JP2002217111A - Plasma film forming apparatus and film forming method using the same - Google Patents

Abstract

(57) Abstract: A plasma film forming apparatus for forming a film with high uniformity on a film forming substrate having a relatively large area is provided. An electrode substrate (3) on which electrodes (2) are arranged is installed in a vacuum vessel (5). A large number of electrodes 2 are arranged on the electrode substrate 3 in a stripe shape. The film formation substrate 4 is held by the holder 8 at a position facing the electrode 2. A gas supply unit 13 for supplying a material gas is provided. Electrode 2a (cathode electrode) to which voltage is applied by power supply unit 1
Between them, three electrodes 2b (anode electrodes) at the ground potential are arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma film forming apparatus and a film forming method using the same, and more particularly, to a plasma film forming apparatus used for forming an amorphous silicon film or an insulating film widely used in the electronic industry. A membrane device;
The present invention relates to a film forming method using the same.

[0002]

2. Description of the Related Art When manufacturing electronic devices such as integrated circuits, liquid crystal displays, and amorphous solar cells, a predetermined semiconductor film or the like is formed using plasma. A method of forming a film using plasma is called a plasma-excited chemical vapor deposition (Chemical Vapor Deposition) method. Since this method is simple and excellent in operability, it is widely applied to the manufacture of various electronic devices.

An example of a plasma film forming apparatus for performing such plasma enhanced chemical vapor deposition will be described.
As shown in FIGS. 12 and 13, a closed space is formed by the vacuum vessel 105. In the vacuum vessel 105,
Electrodes 102a and 102b composed of two opposing conductive plates electrically insulated from each other are arranged. Plasma is generated between the two electrodes 102a and 102b, and the material gas is dissociated by introducing the material gas from the gas supply unit 113 into the plasma atmosphere. When the material gas is dissociated, the deposition substrate 1 attached to one of the electrodes 102a is formed.
A semiconductor film or the like is formed on the surface of the substrate 04.

A high frequency power 101 is used to generate plasma. The frequency of the high frequency power 101 is usually 13.56 MHz. Two opposing electrodes 10
By setting one of the electrodes 2a and 102b to the ground potential and applying a high frequency voltage to the other electrode, the two electrodes 1
A high-frequency electric field is generated between 02a and 102b. And
A breakdown phenomenon occurs due to a high-frequency electric field, and plasma is generated as a glow discharge phenomenon.

[0005] An electrode to which a high-frequency voltage is applied, that is, an electrode that supplies electric energy, is called a cathode electrode or a discharge electrode. Since a large electric field is formed near the cathode electrode, electrons in the plasma accelerated there promote the dissociation of the material gas to generate radicals.

A region where a large electric field is formed near the cathode electrode in the discharge region 111 is called a cathode sheath portion. The radicals generated in the cathode sheath part diffuse to the film formation substrate 104 fixed to the upper electrode 102a, so that a film grows on the surface of the film formation substrate 104.

[0007] Such a plasma film forming apparatus is widely used in various industries. For example, in a manufacturing process of an active drive type liquid crystal display, T
A switching element called an FT (Thin Film Transistor) is formed. In a TFT, a gate insulating film such as an amorphous silicon film (a-Si film) or a silicon nitride film plays an important role as a component thereof.
In order for these films to play a predetermined role, a technology capable of uniformly forming a high-quality film on the substrate surface is indispensable.

For this reason, various proposals have been made for the plasma CVD method in accordance with recent advances in plasma engineering and semiconductor engineering. For example, in the literature (J.Vac.Sci.Techno
l.A10 (1992) 1080A.A.Howling) proposes a method for improving the film forming speed of a semiconductor device by shifting the high frequency from 13.56 MHz to a higher frequency VHF band.

However, in the case of manufacturing a liquid crystal display, an amorphous solar cell, or the like, a considerably large substrate having a size of about several tens of cm to about 1 m is required as a film formation substrate. In the case of a deposition substrate having such a relatively large area, it is difficult to uniformly deposit a high-quality film.

The reason is that the film forming substrate 104 is formed on the ground electrode. That is, the electrode 102
When plasma is generated between a and 102b, a potential difference called a sheath voltage is generated on the surface of the deposition substrate 104 on the ground electrode. Such a potential difference cannot be basically avoided as long as plasma is present. The sheath voltage accelerates ions in the plasma, and as a result, the surface of the thin film formed on the surface of the deposition substrate 104 is damaged by the ions, and the film quality is degraded.

As a method for forming a high-quality film on the film forming substrate 104 to solve such a problem, there is a method disclosed in Japanese Patent Application Laid-Open No. H11-144892, for example. In this publication, a high quality electrode is provided by providing a plurality of electrodes having a corrugated surface, forming a film-forming substrate at a position separated from the electrode and forming a horizontal electric field (substantially parallel to the film-forming substrate surface). A method for forming a film is disclosed.

In particular, in this method, by disposing the film-forming substrate at a position away from the electrode, the film-forming substrate is not exposed to the plasma, and deterioration due to ion bombardment on the surface of the thin film is suppressed. Thereby, deterioration of the film quality is suppressed, and a high-quality film is formed.

[0013]

However, the method described in JP-A-11-144892 has the following problems. As described above, a plurality of electrodes having a wavy uneven surface are provided, but when each electrode is arranged so that the interval between adjacent electrodes is several mm to several tens of mm, the cathode sheath portion is It appears repeatedly at twice the length of the electrode interval, and the region where radicals are generated is unevenly present on the surface of the film formation substrate.

Therefore, in order to form a uniform film,
The deposition substrate must be located at a considerable distance from the electrode so that the non-uniformity of the region where the radical is generated is reduced by the diffusion of the radical.

However, the radicals disappear in accordance with the diffusion distance in the process of diffusion, so that there is a problem that a sufficient film formation rate cannot be obtained if the film formation substrate is far from the electrodes.

Further, since a discharge occurs only between adjacent electrodes, the pressure range in which the plasma film forming apparatus can operate is limited due to a restriction on discharge physical theory called Paschen characteristics. When the pressure is too low, the probability that electrons collide with the material gas between the electrodes is reduced and the plasma is not generated when the pressure is too low.On the other hand, when the pressure is too high, the electrons collide with the material gas and the energy is excessively increased. It refers to a phenomenon in which the plasma is lost, the electrode cannot be reached, and the plasma cannot be maintained. Due to such restrictions, once the distance between the electrodes is determined, the region where plasma can be generated is limited, and only limited film forming conditions can be realized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and one object of the present invention is to provide a plasma film forming method capable of uniformly forming a high quality film on a film forming substrate having a relatively large area. Another object is to provide an apparatus, and to provide a thin film forming method using such a plasma film forming apparatus.

[0018]

According to one aspect of the present invention, a plasma film forming apparatus includes a processing chamber, a material gas inlet, and an electrode. The material gas inlet introduces a material gas into the processing chamber. The electrode includes a cathode electrode and an anode electrode, and a surface of a substrate on which a radical generation region of a material gas formed based on a discharge path generated between the cathode electrode and the anode electrode is introduced into a processing chamber and processed. And / or causing a discharge path whose length along the surface of the substrate is longer than the distance between adjacent electrodes.

According to this plasma film forming apparatus, at least one of the time-dependent movement of the radical generation region along the substrate surface and the formation of a discharge path longer than the distance between adjacent electrodes is performed. Thus, the radical generation region extends along the surface of the substrate. This allows
The distribution of the radical generation region becomes more uniform, and a film with high uniformity can be formed in the substrate surface.

In order to form a discharge path longer than the interval between adjacent electrodes, specifically, a plurality of anode electrodes and cathode electrodes are respectively disposed so as to face the substrate and to be substantially parallel to the substrate. Preferably, at least two anode electrodes are arranged between the electrodes.

In this case, a discharge path is formed between the cathode electrode and the anode electrode located immediately adjacent to the cathode electrode by skipping one anode electrode.

Preferably, in the cathode electrode and the anode electrode, the respective positions of the cathode electrode and the anode electrode change with time while maintaining the relative positional relationship between the cathode electrode and the anode electrode.

In this case, the radical generating region at a certain time and the radical generating region at the next time overlap each other, and the distribution of the radical generating region becomes more uniform when averaged over time. A film with higher uniformity can be formed.

More preferably, the moving distance per change in the temporal position of the cathode electrode and the anode electrode is shorter than the length of the discharge path longer than that between adjacent electrodes.

In this case, the radical generation region at a certain time and the radical generation region at the next time can be surely overlapped with each other in the change in the temporal position of the cathode electrode and the anode electrode.

Preferably, the cathode electrode and the anode electrode are alternately arranged, and their positions alternate with time.

In this case as well, a film having higher uniformity can be formed on the substrate surface as in the above case.

A film forming method according to another aspect of the present invention is a film forming method for forming a predetermined film on a substrate by introducing a material gas into a processing chamber in which a cathode electrode and an anode electrode are arranged. Moving the radical generation region of the material gas formed based on the discharge path generated between the cathode electrode and the anode electrode temporally along the surface of the substrate; The method includes a film forming step of forming a predetermined film on the substrate by performing at least one of generating a discharge path longer than a matching electrode interval.

According to this film forming method, the radical generation region is moved temporally along the substrate surface and / or a discharge path longer than the interval between adjacent electrodes is formed. Therefore, the radical generation region extends along the surface of the substrate. Thereby, the distribution of the radical generation region becomes more uniform, and a film with high uniformity can be formed in the substrate surface.

Preferably, a plurality of anode electrodes and a plurality of cathode electrodes are arranged so as to face the substrate and to be substantially parallel to the substrate, and at least two anode electrodes are arranged between adjacent cathode electrodes. .

In this case, a discharge path is formed between the cathode electrode and the anode electrode located immediately adjacent to the cathode electrode by skipping one, thereby forming radicals. The region extends along the surface of the substrate, so that a highly uniform film can be formed.

As described above, in order to form a longer discharge path, in the film forming step, a discharge voltage for starting discharge between the cathode electrode and the anode electrode is at least generated between the cathode electrode and the anode electrode. Preferably, a firing voltage corresponding to a longer discharge path of the two firing paths is set, such a firing voltage corresponding to a lower pressure value in the pressure dependence of the firing voltage. It is.

Preferably, in the film forming step, the respective positions of the cathode electrode and the anode electrode are temporally changed while maintaining the relative positional relationship between the cathode electrode and the anode electrode.

In this case, the radical generation region at a certain time and the radical generation region at the next time overlap with each other, and the distribution of the radical generation region becomes more uniform when the time is averaged. A film with higher uniformity can be formed.

More preferably, in the film forming step, the moving distance per change in the temporal position of the cathode electrode and the anode electrode is shorter than the length of the discharge path longer than that between adjacent electrodes.

In this case, the radical generation region at a certain time and the radical generation region at the next time can be surely overlapped with each other in the change in the temporal position of the cathode electrode and the anode electrode.

Preferably, the cathode electrode and the anode electrode are alternately arranged, and in the film forming step, the positions of the cathode electrode and the anode electrode are alternately changed with time.

In this case as well, a film with higher uniformity can be formed on the substrate surface as in the above case.

Next, the function and effect of the present invention will be described more specifically. First, the inventors generated plasma using the plasma film forming apparatus shown in FIGS. 1 and 2 to form an amorphous silicon film. At this time, SiH ₄ (flow rate 1 L / min (1000 scc)
m)), H ₂ (flow rate ₂ L / min (2000 scc)
m)) was used. In addition, for example, Ar (argon), O ₂ (oxygen), N ₂ (nitrogen), N ₂
H ₃ (ammonia) or a mixed gas thereof may be added to the source gas. Then, a material gas was supplied from gas introduction holes 6 located between the electrodes 2 arranged in a stripe shape.

The striped electrode 2 is made of a dielectric (glass)
It is arranged on an electrode substrate 3 made of a plate. For example,
The size of the electrode substrate 3 was 1 m × 1 m, and the size of one electrode 2 was 950 mm × 2.5 mm × 100 μm (depth D × width W × thickness H). The distance between adjacent electrodes 2 was 5 mm.

It should be noted that such a striped electrode 2
Can be extremely easily formed on the electrode substrate 3 by a pattern printing method. Alternatively, stainless steel or aluminum may be cut into a rod shape to form an electrode, and an insulator such as Teflon (registered trademark) or photoveil may be used as the electrode substrate.

Then, a high frequency of 100 kHz was applied to the electrode 2. At this time, a temporally continuous application mode was adopted. Further, as shown in FIG. 2 in particular, three electrodes 2b (anode electrodes) at the ground potential were arranged between the electrodes 2a (cathode electrodes) to which a voltage was applied (pattern 1).

The pressure dependence of the discharge starting voltage in this case was evaluated. For comparison, the same evaluation was performed for the case of the same electrode arrangement (pattern 2) as that disclosed in JP-A-11-144892. The result is shown in FIG. As shown in FIG. 5, it was found that the pattern 1 can generate plasma even on the lower pressure side than the pattern 2 can.

This is considered as follows. First, a discharge path is formed between the cathode electrode and the anode electrode. In the case of pattern 2, the distance between electrodes at which such a discharge path is formed has only one value. In the case of pattern 1, there are two values as such distance between electrodes.

That is, as shown in FIG. 2 or FIG. 4, in the case of pattern 1, the distance between the cathode electrode 2a shown in the discharge path 11b and the anode electrode 2b located immediately next to the discharge path 11b, Cathode electrode 2a shown
It is considered that there are two values, namely, the distance between the anode electrode 2b located one anode electrode 2b adjacent to the anode electrode 2b, and the pressure range in which plasma can be generated is widened.

As shown in FIG. 5, in the case of pattern 1, the discharge based on the discharge path 11b becomes dominant in the high pressure area (near the operating point B), and the discharge path 11a in the low pressure area (near the operating point A). Is considered to be dominant.

As described above, it has been found that, by expanding the range of the pressure at which the plasma can be generated, it is possible to form a film of a different film type by the plasma film forming apparatus.

Although the numerical values on the vertical and horizontal axes are not shown in FIG. 5, the numerical values differ depending on the type of gas used. For example, as an example, SiH ₄ and H ₂
When the mixed gas with the above is used as the material gas, the pressure at the operating point A is about 40 Pa, and the discharge starting voltage in that case is-
It was 520V. The pressure at the operating point B is about 80 Pa
In this case, the discharge starting voltage was -450V. That is, the minimum value of the absolute value of the discharge starting voltage is 450 V
It became.

Next, a case where an amorphous silicon film is formed will be described. The electrode substrate 3 as the film forming substrate 4
A glass substrate having a thickness of 1.9 mm was placed at a position 15 mm away from the glass substrate. 7, the electrodes 2a (cathode electrodes) to which a voltage is applied and the electrodes 2b (anode electrodes) at the ground potential were alternately arranged as shown in FIG. Further, as a voltage application form, the cathode electrode 2a
And the anode electrode 2b were formed in a pattern (pattern 3) of alternately changing over time. In terms of time, the pulse width is 10
The pulsed application of μsec was performed alternately. For comparison, the film-forming substrate 4 was similarly formed for the pattern 2 as well.
An amorphous silicon film was formed thereon.

When the film thickness distribution of the amorphous silicon film formed on the film-forming substrate 4 was evaluated, in the case of the pattern 2, the film thickness uniformity was ± 30%, indicating that the film could not be used for an actual device. all right. On the other hand, in the case of pattern 3, the film thickness uniformity was ± 9%, which was a level that can be used for an actual device.

The reason why the film thickness uniformity is improved as described above is considered as follows. As shown in FIGS. 6A to 6D, in the case of pattern 2, since the position of the cathode electrode does not change with time, even if the time is averaged, as shown in FIG. Also, the cathode sheath portion that generates radicals is formed at a fixed position.

For this reason, the distribution of the amount of radicals that diffuse from the radical generating section (generating region) and reach the deposition substrate becomes non-uniform, reflecting the non-uniformity of the radical generating section, and as a result, the film thickness distribution becomes uneven. It is considered to be uniform.

On the other hand, in the case of pattern 3, FIG.
Since the positions of the cathode electrode and the anode electrode change with time as shown in FIG. 7D, the distribution of radical generation is almost uniform when time-averaged as shown in FIG. 7E. . It is considered that this improves the uniformity of the film thickness distribution on the film formation substrate.

Next, the same evaluation was performed for the pattern (pattern 4) shown in FIG. 9 as an application mode for applying a voltage to the electrode. The pattern 4 will be described. As for the arrangement of the electrodes 2, three electrodes 2b (anode electrodes) at the ground potential were arranged between the electrodes 2a (cathode electrodes) to which a voltage was applied. Further, as a voltage application mode, respective positions were temporally changed while maintaining a relative arrangement relationship between the cathode electrode 2a and the anode electrode 2b. In terms of time, a pulse-like application with a pulse width of 10 μsec is sequentially performed. That is, the pattern 1 is a pattern that is temporally changed.

When the film thickness distribution of the amorphous silicon film formed on the film formation substrate was evaluated based on the pattern 4, the film thickness uniformity was improved to ± 5%. It is considered that the film thickness uniformity is further improved as described below.
Since pattern 4 has the components of pattern 1, FIG.
As shown in (2), there are two discharge paths 11, a discharge path 11a and a discharge path 11b. Thereby, the radical generating portion has a distribution centered on the position of the cathode electrode.

The pattern 4 is a pattern obtained by changing the pattern 1 over time. For this reason, FIGS.
As shown in FIG. 9D, the distribution of the radical generating portions changes with time. As a result, as shown in FIG. 9E, it is considered that the radical generation unit becomes uniform when the time is averaged, and the uniformity of the film thickness formed on the film formation substrate is improved.

As described above, the discharge path 11 between the cathode electrode 2a and the anode electrode 2b adjacent to the cathode electrode 2a is skipped by one.
In order to exhibit the effect of the discharge based on a and the effect of maintaining the relative positional relationship between the cathode electrode 2a and the anode electrode 2b and changing the position of each electrode with time, at a certain time, It is effective that the horizontal discharge path is longer than the interval between the electrodes serving as the cathode electrodes 2a.

As the discharge path becomes longer, the radical generating portion expands in the horizontal direction. Since the horizontal discharge path is longer than the interval between the cathode electrodes 2a, the radical generator generated at one time overlaps the radical generator generated at the next time, and the time average is Thus, the radical generating section is made uniform.

The length of the discharge path depends on the pressure.
That is, in the case of the discharge path 11b shown in FIG. 4 (pattern 2), as shown in FIG. 5, there is one local minimum value of the discharge start voltage as the pressure dependency of the voltage. On the other hand, when the discharge path 11a shown in FIG. 4 is included in addition to the discharge path 11b (pattern 1), it was newly found that there are two minimum values of the discharge starting voltage as shown in FIG.

In the vicinity of the minimum value of the discharge voltage on the low pressure side shown in FIG. 5 (operating point a), the two discharge paths 11a and 11
The discharge path 11a out of b becomes dominant. By setting the pressure of the plasma film forming apparatus near this pressure, the time-averaged radical generating unit is formed over a wider range as shown in FIG. 10, and is formed on the film forming substrate. Thus, the uniformity of the film thickness is further improved. Also, by setting the discharge voltage near the minimum value of the discharge voltage on the high pressure side (operating point b) near the pressure, the time-averaged radical generation unit is made uniform as shown in FIG.

As a method of supplying electric energy for generating plasma, various forms such as DC voltage application, DC pulse voltage application, AC voltage application, AC pulse application, high frequency application or high frequency pulse application can be adopted. . The frequency band of the alternating current is 60 to several hundred kHz, and the frequency band of the high frequency is several hundred kHz to several tens MHz. The pulse application is preferably applied to a pattern (patterns 3 and 4) that changes the position of the electrode with time. Depending on the method of supplying the electric energy, the distribution of the generated amount of the radical generating unit may slightly change, but there is essentially no change.

In the above description, the case where an amorphous silicon film is formed has been described as an example. However, the present invention can be applied to the case where a silicon nitride film or a silicon oxide film is formed by changing a material gas. As in the case of the amorphous silicon film, it was found that a high quality film can be uniformly formed on the film formation substrate.

[0063]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A description will be given of a plasma film forming apparatus according to Embodiment 1 of the present invention and pressure dependency of a discharge starting voltage in the plasma film forming apparatus.

First, a plasma film forming apparatus will be described. As shown in FIGS. 1 and 2, in a plasma film forming apparatus, an electrode substrate 3 on which an electrode 2 is arranged is installed in a vacuum vessel 5. The electrode substrate 3 is made of a dielectric (glass)
It consists of a plate (1m × 1m). Electrode 2 (length D95cm,
A number of stripes having a width W of 2.5 mm and a thickness of H 100 μm) are arranged on the electrode substrate 3 in a stripe shape. The distance between adjacent electrodes 2 is 5 mm. The power supply unit 1 is connected to each electrode 2 via an introduction terminal 7.

A holder 8 is provided at a position facing the electrode 2, and the film forming substrate 4 is held by the holder 8. Holder 8
A heater (not shown) for heating the film-forming substrate 4 is provided on the back surface of the substrate. Further, a gas supply unit 13 for supplying a material gas is provided, and a gas introduction hole 6 for introducing the material gas into the vacuum vessel 5 is provided on the electrode substrate 3 side. Further, a mechanical booster pump and a rotary pump (both not shown) are attached to the vacuum vessel 5.

Next, the pressure dependence of the discharge starting voltage will be described. As the voltage application mode, the pressure dependency in the case of the above-described pattern 1 was evaluated. For comparison, pressure dependency was similarly evaluated for Pattern 2 as well.

FIG. 5 shows the results. As shown in FIG. 5, in the case of the pattern 1, it was found that the range of the pressure in which the plasma could be generated was extended to the lower pressure side as compared with the case of the pattern 2. This, as already explained,
In the case of pattern 2, only one discharge path is formed, whereas in the case of pattern 1, as shown in FIG. 4, two discharge paths of discharge paths 11a and 11b are formed as discharge paths. It is considered that the range of pressure at which the plasma film forming apparatus can operate is widened.

In the case of the pattern 1, it is considered that the discharge by the discharge path 11b is dominant in the high voltage side area and the discharge by the discharge path 11a is dominant in the low voltage side area. As described above, it was found that by expanding the operable pressure range, a film such as a silicon nitride film or a silicon oxide film could be formed on the film formation substrate in addition to the amorphous silicon film. This will be described in detail later.

Embodiment 2 A result of forming an amorphous silicon film using the plasma film forming apparatus according to Embodiment 2 of the present invention will be described.
SiH ₄ (flow rate 1 L / min (1000
sccm)) and H ₂ (flow rate ₂ L / min (2000 sc)
cm)). When the temperature of the film forming substrate 4 is 2
The temperature was set to 00 ° C.

FIGS. 7 (a) to 7 (d)
The voltage application form of pattern 3 shown in FIG. That is, the electrode 2a (cathode electrode) to which a voltage is applied and the electrode 2b (anode electrode) at the ground potential are alternately arranged, and the relative arrangement relationship between the cathode electrode 2a and the anode electrode 2b is maintained. The position of the electrode was changed with time.

At this time, the voltage waveform is changed to a pulse width of 10 μs
The voltage was set to c, and a voltage was alternately applied to each electrode.
Further, the voltage value applied to the cathode electrode 2a is -500V.
And As a film forming substrate 4 on which an amorphous silicon film was grown, a glass plate having a thickness of 1.9 mm was placed at a position 15 mm away from the electrode substrate 3.

On the other hand, for comparison, FIGS.
An amorphous silicon film was formed based on the voltage application mode of pattern 2 shown in (d). In pattern 2, the positions of the cathode electrode 2a and the anode electrode 2b do not change with time. Other conditions were set the same as the above-mentioned conditions.

An evaluation result of the amorphous silicon film formed on the film formation substrate will be described. The film thickness uniformity of the amorphous silicon film in the surface of the film-forming substrate when the voltage application mode was pattern 3 was ± 9%, which was a level applicable to an actual device. On the other hand, in the case of pattern 2, the film thickness uniformity was ± 30%, which was a level that could not be applied to an actual device.

As shown in FIG. 8, the film thickness was measured at nine points (black circles) on the surface of the film-forming substrate. When the formed film has irregularities, the number of measurement points (white circles) was further increased around the measurement points (black circles) in order to perform a more accurate evaluation. In addition, the position of the measurement point around the film-forming substrate was located inside the length L (2.5 cm) from the edge.

In the case of pattern 2, the cathode electrode 2a
Since the positional relationship between the electrode and the anode electrode 2b does not change with time, the cathode sheath, which is a radical generator, is also at a fixed position. For this reason, it is considered that the distribution of the amount of radicals diffused from the radical generating unit becomes non-uniform and the uniformity of the film thickness deteriorates.

On the other hand, in the case of the pattern 3, as described above, since the position of the radical generating portion changes with time, the distribution of the radical generating portion is made uniform by averaging over time. As a result, it is considered that the film thickness uniformity of the amorphous film formed on the film formation substrate can be improved.

Third Embodiment The result of forming an amorphous silicon film using the plasma film forming apparatus according to the third embodiment of the present invention will be described.

In this case, the power supply unit 1
(A) to (d) of the pattern 4 shown in FIG. That is, three electrodes 2b (anode electrodes) at the ground potential are arranged between the electrodes 2a (cathode electrodes) to which a voltage is applied, and the relative arrangement relationship between the cathode electrodes 2a and the anode electrodes 2b is changed. While holding, the position of each electrode was changed with time. At this time, the voltage waveform was set to a pulse width of 10 μsec, and a voltage was sequentially applied to each electrode. Other conditions were the same as those described in the second embodiment.

An evaluation result of the amorphous silicon film formed on the film formation substrate will be described. When the voltage application form is pattern 4, the film thickness uniformity of the amorphous silicon film in the surface of the film formation substrate is ± 5%.
It was found that the film thickness uniformity was further improved as compared with the case of.

As described above, since the longer discharge path is formed as the discharge path in the pattern 4, the radical generating portion is also formed in a wider range in the horizontal direction, and the radical generating section is formed. Since the positions of the radicals change with time, the radical generating portions overlap with each other.
As shown in FIG. 0, the distribution of the radical generating portions is further uniformed. As a result, it is considered that the film thickness uniformity of the amorphous silicon film formed on the film formation substrate can be further improved.

Fourth Embodiment A result of forming an amorphous silicon film using a plasma film forming apparatus according to a fourth embodiment of the present invention will be described.

In this case, the pattern of voltage application was pattern 4 as in the third embodiment. The pressure in the vacuum vessel 5 is set to 4
It was set to 0 Pa. This pressure, as already explained,
In the pressure dependency of the discharge starting voltage, the pressure is a pressure near the local minimum value of the voltage located on the low voltage side. In this case, the longer one of the two discharge paths becomes dominant. For other conditions, see the second embodiment.
The same conditions as those described in were used.

The evaluation result of the amorphous silicon film formed on the film formation substrate will be described. When the voltage application mode is pattern 4 and the pressure is 40 Pa, the film thickness uniformity of the amorphous silicon film on the film formation substrate surface is ± 3.
%Met. It was found that even when the voltage application mode was the same pattern 4, the film thickness uniformity was further improved compared to the second embodiment in which the pressure was set to 80 Pa.

As described above, a longer discharge path is formed as the discharge path in the pattern 4, but the longer discharge path becomes dominant when the pressure is set to the low pressure side, and the radical generation section is formed. Is also formed over a wider area in the horizontal direction.

Further, the distance of one movement of the cathode electrode 2a and the anode electrode 2b in a temporal change is shorter than the length of the long discharge path. As a result, the radical generation unit formed at a certain time and the radical generation unit formed at the next time can be reliably overlapped with each other. As shown in FIG. Will be further uniformized. As a result, it is considered that the film thickness uniformity of the amorphous film formed on the film formation substrate is further improved.

Fifth Embodiment In the second to fourth embodiments, the case where the amorphous silicon film is formed on the film formation substrate has been described. It has been confirmed that the plasma film forming apparatus according to the present invention can form a film other than the amorphous silicon film on the film forming substrate.

First, for example, material gases are SiH ₄ (flow rate of about 0.1 L / min (100 sccm)), N ₂ (flow rate of about 1 L / min (1000 sccm)), Ar (flow rate of about 1 L / min (1000 sccm)), It was confirmed that a silicon nitride film could be formed by setting the film formation substrate temperature to about 350 ° C., the voltage application mode to Pattern 1, and the pressure to about 5 Pa.

In a normal plasma CVD method, a silicon nitride film is formed under a pressure of 130 to 400 Pa. Further, it was experimentally confirmed that the lower limit of the pressure at which a silicon nitride film can be formed in this plasma CVD method is about 40 Pa. Therefore, it was found that a silicon nitride film can be formed under a lower pressure condition by applying the present plasma film forming apparatus.

As another film, for example, a material gas is SiH ₄ (flow rate: about 0.08 L / min (80 scc)
m)), N ₂ O (flow rate about 5 L / min (5000 scc)
m)), it was confirmed that a silicon oxide film could be formed by setting the film formation substrate temperature to about 300 ° C., the voltage application mode to Pattern 1, and the pressure to about 5 Pa. In this case, as in the case of the silicon nitride film, the normal plasma C
It has been found that a silicon oxide film can be formed under a lower pressure condition than in the case where the VD method is used.

Further, the material gas is SiH ₄ (flow rate of about 0.0
2 L / min (20 sccm)), He (flow rate about 1 L /
min (1000 sccm)), Ar (flow rate about 2 L / m)
in (2000 sccm)) and the film forming substrate temperature is about 300
° C, voltage application pattern 1 and pressure about 5P
It was confirmed that by setting a, an epitaxially grown silicon film could be formed.

In the ordinary epitaxial growth method, the film is formed under the condition that the temperature of the substrate is about 500 ° C. or more.
Therefore, it was found that by applying the present plasma film forming apparatus, a silicon film grown epitaxially could be formed under lower temperature conditions.

It was also confirmed that the film thickness uniformity of these films was at a level applicable to devices. Thus, it was found that the present plasma film forming apparatus can uniformly form a silicon nitride film, a silicon oxide film, and a silicon film grown epitaxially on a film forming substrate in addition to the amorphous silicon film.

In the above-described plasma film forming apparatus, the width of the electrode is 2.5 mm, the distance between the electrodes is 5 mm, and the distance between the electrode and the film-forming substrate is 15 mm. About 30 of this size
It is considered that the size can be increased up to about twice.
However, in consideration of cost, it can be considered that, in reality, the size can be changed in a range from a fraction to several times of each of the above dimensions.

The embodiment disclosed this time is an example in all respects, and should be considered as not being restrictive. The present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0095]

According to the plasma film forming apparatus of one aspect of the present invention, the radical generation region moves temporally along the substrate surface and a discharge path longer than the interval between adjacent electrodes is formed. By performing at least one of the above, the radical generation region expands along the surface of the substrate. As a result, the distribution of the radical generation region becomes more uniform, and a film with high uniformity can be formed in the substrate surface.

Further, according to the film forming method in another aspect of the present invention, the radical generation region spreads along the surface of the substrate, so that the distribution of the radical generation region becomes more uniform, and the uniformity in the substrate surface is high. A film is formed.

As described above, a plasma film forming apparatus capable of forming a uniform film on a film forming substrate having a relatively large area can be realized.

For example, in order to fabricate a liquid crystal display, it is necessary to uniformly fabricate a TFT (thin film transistor) as a switching element in a substrate surface.
In other words, high-quality and highly uniform film forming technology on a film forming substrate having a large area is indispensable.
By applying the present plasma film forming apparatus, such a demand can be realized.

It has also been found that the operating pressure can also be expanded to a lower pressure side, and thus, in addition to the amorphous silicon film, a silicon nitride film, a silicon oxide film or an epitaxially grown silicon film can be formed with high quality and high uniformity. It turned out that a membrane was possible.

In addition to a liquid crystal display, an amorphous silicon solar cell forms an amorphous silicon film by a plasma CVD method, and this amorphous silicon film can be formed using the present plasma film forming apparatus.

In particular, in the case of an amorphous silicon solar cell for residential use, it is indispensable to form a film on a substrate having a relatively large area. A highly reliable amorphous silicon solar cell can be provided by applying a plasma film formation apparatus.

[Brief description of the drawings]

FIG. 1 is a perspective view of a plasma film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the plasma deposition apparatus shown in FIG. 1 in the embodiment.

FIG. 3 is a diagram showing an application form (pattern 1) of a voltage applied to an electrode and a time change of a distribution of a radical generation part in the embodiment, wherein (a) to (d) show times t1 to t4, respectively. FIG. 7 is a diagram showing a voltage application mode and a distribution of radical generating sections in FIG.

FIG. 4 is a diagram showing discharge paths in pattern 1 and pattern 2 in the embodiment.

FIG. 5 is a diagram showing pressure dependency of a discharge starting voltage in the case of pattern 1 and pattern 2 in the embodiment.

FIG. 6 is a diagram showing an application mode (pattern 2) of a voltage applied to an electrode for comparison and a temporal change in distribution of a radical generation unit in the embodiment, where (a) to (d) are respectively It is a figure which shows the application form of the voltage and distribution of a radical generation part in the time t1-t4, and (e) shows the distribution of the radical generation part averaged over time.

FIGS. 7A and 7B are diagrams showing the application form (pattern 3) of a voltage applied to an electrode for evaluating film formation and a change over time in the distribution of radical generating units in Embodiment 2 of the present invention, and FIG. (D) shows the voltage application form and the distribution of the radical generator at times t1 to t4, respectively.
FIG. 4 is a diagram showing the distribution of radical generating parts averaged over time.

FIG. 8 is a perspective view showing measurement points when measuring the thickness of a formed film in the same embodiment.

FIGS. 9A and 9B are diagrams showing a form of application of a voltage (pattern 4) applied to an electrode for performing film formation evaluation and a change over time of a distribution of radical generating units in Embodiment 3 of the present invention, and FIG. (D) shows the voltage application form and the distribution of the radical generator at times t1 to t4, respectively.
FIG. 4 is a diagram showing the distribution of radical generating parts averaged over time.

FIG. 10 is a diagram showing a distribution of radical generating portions at an operating point (a) in the pressure dependence of a discharge starting voltage in pattern 1.

FIG. 11 is a diagram showing a distribution of radical generating portions at an operating point (b) in the pressure dependence of a discharge starting voltage in pattern 1;

FIG. 12 is a sectional view of a conventional plasma film forming apparatus.

13 is a partial perspective view of the plasma film forming apparatus shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Power supply part, 2 electrodes, 2a cathode electrode, 2b anode electrode, 3 electrode substrate, 4 film formation substrate, 5 vacuum vessel, 6 gas inlet, 7 inlet terminal, 8 holder, 1
1, 11a, 11b Discharge path, 12 Radical, 13
Gas supply unit, 17 radical generation unit (region).

Continued on the front page F-term (reference) 4G075 AA24 AA30 BC01 BC04 CA25 CA47 EB42 EC21 ED11 EE31 FB02 FB12 4K030 AA06 AA17 AA18 AA24 BA29 BA30 BA40 BA44 CA17 FA03 KA15 KA30 LA15 LA16 LA18 5F045 AA08 CA04 AD06 EH12 EH20

Claims (12)

[Claims] A processing chamber; a material gas inlet for introducing a material gas into the processing chamber; and an electrode including a cathode electrode and an anode electrode, wherein the electrode includes a cathode electrode and an anode electrode. Moving the radical generation region of the material gas formed based on the discharge path generated between the substrates along the surface of the substrate on which the process is performed by introducing the radical generation region into the processing chamber, and moving the radical generation region on the surface of the substrate. A plasma film forming apparatus for performing at least one of generating a discharge path having a longer length than an interval between adjacent electrodes. 2. A plurality of the anode electrodes and the plurality of the cathode electrodes are respectively disposed so as to face a substrate and become substantially parallel to the substrate, and at least two of the anode electrodes are disposed between the adjacent cathode electrodes. The plasma deposition apparatus according to claim 1, wherein: 3. In the cathode electrode and the anode electrode, while maintaining the relative positional relationship between the cathode electrode and the anode electrode, the respective positions of the cathode electrode and the anode electrode are temporally changed. The plasma deposition apparatus according to claim 2, which changes. 4. The plasma according to claim 3, wherein a moving distance per change in the temporal position of the cathode electrode and the anode electrode is shorter than a length of a discharge path longer than between the adjacent electrodes. Film forming equipment. 5. The plasma film forming apparatus according to claim 1, wherein the cathode electrode and the anode electrode are alternately arranged, and their positions alternate with time. 6. A film forming method for forming a predetermined film on a substrate by introducing a material gas into a processing chamber in which a cathode electrode and an anode electrode are arranged, wherein the cathode electrode, the anode electrode, Moving the radical generation region of the material gas formed on the basis of the discharge path occurring temporally along the surface of the substrate and making the length along the surface of the substrate smaller than the distance between adjacent electrodes. A film forming method, comprising: forming a predetermined film on the substrate by performing at least one of generating a long discharge path. 7. A plurality of said anode electrodes and said cathode electrodes are respectively disposed so as to face said substrate and to be substantially parallel to said substrate, and at least two said anode electrodes are provided between adjacent cathode electrodes. The film forming method according to claim 6, wherein 8. In the film forming step, a discharge voltage for starting a discharge between the cathode electrode and the anode electrode is at least two discharge paths generated between the cathode electrode and the anode electrode. The film forming method according to claim 7, wherein a discharge start voltage corresponding to a longer discharge path is set. 9. The film forming method according to claim 8, wherein the discharge voltage is a discharge start voltage corresponding to a lower pressure value in the pressure dependency of the discharge start voltage. 10. In the film forming step, respective positions of the cathode electrode and the anode electrode are temporally changed while maintaining a relative positional relationship between the cathode electrode and the anode electrode. 10. The film forming method according to any one of 6 to 9. 11. In the film forming step, a moving distance per change in a temporal position of the cathode electrode and the anode electrode is shorter than a length of a discharge path longer than between adjacent electrodes. The film forming method according to claim 10. 12. The method according to claim 6, wherein the cathode electrode and the anode electrode are alternately arranged, and in the film forming step, respective positions of the cathode electrode and the anode electrode are alternately changed with time. Film formation method.