Detection Method

Abstract

To detect a status of a film during film deposition.SOLUTION: A detection method for detecting a status of a film during film deposition, includes the steps of: preparing a substrate in a chamber; depositing a film on the substrate by repeating a plurality of steps including an adsorption step of depositing a film on the substrate by ALD (Atomic Layer Deposition), wherein the ALD supplies a raw material gas into the chamber to be adsorbed to the substrate, and a reaction step of supplying a reaction gas into the chamber and making it react with the raw material gas to form a film on the substrate, and acquiring measurement data by irradiating the substrate with infrared light in each step; and extracting a difference in the measurement data between before and after each step.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to detection methods. [Background technology]

[0002] Patent Document 1 discloses a technology in which a film is formed on a film-forming substrate and a monitor substrate, the thin film formed on the monitor substrate is analyzed by infrared spectroscopy, and the quality of the film formed on the film-forming substrate is optimized based on the analytical values. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-56010 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for detecting the state of a film during deposition. [Means for solving the problem]

[0005] A detection method according to one aspect of the present disclosure is a detection method for detecting the state of a film during film formation, the detection method including a step of preparing a substrate in a chamber and a step of forming a film on the substrate by ALD (Atomic Layer Deposition), in which a film is formed on the substrate by repeating a plurality of steps including an adsorption step of supplying a source gas into the chamber and causing it to be adsorbed onto the substrate, and a reaction step of supplying a reactant gas into the chamber and causing it to react with the source gas to form a film on the substrate, and in each step, a step of acquiring measurement data by irradiating the substrate with infrared light, and a step of extracting the difference in the measurement data before and after each step. [Effects of the Invention]

[0006] According to the present disclosure, the state of a film can be detected during film formation. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a film forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating film formation using plasma according to an embodiment. [Figure 3A] FIG. 3A is a diagram illustrating the analysis by TEM-EDX. [Figure 3B] FIG. 3B is a diagram illustrating the analysis by TEM-EDX. [Figure 4] FIG. 4 is a diagram illustrating a conventional FT-IR analysis. [Figure 5] FIG. 5 is a diagram illustrating the flow of the film forming method according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating difference data according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of a plasma ALD process according to the embodiment. [Figure 8A] FIG. 8A is a diagram showing an example of a substrate on which a SiN film according to an embodiment is formed. [Figure 8B] FIG. 8B is a diagram showing an example of a silicon substrate on which a SiN film is formed according to a comparative example. [Figure 9] FIG. 9 is a diagram showing an example of absorbance for each wave number of infrared light. [Figure 10A] FIG. 10A is a diagram showing an example of absorbance for each wave number of infrared light. [Figure 10B] FIG. 10B is a diagram showing an example of absorbance for each wave number of infrared light. [Figure 10C] FIG. 10C is a diagram showing an example of absorbance for each wave number of infrared light. [Figure 11] FIG. 11 is a schematic configuration diagram showing another example of the film forming apparatus according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the detection method disclosed in the present application will be described in detail with reference to the drawings. However, the disclosed detection method is not limited to the embodiments.

[0009] In the manufacture of semiconductor devices, a film is formed on a substrate such as a semiconductor wafer on which a pattern including recesses is formed using a film formation apparatus. The film formation apparatus places the substrate in a chamber (processing vessel) that is maintained at a predetermined vacuum level, supplies a film formation source gas into the chamber, and generates plasma to form a film on the substrate. Known film formation techniques include plasma CVD (Chemical Vapor Deposition) and plasma ALD (Atomic Layer Deposition).

[0010] As patterns formed on substrates become increasingly finer, plasma deposition tends to result in poor film quality on the sidewalls and bottoms of recesses in the pattern. Therefore, we deposit films on flat monitor substrates, separate from the actual substrates on which semiconductor devices are manufactured, and analyze the films formed on the monitor substrates using infrared spectroscopy to infer the state of films formed on actual substrates.

[0011] However, the state of the film formed on the actual substrate differs from that on the monitor substrate, and even if the film formed on the monitor substrate is analyzed by infrared spectroscopy, the state of the film formed on the actual substrate cannot be determined.

[0012] Therefore, a technology for detecting the state of a film formed on a substrate on which a pattern including recesses is formed is desired.

[0013] [Embodiment] [Configuration of film deposition equipment] Next, an embodiment will be described. First, a film formation apparatus 100 according to the embodiment will be described. FIG. 1 is a schematic cross-sectional view showing an example of the schematic configuration of the film formation apparatus 100 according to the embodiment. In one embodiment, the film formation apparatus 100 is an apparatus that forms a film on a substrate W. The film formation apparatus 100 shown in FIG. 1 has an airtight chamber 1 that is electrically grounded. The chamber 1 is cylindrical and made of, for example, aluminum, nickel, or the like, with an anodized coating formed on the surface. A mounting table 2 is provided within the chamber 1.

[0014] The mounting table 2 is made of a metal such as aluminum or nickel. A substrate W such as a semiconductor wafer is placed on the upper surface of the mounting table 2. The mounting table 2 supports the placed substrate W horizontally. The lower surface of the mounting table 2 is electrically connected to a support member 4 made of a conductive material. The mounting table 2 is supported by the support member 4. The support member 4 is supported by the bottom surface of the chamber 1. The lower end of the support member 4 is electrically connected to the bottom surface of the chamber 1 and is grounded via the chamber 1. The lower end of the support member 4 may be electrically connected to the bottom surface of the chamber 1 via a circuit adjusted to reduce the impedance between the mounting table 2 and the ground potential.

[0015] The mounting table 2 has a built-in heater 5, and the heater 5 can heat the substrate W mounted on the mounting table 2 to a predetermined temperature. The mounting table 2 may have a channel (not shown) formed therein for circulating a coolant, and the coolant, whose temperature is controlled by a chiller unit provided outside the chamber 1, may be circulated through the channel. The mounting table 2 may control the substrate W to a predetermined temperature by heating with the heater 5 and cooling with the coolant supplied from the chiller unit. Alternatively, the heater 5 may not be installed, and the temperature of the mounting table 2 may be controlled only by the coolant supplied from the chiller unit.

[0016] An electrode may be embedded in the mounting table 2. A DC voltage is supplied to this electrode, which generates an electrostatic force that causes the mounting table 2 to attract the substrate W placed on its upper surface. The mounting table 2 is also provided with lifting pins (not shown) for transferring the substrate W to and from a transfer mechanism (not shown) provided outside the chamber 1.

[0017] A substantially disk-shaped showerhead 16 is provided above the mounting table 2 on the inner surface of the chamber 1. The showerhead 16 is supported on the upper part of the mounting table 2 via an insulating member 45 such as ceramic, thereby electrically insulating the chamber 1 from the showerhead 16. The showerhead 16 is made of a conductive metal such as nickel.

[0018] The shower head 16 has a top plate member 16a and a shower plate 16b. The top plate member 16a is provided to close the interior of the chamber 1 from above. The shower plate 16b is provided below the top plate member 16a to face the mounting table 2. A gas diffusion space 16c is formed in the top plate member 16a. A large number of gas discharge holes 16d that open toward the gas diffusion space 16c are formed and dispersed in the top plate member 16a and the shower plate 16b.

[0019] The top plate member 16a is formed with a gas inlet 16e for introducing various gases into the gas diffusion space 16c. The gas inlet 16e is connected to a gas supply path 15a. The gas supply path 15a is connected to the gas supply unit 15.

[0020] The gas supply unit 15 has gas supply lines connected to gas supply sources of various gases used in film formation. Each gas supply line branches appropriately according to the film formation process and is provided with control devices for controlling the flow rate of the gas, such as valves such as on-off valves and flow rate controllers such as mass flow controllers. The gas supply unit 15 can control the flow rate of various gases by controlling the control devices, such as on-off valves and flow rate controllers, provided on each gas supply line.

[0021] The gas supply unit 15 supplies various gases used in film formation to the gas supply path 15a. For example, the gas supply unit 15 supplies a source gas for film formation to the gas supply path 15a. The gas supply unit 15 also supplies a purge gas and a reactive gas that reacts with the source gas to the gas supply path 15a. The gas supplied to the gas supply path 15a is diffused in the gas diffusion space 16c and discharged from each gas discharge hole 16d.

[0022] The space surrounded by the lower surface of the shower plate 16b and the upper surface of the mounting table 2 forms a processing space where a film formation process is performed. The shower plate 16b is paired with the mounting table 2, which is grounded via the support member 4 and the chamber 1, and is configured as an electrode plate for forming a capacitively coupled plasma (CCP) in the processing space. A high-frequency power source 10 is connected to the shower head 16 via a matching box 11, and the CCP is formed by supplying high-frequency power (RF power) to a gas supplied from the high-frequency power source 10 to the processing space 40 via the shower head 16. Note that the high-frequency power source 10 may be connected to the mounting table 2 instead of the shower head 16, and the shower head 16 may be grounded. In this embodiment, the parts that perform film formation, such as the shower head 16, the gas supply unit 15, and the high-frequency power source 10, correspond to the film formation unit of the present disclosure.

[0023] An exhaust port 71 is formed at the bottom of the chamber 1, and an exhaust device 73 is connected to this exhaust port 71 via an exhaust pipe 72. The exhaust device 73 has a vacuum pump and a pressure adjustment valve, and by operating this vacuum pump and pressure adjustment valve, the pressure inside the chamber 1 can be reduced and adjusted to a predetermined vacuum level.

[0024] Windows 80a and 80b are provided on the side wall of the chamber 1 at positions facing each other across the mounting table 2. The windows 80a and 80b are fitted with and sealed by a member transparent to infrared light, such as quartz. An irradiation unit 81 that irradiates infrared light is provided outside the window 80a. A detection unit 82 that can detect infrared light is provided outside the window 80b. The positions of the window 80a and the irradiation unit 81 are adjusted so that the infrared light irradiated from the irradiation unit 81 is irradiated onto the substrate W through the window 80a. The positions of the window 80b and the detection unit 82 are adjusted so that the infrared light reflected by the substrate W is incident on the detection unit 82 through the window 80b. A loading / unloading port (not shown) for loading and unloading the substrate W is provided on the side wall of the chamber 1 different from the windows 80a and 80b. A gate valve that opens and closes the loading / unloading port is provided at the loading / unloading port.

[0025] The irradiation unit 81 is disposed so that the irradiated infrared light strikes a predetermined region near the center of the substrate W through the window 80a. For example, the irradiation unit 81 irradiates an area of ​​the substrate W within a range of about 1 to 10 mm with the infrared light. The detection unit 82 is disposed so that the infrared light reflected from the predetermined region of the substrate W enters through the window 80b.

[0026] The film formation apparatus 100 according to this embodiment uses infrared spectroscopy (IR) to determine the absorbance for each wave number of infrared light reflected by the substrate W, thereby detecting the state of the film formed on the substrate W. Specifically, the film formation apparatus 100 uses Fourier transform infrared spectroscopy (FT-IR) to determine the absorbance for each wave number of the reflected infrared light, thereby detecting substances contained in the film formed on the substrate W.

[0027] The irradiation unit 81 incorporates a light source that emits infrared light, and optical elements such as mirrors and lenses, and is capable of irradiating interfered infrared light. For example, the irradiation unit 81 splits the intermediate portion of the optical path of infrared light generated by the light source until it is emitted to the outside into two optical paths using a half mirror or the like, and varies the optical path length of one relative to the optical path length of the other to change the optical path difference and cause interference, thereby irradiating infrared light of various interference waves with different optical path differences. Note that the irradiation unit 81 may be provided with a plurality of light sources, and the infrared light of each light source may be controlled by optical elements to be capable of irradiating infrared light of various interference waves with different optical path differences.

[0028] The detection unit 82 detects the signal intensity of the infrared light of various interference waves reflected by the substrate W. In this embodiment, the parts that perform infrared spectroscopy measurement, such as the irradiation unit 81 and the detection unit 82, correspond to the measurement unit of the present disclosure.

[0029] The operation of the film forming apparatus 100 configured as above is controlled comprehensively by a control unit 60. To the control unit 60, a user interface 61 and a storage unit 62 are connected.

[0030] The user interface 61 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 61 accepts various operations. For example, the user interface 61 accepts a predetermined operation to instruct the start of plasma processing.

[0031] The storage unit 62 stores programs (software) for realizing various processes executed in the film forming apparatus 100 under the control of the control unit 60, as well as data such as processing conditions and process parameters. 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 as needed from another device, for example, via a dedicated line, and used online.

[0032] The control unit 60 is, for example, a computer including a processor, a memory, etc. The control unit 60 reads out programs and data from the storage unit 62 based on instructions from the user interface 61, etc., and controls each unit of the film forming apparatus 100 to execute the processes of the film forming method described below.

[0033] The control unit 60 is connected to the irradiation unit 81 and the detection unit 82 via an interface (not shown) that inputs and outputs data, and inputs and outputs various types of information. The control unit 60 controls the irradiation unit 81 and the detection unit 82. For example, the irradiation unit 81 irradiates various interference waves with different optical path differences based on control information from the control unit 60. In addition, the control unit 60 receives information on the signal intensity of infrared light detected by the detection unit 82.

[0034] Semiconductor devices are becoming increasingly miniaturized, and patterns formed on substrates W have increasingly complex nanoscale shapes. When forming films using plasma, the quality of the film on the sidewalls and bottoms of recesses included in the nanoscale fine patterns tends to deteriorate. FIG. 2 is a diagram illustrating film formation using plasma according to an embodiment. FIG. 2 shows a substrate W. A pattern 90 including nanoscale recesses 90a is formed on the substrate W. When forming films using plasma, ions and radicals have difficulty reaching the sidewalls and bottoms of the recesses 90a, and the quality of the film on the sidewalls and bottoms of the recesses 90a tends to deteriorate. To improve the film quality, it is necessary to analyze the composition of the film on the sidewalls and bottoms of the recesses 90a.

[0035] Techniques for analyzing the deposited film include, for example, energy dispersive X-ray spectroscopy such as TEM-EDX, and infrared spectroscopy such as Fourier transform infrared spectroscopy (FT-IR).

[0036] 3A and 3B are diagrams illustrating analysis by TEM-EDX. FIG. 3A schematically shows a state in which a SiN film 91 is formed by plasma ALD on a pattern 90 having recesses 90a. The SiN film 91 on the bottom 90b of the recesses 90a, the sidewalls 90c, and the top surface 90d of the pattern 90 were analyzed by TEM-EDX. FIG. 3B shows an example of the results of TEM-EDX analysis of the SiN film 91 on the bottom 90b, the sidewalls 90c, and the top surface 90d. TEM-EDX allows the elemental composition of the SiN film 91 to be determined.

[0037] FIG. 3B shows the percentages of N (nitrogen), O (oxygen), and Si (silicon) at the bottom 90b, sidewall 90c, and top surface 90d. The percentage of N is higher at the top surface 90d than at the bottom 90b and sidewall 90c. The percentage of O increases in the order of the top surface 90d, sidewall 90c, and bottom 90b. The percentage of Si is lower at the top surface 90d than at the bottom 90b and sidewall 90c. These results indicate differences in elemental composition among the bottom 90b, sidewall 90c, and top surface 90d, necessitating more detailed analysis. However, while TEM-EDX can detect elements, it cannot detect chemical bonds. For example, it is unclear whether N is bonded to O or Si. TEM-EDX analysis cannot detect light atoms such as H (hydrogen).

[0038] FIG. 4 illustrates a conventional FT-IR analysis. Conventionally, FT-IR analysis involves depositing a film on a flat monitor substrate (separate from the actual substrate W used for manufacturing semiconductor devices), irradiating the monitor substrate with infrared light, and analyzing the light transmitted through or reflected by the monitor substrate to infer the state of the film deposited on the actual substrate W. FIG. 4 schematically illustrates a SiN film 96 deposited on a flat monitor silicon substrate 95 by plasma ALD. In FIG. 4, infrared light is irradiated onto the silicon substrate 95, and the light transmitted through the silicon substrate 95 is detected by a detector for FT-IR analysis. FT-IR analysis can obtain information about chemical bonds. FT-IR analysis can also observe the vibration of hydrogen atoms, allowing the detection of light atoms such as hydrogen. For example, in a SiN film 96, the molecules vibrate upon absorption of infrared light, allowing the detection of chemical bonds such as SiN, SiO, SiH, and NH.

[0039] However, the state of the film formed on the actual substrate W used to manufacture the semiconductor device differs from that of the silicon substrate 95 used for monitoring, and even if the SiN film 96 formed on the silicon substrate 95 is analyzed by infrared spectroscopy, the state of the SiN film 91 formed on the substrate W cannot be determined.

[0040] Therefore, in the film forming apparatus 100 according to the embodiment, the control unit 60 controls each unit to perform the following process of the film forming method, and the composition of the film formed on the substrate W is analyzed.

[0041] 5 is a diagram illustrating the flow of a film formation method according to an embodiment. First, a substrate on which a pattern including recesses is formed before film formation is measured by infrared spectroscopy (step S10). For example, a substrate W on which a film is to be formed and on which a pattern 90 including recesses 90a is formed on its surface is placed on a mounting table 2. In the film formation apparatus 100, a control unit 60 controls an irradiation unit 81 to irradiate the substrate W with infrared light from the irradiation unit 81 before film formation, and a detection unit 82 detects the infrared light reflected by the substrate W, and the control unit 60 performs FT-IR analysis.

[0042] Next, a film is formed on the substrate using plasma such as plasma CVD or plasma ALD (step S11). For example, the control unit 60 controls the gas supply unit 15 and the high-frequency power supply 10 to form a SiN film 91 on the surface of the substrate W by plasma ALD.

[0043] Next, the substrate after film formation is measured by infrared spectroscopy (step S12). For example, in the film formation apparatus 100, the control unit 60 controls the irradiation unit 81, and after film formation, the irradiation unit 81 irradiates the substrate W with infrared light, and the detection unit 82 detects the infrared light reflected by the substrate W, and the control unit 60 performs FT-IR analysis.

[0044] Next, differential data between the measurement data measured in step S10 and the measurement data measured in step S12 is extracted (step S13). For example, the control unit 60 extracts differential data between the measurement data before film formation and the measurement data after film formation. FIG. 6 is a diagram illustrating differential data according to an embodiment. In FIG. 6, a substrate W on which a pattern 90 including recesses 90a is formed is shown as "before film formation." Furthermore, a substrate W on which a SiN film 91 is formed on the pattern 90 is shown as "after film formation." By extracting the difference between the measurement data before film formation and the measurement data after film formation, a signal of the SiN film 91 can be extracted as differential data.

[0045] Next, based on the extracted difference data, the state of the film formed on the substrate W is displayed (step S14). For example, the control unit 60 detects chemical bonds contained in the SiN film 91 based on the difference data, and displays the detected chemical bonds on the user interface 61.

[0046] Furthermore, the control unit 60 controls the process parameters for film formation based on the extracted difference data (step S15). For example, the control unit 60 detects chemical bonds contained in the SiN film 91 based on the difference data, and controls the process parameters in accordance with the detected chemical bonds.

[0047] An example of a specific detection result will now be described. A SiN film 91 was formed on a substrate W on which a pattern 90 including recesses 90a was formed by plasma ALD using a film formation method according to an embodiment. FIG. 7 illustrates an example of a plasma ALD process according to an embodiment. In plasma ALD, first, DCS (DiChloroSilane: SiH2Cl2) gas is supplied to adsorb a precursor onto the substrate W, and then the DCS gas is purged. Next, while supplying H2 gas, high-frequency power of 13 MHz is supplied to generate plasma for modification. Next, while supplying NH3 gas, high-frequency power of 13 MHz is supplied to generate plasma for nitridation. By repeating these steps using plasma ALD, a SiN film of the desired thickness was formed.

[0048] 8A is a diagram showing an example of a substrate W on which a SiN film 91 according to an embodiment is formed. The substrate W has a pattern 90 including recesses 90a formed in single crystal silicon (c-Si). The pattern 90 has an aspect ratio of 8 between the depth and diameter of the recesses 90a. The SiN film 91 is formed on the pattern 90 of the substrate W.

[0049] The control unit 60 extracted differential data between the FT-IR analysis measurement data before and after film formation from the FT-IR analysis measurement data after film formation. For example, the control unit 60 calculates the infrared light absorbance for each wavenumber of infrared light from the measurement data before and after film formation. Then, the control unit 60 subtracts the infrared light absorbance before film formation from the infrared light absorbance after film formation for each wavenumber to extract the infrared light absorbance by the SiN film 91 for each wavenumber as differential data.

[0050] As a comparative example, a SiN film was formed on a flat silicon substrate by plasma ALD using the film formation method according to the embodiment. FIG. 8B illustrates an example of a silicon substrate 95 on which a SiN film 96 according to the comparative example was formed. The silicon substrate 95 is a silicon wafer with a flat upper surface, and a SiN film 96 was formed on the upper surface. Similarly, for the comparative example, the control unit 60 extracted differential data between the FT-IR analysis data obtained before film formation and the FT-IR analysis data obtained after film formation. For example, the control unit 60 calculated the infrared absorbance for each wavenumber of infrared light from the measurement data obtained before and after film formation. The control unit 60 then subtracted the infrared absorbance before film formation from the infrared absorbance after film formation for each wavenumber to extract the infrared absorbance by the SiN film 96 for each wavenumber as differential data.

[0051] FIG. 9 is a diagram showing an example of absorbance at each wavenumber of infrared light. The horizontal axis of FIG. 9 represents the wavenumber of infrared light. The vertical axis represents the absorbance of infrared light. FIG. 9 also shows a waveform L1 representing the absorbance at each wavenumber of a SiN film 91 formed on a pattern 90 on a substrate W. As a comparative example, FIG. 9 also shows a waveform L2 representing the absorbance at each wavenumber of a SiN film 96 formed on a flat silicon substrate 95. The shorter the wavelength of infrared light, the greater the wavenumber. The wavenumber of absorbed infrared light varies depending on the substance. Therefore, FT-IR analysis can identify the substance contained in the sample from the wavenumber of infrared light. FT-IR analysis can also estimate the content of the substance from the absorbance at each wavenumber. FT-IR analysis can also estimate the thickness (film thickness) of the deposited film from the absorbance at each wavenumber.

[0052] 8A and 8B, the SiN film 91 is formed on the sidewalls and bottom of the recesses 90a of the pattern 90, and therefore has a larger volume than the SiN film 96 on the flat silicon substrate 95. For this reason, the waveform L1 of the SiN film 91 has a higher absorbance than the waveform L2 of the SiN film 96. The waveform L1 can detect weaker signals than the waveform L2, and therefore can detect even trace amounts of substances.

[0053] In the SiN film 91, the higher the aspect ratio of the recesses 90a of the pattern 90, the larger the volume of SiN on the sidewalls of the recesses 90a. Therefore, the higher the aspect ratio of the recesses 90a, the more dominant the component of the sidewalls of the recesses 90a becomes in the waveform L1. In other words, the higher the aspect ratio of the recesses 90a, the more the waveform L1 represents the state of the sidewalls of the recesses 90a.

[0054] 10A to 10C are diagrams showing an example of absorbance at each wavenumber of infrared light. The horizontal axis of each of FIGS. 10A to 10C represents the wavenumber of infrared light. The vertical axis represents the absorbance of infrared light normalized by the area of ​​the SiN film. Each of FIGS. 10A to 10C shows a waveform L1 representing the absorbance at each wavenumber of a SiN film 91 formed on a pattern 90 of a substrate W, and a waveform L2 representing the absorbance at each wavenumber of a SiN film 96 formed on a flat silicon substrate 95 as a comparative example. Each of FIGS. 10A to 10C also shows the wavenumber position of infrared light absorbed by each compound and chemical bond. As shown by the waveforms L1 and L2, the SiN film 91 formed on the pattern 90 and the SiN film 96 formed on the silicon substrate 95 exhibit different states. For example, as shown in FIG. 10A, the absorbance at the Si-N position in waveform L2 is greater than that in waveform L1. On the other hand, waveform L1 has greater absorbance at the positions of Si-N, Si-O, and NH than waveform L2. Therefore, the SiN film 91 formed on pattern 90 contains Si-O and NH in addition to Si-N. Also, as shown in FIG. 10B, waveform L2 has smaller absorbance at the position of NH. On the other hand, waveform L2 has larger absorbance at the position of NH. Therefore, the SiN film 91 formed on pattern 90 also contains NH. Also, as shown in FIG. 10C, waveform L1 has greater absorbance at the position of NH than waveform L2. Therefore, the SiN film 91 formed on pattern 90 contains a large amount of NH. Thus, the states of the SiN film 91 and the SiN film 96 formed on the substrate W on which pattern 90 is formed and the flat silicon substrate 95 are different. For example, in the cases of FIGS. 10A to 10C, the SiN film 91 contains a large amount of NH, SiO, and NH. This causes a deterioration in the WER (Wet Etching Rate). The reason why NH, SiO, and NH2 are present in the SiN film 91 is that ions and radicals do not sufficiently reach the sidewalls of the recesses 90a, resulting in insufficient nitriding. In this way, the state of the SiN film 91, such as the substances and chemical bonds contained in the SiN film 91, can be determined from the differential data. For example, NH x , SiH x , SiO, and other substances that affect the film quality of the SiN film 91 can be detected.

[0055] The control unit 60 displays the state of the SiN film 91 formed on the substrate W based on the difference data. For example, the control unit 60 displays a waveform L1 indicating the absorbance of the SiN film 91 at each wavenumber on the user interface 61, as shown in FIG. 9 and FIGS. 10A to 10C. Furthermore, for example, the control unit 60 identifies substances and chemical bonds contained in the SiN film 91 from the absorbance at the position of the wavenumber of infrared light absorbed by each substance or chemical bond, and displays the identified substances and chemical bonds on the user interface 61. The control unit 60 may also estimate the film thickness of the formed SiN film 91 from the absorbance at each wavenumber and display the estimated film thickness on the user interface 61.

[0056] Furthermore, the control unit 60 detects chemical bonds contained in the SiN film 91 based on the difference data and controls process parameters according to the detected chemical bonds. For example, when the SiN film 91 is insufficiently nitrided as shown in FIGS. 10A to 10C, the control unit 60 controls the film formation process parameters to promote nitridation. For example, the control unit 60 controls the process parameters to increase the flow rate of NH3 gas supplied for nitridation and to lengthen the nitridation time. This allows the film formation apparatus 100 to promote nitridation in subsequent film formation, thereby improving the film quality of the SiN film 91 formed on the pattern 90.

[0057] Although the present embodiment has been described with reference to an example in which FT-IR analysis is performed before and after the formation of the SiN film 91, this is not limiting. FT-IR analysis may be performed before and after a specific plasma ALD process to obtain measurement data and extract differential data for the specific process. For example, FT-IR analysis may be performed before and after the precursor adsorption process, modification process, and nitridation process of the plasma ALD shown in FIG. 7 to obtain measurement data and extract differential data. Alternatively, FT-IR analysis may be performed continuously during each process, and the difference between the data before each process and the real-time data may be monitored in real time. This allows the status of the adsorption process, modification process, and nitridation process to be detected in real time from the differential data for the adsorption process, modification process, and nitridation process. For example, the degree of precursor adsorption in the adsorption process can be detected, and whether a desired amount of precursor is adsorbed can be detected in real time. Furthermore, the degree of modification in the modification process can be detected, and whether the desired modification is being performed can be detected in real time. Furthermore, the degree of nitridation can be detected in the nitridation process, enabling real-time detection of whether the desired plasma nitridation is being performed. The control unit 60 controls process parameters based on the differential data. For example, if the control unit 60 detects the state of adsorption, modification, or nitridation in the adsorption, modification, or nitridation process from the differential data and determines that adsorption, modification, or nitridation is insufficient, it controls the process parameters to perform the insufficient process. This prevents insufficient adsorption, modification, or nitridation and improves the film quality of the SiN film 91 formed. Furthermore, if an unnecessarily long process time is required, the process time can be shortened, thereby increasing productivity. Furthermore, for example, FT-IR analysis may be performed before or after each plasma ALD process shown in FIG. 7 to obtain measurement data, and differential data for each process may be extracted from the measurement data of the previous process. This allows the state of each process to be detected in real time from the differential data for each process.

[0058] As described above, the film formation method according to the embodiment includes a first measurement step (step S10), a film formation step (step S11), a second measurement step (step S12), and an extraction step (step S13). In the first measurement step, the substrate W on which the pattern 90 including the recesses 90a is formed is measured by infrared spectroscopy. In the film formation step, a film is formed on the substrate W after the first measurement step. This film formation step may include a modification step. Alternatively, the film formation step may be a modification step. In the second measurement step, the substrate W is measured by infrared spectroscopy after the film formation step. In the extraction step, difference data between the measurement data of the first measurement step and the measurement data of the second measurement step is extracted. As a result, the film formation method according to the embodiment can detect the state of the film formed on the substrate W on which the pattern 90 including the recesses 90a is formed.

[0059] Furthermore, the extraction step determines the absorbance of infrared light for each wavenumber of infrared light from the measurement data before film formation in the first measurement step and the measurement data after film formation in the second measurement step. The extraction step extracts the absorbance of infrared light by the film for each wavenumber as difference data by subtracting the absorbance of infrared light before film formation from the absorbance of infrared light after film formation for each wavenumber. This allows the film formation method according to the embodiment to detect the state of the film formed on the substrate W from the absorbance of infrared light for each wavenumber extracted as difference data.

[0060] Furthermore, the film formation method according to the embodiment includes a display step (step S14) of displaying the state of the film formed on the substrate W in the film formation step based on the difference data extracted in the extraction step. This allows the film formation method according to the embodiment to present the state of the film actually formed on the substrate W to the process manager.

[0061] Furthermore, the film formation method according to the embodiment includes a control step (step S15) of controlling process parameters of the film formation step based on the difference data extracted in the extraction step. This allows the film formation method according to the embodiment to adjust the process parameters depending on the state of the film actually formed on the substrate W, thereby improving the film quality of the film formed on the substrate W in subsequent film formation.

[0062] Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative in all respects and not restrictive. 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.

[0063] For example, in the above embodiment, infrared light is reflected near the center of the substrate W to detect the film state near the center of the substrate W. However, this is not limiting. For example, optical elements such as mirrors and lenses that reflect infrared light may be provided in the chamber 1, and the optical elements may irradiate multiple locations on the substrate W, such as near the center and near the periphery, with the infrared light. The infrared light reflected from each location may be detected to detect the film state at each of the multiple locations on the substrate W. For example, FT-IR analysis may be performed at multiple locations on the substrate W before and after film formation to obtain measurement data. The control unit 60 extracts difference data between the measurement data after film formation and the measurement data before film formation for each of the multiple locations. The control unit 60 controls process parameters based on the extracted difference data for the multiple locations. For example, if the SiN film 91 is insufficiently nitrided at any location, the control unit 60 controls the film formation process parameters to promote nitridation. The control unit 60 may estimate film thicknesses at multiple locations on the substrate W based on the difference data for the multiple locations to detect the film thickness distribution. The control unit 60 may control the process parameters so as to achieve a predetermined film quality while uniforming the film thickness distribution. For example, when the film thickness distribution of the SiN film 91 is non-uniform and the SiN film 91 is insufficiently nitrided at some points, the control unit 60 controls the film formation process parameters so as to promote nitridation while uniforming the SiN film 91.

[0064] Furthermore, in the above embodiment, an example has been described in which the process parameters for film formation are controlled based on the difference data for one substrate W, but this is not limiting. The process parameters for the film formation process may also be controlled based on a comparison of the difference data between multiple substrates W. For example, when the film formation apparatus 100 forms films on multiple substrates W, the state of the film formed may change due to changes over time, etc. The control unit 60 changes the process parameters for the film formation process to suppress changes in the state of the film based on the comparison of the difference data between the substrates W. For example, if the SiN film 91 is not sufficiently nitrided, the control unit 60 controls the process parameters for film formation to promote nitridation. This suppresses changes in the state of the film formed on multiple substrates W.

[0065] Although the above embodiment has been described with reference to an example in which the process parameters for film formation are controlled based on the difference data for one substrate W, this is not limiting. The condition of the film formation apparatus 100 changes over time, and the state of the film formed may change even when film formation is performed under the same film formation conditions (recipe). Therefore, the film formation apparatus 100 may periodically form a film under the same film formation conditions, such as every few days or at a predetermined interval, perform FT-IR analysis before and after film formation, and diagnose the condition of the film formation apparatus 100 based on the results of the FT-IR analysis. For example, the film formation apparatus 100 periodically forms a film on a substrate W under the same film formation conditions. The control unit 60 diagnoses the condition of the film formation apparatus 100 based on a comparison of difference data between substrates W from difference data for multiple substrates W formed under the same film formation conditions. This allows the film formation apparatus 100 to detect changes in the condition from changes in the state of films formed under the same film formation conditions.

[0066] In the above embodiment, the film formation apparatus of the present disclosure has been described as a single-chamber type film formation apparatus 100 having one chamber, but the present disclosure is not limited to this. The film formation apparatus of the present disclosure may also be a multi-chamber type film formation apparatus having multiple chambers.

[0067] 11 is a schematic diagram showing another example of a film formation apparatus 200 according to an embodiment. As shown in FIG. 11, the film formation apparatus 200 is a multi-chamber type film formation apparatus having four chambers 201 to 204. In the film formation apparatus 200, plasma ALD is performed in each of the four chambers 201 to 204.

[0068] Chambers 201 to 204 are connected to the four walls of a vacuum transfer chamber 301, which has a heptagonal planar shape, via gate valves G, respectively. The interior of the vacuum transfer chamber 301 is evacuated by a vacuum pump and maintained at a predetermined vacuum level. Three load lock chambers 302 are connected to the other three walls of the vacuum transfer chamber 301 via gate valves G1. An atmospheric transfer chamber 303 is provided on the opposite side of the load lock chamber 302 from the vacuum transfer chamber 301. The three load lock chambers 302 are connected to the atmospheric transfer chamber 303 via gate valves G2. The load lock chambers 302 control the pressure between atmospheric pressure and vacuum when transferring a substrate W between the atmospheric transfer chamber 303 and the vacuum transfer chamber 301.

[0069] Three carrier attachment ports 305 for attaching carriers (FOUPs or the like) C for accommodating substrates W are provided on the wall of the atmospheric transfer chamber 303 opposite to the wall on which the load lock chamber 302 is attached. In addition, an alignment chamber 304 for aligning the substrates W is provided on the side wall of the atmospheric transfer chamber 303. A downflow of clean air is created within the atmospheric transfer chamber 303.

[0070] A transfer mechanism 306 is provided in the vacuum transfer chamber 301. The transfer mechanism 306 transfers the substrate W to and from the chambers 201 to 204 and the load lock chamber 302. The transfer mechanism 306 has two transfer arms 307a and 307b that are independently movable.

[0071] A transfer mechanism 308 is provided in the atmospheric transfer chamber 303. The transfer mechanism 308 transfers the substrate W to the carrier C, the load lock chamber 302, and the alignment chamber 304.

[0072] The film forming apparatus 200 includes a control unit 310. The operation of the film forming apparatus 200 is controlled by the control unit 310.

[0073] In the film formation apparatus 200 configured as described above, a measurement unit for measuring the substrate W by infrared spectroscopy may be provided in a chamber other than the chambers 201 to 204. For example, the film formation apparatus 200 may provide a measurement unit for measuring the substrate W by infrared spectroscopy in the vacuum transfer chamber 301 or one of the load lock chambers 302. For example, the measurement unit may have an irradiation unit for irradiating infrared light and a detection unit for detecting the infrared light arranged vertically. When performing FT-IR analysis, the film formation apparatus 200 places the substrate W in the measurement unit by the transfer mechanism 306. In the measurement unit, the irradiation unit irradiates the substrate W with infrared light, and the detection unit detects the infrared light that has passed through the substrate W.

[0074] The control unit 310 measures the substrate W before film formation using the measurement unit. The control unit 310 forms a film on the substrate W using one of chambers 201 to 204. The control unit 310 measures the substrate W after film formation using the measurement unit. The control unit 310 extracts differential data between the measurement data obtained by the measurement unit before film formation and the measurement data obtained by the measurement unit after film formation. This makes it possible to detect the state of a film formed on the substrate W on which a pattern including recesses is formed, even in the film formation apparatus 200.

[0075] As described above, the technology disclosed herein has been applied to a film formation process to detect the film state, but this is not limiting. The process for detecting the film state is not limited to the film formation process. For example, it may be any process related to a semiconductor manufacturing process for manufacturing semiconductor devices, such as an etching process or a resist process, or multiple processes including a combination of any process. Furthermore, from the perspective of any process and / or multiple processes including a combination of any process related to a semiconductor manufacturing process, the technology disclosed herein may be applied before and after any process or multiple processes to perform intra-process or inter-process diagnosis and monitoring. For example, it may be applied to various triggers (e.g., particles, intra-surface / inter-surface distribution) related to semiconductor manufacturing productivity (e.g., operating rate and yield). Furthermore, as described above, the film formation apparatus disclosed herein has been described using examples of a single-chamber or multi-chamber type film formation apparatus having multiple chambers, but this is not limited thereto. For example, it may be a batch-type film formation apparatus capable of processing multiple substrates at once, or a carousel-type semi-batch type film formation apparatus.

[0076] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered 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]

[0077] W substrate 1 chamber 2 Mounting table 10 High frequency power supply 15 Gas supply section 16 shower head 60 Control Unit 61 User Interface 62 Storage section 80a Window 80b Window 81 Irradiation unit 82 Detector 90 patterns 90a recess 91 SiN film 95 Silicon substrate 96 SiN film 100 Film deposition equipment 200 Film deposition equipment 201~204 Chambers

Claims

1. A detection method for detecting the state of a film during film formation, comprising: providing a substrate in a chamber; a process of depositing a film on the substrate by atomic layer deposition (ALD), the process repeating a plurality of steps including an adsorption step of supplying a source gas into the chamber and causing it to be adsorbed onto the substrate, and a reaction step of supplying a reactive gas into the chamber and causing it to react with the source gas to form a film on the substrate, and in each step, irradiating the substrate with infrared light to acquire measurement data; extracting a difference between the measurement data before and after each step; and In each step of the film forming process, infrared light is irradiated from an irradiation unit provided on one side wall of the chamber, the infrared light irradiated from the irradiation unit is reflected by an optical element that reflects infrared light provided in the chamber and irradiated onto the substrate, and the reflected infrared light is detected by a detection unit provided on the other side wall of the chamber, thereby obtaining the measurement data. Detection method.

2. The ALD includes a modification step, In the extracting step, a difference in measurement data before and after the modifying step is extracted. The detection method according to claim 1 .

3. In the extracting step, the absorbance of infrared light is calculated for each wave number of infrared light from the measurement data before and after each step, and the absorbance of infrared light for each wave number is subtracted to extract the absorbance of infrared light for each wave number as differential data. The detection method according to claim 1 or 2.

4. The method further includes a step of displaying the state of each step based on the differential data extracted by the extracting step. The detection method according to any one of claims 1 to 3.

5. The method further includes a step of controlling parameters for each step based on the difference data extracted in the extracting step. The detection method according to any one of claims 1 to 4.

6. The controlling step determines the film thickness distribution and film quality of the film formed on the substrate from the extracted difference data, and controls the process parameters so as to achieve a predetermined film quality while making the film thickness distribution uniform. The detection method according to claim 5 .

7. The step of forming the film includes periodically forming a film on a substrate under the same film formation conditions; The method further includes a step of diagnosing the condition of an apparatus for performing the film forming step based on a comparison of difference data between substrates from difference data of a plurality of substrates on which films are formed under the same film forming conditions. The detection method according to any one of claims 1 to 6.

8. The source gas is a silicon-containing gas. The detection method according to any one of claims 1 to 7.

9. The reactive gas is a nitrogen-containing gas. The detection method according to any one of claims 1 to 8.

10. The step of modifying the surface of the substrate is carried out by using plasma of hydrogen gas. The detection method according to claim 2 .

11. The infrared light irradiated onto the substrate is an interference wave infrared light having different optical path differences. The detection method according to any one of claims 1 to 10.

12. the substrate is formed with a pattern including a recess; The film is deposited according to a pattern including recesses. The detection method according to any one of claims 1 to 11.

13. The film is a SiN film. The detection method according to any one of claims 1 to 12.

14. The optical elements are provided at a plurality of locations including the center of the substrate and the periphery of the substrate in the chamber. The detection method according to any one of claims 1 to 13.

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