JP2016153518A - Film deposition method and film deposition apparatus of carbon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition method of a carbon film that hardly causes reaction damage to a workpiece or a treatment chamber during production processing, even when chlorine gas is used for lowering thermal decomposition temperature in film deposition of a carbon film.SOLUTION: A film deposition method of a carbon film includes a step (step 2) for depositing a carbon film on the surface to be treated of a workpiece and a step for thermal treatment of the workpiece. In the step for depositing a carbon film, a hydrocarbon-based carbon source gas and chlorine gas for lowering thermal decomposition temperature of the hydrocarbon-based carbon source gas are supplied to the workpiece to deposit the carbon film on the surface to be treated of the workpiece at a temperature lower than the thermal decomposition temperature of the hydrocarbon-based carbon source gas itself. In the step for thermal treatment, the workpiece on which the carbon film is deposited is supplied with nitrogen gas, hydrogen gas, or a gas containing nitrogen and hydrogen to subject the workpiece on which the carbon film is deposited to thermal treatment at a temperature higher than the film deposition temperature.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a carbon film forming method and a film forming apparatus.

  Carbon (C) is attracting attention as one of the next-generation semiconductor materials. As a method for forming a carbon film, a plasma CVD method as described in Patent Document 1 or a thermal CVD method as described in Patent Document 2 is known.

  However, when a carbon film is formed using a plasma CVD method, the film forming temperature can be kept low (150 to 350 ° C. according to Patent Document 1), but the step coverage is not good. There is. For this reason, the film formation of the carbon film using the plasma CVD method is not suitable for the film formation on the base having the irregularities such as the line pattern and the hole pattern.

  In addition, when a carbon film is formed using a thermal CVD method, better step coverage can be obtained as compared with the plasma CVD method, but the film forming temperature is set to a high temperature (see Patent Document 2). According to the circumstances, it must be set to 800 to 1000 ° C. For this reason, the film formation of the carbon film using the thermal CVD method is not suitable for application to the process of the upper layer portion of the semiconductor device, for example, from the viewpoint of the thermal history of the transistor formed on the silicon wafer. There is.

  Therefore, as described in Patent Document 3, when forming a carbon film, by supplying a pyrolysis falling gas that lowers the pyrolysis temperature of the carbon source gas together with the hydrocarbon-based carbon source gas, Attempts have been made to form a carbon film at a temperature lower than that of the conventional thermal CVD method.

International Publication No. 2008/105321 JP 2012-17502 A JP 2014-33186 A

As described in Patent Document 3, a carbon film is formed while supplying a pyrolytic lowering gas that lowers the thermal decomposition temperature of the carbon source gas together with a hydrocarbon-based carbon source gas. A carbon film can be formed at a temperature lower than that in the thermal CVD method. One such pyrolysis falling gas is chlorine (Cl ₂ ) gas.

However, when Cl ₂ gas is used as the pyrolysis descending gas, there is a situation that chlorine is taken into the carbon film formed. Chlorine taken into the carbon film becomes Cl ₂ gas during the manufacturing process of a semiconductor device typified by, for example, an etching process or an ashing removal process, and is released again into the processing chamber. Cl ₂ gas is a kind of etching gas. For this reason, there is a concern that the Cl ₂ gas re-released and scattered into the processing chamber may cause reaction damage such as etching damage to the object to be processed in the manufacturing process, the inner wall of the processing chamber, and the structure in the processing chamber. Is done.

  The present invention is a carbon that can hardly cause reaction damage to an object to be processed or a processing chamber in a manufacturing process even when chlorine gas is used as a pyrolysis-falling gas for forming a carbon film. A film forming method and a film forming apparatus capable of performing the film forming method are provided.

  A carbon film forming method according to a first aspect of the present invention is a carbon film forming method for forming a carbon film on a surface to be processed of the object to be processed. (1) The object to be processed The hydrocarbon-based carbon source gas and a chlorine gas that lowers the thermal decomposition temperature of the hydrocarbon-based carbon source gas are supplied, and the film-forming temperature is set higher than the thermal decomposition temperature of the hydrocarbon-based carbon source gas itself. Forming the carbon film on the surface to be treated at a low temperature; and (2) nitrogen gas, hydrogen gas, or a gas containing nitrogen and hydrogen on the object to be treated on which the carbon film is formed. And heat-treating the object to be processed on which the carbon film has been formed with a heat treatment temperature equal to or higher than the film formation temperature.

  A film forming apparatus according to a second aspect of the present invention is a film forming apparatus for forming a carbon film on a surface to be processed of an object to be processed, the surface to be processed on which the carbon film is formed. A processing chamber for storing the target object, a processing gas supply mechanism for supplying a gas used for processing into the processing chamber, and a heating device for heating the target object stored in the processing chamber; The process gas supply mechanism, and a controller that controls the heating device, wherein the controller performs the carbon film formation method according to the first aspect, and the process gas supply mechanism, Control the heating device.

  According to the present invention, even when chlorine gas is used as a pyrolysis fall gas for forming a carbon film, it is possible to make it difficult to cause reaction damage to an object to be processed and a processing chamber during the manufacturing process. A carbon film forming method and a film forming apparatus capable of performing the film forming method can be provided.

The flowchart which shows an example of the sequence of the film-forming method of the carbon film which concerns on 1st Embodiment of this invention Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Diagram showing film composition of carbon film Sectional drawing which shows roughly an example of the vertical batch type film-forming apparatus which concerns on 2nd Embodiment of this invention Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device Sectional drawing which shows schematically the state of to-be-processed object in the manufacturing process of a semiconductor device

  Embodiments of the present invention will be described below with reference to the drawings. Note that common parts are denoted by common reference numerals throughout the drawings.

(First embodiment)
FIG. 1 is a flowchart showing an example of a sequence of a carbon film forming method according to the first embodiment of the present invention, and FIGS. 2A to 2C schematically show states of objects to be processed in the sequence shown in FIG. It is sectional drawing. 2A to 2C schematically show a processing chamber of the film forming apparatus.

  First, as shown in Step 1 of FIG. 1 and FIG. 2A, as an object to be processed, for example, a silicon wafer (hereinafter referred to as a wafer) 1 having a silicon oxide film 2 formed on its surface is used as a processing chamber 3 of a film forming apparatus. Carry in.

Next, as shown in Step 2 and FIG. 2B of FIG. 1, a hydrocarbon-based carbon source gas and chlorine (Cl ₂ ) gas are supplied to the processing chamber 3, and on the surface to be processed of the object to be processed, In the example, a carbon film 4 is formed on the silicon oxide film 2. Cl ₂ gas is a pyrolysis falling gas that lowers the pyrolysis temperature of the hydrocarbon-based carbon source gas. When the pyrolysis falling gas is not used, the deposition temperature of the carbon film 4 is approximately 800 to 1000 ° C. However, when a pyrolysis falling gas such as Cl ₂ gas is used, the deposition temperature of the carbon film 4 can be made lower than the pyrolysis temperature of the hydrocarbon-based carbon source gas alone without plasma assist. For example, the deposition temperature of the carbon film 4 may be in the range of about 300 ° C. or more and less than 600 ° C.

  In this example, in order to improve the step coverage, the carbon film 4 is formed by a non-plasma thermal CVD method.

As an example of hydrocarbon-based carbon source gas,
C _n H _{2n + 2}
C _m H _2m
C _m H _2m-2
And a gas containing a hydrocarbon represented by at least one molecular formula (wherein n is a natural number of 1 or more and m is a natural number of 2 or more).

The hydrocarbon-based carbon source gas includes
Benzene gas (C ₆ H ₆ )
May be included.

As the hydrocarbon represented by the molecular formula C _n H _{2n + 2} ,
Methane gas (CH ₄ )
Ethane gas (C ₂ H ₆ )
Propane gas (C ₃ H ₈ )
Butane gas (C ₄ H ₁₀ : includes other isomers)
Pentane gas (C ₅ H ₁₂ : includes other isomers)
And so on.

As the hydrocarbon represented by the molecular formula C _m H _2m ,
Ethylene gas (C ₂ H ₄ )
Propylene gas (C ₃ H ₆ : includes other isomers)
Butylene gas (C ₄ H ₈ : includes other isomers)
Pentene gas (C ₅ H ₁₀ : includes other isomers)
And so on.

As the hydrocarbon represented by the molecular formula C _m H _2m-2 ,
Acetylene gas (C ₂ H ₂ )
Propin gas (C ₃ H ₄ : includes other isomers)
Butadiene gas (C ₄ H ₆ : includes other isomers)
Isoprene gas (C ₅ H _8, including other isomers)
And so on.

In this example, C ₅ H ₈ gas was used as the hydrocarbon-based carbon source gas. An example of the processing conditions of step 2 is as follows.
C ₅ H ₈ gas flow rate: 100 sccm
Cl ₂ gas flow rate: 25sccm
Deposition temperature: 350 ° C
Processing pressure: 199.95 Pa (1.5 Torr)
Processing time: 180min
(In this specification, 1 Torr is defined as 133.3 Pa.)

  Under such processing conditions, a carbon film 4 having a thickness of about 20 nm is formed on the silicon oxide film 2. The state of the carbon film 4 is, for example, amorphous. The entire surface to be processed of the wafer 1 is covered with such a carbon film 4.

Next, as shown in Step 3 of FIG. 1 and FIG. 2C, after purging the inside of the processing chamber 3, an annealing gas such as nitrogen (N ₂ ) gas or hydrogen (H ₂ ) gas, or An object to be processed in which a carbon film 4 is formed by supplying a gas containing nitrogen and hydrogen, for example, ammonia (NH ₃ ) gas, and the entire surface to be processed of the wafer 1 is covered with the carbon film 4, in this example, a wafer 1 is heat-treated. The heat treatment temperature is preferably higher than the film formation temperature in the carbon film formation shown in Step 2. An example of the processing conditions of step 3 is as follows.
N ₂ gas flow rate: 1000 sccm or H ₂ gas flow rate: 1000 sccm or NH ₃ gas flow rate: 1000 sccm
Heat treatment temperature: 500 ° C
Processing pressure: 66.5 Pa (0.5 Torr)
Processing time: 45min

  When the heat treatment in Step 3 is completed, the film formation of the carbon film 4 using the carbon film formation method according to the first embodiment is completed.

FIG. 3 is a view showing the film composition of the carbon film 4. In FIG.
(a) No heat treatment in step 3 (no annealing)
(b) When the wafer 1 is transferred from the processing chamber 3 to the processing chamber of the heat treatment apparatus provided outside and the heat treatment of step 3 is performed using N ₂ gas in the processing chamber of the heat treatment apparatus (annealing ex− Situ 500 ° C. N ₂ )
(c) In the case where the wafer 1 is subjected to the heat treatment in step 3 using N ₂ gas in the processing chamber 3 of the film forming apparatus following the step 2 (annealing in-situ 500 ° C. N ₂ ).
(d) In the case where the wafer 1 is subjected to the heat treatment in Step 3 using H ₂ gas in the processing chamber 3 of the film formation apparatus following Step 2 (annealing in-situ 500 ° C. H ₂ ).
(e) In the case where the wafer 1 is subjected to the heat treatment in step 3 using NH ₃ gas in the processing chamber 3 of the film forming apparatus following the step 2 (annealing in-situ 500 ° C. NH ₃ ).
These five cases are shown.

  First, in the case of (a), the carbon film 4 contains about 12.6% of Cl atoms.

  On the other hand, in the cases (b) to (e), the Cl atoms in the carbon film 4 were reduced to about 2.0 to 5.0%. Specifically, in the case of (b), the Cl atoms in the carbon film 4 were reduced to about 5.0%, and in the case of (c), the Cl atoms in the carbon film 4 were reduced to about 4.4%.

  Further, from the results of (b) and (c), step 3 can be performed either in the processing chamber of the heat treatment apparatus provided outside the film forming apparatus or in the processing chamber of the film forming apparatus. However, it was found that the effect of reducing Cl atoms can be obtained.

Further, from the result of (d) and (e), the annealing gas used in step 3 is not limited to the N ₂ gas, even H ₂ gas and NH ₃ gas, the Cl atoms like the N ₂ gas It was found that a reduction effect can be obtained. Specifically, in the case of (d), the Cl atom in the carbon film 4 was reduced to about 3.9%, and in the case of (e), the Cl atom in the carbon film 4 was reduced to about 2.0%. As shown in (e), when NH ₃ gas is used, nitrogen atoms (N) are newly taken into the carbon film 4, but the carbon film 4 has no problem.

The specific film composition of the carbon film 4 is as follows.
(a) Carbon (C) 73.9% Hydrogen (H) 12.7% Chlorine (Cl) 12.6%
Oxygen (O) 0.8%
(b) Carbon (C) 79.2% Hydrogen (H) 11.3% Chlorine (Cl) 5.0%
Oxygen (O) 4.5%
(c) Carbon (C) 77.7% Hydrogen (H) 13.3% Chlorine (Cl) 4.4%
Oxygen (O) 4.6%
(d) Carbon (C) 78.0% Hydrogen (H) 13.9% Chlorine (Cl) 3.9%
Oxygen (O) 4.2%
(e) Carbon (C) 75.6% Hydrogen (H) 16.7% Chlorine (Cl) 2.0%
Oxygen (O) 2.9% Nitrogen (N) 2.8%

  The carbon film 4 contains a small amount of O atoms. These O atoms are absorbed in the atmospheric environment when being transported to the film forming apparatus, It is considered that it originates from O atoms contained in the silicon oxide film 2 existing on the processing surface. Further, it was observed that the content of O atoms in the carbon film 4 increased in the latter when the heat treatment in step 3 was not performed and in the case where the heat treatment in step 3 was performed. It can be considered that this is because the ratio of O atoms in the carbon film 4 was relatively increased because Cl atoms were removed from the carbon film 4 by the heat treatment in Step 3.

In the carbon film forming method according to the first embodiment, the carbon film 4 is supplied by supplying Cl ₂ gas together with the hydrocarbon-based carbon source gas, although it is a thermal CVD method that does not use plasma assist. The film is formed. Therefore, the carbon film 4 can be formed at a thermal decomposition temperature of the hydrocarbon-based carbon source gas itself, for example, at a film formation temperature as low as 350 ° C. less than 800 ° C.

  Therefore, first, according to the first embodiment, plasma assist is not used, the step coverage is good, and the carbon film can be formed at a temperature lower than that of the conventional thermal CVD method. A carbon film forming method is obtained.

Furthermore, according to the first embodiment, as shown in Step 3 in succession to the process of forming the carbon film 4, the processing chamber 3 contains N ₂ gas, H ₂ gas, or nitrogen and hydrogen. A gas, for example, NH ₃ gas is supplied, and the wafer 1 on which the carbon film 4 is formed is heat-treated. By this heat treatment, Cl atoms taken in the carbon film 4 at about 12 to 13% are re-emitted to the outside of the film. For this reason, the content of Cl atoms can be reduced in the carbon film 4 after the heat treatment.

According to the carbon film 4 in which the Cl atom content is reduced, the carbon film 4 is etched when the wafer 1 on which the carbon film 4 is formed is etched or when the carbon film 4 is removed by ashing. The advantage that Cl atoms re-released as Cl ₂ gas from the inside can be reduced can be obtained.

  The specific Cl atom content according to the first embodiment is in the range of about 2% or more and 5% or less as shown in (b) to (e) of FIG. If the Cl atom content in the carbon film 4 is in the range of about 2% or more and 5% or less, even if Cl atoms are re-released from the carbon film 4, the etching process or the ashing removal process is performed. It is possible to reduce the possibility of reaction damage such as etching damage to the wafer 1 in the manufacturing process, the inner wall of the processing chamber in which these steps are performed, and the structure in the processing chamber. Therefore, it is preferable that the heat treatment shown in Step 3 is performed under the condition that the Cl atom content in the carbon film 4 is in the range of 2% to 5%.

  The heat treatment shown in step 3 is preferably performed in a state where the entire surface to be processed of the wafer 1 is covered with the carbon film 4. By covering the entire surface to be processed of the wafer 1 with the carbon film 4, the surface to be processed of the wafer 1, that is, the structure in the manufacturing process is not exposed to the outside during the heat treatment. For this reason, even if Cl atoms are re-released from the carbon film 4, the possibility that the structure in the manufacturing process is affected by the re-released Cl atoms can be reduced.

  The heat treatment temperature in step 3 is preferably higher than the film formation temperature in the carbon film formation shown in step 2 as described above. Specifically, the deposition temperature of the carbon film 4 is not less than 300 ° C. and less than 600 ° C. Accordingly, the heat treatment temperature in step 3 is preferably set to a temperature exceeding 300 ° C. The upper limit of the heat treatment temperature in Step 3 is, for example, 600 ° C. or less. This is because if the temperature exceeds 600 ° C., the advantage of low-temperature film formation of the carbon film 4 tends to be impaired. It is preferable that the heat treatment temperature in Step 3 is appropriately selected to be higher than the film formation temperature in the range of more than 300 ° C. and 600 ° C. or less. However, it is desirable that the heat treatment temperature in step 3 is lowered as well as the film formation temperature in step 2. The upper limit of the heat treatment temperature is preferably kept as low as possible within a range that does not hinder the rerelease of Cl atoms. If an example from such a viewpoint is given, for example, if the film formation temperature in Step 2 is in the range of 300 ° C. to 400 ° C., the upper limit of the heat treatment temperature in Step 3 is 500 ° C. or less.

  Further, the carbon film formation shown in step 2 and the heat treatment shown in step 3 may be performed continuously in the processing chamber of the film forming apparatus as shown in FIGS. 2A to 2B. (In situ) As shown in FIG. 3B, step 2 is performed in the processing chamber of the film forming apparatus, and step 3 is performed in the processing chamber of the heat treatment apparatus provided separately from the film forming apparatus. Yes (ex situ). However, considering the waiting time until the temperature of the wafer 1 falls to the transferable temperature, the waiting time until the temperature of the processing chamber of the heat treatment apparatus rises to the heat treatment temperature, the transfer time from the film forming apparatus to the heat treatment apparatus, and the like, In-situ is more advantageous in terms of throughput than ex-situ.

The carbon film 4 which is formed at a low temperature by the Cl ₂ gas according to the first embodiment and the Cl atom content is controlled to be 2% or more and 5% or less, for example, in the processing chamber of the film forming apparatus. After film formation, the film can be transferred to another substrate processing apparatus, for example, an etching apparatus, and effectively used as a film to be etched in the processing chamber of the etching apparatus. Further, the film can be effectively used as a film which is transferred to the ashing apparatus and is removed by ashing in the processing chamber of the ashing apparatus.

  Of course, the carbon film 4 in which the content of Cl atoms is controlled to be, for example, 2% or more and 5% or less is continuously formed in the processing chamber of the same film forming apparatus after being formed by the film forming apparatus, for example, It can also be used effectively as a film to be etched. Furthermore, the film forming process of the carbon film 4 and the etching process of the carbon film 4 may be repeatedly performed in the processing chamber of the same film forming apparatus.

  As described above, according to the method for forming a carbon film according to the first embodiment, even when chlorine gas is used as the pyrolysis fall gas for forming the carbon film, the wafer 1 in the manufacturing process, It is possible to obtain an advantage that the carbon film 4 that hardly causes reaction damage such as etching damage to the inner wall of the processing chamber for processing the wafer 1 or the structure in the processing chamber can be obtained.

(Second Embodiment)
The second embodiment relates to an example of a film forming apparatus capable of performing the carbon film forming method according to the first embodiment.

  FIG. 4 is a sectional view schematically showing an example of a vertical batch type film forming apparatus according to the second embodiment of the present invention.

  As shown in FIG. 4, a vertical batch type film forming apparatus (hereinafter referred to as a film forming apparatus) 100 includes a cylindrical outer wall 101 having a ceiling and a cylindrical inner wall 102 provided inside the outer wall 101. ing. The outer wall 101 and the inner wall 102 are made of, for example, quartz, and the inner side of the inner wall 102 accommodates an object to be processed, in this example, a plurality of wafers 1. A processing chamber 3 is provided. Inside the processing chamber 3, the carbon film forming method described in the first embodiment is collectively performed on the plurality of wafers 1.

  The outer wall 101 and the inner wall 102 are separated from each other along the horizontal direction with the annular space 104 therebetween, and are joined to the base material 105 at the respective lower ends. The upper end portion of the inner wall 102 is separated from the ceiling portion of the outer wall 101, and the upper portion of the processing chamber 3 is communicated with the annular space 104. An annular space 104 communicating with the upper side of the processing chamber 3 serves as an exhaust path. The gas supplied and diffused into the processing chamber 3 flows from below the processing chamber 3 to above the processing chamber 3 and is sucked into the annular space 104. An exhaust pipe 106 is connected to, for example, a lower end portion of the annular space 104, and the exhaust pipe 106 is connected to an exhaust device 107. The exhaust device 107 includes a vacuum pump (not shown) and the like, and exhausts the gas used for the processing from the inside of the processing chamber 3 so that the pressure inside the processing chamber 3 becomes an appropriate pressure for the processing. Adjust.

  A heating device 108 is provided outside the outer wall 101 so as to surround the processing chamber 3. The heating device 108 adjusts the temperature inside the processing chamber 3 to a temperature suitable for processing, and heats the object to be processed, in this example, the plurality of wafers 1.

  A lower portion of the processing chamber 3 communicates with an opening 109 provided in the base material 105. For example, a manifold 110 formed in a cylindrical shape from stainless steel is connected to the opening 109 via a seal member 111 such as an O-ring. A lower end portion of the manifold 110 is an opening, and the boat 112 is inserted into the processing chamber 3 through the opening. The boat 112 is made of, for example, quartz and has a plurality of support columns 113. A groove (not shown) is formed in the support column 113, and a plurality of substrates to be processed are supported at once by the groove. Thereby, the boat 112 can mount a plurality of, for example, 50 to 150, wafers 1 as multiple substrates to be processed. By inserting the boat 112 on which the plurality of wafers 1 are placed into the processing chamber 3, the plurality of wafers 1 can be accommodated in the processing chamber 3.

  The boat 112 is placed on the table 115 through a quartz heat insulating cylinder 114. The table 115 is supported on a rotating shaft 117 that penetrates a lid portion 116 made of, for example, stainless steel. The lid 116 opens and closes the opening at the lower end of the manifold 110. For example, a magnetic fluid seal 118 is provided in the penetrating portion of the lid portion 116, and rotatably supports the rotating shaft 117 while hermetically sealing the rotating shaft 117. Further, a seal member 119 made of, for example, an O-ring is interposed between the peripheral part of the lid part 116 and the lower end part of the manifold 110 to maintain the sealing performance inside the processing chamber 3. The rotating shaft 117 is attached to the tip of the arm 120 supported by an elevating mechanism (not shown) such as a boat elevator, for example. As a result, the wafer boat 112, the lid 116, and the like are integrally moved up and down in the vertical direction and are inserted into and removed from the processing chamber 3.

  The film forming apparatus 100 includes a processing gas supply mechanism 130 for supplying a gas used for processing inside the processing chamber 3.

The processing gas supply mechanism 130 of this example includes a hydrocarbon-based carbon source gas supply source 131a, a Cl ₂ gas supply source 131b, an inert gas supply source 131c, and an annealing gas supply source 131d. In this example, C ₅ H ₈ gas is hydrocarbon-based carbon source gas, N ₂ gas is an inert gas, the annealing gas N ₂ gas, or H ₂ gas, or NH ₃ gas is used Yes. The inert gas can be used as a purge gas used for purging before and after Step 2 and Step 3 or as a dilution gas in Step 2. Further, the N ₂ gas as the inert gas, when the user selects the N ₂ gas as the annealing gas is summarized gas supply source to a respective one, so as to share a gas supply source in an inert gas and the annealing gas May be.

The hydrocarbon-based carbon source gas supply source 131a is connected to the gas supply port 134a via a flow rate controller (MFC) 132a and an on-off valve 133a. Similarly, the Cl ₂ gas supply source 131b is connected to the gas supply port 134b via the flow rate controller (MFC) 132b and the on-off valve 133b, and the inert gas supply source 131c is connected to the flow rate controller (MFC) 132c and the on-off valve 133c. Is connected to the gas supply port 134c. The annealing gas supply source 131d is connected to the gas supply port 134d through a flow rate controller (MFC) 132d and an on-off valve 133d. Each of the gas supply ports 134 a to 134 d is provided so as to penetrate the side wall of the manifold 110 along the horizontal direction, and diffuses the supplied gas toward the inside of the processing chamber 3 above the manifold 110.

  A controller 150 is connected to the film forming apparatus 100. The control unit 150 includes a process controller 151 including, for example, a microprocessor (computer), and the process controller 151 controls each component of the film forming apparatus 100. A user interface 152 and a storage unit 153 are connected to the process controller 151.

  The user interface 152 includes an input unit including a touch panel display and a keyboard for an operator to perform command input operations in order to manage the film forming apparatus 100, and a display that visualizes and displays the operating status of the film forming apparatus 100. Etc. are provided.

  The storage unit 153 is a control program for realizing various processes executed by the film forming apparatus 100 under the control of the process controller 151 and causes each component of the film forming apparatus 100 to execute processes according to the processing conditions. A so-called process recipe including the following programs is stored. The process recipe is stored in a storage medium in the storage unit 153. The storage medium may be a hard disk or a semiconductor memory, or a portable medium such as a CD-ROM, DVD, or flash memory. Further, the process recipe may be appropriately transmitted from another apparatus via, for example, a dedicated line.

  The process recipe is read from the storage unit 153 according to an operator's instruction or the like from the user interface 152 as necessary, and the process controller 151 executes processing according to the read process recipe, thereby forming the film forming apparatus. 100 executes the requested processing under the control of the process controller 151. In this example, the film forming apparatus 100 executes processing according to the carbon film forming method described in the first embodiment under the control of the process controller 151.

  The carbon film forming method according to the first embodiment can be implemented by, for example, a vertical batch type film forming apparatus 100 as shown in FIG.

(Third embodiment)
The third embodiment relates to an application example suitable for a carbon film formed according to the carbon film forming method according to the first embodiment. This application example is an example of a carbon film that is used for forming a vertically long deep hole or groove having a large aspect ratio, for example, an aspect ratio of “5” or more.

  5A to 5H are cross-sectional views schematically showing the state of the object to be processed during the manufacturing process of the semiconductor device.

  First, as shown in FIG. 5A, a silicon oxide film 2 is formed on the wafer 1, and a hard mask layer 5 is formed on the silicon oxide film 2. The hard mask layer 5 is formed using, for example, a photolithography method, and includes a window 6 corresponding to the designed aperture pattern or groove pattern. Using the hard mask layer 5 as a mask, the silicon oxide film 2 is anisotropically etched using, for example, the RIE method, and a recess 7 corresponding to the window 6 is formed on the surface of the silicon oxide film 2. Form.

  Next, as shown in FIG. 5B, the surface of the silicon oxide film 2 in which the hard mask layer 5 and the recesses 7 are formed is used as a processing surface, and the carbon film according to the first embodiment is formed on the processing surface. In accordance with the film forming method, a carbon film 4-1 that thinly covers the entire surface to be processed is formed.

  Next, as shown in FIGS. 5C to 5D, the silicon oxide film 2 is anisotropically etched using, for example, the RIE method using the hard mask layer 5 as a mask. At this time, as shown in FIG. 5C, the carbon film 4-1 that thinly covers the entire surface to be processed is etched at the beginning of anisotropic etching, as shown in FIG. 5C. (FIG. 5C), the portion that exists in the direction perpendicular to the surface to be processed remains on the side surfaces of the window 6 and the recess 7 in a side wall shape. By continuing the anisotropic etching, the anisotropic etching proceeds with respect to the silicon oxide film 2, and the recess 7 becomes deeper. Eventually, as shown in FIG. 5D, the carbon thin film 4-1 remaining in the side wall shape on the side surfaces of the window 6 and the recess 7 is also etched and disappears. This anisotropic etching step is performed, for example, in a processing chamber of an anisotropic etching apparatus provided separately from the carbon film forming apparatus. Of course, both film forming and anisotropic etching can be performed. Any substrate processing apparatus may be performed in the same processing chamber.

  Next, when the carbon film 4-1 disappears, as shown in FIG. 5E, the surface of the silicon oxide film 2 on which the hard mask layer 5 and the recesses 7 are formed is used as a processing surface again. In addition, according to the carbon film forming method according to the first embodiment, a carbon film 4-2 that covers the entire surface to be thin is formed.

  Next, as shown in FIGS. 5F to 5G, the silicon oxide film 2 is anisotropically etched using, for example, the RIE method using the hard mask layer 5 as a mask. Also in this case, as in the carbon film 4-1, the carbon film 4-2 has a portion in the shape of a side wall that is perpendicular to the surface to be processed (FIG. 5F). The carbon thin film 4-2 remaining in the shape also disappears (FIG. 5G).

  As described above, by repeating the formation of the carbon thin film and the anisotropic etching with respect to the surface to be processed, as shown in FIG. 5H, the aspect ratio is large, and the vertically long and deep recesses 7 are formed in the silicon oxide film 2. Formed.

  When the deep recess 7 is to be formed in this way, if anisotropic etching is performed at once, the cross-sectional shape of the recess 7 becomes “bowed” (this phenomenon is hereinafter referred to as “bowing”). ). In order to suppress the occurrence of such “bowing”, the thin carbon film 4-1 is coated, and when the thin carbon film 4-1 disappears, the thin carbon film 4-2 is coated again. By repeating the formation of such a carbon film and anisotropic etching on the surface to be processed, it is possible to suppress the side surface of the recess 7 from being etched excessively, and the recess 7 having a substantially vertical side surface shape. Can be formed in the silicon oxide film 2.

In the method of manufacturing a semiconductor device including the step of forming the recess 7, every time the thin carbon film 4-1 or 4-2 is etched and disappears, Cl atoms are re-released as Cl ₂ gas from the film. It will be done. The re-released Cl ₂ gas may cause reaction damage such as etching damage to the exposed surface of the silicon oxide film 2 or the hard mask layer 5 during the manufacturing process. Even if the re-released Cl ₂ gas is a very small amount, for example, it may have a great influence on a semiconductor device having a structure miniaturized to “1” μm or less.

On the other hand, even if the carbon film forming method according to the first embodiment is a carbon film formed at low temperature using Cl ₂ gas, the Cl content in the film is, for example, 2% or more. It can be controlled to 5% or less. For this reason, the re-released Cl ₂ gas can be reduced to ½ or less compared with the case where the heat treatment in Step 3 is not performed. Such a carbon film forming method is useful, for example, as a carbon film forming method used for manufacturing a semiconductor device having a structure miniaturized to “1” μm or less.

  As mentioned above, although this invention was demonstrated according to 1st-3rd embodiment, this invention is not limited to the said 1st-3rd embodiment, A various deformation | transformation is possible in the range which does not deviate from the meaning. is there.

  For example, in the above embodiment, the processing conditions are specifically exemplified, but the processing conditions are not limited to the above specific examples.

  In the above embodiment, an example of forming a carbon film using a vertical batch type film forming apparatus has been shown. Of course, it is possible to use a single wafer type film forming apparatus, and a batch type other than the vertical type. It is also possible to use a film forming apparatus. In particular, when the carbon film formation and the anisotropic etching are performed in the same processing chamber, a single wafer type film forming apparatus or a batch type film forming apparatus other than the vertical type is preferably selected.

  In addition, the present invention can be variously modified without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Silicon oxide film, 3 ... Processing chamber, 4, 4-1, 4-2 ... Carbon film, 5 ... Hard mask layer, 6 ... Window, 7 ... Recessed part

Claims (13)

A carbon film forming method for forming a carbon film on a surface to be processed of a target object,
(1) A hydrocarbon-based carbon source gas and a chlorine gas that lowers the thermal decomposition temperature of the hydrocarbon-based carbon source gas are supplied to the object to be processed, and the film-forming temperature is set to the hydrocarbon-based carbon source gas. Forming the carbon film on the surface to be treated as a temperature lower than its own thermal decomposition temperature;
(2) Nitrogen gas, hydrogen gas, or a gas containing nitrogen and hydrogen is supplied to the object to be processed on which the carbon film has been formed, and the carbon film is formed with a heat treatment temperature equal to or higher than the film formation temperature. Heat treating the processed object, and
A method of forming a carbon film, comprising:   2. The carbon film according to claim 1, wherein a temperature lower than a thermal decomposition temperature of the hydrocarbon-based carbon source gas itself is selected within a range of 300 ° C. or more and less than 600 ° C. Film forming method.   3. The carbon film forming method according to claim 1, wherein a temperature higher than the film forming temperature is selected from a range of 300 ° C. to 600 ° C. .   The carbon film formation according to any one of claims 1 to 3, wherein the step (2) is performed in a state where the entire surface to be processed is covered with the carbon film. Method.   5. The carbon according to claim 1, wherein the carbon film is a film that is etched or ashed in a processing chamber of a substrate processing apparatus different from the film forming apparatus. A film forming method.   5. The carbon film forming method according to claim 1, wherein the carbon film is a film that is etched after film formation in a processing chamber of the film forming apparatus. .   The film formation of a carbon film according to any one of claims 1 to 4, wherein the carbon film is a film in which film formation and etching are repeated in a processing chamber of the film formation apparatus. Method.   8. The step (2) is performed under a condition in which a chlorine content in the carbon film is in a range of 2% or more and 5% or less. Carbon film formation method. The film formation temperature is a temperature lower than the thermal decomposition temperature in the absence of plasma assist of the hydrocarbon-based carbon source gas alone,
9. The carbon film forming method according to claim 1, wherein the carbon film is formed by a non-plasma thermal CVD method. The hydrocarbon-based carbon source gas is
C _n H _{2n + 2}
C _m H _2m
C _m H _2m-2
10. A gas containing a hydrocarbon represented by at least one molecular formula of (wherein n is a natural number of 1 or more and m is a natural number of 2 or more). A method for forming a carbon film as described in 1.   11. The carbon film forming method according to claim 1, wherein the step (1) and the step (2) are continuously performed in a processing chamber of a film forming apparatus. .   The step (1) is performed in a processing chamber of a film forming apparatus, and the step (2) is performed in a processing chamber of a heat treatment apparatus provided separately from the film forming apparatus. Item 11. The carbon film forming method according to any one of Items 10 to 10. A film forming apparatus for forming a carbon film on a surface to be processed of an object to be processed,
A processing chamber containing the object to be processed having the surface to be processed on which the carbon film is formed;
A processing gas supply mechanism for supplying a gas used for processing into the processing chamber;
A heating device for heating the object to be processed accommodated in the processing chamber;
A controller for controlling the processing gas supply mechanism and the heating device,
The controller controls the processing gas supply mechanism and the heating device so that the carbon film forming method according to any one of claims 1 to 11 is performed. Membrane device.

Images