JP4470227B2 - Film forming method and thin film transistor manufacturing method - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The invention disclosed in this specification relates to a film formation method using a plasma CVD method and a film formation apparatus capable of performing the film formation method.
[0002]
[Prior art]
As a method for forming an amorphous silicon film or a silicon oxide film, a plasma CVD method is known.
[0003]
In the formation of various thin films by the plasma CVD method, fine particles such as particles and flakes generated during the film formation become a problem.
[0004]
These fine particles
(1) The reaction product formed on the inner wall and electrode of the reaction chamber every time the film is formed is peeled off by obtaining some energy during discharge.
(2) Those produced in the gas phase and not contributing to the formation of the thin film.
So it is mainly composed. In any case, the fine particles are reaction products of raw material gases used for film formation.
[0005]
The fine particles adhere to the film to be formed, and become a factor that significantly deteriorates the film quality.
[0006]
In order to solve this problem, it is effective to increase the number of cleanings in the chamber.
[0007]
However, even if cleaning is performed for each film formation, it is not a fundamental solution because only the number of fine particles generated due to the above (1) can be reduced.
[0008]
Moreover, increasing the number of chamber cleanings is not industrially preferable because it reduces productivity and complicates the operation.
[0009]
[Problems to be solved by the invention]
An object of the invention disclosed in this specification is to provide a technique for suppressing the presence of fine particles generated during film formation by a plasma CVD method from adversely affecting the film quality of a thin film to be formed.
[0010]
[Process leading to the invention]
As a result of eagerly pursuing the point at which the fine particles of the reaction product adhere to the film to be formed, it was found that the fine particles adhere to the film before and after the film formation and adversely affect the film quality. did.
[0011]
The process of obtaining the above findings is shown below. In general, the plasma CVD method has a parallel plate type structure as shown in FIG. 1, a sample (substrate) 11 is disposed on one electrode 12 held at a ground potential, and a high frequency is applied to the other electrode 15 facing the plasma CVD method. The power supply 16 is connected.
[0012]
FIG. 7 shows the timing relationship between the supply of the source gas and the high frequency discharge (RF discharge) in the case of performing general film formation.
[0013]
In general, in a state where plasma is generated by high frequency discharge, a bias voltage as shown in FIG. 8 is applied between the electrodes.
[0014]
This bias voltage is a large negative voltage on the power supply electrode 15 side and a relatively small negative voltage on the ground electrode 12 side.
[0015]
In general, fine particles floating in the chamber 11 are negatively charged. Therefore, during discharge, the fine particles are repelled from the electrode 12, and the fine particles are unlikely to adhere to the substrate placed on the electrode 12.
[0016]
That is, during the film formation shown in FIG. 7, the fine particles are unlikely to adhere to the film.
[0017]
However, when the discharge is completed, the self-bias application state as shown in FIG. 8 disappears, and accordingly, the fine particles fall down on the substrate and adhere to the surface to be formed. Further, fine particles adhere to the surface of the substrate (surface of the surface to be formed) due to static electricity.
[0018]
[Means for Solving the Problems]
The invention disclosed in this specification pays attention to the phenomenon that the self-bias applied to the electrode on which the substrate is placed disappears at the end of the above-described discharge, and as a result, fine particles adhere to the surface of the substrate. It is.
[0019]
Therefore, in the invention disclosed in this specification, the discharge is maintained even after the film formation is completed.
[0020]
Then, the discharge is stopped after all the fine particles present in the atmosphere are exhausted, thereby suppressing the fine particles from adhering to the surface of the film.
[0021]
That is, the self-bias state as shown in FIG. 8 is maintained until the fine particles are exhausted after the film formation is completed.
[0022]
In the invention disclosed in this specification in order to realize the above state, the atmosphere is switched from the film forming gas to the discharge gas in a state where the high frequency discharge is maintained.
[0023]
In this way, the supply of the film forming gas is completed, and the discharge is maintained even after the film formation is completed, and the bias state shown in FIG. 8 can be maintained during that time.
[0024]
By maintaining this state for a while, the negatively charged fine particles in the atmosphere are exhausted to the outside in a state where they cannot adhere to the substrate.
[0025]
Then, the high frequency discharge is stopped in a state where the fine particles are exhausted to the outside, that is, the atmosphere is changed, and further, the supply of the gas for discharge is stopped.
[0026]
By doing so, it is possible to prevent fine particles from adhering to the surface of the film to be formed.
[0027]
Note that the film-forming gas refers to a gas containing a component of a film to be formed and a component constituting fine particles.
[0028]
As a kind of film forming gas, if a silicon film is formed, silane, disilane, and methane can be used if a hard carbon film is formed.
[0029]
The discharge gas alone refers to a gas that does not contribute to film formation or fine particle formation, but merely discharges and contributes to plasma formation. Examples of the discharge gas include hydrogen gas and helium gas.
[0030]
The kind of film to be formed is not particularly limited, and examples thereof include a general semiconductor film and an insulating film. The film to be formed may be a compound film.
[0031]
One of the inventions disclosed in this specification is:
A first stage of forming a plasma by forming a plasma by performing a high frequency discharge in a state where a film forming gas is supplied;
A second stage in which the film formation gas is switched to the discharge gas, and subsequently high frequency discharge is performed to form a plasma that does not follow the film formation;
It is characterized by having.
[0032]
In the above configuration,
It is important to keep the pressure in the atmosphere constant in the first stage and the second stage. This is in order not to change the conditions under which plasma is formed.
[0033]
For example, when the pressure of the atmosphere changes abruptly, sudden discharge such as arc discharge occurs and the film quality to be formed may be greatly impaired. In order to prevent this, the pressure in the atmosphere is kept constant in the first stage and the second stage as described above.
[0034]
Other aspects of the invention are:
A first stage in which a film is formed by forming a plasma by performing a high frequency discharge in a state where a film forming gas is supplied;
A second stage in which the film formation gas is switched to the discharge gas, and subsequently high frequency discharge is performed to form a plasma that does not follow the film formation;
It is a film forming apparatus having a function of performing.
[0035]
In this configuration, it is important to have a function of keeping the pressure in the atmosphere constant in the first stage and the second stage.
[0036]
In addition, the configuration of other inventions is as follows:
A method in which high-frequency discharge is caused between parallel plate electrodes to form a film by a plasma gas phase reaction,
By stopping the supply of the deposition gas with the self-bias applied to the surface to be formed, and simultaneously supplying the discharge gas, the self-bias is applied to the formed surface even after the film formation is completed. It is characterized by being a gas phase reaction method characterized by maintaining.
[0037]
In addition, the configuration of other inventions is as follows:
An apparatus for forming a film by a plasma gas phase reaction by generating a high frequency discharge between parallel plate electrodes,
By stopping the supply of the deposition gas with the self-bias applied to the surface to be formed, and simultaneously supplying the discharge gas, the self-bias is applied to the formed surface even after the film formation is completed. The film forming apparatus is characterized by having a function of maintaining.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
In the formation of an amorphous silicon film by a plasma CVD method using silane as a film formation gas, the silane gas and the hydrogen gas are exchanged at the end of the film formation. At this time, the high frequency discharge is maintained.
[0039]
Thus, a state in which a negative self-bias is applied to the surface to be formed can be maintained even after film formation is completed. Then, the discharge with the hydrogen gas is continued for a while until the fine particles, which are negatively charged reaction products, are exhausted to the outside of the atmosphere, thereby preventing the fine particles from adhering to the formation surface.
[0040]
【Example】
[Example 1]
(Explanation of deposition system)
First, an outline of a film forming apparatus used in this embodiment will be described. FIG. 1 schematically shows a plasma CVD apparatus for forming an amorphous silicon film.
[0041]
In this apparatus, a pair of parallel plate electrodes 12 and 15 are provided inside a decompression chamber 10 made of stainless steel.
[0042]
A substrate (sample) 11 is disposed on one electrode 12 connected to the ground potential. A high frequency power supply 16 is connected to the other electrode 15. Although not shown in the figure, a matching circuit is disposed between the electrode 15 and the high-frequency power supply 16.
[0043]
The high-frequency power source has a function of outputting the required high-frequency power. In general, 13.56 MHz is used as the frequency of the high-frequency power. Of course, other frequencies may be used. However, it is necessary that the frequency is such that a self-bias is formed as shown in FIG.
[0044]
In the decompression chamber 10, gas supply systems 17 and 18 are arranged for supplying gas therein.
[0045]
Here, 17 is a gas line for supplying silane gas, and 18 is a gas line for supplying hydrogen gas.
[0046]
The decompression chamber 10 is provided with an exhaust system 13 including an exhaust pump 14 for making a decompressed state that requires the inside.
[0047]
Although not shown, the decompression chamber 10 is provided with a door for carrying the substrate into the apparatus from the outside.
[0048]
In this embodiment, rectangular electrodes having an area of 490 cm ² are arranged as electrodes. The high frequency power supply 16 supplies high frequency power with a frequency of 13.56 MHz and an output of 20 W to the electrode 15 via a matching circuit (not shown).
[0049]
(Method for forming amorphous silicon film)
Here, an example in which an amorphous silicon film is formed using the method disclosed in this specification will be described.
[0050]
First, a door (not shown) provided in the decompression chamber is opened, and the substrate 11 is carried into the chamber 10. The substrate 11 is disposed on the electrode 12 connected to the ground potential.
[0051]
Next, the door (not shown) is closed, and the decompression chamber 10 is sealed. Then, the exhaust pump 14 is operated to bring the inside of the decompression chamber 10 into a decompressed state.
[0052]
Here, in order to eliminate impurities in the chamber, it is preferable to supply nitrogen gas from a gas supply system (not shown), and once the chamber is filled with nitrogen gas, and then the inside of the decompression chamber 10 is brought into a decompressed state.
[0053]
At this stage, it is preferable that the inside of the chamber 10 be in a high vacuum state as much as possible.
[0054]
Next, an amorphous silicon film is formed on the substrate 11 in accordance with the timing chart shown in FIG.
[0055]
First, the inside of the decompression chamber 10 is brought into an ultra-high vacuum state (a state where exhaust is as much as possible). Then, silane gas (SiH ₄ gas) is supplied from the gas supply system 17 at a flow rate of 100 sccm. In this embodiment, the pressure in the decompression chamber 10 is 0.5 Torr under these conditions. (The relationship between flow rate and pressure depends on the volume of the chamber and the capacity of the exhaust pump)
[0056]
Then, high-frequency power (RF power) (output 20 W) from the high-frequency power supply 16 is supplied in a state where the inside of the chamber 10 has a predetermined pressure.
[0057]
The time point at which the supply of high-frequency power is started can be regarded as the film formation start point.
[0058]
The film formation is completed by stopping the supply of silane gas. Here, the supply of hydrogen gas is performed from the gas system 18 at the same time as the supply of silane gas is stopped.
[0059]
The supply of hydrogen gas is 100 sccm. This is to minimize the pressure change in the chamber following the gas switching.
[0060]
By doing so, the film formation can be stopped in a state where the discharge is continued (a state where plasma is generated).
[0061]
In this embodiment, the switching timing is set so that there is as little pressure change as possible according to the gas switching.
[0062]
Here, the time of the transient state according to the stop of the syngas and the time of the transient state according to the start of the supply of hydrogen gas are set to be the same, and further, the two transient states are set to overlap. The time for the transient state is 2 seconds.
[0063]
Film formation ends when the supply of silane gas is stopped. And the discharge by hydrogen gas is continued for the predetermined time t.
[0064]
The value of t varies depending on the volume of the chamber, gas supply capability, exhaust system capability, and the like.
[0065]
What is important is to make the value of t larger than the time for replacing the gas in the chamber (this is assumed to be t ′). That is, t> t ′.
[0066]
By doing so, it is possible to prevent fine particles from being present in the atmosphere in a state where the discharge is stopped, and it is possible to prevent fine particles from adhering to the surface of the formed film.
[0067]
If the relationship expressed by t> t ′ is not observed, a state in which the fine particles are suspended in the atmosphere after the discharge is stopped is realized, and the fine particles adhere to the surface of the film. In this case, the effect of the invention cannot be obtained.
[0068]
After stopping the discharge, the supply of hydrogen gas is stopped. Thus, the film forming process is completed.
[0069]
The film formation method shown in FIG. 2 is characterized in that the film formation stop timing and the discharge stop timing are shifted. That is, after the film formation is completed, the discharge is continued so that the formation of plasma without affecting the film formation is continued, so that a self-bias as shown in FIG. 8 is formed.
[0070]
By doing so, it is possible to prevent fine particles from adhering to the film after the film formation is completed.
[0071]
[Example 2]
In this embodiment, a process of manufacturing a thin film transistor using the method for forming an amorphous silicon film described in Embodiment 1 is shown.
[0072]
FIG. 3 shows a manufacturing process of this example. First, as shown in FIG. 3A, a silicon oxide film 102 is formed as a base film on a glass substrate 101 to a thickness of 300 nm by a plasma CVD method.
[0073]
Next, an amorphous silicon film 103 is formed to a thickness of 50 nm by the method shown in the first embodiment. In this way, the state shown in FIG.
[0074]
Next, laser light is irradiated to crystallize the amorphous silicon film 103. As a method for crystallizing the amorphous silicon film, methods such as heating, a combination of heating and intense light irradiation, a combination of heating and laser light irradiation, and the like can be used.
[0075]
Next, the obtained crystalline silicon film is patterned to obtain a pattern indicated by 104 in FIG.
[0076]
Further, a silicon oxide film 105 functioning as a gate insulating film is formed to a thickness of 100 nm by plasma CVD.
[0077]
Further, a film made of aluminum is formed by sputtering to a thickness of 400 nm. Then, this aluminum film is patterned using a resist mask 107. In this way, a pattern indicated by 106 is obtained. This pattern 106 will be a basis for forming a gate electrode later.
[0078]
In this way, the state shown in FIG. Next, anodic oxidation using the aluminum pattern 106 as an anode is performed with the resist mask 107 remaining. Here, an aqueous solution containing 3% by volume of oxalic acid is used as the electrolytic solution, and anodization is performed using the pattern 106 as an anode and platinum as a cathode.
[0079]
In this step, the anodic oxide film 108 is formed on the side surface of the aluminum pattern 106 in the state shown in FIG.
[0080]
The thickness of the anodic oxide film 108 is 400 nm. The anodic oxide film 108 formed in this step is obtained as having a porous shape (porous shape).
[0081]
After obtaining the state shown in FIG. 3C, the resist mask 107 is removed. Then, anodic oxidation is performed again. Here, an electrolytic solution obtained by neutralizing an ethylene glycol solution containing 3% by volume of tartaric acid with aqueous ammonia is used.
[0082]
In this step, an anodic oxide film is formed as indicated by 109 in FIG. 3D because the electrolytic solution penetrates into the porous anodic oxide film 108. The thickness of the anodic oxide film 109 is 70 nm. Here, a pattern indicated by 110 is a gate electrode.
[0083]
The anodized film 109 formed in this step has a dense film quality.
[0084]
In this way, the state shown in FIG. Next, doping with an impurity element is performed in the state shown in FIG. Here, phosphorus is doped by plasma doping in order to manufacture an N-channel TFT.
[0085]
Here, a plasma doping method is used in which phosphorus ions are extracted from a plasma containing phosphorus ions by an electric field, and are further electrically accelerated to perform doping. However, an ion implantation method in which phosphorous ions are electrically accelerated after mass separation may be used as the doping means.
[0086]
This doping is performed under conditions for forming normal source and drain regions. In this way, as shown in FIG. 4A, phosphorus is doped in the regions 111 and 115 in a self-aligning manner. Here, 111 is a source region and 115 is a drain region.
[0087]
Next, the porous anodic oxide film 108 is removed to obtain the state shown in FIG. Then, phosphorus is doped again by plasma doping.
[0088]
This doping is performed under the condition of light doping as compared with the doping performed in the state of FIG.
[0089]
In this step, the low concentration impurity concentration regions 112 and 114 are formed in a self-aligning manner. A region 113 is defined as a channel formation region. (Fig. 4 (B))
[0090]
Here, the low concentration impurity concentration means that the concentration of the dopant (in this case, phosphorus) is lower than that of the source region 111 and the drain region 115.
[0091]
When the doping is completed, laser light irradiation is performed to improve the crystallinity of the doped region and activate the dopant.
[0092]
Although an example in which laser light irradiation is performed is shown here, a method using strong light irradiation may be used.
[0093]
Next, as shown in FIG. 4C, a silicon nitride film 116 is formed to a thickness of 150 nm by a plasma CVD method, and a silicon oxide film 117 is further formed to a thickness of 400 nm by a plasma CVD method.
[0094]
Further, an acrylic resin is applied to form a resin film 118. When a resin film is used, the surface can be made flat. In addition to the acrylic resin, resin materials such as polyimide, polyimide amide, polyamide, and epoxy can be used.
[0095]
Next, contact holes are formed, and a source electrode 119 and a drain electrode 120 are formed. Thus, the TFT is completed.
[0096]
In this embodiment, an example in which a glass substrate is used as the substrate is shown. However, a quartz substrate, a semiconductor substrate on which an insulating film is formed, or a metal substrate may be used. (These are collectively referred to as a substrate having an insulating surface.)
[0097]
In this embodiment, an example in which the semiconductor film constituting the active layer of the TFT is a crystalline silicon film is shown, but the active layer may be constituted by an amorphous silicon film.
[0098]
In this embodiment, an example in which aluminum is used for the gate electrode has been described. However, another silicon material, a silicide material, or an appropriate metal material may be used.
[0099]
In this embodiment, an example of a top gate type TFT in which the gate electrode is above the active layer is shown, but a bottom gate type TFT in which the gate electrode is below the active layer (substrate side) may be used. .
[0100]
Example 3
The present embodiment is an example in which the configuration shown in the first embodiment is further improved.
[0101]
In this embodiment, film formation is performed according to the timing chart shown in FIG. What is important in the timing chart of FIG. 5 is that the discharge power is gradually reduced in the discharge after the film formation is completed (that is, after the supply of silane gas is stopped).
[0102]
By doing so, it is possible to prevent the fine particles adhering to the inner wall of the chamber from being released into the atmosphere. In addition, it is possible to suppress the plasma damage to the formed film.
[0103]
Here, an example is shown in which the discharge power of 20 W is reduced to 5 W after the film formation is completed (after the supply of silane gas is stopped).
[0104]
The method of changing the discharge power may be further stepwise. Further, it may be changed continuously. Moreover, it is good also as what combined the step change and the continuous change.
[0105]
Example 4
The present embodiment relates to a configuration in consideration of the start of discharge in the configuration shown in the first embodiment.
[0106]
When film formation is performed at the timing shown in FIG. 2 shown in the first embodiment, the start of discharge coincides with the start of film formation. That is, in this case, film formation is started by starting discharge. In other words, film formation is started simultaneously with the start of plasma generation.
[0107]
However, depending on the structure of the electrode and the like, a period in which the discharge state is not stable at the start of discharge may last for several seconds.
[0108]
In order to suppress this problem, in this embodiment, first, an atmosphere is used as a discharge gas, and discharge is performed in that state. Next, the gas is switched to a film forming gas, and the film is formed in a state where the discharge is continued.
[0109]
If an amorphous silicon film is formed, hydrogen is used as a discharge gas and silane is used as a film formation gas.
[0110]
FIG. 6 shows a timing chart when the film formation of this embodiment is performed. Also in this embodiment, it is preferable that the pressure change in the atmosphere following the gas switching is as small as possible.
[0111]
By performing film formation at a timing as shown in FIG. 6, it is possible to prevent the instability of the discharge during the period indicated by t at the start of discharge from affecting the film formation.
[0112]
As shown in FIG. 6, in this embodiment, just before the start of film formation and immediately after the start of film formation, hydrogen gas, which is a discharge gas, is introduced only for discharge (only for generating plasma). .
[0113]
By doing so, instability at the start of discharge can be prevented from affecting the film formation, and fine particles after film formation can be prevented from adhering to the surface of the film.
[0114]
Example 5
In this example, a hard carbon film represented by a DLC film (diamond-like carbon film) is formed.
[0115]
There are various types of hard carbon films other than DLC films, and there is no fixed classification method or evaluation. Therefore, here, the carbon film used as a protective film or a wear-resistant film is generically referred to as a hard carbon film.
[0116]
When forming a hard carbon film, a method is used in which the film is formed by striking carbon ions against the surface to be formed using a strong self-bias.
[0117]
In such a film forming method, the surface to be formed is arranged on the electrode 15 side connected to the high frequency power source 16 of the plasma CVD apparatus as shown in FIG.
[0118]
That is, the substrate 11 (or a base body replacing it) is disposed on the electrode 15 side.
[0119]
The invention disclosed in this specification is useful even in such a configuration. That is, by performing film formation according to the timing chart as shown in FIG. 2, it is possible to prevent fine particles from adhering to the surface of the formed film.
[0120]
In this case as well, after the film formation is completed, self-bias according to the formation of plasma is applied to the surface to be formed, and furthermore, the discharge is stopped in a state where the atmosphere in the chamber is changed, so that the fine particles are applied to the surface to be formed. It can be prevented from adhering.
[0121]
Example 6
This embodiment is an example in which the invention disclosed in this specification is used for continuous film formation.
[0122]
In a multi-chamber type film forming apparatus in which a large number of film forming chambers are connected in series or in parallel, when different films are stacked in multiple layers, the presence of fine particles remaining on the underlying film becomes a particular problem.
[0123]
Therefore, for example, the method shown in the first embodiment is executed in each film formation. By doing so, the above problem can be solved.
[0124]
In the above description, the variations have been described based on the first embodiment. However, the embodiments can be combined as necessary.
[0125]
【The invention's effect】
By utilizing the invention disclosed in this specification, it is possible to suppress the presence of fine particles, which are reaction products generated during film formation in the plasma CVD method, from adversely affecting the film quality of a thin film to be formed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a plasma CVD apparatus.
FIG. 2 is a diagram showing timing of gas supply and high-frequency power (RF) supply.
FIG. 3 illustrates a manufacturing process of a thin film transistor.
4A and 4B illustrate a manufacturing process of a thin film transistor.
FIG. 5 is a diagram showing the timing of gas supply and high-frequency power (RF) supply.
FIG. 6 is a diagram showing timing of gas supply and high-frequency power (RF) supply.
FIG. 7 is a diagram showing the timing of conventional gas supply and high-frequency power (RF) supply.
FIG. 8 is a diagram showing a state of self-bias during high-frequency discharge.
[Explanation of symbols]
10 Chamber 11 Substrate (sample)
12 Electrode 13 Exhaust System 14 Exhaust Pump 15 Electrode 16 High Frequency Power Supply 17 Silane Gas Supply System 18 Hydrogen Gas Supply System 101 Glass Substrate 102 Base Film (Silicon Oxide Film)
103 Amorphous silicon film 104 Active layer (crystalline silicon film)
105 Gate insulating film 106 Aluminum pattern 107 Resist mask 108 Porous anodic oxide film 109 Anodized film 110 having a dense film quality 110 Gate electrode 111 Source region 115 Drain region 112 Low concentration impurity region 114 Low concentration impurity region 113 Channel formation region 116 Silicon nitride film 117 Silicon oxide film 118 Acrylic resin film 119 Source electrode 120 Drain electrode

Claims (21)

A first stage of forming a film using a high frequency discharge while supplying a film forming gas;
A second stage in which the supply of the discharge gas is started at the same time as the stop of the supply of the film forming gas is started while the pressure in the chamber is kept constant while maintaining the high-frequency discharge;
A third stage of maintaining the high frequency discharge by continuing to supply the discharge gas after the supply of the film forming gas is stopped;
A fourth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
The film forming method is characterized in that the time for maintaining the third stage is longer than the time for changing the atmosphere in the second stage. A first stage of forming a film using a high frequency discharge while supplying a film forming gas;
A second stage in which the supply of hydrogen gas is started simultaneously with stopping the supply of the film forming gas while keeping the pressure in the chamber constant while maintaining the high frequency discharge;
A third stage of maintaining the high frequency discharge by continuing to supply the hydrogen gas after the supply of the film forming gas is stopped;
A fourth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
The film forming method is characterized in that the time for maintaining the third stage is longer than the time for changing the atmosphere in the second stage. A first stage of supplying a discharge gas to start high frequency discharge;
A second stage in which the supply of the deposition gas is started at the same time as the supply of the discharge gas is started to be stopped while maintaining the high-frequency discharge;
A third step of forming a film using high frequency discharge while supplying the film forming gas;
A fourth stage of starting supply of the discharge gas at the same time as stopping the supply of the film forming gas while keeping the pressure in the chamber constant while maintaining the high frequency discharge;
After the supply of the film-forming gas is stopped, the fifth stage of maintaining the high-frequency discharge by continuing to supply the discharge gas;
A sixth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
The film forming method is characterized in that the time for maintaining the fifth stage is longer than the time for changing the atmosphere in the fourth stage. A first stage of supplying hydrogen gas and starting high frequency discharge;
A second stage in which the supply of the film forming gas is started at the same time as the stop of the supply of the hydrogen gas is started while maintaining the high-frequency discharge;
A third step of forming a film using high frequency discharge while supplying the film forming gas;
A fourth stage in which the supply of the hydrogen gas is started at the same time as the stop of the supply of the film forming gas while the pressure in the chamber is kept constant while maintaining the high frequency discharge;
A fifth stage of maintaining the high frequency discharge by continuing to supply the hydrogen gas after the supply of the film forming gas is stopped;
A sixth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
The film forming method is characterized in that the time for maintaining the fifth stage is longer than the time for changing the atmosphere in the fourth stage.   5. The film forming method according to claim 1, wherein the film to be formed is a semiconductor film, an insulating film, or a compound film. A first stage of forming an insulating film on a substrate using high frequency discharge while supplying a film forming gas for forming the insulating film;
A second stage of supplying a first discharge gas at the same time as stopping the supply of a film forming gas for forming the insulating film while keeping the pressure in the chamber constant while maintaining a high frequency discharge;
A third stage of maintaining the high frequency discharge by continuing to supply the first discharge gas after the supply of the film forming gas for forming the insulating film is stopped;
A fourth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
A fifth stage of stopping the supply of the first discharge gas;
A sixth step of forming a silicon film on the insulating film using a high frequency discharge while supplying a film forming gas for forming the silicon film;
A seventh stage of supplying a second discharge gas at the same time as stopping the supply of a film forming gas for forming the silicon film while keeping the pressure in the chamber constant while maintaining the high frequency discharge;
An eighth stage of maintaining the high frequency discharge by continuing to supply the second discharge gas after stopping the supply of the film forming gas for forming the silicon film;
A ninth stage in which the power is decreased stepwise or continuously to stop the high frequency discharge;
A tenth stage for stopping the supply of the second discharge gas;
And the time for maintaining the third stage is longer than the time for changing the atmosphere in the second stage, and the time for maintaining the eighth stage is the time for changing the atmosphere in the seventh stage. A film forming method characterized by being longer than A first stage of forming a silicon film on a substrate using a high frequency discharge while supplying a film forming gas for forming the silicon film;
A second stage of supplying a first discharge gas at the same time as stopping the supply of a film forming gas for forming the silicon film while keeping the pressure in the chamber constant while maintaining a high frequency discharge;
A third stage of maintaining the high frequency discharge by continuing to supply the first discharge gas after the supply of the film forming gas for forming the silicon film is stopped;
A fourth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
A fifth stage of stopping the supply of the first discharge gas;
A sixth stage of forming an insulating film on the silicon film using a high frequency discharge while supplying a film forming gas for forming the insulating film;
A seventh stage of supplying a second discharge gas at the same time as starting the stop of the supply of the film forming gas for forming the insulating film while keeping the pressure in the chamber constant while maintaining the high frequency discharge;
An eighth stage of maintaining the high frequency discharge by continuing to supply the second discharge gas after stopping the supply of the film forming gas for forming the insulating film;
A ninth stage in which the power is decreased stepwise or continuously to stop the high frequency discharge;
A tenth stage for stopping the supply of the second discharge gas;
The time for maintaining the third stage is longer than the time for changing the atmosphere in the second stage, and the time for maintaining the eighth stage is the time for changing the atmosphere in the seventh stage. A film forming method characterized by being longer than   3. The film forming method according to claim 1, wherein a self-bias is applied to the film formation surface in the second stage and the third stage.   5. The film formation method according to claim 3, wherein a self-bias is applied to the film formation surface in the fourth stage and the fifth stage. The self-bias is applied to the insulating film surface in the second stage and the third stage, and the self-bias is applied to the silicon film in the seventh stage and the eighth stage. A film forming method characterized by maintaining the state. 8. A state in which a self-bias is applied to the silicon film surface in the second stage and the third stage, and a self-bias is applied to the insulating film in the seventh stage and the eighth stage. A film forming method characterized by maintaining the state.   12. The film forming method according to claim 1, wherein the film forming gas is silane.   13. The high-frequency discharge according to claim 1, wherein the high-frequency discharge is performed between parallel plate electrodes, and the deposition surface is disposed on the electrode side held at a ground potential. A film forming method. A first step of depositing a silicon film using a high frequency discharge while supplying a deposition gas;
A second stage in which the supply of the discharge gas is started at the same time as the stop of the supply of the film forming gas is started while the pressure in the chamber is kept constant while maintaining the high-frequency discharge;
A third stage of maintaining the high frequency discharge by continuing to supply the discharge gas after the supply of the film forming gas is stopped;
A fourth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
A fifth stage of crystallizing the deposited silicon film to form a crystalline silicon film;
A sixth step of patterning the crystalline silicon film;
A seventh step of forming a gate insulating film on the patterned crystalline silicon film;
An eighth step of forming a gate electrode on the gate insulating film,
A method for manufacturing a thin film transistor, characterized in that the time for maintaining the third stage is longer than the time for changing the atmosphere in the second stage. A first step of depositing a silicon film using a high frequency discharge while supplying a deposition gas;
A second stage in which the supply of hydrogen gas is started simultaneously with stopping the supply of the film forming gas while keeping the pressure in the chamber constant while maintaining the high frequency discharge;
A third stage of maintaining the high frequency discharge by continuing to supply the hydrogen gas after the supply of the film forming gas is stopped;
A fourth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
A fifth stage of crystallizing the deposited silicon film to form a crystalline silicon film;
A sixth step of patterning the crystalline silicon film;
A seventh step of forming a gate insulating film on the patterned crystalline silicon film;
An eighth step of forming a gate electrode on the gate insulating film,
A method for manufacturing a thin film transistor, characterized in that the time for maintaining the third stage is longer than the time for changing the atmosphere in the second stage. A first stage of supplying a discharge gas to start high frequency discharge;
A second stage in which the supply of the deposition gas is started at the same time as the supply of the discharge gas is started to be stopped while maintaining the high-frequency discharge;
A third step of forming a silicon film using high frequency discharge while supplying the film forming gas;
A fourth stage of starting supply of the discharge gas at the same time as stopping the supply of the film forming gas while keeping the pressure in the chamber constant while maintaining the high frequency discharge;
After the supply of the film-forming gas is stopped, the fifth stage of maintaining the high-frequency discharge by continuing to supply the discharge gas;
A sixth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
A seventh step of crystallizing the deposited silicon film to form a crystalline silicon film;
An eighth step of patterning the crystalline silicon film;
A ninth step of forming a gate insulating film on the patterned crystalline silicon film;
A tenth step of forming a gate electrode on the gate insulating film;
The method for manufacturing a thin film transistor is characterized in that the time for maintaining the fifth stage is longer than the time for changing the atmosphere in the fourth stage. A first stage of supplying hydrogen gas and starting high frequency discharge;
A second stage in which the supply of the film forming gas is started at the same time as the stop of the supply of the hydrogen gas is started while maintaining the high-frequency discharge;
A third step of forming a silicon film using high frequency discharge while supplying the film forming gas;
A fourth stage in which the supply of the hydrogen gas is started at the same time as the stop of the supply of the film forming gas while the pressure in the chamber is kept constant while maintaining the high frequency discharge;
A fifth stage of maintaining the high frequency discharge by continuing to supply the hydrogen gas after the supply of the film forming gas is stopped;
A sixth stage in which high-frequency discharge is stopped by decreasing the power stepwise or continuously;
A seventh step of crystallizing the deposited silicon film to form a crystalline silicon film;
An eighth step of patterning the crystalline silicon film;
A ninth step of forming a gate insulating film on the patterned crystalline silicon film;
A tenth step of forming a gate electrode on the gate insulating film;
The method for manufacturing a thin film transistor is characterized in that the time for maintaining the fifth stage is longer than the time for changing the atmosphere in the fourth stage.   16. The method for manufacturing a thin film transistor according to claim 14 or 15, wherein a self-bias is applied to the deposition surface in the second stage and the third stage.   18. The method for manufacturing a thin film transistor according to claim 16, wherein a self-bias is applied to the deposition surface in the fourth stage and the fifth stage.   20. The method for manufacturing a thin film transistor according to claim 14, wherein the deposition gas is silane.   21. The high frequency discharge according to claim 14, wherein the high frequency discharge is performed between parallel plate electrodes, and the film formation surface is disposed on an electrode side maintained at a ground potential. A method for manufacturing a thin film transistor.

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