Film thickness measurement system, film thickness measurement method, and program product

Abstract

A film thickness measurement system acquires spectroscopic data related to a first position on a surface of each of N first substrates on which a first film having a film thickness different from each other is formed, acquires a film thickness of the first film at the first position for each of the N first substrates, acquires first image data by imaging a surface of each of N second substrates on which a second film having a film thickness different from each other is formed, acquires first color information in each of a plurality of first sub-areas in a first area for each of the N second substrates, acquires a correlation between a film thickness of the second film in the first area and the first color information in each of the plurality of first sub-areas in the first area, acquires second image data by imaging a surface of a third substrate on which a third film is formed using the imaging section, acquires second color information in each of a plurality of second sub-areas, and estimates a film thickness of the third film in a second area corresponding to the first area from the second color information in each of the plurality of second sub-areas and the correlation.

Description

Technical Field

[0001] This invention relates to film thickness measurement systems, film thickness measurement methods, and related products. Background Technology

[0002] Patent Document 1 discloses a method for calculating the film thickness of a film formed on a substrate by taking an image of the substrate surface.

[0003] <Prior art documents>

[0004] <Patent Documents>

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-215193 Summary of the Invention

[0006] <Problem to be solved by this invention>

[0007] The present invention provides a film thickness measurement system, film thickness measurement method and program product capable of measuring the film thickness of a film formed on a patterned substrate with high precision.

[0008] <Methods for solving problems>

[0009] One aspect of the film thickness measurement system of the present invention includes: a holding unit configured to hold a substrate; an imaging unit configured to capture an image of the surface of the substrate held by the holding unit and acquire image data; and a control unit configured to control the imaging unit. The control unit includes: a spectral data acquisition unit configured to acquire spectral data of light reflected at a first position on the surface of N first substrates having first films of different thicknesses, where N is an integer greater than or equal to 2; a first film thickness acquisition unit configured to calculate the film thickness of the first film at the first position for each of the N first substrates based on the spectral data; a first image data acquisition unit configured to acquire first image data of the surface of N second substrates held by the holding unit and having a second film formed thereon, the second film having a film thickness substantially the same as the first film; and a first color information acquisition unit configured to acquire first color information of a plurality of first sub-regions within a first region for each of the N second substrates using the first image data. The system comprises: color information, wherein the first region includes a second position corresponding to the first position; a correlation acquisition unit configured to use the calculated film thickness of each of the first films at the first position as the film thickness of each of the second films in the first region, and to use the first color information of the N second substrates to calculate the correlation between film thickness and color information for each of the plurality of first sub-regions; a second image data acquisition unit configured to use the imaging unit to acquire second image data of the surface of the third substrate held by the holding unit and on which the third film is formed; a second color information acquisition unit configured to use the second image data to acquire second color information of a plurality of second sub-regions in the second region on the third substrate, wherein the second region corresponds to the first region and the plurality of second sub-regions correspond to the plurality of first sub-regions; and an estimation unit configured to estimate the film thickness of the third film in the second region based on the calculated correlation and the second color information of the plurality of second sub-regions.

[0010] <The Effects of the Invention>

[0011] According to the present invention, the film thickness of a film formed on a patterned substrate can be measured with high precision. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating an example of the general configuration of a substrate processing system.

[0013] Figure 2 This is a schematic diagram illustrating an example of a film thickness measurement unit.

[0014] Figure 3This is a block diagram illustrating an example of the functional configuration of a control device.

[0015] Figure 4 This is a block diagram illustrating an example of the hardware configuration of a control device.

[0016] Figure 5 This is a flowchart illustrating an example of control based on a control device (for reference, data acquisition).

[0017] Figure 6 This is a flowchart illustrating an example of control based on a control device (estimated by film thickness from spectroscopic data).

[0018] Figure 7 This is a flowchart illustrating an example of control (acquisition of correction data) based on a control device.

[0019] Figure 8 This is a diagram showing an example of the location where the spectroscopic data of a reference wafer is obtained.

[0020] Figure 9 This is a diagram showing an example of the area where color information is obtained from the calibration wafer.

[0021] Figure 10 This is a diagram illustrating an example of the relationship between film thickness and brightness value difference in the first sub-region.

[0022] Figure 11 This is a flowchart illustrating an example of control based on a control device (film thickness measurement in a product wafer).

[0023] Figure 12 This is a diagram showing an example of the area where color information is obtained from a wafer used to produce a product.

[0024] Figure 13 This is a figure showing an example of the measurement results of the film thickness on a bare wafer.

[0025] Figure 14 This is a graph showing the relationship between the film thickness measured using an ellipsometer and the film thickness measured by spectrophotometry.

[0026] Figure 15 This is a figure showing an example of the results of film thickness measurement.

[0027] Figure 16 These are other examples of the results of film thickness measurements. Detailed Implementation

[0028] The embodiments will now be described in detail with reference to the accompanying drawings. It should be noted that in this specification and the drawings, elements having substantially the same function are sometimes omitted from repeated descriptions by assigning the same reference numerals.

[0029] [Substrate Processing System]

[0030] First, the substrate processing system will be described. This substrate processing system is used to form films such as silicon nitride films on substrates. The substrate to be processed is, for example, a semiconductor wafer W. Figure 1 This is a schematic diagram illustrating an example of the general configuration of a substrate processing system.

[0031] The substrate processing system 20 is located within a cleanroom. Around a roughly pentagonal platform or vacuum transport chamber PH extending along the depth of the device, four process modules PM1, PM2, PM3, and PM4, and two load locking modules LLM are arranged in a cluster. a LLM b Although the illustration is omitted, the substrate processing system 20 has a system controller for overseeing the overall operation of the control system.

[0032] More specifically, two process modules PM1 and PM2 are connected to the vacuum transport chamber PH via gate valves GV1 and GV2 at the long side of the left side of the diagram, respectively. Two process modules PM3 and PM4 are connected to the vacuum transport chamber PH via gate valves GV3 and GV4 at the long side of the right side of the diagram, respectively. The load locking module LLM... a ,LLM b Through the gate valve GV a GV b The two short sides, which extend in a figure-eight shape at the bottom of the diagram, are connected to the vacuum transport chamber PH.

[0033] Process modules PM1, PM2, PM3, and PM4 have vacuum chambers 10 that are kept in a constant depressurization state by means of dedicated exhaust devices (not shown). Typically, a wafer W is placed on a stage or base (not shown) located in the center of the chamber, and a desired film is formed using a specified force (processing gas, electricity, depressurization, etc.).

[0034] Load Locking Module (LLM) a LLM b Through the gate valve DV respectively c DV d It can also communicate with the atmospheric transport chamber of the loading transport chamber LM described later, and each load locking chamber 202 is provided with a stage or transfer stage (not shown) for temporarily holding the wafer W transferred between the loading transport chamber LM and the vacuum transport chamber PH.

[0035] The vacuum delivery chamber PH is connected to a dedicated vacuum exhaust system (not shown), and its interior is typically maintained at a constant pressure under reduced pressure. A pair of retractable delivery arms F are located within the chamber. a F b It also includes a single-piece vacuum conveying robot 204 capable of sliding, rotating, and lifting movements. This vacuum conveying robot 204 operates according to instructions from the conveying control unit 206 within process modules PM1 to PM4 and the load locking module LLM. a LLM b They move back and forth between them, thus transporting wafers W in single-piece units.

[0036] Adjacent to the loading and transport chamber LM is a loading port LP, an alignment mechanism ORT, and a film thickness measurement unit U3. The loading port LP is used to load and unload wafer cassettes CR, capable of holding, for example, a batch of 25 wafers W, between the loading port LP and an external transport vehicle. Here, the wafer cassette CR is constructed as a FOUP (Front Open Unified Pod), SMIF (Standard Mechanical Interface) box, etc. The alignment mechanism ORT is used to ensure that the notch or orientation plane of the wafer W is aligned with a specified position or orientation. For wafers W that have undergone film deposition in any of process modules PM1 to PM4 and have returned to the loading and transport chamber LM after all processing is complete, or for wafers W that have undergone periodic sampling processing, the film thickness measurement unit U3 measures the film thickness of the formed film.

[0037] The monolithic atmospheric conveying robot 210, located within the loading and conveying chamber LM, has a pair of retractable conveying arms F stacked in two layers. c F d It can move horizontally above the linear guide 214 of the linear motor 212, and can lift, rotate, and move according to instructions from the transport control unit 206 at the loading port LP, the orientation plane alignment mechanism ORT, and the load locking module LLM. a LLM b The wafer W is transported in single-wafer units by moving back and forth between the film thickness measurement unit U3 and the film thickness measurement unit U3.

[0038] Here, the basic wafer transport sequence for subjecting a wafer placed into the wafer cassette CR at the loading port LP to a series of processes within the cluster tool is described.

[0039] With the LP door 216 open, the atmospheric conveying robot 210 inside the loading and conveying chamber LM retrieves a wafer W from the wafer cassette CR above the loading port LP, and conveys the wafer W to the alignment mechanism ORT for alignment. After alignment is complete, it is transferred to the load locking module LLM. a ,LLM b Any of them (e.g., LLM) a Load locking module LLM for transfer destination. a The wafer W is received under atmospheric pressure, and after being moved in, the chamber is evacuated, so that the semiconductor wafer W is handed over to the vacuum transport chamber PH by the vacuum transport robot 204 under reduced pressure.

[0040] In this substrate processing system 20, as a system approach, the same type of film deposition apparatus can be used in all four process modules PM1 to PM4, and these process modules PM1 to PM4 can perform film deposition using the same scheme.

[0041] Vacuum transport robot 204 uses transport arm F a F b One of them will be the self-load locking module LLM a The extracted wafer W is moved into any one of the process modules PM1 to PM4. Within each of these modules, a film deposition process is performed under predetermined conditions (gas, pressure, electricity, time, etc.) based on a pre-set plan. After the film deposition process is complete, the vacuum transport robot 204 removes the wafer W from each of the process modules PM1 to PM4 and transports it to the load locking module LLM. a LLM b one of them.

[0042] If the wafer W that has undergone film deposition is moved into a load-locking module (e.g., LLM) b Then the load locking module LLM b The indoor self-reducing pressure state switches to atmospheric pressure state. Then, the atmospheric conveying robot 210 in the loading and conveying chamber LM switches from the atmospheric pressure state to the load locking module LLM. b Remove wafer W and move the processed wafer W into film thickness measurement unit U3.

[0043] Furthermore, if the film thickness measurement unit U3 finishes measuring and evaluating the film thickness of the wafer W, the atmospheric transport robot 210 will remove the wafer W from the film thickness measurement unit U3 and return the removed wafer W to the matching wafer cassette CR.

[0044] [Film Thickness Measurement System]

[0045] Next, the film thickness measurement system of the embodiment will be described. Figure 2 This is a schematic diagram illustrating an example of a film thickness measurement system. The film thickness measurement system 1 includes a control device 100 and a film thickness measurement unit U3.

[0046] [Film Thickness Measurement Unit]

[0047] The film thickness measurement unit U3 acquires information about the surface of the film formed on the substrate (e.g., semiconductor wafer W) of the object being processed, as well as information about the film thickness.

[0048] like Figure 2 As shown, the film thickness measurement unit U3 includes a housing 30, a holding part 31, a driving part 32, an imaging part 33, a light projection / reflection part 34, and a spectrophotometer 40. The holding part 31 holds the wafer W horizontally. The driving part 32, for example, uses an electric motor as a power source to move the holding part 31 along a horizontal linear path. The driving part 32 can also rotate the holding part 31 in the horizontal plane. The imaging part 33 is, for example, a camera 35, such as a CCD camera. The camera 35 is located at one end of the film thickness measurement unit U3 in the direction of movement of the holding part 31, and faces the other end in the same direction of movement. The light projection / reflection part 34 projects light into the imaging range and guides the reflected light from the imaging range to the camera 35. For example, the light projection / reflection part 34 has a semi-transparent mirror 36 and a light source 37. A semi-transparent mirror 36 is positioned at a higher level than the holding part 31 in the middle of the movement range of the drive part 32, and is used to reflect light from below to the camera 35 side. A light source 37 is positioned above the semi-transparent mirror 36, and illuminates light downward through the semi-transparent mirror 36.

[0049] The spectrometer 40 has the function of incident and dispersed light from the wafer W to obtain a spectroscopic spectrum. The spectrometer 40 includes an incident section 41 for incident light from the wafer W, a waveguide section 42 for guiding the light incident to the incident section 41, a spectrometer 43 for dispersing the light guided by the waveguide section 42 to obtain a spectroscopic spectrum, and a light source 44. The incident section 41 is configured such that light from the center of the wafer W can be incident when the wafer W, held by the holding section 31, moves under the drive of the driving section 32. That is, it is located at a position corresponding to the movement path of the center of the holding section 31, which moves under the drive of the driving section 32. Furthermore, the incident section 41 is mounted such that when the wafer W moves due to the movement of the holding section 31, the incident section 41 moves relative to the surface of the wafer W along the radial direction of the wafer W. Therefore, the spectrometer 40 can obtain spectroscopic spectra from multiple locations along the radial direction of the wafer W, including the center of the wafer W. Furthermore, by rotating the holding unit 31 via the driving unit 32, the spectrometer 40 can acquire spectroscopic spectra at multiple points along the circumference of the wafer W. The waveguide 42 is constructed, for example, by an optical fiber. The beam splitter 43 splits the incident light to obtain a spectroscopic spectrum including intensity information corresponding to each wavelength. The light source 44 illuminates the light downwards. Thus, the reflected light at the wafer W passes through the incident unit 41 and the waveguide 42 and is incident on the beam splitter 43.

[0050] It should be noted that the wavelength range of the spectroscopic spectrum obtained in the beam splitter 43 can be set, for example, to the wavelength range of visible light (380 nm to 780 nm). Therefore, by using a light source emitting visible light as the light source 44, and by splitting the light reflected from the light source 44 on the surface of the wafer W in the beam splitter 43, spectroscopic spectral data of the wavelength range of visible light can be obtained. It should be noted that the wavelength range of the spectroscopic spectrum obtained in the beam splitter 43 is not limited to the visible light range, and can also be set to include, for example, wavelengths of infrared and ultraviolet light. A suitable beam splitter 43 and light source 44 can be selected according to the wavelength range of the obtained spectroscopic spectral data.

[0051] The film thickness measurement unit U3 performs the following operations to acquire image data of the surface of wafer W. First, the drive unit 32 moves the holding unit 31. As a result, wafer W passes under the semi-transparent mirror 36. During this passage, reflected light from the surface of wafer W is sequentially sent to the camera 35. The camera 35 images the reflected light from the surface of wafer W, thereby acquiring image data of the surface of wafer W. If the film thickness formed on the surface of wafer W changes, the image data of the surface of wafer W captured by the camera 35 changes; for example, the color of the surface of wafer W changes depending on the film thickness. In other words, acquiring image data of the surface of wafer W is equivalent to acquiring information about the film thickness formed on the surface of wafer W. This will be explained in detail later.

[0052] Image data acquired by camera 35 is sent to control device 100. In control device 100, the film thickness of the film on the surface of wafer W can be estimated based on the image data, and the estimation result is saved in control device 100 as an inspection result.

[0053] Furthermore, light from the surface of wafer W is incident on the spectrometer 40 for spectroscopic measurement. When the drive unit 32 moves the holding unit 31, wafer W passes under the incident unit 41. During this passage, reflected light from multiple points on the surface of wafer W is incident on the incident unit 41 and then incident on the beam splitter 43 via the waveguide unit 42. The incident light is split in the beam splitter 43 to obtain spectroscopic spectral data. If the film thickness formed on the surface of wafer W changes, the spectroscopic spectrum changes accordingly, for example. That is, obtaining spectroscopic spectral data of the surface of wafer W is equivalent to obtaining information about the film thickness formed on the surface of wafer W. This will be explained in detail later.

[0054] The spectroscopic data obtained by the spectrometer 43 is sent to the control device 100. In the control device 100, the film thickness of the film on the surface of the wafer W can be estimated based on the spectroscopic data, and the estimation result is stored in the control device 100 as an inspection result.

[0055] [Control Device]

[0056] A detailed description of an example of the control device 100 is provided. Figure 3 This is a block diagram illustrating an example of the functional configuration of a control device. The control device 100 is used to control the various elements included in the film thickness measurement unit U3. The control device 100 can be set independently of the system controller of the substrate processing system 20. The control device 100 can also cooperate with or be integrated with the system controller of the substrate processing system 20.

[0057] like Figure 3 As shown, the control device 100 includes, in terms of function, a film thickness measuring unit 101, a spectroscopic 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 spectroscopic information storage unit 109, and a film thickness estimation unit 110.

[0058] The film thickness measurement unit 101 has a function for controlling the film thickness measurement operation of the product wafer in the film thickness measurement unit U3. During the film thickness measurement in the film thickness measurement unit U3, image data and spectroscopic data are acquired.

[0059] The spectroscopic data acquisition unit 102 has the function of acquiring and storing the spectroscopic spectral data of the surface of the reference wafer from the spectrometer 43 of the film thickness measurement unit U3. The spectroscopic spectral data stored in the spectroscopic data acquisition unit 102 is used to estimate the film thickness of the film formed on the reference wafer.

[0060] The reference film thickness acquisition unit 103 has the function of calculating the film thickness of the film formed on the reference wafer based on the spectroscopic spectral data stored in the spectroscopic data acquisition unit 102. Details of the film thickness calculation steps will be described later. The reference film thickness acquisition unit 103 is an example of a first film thickness acquisition unit.

[0061] The calibration image data acquisition unit 104 has the function of acquiring and storing image data obtained by photographing 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.

[0062] The color information acquisition unit 105 for calibration has the function of acquiring and storing color information contained in the image data stored in the image data acquisition unit 104 for calibration. Details of the steps for acquiring color information will be described later. The color information acquisition unit 105 for calibration is an example of a first color information acquisition unit.

[0063] The correlation acquisition unit 106 has the function of acquiring and storing the correlation between the film thickness and color information of the film being measured. Details of the steps for acquiring the correlation will be described later.

[0064] The product image data acquisition unit 107 has the function of acquiring and storing image data obtained by photographing 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.

[0065] The product color information acquisition unit 108 has the function of acquiring and storing color information contained in the image data stored in the product image data acquisition unit 107. Details of the steps for acquiring color information will be described later. The product color information acquisition unit 108 is an example of a second color information acquisition unit.

[0066] The spectroscopic information storage unit 109 has the function of storing the spectroscopic information used to calculate the film thickness from the spectroscopic spectral data. The spectroscopic spectral data obtained by the film thickness measurement unit U3 varies depending on the type and thickness of the film formed on the surface of the wafer W. Therefore, the spectroscopic information storage unit 109 stores information on the correspondence between film thickness and spectroscopic spectrum.

[0067] The film thickness estimation unit 110 estimates the film thickness of the film formed on the product wafer based on the color information stored in the product color information acquisition unit 108 and the correlation relationship stored in the correlation relationship acquisition unit 106. Details of the film thickness estimation steps will be described later. The film thickness estimation unit 110 is an example of an estimation unit.

[0068] The control device 100 consists of one or more control computers. Figure 4 This is a block diagram illustrating an example of the hardware configuration of a control device. For example, control device 100 has... Figure 4 The circuit 120 shown has one or more processors 121, memory 122, storage 123, and input / output ports 124. Memory 123 has a storage medium, such as a hard disk, that can be read by a computer. The storage medium stores a program for causing the control device 100 to perform the process steps described later. The storage medium can be a retrievable medium such as non-volatile semiconductor memory, a hard disk, or an optical disk. Memory 122 is used to temporarily store the program read from the storage medium of memory 123 and the calculation results based on processor 121. Processor 121 executes the above-mentioned program by working with memory 122, thereby constituting the aforementioned functional modules. Input / output ports 124 input and output electrical signals between the controlled component and the controlled component according to instructions from processor 121.

[0069] It should be noted that the hardware configuration of the control device 100 is not necessarily limited to the functional modules being composed of programs. For example, the functional modules of the control device 100 can be composed of dedicated logic circuits or integrated ASICs (Application Specific Integrated Circuits).

[0070] It should be noted that, Figure 3 Some of the functions shown can be located on a device different from the control device 100 used to control the film thickness measurement unit U3. In the case where some functions are located on an external device different from the control device 100, the external device cooperates with the control device 100 to perform the functions described in the following embodiments. Furthermore, in this case, the external device equipped with functions corresponding to the control device 100 described in this embodiment and the remaining portion of the film thickness measurement system 1 described in this embodiment can function as a film thickness measurement system integrated together.

[0071] [Method for Measuring Film Thickness]

[0072] Next, the film thickness measurement method based on the control device 100 will be described. The film thickness measurement method is a method for measuring the film thickness after film deposition, performed in the film thickness measurement unit U3. In the film thickness measurement unit U3, the film thickness of the film deposited on the wafer W after deposition is measured. As described above, the film thickness measurement unit U3 includes, for example, an imaging unit 33 and a spectrophotometer 40, thereby acquiring image data obtained by imaging the surface of the wafer W through the imaging unit 33, and acquiring spectrophotometric data of the surface of the wafer W through the spectrophotometer 40. In the control device 100, the film thickness is measured based on this data. In the following description, the film thickness of a silicon nitride film will be measured.

[0073] Before measuring the thickness of the silicon nitride film, the control device 100 acquires reference data and calibration data for the measurement. Figure 5 This is a flowchart illustrating an example of control based on a control device (for reference, data acquisition). Figure 6 This is a flowchart illustrating an example of control based on a control device (estimation of film thickness from self-spectral spectral data). Figure 7 This is a flowchart illustrating an example of control (acquisition of correction data) based on a control device. Figure 8 This is a diagram showing an example of the location where the spectroscopic data of a reference wafer is obtained. Figure 9 This is a diagram showing an example of the area where color information is obtained from the calibration wafer.

[0074] [Reference Data Acquisition]

[0075] When obtaining reference data, the film to be measured is prepared in advance. Here, N (N is an integer greater than 2) reference wafers W1 (reference) with silicon nitride films formed on them are prepared in advance. Figure 8 The reference wafer W1 is a wafer on which a silicon nitride film is integrally formed on an unpatterned bare wafer. The thickness of the silicon nitride film varies among the N reference wafers W1. For example, five reference wafers W1 are prepared, with silicon nitride film thicknesses of approximately 64 nm, 66 nm, 70 nm, 72 nm, and 74 nm, respectively. However, the thickness of the silicon nitride film on the reference wafers W1 may not be strictly fixed. 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.

[0076] like Figure 5As shown, the film thickness measurement unit 101 of the control device 100 first executes step S11. In step S11, a reference wafer W1 is moved into the film thickness measurement unit U3. The reference wafer W1 is held in the holding unit 31.

[0077] 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 measurements on multiple predetermined measurement positions on the surface of the reference wafer W1. As described above, since the incident portion 41 of the spectroscopic measurement unit 40 is positioned on the path passing through the center of the wafer W (here, the reference wafer W1) held by the holding portion 31 when the holding portion 31 moves, spectroscopic spectra at multiple radial locations along the reference wafer W1, including the center portion, can be obtained. Furthermore, by rotating the holding portion 31 using the drive portion 32, the spectroscopic measurement unit 40 can also obtain spectroscopic spectra at multiple circumferential locations along the reference wafer W1. Therefore, as... Figure 8 As shown, for example, reflected light from multiple first positions P1, where multiple line segments intersect multiple concentric circles at the center of the reference wafer W1, is incident on the incident section 41. The beam splitter 43 measures the spectroscopic spectrum of the light incident on the incident section 41. As a result, in the beam splitter 43, for example, a spectrum similar to... Figure 8 The diagram shows P (e.g., 49) spectroscopic spectral data corresponding to multiple first positions P1. Thus, by using the spectrometer 43, spectroscopic spectral data of the surface of the reference wafer W1 at the multiple first positions P1 are obtained. It should be noted that the position and number of the first positions P1 can be appropriately changed according to the interval of the spectroscopic measurement based on the spectrometer 43 and the moving speed of the reference wafer W1 based on the holding unit 31. The spectroscopic spectral data obtained by the spectrometer 43 is stored in the spectroscopic data acquisition unit 102 of the control device 100. It should be noted that during spectroscopic measurement, the center position of the holding unit 31 and the center position of the reference wafer W1 held by the holding unit 31 are determined from image information, and the difference between the two is corrected, thereby enabling the spectroscopic measurement unit 40 to be accurately aligned with each first position P1. The same applies to the spectroscopic measurement of the calibration wafer W2 and the product wafer W3, which will be described later.

[0078] 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 spectroscopic measurement has been performed is acquired from spectroscopic spectral data. The acquisition of film thickness using spectroscopic spectral data refers to utilizing a method based on the change in reflectivity of the film thickness on the surface. When light is irradiated onto a wafer on which the film is formed, the light is reflected at the surface of the uppermost film or at the interface between the uppermost film and its lower layer (film or wafer). This light is emitted as reflected light. That is, the reflected light includes two components of light with different phases. Furthermore, if the film thickness on the surface increases, the phase difference increases. Therefore, if the film thickness changes, the degree of interference between the light reflected at the film surface and the light reflected at 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 based on the film thickness can be theoretically calculated. Therefore, in the control device 100, information about the shape of the spectroscopic spectrum based on the film thickness of the film formed on the surface is stored in advance. Furthermore, the spectroscopic spectrum of the reflected light obtained by irradiating the actual reference wafer W1 is compared with the stored information. Thus, the film thickness of the film on the surface of the reference wafer W1 can be estimated. Information about the relationship between the film thickness and the shape of the spectroscopic spectrum used for film thickness estimation is stored in the spectroscopic information storage unit 109 of the control device 100.

[0079] The specific method for calculating film thickness from spectroscopic data is as follows: Figure 6 As shown. First, after obtaining the results of the spectroscopic measurement, i.e., obtaining the spectroscopic spectral data (step S21), the spectroscopic spectral data is compared with the information stored in the spectroscopic information storage unit 109, i.e., the information on the theoretical shape of the spectroscopic spectrum based on the film thickness (step S22). Therefore, the film thickness of the region where the spectroscopic spectral data was obtained can be estimated for each spectroscopic spectral data (step S23). Thus, the film thickness at each first position P1 on the surface of the reference wafer W1 can be estimated for each spectroscopic spectral data.

[0080] Next, the film thickness measurement unit 101 of the control device 100 executes step S14. In step S14, the reference wafer W1 is removed from the film thickness measurement unit U3.

[0081] The control device 100 performs the processing steps S11 to S14 (step S15 NO) on a predetermined number (N) of reference wafers W1 prepared in advance.

[0082] Furthermore, if the processing of the predetermined number (N) of reference wafers W1 is completed (YES in step S15), the film thickness measurement unit 101 of the control device 100 completes the processing of acquiring reference data.

[0083] Thus, in the reference film thickness acquisition unit 103 of the control device 100, for each of the N reference wafers W1, the film thickness of the silicon nitride film at each first position P1 as reference data acquisition is acquired and stored.

[0084] [Acquisition of calibration data]

[0085] When obtaining calibration data, prepare N calibration wafers W2 with the same pattern as the product wafer (refer to...). Figure 9 The calibration wafer W2 is a wafer that mimics the product wafer. In its initial state, no film (in this case, a silicon nitride film) is formed on the calibration wafer W2 as the object of measurement. Hereinafter, the calibration wafer W2 without the film as the object of measurement will be referred to as the pre-filming calibration wafer W2. The calibration wafer W2 is an example of a second substrate.

[0086] like Figure 7 As shown, the film thickness measurement unit 101 of the control device 100 first executes step S31. In step S31, a pre-film formation calibration wafer W2 is moved into the film thickness measurement unit U3. The pre-film formation calibration wafer W2 is held in the holding unit 31.

[0087] Next, the calibration image data acquisition unit 104 of the control device 100 executes step S32. In step S32, the surface of the pre-film deposition calibration wafer W2 is captured by the imaging unit 33. Specifically, while the holding unit 31 is moved in a predetermined direction under the drive of the driving unit 32, the surface of the pre-film deposition calibration wafer W2 is captured by the imaging unit 33. As a result, pre-film deposition image data of the surface of the pre-film deposition calibration wafer W2 is acquired in the imaging unit 33. The pre-film deposition image data is stored in the calibration image data acquisition unit 104 of the control device 100.

[0088] Next, the calibration color information acquisition unit 105 of the control device 100 executes step S33. In step S33, as... Figure 9As shown, for each second position P2 of a calibration wafer W2 corresponding to a first position P1 of a reference wafer W1, the pre-filming color information contained in the pre-filming image data of a plurality of first sub-regions SR1 within a first region R1 including that second position P2 is obtained. The first region R1 is a predetermined region set 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 first regions R1 is equal to the number of first positions P1 (e.g., 49). Furthermore, the plurality of first sub-regions SR1 are predetermined sub-regions set in advance for each first region R1; for example, 40×40 (1600 in total) first sub-regions SR1 are set for each first region R1. Each first sub-region SR1 corresponds, for example, to each pixel of the image sensor (e.g., a CCD sensor) of the imaging unit 33. The size of each first sub-region SR1 is, for example, 150μm×150μm. The calibration color information acquisition unit 105 obtains, for example, the brightness values ​​of R (red), G (green), and B (blue) as pre-filming color information. Color information before film formation is stored in the calibration color information acquisition unit 105 of the control device 100.

[0089] Next, the film thickness measurement unit 101 of the control device 100 executes step S34. In step S34, the pre-deposition calibration wafer W2 is removed from the film thickness measurement unit U3. The pre-deposition calibration wafer W2 removed from the film thickness measurement unit U3 has a film of the same thickness as the film to be measured formed on the reference wafer W1. Hereinafter, the calibration wafer W2 with the film to be measured formed is referred to as the post-deposition calibration wafer W2. The thickness of the silicon nitride film formed on the post-deposition calibration wafer W2 is equal to the thickness of the silicon nitride film formed on the reference wafer W1. For example, the thicknesses of the silicon nitride films in the five post-deposition calibration wafers W2 are approximately 64 nm, approximately 66 nm, approximately 70 nm, approximately 72 nm, and approximately 74 nm, respectively. However, the thickness of the silicon nitride film on the post-deposition calibration wafer W2 may not be precise. The silicon nitride film formed on the calibration wafer W2 is an example of the second film.

[0090] The control device 100 performs steps S31 to S34 (step S35 NO) on a predetermined number (N) of pre-prepared pre-film-forming calibration wafers W2.

[0091] Furthermore, if the processing of the predetermined number (N) of pre-prepared pre-deposition calibration wafers W2 is completed (YES in step S35), the film thickness measurement unit 101 of the control device 100 executes step S36. In step S36, one post-deposition calibration wafer W2 is moved into the film thickness measurement unit U3. The post-deposition calibration wafer W2 is held in the holding unit 31.

[0092] Next, the calibration image data acquisition unit 104 of the control device 100 executes step S37. In step S37, the surface of the post-film-forming calibration wafer W2 is imaged by the imaging unit 33. Specifically, the surface of the post-film-forming calibration wafer W2 is imaged by the imaging unit 33 while the holding unit 31 is moved in a predetermined direction under the drive of the driving unit 32. Thus, post-film-forming image data of the surface of the post-film-forming calibration wafer W2 is acquired in the imaging unit 33. The post-film-forming image data is held in the calibration image data acquisition unit 104 of the control device 100. The post-film-forming image data of the post-film-forming calibration wafer W2 is an example of the first image data.

[0093] Next, the calibration color information acquisition unit 105 of the control device 100 executes step S38. In step S38, similar to acquiring the pre-deposition color information of the pre-deposition calibration wafer W2, for each second position P2, the post-deposition color information contained in the post-deposition image data of a plurality of first sub-regions SR1 within the first region R1 including that second position P2 is acquired. The calibration color information acquisition unit 105 acquires, for example, the brightness values ​​of R (red), G (green), and B (blue) as post-deposition color information. The post-deposition color information is held in the calibration color information acquisition unit 105 of the control device 100. The post-deposition color information of the post-deposition calibration wafer W2 is an example of the first color information.

[0094] Next, the film thickness measurement unit 101 of the control device 100 executes step S39. In step S39, the post-film calibration wafer W2 is removed from the film thickness measurement unit U3.

[0095] The control device 100 performs steps S36 to S39 (step S40 NO) on a predetermined number (N) of pre-prepared post-film calibration wafers W2.

[0096] Furthermore, if the processing of the predetermined number (N) of post-film-forming calibration wafers W2 is completed (YES in step S40), the correlation acquisition unit 106 of the control device 100 executes step S41. In step S41, using the thickness of the silicon nitride film at the first position P1 stored in the reference thickness acquisition unit 103 as the thickness of the silicon nitride film in the first region R1, the correlation between the thickness of the silicon nitride film in the first region R1 and the calibration color information of each of the plurality of first sub-regions SR1 in the first region R1 is obtained, and the obtained correlation is stored in the correlation acquisition unit 106. For example, the calibration color information is color information representing the difference (brightness value difference) between the pre-film-forming color information and the post-film-forming color information in each first sub-region SR1. Specifically, the difference between the brightness value R (red) obtained from the pre-film-deposition calibration wafer W2 and the brightness value R (red) obtained from the post-film-deposition calibration wafer W2, the difference between the brightness value G (green) obtained from the pre-film-deposition calibration wafer W2 and the brightness value G (green) obtained from the post-film-deposition calibration wafer W2, and the difference between the brightness value B (blue) obtained from the pre-film-deposition calibration wafer W2 and the brightness value B (blue) obtained from the post-film-deposition calibration wafer W2 are used as the difference between the color information before film deposition and the color information after film deposition (i.e., the color information for calibration). In this embodiment, the difference between the brightness value obtained from the image data before film deposition and the brightness value obtained from the image data after film deposition (i.e., the difference between the color information before film deposition and the color information after film deposition) is called the "brightness difference" or "brightness value difference". Figure 10 This is a diagram illustrating an example of the relationship between film thickness and brightness value difference in the first sub-region SR1. This can be obtained for each first sub-region SR1. Figure 10 The relationship shown in the figure.

[0097] For example, based on the assumption of a correlation expressed by the following mathematical formula 1, the correlation acquisition unit 106 uses multiple regression analysis to calculate mathematical formulas representing the correlation between the corrected color information of the corresponding first sub-region SR1 and the film thickness of the silicon nitride film within the first region R1, wherein the corresponding first sub-region SR1 is located within the first region R1. Mathematical formula 1 is an example of a mathematical formula representing a correlation. In mathematical formula 1, y is the film thickness of the silicon nitride film, x... i (i is an integer from 1 to 3) represents the brightness difference of the first sub-region SR1. For example, x1, x2, and x3 are the brightness differences of R (red), G (green), and B (blue), respectively. Additionally, α is a constant, and β... i These are multiple regression coefficients (which can be simply referred to as "coefficients" in this embodiment). The correlation is calculated (obtained) for each first subregion SR1 in all first regions R1.

[0098] y=α+Σβ i x i =α+β1x1+β2x2+β3x3 ···(Mathematical formula 1)

[0099] The following will explain how to calculate (obtain) color information (correction color information) and film thickness (i.e., obtain the constant α and coefficient β) relative to a sub-region of the calibration wafer. i Examples of the correlation between color information and film thickness are given below. Hereinafter, it is assumed that five reference wafers W11, W12, W13, W14, and W15 are used, and five calibration wafers W21, W22, W23, W24, and W25 are used to calculate (obtain) the correlation between color information and film thickness. Furthermore, the definitions of terms used in the following description are the same as above. That is, a sub-region of the calibration wafer is a sub-region SR1 included in the first region R1 of the calibration wafer, and a second position P2 in the first region R1 including this sub-region corresponds to a first position P1 on the reference wafer.

[0100] Suppose that in one example, the film thicknesses at the first positions of reference wafers W11, W12, W13, W14, and W15 are T1, T2, T3, T4, and T5, respectively, and that the film thicknesses at the first positions of reference wafers W11, W12, W13, W14, and W15 are substantially equal to the film thicknesses at the second positions of calibration wafers W21, W22, W23, W24, and W25, respectively. Furthermore, suppose the color information (brightness value difference) of a certain sub-region of calibration wafers W21, W22, W23, W24, and W25 is as follows:

[0101] The difference in the brightness value of R (red) on the calibration wafer W21 is Lr1.

[0102] The difference in brightness value of G (green) on the calibration wafer W21 is Lg1.

[0103] The difference in brightness value of B (blue) on the calibration wafer W21 is Lb1.

[0104] The difference in the brightness value of R (red) on the calibration wafer W22 is Lr2.

[0105] The difference in brightness value of G (green) on the calibration wafer W22 is Lg2.

[0106] The difference in brightness value of B (blue) on the calibration wafer W22 is Lb2.

[0107] The difference in the brightness value of R (red) on the calibration wafer W23 is Lr3.

[0108] The difference in brightness value of G (green) on the calibration wafer W23 is Lg3.

[0109] The difference in brightness value of B (blue) on the calibration wafer W23 is Lb3.

[0110] The difference in the brightness value of R (red) on the calibration wafer W24 is Lr4.

[0111] The difference in brightness value of G (green) on the calibration wafer W24 is Lg4.

[0112] The difference in brightness value of B (blue) on the calibration wafer W24 is Lb4.

[0113] The difference in the brightness value of R (red) on the calibration wafer W25 is Lr5.

[0114] The difference in brightness value of G (green) on the calibration wafer W25 is Lg5.

[0115] The difference in brightness value of B (blue) on the calibration wafer W25 is Lb5.

[0116] In this case, by using the following five sets of data ((T1, Lr1, Lg1, Lb1), (T2, Lr2, Lg2, Lb2), (T3, Lr3, Lg3, Lb3), (T4, Lr4, Lg4, Lb4) and (T5, Lr5, Lg5, Lb5)), the constant α and coefficient β relative to a specific sub-region of the calibration wafer are obtained. i (β1, β2, β3). Furthermore, multiple regression analysis was performed on each subregion SR1 to obtain the constant α and coefficient βi.

[0117] The above illustrates an example of using multiple regression analysis to calculate (obtain) the correlation between color information (correction color information) and film thickness. However, calculating (obtaining) the correlation between color information and film thickness is not limited to multiple regression analysis. Other known methods can be used to obtain the correlation between color information and film thickness, such as SVM (support vector machine), regression trees, nonlinear regression, GPR (Gaussian Process regression), Ridge regression or Lasso regression considering overfitting, PLS, and other known methods.

[0118] After obtaining (calculating) the correlation, the film thickness measurement unit 101 of the control device 100 ends the processing of obtaining calibration data.

[0119] Thus, in the correlation acquisition unit 106 of the control device 100, the correlation between the thickness of the silicon nitride film in the first region R1 and the correction color information (brightness value difference) of each of the plurality of first sub-regions SR1 within the first region R1 is acquired and stored as correction data. This correlation is not necessarily stored in the format of a mathematical expression such as Formula 1. When the correlation is expressed by the aforementioned Formula 1, for each first sub-region SR1, a set of constants α and coefficients β in Formula 1... i (β1, β2, β3) can be stored in the relation acquisition section 106.

[0120] [Film thickness measurement in product wafers]

[0121] Based on the reference data and calibration data obtained as described above, the control device 100 measures the thickness of the silicon nitride film in the product wafer. Figure 11 This is a flowchart illustrating an example of control based on a control device (film thickness measurement in a product wafer). Figure 12 This is a diagram showing an example of the area where color information is obtained from a wafer used to produce a product.

[0122] The film thickness measuring unit 101 of the control device 100 executes step S51. In step S51, the patterned product is placed on a wafer W3 (refer to...). Figure 12 The film thickness measurement unit U3 is then loaded into the wafer. Initially, no film (in this case, a silicon nitride film) is formed on the product wafer W3, which is the object of measurement. Hereinafter, the product wafer W3 without a film for measurement will be referred to as the pre-film-forming product wafer W3. The pre-film-forming product wafer W3 is held in the holding section 31. The product wafer W3 is an example of a third substrate.

[0123] Next, the product image data acquisition unit 107 of the control device 100 executes step S52. In step S52, the surface of the product wafer W3 before film deposition is captured by the imaging unit 33. Specifically, while the holding unit 31 is moved in a predetermined direction under the drive of the driving unit 32, the surface of the product wafer W3 before film deposition is captured by the imaging unit 33. As a result, pre-film deposition image data of the surface of the product wafer W3 before film deposition is acquired in the imaging unit 33. The pre-film deposition image data related to the surface of the product wafer W3 before film deposition can also be referred to as "pre-film deposition image data of the product wafer W3 before film deposition". The pre-film deposition image data of the product wafer W3 before film deposition is stored in the product image data acquisition unit 107 of the control device 100.

[0124] Next, the product color information acquisition unit 108 of the control device 100 executes step S53. In step S53, as... Figure 12As shown, for each of the multiple second sub-regions SR2 corresponding to the multiple first sub-regions SR1, the pre-filming color information of the pre-filming product wafer W3 contained in the pre-filming image data of the pre-filming product wafer W3 is acquired. The product color information acquisition unit 108 acquires, for example, brightness values ​​of R (red), G (green), and B (blue) as the pre-filming color information of the pre-filming product wafer W3. The pre-filming color information of the pre-filming product wafer W3 is stored in the product color information acquisition unit 108 of the control device 100.

[0125] Next, the film thickness measurement unit 101 of the control device 100 executes step S54. In step S54, the pre-film-forming product wafer W3 is removed from the film thickness measurement unit U3. On the pre-film-forming product wafer W3 removed from the film thickness measurement unit U3, a film to be measured is formed in any of the process modules PM1 to PM4. Hereinafter, the product wafer W3 on which the film to be measured is formed will be referred to as the post-film-forming product wafer W3. The silicon nitride film formed on the product wafer W3 is an example of a third film.

[0126] Next, the film thickness measurement unit 101 of the control device 100 executes step S55. In step S55, one film-formed product wafer W3 is moved into the film thickness measurement unit U3. The film-formed product wafer W3 is held in the holding unit 31.

[0127] Next, the product image data acquisition unit 107 of the control device 100 executes step S56. In step S56, the surface of the product wafer W3 after film deposition is captured by the imaging unit 33. Specifically, while the holding unit 31 is moved in a predetermined direction under the drive of the driving unit 32, the surface of the product wafer W3 after film deposition is captured by the imaging unit 33. Thus, the post-film deposition image data of the surface of the product wafer W3 after film deposition is acquired in the imaging unit 33. The post-film deposition image data related to the surface of the product wafer W3 after film deposition can also be referred to as "post-film deposition image data of the product wafer W3 after film deposition". The post-film deposition image data of the product wafer W3 after film deposition is stored in the product image data acquisition unit 107 of the control device 100. The post-film deposition image data of the product wafer W3 after film deposition is an example of second image data.

[0128] Next, the product color information acquisition unit 108 of the control device 100 executes step S57. In step S57, similar to acquiring the pre-filming color information of the product wafer W3 before film deposition, for each second sub-region SR2, the post-filming color information of the product wafer W3 contained in the post-filming image data of the post-filming wafer W3 is acquired. The product color information acquisition unit 108 acquires, for example, brightness values ​​of R (red), G (green), and B (blue) as the post-filming color information of the product wafer W3. The post-filming color information of the product wafer W3 is held in the product color information acquisition unit 108 of the control device 100. The post-filming color information of the product wafer W3 is an example of second color information.

[0129] Next, the film thickness estimation unit 110 of the control device 100 executes step S58. In step S58, the film thickness of the silicon nitride film formed on the post-film-forming product wafer W3 is estimated based on the correlation relationships stored in the correlation relationship acquisition unit 106, and based on the color information of the pre-film-forming product wafer W3 and the post-film-forming product wafer W3 stored in the product color information acquisition unit 108, as well as the correlation relationships stored in the correlation relationship acquisition unit 106. The film thickness estimation of the silicon nitride film is performed in each second region R2.

[0130] As execution Figure 10As a result of the steps shown in the process of obtaining correction data, for each first sub-region SR1 in the (after film deposition) correction wafer W2, a mathematical formula 1 representing the correlation between film thickness and correction color information was obtained. In step S58, firstly, using 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 stored in the product color information acquisition unit 108, the brightness value differences of R (red), G (green), and B (blue) for each second sub-region SR2 of all second regions R2 are calculated. Next, for each second sub-region SR2, an estimated value (i.e., film thickness) is calculated using mathematical formula 1 and the corresponding brightness value differences of R (red), G (green), and B (blue) for the second sub-region SR2. In the following description, the value calculated using mathematical formula 1 and the brightness value differences of R (red), G (green), and B (blue) for the second sub-region SR2 is referred to as the "estimated film thickness of the second sub-region SR2". When calculating the estimated film thickness of a specific second sub-region SR2 among multiple second sub-regions SR2 on the wafer W3 for the product after film deposition, the equation (Equation 1) for the corresponding first sub-region SR1 (i.e., the sub-region SR1 corresponding to a specific second sub-region SR2) is selected, and the brightness differences of R (red), G (green), and B (blue) values ​​of a specific second sub-region SR2 are input into x1, x2, and x3 of the selected mathematical formula (Equation 1). For each second sub-region SR2 in the (post-film deposition) calibration wafer W2, the film thickness is estimated. Next, the film thickness of each second region R2 is estimated using the estimated film thickness of the second sub-region SR2. The film thickness of a specific second region R2 is estimated by calculating the weighted average of the estimated film thicknesses of all second sub-regions SR2 in a specific second region R2. Assume that n (n is a natural number) second regions R2 are defined in the product wafer W3 (after film deposition), and each second region R2 consists of p second sub-regions SR2 (p is a natural number). Furthermore, the film thickness of the k-th second region R2 is determined by Y. k Let k be an integer satisfying 1 ≤ k ≤ n. In this case, Y is calculated using the following mathematical expression (Mathematical Expression 2). k .

[0131] ...(Mathematical Formula 2)

[0132] 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 removed from the film thickness measurement unit U3. The removed film-formed product wafer W3 is, for example, sent to a subsequent processing module.

[0133] In this way, the film thickness of the film formed on the product wafer W3 is measured.

[0134] [effect]

[0135] In the film thickness measurement unit U3, the film thickness is obtained from the unpatterned reference wafer W1 based on spectroscopic data, and color information is obtained from the calibration wafer W2, which imitates the product wafer W3, based on image data. The correlation between film thickness and color information is then established. Furthermore, when measuring the film thickness of the target film formed on the product wafer W3, color information is obtained from the product wafer W3 based on image data, and the film thickness is estimated using the correlation between film thickness and color information. Therefore, even when no pattern is formed on the product wafer W3, the film thickness of the target film can be measured with high accuracy regardless of the position of the mold on the product wafer W3. In other words, film thickness can be measured with high accuracy even without identifying the mold on the product wafer W3.

[0136] Furthermore, since the spectrometer 40 is located in the film thickness measurement unit U3, compared to the case where the film thickness information is obtained by using an ellipsometer outside the film thickness measurement unit U3, the film thickness can be measured without removing the wafer W from the substrate processing system 20, both before the film deposition process and after the film deposition process in the substrate processing system 20.

[0137] It should be noted that when the film of the object being measured is relatively thin, the film thickness measured by spectrophotometry may differ from the film thickness measured using an ellipsometer. In such cases, it is preferable, for example, to obtain the correlation between the film thickness measured by spectrophotometry and the film thickness measured using an ellipsometer beforehand, and to store this correlation in the spectrophotometric information storage unit 109, so as to use the correlation when estimating the film thickness (step S23).

[0138] Figure 13 This is a figure illustrating an example of the measurement results of the film thickness on a bare wafer. In this measurement, five samples S11 to S15, on which silicon nitride films of different thicknesses were prepared to be formed on the bare wafer, and the film thickness was measured at 49 measurement positions (first positions) by both spectrophotometric analysis and ellipsometry. Figure 13 The figure shows the film thickness measurement results obtained by spectrophotometry (solid line) and the film thickness measurement results obtained using an ellipsometer (dashed line). Figure 13 The horizontal axis represents the measurement location number. 1-49 on the horizontal axis represent the measurement location of sample S11, 50-98 represent the measurement location of sample S12, 99-147 represent the measurement location of sample S13, 148-196 represent the measurement location of sample S14, and 197-245 represent the measurement location of sample S15. Figure 13 The vertical axis in the figure represents the measurement results of the film thickness. Figure 14This is a graph showing the relationship between the film thickness measured using an ellipsometer and the film thickness measured by spectrophotometry. Figure 14 The horizontal axis represents the film thickness measured using an ellipsometer. Figure 15 The vertical axis represents the film thickness as determined by spectrophotometry. Figure 14 The results for 245 measurement locations are shown.

[0139] exist Figure 13 as well as Figure 14 In the example shown, regardless of which of the samples S11 to S15 is being tested, a certain difference exists between the film thickness measured by spectrophotometry at each measurement location and the film thickness measured using an ellipsometry. Using a single-step method... Figure 14 The correlation shown is approximated, and the root mean square error (RMSE) is 0.16 nm.

[0140] Here, a measurement example of a patterned product wafer is described. In this example, five sets of reference wafers W1 and calibration wafers W2 were used to obtain calibration data, and the measurement results of four product wafers W3 were verified using the calibration data. Specifically, the film thickness of the film (silicon nitride film) of the test object was measured at 49 measurement positions (first position) for the five calibration wafers W2 (samples S21 to S25) and the four product wafers W3 (samples S31 to S34). Figure 15 This is a figure illustrating an example of the results of film thickness measurement. In Figure 15 In (a), the film thickness measurement results in five calibration wafers W2 (samples S21 to S25) are shown. Figure 15 In (b), the film thickness measurement results of four product wafers W3 (samples S31 to S34) are shown. Figure 15 The white circles in the diagram represent the average film thickness of the silicon nitride film obtained by spectrophotometry in each sample. Figure 15 The black circle in the figure represents the average film thickness of the silicon nitride film in each sample as measured using the film thickness measurement system described above. Figure 15 The horizontal axis in the diagram represents the sample number. Figure 15 The vertical axis in the figure represents the measurement results of the film thickness.

[0141] exist Figure 15 In the example shown, not only is the difference between the average film thickness of the silicon nitride film measured using the film thickness measurement system of the above embodiment in the calibration wafer W2 (samples S21 to S25) and the average film thickness of the silicon nitride film obtained by spectrophotometric analysis extremely small, but the difference between the average film thickness of the silicon nitride film measured using the film thickness measurement system of the above embodiment in the product wafer W3 (samples S31 to S34) and the average film thickness of the silicon nitride film obtained by spectrophotometric analysis is also extremely small.

[0142] Figure 16 This is a figure showing an example of the measurement results of the film thickness in sample S34. Figure 16 The horizontal axis represents the film thickness as determined by spectrophotometry. Figure 16 The vertical axis represents the film thickness measured using a film thickness measurement system. Figure 16 The results for 49 measurement locations are shown in the figure. For sample S34, a single-step method was used to measure... Figure 16 The correlation shown is approximated, and the root mean square error (RMSE) is 0.6 nm.

[0143] It should be noted that the light source 44 can be integrally formed with the incident part 41.

[0144] The film thickness measurement system 1 can be integrated into a film deposition apparatus for performing film deposition and film thickness measurement, for example. Examples of film deposition apparatuses include coating / developing apparatuses, chemical vapor deposition (CVD) apparatuses, sputtering apparatuses, evaporation apparatuses, and atomic layer deposition (ALD) apparatuses. The film thickness measurement system can also be integrated into an etching apparatus for performing etching and film thickness measurement, for example. Examples of etching apparatuses include plasma etching apparatuses and atomic layer etching (ALE) apparatuses. Alternatively, the film thickness measurement system can be configured independently of the film deposition apparatus or the etching apparatus, and the measurement results can be communicated and transmitted to the film deposition apparatus or the etching apparatus. Alternatively, the film thickness measurement system 1 does not need to be integrated into the film deposition apparatus or the etching apparatus; it can be configured independently of the film deposition apparatus or the etching apparatus, and the measurement results can be communicated and transmitted to the film deposition apparatus or the etching apparatus.

[0145] The film thickness measurement system 1 does not need to include a spectrophotometer 40, and the spectrophotometer data acquisition unit 102 can be configured to acquire spectrophotometer data from outside the film thickness measurement system 1.

[0146] The preferred embodiments have been described in detail above, but are not limited to the embodiments described above. Various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

Claims

1. A film thickness measurement system, comprising: A holding section configured to hold a substrate; The imaging unit is configured to capture images of the surface of the substrate held by the holding unit and acquire image data; and The control unit is configured to control the aforementioned camera unit. The aforementioned control unit has: The spectral data acquisition unit is configured to acquire spectral data of light reflected from the surfaces of N first substrates having first films of different thicknesses, at a first position, where N is an integer greater than or equal to 2. The first film thickness acquisition unit is configured to calculate the film thickness of the first film at the first position based on the above-mentioned spectral data for each of the above-mentioned N first substrates. The first image data acquisition unit is configured to use the above-described imaging unit to acquire first image data of the surfaces of N second substrates held by the above-described holding unit and on which a second film is formed, wherein the second film has a film thickness substantially the same as the first film. The first color information acquisition unit is configured to acquire first color information of a plurality of first sub-regions within a first region for each of the N second substrates using the first image data, wherein the first region includes a second position corresponding to the first position. The correlation acquisition unit is configured to use the calculated film thickness of each of the first films at the first position as the film thickness of each of the second films in the first region, and to use the first color information of the N second substrates to calculate the correlation between film thickness and color information for each of the plurality of first sub-regions. The second image data acquisition unit is configured to use the above-mentioned camera unit to acquire second image data of the surface of the third substrate held by the above-mentioned holding unit and on which a third film is formed; The second color information acquisition unit is configured to use the second image data to acquire second color information of a plurality of second sub-regions within a second region on the third substrate, wherein the second region corresponds to the first region, and the plurality of second sub-regions correspond to the plurality of first regions; and The estimation unit is configured to estimate the thickness of the third film in the second region based on the calculated correlation and the second color information of the plurality of second sub-regions.

2. The film thickness measuring system according to claim 1, wherein, It has a spectrophotometer configured to disperse light reflected from the surface of the substrate held by the holding portion, thereby obtaining spectrophotometric data. The above-mentioned spectroscopic data acquisition unit is configured to acquire the above-mentioned N spectroscopic data by using the above-mentioned spectroscopic measurement unit.

3. The film thickness measuring system according to claim 1, wherein, The aforementioned first film thickness acquisition unit is configured to calculate the film thickness of each of the aforementioned first films at a plurality of aforementioned first locations based on the aforementioned spectroscopic data. The first color information acquisition unit is configured to acquire, for each of the N second substrates, the first color information of a plurality of the first sub-regions within a plurality of the first regions using the first image data. The aforementioned correlation acquisition unit is configured to calculate the correlation between film thickness and color information for each of all the aforementioned first sub-regions within the aforementioned first regions. The second color information acquisition unit is configured to acquire the second color information of the plurality of second sub-regions for each of the plurality of second regions on the third substrate using the second image data. The aforementioned estimation unit is configured to estimate the thickness of the third membrane in each of the plurality of second regions.

4. The film thickness measuring system according to any one of claims 1 to 3, wherein, The above-mentioned estimation unit is configured to estimate the thickness of the third membrane by means of the following steps: Based on the aforementioned correlation calculated from the corresponding first sub-region and the color information of the corresponding first sub-region, the estimated film thickness of each of the plurality of second sub-regions within the second region is calculated, and Calculate the weighted average of the estimated film thickness of each of the plurality of second sub-regions within the second region, and use it as the film thickness of the third film within the second region.

5. The film thickness measuring system according to any one of claims 1 to 3, wherein, The aforementioned camera unit includes an image sensor with multiple pixels. The aforementioned plurality of second sub-regions correspond to each of the aforementioned plurality of pixels of the aforementioned image sensor.

6. A method for measuring film thickness, comprising: The process of acquiring spectral data acquires spectral data of light reflected from the surfaces of N first substrates having first films of different thicknesses, at first positions, where N is an integer greater than or equal to 2. The process of obtaining the thickness of the first film involves calculating the thickness of the first film at the first location for each of the N first substrates based on the aforementioned spectral data. The first image data acquisition process acquires first image data of the surfaces of N second substrates held by the holding portion and on which a second film is formed, wherein the second film has substantially the same film thickness as the first film. The first color information acquisition process is configured to acquire first color information of a plurality of first sub-regions within a first region for each of the N second substrates using the first image data, wherein the first region includes a second position corresponding to the first position. The correlation acquisition process uses the calculated film thickness of each of the first films at the first location as the film thickness of each of the second films in the first region, and uses the first color information of the N second substrates to calculate the correlation between film thickness and color information for each of the plurality of first sub-regions. The second image data acquisition process acquires second image data of the surface of the third substrate held by the aforementioned holding portion and on which a third film is formed; The second color information acquisition process uses the aforementioned second image data to acquire second color information of a plurality of second sub-regions within the second region on the third substrate, wherein the second region corresponds to the first region, and the plurality of second sub-regions correspond to the plurality of first regions; and The thickness estimation process of the third membrane is to estimate the thickness of the third membrane in the second region based on the calculated correlation and the second color information of the plurality of second sub-regions.

7. The film thickness measurement method according to claim 6, wherein, The process of obtaining the thickness of the first membrane includes: calculating the thickness of the first membrane at each of the plurality of the aforementioned first locations based on the aforementioned spectroscopic data. The aforementioned first color information acquisition process includes: for each of the N second substrates, using the aforementioned first image data, acquiring the first color information of multiple first sub-regions within multiple first regions. The aforementioned correlation acquisition process includes: for each of the plurality ... The aforementioned second color information acquisition process includes: for each of the plurality of second regions on the third substrate, using the aforementioned second image data, to acquire the second color information of the plurality of second sub-regions. The process for estimating the thickness of the third membrane includes estimating the thickness of the third membrane in each of the plurality of second regions.

8. The film thickness measurement method according to claim 6 or 7, wherein, The thickness estimation process for the third membrane mentioned above includes: Based on the aforementioned correlation calculated for the corresponding first sub-region and the color information of the corresponding first sub-region, the estimated film thickness of each of the plurality of second sub-regions within the second region is calculated; and Calculate the weighted average of the estimated film thickness of each of the plurality of second sub-regions within the second region, and use it as the film thickness of the third film within the second region.

9. A program product, characterized in that, The program product enables a computer to perform the film thickness measurement method according to any one of claims 6 to 8.

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