excitation means, stray electrons generated from the evaporation source tend to jump into the hydrogen excitation means. Further, even when the silicon excitation means and the hydrogen excitation means are arranged close to each other, stray charged particles generated from one excitation means tend to fly into the other excitation means. Therefore, in the case where both the silicon supply source and the hydrogen supply source are provided at the lower side of the vacuum chamber as in the conventional case, it is thought that the above-mentioned interference occurs. In order to increase the rate of formation of an amorphous silicon thin film, it is necessary to increase the ionization rate and current density of each excitation means, but if such an attempt is made, the tendency for mutual interference increases.

[0009] In addition, in the case where both the silicon supply source and the hydrogen supply source are arranged at the lower side of the vacuum chamber, it is not only necessary to secure installation space for them at the lower part of the chamber, but also Another problem is that the silicon particles and hydrogen must be guided to the same location on the substrate surface, so their source cannot be brought close to the substrate. If the supply source cannot be brought close to the substrate in this way, it is not possible to further increase the speed of film formation. Furthermore, if the supply source is placed away from the substrate, dead space will be created within the vacuum chamber, resulting in an increase in the size of the entire device.

The present invention has been made in view of the above circumstances, and its purpose is to provide an amorphous silicon film that can speed up film formation, facilitate composition control, and downsize the device. An object of the present invention is to provide a method and apparatus for forming a thin film.

[0011]

[Means for Solving the Problems] In order to achieve this object, in the method for forming an amorphous silicon thin film according to the present invention, a substrate is rotatably supported around a horizontal axis, and silicon particles are supplied from below. After the silicon is attached to the substrate surface, the substrate is rotated, and then excited hydrogen is supplied from above to hydrogenate the silicon attached to the substrate surface. In that case, it is desirable that the inside of the vacuum chamber be electrically isolated on the sides of the base and electrically partitioned into a chamber above and a chamber below the base. Moreover, the upper chamber and the lower chamber can be physically partitioned to make the pressures in each chamber different from each other.

Further, the amorphous silicon thin film forming apparatus according to the present invention is provided with a substrate holder that rotatably supports the substrate around a horizontal axis in the center of the vacuum chamber, and supplies raw material silicon in the form of particles below the substrate holder. A feature is that a silicon supply source is disposed, and a hydrogen supply source that excites and supplies hydrogen is disposed above the silicon supply source. Preferably, a partition member is provided on the side of the base holder,
The inside of the vacuum chamber is divided into upper and lower chambers. In that case, it is desirable that the partition member be made of a conductive material and that a positive or negative potential be applied to the partition member. Further, the pressure in the upper and lower chambers partitioned by the partition member can be individually controlled by evacuation means.

[0013]

[Operation] In this way, after silicon particles are supplied from below the base and adhered to the base surface, when the base is rotated around the horizontal axis, the base surface with the silicon attached faces upward. Become. Therefore, when excited hydrogen is supplied from above, the hydrogen reacts with the silicon on the surface of the substrate, forming a thin film of amorphous silicon. In that case, the silicon source that supplies silicon particles is provided at the bottom of the vacuum chamber, and the hydrogen source that excites and supplies hydrogen is provided at the top of the vacuum chamber, so these sources are located apart from each other. It turns out. Further, even when silicon particles are excited and supplied, the excitation means is provided near the silicon supply source, and therefore is located away from the hydrogen excitation means of the hydrogen supply source. Therefore, even when an electron beam evaporation source is used as a silicon supply source and the silicon particles evaporated from the evaporation source are excited and supplied, stray electrons and stray ions generated from the evaporation source and silicon excitation means are transferred to the hydrogen excitation means. You will be less likely to jump into something. If the inside of the vacuum chamber is physically or electrically partitioned into an upper chamber and a lower chamber, such stray charged particles can be more reliably prevented from jumping into the other excitation means. In this way, mutual interference between the electron beam evaporation source that supplies raw material silicon as evaporated particles, the excitation means that excites the silicon particles, and the hydrogen excitation means is prevented, so that their power can be increased and growth can be achieved. It becomes possible to increase the speed of the membrane.

Furthermore, by arranging the silicon supply source and the hydrogen supply source above and below the vacuum chamber, respectively, their layout becomes easy. Therefore, it is possible to bring the supply source closer to the substrate, and it is possible to further increase the film formation rate and downsize the apparatus. Furthermore, it becomes easy to physically partition the inside of the vacuum chamber into a silicon supply source side and a hydrogen supply source side and create a pressure difference therebetween. Therefore, it becomes possible to use arc discharge type ionization means as the silicon excitation means and glow discharge type ionization means as the hydrogen excitation means, increasing the degree of freedom in these methods of excitation of silicon and hydrogen.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. The figure shows an embodiment of the amorphous silicon thin film forming apparatus according to the present invention, and FIG. 1 is a schematic configuration diagram showing the first embodiment.

As is clear from this figure, this amorphous silicon thin film forming apparatus 1 is equipped with a vacuum chamber 2 in the form of a closed container. The wall surface of the chamber 2 is made of a conductive material such as metal, and is maintained at ground potential. Further, vacuum exhaust ports 3, 3 are provided on the upper and lower sides of the side wall of the chamber 2, respectively, and a vacuum pump 4 as a vacuum evacuation means connected to these exhaust ports 3, 3 reduces the pressure inside the chamber 2. It is now possible to do so.

An electron beam evaporation source 6 is provided at the bottom of the vacuum chamber 2 for evaporating the solid raw material silicon 5 by electron beam heating. Further, above the evaporation source 6, there are particles 5 of silicon 5 evaporated from the evaporation source 6.
An arc discharge type ionization means 7 is provided which excites a by arc discharge. The ionization means 7 consists of a thermionic emission filament 8 and an ionization electrode 9, and depending on the magnitude of the voltage applied from the excitation power sources 10 and 11,
The excited state of the evaporated particles 5a is controlled. In this manner, in this embodiment, the raw silicon 5 is made into particles 5a by the electron beam evaporation source 6 and sent upward from the bottom of the vacuum chamber 2, and the silicon particles 5a are excited and ionized by the arc discharge type ionization means 7. It is now possible to do so. That is, the electron beam evaporation source 6 serves as a silicon supply source, and the arc discharge type ionization means 7 serves as a silicon excitation means.

On the other hand, an ion gun 12 is installed at the top of the vacuum chamber 2 so as to face downward. The ion gun 12 includes a valve 13 and a mass flow controller 1.
A gas introduction pipe 15 having a gas inlet 4 is connected thereto, and hydrogen gas 16 is supplied from the introduction pipe 15. The hydrogen gas 16 is excited and ionized by an excitation power source 17 within the ion gun 12, and is emitted downward from the top of the vacuum chamber 2 as an ion beam 16a. That is, in this embodiment, the ion gun 12 serves as a hydrogen supply source equipped with hydrogen excitation means.

At the center of the vacuum chamber 2, a cylindrical substrate holder 18 is installed horizontally. The holder 18
is detachable from the chamber 2. A cylindrical base 19 is rotatably supported on the outer periphery of the holder 18. The base body 19 is rotated at a constant low speed by an appropriate drive device provided outside the chamber 2. In this way, the base 19
rotates around a horizontal axis in the center of the chamber 2, and is irradiated with a hydrogen ion beam 16a and excited silicon particles 5a from above and below. The base body 19 is, for example, a photosensitive drum for electrophotography, and is made of metal such as aluminum or stainless steel. Then, it is maintained at a negative potential by a DC bias power supply 20 provided outside the vacuum chamber 2. Further, a heater 21 is provided on the outer periphery of the base holder 18, so that the base 19 is heated by the heater 21.

A substantially horizontal partition member 22 is disposed on the side of the substrate holder 18 and extends from the inner surface of the side wall of the chamber 2 to near the outer peripheral surface of the substrate 19 supported by the holder 18 . The partition member 22 is a plate-shaped member made of a conductive material such as metal, and is fixed to the chamber 2 via an insulating material 23. Then, the partition member 22 is provided with a DC power supply 2.
4 is connected, and a positive potential or a negative potential is applied by the power supply 24. In this way, the interior of the vacuum chamber 2 is almost physically partitioned into an upper chamber 25 and a lower chamber 26 by the partition member 22, and the silicon supply source side and the hydrogen supply source side are electrically isolated. ing.

Next, the operation of the amorphous silicon thin film forming apparatus 1 constructed as described above will be explained. When attempting to form a thin film of amorphous silicon on the surface of the cylindrical substrate 19, the substrate 19 is placed in the substrate holder 1.
8 and attach it to the vacuum chamber 2. Then, a vacuum pump 4 is connected to the vacuum exhaust ports 3, 3 of the chamber 2, and the inside of the chamber 2 is evacuated by the vacuum pump 4. At this time, the inside of the chamber 2 is almost partitioned into upper and lower chambers 25 and 26 by a partition member 22 disposed close to the base body 19, and each chamber 25 and 26 is provided with a vacuum exhaust port 3. Therefore, the pressure inside the chamber 2 is uniformly reduced. In addition, the heater 21 is operated to
9 to a predetermined temperature. Furthermore, the partition member 22 includes
A positive potential or a negative potential is applied by the DC power supply 24. Next, the substrate 19 is heated by the DC bias power supply 20.
A predetermined negative bias potential is applied to the substrate 19, and the base 19 is rotationally driven by an external drive device.

In this state, the electron beam evaporation source 6 is operated to evaporate the raw material silicon 5, and the arc discharge type ionization means 7 excites the evaporated particles 5a. Then, at least a portion of the evaporated particles 5a are ionized. The ions are accelerated by the electric field between them and the base 19, collide with the base 19 from below, and are deposited on the surface of the base 19. In this way, a thin film of silicon is formed on the lower surface of the base 19. The silicon thin film is a substrate 1
As 9 rotates, it will eventually move to the upper surface side.

Meanwhile, at the same time, the ion gun 12 is operated to irradiate the base 19 with a hydrogen ion beam 16a from above. Thereby, the excited hydrogen particles collide with the upper surface of the substrate 19. Therefore, the substrate 1
When silicon is attached to the upper surface of 9, the silicon reacts with excited hydrogen and is hydrogenated. That is, it becomes amorphous silicon. In this way, as the base 19 rotates, ion plating of silicon and its hydrogenation are performed continuously, and a thin film of amorphous silicon is formed on the surface of the base 19.

By the way, when the silicon particles 5a are excited in this way, silicon ions and electrons are generated. Further, by excitation of the hydrogen gas 16, its ions and electrons are generated. Moreover, since the raw material silicon 5 is heated and evaporated by the electron beam evaporation source 6, when the electron beam is strengthened, a large amount of reflected electrons are generated. If these charged particles stray and jump into the other excitation means, that excitation means will be disturbed. For example, silicon particles 5
The ions and electrons generated by the excitation of the ion gun 12
If it jumps into the water, the normal operation of the ion gun 12 will be disturbed, and the hydrogen will not be excited to the desired state. Also, an electron beam evaporation source 6 that heats and evaporates the raw material silicon 5
A similar phenomenon occurs when electrons generated from the ion gun 12 jump into the ion gun 12. In this way, when the silicon excitation means and the hydrogen excitation means are operated simultaneously, they may interfere with each other, making it impossible to operate each independently.

However, in the case of this amorphous silicon thin film forming apparatus 1, the raw material silicon 5 is formed into particles 5a.
An electron beam evaporation source 6 and arc discharge type ionization means 7 are installed at the bottom of the vacuum chamber 2, and an ion gun 12 for exciting and supplying hydrogen is installed at the top of the chamber 2. That is, they are located far apart from each other. Therefore, even if the reflected electrons generated from the electron beam evaporation source 6 or the ions and electrons generated by the excitation of the silicon particles 5a stray,
The chances of them jumping into the ion gun 12 will decrease. As a result, mutual interference between the excitation means as described above is reduced. Furthermore, the lower chamber 26 of the vacuum chamber 2 in which the electron beam evaporation source 6 and the arc discharge type ionization means 7 are provided and the upper chamber 25 in which the ion gun 12 is provided are separated by a partition member 22. Provides a physical barrier to stray charged particles. therefore,
Charged particles generated in one chamber 26, 25 are suppressed from moving to the other chamber 25, 26, and
Alternatively, jumping into the excitation means installed in 26 is more reliably prevented.

Further, since the partition member 22 is made of a conductive material and a positive or negative potential is applied to the partition member 22, stray charges generated from the silicon supply source side or the hydrogen supply source side are removed. Migration of the particles to the other source side is also electrically prevented. For example, when a positive potential is applied to the partition member 22, stray electrons are captured by the partition member 22, and stray ions are captured by the partition member 22.
is repelled by Furthermore, when a negative potential is applied to the partition member 22, stray ions are captured by the partition member 22 and stray electrons are repelled. Therefore, the base 1
Even if a relatively large gap is formed between the excitation means 9 and the partition member 22, interference of these stray electrons and ions with the other excitation means is reliably prevented.

[0027] By thus preventing mutual interference between the silicon excitation means and the hydrogen excitation means,
Since it is possible to simultaneously and independently operate them and excite silicon and hydrogen to desired states, it is possible to accurately control the composition of the amorphous silicon thin film that is formed. Furthermore, since the excitation energy can be increased, high-speed film formation is also possible.

Moreover, by supplying the excited silicon particles 5a from below the base 19 and emitting the hydrogen ion beam 16a from above, the electron beam evaporation source 6 and arc discharge type ionization means 7 can be placed in a vacuum chamber. The ion gun 12 may be placed at the top of the chamber 2. Therefore, their arrangement becomes easy in terms of equipment. Since the degree of freedom in their installation positions increases, they can be placed closer to the base 19. In this way, it becomes possible to further increase the film formation rate. Further, by bringing the electron beam evaporation source 6 and the ion gun 12 closer to the base body 19, the vacuum chamber 2 can be made smaller. And, since the dead space in the vacuum chamber 2 is thereby reduced,
The capacity of the vacuum pump 4 etc. can be reduced, and the device 1
The whole can be made compact.

The amorphous silicon thin film forming apparatus 1 was actually manufactured as a prototype, and the following experiments were conducted using it. An aluminum cylindrical substrate 19 having an outer diameter of 100 mm was attached onto the substrate holder 18 . Then, the inside of the vacuum chamber 2 is heated to 1×10-7 Torr by the vacuum pump 4.
The pressure was reduced to r. Further, the temperature of the substrate 19 was set to 400° C. by the heater 21, and a bias potential of −100 V was applied to the substrate 19 by the DC bias power supply 20. On the other hand, a positive potential of 100 V was applied to the partition member 22 by the DC power supply 24. In this state, the base 19 is rotated at 10 rpm.
It was rotated at a low speed. And electron beam evaporation source 6
Then, the arc discharge type ionization means 7 was operated to perform ion plating of silicon. At the same time, hydrogen gas 1
6 was supplied to the ion gun 12, and the ion gun 12 was operated to irradiate the substrate 19 with ionized hydrogen.

As a result, a thin film was formed on the surface of the substrate 19. At this time, the electron beam evaporation source 6 as the silicon supply source, the ionization means 7 as the silicon excitation means, and the ion gun 12 as the hydrogen supply source all operated normally, and no abnormality such as interference was observed. Next, the base 19 on which the thin film was formed on the surface in this manner was taken out from the chamber 2, and an evaluation test was conducted on the thin film. The formed thin film was confirmed to be amorphous by XRD (X-ray diffraction). Further, SIMS confirmed that the hydrogen content in the thin film was 13%. From the results of the film thickness measurement, the film formation rate was calculated to be approximately 20 μm/hr.

[0031] Thus, according to the thin film forming apparatus 1, an amorphous silicon thin film having a constant composition can be formed at high speed.

FIG. 2 is a schematic diagram showing a second embodiment of the amorphous silicon thin film forming apparatus according to the present invention. Note that in the following embodiments, parts corresponding to those in the embodiment of FIG.

This amorphous silicon thin film forming apparatus 3
In the case of No. 1, a glow discharge type ionization means 32 that excites the hydrogen gas 16 by glow discharge is used as the hydrogen excitation means of the hydrogen supply source. On the other hand, silicon particles 5
As the silicon excitation means for exciting a, arc discharge type ionization means 7 is used as in the embodiment of FIG. The upper chamber 25 and lower chamber 26 of the vacuum chamber 2 in which the ionization means 32 and 7 are arranged, respectively, are partitioned by movable partition members 33 and 33 that are supported movably in the horizontal direction by the side walls of the chamber 2. It is being The partition members 33, 33 are moved forward and backward relative to the base 19 supported by the base holder 18 by drive mechanisms 34, 34 provided outside the chamber 2. Further, the vacuum exhaust ports 3, 3 provided in the upper chamber 25 and the lower chamber 26, respectively, are connected to the vacuum pump 4 via variable throttles 35, 35, respectively. The rest of the configuration is similar to the embodiment shown in FIG.

In the amorphous silicon thin film forming apparatus 31 constructed as described above, when an amorphous silicon thin film is to be formed on the surface of the base 19, first, the movable partition members 33, 33 are retracted and the base 19 is The substrate holder 18 with attached is attached to the vacuum chamber 2. Next, the partition member 3 is moved by the drive mechanisms 34, 34.
3, 33 are moved inward and brought close to the outer peripheral surface of the base body 19 to the extent that it does not interfere with the rotation of the base body 19. Thereby, the gap between the base body 19 and the partition member 33 becomes extremely small, and the upper chamber 25 and lower chamber 26 of the chamber 2 become substantially independent. Therefore, the vacuum pump 4 is operated to evacuate the upper chamber 25 and the lower chamber 26. In that case,
The variable throttle 35 on the upper chamber 25 side is sufficiently narrowed, and the throttle 35 on the lower chamber 26 side is kept open. Thereby, the pressure in the lower chamber 26 becomes lower than the pressure in the upper chamber 25. In this way, the upper chamber 2 is
The pressure within the chamber 5 and the pressure within the lower chamber 26 are individually controlled. That is, these variable throttles 35, 35 serve as pressure control means. In this way, the pressure in the upper chamber 25 is relatively high and the pressure in the lower chamber 26 is sufficiently low.
In this state, if the electron beam evaporation source 6 and the arc discharge type ionization means 7 in the lower chamber 26 are operated, and the glow discharge type ionization means 32 in the upper chamber 25 is operated, the silicon particles 5a are excited by the arc discharge. , hydrogen is excited by a glow discharge. The excited silicon particles 5a adhere to the lower surface of the base 19. In addition, the base 19
The top surface of is irradiated with excited hydrogen. Therefore, if the base body 19 is rotated at a low speed, the silicon ion-plated on the bottom side of the base body 19 will be hydrogenated on the top side, as in the case of the embodiment shown in FIG. A thin film of silicon will be formed.

In this way, also in the case of this amorphous silicon thin film forming apparatus 31, the silicon excitation means is provided in the lower part of the vacuum chamber 2, and the hydrogen excitation means is provided in the lower part of the vacuum chamber 2.
installed at the top of the Moreover, there is a partition member 3 between them.
Physically partitioned by 3. Therefore, stray electrons and stray ions generated from these excitation means are prevented from affecting the other excitation means. In that case, as in the embodiment of FIG. 1, the partition member 33 may be made of a conductive material and a positive or negative potential may be applied to the partition member 33. In this way, the upper chamber 25 where the hydrogen excitation means is provided and the lower chamber 26 where the silicon excitation means is provided are electrically separated, thereby more reliably preventing mutual interference between these excitation means. be done.

By making the partition member 33 movable in the horizontal direction as described above, the base 1 having different outer diameters can be
9, the gap between the partition member 33 and the base body 19 can be made sufficiently small. Therefore, the pressure in the upper chamber 25 and the lower chamber 26 of the vacuum chamber 2 can be made different, and the arc discharge type ionization means 7 and the glow discharge type ionization means 32 can be used as silicon and hydrogen excitation means, respectively. Those based on different principles can be used. That is, the degree of freedom in selecting the excitation means increases. As a result, it becomes possible to adopt the most suitable excitation means according to the required conditions of the amorphous silicon thin film, and it is possible to improve the composition accuracy of the resulting amorphous silicon thin film and further accelerate the film formation rate. becomes.

FIG. 3 is a schematic diagram showing a third embodiment of an amorphous silicon thin film forming apparatus according to the present invention. As is clear from this figure, this amorphous silicon thin film forming apparatus 41 is designed to form an amorphous silicon thin film on a flat base 42. In the thin film forming apparatus 41, a thick plate-shaped substrate holder 43 is used. The substrate holder 43 is rotatably supported by the vacuum chamber 2 around a horizontal axis. A rotary drive device (not shown) provided outside the chamber 2 rotates the chamber 2 by 180 degrees at regular time intervals. Two flat substrates 42, 42 are detachably attached to both surfaces of the substrate holder 43, respectively. Further, a heater 44 is provided at the intermediate portion of the substrate holder 43, and the substrates 42, 42 are heated by the heater 44. Further, a negative potential is applied to the substrates 42, 42 from outside the chamber 2 by a DC bias power source (not shown). The rest of the configuration is similar to the embodiment shown in FIG.

In the amorphous silicon thin film forming apparatus 41 constructed as described above, when the electron beam evaporation source 6 and the arc discharge type ionization means 7 are operated with the substrate holder 43 in a horizontal state, the raw material silicon 5 is evaporated and its The evaporated particles 5a are excited, and the particles 5a adhere and deposit on the surface of the substrate 42 mounted on the lower surface side of the substrate holder 43. Then, when the substrate holder 43 is rotated 180 degrees after a certain period of time has elapsed, the substrate 42 on which the silicon thin film is formed moves to the upper surface side of the substrate holder 43. Therefore, the ion gun 12 installed at the top of the vacuum chamber 2 produces a hydrogen ion beam 16a.
When irradiated from above, the silicon on the surface of the base 42 is hydrogenated and becomes amorphous silicon. In this way, when the substrate holder 43 is rotated a predetermined number of times, an amorphous silicon film of a predetermined thickness is formed on the two substrates 42, .

In this case as well, stray electrons and stray ions generated from the electron beam evaporation source 6 and the arc discharge type ionization means 7 are prevented from jumping into the ion gun 12, as in the case of the embodiment shown in FIG. It is. If shutters are provided on the silicon supply side and the hydrogen supply side to respectively block the silicon particles 5a and the hydrogen ion beam 16a while the substrate holder 43 is rotating, mutual interference between these excitation means can be more reliably prevented. Prevented.

In the above embodiment, the silicon particles 5a are excited and supplied by the arc discharge type ionization means 7, but the present invention is also applicable to cases where such a silicon excitation means is not used. can do. For example, by increasing the power of the electron beam evaporation source 6, the evaporated silicon particles 5a are directly transferred to the substrate 19 or 4.
2, the configuration described above prevents reflected electrons generated from the evaporation source 6 from interfering with the hydrogen excitation means.

Furthermore, the silicon particles 5a can be supplied not only by the electron beam evaporation source 6 as in the above embodiment but also by a resistance heating evaporation source, sputtering, or the like. When the silicon particles 5a are excited and ionized, glow discharge, thermionic radiation, or the like can be used as the excitation means. Furthermore, a combination of a plurality of them may be used. For hydrogen excitation,
At least one of glow discharge, arc discharge, thermionic radiation, and ion gun can be used.

[0042] When providing the partition member 22 or 33,
They may be arranged in several layers. In addition, if the partition member is used only for electrical shielding,
It can also be made into a mesh shape or the like. In this way, the upper chamber 25 and the lower chamber 26 of the vacuum chamber 2 are physically connected, so in the case of the embodiment shown in FIG. 1 or 3, the vacuum exhaust port 3 of the chamber 2 is It can be a single one.

[0043]

[Effects of the Invention] As is clear from the above explanation, according to the present invention, while rotating the base body around the horizontal axis,
Since silicon particles are supplied from below the base and excited hydrogen is supplied from above, the adhesion of silicon particles and their hydrogenation occur continuously, and amorphous silicon is deposited on the surface of the base. A thin film of can be formed. By doing so, the silicon supply side and the hydrogen supply side can be placed apart from each other, so that mutual interference due to stray electrons and stray ions can be prevented. Therefore, it becomes possible to accurately control the composition of the amorphous silicon thin film. Further, since the power of the silicon particle supply source, its excitation means, or hydrogen excitation means can be increased, the film formation rate can be increased. Furthermore,
The silicon source is now located at the bottom of the vacuum chamber and the hydrogen source at the top of the vacuum chamber, allowing them to be closer to the substrate. Therefore, the film formation rate can be further increased. Moreover, since the dead space within the vacuum chamber is thereby reduced, the entire apparatus can be made more compact. Moreover, it becomes easy to apply a differential pressure between the silicon supply side and the hydrogen supply side. By doing so, the silicon excitation means and the hydrogen excitation means can be of different types, thereby increasing the degree of freedom in selecting these excitation means. Therefore, it becomes possible to improve the efficiency of forming an amorphous silicon thin film.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of an amorphous silicon thin film forming apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing another embodiment of the amorphous silicon thin film forming apparatus according to the present invention.

FIG. 3 is a schematic configuration diagram showing still another embodiment of the amorphous silicon thin film forming apparatus according to the present invention.

[Explanation of symbols]

1 Amorphous silicon thin film forming apparatus 2 Vacuum chamber 4 Vacuum pump (vacuum evacuation means) 5 Raw material silicon
5a Silicon particles 6 Electron beam evaporation source (silicon supply source) 7 Arc discharge type ionization means (silicon excitation means) 12 Ion gun (hydrogen excitation means) 16 Hydrogen gas
16a Hydrogen ion beam 18 Substrate holder 19 Substrate 22 Partition member 24 DC power supply 25 Upper chamber 26 Lower chamber 31 Amorphous silicon thin film forming device 32 Glow discharge type ionization means (hydrogen excitation means) 33 Movable partition member 34 Drive mechanism 35 Variable aperture ( Pressure control means) 41 Amorphous silicon thin film forming device 42 Flat substrate 43 Substrate holder

Claims (8)

[Claims] Claim 1: A substrate is rotatably supported around a horizontal axis in a vacuum chamber, and silicon particles are supplied from below the substrate and attached to the surface of the substrate, and then
A method for forming an amorphous silicon thin film, characterized in that the silicon attached to the surface of the substrate is hydrogenated by rotating the substrate and supplying excited hydrogen from above. 2. The inside of the vacuum chamber is electrically partitioned into a chamber above the base body and a chamber below the base body, and the silicon particles are excited and supplied. The method for forming the amorphous silicon thin film described above. 3. The inside of the vacuum chamber is physically partitioned into a chamber above and below the substrate, and the upper and lower chambers are set at different pressures to excite the silicon particles and hydrogen using different excitation methods. characterized by causing
A method for forming an amorphous silicon thin film according to claim 1 or 2. 4. A vacuum chamber whose interior is depressurized by evacuation means, a substrate holder provided at the center of the vacuum chamber and supporting the substrate rotatably about a horizontal axis, and a substrate holder provided at the bottom of the vacuum chamber. a silicon supply source that is provided and supplies raw material silicon in the form of particles upward; and a hydrogen supply source that is provided above the vacuum chamber and excites hydrogen gas and supplies it downward; Amorphous silicon thin film forming equipment. 5. The amorphous silicon thin film forming apparatus according to claim 4, further comprising a partition member provided on a side of the substrate holder to partition the inside of the vacuum chamber into an upper chamber and a lower chamber. 6. The amorphous silicon thin film forming apparatus according to claim 5, wherein the partition member is made of a conductive material, and a DC power source is provided for applying a potential to the partition member. 7. The evacuation means includes pressure control means for individually controlling pressures in upper and lower chambers partitioned by the partition member, and the silicon particles supplied from the silicon supply source 7. The amorphous silicon thin film forming apparatus according to claim 5, wherein the amorphous silicon thin film is excited by a different type of excitation means from the hydrogen excitation means used in the supply source. 8. The amorphous silicon thin film forming apparatus according to claim 7, wherein the partition member is movable in a horizontal direction.