JP3702235B2 - Method for removing silicon deposited film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for removing a silicon deposition film generated in an apparatus such as a plasma CVD apparatus in an apparatus for generating plasma by applying high-frequency power to electrodes to form a silicon film on a target substrate.
[0002]
[Prior art]
  A general configuration of a plasma CVD apparatus will be described with reference to FIGS. 8 and 9 as an example of an apparatus for generating a plasma by applying high-frequency power to electrodes to form a silicon film on a target substrate. FIG. 8 is a schematic configuration diagram of the plasma CVD apparatus, and FIG. 9 is a cross-sectional arrangement view in the vacuum vessel of the plasma CVD apparatus as seen in the direction of arrows AA in FIG.
[0003]
  As shown in FIG. 8, the plasma CVD apparatus 100 is provided with the electrode 3 in the vacuum vessel 1 and, as shown in FIG. 9, the silicon film is formed on the ground electrode 12 provided facing the electrode 3. A substrate 7 is arranged. A film forming chamber 2 is formed on the opposite side of the electrode 3 from the substrate 7 so as to surround the electrode 3. The film forming chamber 2 has a shape in which the substrate 7 side is opened, and a gas supply unit 10 connected to a gas supply source (not shown) is provided on the surface facing the electrode 3. Further, the vacuum vessel 1 is provided with an exhaust pipe 11 for discharging gas, and is connected to an exhaust device (vacuum device) (not shown).
[0004]
  Note that the gas supply unit 10 is not limited to that shown in FIG. 8, and the electrode 3 itself is a gas pipe, and there is a gas supply unit 10 that ejects gas from a plurality of ejection holes provided in the gas pipe.
[0005]
  In the plasma CVD apparatus 100, since the substrate 7 is used for solar cells, thin film transistors, and the like, amorphous silicon or the like is formed. However, in recent years, there is a high demand for large size, and the silicon film is uniformly formed on the large size substrate 7. Therefore, the electrode 3 is also formed in a planar shape facing the substrate 7 and is increased in size.
[0006]
  Further, as shown in FIG. 8, the electrodes 3 configured in a planar shape are connected in parallel by connecting two lateral electrode rods 3a and 3b disposed at opposite end portions thereof and connecting them in parallel. Ladder electrodes formed in a vertical lattice shape with the arranged vertical electrode rods 3c are often used.
[0007]
  Although there is one in which one high-frequency power source is connected to the electrode 3, in the case of the ladder electrode 3 having a large size, two high-frequency power sources are often connected.
[0008]
  In this case, in the example of FIG. 8, the upper lateral electrode rod 3a (first lateral electrode rod) is connected to the feeder line A5a via a plurality of upper feeder points 6a (first feeder points). The electric wire A5a is connected to an RF amplifier A4a (first high frequency power supply) which is a high frequency power source, and the lower lateral electrode bar 3b (second lateral electrode bar) is connected to a plurality of lower feeding points 6b (second second power source). A power supply line B5b is connected via a power supply point), and the power supply line B5b is connected to an RF amplifier B4b (second high-frequency power supply) that is a high-frequency power supply.
[0009]
  In this specification, “vertical direction”, “horizontal direction”, “upper side”, and “lower side” are referred to in the state shown in FIG. 8 in order to explain the mutual direction and position of each part in this specification. However, the arrangement direction of the actual plasma CVD apparatus 100, the vacuum vessel 1, the electrode 3 and the like is not specified. This is the same in the description of the embodiment of the present invention based on FIGS.
[0010]
  In the amorphous silicon film formation using the plasma CVD apparatus 100 as described above, the substrate 7 is set and the inside of the vacuum vessel 1 is evacuated, and then the silane gas (SiH) is supplied from the gas supply unit 10._Four) Is passed through the electrode 3 and flows toward the substrate 7. RF power is supplied from the RF amplifier A 4 a and RF amplifier A 4 b to the electrode 3, for example, with a high frequency power of an RF frequency of 60 MHz, and the silane gas is turned into plasma to form silicon (Si ) On the substrate 7. The film formation chamber 2 has a function of suppressing the flow of silane gas to the opposite side of the electrode 3 and improving the efficiency of film formation.
[0011]
  However, while the amorphous silicon film or the like is continuously formed, a silicon film is deposited on the inner wall of the vacuum vessel 1 and further falls, or silicon powder is generated in the gas phase, and these silicons are generated. If the powder adheres to the substrate 7 during film formation, a problem of defective products occurs. In addition, the silicon deposited film is also generated on the electrode 3 itself, which causes problems such as a decrease in output and nonuniformity of plasma generation distribution.
[0012]
  Therefore, the silicon deposited film is removed. As a general method, the members such as the electrode 3 are disassembled, washed with alkali, and reassembled. However, the number of man-hours for decomposition, alkali cleaning, drying, and reassembly is large, and during that time, the plasma CVD apparatus 100 has to stop operating, and there has been a problem that the cost and operating rate are reduced.
[0013]
  On the other hand, as a self-cleaning process capable of increasing the operating rate of the plasma CVD apparatus 100, the film forming operation of the plasma CVD apparatus 100 is temporarily stopped, and NF that becomes a reactive etching gas in the vacuum vessel 1 is used._Three(Nitrogen trifluoride) is injected, and high frequency power is applied to the electrode 3 for film formation in the same manner, and NF_ThreeThe plasma is decomposed into plasma, and the inside of the vacuum vessel 1 is etched by F (fluorine) radicals generated by the decomposition, and the silicon film or silicon powder is converted into SiF as follows._FourA method of vaporizing and removing (silicon fluoride) is also considered.
[0014]
        F radical + Si → SiF_Four(Silicon fluoride: Boiling point -95.5 ° C)
  This reaction is an exothermic reaction. If there is no more Si to be removed, the temperature will no longer rise, and the temperature will drop accordingly. Therefore, it will be used as information for detecting the completion of cleaning and can be used as an automatic method for removing a silicon deposition film. It has been.
[0015]
  However, even in this case, conventionally, if the electrode 3 is relatively small (for example, 500 mm square or less), the NF_ThreeAlthough plasma could be generated uniformly, the temperature of the electrode 3 increased rapidly, and corrosion of the electrode 3 member due to over-etching (a metal portion on the surface corroded by F radicals) was a problem.
[0016]
  In the case of the electrode 3 having a large area exceeding 500 mm square, NF_ThreeBecause it is difficult to generate plasma uniformly, remote plasma (NF in another location)_ThreeIt is necessary to use etching by generating plasma and performing etching by introducing a gas containing F radicals having a relatively long lifetime to the electrode portion.
[0017]
  In remote plasma, however, the upstream portion of the F radical-containing gas has a high F radical concentration and a high etching rate, and the downstream side has a low F radical concentration and a low etching rate. This causes a corrosion problem of the electrode 3 member. In addition, since the F radical-containing gas is routed, there is a restriction that a material with low F resistance cannot be used in each part of the process.
[0018]
[Problems to be solved by the invention]
  The present invention provides a uniform silicon deposition film on a large-area electrode in the removal of a silicon deposition film in an apparatus for producing a silicon film on a target substrate by generating a plasma by applying high frequency power to such a conventional electrode. Silicon deposition that enables etching and plasma generation that can suppress over-etching due to overheating of the electrode member due to plasma, and enables self-cleaning process that can suppress electrode member corrosion due to over-etching even if etching distribution difference occurs It is an object of the present invention to provide a film removal method.
[0019]
[Means for Solving the Problems]
  (1) The present invention has been made to solve the above problems, and as a first means thereof, NF is contained in the vacuum vessel._ThreeAnd applying high frequency power to the planar electrode in the same vacuum vessel, NF_ThreeIn the silicon deposition film removal method, in which the silicon deposition film in the vacuum vessel is removed by the generated F radicals, first and second feeding points are respectively provided at opposing edge portions of the electrode. The first and second high frequency power sources are connected to the first and second feeding points, respectively, and the frequency of the high frequency power of the first and second high frequency power sources is the same and the phase shift is within a certain range. A central plasma mode in which plasma is mainly generated in a central portion between the first feeding point and the second feeding point; and a frequency of the high-frequency power of the first and second high-frequency power sourcesBy providing a difference over a certain rangeThere is provided a silicon deposited film removing method characterized by alternately performing an upper and lower plasma mode in which plasma is mainly generated in the vicinity of the first feeding point and the second feeding point.
[0020]
  According to the first means, plasma is generated uniformly on a time average over the entire electrode, and the silicon deposited film of the entire electrode is uniformly etched and removed while suppressing overheating of the electrode. Since the plasma is generated uniformly, the entire inside of the vacuum vessel is also removed uniformly and uniformly.The
[0021]
(2) As a second means, NF is placed in the vacuum vessel. _Three And applying high frequency power to the planar electrode in the same vacuum vessel, NF _Three In the silicon deposition film removal method, in which the silicon deposition film in the vacuum vessel is removed by the generated F radicals, first and second feeding points are respectively provided at opposing edge portions of the electrode. The first and second high frequency power sources are connected to the first and second feeding points, respectively, and the frequency of the high frequency power of the first and second high frequency power sources is the same and the phase shift is within a certain range. The central plasma mode in which plasma is mainly generated in the central portion between the first feeding point and the second feeding point, and the frequency of the high-frequency power of the first and second high-frequency power sources are the same and the phase is shifted. The upper and lower plasma modes in which plasma is mainly generated in the vicinity of the first feeding point and the second feeding point with a certain range or more are alternately performed, and the central plasma mode and the upper and lower plasma modes are alternately performed. Providing a silicon deposition film removing method characterized by providing an interval for stopping the supply of the high-frequency power between the de.
  Also by the second means, the plasma is generated uniformly on the entire electrode on a time average basis, and the silicon deposited film of the entire electrode is uniformly etched and removed while suppressing overheating of the electrode. Because the plasma is generated uniformly, the entire inside of the vacuum vessel is also removed uniformly and uniformly.,furtherBy adjusting the time ratio of the interval, the heating amount can be adjusted, and the etching can proceed within an appropriate temperature range.
  (3No.3As a means of1In the silicon deposited film removing method of the above means, there is provided a silicon deposited film removing method characterized in that an interval for stopping the supply of high-frequency power is provided between the central plasma mode and the upper and lower plasma modes.
  First3According to the means1In addition to the action of the above means, the amount of heating can be adjusted by adjusting the time ratio of the interval, and the etching can proceed within an appropriate temperature range.
[0022]
  (4) Also,4As the means, the first means to the first3In the silicon deposited film removing method according to any one of the means, the silicon deposited film removing method is characterized in that a plurality of the first and second feeding points are provided.
[0023]
  First4According to the means, the first means to the first3In addition to the action of any of the means, the distribution of plasma generation can be made more uniform.
[0024]
  (5No.5As the means, the first means to the first3In the silicon deposited film removal method according to any one of the means, the planarly configured electrode is provided with a first lateral electrode rod provided with the first feeding point and the second feeding point. A method for removing a silicon deposited film, comprising: a second horizontal electrode bar formed on the first electrode and a plurality of vertical electrode bars connected between the first and second horizontal electrode bars. To do.
[0025]
  First5According to the means, the first means to the first3The effect of any one of the above means is exhibited in a ladder electrode effective as a large-sized electrode.
[0026]
  (6No.6As the means, the first means to the first3In the silicon deposited film removal method according to any one of the above means, the central plasma mode periodically changes the phase shift of the high-frequency power of the first and second high-frequency power sources over the positive and negative values within the predetermined range. A method for removing a silicon deposited film is provided.
[0027]
  First6According to the means, the first means to the first3In addition to the action of either of the means, the peak of plasma intensity periodically oscillates in the central portion between the first and second feeding points, and the distribution of plasma generation can be made more uniform.
[0028]
  (7No.7As a means of2Means or number3In the method for removing a silicon deposited film of the above means, the center plasma mode and the upper and lower plasma modes are alternately performed, and then the inside of the vacuum vessel is cooled, and thereafter, the time ratio of the interval is set to the cooling inside the vacuum vessel. There is provided a silicon deposition film removing method characterized in that the center plasma mode and the upper and lower plasma modes are alternately performed in an increased manner as compared with the previous one.
[0029]
  First7According to the means2Means or number3In addition to the action of the above means, when the silicon deposition film is thick, first adjust the temperature to be relatively high while increasing the etching action to advance the etching quickly, and after cooling, increase the time ratio of the interval. Etching can proceed to prevent over-etching at a relatively low temperature.
[0030]
  (8No.8As the means, the first means to the first7The silicon deposited film removing method according to any one of the above means is characterized in that the planar electrode is an electrode for forming a film in the vacuum vessel.
[0031]
  First8According to the means, the first means to the first7In addition to the action of any of the above means, the electrode for film-forming can be used as it is in the film-forming apparatus, the man-hour increase is small, the influence of the operation stop on the film-forming process is extremely small, and the safe and efficient self-cleaning. Process can be done.
[0032]
  (9No.9As a means of8In the silicon deposited film removing method of the above means, the silicon deposited film removing method is characterized in that the vacuum vessel constitutes a plasma CVD apparatus.
[0033]
  First9According to the means8In addition to the function of the above means, the operating rate is improved in the plasma CVD apparatus, and the inside of the vacuum vessel and the electrode can be appropriately cleaned.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
  A silicon deposited film removal method according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory view of an embodiment of the silicon deposited film removing method of the present embodiment, and is a schematic configuration diagram of a plasma CVD apparatus. 2 is an explanatory view of the plasma generation mode in the electrode of FIG. 1, FIG. 3 is an explanatory view of the central plasma mode in FIG. 2, FIG. 4 is an explanatory view of the upper and lower plasma modes in FIG. 2, and FIG. FIG. 6 is an explanatory diagram of the electrode temperature control operation in the silicon deposited film removing method of the present embodiment, and FIG. 7 is the silicon deposition of the present embodiment. It is a value table of one Example of the film | membrane removal method.
[0035]
  As shown in FIG. 1, the apparatus configuration of the plasma CVD apparatus 200 of this embodiment is the same as that of the conventional apparatus described in FIG. 8 except that the phase control signal source 8 is connected to the RF amplifier A4a and the RF amplifier B4b. The configuration is the same as that of the plasma CVD apparatus example, and the cross section shown in FIG. 9 is also the same, so the illustration is omitted. To do.
[0036]
  In FIG. 1, 8 is a phase control signal source, its output A8a is input to the RF amplifier A4a via the external input terminal A9a, and output B8b is input to the RF amplifier B4b via the external input terminal B9b. The high frequency phase shift θ of the high frequency power output from the amplifiers 8a and 8b and the mutual relationship between the RF frequencies fa and fb are controlled.
[0037]
  The silicon deposited film removing method according to the present embodiment is NF in the vacuum vessel 1 as described in the conventional example._Three, Applying high frequency power to the electrode 3 for film formation, and NF_ThreeIn the method in which the silicon deposition film in the vacuum vessel 1 is etched by F radicals, and the silicon is vaporized and removed as silicon fluoride by F radicals, as shown in FIG. Plasma is mainly generated in the center between the upper feeding point 6a and the lower feeding point 6b (the central region X, the upper central upper region Xa and the lower central lower region Xb in FIG. 2). “Central plasma mode” (in this specification, “central plasma mode” is used for that purpose), and as shown in FIG. 2B, in the vicinity of the upper feeding point 6a of the electrode 3 (the upper end in FIG. 2). Area Ya) and “upper and lower plasma mode” in which plasma is mainly generated in the vicinity of the lower feeding point 6b (lower end area Yb in FIG. 2) (in this specification, “upper and lower plasma mode” means Use) To control the phase control signal source 8 so as to emerge alternately, as a result, time-averaged uniform plasma over the entire electrode 3 so as to generate. By providing a plurality of upper feeding points 6a and lower feeding points 6b for the electrode 3, the distribution of plasma generation in the lateral direction can be made more uniform, and a larger size electrode can be dealt with.
[0048]
  The “central plasma mode” will be described with reference to FIG. 3. In the plasma CVD apparatus 200 configured as shown in FIG. 1, the phase shift signal source 8 controls the phase shift θ of the high frequency power of the RF amplifier A4a and the RF amplifier B4b. By this phase modulation method, the upper and lower voltage distributions at the electrode 3, that is, the distribution of the plasma intensity P are controlled.
[0039]
  When the RF frequency fa of the RF amplifier A4a and the RF frequency fb of the RF amplifier B4b are the same frequency, for example, 60 MHz, and there is no phase shift θ between the two high frequencies, as shown in FIG. It becomes the highest distribution in area X.
[0040]
  The RF frequencies fa and fb of 60 MHz are specifications set in the film forming process, but the high-frequency power of the RF amplifier A4a and RF amplifier B4b can be used as it is for etching for removing the silicon deposited layer.
[0041]
  When the high frequency on the RF frequency fb side has an angle phase shift −θ within a certain range with respect to the RF frequency fa side, as shown in FIG. The highest distribution. Here, as an example of the phase shift angle (modulation angle) θ within a certain range, θ≈40 °.
[0042]
  Conversely, when the high frequency on the RF frequency fb side has a phase shift angle of + θ (θ≈40 °) with respect to the RF frequency fa side, the plasma intensity P becomes the center as shown in FIG. The distribution is highest in the upper area Xa.
[0043]
  Therefore, the output A8a and the output B8b of the phase control signal source 8 are input to the RF amplifier A4a and the RF amplifier B4b, respectively, and the phase shift θ is within a certain range by the phase modulation method, for example, over −40 ° to + 40 °. When the period is periodically changed with the oscillation period Tf, a peak fluctuation F of the plasma intensity P occurs in the period Tf between the center upper area Xa and the center lower area Xb. Between the region Xa and the lower center region Xb, plasma is generated strongly uniformly on a time average, and a “central plasma mode” is formed.
[0044]
  As an example of the oscillation period Tf, Tf≈10 sec. However, the oscillation period Tf and the phase shift angle θ are higher in the center between the upper and lower feeding points 6a and 6b, that is, the center area X shown in the figure. It is set so that plasma is uniformly generated on the time average between the area Xa and the lower central area Xb. If the plasma is generated substantially uniformly in the central portion between the upper and lower feed points 6a and 6b only in the central region X, the phase shift angle θ can be reduced or zero to suppress the fluctuation F of the peak of the plasma intensity P. Good.
[0045]
  On the other hand, in the “upper and lower plasma mode”, as shown in FIG. 4, the phase shift angle (modulation angle) θ is further increased to a certain range or more, so that the peak of the plasma intensity P is increased to the upper end region Ya and the lower end region Yb. Is generated.
[0046]
  As the phase shift angle θ of a certain range or more, for example, θ is set to 100 ° or more (preferably about 115 °), and when the RF frequency fb side has a phase shift ± θ with respect to the RF frequency fa side in FIG. As shown in a), the plasma intensity P has the highest distribution in the upper end area Ya and the lower end area Yb shown in the vicinity of the upper and lower feed points 6a and 6b, and the distribution around the central area X becomes lower. A “plasma mode” is formed. In this case, there is a characteristic that the plasma tends to concentrate on the upper and lower power feeding points 6a and 6b, and the “upper and lower plasma mode” utilizes the characteristic.
[0047]
  In addition, as shown in FIG. 4B, the “upper and lower plasma mode” is set so that the RF frequency fb has a frequency difference ± Δfb over a certain range with respect to the RF frequency fa, instead of the phase shift θ. For example, when fa = 60 MHz, Δfb≈1.5 MHz, and fb = fa−Δfb≈58.5 MHxz, the “upper and lower plasma mode” is formed. In this case, Δfb / fa is 2.5%.
[0048]
  When the “center plasma mode” and the “upper and lower plasma mode” are alternately formed as described above, the plasma is generated uniformly on the time average on the entire electrode 3, and the silicon deposited film on the entire electrode 3 is uniformly uniform. Etched away. In addition, since the plasma is uniformly generated in the entire electrode 3, the entire inside of the vacuum vessel 1 can be removed uniformly and uniformly.
[0049]
  In addition to the above effects, according to the silicon deposited film removal method of the present embodiment, overheating of the electrode 3 is suppressed, and over-etching due to overheating is prevented. FIG. 5 shows the time elapse of the high temperature cleaning for removing the silicon deposited film, the electrode temperature Tc at the center of the electrode 3 (between the center upper region Xa and the center lower region Xb) and the lower feed point 6b of the electrode 3. The relationship of the electrode temperature Tb of the vicinity (lower end area Yb) is shown.
[0050]
  In the silicon deposited film removal method of the present embodiment, when the silicon deposited film is thick, the high temperature cleaning is performed so that the etching action is advanced while the temperature is adjusted to about 300 to 400 ° C. to improve the etching action. , Stop the plasma before the metal surface comes out, NF_ThreeGas or N₂It is effective in terms of efficiency and prevention of over-etching to cool to about 150 ° C. by flowing a gas or the like, and then to perform low-temperature cleaning in which etching proceeds while adjusting the temperature to about 200 to 250 ° C. FIG. Is an example of such high temperature cleaning.
[0051]
  As shown in the temperature history example of the electrode 3 in FIG. 5, both the electrode temperature Tc and the electrode temperature Tb can be stopped within a substantially constant range, although there is a tendency to increase gradually. The rise is suppressed by about 300 ° C.
[0052]
  This is because, in the silicon deposited film removal method of the present embodiment, the “central plasma mode” and the “upper and lower plasma mode” are alternately performed, and therefore the upper end region Ya and the lower end region Yb are heated in the “central plasma mode”. This is because in the “upper and lower plasma mode”, the heating from the central upper region Xa to the central lower region Xb is weakened.
[0053]
  Further, when switching between the “central plasma mode” and the “upper and lower plasma mode”, an interval for stopping the supply of high-frequency power is provided, and the heating amount can be adjusted by the time ratio of the interval.
[0054]
  As a result, overheating of the electrode 3 that may occur when continuously heated can be prevented, overaging of the electrode 3 due to overheating can be prevented, and etching can proceed within an appropriate temperature range. Thus, thermal deformation and damage of the structure such as the film forming chamber 2 can be prevented.
[0055]
  The switching between the “central plasma mode” and the “upper and lower plasma mode” is shown in FIG._CAnd plasma intensity P in “upper and lower plasma mode”_AFor example, the plasma ON time t in the “central plasma mode”_C= 3 minutes, interval time t_I= 1 minute, “ON / OFF plasma mode” plasma ON time t_A= 3 minutes, interval time t_I= 1 minute.
[0056]
  Each plasma ON time t_C, T_A, Interval time t_ITherefore, the amount of heating can be adjusted, so that it is possible to set the temperature for high temperature cleaning and low temperature cleaning, and to suppress the temperature increase over time.
[0057]
  If the temperature of the electrode 3 member rises even if it is controlled in this way, even if the electrode metal is exposed, the rapid increase in the electrode temperature is suppressed, so the corrosion rate is slow. Since the corrosion amount of the member is small (in the conventional case, the temperature rises to about 500 ° C., and the corrosion amount may be 10 times or more that of the present invention), the plasma is stopped once and the NF_ThreeGas or N₂By flowing gas or the like to lower the entire film forming chamber 2 to about 100 to 150 ° C. and performing etching with plasma again, cleaning can be performed while suppressing the corrosion rate.
[0058]
  FIG. 7 shows various values of an example of the silicon deposited film removal method of the present embodiment. In this embodiment, RF frequency fa, fb = 60 MHz, central plasma mode: phase shift θ = ± 40 °, upper and lower plasma mode: phase shift θ = ± 100 ° or more, plasma ON time total 162 minutes, cleaning including intervals In a total time of 334 minutes, the results were obtained that there was no corrosion, the remaining film, and a small amount in a part, and the silicon deposited film in the entire vacuum chamber could be substantially removed.
[0059]
  Therefore, according to the silicon deposited film removal method of the present embodiment, the electrode for film formation can be used as it is in the film forming apparatus, the additional equipment cost is small, the man-hour is small, the operation stop for the film forming process, etc. The impact is extremely small. In addition, since over-etching of the electrode can be prevented, a safe and efficient self-cleaning process is possible.
[0060]
  In particular, in the plasma CVD apparatus of the embodiment, the operating rate is improved, and the inside of the vacuum vessel and the electrode can be appropriately cleaned, so that the yield and quality of the film-forming product such as amorphous silicon film can be improved. .
[0061]
  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications may be made to the specific configuration within the scope of the present invention.
[0062]
  For example, the electrode 3 has been described by exemplifying a ladder electrode. However, the electrode 3 is not limited thereto, and may be a flat plate that faces the substrate and is connected to a high frequency power source at two opposite sides. The present invention can be similarly applied to electrodes and the like.
[0063]
【The invention's effect】
  (1) According to the first aspect of the present invention, there is provided a method for removing a silicon deposited film in an NF in a vacuum vessel._ThreeAnd applying high frequency power to the planar electrode in the same vacuum vessel, NF_ThreeIn the silicon deposition film removal method, in which the silicon deposition film in the vacuum vessel is removed by the generated F radicals, first and second feeding points are respectively provided at opposing edge portions of the electrode. The first and second high frequency power sources are connected to the first and second feeding points, respectively, and the frequency of the high frequency power of the first and second high frequency power sources is the same and the phase shift is within a certain range. A central plasma mode in which plasma is mainly generated in a central portion between the first feeding point and the second feeding point; and a frequency of the high-frequency power of the first and second high-frequency power sourcesBy providing a difference over a certain rangeSince the upper and lower plasma modes in which the plasma is mainly generated in the vicinity of the first feeding point and the second feeding point are alternately performed, the plasma is generated uniformly on a time average over the entire electrode. The silicon deposited film on the entire electrode is uniformly etched and removed, and the plasma is generated uniformly on the entire electrode, so that the entire inside of the vacuum vessel can be removed uniformly. It becomes possible.
[0064]
  (2) According to the invention of claim 2, NF is contained in the vacuum vessel._ThreeAnd applying high frequency power to the planar electrode in the same vacuum vessel, NF_ThreeIn the silicon deposition film removal method, in which the silicon deposition film in the vacuum vessel is removed by the generated F radicals, first and second feeding points are respectively provided at opposing edge portions of the electrode. The first and second high frequency power sources are connected to the first and second feeding points, respectively, and the frequency of the high frequency power of the first and second high frequency power sources is the same and the phase shift is within a certain range. A central plasma mode in which plasma is mainly generated in a central portion between the first feeding point and the second feeding point; and a frequency of the high-frequency power of the first and second high-frequency power sourcesWith the same phase shift above a certain rangeThe upper and lower plasma modes in which plasma is mainly generated in the vicinity of the first feeding point and the second feeding point are alternately performed.In addition, an interval for stopping the supply of high-frequency power is provided between the central plasma mode and the upper and lower plasma modes.Since the plasma is generated uniformly on the entire electrode on a time average basis, the silicon deposition film on the entire electrode is uniformly etched and removed, and the plasma is generated uniformly on the entire electrode. The entire inside of the vacuum vessel can be removed uniformly and uniformly.And moreBy adjusting the time ratio of the interval, the amount of heating can be adjusted, electrode overheating that may occur when continuously heated can be prevented, and overetching of the electrode due to overheating can be prevented, Etching can proceed within an appropriate temperature range, and thermal deformation and damage of the structure in the vacuum vessel can be prevented.
  (3Claim3According to the invention of claim1In the method for removing a silicon deposited film according to claim 1, an interval for stopping the supply of high-frequency power is provided between the central plasma mode and the upper and lower plasma modes.1In addition to the effect of the invention, by adjusting the time ratio of the interval, the amount of heating can be adjusted, and overheating of the electrode that may occur when continuously heated is prevented, and over-etching of the electrode due to overheating is prevented. It can be prevented and etching can proceed within an appropriate temperature range, and thermal deformation and damage of the structure in the vacuum vessel can be prevented.
[0065]
  (4Claim4According to the invention, claims 1 to3The method for removing a silicon deposited film according to any one of claims 1 to 3, wherein a plurality of the first and second feeding points are provided.3In addition to the effect of any one of the inventions, the distribution of plasma generation can be made more uniform, and a larger electrode can be dealt with.
[0066]
  (5Claim5According to the invention, claims 1 to3In the silicon deposited film removal method according to any one of the above, the planarly configured electrode is provided with a first lateral electrode rod provided with the first feeding point and the second feeding point. Since the second horizontal electrode rod and the plurality of vertical electrode rods connecting between the first and second horizontal electrode rods are provided, the first to second claims are provided.3The effect of any one of the inventions can be achieved in a ladder electrode effective as a large-sized electrode.
[0067]
  (6Claim6According to the invention, claims 1 to3In the silicon deposited film removal method according to any one of the above, the center plasma mode is configured to periodically change the phase shift of the high-frequency power of the first and second high-frequency power sources over the predetermined range in the positive and negative directions. Since constituted, claims 1 to3In addition to the effect of any one of the inventions, the plasma intensity peak periodically oscillates in the center between the first and second feeding points, the distribution of plasma generation can be made more uniform, and the size can be increased. It can cope with the electrode.
[0068]
  (7Claim7According to the invention of claim2Or claims3In the method for removing a silicon deposited film according to claim 1, after the center plasma mode and the upper and lower plasma modes are alternately performed, the inside of the vacuum vessel is cooled, and thereafter, the time ratio of the interval is set to the cooling inside the vacuum vessel. The center plasma mode and the upper and lower plasma modes are alternately configured to be increased compared to before, so that2Or claims3In addition to the effect of the present invention, when the silicon deposited film is thick, the etching action is first advanced by adjusting it so that it becomes relatively high temperature, and the etching proceeds quickly, and after cooling, the time ratio of the interval is increased. By allowing the etching to proceed at a relatively low temperature, the efficiency is improved and over-etching is prevented.
[0069]
  (8Claim8According to the invention, claims 1 to7The method for removing a silicon deposited film according to any one of claims 1 to 4, wherein the planar electrode is configured to be an electrode for film formation in the vacuum vessel.7In addition to the effect of any one of the inventions, the electrode for film formation can be used as it is in the film forming apparatus, the additional equipment cost is small, the number of man-hours is small, and the influence of the operation stoppage on the film forming process is extremely small. In addition, since over-etching of the electrode can be prevented, a safe and efficient self-cleaning process is possible.
[0070]
  (9Claim9According to the invention of claim8In the method for removing a silicon deposited film according to claim 1, the vacuum vessel constitutes a plasma CVD apparatus.8In addition to the effects of the invention, in the plasma CVD apparatus, the operating rate is improved, and the inside of the vacuum vessel and the electrode can be appropriately cleaned, so that the yield and quality of the film-forming product such as amorphous silicon film are improved. Is obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment of a silicon deposited film removal method according to an embodiment of the present invention, and is a schematic configuration diagram of a plasma CVD apparatus.
FIG. 2 is an explanatory diagram of a plasma generation mode in the electrode of FIG.
FIG. 3 is an explanatory diagram of the central plasma mode in FIG. 2;
4 is an explanatory diagram of an upper and lower plasma mode in FIG. 2. FIG.
FIG. 5 is a graph of electrode temperature history during high-temperature cleaning in the silicon deposited film removal method of the present embodiment.
FIG. 6 is an explanatory diagram of an electrode temperature control operation in the silicon deposited film removal method of the present embodiment.
FIG. 7 is a value table of an example of the silicon deposited film removing method of the present embodiment.
FIG. 8 is a general schematic diagram of a plasma CVD apparatus.
9 is a cross-sectional arrangement view in the vacuum vessel of the plasma CVD apparatus as viewed in the direction of arrows AA in FIG. 8;
[Explanation of symbols]
  1 Vacuum container
  2 Film forming room
  3 electrodes
  3a, 3b Lateral electrode rod
  3c Longitudinal electrode rod
  4a RF amplifier A
  4b RF amplifier B
  5a Feed line A
  5b Feed line B
  6a Upper feed point
  6b Lower feed point
  7 Substrate
  8 Phase control signal source
  10 Gas supply section
  11 Exhaust pipe
  12 Earth electrode
  100, 200 Plasma CVD apparatus

Claims (9)

Introducing NF ₃ into the vacuum container, by applying a high-frequency power to electrodes arranged in a planar same vacuum chamber, decomposing into plasma a NF _3, silicon in the same vacuum chamber by the generated F radicals In the silicon deposited film removing method for removing a deposited film, first and second feeding points are respectively provided at opposing edge portions of the electrode, and the first and second feeding points are respectively provided at the first and second feeding points. A high-frequency power source is connected, the frequency of the high-frequency power of the first and second high-frequency power sources is the same, and the phase shift is within a certain range, in the central portion between the first feeding point and the second feeding point By providing a difference of a certain range or more between the central plasma mode in which plasma is mainly generated and the frequency of the high-frequency power of the first and second high-frequency power sources, the vicinity of the first feeding point and the second feeding point In the upper and lower processes where plasma is mainly generated A method of removing a silicon deposited film, wherein the laser mode is alternately performed. NF ₃ is introduced into the vacuum vessel, high frequency power is applied to the planar electrode in the vacuum vessel, NF ₃ is turned into plasma and decomposed, and silicon deposits in the vacuum vessel are generated by the generated F radicals. In the silicon deposited film removing method for removing a film, first and second feeding points are respectively provided at opposing edge portions of the electrode, and first and second high-frequency points are provided at the first and second feeding points, respectively. A power source is connected, and the frequency of the high-frequency power of the first and second high-frequency power sources is the same and the phase shift is within a certain range, so that the main portion is centrally located between the first and second feeding points. The central plasma mode in which plasma is generated and the frequency of the high-frequency power of the first and second high-frequency power sources are the same and the phase shift is a certain range or more and the vicinity of the first and second feed points Mainly plasma is generated in A method for removing a silicon deposited film, wherein upper and lower plasma modes are alternately performed, and an interval for stopping supply of high-frequency power is provided between the central plasma mode and the upper and lower plasma modes. 2. The silicon deposited film removing method according to claim 1 , wherein an interval for stopping the supply of high-frequency power is provided between the central plasma mode and the upper and lower plasma modes. In silicon deposition film removing method according to any one of claims 1 to 3, wherein the first, silicon deposition film removing method characterized in that the second feeding point providing a plurality respectively. In silicon deposition film removing method according to any one of claims 1 to 3, electrodes configured to the planar is the first and the lateral electrode rod in which the first feeding point is provided, wherein A second lateral electrode rod provided with a second feeding point and a plurality of longitudinal electrode rods connecting the first and second lateral electrode rods. Silicon deposition film removal method. In silicon deposition film removing method according to any one of claims 1 to 3, wherein the central plasma mode, over the positive and negative first, the deviation of the second high-frequency power supply of the RF power of the phase within the predetermined range A method for removing a silicon deposited film, wherein the method is periodically changed. 4. The silicon deposited film removal method according to claim 2 or 3 , wherein after the center plasma mode and the upper and lower plasma modes are alternately performed, the inside of the vacuum vessel is cooled, and thereafter the time ratio of the interval The method for removing a silicon deposited film is characterized in that the central plasma mode and the upper and lower plasma modes are alternately performed by increasing the ratio of the vacuum chamber before cooling. In silicon deposition film removing method according to any one of claims 1 to 7, electrodes configured to the planar is silicon deposition, wherein said an electrode for performing the film in a vacuum chamber Film removal method. 9. The silicon deposited film removing method according to claim 8 , wherein the vacuum vessel constitutes a plasma CVD apparatus.

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