Film forming method and film forming apparatus

Abstract

To selectively form a film on a metal film of a substrate on whose surface a metal film and an insulation film are exposed without providing a mask.SOLUTION: With a film formation method, a film is selectively formed. The film formation method includes a cooling step and a film formation step. In the cooling step, a metal film and an insulation film are exposed on a surface, and a substrate supported in a chamber is cooled to a temperature at which molecules of a c-C4F8 gas and a SF6 gas condense on a surface of the substrate. In the film formation step, a processing gas containing the c-C4F8 gas and the SF6 gas is supplied into the chamber, the surface of the substrate is excited, and a carbon-containing film is formed on the metal film.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a film forming method and a film forming apparatus. [Background technology]

[0002] Patent document 1 proposes a technique for depositing a layer on a substrate by treating the reaction space surface with a treatment chemical to inactivate the reaction space surface against reaction with a plurality of deposition reactants, and then exposing the substrate to the plurality of reactants. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2007-501902 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for selectively forming a film on a metal film of a substrate having an exposed surface on which the metal film and an insulating film are formed, without providing a mask. [Means for solving the problem]

[0005] A film forming method according to an embodiment of the present disclosure selectively forms a film. The film forming method includes a cooling step and a film forming step. In the cooling step, a substrate with a metal film and an insulating film exposed on its surface and supported in a chamber is cooled to a temperature at which molecules of c-C4F8 gas and SF6 gas condense on the surface of the substrate. In the film forming step, a process gas containing c-C4F8 gas and SF6 gas is supplied into the chamber and the surface of the substrate is excited to form a carbon-containing film on the metal film. Effect of the Invention

[0006] According to the present disclosure, a film can be selectively formed on a metal film of a substrate having an exposed surface on which the metal film and insulating film are formed, without providing a mask. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a schematic configuration of a film forming apparatus according to an embodiment. [Figure 2A] FIG. 2A is a diagram showing an example of a processing result of a first film forming process according to the embodiment. [Figure 2B] FIG. 2B is a diagram showing an example of a processing result of the first film forming process according to the embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of a processing result of the second film forming process according to the embodiment. [Figure 4A] FIG. 4A is a diagram showing an example of a processing result of the third film forming process according to the embodiment. [Figure 4B] FIG. 4B is a diagram showing an example of a processing result of the third film forming process according to the embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of a processing result of the fourth film forming process according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of a manufacturing process for a semiconductor device. [Figure 7] FIG. 7 is a flowchart showing an example of the flow of the film forming method according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of a film formation method and a film formation apparatus disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed film formation method and film formation apparatus are not limited to the embodiment.

[0009] [Embodiment] An embodiment will be described. First, an example of a film formation apparatus for carrying out the film formation method of the present disclosure will be described. FIG. 1 is a cross-sectional view showing an example of a schematic configuration of a film formation apparatus 100 according to an embodiment. The film formation apparatus 100 shown in FIG. 1 includes a chamber 101, a stage 102, a gas supply mechanism 103, an exhaust mechanism 104, an excitation mechanism 105, and a control unit 150.

[0010] The chamber 101 is formed of a metal material such as aluminum or an alloy thereof. The chamber 101 accommodates a substrate W such as a semiconductor wafer on which a film is to be formed. A stage 102 is provided inside the chamber 101. The substrate W is placed on the stage 102.

[0011] The gas supply mechanism 103 and the excitation mechanism 105 are provided on a top plate of the chamber 101. The gas supply mechanism 103 supplies various gases used in the film formation process into the chamber 101. For example, the gas supply mechanism 103 supplies perfluorocarbon gas (PFC gas) such as c-C4F8 gas or SF6 gas into the chamber 101 as a process gas used in the film formation process.

[0012] The excitation mechanism 105 applies energy to the substrate W to excite the surface of the substrate W. For example, the excitation mechanism 105 is provided with a discharge tube, and generates a discharge of a rare gas (He gas, Ar gas, etc.), H2 gas, N2 gas, etc. in the discharge tube to generate low-energy electrons (Ek≦200 eV), metastable excited species of the rare gas (He*, Ar*, etc.), or H atoms or N atoms, which are irradiated onto the substrate W to excite the surface of the substrate W. The gas supply mechanism 103 and the excitation mechanism 105 may be provided on a side wall of the chamber 101.

[0013] An opening is provided in a side wall of the chamber 101, and an exhaust device 104 is provided via an exhaust pipe 111 connected to the opening. The exhaust device 104 includes a gate valve 112, a molecular turbo pump 113, and an auxiliary exhaust pump 114. The inside of the chamber 101 is exhausted via the exhaust pipe 111 by the molecular turbo pump 113 and the auxiliary exhaust pump 114 of the exhaust device 104. The pressure inside the chamber 101 is controlled by the gate valve 112 of the exhaust device 104.

[0014] The stage 102 is made of a metal material, for example, oxygen-free copper (Cu). The substrate W is placed on the upper surface of the stage 102. The stage 102 supports the placed substrate W. The stage 102 is supported by a support member 120 extending upward from the center of the bottom of the chamber 101.

[0015] Although not shown, the stage 102 and the support member 120 are provided with a cooling unit for cooling the substrate W. The cooling unit includes a cooling mechanism such as oxygen-free copper (Cu) or a cryostat, and cools the stage 102 to cool the substrate W via the stage 102. The stage 102 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the stage 102 and the substrate W. Note that the surfaces of the stage 102 and the support member 120 are preferably gold (Au) or chrome plated to prevent the input of radiant heat from the surroundings.

[0016] The operation of the film forming apparatus 100 configured as above is generally controlled by a control unit 150. To the control unit 150, a user interface 151 and a storage unit 152 are connected.

[0017] The user interface 151 is composed of an operation unit such as a keyboard through which a process manager inputs commands to manage the film forming apparatus 100, and a display unit such as a display that visualizes and displays the operating status of the film forming apparatus 100. The user interface 151 accepts various operations. For example, the user interface 151 accepts a predetermined operation to instruct the start of plasma processing.

[0018] The storage unit 152 is a storage device that stores various data. For example, the storage unit 152 is a storage device such as a hard disk, a solid state drive (SSD), an optical disk, etc. Note that the storage unit 152 may be a semiconductor memory in which data can be rewritten, such as a random access memory (RAM), a flash memory, or a non-volatile static random access memory (NVSRAM).

[0019] The storage unit 152 stores an OS (Operating System) and various recipes executed by the control unit 150. For example, the storage unit 152 stores various recipes including a recipe for executing a film formation process of a film formation method described below. Furthermore, the storage unit 152 stores various data used in the recipes. The programs and data may be stored in a computer-readable computer recording medium (e.g., a hard disk, a CD, a flexible disk, a semiconductor memory, etc.). Alternatively, the programs and data may be transmitted from another device at any time via, for example, a dedicated line and used online.

[0020] The control unit 150 is a device that controls the film forming apparatus 100. The control unit 150 may be an electronic circuit such as a central processing unit (CPU) or a micro processing unit (MPU), or an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The control unit 150 has an internal memory for storing programs that define various processing procedures and control data, and executes various processes using these.

[0021] The control unit 150 controls each part of the film forming apparatus 100. For example, the control unit 150 controls each part of the film forming apparatus 100 to perform a film forming process according to a recipe of recipe data stored in the storage unit 152. In the film forming apparatus 100, a substrate W on which a film is to be formed is placed on a stage 102. The substrate W on which a film is to be formed has a metal film and an insulating film exposed on its surface. For example, a copper (Cu) film as the metal film and a SiO2 film as the insulating film are formed on the substrate W, and the Cu film and the SiO2 film are exposed on its surface.

[0022] The film forming apparatus 100 performs a film forming process on the substrate W placed on the stage 102. For example, the film forming apparatus 100 uses a cooling unit to cool the substrate W placed on the stage 102 to a temperature at which molecules of c-C4F8 gas and SF6 gas condense on the surface of the substrate W. For example, the film forming apparatus 100 cools the substrate W to a temperature of 120 [K] or less. In this embodiment, for example, the substrate W is cooled to 80 [K].

[0023] The film forming apparatus 100 is configured to reduce the pressure in the chamber 101 by the exhaust device 104. -3 In this embodiment, the pressure in the chamber 101 is reduced to 10 -4 Reduce pressure to [Torr].

[0024] The film forming apparatus 100 supplies various gases used in the film forming process from the gas supply mechanism 103 into the chamber 101, activates rare gases (He, Ar, etc.), H2 gas, N2 gas, etc. from the excitation mechanism 105 using discharge plasma, etc., and irradiates the substrate W with the generated low-energy electrons, metastable excited species of rare gases (He*, Ar*, etc.), or H atoms and N atoms to excite the surface of the substrate W, thereby forming a film. For example, the film forming apparatus 100 supplies process gases including c-C4F8 gas and SF6 gas from the gas supply mechanism 103 into the chamber 101, and excites the surface of the substrate W by the excitation mechanism 105 to form an amorphous carbon film containing fluorine (hereinafter abbreviated as aC:F film) as a carbon-containing film on a metal film. The types and flow rates of gases supplied as process gases are, for example, as follows.

[0025] ·Processing gas c-C4F8 gas: 0.001 to 100 [sccm] (preferably 0.01 to 1 [sccm]) SF6 gas: 0.001 to 100 [sccm] (preferably 0.01 to 1 [sccm])

[0026] The processing gas is CF4, C2F6, C3F8, C6F instead of c-C4F8 gas. 14 (C n F 2n+2 ), perfluorocarbon gas such as C6F6 may be used, and NF3 gas may be used instead of SF6 gas.

[0027] Here, the results of film formation when the ratio of c-C4F8 gas and SF6 gas contained in the process gas is changed in the film formation process of the film formation method according to this embodiment will be described.

[0028] First, the result of the first film formation process will be described. In the first film formation process, a process gas containing 100% SF6 gas and a ratio of c-C4F8 gas and SF6 gas was changed for a substrate W having an exposed SiO2 film on its surface, and a film was formed by exciting the surface of the substrate W. FIG. 2A is a diagram showing an example of the process result of the first film formation process according to the embodiment. FIG. 2A shows absorbance for each wave number at each timing of immediately after the start of the first film formation process (0 min) and 2 minutes (2 min), 4 minutes (4 min), 6 minutes (6 min), 8 minutes (8 min), and 10 minutes (10 min) during the first film formation process. FIG. 2A shows, for example, a time change of an infrared absorption spectrum obtained by an infrared spectrophotometer with a transmission window provided in the chamber 101. At 1070 cm of the infrared absorption spectrum, -1 The waveform around 1070 cm corresponds to the SiO2 component. -1The waveform in the vicinity of the peak decreases with the passage of processing time. From this, when SF6 gas is 100%, the SiO2 film of the substrate W is etched. FIG. 2B is a diagram showing an example of a processing result of the first film formation processing according to the embodiment. FIG. 2B shows the processing time of the first film formation processing on the substrate W and the change in the film thickness of the SiO2 film exposed on the surface of the substrate W. As shown in FIG. 2B, the film thickness of the SiO2 film decreases with the passage of processing time, and the SiO2 film is etched.

[0029] Next, the result of the second film formation process will be described. In the second film formation process, a process gas containing 100% c-C4F8 gas and SF6 gas was supplied into the chamber 101 with a different ratio to a substrate W having an exposed SiO2 film on its surface, and the surface of the substrate W was excited to form a film. FIG. 3 is a diagram showing an example of the process result of the second film formation process according to the embodiment. FIG. 3 shows absorbance for each wave number at 0 min immediately after the start of the second film formation process and at 2 min, 4 min, 6 min, 8 min, and 10 min during the second film formation process. In the infrared absorption spectrum, the 1100-1400 cm -1 The waveform in the vicinity of 1100-1400 cm corresponds to the absorption due to the vibrational mode of CF-based amorphous carbon (CFx (x = 1-3)) containing fluorine. As shown in Figure 3, -1 The waveform around this point increases with the passage of processing time. This shows that when the c-C4F8 gas is 100%, a CF-based film such as amorphous carbon is formed on the SiO2 film of the substrate W.

[0030] Next, the result of the third film formation process will be described. In the third film formation process, a process gas in which the ratio of c-C4F8 gas and SF6 gas was changed to 1:1 (50% each) was supplied into the chamber 101 for a substrate W having an exposed SiO2 film on its surface, and the surface of the substrate W was excited to form a film. FIG. 4A is a diagram showing an example of the process result of the third film formation process according to the embodiment. FIG. 4A shows absorbance for each wave number at 0 min immediately after the start of the third film formation process and at 2 min, 4 min, 6 min, 8 min, and 10 min during the third film formation process. -1 The waveform around 1070 cm corresponds to the SiO2 component. -1 The waveform in the vicinity of the peak decreases with the passage of processing time. From this, when the ratio of c-C4F8 gas and SF6 gas is 1:1, the SiO2 film of the substrate W is etched. FIG. 4B is a diagram showing an example of a processing result of the third film formation process according to the embodiment. FIG. 4B shows the processing time of the third film formation process on the substrate W and the change in the film thickness of the SiO2 film exposed on the surface of the substrate W. As shown in FIG. 4B, the film thickness of the SiO2 film decreases with the passage of processing time, and the SiO2 film is etched.

[0031] Next, the results of the fourth film formation process will be described. In the fourth film formation process, the ratio of c-C4F8 gas and SF6 gas was changed to 1:1 (50% each) of c-C4F8 gas and SF6 gas, and a process gas was supplied into the chamber 101 and the surface of the substrate W was excited to form a film on the substrate W having a Cu film exposed on its surface. FIG. 5 shows the absorbance for each wave number at 0 min immediately after the start of the fourth film formation process and at 2 min, 4 min, 6 min, 8 min, and 10 min during the fourth film formation process. -1The waveform in the vicinity of 1100 to 1400 cm corresponds to the absorption due to the vibrational mode of CF-based amorphous carbon (CFx (x = 1 to 3)) containing fluorine. -1 The waveform around this point increases with the passage of processing time. This shows that when the ratio of c-C4F8 gas and SF6 gas is 1:1 (50% each), a CF-based film such as amorphous carbon is formed on the Cu film on the substrate W.

[0032] From the results of the third and fourth film formation processes shown in FIG. 4A, FIG. 4B, and FIG. 5, when the ratio of c-C4F8 gas and SF6 gas contained in the process gas is 1:1, a CF-based film such as amorphous carbon is formed on the Cu film of the substrate W. Meanwhile, the SiO2 film of the substrate W is etched. From this, when the ratio of c-C4F8 gas and SF6 gas contained in the process gas is 1:1, a film can be selectively formed on the Cu film of the substrate W with the Cu film and the SiO2 film exposed on the surface without providing a mask. In the film formation process of the film formation method according to the embodiment, by setting the ratio of c-C4F8 gas and SF6 gas contained in the process gas to 1:3 to 3:1, a film can be selectively formed on the Cu film of the substrate W without providing a mask.

[0033] Next, an example of a manufacturing process of a semiconductor device using the film formation process of the film formation method according to the embodiment will be described. FIG. 6 is a diagram for explaining an example of a manufacturing process of a semiconductor device. In FIG. 6, (A) to (E) are diagrams showing a schematic diagram of a change in the substrate W in each process. In FIG. 6(A), a Cu film 200 and a SiO2 film 201 exposed on the surface of the substrate W are shown. By the film formation process of the film formation method according to the embodiment, an aC:F film 202 is selectively formed on the Cu film 200 of the substrate W (FIG. 6(B)). This aC:F film 202 is used as a process block during film formation in the next process. For example, a second insulating film 203 is formed on the substrate W using the aC:F film 202 as a block layer (FIG. 6(C)). For example, after the film forming apparatus 100 forms the aC:F film 202, the gas supply mechanism 103 supplies the source gas of the insulating film into the chamber 101, and the second insulating film 203 is formed on the SiO2 film 201 using the aC:F film 202 as a mask. At this time, the insulating film 203 is slightly deposited on the aC:F film 202 as well. Next, a block layer removal process is performed on the substrate W to remove the aC:F film 202 that served as a block layer from the substrate W (FIG. 6(D)). This exposes the Cu film 200. Next, a process of embedding the wiring layer 204 with metal is performed on the substrate W (FIG. 6(E)). In this way, by selectively forming a film on the Cu film 200 of the substrate W by the film forming process of the film forming method according to the embodiment, the steps shown in FIG. 6(A) to (E) can be realized.

[0034] Next, a process operation for performing the film formation process of the film formation method according to the embodiment will be described below. Fig. 7 is a flow chart showing an example of the flow of the film formation method according to the embodiment.

[0035] In the film forming apparatus 100, a substrate W with a metal film and an insulating film exposed on its surface is placed on a stage 102 (S10). For example, a substrate W with a Cu film and a SiO2 film exposed on its surface is placed on the stage 102.

[0036] In the film forming apparatus 100, the substrate W is cooled (S11) to a temperature at which molecules of the c-C4F8 gas and the SF6 gas condense on the surface of the substrate W. For example, the substrate W is cooled to 80 [K].

[0037] In the film forming apparatus 100, a process gas containing c-C4F8 gas and SF6 gas is supplied from the gas supply mechanism 103 into the chamber 101, and the surface of the substrate W is excited by the excitation mechanism 105 to form a carbon-containing film on the metal film (S12). The process of S12 is performed for a processing time to obtain a required film thickness, and then the process is terminated.

[0038] As a result, the film formation apparatus 100 according to this embodiment can selectively form a film on the metal film of the substrate W in which the metal film and the insulating film are exposed on the surface, without providing a mask.

[0039] In the above embodiment, the excitation mechanism 105 activates a rare gas (He, Ar, etc.), H2 gas, N2 gas, or the like using discharge plasma, and supplies the generated slow electrons, metastable excited species of the rare gas (He*, Ar*, etc.), or H atoms or N atoms into the chamber 101 to provide energy to the substrate W and excite the surface of the substrate W. However, the present invention is not limited to this. The excitation mechanism 105 may have an ultraviolet ray source that generates ultraviolet rays, and may irradiate the substrate W with ultraviolet rays generated by the ultraviolet ray source to provide energy to the substrate W and excite the surface of the substrate W. The excitation mechanism 105 may also generate plasma of a rare gas in the chamber 101 to provide energy to the substrate W and excite the surface of the substrate W.

[0040] As described above, the film forming method according to the embodiment selectively forms a film. The film forming method includes a cooling step (S11) and a film forming step (S12). In the cooling step, the substrate W with the metal film and the insulating film exposed on the surface and supported in the chamber is cooled to a temperature at which the molecules of c-C4F8 gas and SF6 gas condense on the surface of the substrate W. In the film forming step, a process gas containing c-C4F8 gas and SF6 gas is supplied into the chamber 101 and the surface of the substrate W is excited to form a carbon-containing film on the metal film. In this way, the film forming method according to the embodiment can selectively form a film on the metal film of the substrate W with the metal film and the insulating film exposed on the surface without providing a mask.

[0041] In the cooling step, the substrate W is cooled to 120[K] or less. This allows the film forming method according to the embodiment to condense the molecules of the c-C4F8 gas and the SF6 gas on the surface of the substrate W.

[0042] The metal film is a Cu film, and the insulating film is a SiO2 film. As a result, the film forming method according to the embodiment can selectively form a film on the Cu film of the substrate W without providing a mask.

[0043] In addition, in the film formation process, a process gas containing c-C4F8 gas and SF6 gas in a ratio of 1:3 to 3:1 is supplied into the chamber 101. As a result, the film formation method according to the embodiment can selectively form a film on the metal film of the substrate W in which the metal film and the insulating film are exposed on the surface without providing a mask.

[0044] Moreover, the film forming method according to the embodiment further includes an insulating film forming step. In the insulating film forming step, after forming the carbon-containing film, a source gas of the insulating film is supplied into the chamber 101, and a second insulating film is formed on the insulating film using the carbon-containing film as a mask. In this way, the film forming method according to the embodiment can selectively form the second insulating film on the insulating film.

[0045] Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative and not restrictive in all respects. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the claims.

[0046] For example, in the above embodiment, the substrate W is a semiconductor wafer, but the present invention is not limited to this. The substrate W may be any type.

[0047] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0048] 100 Film deposition equipment 101 Chamber 102 Stages 103 Gas supply mechanism 104 Exhaust system 105 Excitation Mechanism 112 Gate valve 113 Molecular Turbo Pump 114 Auxiliary exhaust pump 150 Control section 151 User Interface 152 Storage section 200 Cu film 201 SiO2 film W substrate

Claims

1. A method for selectively forming a film, comprising the steps of: The substrate with the metal film and the insulating film exposed on the surface and supported in the chamber is subjected to c-C ４ F ８ Gas and SF ６ a cooling step of cooling the substrate to a temperature at which gas molecules condense on the surface of the substrate; c-C ４ F ８ Gas and SF ６ a film formation step of supplying a process gas containing a gas into the chamber and exciting the surface of the substrate to form a carbon-containing film on the metal film; The film forming method includes the steps of:

2. The cooling step is to cool the substrate to 120 K or less. The film forming method according to claim 1 .

3. the metal film is a Cu film, The insulating film is made of SiO ２ It is a membrane The film forming method according to claim 1 or 2.

4. The film forming process is a c-C ４ F ８ Gas and SF ６ A process gas containing gases in a ratio of 1:3 to 3:1 is supplied into the chamber. The film forming method according to any one of claims 1 to 3.

5. an insulating film forming step of supplying a source gas of an insulating film into the chamber after forming the carbon-containing film, and forming a second insulating film on the insulating film using the carbon-containing film as a mask; The film forming method according to any one of claims 1 to 3, further comprising:

6. a chamber having a stage therein for supporting a substrate having a metal film and an insulating film exposed on a surface thereof; The substrate supported by the stage is subjected to a c-C ４ F ８ Gas and SF ６ a cooling unit that cools the gas to a temperature at which gas molecules condense on the surface of the substrate; c-C ４ F ８ Gas and SF ６ a supply unit that supplies a process gas containing a gas into the chamber; an excitation mechanism for exciting a surface of the substrate; a control unit that controls the supply of the processing gas from the supply unit into the chamber while exciting the surface of the substrate by the excitation mechanism to form a carbon-containing film on the metal film; A film forming apparatus having the above structure.

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