Film thickness measurement system, film thickness measurement method and program

Abstract

To provide a film thickness measuring system, etc. which can measure, with high accuracy, the film thickness of a film on a substrate where a patter is formed.SOLUTION: The film thickness measuring system calculates, for N first substrates having a first film differing in film thickness, the thickness of the first film at a first position using the spectroscopic data of reflected light, acquires the first image data on a surface of a second substrate where a first film is formed, acquires the first color information on a plurality of first subregions in a first region using the first image data with regard to the second substrate, calculates a correlation between the film thickness and color information using the first color information on the second substrate, the first region including a second position corresponding to the first position, the thickness of the first film at the first position being used as the thickness of the second film in the first region for the plurality of first subregions, acquires the second color information on a plurality of second subregions in a second region on a third substrate using the second image data on the third substrate where a third film is formed, and estimates the thickness of the third film in the second region.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a film thickness measurement system, a film thickness measurement method, and a program. [Background technology]

[0002] In Patent Document 1, the thickness of a film formed on a substrate is calculated from an image of the substrate surface. A configuration is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-215193 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a film thickness measurement system, a film thickness measurement method, and a program capable of measuring with high accuracy the film thickness of a film on a substrate on which a pattern is formed. [Means for solving the problem]

[0005] A film thickness measurement system according to one aspect of the present disclosure includes a holding unit configured to hold a substrate, an imaging unit configured to acquire image data of a surface of the substrate held by the holding unit, and a control unit, wherein the control unit receives, for each of N first substrates (N is an integer of 2 or more) having first films with different film thicknesses, spectroscopic data of light reflected at a first position on a surface of the first substrate, and calculates a thickness of each of the first films at the first position using the spectroscopic data, and the imaging unit: First pattern andacquiring first image data of the surfaces of N second substrates on which a second film is formed, acquiring first color information of a plurality of first sub-regions in a first region using the first image data for each of the N second substrates, the first region including a second position corresponding to the first position, using the calculated thickness of each of the first films at the first position for each of the plurality of first sub-regions as the thickness of each of the second films in the first region, and calculating a correlation between film thickness and color information using the first color information of the N second substrates; Second pattern and acquiring second image data of a surface of a third substrate on which a third film is formed, acquiring second color information of a plurality of second sub-regions in a second region on the third substrate using the second image data, the second region corresponding to the first region and the plurality of second sub-regions corresponding to the plurality of first sub-regions, and estimating a thickness of the third film in the second region using the calculated correlation and the second color information of the plurality of second sub-regions. The second substrate is a substrate simulating the third substrate. do. Effect of the Invention

[0006] According to the present disclosure, the thickness of a film on a substrate on which a pattern is formed can be measured with high accuracy. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing an example of a schematic configuration of a substrate processing system. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a film thickness measuring unit. [Diagram 3] FIG. 3 is a block diagram illustrating an example of a functional configuration of the control device. [Figure 4] FIG. 4 is a block diagram illustrating an example of a hardware configuration of the control device. [Diagram 5] FIG. 5 is a flow diagram showing an example of control (acquisition of reference data) by the control device. [Figure 6] FIG. 6 is a flow diagram showing an example of control (estimation of film thickness from spectroscopic spectrum data) by the control device. [Figure 7] FIG. 7 is a flow diagram showing an example of control (acquisition of calibration data) by the control device. [Figure 8] FIG. 8 is a diagram showing an example of a position for acquiring spectral data of a reference wafer. [Figure 9] FIG. 9 is a diagram showing an example of an area for acquiring color information of the calibration wafer. [Figure 10] FIG. 10 is a diagram showing an example of the relationship between the film thickness and the luminance value difference in the first sub-region. [Figure 11] FIG. 11 is a flow diagram showing an example of control (film thickness measurement on product wafers) by the control device. [Figure 12] FIG. 12 is a diagram showing an example of an area for acquiring color information of a product wafer. [Figure 13] FIG. 13 is a diagram showing an example of the measurement results of the film thickness of a film on a bare wafer. [Figure 14] FIG. 14 is a diagram showing the relationship between the film thickness measured using an ellipsometer and the film thickness measured by spectroscopic analysis. [Figure 15] FIG. 15 is a diagram showing an example of the film thickness measurement result. [Figure 16] FIG. 16 is a diagram showing another example of the film thickness measurement result. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description may be omitted.

[0009] [Substrate processing system] First, a substrate processing system will be described. The substrate processing system is a system for forming a film, such as a silicon nitride film, on a substrate. The substrate to be processed is, for example, a semiconductor wafer W. Fig. 1 is a schematic diagram showing an example of a schematic configuration of the substrate processing system.

[0010] The substrate processing system 20 is installed in a clean room, and includes, for example, four process modules PM1, PM2, PM3, and PM4 and two load lock modules LLM around a substantially pentagonal platform or vacuum transfer chamber PH extending in the depth direction of the device. a ,LLM b Although not shown, the substrate processing system 20 includes a system controller for controlling the overall operation of the system.

[0011] More specifically, in the vacuum transfer chamber PH, two process modules PM1 and PM2 are connected to the long side on the left side of the figure via gate valves GV1 and GV2, two process modules PM3 and PM4 are connected to the long side on the right side of the figure via gate valves GV3 and GV4, and a load lock module LLM is connected to a pair of short sides extending downward in a V-shape. a ,LLM b Gate valve GV a ,G.V. b are connected to each other via

[0012] Each of the process modules PM1, PM2, PM3, and PM4 has a vacuum chamber 10 in which the interior is constantly kept at a variable reduced pressure by a dedicated exhaust device (not shown), and is typically configured to place a single wafer W on a mounting table or susceptor (not shown) located in the center of the chamber, and form a desired film using specified power supplies (processing gas, electricity, reduced pressure, etc.).

[0013] Load Lock Module LLM a ,LLM b are door valves DV c ,DV d The load lock chambers 202 are also connected to the atmospheric transfer chamber of the loader transfer chamber LM, which will be described later, via the load lock chambers 202. Each load lock chamber 202 is provided with a mounting table or transfer table (not shown) for temporarily storing the wafer W being transferred between the loader transfer chamber LM and the vacuum transfer chamber PH.

[0014] The vacuum transfer chamber PH is connected to a dedicated vacuum exhaust device (not shown), and the pressure inside the chamber is normally kept at a constant reduced pressure. a ,F b The vacuum transfer robot 204 is provided with a single-wafer type vacuum transfer robot 204 that is capable of sliding, rotating, and ascending / descending operations. The vacuum transfer robot 204 transfers the process modules PM1 to PM4 and the load-lock module LLM in response to commands from a transfer control unit 206. a ,LLM b The wafers W are transported one by one between the above positions.

[0015] Adjacent to the loader transfer chamber LM are a load port LP, an alignment mechanism ORT, and a film thickness measurement unit U3. The load port LP is used to insert and remove a wafer cassette CR capable of storing, for example, 25 wafers W per batch between an external transfer vehicle. Here, the wafer cassette CR is configured as a FOUP (Front open unified pod) or a SMIF (Standard Mechanical Interface) box. The alignment mechanism ORT is used to align the notch or orientation flat of the wafer W to a predetermined position or direction. The film thickness measurement unit U3 measures the film thickness of the film formed on all processed wafers W that have been subjected to film formation in any of the process modules PM1 to PM4 and returned to the loader transfer chamber LM, or on processed wafers W that are periodically sampled.

[0016] The single-wafer atmospheric transfer robot 210 installed in the loader transfer chamber LM is a pair of extendable transfer arms F c ,F d The linear motor 212 is movable in the horizontal direction on the linear guide 214, and is also capable of ascending, descending, and rotating. In response to commands from the transfer control unit 206, the load port LP, the orientation flat alignment mechanism ORT, the load lock module LLM, and the like are connected to the load port LP. a ,LLM b, and the film thickness measurement unit U3 to transport the wafers W one by one.

[0017] Here, a basic wafer transfer sequence for subjecting one wafer in a wafer cassette CR placed in a load port LP to a series of processes in this cluster tool will be described.

[0018] The atmospheric transfer robot 210 in the loader transfer chamber LM takes out one wafer W from the wafer cassette CR on the load port LP while the LP door 216 is open, transfers the wafer W to the alignment mechanism ORT for alignment, and then transfers the wafer W to the load lock module LLM. a ,LLM b Either one of the two (e.g. LLM a ) to the load lock module (LLM) a receives the wafer W under atmospheric pressure, evacuates the chamber after it is carried in, and delivers the semiconductor wafer W under reduced pressure to the vacuum transfer robot 204 in the vacuum transfer chamber PH.

[0019] In the substrate processing system 20, as one system configuration, the same model of film formation apparatus is used for all four process modules PM1 to PM4, and the process modules PM1 to PM4 can perform film formation according to the same recipe.

[0020] The vacuum transfer robot 204 is a transfer arm F a ,F b Using one of the load lock modules (LLM) a The wafer W taken out from the vacuum transfer robot 204 is transferred into one of the process modules PM1 to PM4. In the process module PM1 to PM4 into which the wafer W has been transferred, a film formation process is performed under predetermined process conditions (gas, pressure, power, time, etc.) according to a preset recipe. After the film formation process is completed, the vacuum transfer robot 204 transfers the wafer W out of the process module PM1 to PM4 and transfers it to the load-lock module LLM. a ,LLM b Transport it to one of the two.

[0021] The wafer W that has undergone the deposition process is placed in one of the load-lock modules (e.g., LLM). b When the load lock module (LLM) is loaded, b The interior of the chamber is switched from a reduced pressure state to an atmospheric pressure state. After that, the atmospheric transfer robot 210 in the loader transfer chamber LM transfers the load lock module LLM to the atmospheric pressure state. b The processed wafer W is then taken out from the processing unit U1 and carried into the film thickness measurement unit U3.

[0022] Then, when the film thickness measurement unit U3 finishes measuring or evaluating the film thickness of the wafer W, the atmospheric transfer robot 210 removes the wafer W from the film thickness measurement unit U3 and returns the removed wafer W to the corresponding wafer cassette CR.

[0023] [Film thickness measurement system] Next, a film thickness measurement system according to an embodiment will be described. Fig. 2 is a schematic diagram showing an example of a film thickness measurement system. This film thickness measurement system 1 includes a control device 100 and a film thickness measurement unit U3.

[0024] [Thickness measurement unit] The film thickness measurement unit U3 obtains information related to the surface of a film formed on a substrate to be processed, for example, a semiconductor wafer W, and information related to the film thickness.

[0025] As shown in FIG. 2, the film thickness measurement unit U3 includes a housing 30, a holding unit 31, a driving unit 32, an imaging unit 33, a light projecting / reflecting unit 34, and a spectroscopic measurement unit 40. The holding unit 31 holds the wafer W horizontally. The driving unit 32 uses, for example, an electric motor as a power source and moves the holding unit 31 along a horizontal linear path. The driving unit 32 can also rotate the holding unit 31 in a horizontal plane. The imaging unit 33 has a camera 35 such as a CCD camera. The camera 35 is provided at one end side of the film thickness measurement unit U3 in the moving direction of the holding unit 31 and faces the other end side in the moving direction. The light projecting / reflecting unit 34 projects light into an imaging range and guides reflected light from the imaging range to the camera 35 side. For example, the light projecting / reflecting unit 34 has a half mirror 36 and a light source 37. The half mirror 36 is provided in a position higher than the holder 31, in the middle of the movement range of the driver 32, and reflects light from below towards the camera 35. The light source 37 is provided above the half mirror 36, and irradiates illumination light downward through the half mirror 36.

[0026] The spectroscopic measurement unit 40 has a function of receiving light from the wafer W, dispersing the light, and acquiring a spectrum. The spectroscopic measurement unit 40 has an incident unit 41 that receives the light from the wafer W, a waveguide unit 42 that guides the light received by the incident unit 41, a spectroscope 43 that disperses the light guided by the waveguide unit 42 to acquire a spectrum, and a light source 44. The incident unit 41 is configured to receive light from the center of the wafer W when the wafer W held by the holder 31 moves as the holder 32 moves the wafer W. That is, the incident unit 41 is provided at a position corresponding to the moving path of the center of the holder 31 that moves as the holder 32 moves the wafer W. The incident unit 41 is attached so that the incident unit 41 moves relative to the surface of the wafer W along the radial direction of the wafer W when the holder 31 moves the wafer W. This allows the spectroscopic measurement unit 40 to acquire spectrum at multiple points along the radial direction of the wafer W, including the center of the wafer W. Furthermore, the drive unit 32 rotates the holder 31, so that the spectroscopic measurement unit 40 can obtain the optical spectrum at a plurality of points along the circumferential direction of the wafer W. The waveguide unit 42 is formed of, for example, an optical fiber. The spectrometer 43 separates the incident light and obtains the optical spectrum including the intensity information corresponding to each wavelength. The light source 44 irradiates illumination light downward. As a result, the reflected light from the wafer W enters the spectrometer 43 via the incident unit 41 and the waveguide unit 42.

[0027] The wavelength range of the spectrum acquired by the spectrometer 43 may be, for example, the wavelength range of visible light (380 nm to 780 nm). Therefore, by using a light source that emits visible light as the light source 44 and dispersing the light from the light source 44 reflected on the surface of the wafer W by the spectrometer 43, it is possible to obtain spectrum data in the wavelength range of visible light. The wavelength range of the spectrum acquired by the spectrometer 43 is not limited to the range of visible light, and may be, for example, a wavelength range including infrared light and ultraviolet light. Appropriate spectrometer 43 and light source 44 can be selected depending on the wavelength range of the spectrum data to be acquired.

[0028] The film thickness measurement unit U3 operates as follows to obtain image data of the surface of the wafer W. First, the driving unit 32 moves the holding unit 31. This causes the wafer W to pass under the half mirror 36. During this passage, reflected light from the surface of the wafer W is sequentially sent to the camera 35. The camera 35 forms an image of the reflected light from the surface of the wafer W to obtain image data of the surface of the wafer W. When the thickness of the film formed on the surface of the wafer W changes, the image data of the surface of the wafer W captured by the camera 35 changes, for example, the color of the surface of the wafer W changes according to the film thickness. In other words, obtaining image data of the surface of the wafer W corresponds to obtaining information related to the film thickness of the film formed on the surface of the wafer W. This point will be described later.

[0029] The image data acquired by the camera 35 is sent to the control device 100. The control device 100 can estimate the thickness of the film on the surface of the wafer W based on the image data, and the estimation result is held in the control device 100 as an inspection result.

[0030] Further, in the spectroscopic measurement unit 40, light from the surface of the wafer W is incident and spectroscopic measurement is performed. When the driving unit 32 moves the holding unit 31, the wafer W passes under the incident unit 41. During this passage, reflected light from multiple points on the surface of the wafer W is incident on the incident unit 41, passes through the waveguide unit 42, and is incident on the spectrometer 43. The incident light is dispersed in the spectrometer 43, and spectroscopic spectrum data is obtained. When the thickness of the film formed on the surface of the wafer W changes, the spectroscopic spectrum changes according to the film thickness, for example. In other words, obtaining spectroscopic spectrum data on the surface of the wafer W corresponds to obtaining information related to the film thickness of the film formed on the surface of the wafer W. This point will be described later.

[0031] The spectroscopic data acquired by the spectroscope 43 is sent to the control device 100. The control device 100 can estimate the thickness of the film on the surface of the wafer W based on the spectroscopic data, and the estimation result is held in the control device 100 as an inspection result.

[0032] [Control device] An example of the control device 100 will be described in detail. FIG. 3 is a block diagram showing an example of a functional configuration of the control device. The control device 100 controls each element included in the film thickness measurement unit U3. The control device 100 may be provided independent of the system controller of the substrate processing system 20. The control device 100 may be provided so as to cooperate with or be integrated with the system controller of the substrate processing system 20.

[0033] As shown in FIG. 3, the control device 100 has, as its functional configuration, a film thickness measurement unit 101, a spectral data acquisition unit 102, a reference film thickness acquisition unit 103, a calibration image data acquisition unit 104, a calibration color information acquisition unit 105, a correlation acquisition unit 106, a product image data acquisition unit 107, a product color information acquisition unit 108, a spectral information storage unit 109, and a film thickness estimation unit 110.

[0034] The film thickness measurement unit 101 has a function of controlling operations related to film thickness measurement of product wafers in the film thickness measurement unit U3. During film thickness measurement in the film thickness measurement unit U3, image data and spectroscopic spectrum data are acquired.

[0035] The spectroscopic data acquiring unit 102 has a function of acquiring and storing spectroscopic data relating to the surface of the reference wafer from the spectrometer 43 of the film thickness measuring unit U3. The spectroscopic data stored in the spectroscopic data acquiring unit 102 is used to estimate the film thickness of the film formed on the reference wafer.

[0036] The reference film thickness acquisition unit 103 has a function of calculating the film thickness of the film formed on the reference wafer based on the spectral data held in the spectral data acquisition unit 102. The procedure for calculating the film thickness will be described in detail later. The reference film thickness acquisition unit 103 is an example of a first film thickness acquisition unit.

[0037] The calibration image data acquisition unit 104 has a function of acquiring and storing image data of the surface of the calibration wafer from the imaging unit 33 of the film thickness measurement unit U3. The image data stored in the calibration image data acquisition unit 104 is used to acquire color information of the film formed on the calibration wafer. The calibration image data acquisition unit 104 is an example of a first image data acquisition unit.

[0038] The proofreading color information acquisition unit 105 has a function of acquiring and storing color information included in the image data stored in the proofreading image data acquisition unit 104. The procedure for acquiring color information will be described in detail later. The proofreading color information acquisition unit 105 is an example of a first color information acquisition unit.

[0039] The correlation acquisition unit 106 has a function of acquiring and storing the correlation between the thickness and color information of the film to be measured. The procedure for acquiring the correlation will be described in detail later.

[0040] The product image data acquisition unit 107 has a function of acquiring and storing image data of the surface of the product wafer from the imaging unit 33 of the film thickness measurement unit U3. The image data stored in the product image data acquisition unit 107 is used to acquire color information of the film formed on the product wafer. The product image data acquisition unit 107 is an example of a second image data acquisition unit.

[0041] The product color information acquisition unit 108 has a function of acquiring and storing color information included in the image data stored in the product image data acquisition unit 107. The procedure for acquiring color information will be described in detail later. The product color information acquisition unit 108 is an example of a second color information acquisition unit.

[0042] The spectroscopic information storage unit 109 has a function of storing spectroscopic information used when calculating a film thickness from the spectroscopic data. The spectroscopic data acquired by the film thickness measurement unit U3 varies depending on the type and film thickness of a film formed on the surface of the wafer W. Therefore, the spectroscopic information storage unit 109 stores information related to the correspondence between film thickness and spectroscopic spectrum.

[0043] The film thickness estimation unit 110 estimates the film thickness of the film formed on the product wafer from the color information held in the product color information acquisition unit 108 and the correlation held in the correlation acquisition unit 106. The procedure for estimating the film thickness will be described in detail later. The film thickness estimation unit 110 is an example of an estimation unit.

[0044] The control device 100 is composed of one or more control computers. FIG. 4 is a block diagram showing an example of a hardware configuration of the control device. For example, the control device 100 has a circuit 120 shown in FIG. 4. The circuit 120 has one or more processors 121, a memory 122, a storage 123, and an input / output port 124. The storage 123 has a computer-readable storage medium such as a hard disk. The storage medium stores a program for causing the control device 100 to execute the process procedure described below. The storage medium may be a removable medium such as a non-volatile semiconductor memory, a magnetic disk, or an optical disk. The memory 122 temporarily stores the program loaded from the storage medium of the storage 123 and the calculation result by the processor 121. The processor 121 configures each of the above-mentioned functional modules by executing the above-mentioned programs in cooperation with the memory 122. The input / output port 124 inputs and outputs an electric signal between the control target member and the control target member in accordance with a command from the processor 121.

[0045] The hardware configuration of the control device 100 is not necessarily limited to configuring each functional module by a program. For example, each functional module of the control device 100 may be configured by a dedicated logic circuit or an ASIC (Application Specific Integrated Circuit) that integrates the dedicated logic circuit.

[0046] 3 may be provided in a device other than the control device 100 that controls the film thickness measurement unit U3. When some of the functions are provided in an external device other than the control device 100, the external device and the control device 100 work together to perform the functions described in the following embodiments. In such a case, the external device equipped with the functions corresponding to the control device 100 described in this embodiment and the remaining parts of the film thickness measurement system 1 described in this embodiment can function together as a film thickness measurement system.

[0047] [Film thickness measurement method] Next, a film thickness measurement method by the control device 100 will be described. The film thickness measurement method is a method related to measurement of the film thickness after film formation performed in the film thickness measurement unit U3. The film thickness measurement unit U3 measures the film thickness of the film formed on the wafer W after film formation. As described above, the film thickness measurement unit U3 has, for example, the imaging unit 33 and the spectroscopic measurement unit 40, and can acquire image data of the surface of the wafer W captured by the imaging unit 33 and spectroscopic spectrum data of the surface of the wafer W by the spectroscopic measurement unit 40. The control device 100 measures the film thickness based on these data. In the following description, it is assumed that the film thickness of a silicon nitride film is measured.

[0048] Prior to measuring the thickness of a silicon nitride film, the control device 100 acquires reference data and calibration data to be used in the measurement. FIG. 5 is a flow diagram showing an example of control by the control device (acquisition of reference data). FIG. 6 is a flow diagram showing an example of control by the control device (estimation of film thickness from spectral data). FIG. 7 is a flow diagram showing an example of control by the control device (acquisition of calibration data). FIG. 8 is a diagram showing an example of a position for acquiring spectral data of a reference wafer. FIG. 9 is a diagram showing an example of an area for acquiring color information of a calibration wafer.

[0049] [Get reference data] When acquiring the reference data, N (N is an integer of 2 or more) reference wafers W1 (see FIG. 8) on which a film to be measured, here a silicon nitride film, is formed are prepared in advance. The reference wafer W1 is a bare wafer on which no pattern is formed and on which a silicon nitride film is entirely formed. The thicknesses of the silicon nitride films are different among the N reference wafers W1. For example, five reference wafers W1 are prepared, and the thicknesses of the silicon nitride films in the respective reference wafers W1 are about 64 nm, about 66 nm, about 70 nm, about 72 nm, and about 74 nm, respectively. However, the thickness of the silicon nitride film of the reference wafer W1 does not need to be precise. The reference wafer W1 is an example of a first substrate, and the silicon nitride film formed on the reference wafer W1 is an example of a first film.

[0050] 5, the film thickness measurement unit 101 of the control device 100 first executes step S11. In step S11, one reference wafer W1 is loaded into the film thickness measurement unit U3. The reference wafer W1 is held by the holder 31.

[0051] Next, the spectroscopic data acquisition unit 102 of the control device 100 executes step S12. In step S12, the spectroscopic measurement unit 40 performs spectroscopic measurement at a plurality of measurement positions determined in advance on the surface of the reference wafer W1. As described above, the incident unit 41 of the spectroscopic measurement unit 40 is provided on a path through which the wafer W held by the holder 31, here the center of the reference wafer W1, passes when the holder 31 moves, so that the spectroscopic spectrum can be acquired at a plurality of positions along the radial direction of the reference wafer W1, including the center. In addition, the drive unit 32 rotates the holder 31, so that the spectroscopic measurement unit 40 can also acquire the spectroscopic spectrum at a plurality of positions along the circumferential direction of the reference wafer W1. Therefore, as shown in FIG. 8, the reflected light from a plurality of first positions P1 where a plurality of line segments passing through the center of the reference wafer W1 and a plurality of concentric circles intersect is incident on the incident unit 41. The spectroscope 43 performs measurement related to the spectroscopic spectrum of the light incident on the incident unit 41. As a result, the spectrometer 43 acquires P pieces of, for example, 49 pieces of spectroscopic data corresponding to the plurality of first positions P1 shown in FIG. 8. In this manner, spectroscopic data relating to the surface of the reference wafer W1 at the plurality of first positions P1 is acquired by using the spectrometer 43. The location and number of the first positions P1 can be appropriately changed depending on the interval of the spectroscopic measurement by the spectrometer 43 and the moving speed of the reference wafer W1 by the holder 31. The spectroscopic data acquired by the spectrometer 43 is held in the spectroscopic data acquisition unit 102 of the control device 100. In addition, when performing spectroscopic measurement, the center position of the holder 31 and the center position of the reference wafer W1 held by the holder 31 are identified from the image information, and the difference between them is corrected, so that the spectroscopic measurement unit 40 can be accurately aligned to each first position P1. The same applies to spectroscopic measurements of the calibration wafer W2 and the product wafer W3 described later.

[0052] Next, the reference film thickness acquisition unit 103 of the control device 100 executes step S13. In step S13, the film thickness of the silicon nitride film at each first position P1 where the spectroscopic measurement was performed is acquired from the spectroscopic spectrum data. Acquisition of the film thickness using the spectroscopic spectrum data utilizes the change in reflectance according to the film thickness of the surface film. When light is irradiated onto a wafer having a film formed on its surface, the light is reflected by the surface of the top film, or by the interface between the top film and the lower layer (film or wafer). Then, these lights are emitted as reflected light. That is, the reflected light contains two components of light with different phases. Also, when the film thickness of the surface increases, the phase difference increases. Therefore, when the film thickness changes, the degree of interference between the light reflected by the above-mentioned film surface and the light reflected by the interface with the lower layer changes. That is, the shape of the spectroscopic spectrum of the reflected light changes. The change in the spectroscopic spectrum according to the film thickness can be theoretically calculated. Therefore, the control device 100 stores information related to the shape of the spectroscopic spectrum according to the film thickness formed on the surface in advance. Then, the spectrum of reflected light obtained by irradiating the actual reference wafer W1 with light is compared with the previously stored information. This makes it possible to estimate the thickness of the film on the surface of the reference wafer W1. Information relating to the relationship between the film thickness and the shape of the spectrum used to estimate the film thickness is stored in the spectral information storage unit 109 of the control device 100.

[0053] 6 shows a method for calculating the film thickness from the spectral data. First, the result of the spectroscopic measurement, i.e., the spectral data, is obtained (step S21), and then the spectral data is compared with information stored in the spectral information storage unit 109, i.e., information related to the shape of the spectral spectrum corresponding to the theoretical film thickness (step S22). This makes it possible to estimate the film thickness of the region where the spectral data was obtained for each piece of spectral data (step S23). This makes it possible to estimate the film thickness for each piece of spectral data, i.e., at each first position P1 on the surface of the reference wafer W1.

[0054] Next, the film thickness measurement unit 101 of the control device 100 executes step S14. In step S14, the reference wafer W1 is unloaded from the film thickness measurement unit U3.

[0055] The control device 100 executes the processes of steps S11 to S14 for a predetermined number (N) of reference wafers W1 that have been prepared in advance (NO in step S15).

[0056] Then, when the processing for a predetermined number (N pieces) of reference wafers W1 prepared in advance is completed (YES in step S15), the film thickness measuring unit 101 of the control device 100 completes the processing for obtaining the reference data.

[0057] In this manner, the film thickness of the silicon nitride film at each of the first positions P1 is acquired as reference data for each of the N reference wafers W1 and stored in the reference film thickness acquisition unit 103 of the control device 100.

[0058] [Acquisition of calibration data] When acquiring calibration data, N calibration wafers W2 (see FIG. 9) on which the same pattern as the product wafer is formed are prepared in advance. The calibration wafer W2 is a wafer that imitates the product wafer, and in the initial state, the film to be measured, here a silicon nitride film, is not formed on the calibration wafer W2. Hereinafter, the calibration wafer W2 on which the film to be measured is not formed is referred to as a pre-film-formation calibration wafer W2. The calibration wafer W2 is an example of a second substrate.

[0059] 7, the film thickness measurement unit 101 of the control device 100 first executes step S31. In step S31, one pre-film formation calibration wafer W2 is loaded into the film thickness measurement unit U3. The pre-film formation calibration wafer W2 is held in the holder 31.

[0060] Next, the calibration image data acquisition unit 104 of the control device 100 executes step S32. In step S32, the imaging unit 33 images the surface of the pre-film-deposition calibration wafer W2. Specifically, the imaging unit 33 images the surface of the pre-film-deposition calibration wafer W2 while the drive unit 32 drives the holder 31 to move in a predetermined direction. This allows the imaging unit 33 to acquire pre-film-deposition image data relating to the surface of the pre-film-deposition calibration wafer W2. The pre-film-deposition image data is held in the calibration image data acquisition unit 104 of the control device 100.

[0061] Next, the calibration color information acquisition unit 105 of the control device 100 executes step S33. In the following description, the position on the calibration wafer W2 corresponding to each of the first positions P1 on the reference wafer W1 may be referred to as the "second position P2". In step S33, as shown in FIG. 9, for each second position P2 on the calibration wafer W2, pre-film-deposition color information of a plurality of first sub-regions SR1 in the first region R1 including the second position P2 included in the pre-film-deposition image data is acquired. The first region R1 is a predetermined region provided in advance for each second position P2. For example, the second position P2 is located at the center of the first region R1. The number of the first regions R1 is equal to the number of the first positions P1 or the number of the second positions, for example, 49. The plurality of first sub-regions SR1 are predetermined sub-regions provided in advance for each first region R1. For example, a total of 1600 first sub-regions SR1 are provided for each first region R1. In each of the first regions R1, 40 first sub-regions SR1 are arranged vertically, and 40 first sub-regions SR1 are arranged horizontally. Each first sub-region SR1 corresponds to, for example, each pixel of an imaging sensor (for example, a CCD sensor) of the imaging unit 33. That is, color information (for example, luminance) of each of the first sub-regions SR1 is acquired by a corresponding pixel of the imaging unit 33. The size of each of the first sub-regions SR1 is, for example, 150 μm×150 μm. The calibration color information acquisition unit 105 acquires, for example, the luminance of R (red), the luminance of G (green), and the luminance of B (blue) as pre-film-deposition color information from the pre-film-deposition image data. The pre-film-deposition color information is held in the calibration color information acquisition unit 105 of the control device 100.

[0062] Next, the film thickness measuring unit 101 of the control device 100 executes step S34. In step S34, the pre-deposition calibration wafer W2 is carried out from the film thickness measuring unit U3. A film to be measured having a film thickness similar to that of the film to be measured formed on the corresponding reference wafer W1 is formed on the pre-deposition calibration wafer W2 carried out from the film thickness measuring unit U3. Hereinafter, the calibration wafer W2 on which the film to be measured is formed is referred to as the post-deposition calibration wafer W2. It is preferable that the film thickness of the silicon nitride film formed on the post-deposition calibration wafer W2 is similar to that of the silicon nitride film formed on the corresponding reference wafer W1. For example, the film thicknesses of the silicon nitride films on the five post-deposition calibration wafers W2 are about 64 nm, about 66 nm, about 70 nm, about 72 nm, and about 74 nm, respectively. However, the film thicknesses of the silicon nitride films on the post-deposition calibration wafer W2 do not have to strictly match the above values. The silicon nitride film formed on the calibration wafer W2 is an example of the second film.

[0063] The control device 100 executes the processes of steps S31 to S34 for a predetermined number (N pieces) of pre-film-formation calibration wafers W2 that have been prepared in advance (NO in step S35).

[0064] Then, when the processing for the predetermined number (N pieces) of pre-deposition calibration wafers W2 prepared in advance is completed (YES in step S35), the film thickness measurement part 101 of the control device 100 executes step S36. In step S36, one post-deposition calibration wafer W2 is loaded into the film thickness measurement unit U3. The post-deposition calibration wafer W2 is held in the holding part 31.

[0065] Next, the calibration image data acquisition unit 104 of the control device 100 executes step S37. In step S37, the imaging unit 33 acquires an image of the surface of the post-film-deposition calibration wafer W2. Specifically, the imaging unit 33 acquires an image of the surface of the post-film-deposition calibration wafer W2 while the drive unit 32 is driving the holder 31 to move in a predetermined direction. As a result, post-film-deposition image data relating to the surface of the post-film-deposition calibration wafer W2 is acquired by the imaging unit 33. The post-film-deposition image data is held in the calibration image data acquisition unit 104 of the control device 100. The post-film-deposition image data of the post-film-deposition calibration wafer W2 is an example of first image data.

[0066] Next, the calibration color information acquisition unit 105 of the control device 100 executes step S38. In step S38, similar to the acquisition of pre-film-deposition color information of the pre-film-deposition calibration wafer W2, post-film-deposition color information of a plurality of first sub-regions SR1 in the first region R1 including the corresponding second position P2, which is included in the post-film-deposition image data, is acquired for each second position P2 of the post-film-deposition calibration wafer W2. The calibration color information acquisition unit 105 acquires, for example, the luminance of R (red), the luminance of G (green), and the luminance of B (blue) from the post-film-deposition image data as the post-film-deposition color information. The post-film-deposition color information is held in the calibration color information acquisition unit 105 of the control device 100. The post-film-deposition color information of the post-film-deposition calibration wafer W2 is an example of first color information.

[0067] Next, the film thickness measurement unit 101 of the control device 100 executes step S39. In step S39, the post-film-formation calibration wafer W2 is unloaded from the film thickness measurement unit U3.

[0068] The control device 100 repeats the processes of steps S36 to S39 a predetermined number (N pieces) of the post-film-formation calibration wafers W2 (NO in step S40).

[0069] Then, when the processing for the predetermined number (N) of post-film-deposition calibration wafers W2 prepared in advance is completed (YES in step S40), the correlation acquisition unit 106 of the control device 100 executes step S41. In step S41, for all first sub-regions SR1 in the plurality of first regions R1, the correlation between the film thickness of the silicon nitride film in the corresponding first region R1 and the calibration color information of the corresponding first sub-region SR1 is calculated, and the correlation acquisition unit 106 stores the correlation. To calculate the correlation, the film thickness of the silicon nitride film at the corresponding first position P1 on the reference wafer W1 held in the reference film thickness acquisition unit 103 is used as the film thickness of the silicon nitride film in the first region R1 of the post-film-deposition calibration wafer W2. The calibration color information is information indicating the difference between the pre-film-deposition color information and the post-film-deposition color information in each of the first sub-regions SR1. Specifically, the difference between the luminance value of R (red) acquired from the pre-film-deposition calibration wafer W2 and the luminance value of R (red) acquired from the post-film-deposition calibration wafer W2, the difference between the luminance value of G (green) acquired from the pre-film-deposition calibration wafer W2 and the luminance value of G (green) acquired from the post-film-deposition calibration wafer W2, and the difference between the luminance value of B (blue) acquired from the pre-film-deposition calibration wafer W2 and the luminance value of B (blue) acquired from the post-film-deposition calibration wafer W2 are used as the difference between the pre-film-deposition color information and the post-film-deposition color information (i.e., the calibration color information). In this embodiment, the difference between the luminance value acquired from the pre-film-deposition image data and the luminance value acquired from the post-film-deposition image data (i.e., the difference between the pre-film-deposition color information and the post-film-deposition color information) may be referred to as the "luminance difference" or "luminance value difference". FIG. 10 is a diagram showing an example of the relationship between the film thickness in the first sub-region SR1 and the luminance value difference. The relationship (correlation) shown in FIG. 10 can be acquired for each first sub-region SR1.

[0070] For example, the correlation acquisition unit 106 uses multiple regression analysis to calculate an equation expressing the correlation, assuming that the correlation between the calibration color information of the corresponding first sub-region SR1 and the film thickness of the silicon nitride film on the first region R1 in which the corresponding first sub-region SR1 is located is expressed by the following equation 1. The following equation 1 is an example of an equation expressing the correlation. In equation 1, y is the film thickness of the silicon nitride film, and x i(i is an integer between 1 and 3) is the luminance value difference in the first sub-region SR1. For example, x1, x2, and x3 are the luminance value difference of R (red), G (green), and B (blue), respectively. α is a constant, and β i is a multiple regression coefficient (sometimes simply referred to as a "coefficient" in this embodiment). The correlation is calculated (obtained) for each of the first sub-regions SR1 in all of the first regions R1.

[0071] y=α+Σβ i x i =α+β1x1+β2x2+β3x3...(Formula 1)

[0072] The following is an example of calculating the correlation between color information (calibration color information) and film thickness for an arbitrary sub-region of the calibration wafer (i.e., the constant α and the coefficient β i In the following, it is assumed that five calibration wafers W21, W22, W23, W24, and W25 are used, and five reference wafers W11, W12, W13, W14, and W15 are used to calculate the correlation between color information and film thickness. The definitions of terms used in the following description are the same as those described above. That is, the arbitrary sub-region of the calibration wafer is one of the first sub-regions SR1 included in the first region R1 of the calibration wafer, and the second position P2 of the first region R1 including the arbitrary sub-region corresponds to the first position P1 on the reference wafer.

[0073] The film thicknesses at the first positions of the reference wafers W11, W12, W13, W14, and W15 are T1, T2, T3, T4, and T5, respectively, and the film thicknesses at the first positions of the reference wafers W11, W12, W13, W14, and W15 are approximately the same as the film thicknesses at the second positions of the calibration wafers W21, W22, W23, W24, and W25, respectively. Furthermore, the color information (brightness value difference) of any sub-region of the calibration wafers W21, W22, W23, W24, and W25 is as follows:

[0074] The luminance difference of R (red) on the calibration wafer W21 is Lr1 The luminance difference of G (green) on the calibration wafer W21 is Lg1 The brightness difference of B (blue) on the calibration wafer W21 is Lb1. The luminance difference of R (red) on the calibration wafer W22 is Lr2 The luminance difference of G (green) on the calibration wafer W22 is Lg2 The brightness difference of B (blue) on the calibration wafer W22 is Lb2 The luminance difference of R (red) on the calibration wafer W23 is Lr3 The luminance difference of G (green) on the calibration wafer W23 is Lg3 The brightness difference of B (blue) on the calibration wafer W23 is Lb3 The luminance difference of R (red) on the calibration wafer W24 is Lr4 The luminance difference of G (green) on the calibration wafer W24 is Lg4 The brightness difference of B (blue) on the calibration wafer W24 is Lb4. The luminance difference of R (red) on the calibration wafer W25 is Lr5. The brightness difference of G (green) on the calibration wafer W25 is Lg5 The brightness difference of B (blue) on the calibration wafer W25 is Lb5.

[0075] Here, a multiple regression analysis is performed using the following five sets of data ((T1, Lr1, Lg1, Lb1), (T2, Lr2, Lg2, Lb2), (T3, Lr3, Lg3, Lb3), (T4, Lr4, Lg4, Lb4), (T5, Lr5, Lg5, Lb5)) to determine the constant α and coefficient β for any of the sub-regions of the calibration wafer. i (β1, β2, β3) is obtained. Constant α and coefficient β i A multiple regression analysis to obtain is performed for each first sub-region SR1.

[0076] An example of calculating the correlation between color information (calibration color information) and film thickness using multiple regression analysis has been described above. However, the method of obtaining the correlation between color information and film thickness is not limited to multiple regression analysis. The correlation between color information and film thickness may be obtained by using other known methods such as support vector machine (SVM), regression tree, nonlinear regression, Gaussian process regression (GPR), and regression analysis that takes overfitting into account, such as ridge regression, Lasso regression, and PLS regression.

[0077] After acquiring (calculating) the correlation, the film thickness measuring unit 101 of the control device 100 ends the process of acquiring the calibration data.

[0078] As described above, for each of the first sub-regions SR1 in all of the first regions R1, the correlation between the thickness of the silicon nitride film in the corresponding first region R1 and the calibration color information (brightness value difference) of the corresponding first sub-region SR1 is acquired and stored as calibration data in the correlation acquisition unit 106 of the control device 100. The correlation does not necessarily have to be stored in the form of a formula such as Equation 1. In addition, when the correlation is expressed by the above-mentioned Equation 1, the constant α and coefficient β in Equation 1 can be i A set of (β1, β2, β3) may be held in the correlation acquisition section 106 for each of the first sub-regions SR1.

[0079] [Film thickness measurement on product wafers] The control device 100 acquires the reference data and the calibration data as described above, and then measures the thickness of the silicon nitride film on the product wafer. Fig. 11 is a flow chart showing an example of control (film thickness measurement on the product wafer) by the control device. Fig. 12 is a diagram showing an example of an area for acquiring color information of the product wafer.

[0080] The film thickness measurement section 101 of the control device 100 executes step S51. In step S51, a product wafer W3 (see FIG. 12) on which a pattern is formed is carried into the film thickness measurement unit U3. In an initial state, the film to be measured, in this case a silicon nitride film, is not formed on the product wafer W3. Hereinafter, the product wafer W3 on which the film to be measured is not formed is referred to as a pre-film-formation product wafer W3. The pre-film-formation product wafer W3 is held in the holding section 31. The product wafer W3 is an example of a third substrate.

[0081] Next, the product image data acquisition unit 107 of the control device 100 executes step S52. In step S52, the imaging unit 33 acquires an image of the surface of the pre-film-deposition product wafer W3. Specifically, the imaging unit 33 acquires an image of the surface of the pre-film-deposition product wafer W3 while the drive unit 32 is driving the holder 31 to move in a predetermined direction. This allows the imaging unit 33 to acquire pre-film-deposition image data relating to the surface of the pre-film-deposition product wafer W3. The pre-film-deposition image data relating to the surface of the pre-film-deposition product wafer W3 is sometimes referred to as "pre-film-deposition image data of the pre-film-deposition product wafer W3." The pre-film-deposition image data of the pre-film-deposition product wafer W3 is held in the product image data acquisition unit 107 of the control device 100.

[0082] Next, the product color information acquisition unit 108 of the control device 100 executes step S53. In step S53, as shown in FIG. 12, for each second sub-region SR2 in the product wafer W3 corresponding to one of the plurality of first sub-regions SR1, pre-film-deposition color information of the pre-film-deposition product wafer W3 included in the pre-film-deposition image data of the pre-film-deposition product wafer W3 is acquired. The product color information acquisition unit 108 acquires, for example, the luminance of R (red), G (green), and B (blue) as the pre-film-deposition color information of the pre-film-deposition product wafer W3. The pre-film-deposition color information of the pre-film-deposition product wafer W3 is held in the product color information acquisition unit 108 of the control device 100.

[0083] Next, the film thickness measurement unit 101 of the control device 100 executes step S54. In step S54, the pre-film-formation product wafer W3 is carried out from the film thickness measurement unit U3. A film to be measured is formed on the pre-film-formation product wafer W3 carried out from the film thickness measurement unit U3 in one of the process modules PM1 to PM4. Hereinafter, the product wafer W3 on which the film to be measured (e.g., a silicon nitride film) is formed is referred to as the post-film-formation product wafer W3. The silicon nitride film formed on the product wafer W3 is an example of a third film.

[0084] Next, the film thickness measurement unit 101 of the control device 100 executes step S55. In step S55, one post-film-formation product wafer W3 is carried into the film thickness measurement unit U3. The post-film-formation product wafer W3 is held in the holder 31.

[0085] Next, the product image data acquisition unit 107 of the control device 100 executes step S56. In step S56, the imaging unit 33 acquires an image of the surface of the film-formed product wafer W3. Specifically, the imaging unit 33 acquires an image of the surface of the film-formed product wafer W3 while the drive unit 32 drives the holder 31 to move in a predetermined direction. As a result, the imaging unit 33 acquires post-film-formation image data relating to the surface of the film-formed product wafer W3. The post-film-formation image data relating to the surface of the film-formed product wafer W3 is sometimes referred to as "post-film-formation image data of the film-formed product wafer W3." The post-film-formation image data of the film-formed product wafer W3 is held in the product image data acquisition unit 107 of the control device 100. The post-film-formation image data of the film-formed product wafer W3 is an example of second image data.

[0086] Next, the product color information acquisition unit 108 of the control device 100 executes step S57. In step S57, similar to the acquisition of pre-film-deposition color information of the pre-film-deposition product wafer W3, post-film-deposition color information included in the post-film-deposition image data of the post-film-deposition product wafer W3 is acquired for each second sub-region SR2. The product color information acquisition unit 108 acquires, for example, the luminance of R (red), G (green), and B (blue) as the post-film-deposition color information of the post-film-deposition product wafer W3. The post-film-deposition color information of the post-film-deposition product wafer W3 is held in the product color information acquisition unit 108 of the control device 100. The post-film-deposition color information of the post-film-deposition product wafer W3 is an example of second color information.

[0087] Next, the film thickness estimation unit 110 of the control device 100 executes step S58. In step S58, the thickness of the silicon nitride film formed on the post-film-deposition product wafer W3 is estimated based on the correlation held in the correlation acquisition unit 106 and the pre-film-deposition color information of the pre-film-deposition product wafer W3 and the post-film-deposition color information of the post-film-deposition product wafer W3 held in the product color information acquisition unit 108. The estimation of the film thickness of the silicon nitride film is performed for each second region R2.

[0088] As a result of executing the process for acquiring the calibration data shown in FIG. 10, Equation 1 is obtained, which expresses the correlation between the film thickness and the calibration color information, for each of the first sub-regions SR1 in the (after film formation) calibration wafer W2. In step S58, first, the luminance value differences of R (red), G (green), and B (blue) are calculated for each of the second sub-regions SR2 of all the second regions R2, using the pre-film-formation color information of the pre-film-formation product wafer W3 and the post-film-formation color information of the post-film-formation product wafer W3, which are held in the product color information acquisition unit 108. Next, an estimated value (i.e., film thickness) is calculated for each of the second sub-regions SR2, using Equation 1 and the luminance value differences of R (red), G (green), and B (blue) of the second sub-region SR2. In the following description, the value calculated using Equation 1 and the luminance value differences of R (red), G (green), and B (blue) of the second sub-region SR2 may be referred to as the "estimated film thickness of the second sub-region SR2". When calculating the estimated film thickness of an arbitrary second sub-region SR2 among the multiple second sub-regions SR2 on the product wafer W3 after film formation, the formula (Formula 1) of the corresponding first sub-region SR1 (i.e., the first sub-region SR1 corresponding to the arbitrary second sub-region SR2) is selected, and the brightness value differences of R (red), G (green), and B (blue) of the arbitrary second sub-region SR2 are input into x1, x2, and x3 of the selected formula (Formula 1), respectively. Film thickness estimation is performed for each of the second sub-regions SR2 in the calibration wafer W2 (after film formation). Next, the film thickness on each second region R2 is estimated using the estimated film thickness of the second sub-region SR2. The film thickness on the arbitrary second region R2 is estimated by calculating a weighted average of the estimated film thicknesses of all the second sub-regions SR2 in the arbitrary second region R2. Assume that n (n is a natural number) second regions R2 are defined on the product wafer W3 (after film formation), and each second region R2 is composed of p (p is a natural number) second sub-regions SR2. The film thickness on the kth second region R2 (i.e., the weighted average of the estimated film thicknesses of all the second sub-regions SR2) is Y k (k is an integer satisfying 1≦k≦n). In this case, Y k is calculated using the following formula (Equation 2):

[0089]

number

[0090] In formula 2, y ki is the estimated film thickness of the i-th second sub-region SR2 in the k-th second region R2 (i is an integer ranging from 1 to p, and p is the number of second sub-regions in the second region), and ω ki is a weighting coefficient defined for each second sub-region SR2. In one embodiment, the multiple correlation coefficient is defined as ω ki It can be used as.

[0091] Next, the film thickness measurement unit 101 of the control device 100 executes step S59. In step S59, the film-formed product wafer W3 is unloaded from the film thickness measurement unit U3. The unloaded film-formed product wafer W3 is sent to, for example, a downstream processing module.

[0092] In this manner, the thickness of the film to be measured formed on the product wafer W3 is measured.

[0093] [Effect] In the film thickness measurement unit U3, the film thickness is obtained from the reference wafer W1 on which no pattern is formed based on the spectral data, and color information is obtained from the calibration wafer W2 simulating the product wafer W3 based on the image data, and the correlation between the film thickness and the color information is obtained. Then, when measuring the film thickness of the film to be measured formed on the product wafer W3, color information is obtained from the product wafer W3 based on the image data, and the film thickness is estimated using the correlation between the film thickness and the color information. Therefore, even if a pattern is formed on the product wafer W3, the film thickness of the film to be measured can be measured with high accuracy without being affected by the position of the die of the product wafer W3. In other words, the film thickness can be measured with high accuracy without recognizing the die of the product wafer W3.

[0094] Furthermore, since the spectroscopic measurement section 40 is provided in the film thickness measurement unit U3, film thickness measurements can be performed on all wafers W transported to the substrate processing system 20 before the film formation process and all wafers W after the film formation process in the substrate processing system 20 without removing them from the substrate processing system 20, compared to the case where film thickness information is obtained using an ellipsometer external to the film thickness measurement unit U3.

[0095] In addition, when the film to be measured is relatively thin, the film thickness measured by spectroscopic analysis may differ from the film thickness measured by using an ellipsometer. In such a case, for example, it is preferable to obtain a correlation between the film thickness measured by spectroscopic analysis and the film thickness measured by using an ellipsometer in advance, store this correlation in the spectroscopic information storage unit 109, and use this correlation when estimating the film thickness (step S23).

[0096] FIG. 13 is a diagram showing an example of the measurement result of the thickness of a film on a bare wafer. In this measurement, five samples S11 to S15, each having a silicon nitride film with a different thickness formed on a bare wafer, were prepared, and the thickness of each sample was measured by spectroscopic analysis and by using an ellipsometer at 49 measurement positions (first positions). FIG. 13 shows the measurement result of the thickness of the film by spectroscopic analysis (solid line) and the measurement result of the thickness of the film by using an ellipsometer (dashed line). The horizontal axis in FIG. 13 indicates the number of the measurement position. 1 to 49 on the horizontal axis indicate the measurement positions of the sample S11, 50 to 98 indicate the measurement positions of the sample S12, 99 to 147 indicate the measurement positions of the sample S13, 148 to 196 indicate the measurement positions of the sample S14, and 197 to 245 indicate the measurement positions of the sample S15. The vertical axis in FIG. 13 indicates the measurement results of the thickness of the film. FIG. 14 is a diagram showing the relationship between the thickness measured by using an ellipsometer and the thickness measured by spectroscopic analysis. The horizontal axis of Fig. 14 indicates the film thickness measured using an ellipsometer, and the vertical axis of Fig. 15 indicates the film thickness measured by spectroscopic analysis. Fig. 14 shows the results for 245 measurement positions.

[0097] 13 and 14, for each of samples S11 to S15, there was a certain difference between the film thickness measured by spectroscopic analysis and the film thickness measured by an ellipsometer at each measurement position. When the correlation shown in Fig. 14 was approximated by a linear equation, the root mean square error (RMSE) was 0.16 nm.

[0098] Here, a measurement example of a product wafer on which a pattern is formed will be described. In this example, calibration data was obtained using five sets of a reference wafer W1 and a calibration wafer W2, and the calibration data was used to verify the measurement results for four product wafers W3. Specifically, the film thickness of the film (silicon nitride film) to be measured was measured at 49 measurement positions (first positions) for five calibration wafers W2 (samples S21 to S25) and four product wafers W3 (samples S31 to S34). FIG. 15 is a diagram showing an example of the result of film thickness measurement. FIG. 15(a) shows the measurement results of the film thickness for five calibration wafers W2 (samples S21 to S25), and FIG. 15(b) shows the measurement results of the film thickness for four product wafers W3 (samples S31 to S34). The white circles in FIG. 15 indicate the average film thickness of the silicon nitride film obtained by spectroscopic analysis for each sample. The black circles in FIG. 15 indicate the average film thickness of the silicon nitride film measured for each sample using the film thickness measurement system of the above embodiment. The horizontal axis in Fig. 15 indicates the sample number, and the vertical axis in Fig. 15 indicates the film thickness measurement results.

[0099] In the example shown in Figure 15, the difference between the average film thickness of the silicon nitride film measured using the film thickness measurement system of the above embodiment and the average film thickness of the silicon nitride film obtained by spectroscopic analysis is extremely small not only for the calibration wafer W2 (samples S21 to S25) but also for the product wafer W3 (samples S31 to S34).

[0100] Fig. 16 is a diagram showing an example of the film thickness measurement results for sample S34. The horizontal axis of Fig. 16 indicates the film thickness measured by spectroscopic analysis, and the vertical axis of Fig. 16 indicates the film thickness measured using the film thickness measurement system. Fig. 16 shows the results for 49 measurement positions. When the correlation shown in Fig. 16 for sample S34 was approximated by a linear equation, the root mean square error (RMSE) was 0.6 nm.

[0101] The light source 44 and the incident portion 41 may be integrally formed.

[0102] The film thickness measurement system 1 can be used by being built in, for example, a film formation apparatus in which film formation and film thickness measurement are performed. Examples of the film formation apparatus include a coating and developing apparatus, a chemical vapor deposition (CVD) apparatus, a sputtering apparatus, an evaporation apparatus, and an atomic layer deposition (ALD) apparatus. The film thickness measurement system can be used by being built in, for example, an etching apparatus in which etching and film thickness measurement are performed. Examples of the etching apparatus include a plasma etching apparatus and an atomic layer etching (ALE) apparatus. The film thickness measurement system may also be arranged independently of the film formation apparatus or the etching apparatus, and may communicate the measurement results to the film formation apparatus or the etching apparatus. The film thickness measurement system 1 does not need to be arranged in the film formation apparatus or the etching apparatus, and may also be arranged independently of the film formation apparatus or the etching apparatus, and may communicate the measurement results to the film formation apparatus or the etching apparatus.

[0103] Film thickness measurement system 1 does not need to include spectroscopic measurement unit 40 , and spectroscopic data acquisition unit 102 may be configured to acquire spectroscopic data from outside film thickness measurement system 1 .

[0104] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0105] 20 Substrate Processing System 31 Holding part 33 Imaging unit 40 Spectrometry section 100 Control device 101 Film thickness measurement section 102 Spectroscopic data acquisition unit 103 Film thickness reference acquisition unit 104 Calibration image data acquisition unit 105 Calibration color information acquisition unit 106 Correlation acquisition unit 107 Product image data acquisition unit 108 Product color information acquisition unit 109 Spectral information storage section 110 Film Thickness Estimation Section U3 Film Thickness Measurement Unit

Claims

1. a holder configured to hold a substrate; an imaging unit configured to acquire image data of the surface of the substrate held by the holding unit; A control unit; having The control unit is receiving spectral data of light reflected at a first position on a surface of a first substrate for each of N first substrates (N is an integer of 2 or more) having first films with different film thicknesses; calculating a thickness of each of the first films at the first location using the spectroscopic data; the imaging unit acquires first image data of the surfaces of the N second substrates on which the first patterns and the second films are formed; For each of the N second substrates, the first image data is used to obtain first color information of a plurality of first sub-regions within a first region, the first region including a second position corresponding to the first position; for each of the plurality of first sub-regions, using the calculated thickness of each of the first films at the first locations as a thickness of each of the second films in the first region, and calculating a correlation between film thickness and color information using the first color information of the N second substrates; the imaging unit acquires second image data of a surface of a third substrate on which a second pattern and a third film are formed; using the second image data to obtain second color information for a plurality of second sub-regions within a second region on the third substrate, the second region corresponding to the first region and the plurality of second sub-regions corresponding to the plurality of first sub-regions; configured to estimate a thickness of the third film in the second region using the calculated correlation and the second color information of the plurality of second sub-regions; The second substrate is a substrate that mimics the third substrate.

2. a spectroscopic measurement unit configured to separate light reflected by a surface of the substrate held by the holder, The film thickness measurement system according to claim 1 , wherein the control unit is configured to control the spectroscopic measurement unit so as to obtain the spectroscopic data from the spectroscopic measurement unit.

3. Each of the first substrates is provided with a plurality of third locations; Each of the second substrates is provided with a plurality of fourth positions corresponding to the third positions, the plurality of fourth positions being included in a plurality of third regions of each of the second substrates, each of the plurality of third regions including a plurality of third sub-regions; each of the third substrates includes a plurality of fourth regions corresponding to the plurality of third regions, each of the plurality of fourth regions including a plurality of fourth sub-regions; The control unit is calculating a thickness of each of the first films at the plurality of third locations using the spectroscopic data; For each of the N second substrates, acquiring the first color information of the third sub-regions in the third regions using the first image data; calculating the correlation between film thickness and the color information for each of the plurality of third sub-regions of all of the plurality of third regions; for each of the plurality of fourth regions in the third substrate, acquiring the second color information of the plurality of fourth sub-regions using the second image data; The film thickness measurement system of claim 1 , configured to estimate a thickness of the third film in each of the plurality of fourth regions.

4. The control unit is calculating an estimated film thickness for each of the plurality of second sub-regions in the second region using the calculated correlation for the first sub-region and the color information for the first sub-region; calculating a weighted average of the estimated film thicknesses of each of the second sub-regions in the second region as the thickness of the third film in the second region; The film thickness measurement system of claim 1 , configured to estimate a thickness of the third film.

5. 5 . The film thickness measurement system according to claim 1 , wherein the imaging section includes an imaging sensor having a plurality of pixels, and the plurality of second sub-regions correspond to each of the pixels of the imaging sensor.

6. receiving spectral data of light reflected at a first position on a surface of a first substrate for each of N first substrates (N is an integer of 2 or more) having first films with different thicknesses; calculating a thickness of each of the first films at the first location using the spectroscopic data; acquiring first image data of the surfaces of the N second substrates on which the first patterns and the second films are formed; for each of the N second substrates, acquiring first color information of a plurality of first sub-regions within a first region using the first image data, the first region including second positions corresponding to the first positions; for each of the plurality of first sub-regions, using the calculated thickness of each of the first films at the first location as the thickness of each of the second films in the first region, and calculating a correlation between film thickness and color information using the first color information of the N second substrates; acquiring second image data of a surface of a third substrate on which the second pattern and the third film are formed; using the second image data to obtain second color information of a plurality of second sub-regions within a second region on the third substrate, the second region corresponding to the first region and the plurality of second sub-regions corresponding to the plurality of first sub-regions; estimating a thickness of the third film in the second region using the calculated correlation and the second color information of the second sub-regions; and having The second substrate is a substrate simulating the third substrate.

7. Each of the first substrates is provided with a plurality of third locations; Each of the second substrates is provided with a plurality of fourth positions corresponding to the third positions, the plurality of fourth positions being included in a plurality of third regions of each of the second substrates, each of the plurality of third regions including a plurality of third sub-regions; each of the third substrates includes a plurality of fourth regions corresponding to the plurality of third regions, each of the plurality of fourth regions including a plurality of fourth sub-regions; calculating a thickness of each of the first films at the first locations includes calculating a thickness of each of the first films at the plurality of third locations using the spectroscopic data; the step of acquiring the first color information includes a step of acquiring, for each of the N second substrates, the first color information of the third sub-regions in the third regions using the first image data; calculating the correlation includes calculating the correlation between film thickness and the color information for each of the third sub-regions of the third region; The step of acquiring the second color information includes acquiring the second color information of the plurality of fourth sub-regions using the second image data for each of the plurality of fourth regions in the third substrate; The film thickness measuring method according to claim 6 , wherein the step of estimating the thickness of the third film includes the step of estimating the thickness of the third film in each of the plurality of fourth regions.

8. The thickness of the third film is calculating an estimated film thickness for each of the plurality of second sub-regions in the second region using the calculated correlation for the first sub-region and the color information for the first sub-region; calculating a weighted average of the estimated film thickness for each of the second sub-regions in the second region; The film thickness measuring method according to claim 6 or 7, wherein the film thickness is estimated by the following formula.

9. A program for causing a computer to execute the film thickness measuring method according to any one of claims 6 to 8.

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