Measurement method, measurement device, and substrate processing device

Abstract

To determine the thickness of a film formed on a substrate from a spectrum showing the absorption or reflection characteristics obtained by irradiating the substrate with light.SOLUTION: A method includes the steps of: moving a substrate on which a film is formed while irradiating it with light; acquiring a dataset of characteristic spectra showing reflection or absorption characteristics at a plurality of positions along a trajectory of the light radiated onto the substrate; selecting the characteristic spectra acquired within an effective measurement section from the dataset; and determining the film thickness of a film formed on the substrate from the value at a singular point of the selected characteristic spectrum, when the characteristic spectra have been acquired at different positions on the substrate and a wavelength whose value is stable regardless of the light irradiation position is called a singular point, on the basis of a correspondence between the singular point and the film thickness of the film.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a measurement method, a measurement apparatus, and a substrate processing apparatus. [Background technology]

[0002] In a substrate processing apparatus, after a film is formed on a substrate such as a wafer, the film is sometimes inspected to determine whether it has a predetermined thickness and whether there are any abnormalities such as voids (gaps) inside the film. Patent Document 1 describes a method of detecting defective filling, in which a film is not properly filled into a plurality of minute recesses formed on a substrate, resulting in the formation of voids, by spectroscopic measurement using a transmission method or a reflection method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-100573 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can determine the film thickness of a film formed on a substrate from a spectrum that indicates the absorption or reflection characteristics obtained by irradiating the substrate with light. [Means for solving the problem]

[0005] The disclosed method is a method for measuring a film thickness of a substrate, comprising the steps of: a step of moving a light source relative to a substrate on which a film has been formed while irradiating the substrate with light, and acquiring a data set of characteristic spectra that indicate reflection or absorption characteristics at a plurality of positions on a trajectory of the light irradiated onto the substrate; selecting, from the data set, the characteristic spectrum acquired in an effective measurement section, which is a section in which the value of the characteristic spectrum at a predetermined wavelength falls within a predetermined allowable variation range between a plurality of positions on the trajectory; When the characteristic spectrum is acquired at different positions within the surface of the substrate, a wavelength whose value in the characteristic spectrum is within a predetermined range regardless of the position of the light irradiation is called a singular point, and based on a correspondence relationship between the singular point and the film thickness obtained in advance, the method includes a step of determining the film thickness of the film formed on the substrate from the value at the singular point of the selected characteristic spectrum. [Effects of the Invention]

[0006] According to the present disclosure, the thickness of a film formed on a substrate can be determined from a spectrum indicating the absorption or reflection characteristics obtained by irradiating a substrate with light. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a structural diagram showing an inspection device according to a first embodiment. [Figure 2] FIG. 2 is a configuration diagram showing a control device in the first embodiment. [Figure 3A] 2 is a partial plan view illustrating a substrate on which film thickness measurement is performed in the first embodiment. FIG. [Figure 3B] FIG. 3B is an enlarged longitudinal cross-sectional view of a portion of FIG. 3A. [Figure 4] 10 is a graph illustrating the reflectance spectra in pattern regions T1 and T2. [Figure 5] 10 is a graph illustrating the change in thickness of a SiN film relative to a singular point. [Figure 6] 10 is a graph showing an example in which a singular point does not appear as an intersection point of the reflectance spectrum. [Figure 7] 1 is a flowchart showing film thickness measurement. [Figure 8] FIG. 1 is a plan view showing a film forming processing system. [Figure 9]FIG. 2 is a vertical cross-sectional side view showing a film forming module. [Figure 10] FIG. 10 is a structural diagram showing an inspection device according to a second embodiment. [Figure 11] FIG. 1 is an explanatory diagram showing the principle of spectroscopic measurement using HSC. [Figure 12] FIG. 10 is a partial plan view showing an irradiation range in which spectroscopic measurement is performed in the second embodiment. [Figure 13] 10 is a graph showing a characteristic spectrum obtained by spectroscopic measurement according to the second embodiment. [Figure 14] 10 is a graph showing reflectance spectra obtained by spectroscopic measurement at different illuminance intensities. [Figure 15] FIG. 1 is a vertical cross-sectional side view showing an example of a film forming module provided with an inspection device using an HSC. [Figure 16] FIG. 2 is a cross-sectional plan view showing the film forming module. [Figure 17A] 1 is a graph showing the experimental results of Example 1-1. [Figure 17B] 1 is a graph showing the experimental results of Example 1-2. [Figure 18] 1 is a graph showing the experimental results of Examples 1-3. [Figure 19A] FIG. 1 is a first explanatory diagram showing the results of consideration based on the first embodiment. [Figure 19B] FIG. 2 is a second explanatory diagram showing the results of the study based on the first embodiment. [Figure 20] FIG. 10 is a plan view showing spectroscopic measurement in Example 2. [Figure 21A] 1 is a first graph showing the experimental results of Example 2. [Figure 21B] 10 is a second graph showing the experimental results of Example 2. [Figure 22] 10 is a table summarizing the conditions for spectroscopic measurement in Example 3. [Figure 23] 1 is a first graph showing the results of Example 3. [Figure 24] 2 is a second graph showing the results of Example 4. [Figure 25] FIG. 13 is a top perspective view showing a rotary table on which a substrate to be subjected to spectroscopic measurement is placed in Example 5. [Figure 26] 10 is a first graph showing the experimental results of Example 5. [Figure 27] 2 is a second graph showing the experimental results of Example 5. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) The inspection apparatus 1, which is an apparatus for measuring film thickness according to the first embodiment, will be described in detail below with reference to the drawings. The inspection apparatus 1 according to the first embodiment is for measuring the film thickness of a surface film 33 using a regular pattern (hereinafter simply referred to as "pattern") formed on a substrate W. It has the function of measuring the film thickness by irradiating the surface of the substrate W with a measurement light while moving it over the surface, performing spectroscopic measurement, and measuring the film thickness. FIG. 1 is a structural diagram showing the inspection apparatus 1 according to the first embodiment. FIG. 2 is a configuration diagram showing a control device 100 according to the first embodiment. The inspection apparatus 1 according to the first embodiment is disposed, for example, in a film formation processing system 10 that performs a film formation process (described later), and inspects the substrate W after film formation together with the control device 100 that controls the film formation process of the film formation processing system 10. It should be noted that the first embodiment may be described using an XYZ coordinate system, as appropriately shown in each drawing.

[0009] The substrate W, whose plan view is illustrated in FIG. 3A, is a simplified illustration for ease of understanding of a substrate on which a pattern is formed, such as a DRAM or NAND flash, and may differ from the actual pattern formed on the substrate. FIG. 3B is an enlarged longitudinal cross-sectional view of a portion of FIG. 3A. The surface of the substrate W is provided with multiple concave-convex pattern regions T1 (circuit pattern formation areas), such as cell arrays, in which concave-convex patterns 32 are regularly repeated. The concave-convex pattern regions T1 on this substrate W are regions in which the aforementioned patterns are formed, and are arranged, for example, in a 3×3 matrix along the X and Y directions. Around these nine concave-convex pattern regions T1, flat pattern regions T2 composed of flat patterns 34 with a generally flat surface are arranged. On the X-direction side of each concave-convex pattern region T1, another relatively narrow pattern region T3 composed of a concave-convex pattern different from the concave-convex pattern 32 of the concave-convex pattern region T1 is provided. The gap between adjacent concave-convex pattern regions T1 in the Y direction is a flat pattern region T2 (flat area) in which the flat pattern 34 is formed. The following description focuses on the concave-convex pattern region T1 and the flat pattern region T2, but the other pattern region T3 may be treated as a circuit pattern separate from the concave-convex pattern region T1. In this case, the following description can be applied on the assumption that two different types of circuit pattern forming areas (convex-convex pattern region T1, other pattern region T3) and a flat area (flat pattern region T2) are formed on the surface of the substrate W.

[0010] The concave-convex pattern 32 and flat pattern 34 in the concave-convex pattern region T1 are formed by, for example, etching the surface of the base layer 31 that constitutes the surface of the substrate W. A surface film 33 is formed uniformly on the surface of the substrate W over substantially the entire surface of the substrate W that is constituted by the pattern regions T1 and T2 through a film formation process in the film formation processing system 10. The base layer 31 is made of, for example, silicon (Si), which also constitutes the substrate W. The surface film 33 is, for example, a silicon nitride (SiN) film or a silicon oxide (SiO) film.

[0011] As shown in FIG. 3A , the inspection apparatus 1 performs spectroscopic measurement of the reflected light from the substrate W while moving the measurement light, which is illuminated on the surface of the substrate W using a general light source, for example, including ultraviolet to infrared light, relative to the substrate W, so as to form a predetermined trajectory. This measurement light is continuously irradiated during this moving measurement, and the reflected light is continuously received. The measurement control unit 133 of the control unit 115 (described later) controls the spectroscopic measurement of the received reflected light at a predetermined timing so that the trajectory of the continuous measurement light is separated into multiple irradiation ranges R. The trajectory of the irradiation range R thus defined can be arbitrarily set as long as it crosses the concave-convex pattern region T1 and the flat pattern region T2 and can pass through at least one pattern region T1 and at least one flat pattern region T2 for spectroscopic measurement. Therefore, the irradiation range R may be moved so as to form the trajectory C1 shown in white in FIG. 3A as long as it passes through the surface of the substrate W on which these pattern regions T1 and T2 are formed. The irradiation range R may be moved so as to form a trajectory C2 shown in black in the figure.

[0012] By moving and measuring along the trajectory C (C1, C2) that can be set freely in this way, a data set 122 (FIG. 2) that will be described later, which is a reflectance spectrum (characteristic spectrum) at each position, is acquired. The data set 122, for example, associates each acquired reflectance spectrum with information about the respective measurement positions. The information about the measurement positions is, for example, a combination of the irradiation interval of the measurement light and the order of measurements, or may simply be the order of measurements.

[0013] The film thickness in the concave-convex pattern region T1 is determined by performing the measurement process described below using the reflectance spectrum of the data set 122. Such film thickness measurement is performed on the surface film 33 on any of the concave-convex pattern regions T1, and it is also possible to inspect whether the surface film 33 is formed to an appropriate thickness without including, for example, voids (air gaps).

[0014] 1, the inspection device 1 includes a measurement unit (inspection unit) 11 for performing spectroscopic measurement, a stage 21 on which a substrate W is placed, and a control device 100. The measurement unit 11 includes a collimator lens 12, a coaxial probe 13 that irradiates measurement light via the collimator lens 12 and receives reflected light, an illuminator 14, and a measuring instrument 15 for spectroscopic measurement. The measurement unit 11 also includes a movement mechanism (not shown) that can displace the positions of the collimator lens 12 and the coaxial probe 13 in the X, Y, and Z directions.

[0015] The irradiator 14 incorporates a light source for emitting measurement light in the wavelength range from visible light to ultraviolet light used in film thickness measurement in the irradiation area R, as well as optical elements such as mirrors and lenses. The coaxial probe 13 is composed of a center portion for irradiating light and an outer portion for receiving light, with the center portion connected to the irradiator 14 and the outer portion connected to the measuring instrument 15 by optical fibers 16. The measurement light emitted from the coaxial probe 13 irradiates the irradiation area R on the surface of the substrate W composed of pattern areas T1 and T2, and the reflected light from the irradiation area R is detected by the measuring instrument 15 via the outer portion of the coaxial probe 13 and the optical fiber 16, and the reflectance or absorbance spectrum is measured.

[0016] The coaxial probe 13 shown in FIG. 1 can emit measurement light and receive reflected light from a common position via a collimator lens 12. The irradiation area R is the area on the substrate W that is irradiated with the flashing measurement light during the irradiation period. The irradiation area R must be set to a size that enables effective film thickness measurement on the substrate W. In other words, if the entire irradiation area R is not positioned within each of the pattern areas T1 and T2 to be measured, spectroscopic measurement that fully reflects the characteristics of the pattern areas T1 and T2 cannot be performed. For example, in spectroscopic measurement of the uneven pattern area T1, the irradiation area R must include only the uneven pattern area T1 and not the other pattern areas T2 and T3. In addition, in spectroscopic measurement of the flat pattern area T2, the irradiation area R must include only the flat pattern area T2 and not the other pattern areas T1 and T3. Hereinafter, for example, "the entire irradiation area R is positioned within the uneven pattern area T1" may also be referred to as "the irradiation area R is appropriately positioned within the uneven pattern area T1."

[0017] The size of the irradiation area R can be adjusted by the distance between the coaxial probe 13 and the collimator lens 12 and the distance between the collimator lens 12 and the substrate W. Meanwhile, the irradiation areas R formed while moving need to be appropriately arranged in multiple consecutive locations (three or more locations in the example described below) within the concave-convex pattern area T1 and the flat pattern area T2. Therefore, for example, the area of ​​the irradiation area R is adjusted in accordance with the processing timing of the reflected light to be measured by spectroscopically and the moving speed of the irradiation area R, and the size is adjusted to be less than half (one-half) of the area of ​​the concave-convex pattern area T1 and less than half of the area of ​​the flat pattern area T2. For example, when three or more irradiation areas R are appropriately arranged in each of the pattern areas T1 and T2, the size of the irradiation area R is adjusted to be less than one-third of the area of ​​the concave-convex pattern area T1 and less than one-third of the area of ​​the flat pattern area T2. The above-described control of the moving measurement is performed by a measurement control unit 132 (described later) of the control device 100 (described later).

[0018] Fig. 2 is a diagram showing an example of a schematic configuration of the control device 100 according to the first embodiment. The control device 100 is, for example, an information processing device such as a computer. The control device 100 has an external I / F (interface) unit 111, a display unit 112, an input unit 113, a storage unit 114, and a control unit 115. Note that the control device 100 may have various functional units that are included in known computers in addition to the functional units shown in Fig. 2.

[0019] The external I / F unit 111 is an interface for inputting and outputting information to and from other devices. For example, the external I / F unit 111 is an interface for controlling communications with other devices. One embodiment of the external I / F unit 111 is a network interface card such as a LAN card. For example, the external I / F unit 111 transmits and receives various data to and from the film forming processing system 10 and the irradiator 14 and measuring instrument 15 of the inspection device 1 via a network. The external I / F unit 111 may be, for example, an interface such as a USB (Universal Serial Bus) port. The external I / F unit 111 may be, for example, an interface such as a USB (Universal Serial Bus) port.

[0020] The display unit 112 is a display device that displays various types of information. Examples of the display unit 112 include a liquid crystal display (LCD) and a cathode ray tube (CRT). The display unit 112 displays various types of information. The input unit 113 is an input device that inputs various types of information, such as a mouse, a keyboard, or a touch panel. The input unit 113 accepts operation input from an operator or the like, and inputs operation information indicating the content of the accepted operation to the control unit 115.

[0021] The storage unit 114 is a storage device that stores various types of data. For example, the storage unit 114 is a storage device such as a hard disk, a solid state drive (SSD), or an optical disk. Note that the storage unit 114 may also be a semiconductor memory in which data can be rewritten, such as a random access memory (RAM), a flash memory, or a non-volatile static random access memory (NVSRAM).

[0022] The memory unit 114 stores an operating system (OS) and various programs executed by the control unit 115. For example, the memory unit 114 stores process condition data 120, which is a program containing commands (steps) for executing operations such as moving the irradiation range R and measuring the film thickness, and for executing the film formation process. The memory unit 114 also stores various data used by the programs executed by the control unit 115. In addition to the process condition data 120, the memory unit 114 also stores correlation data 121 and data set 122 (described below) used in film thickness measurement, for example. The memory unit 114 can also store other data in addition to the data exemplified above. The various programs and data may be stored in a computer-readable computer recording medium (e.g., a hard disk, an optical disk such as a DVD, a flexible disk, a semiconductor memory, etc.). The various programs and data may also be transmitted from other devices as needed and used online.

[0023] The control unit 115 is a device that controls the control device 100. Specifically, the control unit 115 is an electronic circuit such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), or an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 115 has an internal memory for storing programs and data, reads various programs stored in the storage unit 114, and executes the processes of the read programs. The control unit 115 functions as various processing units when the programs run. Specifically, the control unit 115 controls each unit of the film formation processing system 10 and includes a system control unit 131 that controls the film formation process, a measurement control unit 132 that controls spectroscopic measurement, and a measurement control unit 133 that controls film thickness measurement. Note that, in the first embodiment, the control unit 115 includes the system control unit 131 to the measurement control unit 133, but the functions of the system control unit 131 to the measurement control unit 133 may be distributed among multiple control units.

[0024] Before describing the film thickness measurement by the control device 100 in detail, a comparative film thickness measurement that differs from the film thickness measurement of this embodiment will be briefly described. To perform the comparative film thickness measurement, the coaxial probe 13 of the measurement device is first accurately positioned in the pattern region T1 where the film thickness is to be measured, and then the measurement is performed using the coaxial probe 13. The comparative coaxial probe 13 is positioned using, for example, image processing. In this case, an imaging unit such as a CCD (Charge Coupled Device) that acquires a surface image of the substrate W and a signal control unit that processes the image signal from the imaging unit are included. The signal processing unit is connected to the control device 100, which has an image processing program. The image processing program first identifies a reference point from the surface image of the substrate W, and then positions the irradiation area R at this reference point. Then, based on a preset movement distance from the reference point to the uneven pattern region T1, the coaxial probe 13 is moved to appropriately position the irradiation area R in one of the uneven pattern regions T1.

[0025] The positioning accuracy of this comparative embodiment depends on the accuracy of identifying the reference point, which is determined by, for example, the difference in brightness between only a small portion of the many pixels that make up the surface image. Therefore, ensuring the accuracy of identifying the reference point requires a high-resolution surface image. Even if the coaxial probe 13 placed at the reference point is positioned in the uneven pattern region T1, accurate film thickness measurement cannot be performed unless the irradiation range R is properly positioned within the uneven pattern region T1 using a movement mechanism based on a preset movement distance. Furthermore, to adequately measure the film thickness at each location in the uneven pattern region T1, the film thickness measurement data must be precisely synchronized with the measurement position of the movement mechanism that moves the irradiation range R. Furthermore, in the comparative embodiment of film thickness measurement, the confidentiality pattern of the substrate W is reflected in the acquired surface image, which can pose a problem in handling the surface image.

[0026] In contrast, in the film thickness measurement of the first embodiment, spectroscopic measurement is performed by irradiating the surface of the substrate W with a measurement light while moving it, acquiring a reflected light spectrum or absorbance spectrum at each position in the irradiation range R, and storing the data set 122. Then, the measurement control unit 133 performs measurement processing, as described below, on the stored data set 122 to measure the film thickness in the uneven pattern region T1. Therefore, the film thickness measurement of the first embodiment does not require the image processing device and the like required in the film thickness measurement of the comparative embodiment. Furthermore, there is no need to perform positioning operations for the irradiation range R, and no problems arise with handling surface images, allowing film thickness measurement to be performed using a simple method. Here, in this embodiment, in addition to the absorbance spectrum or reflectance spectrum, the intensity spectrum of reflected light from the irradiation range R or the absorbance intensity spectrum can also be used. In this disclosure, a spectrum that indicates the absorption or reflection characteristics for the wavelength of the measurement light irradiated on the irradiation range R is referred to as a "characteristic spectrum." The following explanation will be given of an example in which a reflectance spectrum is used.

[0027] The characteristics of the reflectance spectrum of reflected light used in the film thickness measurement of this embodiment will be described. As shown in Fig. 3A, in the film thickness measurement of the first embodiment, the reflectance spectrum of reflected light (Fig. 4) is measured while the irradiation range R is moved along the trajectory C as described above. In this measurement, reflectance spectra of various shapes are acquired depending on the position of the displaced irradiation range R. The reflectance spectrum represents the reflectance, which is the ratio between the intensity of the incident signal and the intensity of the reflected signal, for each wavelength. As will be described in detail later, the reflectance for each wavelength varies depending on the surface shape of the base layer 31 constituting each pattern arranged in the irradiation range R, the properties and film thickness of the surface film 33, etc.

[0028] On the other hand, if the configurations of the concave-convex pattern 32 and the flat pattern 34 are substantially the same in any position within the pattern regions T1 and T2, then if the irradiation range R is appropriately positioned at any position within the pattern regions T1 and T2, substantially the same reflected light spectrum will be obtained. Meanwhile, as described above, the areas of the irradiation ranges R are adjusted by vertically adjusting the positions of the measurement unit 11 and the coaxial probe 13 so that multiple (e.g., three or more) irradiation ranges R can be appropriately positioned within the pattern regions T1 and T2. As a result, substantially the same reflected light spectrum will be obtained between the irradiation ranges R obtained by irradiating the measurement light onto these common pattern regions T1 and T2.

[0029] FIG. 4 is a graph illustrating the reflectance spectra when the irradiation area R is appropriately positioned in the concave-convex pattern region T1 and the flat pattern region T2. ​​In the reflectance spectra (characteristic spectra) of the pattern regions T1 and T2, it can be seen that there are intersections where the same reflectance (value) is obtained at the same wavelength, i.e., wavelengths where there is almost no difference in reflectance between the reflectance spectra, whether measured in the concave-convex pattern region T1 or the flat pattern region T2. ​​Hereinafter, wavelengths where at least two reflectance spectra acquired at different positions in the mobile measurement intersect are referred to as "singular points." Meanwhile, the reflectance spectra of the concave-convex pattern region T1 and the flat pattern region T2 are generally different from each other, except for the two singular points P1.

[0030] It has been confirmed that at least one of these singular points P1, including singular points other than intersections (to be described later), appears in the reflectance spectra measured on substrates W having different shapes of the concave-convex pattern region T1 and different film properties and film thicknesses of the surface film 33. Furthermore, it has been found that this singular point has a correspondence relationship with the film thickness of the surface film 33 formed on the substrate W. Therefore, as will be described below, in this embodiment, singular points identified by measuring the reflectance spectra of at least two regions are used for film thickness measurement.

[0031] Suppose, for example, that a singular point is determined based on the intersection of reflectance spectra in a concave-convex pattern region T1 and a flat pattern region T2 within the surface of a certain substrate W. Even in this case, the reflectance value at the determined singular point may vary due to variations in the allowable film thickness between substrates W or within the surface of each substrate W, measurement errors, and the like. In such cases, for example, a preliminary experiment may be conducted to obtain multiple reflectance spectra for multiple substrates W and multiple regions T1 and T2 within these substrates W. Then, by calculating the reflectance at the previously determined singular point for these reflectance spectra, the range of reflectance variation can be determined in advance. From this perspective, the singular point can be defined as a wavelength at which the reflectance value in the reflectance spectrum falls within a predetermined range. As described below, this range can be, for example, within a range of approximately ±8% of the reflectance at the singular point determined based on the intersection of the predetermined reflectance spectra.

[0032] The significance of changes in the reflectance spectrum and singular points will be explained below. The measurement light, for example, contains light of multiple wavelengths. When the measurement light is generally reflected by the patterns 32 and 34 ( FIG. 3B ) below the surface film 33, the optical characteristics of the reflected light, such as the reflectance, change for each wavelength. In other words, it can be said that the reflectance spectrum changes depending on the shape of the patterns 32 and 34. Meanwhile, in the film formation process performed by the film formation system 10, the surface film 33 is formed to a generally uniform thickness on the upper end surfaces 32 a and 34 a of the patterns 32 and 34, which effectively reflect the measurement light. The reflected light from the reflection of the measurement light is also an interference wave, which reflects and interferes depending on the wavelength. The interference wave changes depending on the interference factor and the light absorption factor. Both the interference factor and the light absorption factor share common factors, such as the refractive index and film thickness, which are due to the film composition. Therefore, even if the spectral shape, etc. of the reflectance spectrum differs depending on the shapes of the patterns 32 and 34, if the composition and film thickness of the surface film 33 are roughly the same, it can be assumed that a singular point will appear in which the reflectance is the same at at least one wavelength.

[0033] Therefore, when spectroscopic measurement is performed while moving the irradiation position in the irradiation range R on such a surface film 33 of the same thickness, the shape of the reflectance spectrum changes according to the difference in the patterns 32, 34 depending on the irradiation position. Meanwhile, in these reflectance spectra with different shapes, a singular point appears where the reflectance is the same at a predetermined wavelength. Furthermore, it has been found that this singular point changes according to the thickness of the surface film 33 when the composition of the surface film 33 is the same.

[0034] To summarize the characteristics described above, the singular points of the surface film 33, which has a common composition, change depending on the film thickness. For example, FIG. 5 is a graph illustrating the change in the film thickness of a SiN film relative to the singular points. As illustrated in FIG. 5, the film thickness of the surface film 33 and the wavelength of the singular points are, for example, proportional to each other, and the wavelength of the singular points increases as the film thickness increases. As shown in FIG. 4, for example, one or more singular points appear, and therefore all correlations corresponding to these singular points may be identified, or at least one correlation may be identified.

[0035] On the other hand, depending on the shape of the patterns 32 and 34, they may not appear as intersections of the reflectance spectra, as in the example shown in Figure 6. In such cases, for example, when a reflective film is provided between the underlayer 31 and the surface film 33, or when the side surfaces of the uneven pattern 32 are tapered, it is estimated that the reflectance spectra will be higher overall depending on the measurement position, resulting in divergence between the reflectance spectra. When the reflectance spectra diverge, the wavelength at which the difference in reflectance between the reflectance spectra is smallest is considered to be the wavelength at which the reflectance between the reflectance spectra does not change significantly. The wavelength at which this difference in reflectance is smallest is then set as singularity point P2. As with singularities determined based on the intersections of the reflectance spectra, the range of reflectance for singularity point P2 determined using the above-described method can be determined in advance through preliminary experiments, taking into account film thickness changes, measurement errors, and other factors. Hereinafter, singularities P1 and P2 will sometimes be collectively referred to as singularity point P. As described above, in this embodiment, the film thickness of the concave-convex pattern region T1 is measured by utilizing the characteristics of the reflectance spectrum and the singular point.

[0036] Here, the correlation data 121 is obtained in advance, for example, by a preliminary test. The preliminary test determines the area of ​​the irradiation range R where the reflectance spectrum in the uneven pattern region T1 is approximately uniform, and the irradiation range R is adjusted to a similar size in film thickness measurement. In this example, the size of the irradiation range R is sufficiently smaller than the size of the uneven pattern region T1 and the size of the flat pattern region T2 surrounding the uneven pattern region T1. This allows the irradiation range R to be appropriately positioned in multiple positions in each pattern region T1 and T2. On the other hand, it may be impossible to appropriately position the irradiation range R for the relatively narrow uneven pattern region T3. If the reflectance spectrum is not uniform or stable when a portion of the uneven pattern region T3 is positioned in the irradiation range R, the pattern region T3 may be excluded from the circuit pattern formation area for determining the film thickness using spectroscopic measurement. However, if the size of the irradiation range R can be adjusted to include multiple irradiation ranges R in the uneven pattern region T3, the pattern region T3 may also be used to determine the film thickness.

[0037] Furthermore, as shown in FIGS. 4 and 6 , in the reflectance spectrum, in regions other than the singular point P, there are wavelengths where the reflectance value varies greatly depending on whether the irradiation area R is in the concave-convex pattern region T1 or the flat pattern region T2. ​​Therefore, by identifying the reflectance at that wavelength depending on the regions T1 and T2 where the spectroscopic measurement was performed, it is possible to identify which region T1 or T2 the reflectance spectrum was measured in, without imaging the surface of the substrate W with an imaging unit such as a CCD. If stable reflectance is obtained at multiple points in each pattern region T1 and T2, it can be determined that these reflectance spectra were obtained as a result of "the irradiation area R being properly positioned in the concave-convex pattern region T1 or the flat pattern region T2." This is because an improper positioning of the irradiation area R occurs, for example, when the irradiation area R is located at the boundary between the concave-convex pattern region T1 and the flat pattern region T2, making it difficult to obtain stable reflectance across multiple points in a wavelength region other than the singular point P.

[0038] Therefore, in this embodiment, a section in which the reflectance value at a predetermined wavelength falls within a predetermined allowable variation range between multiple positions is defined as an "effective measurement section." Then, based on the reflectance at a singular point P of the reflectance spectrum measured in this effective measurement section, the film thickness is determined from the above-mentioned correspondence relationship. An example of the predetermined wavelength is the wavelength (hereinafter also referred to as "measurement wavelength M1") at which the difference in reflectance is maximum between the characteristic spectra obtained in the concave-convex pattern region T1 and the flat pattern region T2. ​​Note that the measurement wavelength M1 does not necessarily have to be the wavelength at which the difference in reflectance is maximum in the reflectance spectrum of the actually measured substrate W. For example, the wavelength at which the difference in reflectance is maximum in the reflectance spectrum obtained in a preliminary test may be preset as the measurement wavelength M1.

[0039] Furthermore, as will be shown in the examples described later, almost no effect on the reflectance spectrum was observed when spectroscopic measurement was performed while moving the irradiation range R in a predetermined pattern such as a concave-convex pattern region T1 or a flat pattern region T2. ​​That is, it was confirmed that when spectroscopic measurement was performed on the same patterns 32 and 34, the obtained reflectance spectra were almost identical whether the irradiation range R was stationary or moved at a predetermined speed.

[0040] Returning to the explanation of the control device 100, correlation data between film thickness and singular points as shown in Fig. 5 is obtained in advance by a preliminary test or the like and stored in the storage unit 114 as correlation data 121. The correlation data 121 is calculated, for example, from the correspondence relationship between at least two singular points and film thickness. Similarly, the correspondence relationship between film thickness and singular points in the reflectance spectrum that changes depending on the type of concave-convex pattern 32 formed in the pattern regions T1 and T3 on other types of substrates W is stored in the storage unit 114 as correlation data 121.

[0041] The measurement control unit 132 controls spectroscopic measurement of the substrate W to calculate the reflectance spectrum of the substrate W. Specifically, it controls the irradiator 14 and the measuring instrument 15, irradiates the substrate W with measurement light from the irradiator 14, and detects reflected light from an irradiation range R, which is the irradiation area, with the measuring instrument 15. The measuring instrument 15 outputs data on the signal intensity of the detected light to the external I / F unit 111, and the measurement control unit 132 performs spectroscopic analysis such as Fourier transform on the signal intensity data to calculate the reflectance spectrum.

[0042] The reflectance can be determined by absolute reflectance, based on the amount of light irradiated onto the irradiation area R. Using absolute reflectance in film thickness measurement reduces the influence of irradiated light, which tends to have unstable signal strength, on the reflectance, enabling accurate film thickness measurement. In this case, the absolute reflectance is calibrated based on the absolute reflectance measured using a bare wafer having an underlayer 31 similar to the underlayer 31 of the substrate W for inspection. For example, calibration is performed so that the reflectance of a flat area on the bare wafer matches the absolute reflectance of a flat pattern area T2 on the substrate W for inspection, which does not have a surface film 33. Therefore, in the first embodiment, absolute reflectance is also used for the singular points in the correlation data 121, which indicates the correspondence between the singular points and film thickness. However, in the first embodiment, singular points identified from at least two reflectance spectra acquired while moving the irradiation position of the irradiation area R are used for film thickness measurement. Therefore, it is not necessary to calibrate the absolute reflectance based on the absolute reflectance measured using a bare wafer having an underlayer 31 similar to the underlayer 31 of the substrate W for inspection.

[0043] The measurement control unit 133 selects a measurement wavelength M1 (FIGS. 4 and 6) from a data set 122 of multiple reflectance spectra measured on a substrate W that is the target of film thickness measurement. The measurement control unit 133 then outputs the reflectance of the measurement wavelength M1 in each reflectance spectrum of the data set 122 in accordance with changes in the moving measurement position (FIG. 17A), and identifies an effective measurement section within the data set 122. Next, the measurement control unit 133 identifies, as a singular point, a wavelength at which the reflectance values ​​are the same or the difference between these reflectances is minimal in each reflectance spectrum in the effective measurement section identified from the data set 122. The measurement control unit 133 then identifies a film thickness corresponding to the singular point based on the correlation data 121. The identified film thickness may be displayed on the display unit 112, for example, or an alarm may be issued if the film thickness falls outside an allowable film thickness range.

[0044] An example of the operation of measuring the film thickness of the concave-convex pattern region T1 in the first embodiment will be described with reference to the flowchart in FIG. 7. First, a substrate W to be inspected, on which a surface film 33 is formed, is prepared (step S1). The substrate W is placed on the stage 21 by a transport mechanism such as a transport arm. Next, the movement mechanism of the inspection device 1 moves the collimator lens 12 and the coaxial probe 13 vertically and horizontally to set the size of the irradiation area R to a predetermined size, and positions the irradiation area R at the measurement start position. The measurement start position is, for example, an arbitrary position in the flat pattern region T2 surrounding the concave-convex pattern region T1 (the end position of the trajectory C1 indicated by the arrow in FIG. 3A). However, there are no particular limitations as long as the irradiation area R can be moved so that it passes over the concave-convex pattern region T1 and the flat pattern region T2. ​​The positioning of the irradiation area R at the measurement start position is performed in advance by determining the extent of the concave-convex pattern region T1 and the flat pattern region T2 using a magnifying glass or visually.

[0045] Next, the measurement unit 11 performs spectroscopic measurement at predetermined timings while moving the irradiation area R relative to the substrate W at a predetermined speed, for example, along a path C1, using the moving mechanism (step S2), and acquires a reflectance spectrum at each position on the path C1 (step S3, a process of acquiring a data set). The multiple characteristic spectra acquired during this movement of the light source are stored as a data set 122. The predetermined timing can be adjusted by the movement speed of the moving mechanism, the irradiation time of the measurement light, the irradiation interval, etc. The spectroscopic measurement timing can be determined as long as the irradiation area R is appropriately positioned in multiple different regions on the concave-convex pattern region T1 and the flat pattern region T2. ​​Preferably, the irradiation area R can be appropriately positioned in three or more different positions within each of the pattern regions T1 and T2. The multiple reflectance spectra acquired by this movement measurement are converted to absolute reflectances by the measurement control unit 132 and stored in the memory unit 114 as a data set 122.

[0046] The measurement control unit 133 identifies the reflectance at a predetermined measurement wavelength M1 for the reflectance spectrum of the reflectance spectrum of the data set 122, for example. Next, the measurement control unit 133 selects a reflectance spectrum within the effective measurement section from the data set 122 to be used to identify the singular point based on each reflectance at the measurement wavelength M1 (step S4: selecting a characteristic spectrum from the data set). The reflectance spectrum acquired in the effective measurement section is a reflectance spectrum of the same shape that is acquired consecutively, preferably three or more, during the mobile measurement process, while satisfying the condition that the reflectance value at the measurement wavelength M1 is within the allowable fluctuation range. As described above, the reflectance spectrum of such an effective measurement section can be identified as a reflectance spectrum that is estimated to have been measured when the irradiation range R is appropriately positioned continuously on one of the pattern areas (in this example, either pattern area T1 or T2). By using the reflectance spectrum of such an effective measurement section, the singular point can be accurately identified.

[0047] As shown in the graph of FIG. 17A in the example described below, the measurement control unit 133 first extracts the reflectance of the measurement wavelength M1 in each reflectance spectrum of the data set 122, for example, in the order of the measurement positions. FIG. 17A is a graph in which the horizontal axis represents the measurement position count and the vertical axis represents the reflectance of the measurement wavelength M1 in each reflectance spectrum of the data set 122. FIG. 17A also lists the reflectance of each singular point identified later, but these reflectances of the singular points are not essential for the film thickness measurement of the present disclosure and are listed for reference in this description. The measurement position count represents the number of measurements as a specific value, and the gap between the number of measurements corresponds to, for example, a time interval.

[0048] For each reflectance data point at measurement wavelength M1 as shown in FIG. 17A, reflectance spectra containing consecutive, preferably three or more consecutive, reflectances within the allowable fluctuation range are extracted as reflectance spectra of the effective measurement section. Reflectances within the allowable fluctuation range can be determined by calculating the difference in reflectance between two adjacent measurement positions and judging based on this difference. Specifically, for example, in a reflectance spectrum obtained in a preliminary test, the difference between the maximum and minimum reflectance values ​​at measurement wavelength M1 is referred to as the fluctuation range. If this difference is within ±15% of the reflectance fluctuation range, the reflectance spectra obtained at the two adjacent measurement positions are determined to be within the allowable fluctuation range at measurement wavelength M1 and to be included in the common effective measurement section. The reflectance difference between two adjacent measurement positions used to extract the effective measurement section as described above can also be considered as a differential value of the reflectance at measurement wavelength M1 in each reflectance spectrum, based on the measurement position.

[0049] The reflectance spectrum acquired during the period in which the irradiation range R is located in the effective measurement section identified in this way is selected as the reflectance spectrum for identifying the singular point, because, as described above, the reflectance spectrum of the effective measurement section is identified as having been measured in either the concave-convex pattern region T1 or the flat pattern region T2.

[0050] 17A and 17B are graphs in which the horizontal axis represents the count value of the number of spectroscopic measurements performed at a predetermined timing, and the vertical axis represents the reflectance value. In these graphs, the wavelength at the measurement wavelength M1 is plotted as an open circle, and the reflectance at the expected singular point that is assumed to be observed as the singular point P when a surface film 33 having the set film thickness (hereinafter sometimes referred to as the "set film thickness") is formed on the substrate W is plotted as a filled circle. In FIG. 17A, all of the reflectances at the expected singular points are within a preset range, and it can be determined that they are the same reflectance.

[0051] Here, when multiple reflectance spectra within each effective measurement section are extracted under three or more conditions, the measurement control unit 133 excludes the reflectance spectra at measurement positions located at both ends of the three or more consecutive reflectance spectra and selects only the reflectance spectrum at a measurement position located inside these ends (hereinafter also referred to as "intermediate spectrum VM"). This allows for the use of more stable reflectance spectra. Furthermore, if there are multiple intermediate spectra VM within each effective measurement section, the average value of the reflectance of these intermediate spectra VM may be calculated.

[0052] 7, the measurement control unit 133 extracts the average spectrum in each effective measurement section, and then identifies the reflectance at the wavelength of the singular point (expected singular point) in the intermediate spectrum VM in each effective measurement section (step S5). In this example, the identified wavelength is identified as the singular point of the reflectance spectrum obtained by performing spectroscopic measurement in the uneven pattern region T1 and the flat pattern region T2 as shown in FIG.

[0053] Next, the film thickness corresponding to the singular point is calculated (film thickness calculation process, step S6). In this example, it is determined whether the reflectance at the singular point (expected singular point) matches the reflectance at the singular point identified from the set film thickness of the surface film 33 based on the correlation data 121. Here, "the reflectance matches" includes a case where the reflectance is within a variation range (a preset range) of, for example, about ±8% with respect to the reflectance at the singular point. For example, if the reflectance at the singular point matches the reflectance of the set film thickness over the entire trajectory C1, it can be confirmed that the surface film 33 has a thickness that matches the set film thickness along the trajectory C1 where the spectroscopic measurement was performed. As described above, the film thickness measurement in the first embodiment allows the film thickness of the surface film 33 in the concave-convex pattern region T1 and the flat pattern region T2 to be calculated by a simple method.

[0054] On the other hand, if the thickness of the surface film 33 actually formed on the substrate W deviates from the set thickness, the predicted singular point and the actual singular point will not coincide. Therefore, for example, the reflectance measured at the predicted singular point will be different between the concave-convex pattern region T1 and the flat pattern region T2. ​​However, it is not necessary to confirm that the reflectance at the different predicted singular points in these regions T1 and T2 is measured. If it is confirmed that the reflectance at the predicted singular point in either region T1 or T2 deviates from the reflectance that should be measured at the set film thickness, it can be determined that the surface film 33 has a thickness different from the set film thickness. In this case, to determine the film thickness of the surface film 33 actually formed on the substrate W, the reflectance spectra shown in FIGS. 4 and 6 are compared between the concave-convex pattern region T1 and the flat pattern region T2 (e.g., by calculating the difference in reflectance across the entire wavelength range) to determine the actual singular point P. Then, based on the wavelength of this singular point, the actual film thickness can be determined from the correlation data 121.

[0055] (Variation) In the first embodiment, a substrate W having the simplest pattern arrangement, including pattern regions T1 and T2, has been described as an example. The film thickness measurement in the first embodiment can also be applied to substrates W including a wider variety of pattern regions, such as LSIs. Specifically, the film thickness of the surface film 33 on a stable pattern region, such as the concave-convex pattern region T1 on which a repetitive, regular concave-convex pattern 32 is formed, can be simply measured.

[0056] To perform the film thickness measurement of this example, a pattern region such as the flat pattern region T2 having a surface film 33 of the same film thickness is sufficient. However, it does not have to be flat like the flat pattern region T2, and it may be another concave-convex pattern region having a repeating regular concave-convex pattern different from the concave-convex pattern 32, as long as it is a region in which multiple irradiation ranges R can be appropriately arranged. Furthermore, in this example, the concave-convex pattern region T1 and the flat pattern region T2 are adjacent to each other on the substrate W, but this is not essential, and even if they are separated from each other, film thickness measurement in the concave-convex pattern region T1 can be performed without any problems using the film thickness measurement method of the present disclosure.

[0057] For example, in the case of an LSI substrate, when comparing the average spectra of each effective measurement section to identify a singular point, a reflectance spectrum other than that of the concave-convex pattern region T1 or the flat pattern region T2 may appear along the trajectory C1. Even in such a case, if the wavelength at which two different reflectance spectra intersect is significantly different from a pre-determined singular point (expected singular point), it can be determined that at least one of the reflectance spectra was not measured in the concave-convex pattern region T1 or the flat pattern region T2. ​​On the other hand, if the wavelength at which the two different reflectance spectra intersect is near the pre-determined singular point (within a pre-set wavelength range), it can be used to measure the film thickness as if it was measured in the concave-convex pattern region T1 or the flat pattern region T2.

[0058] Furthermore, by associating information about the measurement position with each reflectance spectrum in the data set 122 and combining this with the position information and movement speed information of the irradiation range R in the measurement control unit 132, it is also possible to identify the effective measurement section. Although the correlation data 121 illustrated in FIG. 5 is obtained by linearly approximating the correspondence between at least two singular points and film thickness, other methods may be used. For example, multiple sets of data between singular points and film thickness may be obtained under various conditions, including data with different properties of the underlayer 31 and the surface film 33, and data with different shapes and densities of the concave-convex pattern. Machine learning may then be performed using this data as learning data to construct model data. Film thickness measurements based on such data allow film thicknesses in a wide variety of pattern regions to be measured.

[0059] As described above, the reflectance at the singular point is an index showing the film thickness of the surface film 33, but there are cases where a disturbed reflectance different from the reflectance at the singular point is measured at, for example, only one or two points within the effective measurement section. In such cases, it is possible to suspect a film formation defect such as a void in the surface film 33 or a pattern defect in the underlayer 31. In such cases, as in the examples described below, the moving speed of the irradiation range R can be reduced and the measurement count per unit time increased, thereby increasing the resolution of the film thickness measurement and enabling precise inspection of film thickness defects.

[0060] Furthermore, according to the film thickness measurement of the present disclosure, it is possible to identify the approximate measurement position from, for example, information on the measurement timing associated with the data set 122 (for example, the count number set on the horizontal axis in FIGS. 17A and 17B), movement control information such as the movement speed of the movement mechanism of the inspection apparatus 1, and information on the timing of measurement light irradiation by the measurement control unit 132. Furthermore, in this example, an example has been described in which the irradiation range R is moved along an arbitrarily set trajectory C1 such as the trajectory C1 as shown in FIG. 3A, but this is not limiting. For example, the trajectory C1 of the irradiation range R may be set along a mesh that divides the surface of the substrate W into a grid pattern. Then, for example, by controlling the measurement light to be irradiated at the positions of the grid intersections, the surface of the substrate W can be measured in a grid pattern.

[0061] The movement mechanism of the inspection device 1 moves the collimator lens 12 and the coaxial probe 13 to move the irradiation range R along the trajectory C, but is not limited thereto. For example, the collimator lens 12 and the coaxial probe 13 may be fixed and the irradiation range R may be moved laterally by rotating or linearly moving the stage 21. The moving measurement used in the film thickness measurement of this example is not essential. The collimator lens 12 and the coaxial probe 13 may be moved along the trajectory C and stopped at the timing of measurement light irradiation, thereby alternately moving and stopping the light source. Furthermore, in this example, the measurement control unit 133 controls the spectroscopic measurement so that measurement light and reflected light are continuously irradiated and received to form mutually separated irradiation ranges R. However, this is not limited thereto. For example, the measurement light may be flashed at a predetermined time interval to form multiple separated irradiation ranges R.

[0062] The inspection device 1 of the first embodiment measures film thickness using either the absorbance spectrum or the reflectance spectrum as a characteristic spectrum, but the characteristic spectrum that can be used for film thickness measurement is not limited to this. For example, even if the intensity spectrum of reflected light or the absorbance intensity spectrum (FIG. 13) which is the difference between the intensity spectrum of irradiated light and the intensity spectrum of reflected light is used, a singular point similarly appears, so it can be treated in the same way as the reflectance spectrum, etc.

[0063] In this embodiment, it is preferable to provide an infrared absorbing sheet between the stage 21 and the substrate W to prevent noise from being mixed in from the stage 21. Alternatively, for example, the coaxial probe 13 may not have a coaxial structure, but may be provided as two separate probes, one connected to the irradiator 14 side and the other connected to the measuring instrument 15 side, and a through-hole may be formed vertically through the stage 21. The probe on the irradiator 14 side may be disposed below the through-hole in the stage, and the probe on the measuring instrument 15 side may be disposed above the through-hole, and the infrared light irradiated onto the substrate W may be received, thereby preventing noise from being mixed in from the stage 21. In this case, the irradiation range R can be moved relative to the substrate W by shifting the substrate W placed on the stage 21.

[0064] As such, the characteristic spectrum when the measurement light passes through the substrate W can be, for example, the intensity spectrum of the transmitted light that has passed through the substrate W and is received by the probe on the measuring instrument 15 side, or the absorbance intensity spectrum, absorbance spectrum, or transmittance spectrum, which are the differences between the intensity spectrum of the irradiated light and the intensity spectrum of the transmitted light and the intensity spectrum of the reflected light. Since the transmitted light is the difference between the light irradiated to the irradiation range R and the light reflected and absorbed by the substrate W, it can be said that the intensity spectrum and transmittance spectrum of the transmitted light measure characteristics corresponding to the reflection and absorption for the wavelength of the measurement light. Therefore, the intensity spectrum and transmittance spectrum of the transmitted light also correspond to the characteristic spectrum of the present disclosure.

[0065] (Film forming processing system 10) The following briefly describes the film forming processing system 10 in which the inspection apparatus 1 of this embodiment and its modified examples is installed. Fig. 8 is a plan view showing the film forming processing system 10. The film forming processing system 10 includes a loader module 61, a load lock module 65, a vacuum transfer module 66, and first to third processing modules 7A to 7C.

[0066] The loader module 61, the load lock module 65, and the vacuum transfer module 66 are arranged in this order in the front-to-rear direction.

[0067] The loader module 61 includes a housing whose interior is at atmospheric pressure, a transport mechanism 62 for substrates W provided in the housing, and four load ports 63, and the inspection apparatus 1 according to this embodiment is disposed in the housing. A transport container 64 called a FOUP (Front Opening Unified Pod) for storing substrates W is placed on each load port 63. The transport mechanism 62 includes, for example, an articulated arm that can move left and right, and is capable of transporting substrates W between the transport container 64 on each load port 63, each load lock module 65, and the inspection apparatus 1.

[0068] In this example, there are provided three load lock modules 65. Each load lock module 65 has a housing, and the housing is connected to the loader module 61 and the vacuum transfer module 66 via gate valves G provided at the front and rear of the housing, respectively.

[0069] Each load lock module 65 is configured so that the pressure inside the housing can be freely changed between atmospheric pressure and vacuum pressure when gate valves G at the front and rear of the housing are closed. A stage (not shown) is provided inside the housing, and the stage can carry a substrate W and transfer the substrate W to the transfer mechanism 62 and a vacuum transfer mechanism 67 (described later) that access the load lock module 65.

[0070] The vacuum transfer module 66 includes a housing 66a and a vacuum transfer mechanism 67 provided inside the housing 66a. The housing 66a is connected to an exhaust mechanism (not shown), such as a turbo molecular pump, via an exhaust pipe, and the inside is maintained in a vacuum atmosphere by exhaust by the exhaust mechanism.

[0071] The first to third process modules 7A to 7C are connected to a housing 66a of a vacuum transfer module 66 via a gate valve G1, and are arranged side by side on both the left and right sides of the housing 66a when viewed from the front. The transfer of the substrate W between the first to third process modules 7A to 7C and the load lock module 65 is performed by a vacuum transfer mechanism 67 including, for example, an articulated arm.

[0072] The diagram shows the correspondence between the processes performed in each of the first to third process modules 7A to 7C and the series of processes described above. The first process module 7A performs a COR process, which alters the oxide film formed on the surface of the base layer 31 of the substrate W to generate reaction products, and the second process module 7B performs a PHT process, which sublimates and removes the reaction products. The third process module 7C performs a film formation process, which forms a surface film 33. Each of the process modules 7A to 7C includes a process chamber 71 that is evacuated to create a vacuum atmosphere inside, and a mounting table 72 that is installed within the process chamber 71 and on which the substrate W is placed. Each process step is performed within the process chamber 71.

[0073] The system control unit 131 of the control device 100 outputs control signals to each part of the film forming processing system 10 according to each program stored in the storage unit 114, and controls the operation of each part. Specifically, the system control unit 131 controls the operation of the first to third processing modules 7A to 7C, the opening and closing of the gate valves G and G1, the transfer mechanism 62, the vacuum transfer mechanism 67, etc.

[0074] The transfer path of the substrate W in the film forming processing system 10 is first as follows: transfer container 64 → loader module 61 → load lock module 65 → vacuum transfer module 66 → first processing module 7A → vacuum transfer module 66 → second processing module 7B → vacuum transfer module 66 → third processing module 7C. During this transfer process, the oxide film on the surface of the base layer 31 of the substrate W is removed, and then a surface film 33 is formed on the substrate W. Next, the substrate W is transferred in the order of the third processing module 7C → vacuum transfer module 66 → load lock module 65 → loader module 61 → inspection device 1. The substrate W on which the surface film 33 has been formed during this transfer process undergoes film thickness measurement in the inspection device 1. If the result of the film thickness measurement falls within a predetermined allowable film thickness range, the substrate W is transferred to the transfer container 64, and then transferred together with the transfer container 64 to the next processing device by a transfer device (not shown). The substrate W whose film thickness measurement result is not within the allowable film thickness range and is determined to be defective is stored in a rejected substrate storage area (not shown) provided in the loader module 61, for example.

[0075] (deposition module) Next, the third process module 7C, which is a film formation module, will be described as a representative of the process modules 7A to 7C, using the vertical cross-sectional side view of Figure 9. The description will be centered on a case where film formation is performed as substrate processing. The third process module 7C is configured to be airtight, and the process vessel 71 is cylindrical. A mounting table 72 is provided within the process vessel 71.

[0076] The mounting table 72 is electrically grounded and made of a metal such as nickel. The mounting table 72 supports the substrate W placed on its upper surface horizontally. The lower surface of the mounting table 72 is electrically connected to a support member 73 made of a conductive material. The mounting table 72 is supported by the support member 73. The support member 73 is supported by the bottom surface of the processing vessel 71, and its lower end is electrically connected to the bottom surface of the processing vessel 71. Therefore, the processing vessel 71 is also grounded.

[0077] The mounting table 72 has a built-in heater 74, which can heat the substrate W mounted on the mounting table 72 to a predetermined temperature. The mounting table 72 is provided with lifter pins 75 for raising and lowering the substrate W. When loading the substrate W into the third processing module 7C, the lifter pins 75 are raised by an elevation mechanism (not shown) to receive the substrate W from the vacuum transfer mechanism 67 (FIG. 8), and after the vacuum transfer mechanism 67 leaves, the lifter pins 75 are lowered to place the substrate W on the mounting table 72.

[0078] A substantially disk-shaped showerhead 76 is provided on the inner surface of the processing vessel 71 above the mounting table 72. The showerhead 76 is supported on the upper part of the processing vessel 71 via an insulating member 71a such as ceramics. This electrically insulates the processing vessel 71 from the showerhead 76. The showerhead 76 is made of a conductive metal such as nickel.

[0079] The shower head 76 contains a gas diffusion space 76a, faces the mounting table 72 at its bottom, and is provided so as to close the interior of the processing vessel 71 from above. The shower head 76 has the gas diffusion space 76a formed therein and has a number of dispersed gas outlet holes 76c that open toward the mounting table 72. A gas supply path 77a is connected to the top of the shower head 76 to introduce various gases into the gas diffusion space 76a. A gas supply unit 77 is connected to the gas supply path 77a.

[0080] The gas supply unit 77 has gas supply lines connected to gas supply sources for various gases used in forming the surface film 33. Each gas supply line branches appropriately according to the film formation process and is provided with control devices for controlling the gas flow rate, such as valves such as on-off valves and flow rate controllers such as mass flow controllers. The gas supply unit 77 supplies a purge gas, a source gas, and a reactive gas to the gas supply path 77a. For example, when the surface film is a SiN film, the purge gas is an inert gas, the source gas is SiH4 (silane) gas, and the reactive gas is NH3 (ammonia) gas. These gases are diffused in the gas diffusion space 76a and discharged from each gas discharge hole 76c.

[0081] The space surrounded by the lower surface of the showerhead 76 and the upper surface of the mounting table 72 forms a processing space where a film formation process is performed. The showerhead 76 is paired with the mounting table 72 and functions as, for example, an electrode plate for forming capacitively coupled plasma (CCP) in the processing space. A high-frequency power supply 78 is connected to the showerhead 76 via a matching box 78a. When generating plasma in the processing space, the high-frequency power supply 78 supplies high-frequency power (RF power) in accordance with the supply of gas from the gas supply unit 77. This applies the high-frequency power to the gas supplied from the showerhead 76 to the processing space, generating plasma in the processing space.

[0082] An exhaust port connected to an exhaust pipe 79a is formed at the bottom of the processing vessel 71, and an exhaust device 79 having a vacuum pump and a pressure adjustment valve is connected to the exhaust pipe 79a. By the operation of the exhaust device 79, the inside of the processing vessel 71 is depressurized to a predetermined vacuum level.

[0083] Next, a flow of film formation on a substrate W by the third processing module 7C under the control of the system control unit 131, which controls film formation in the control device 100, will be briefly described. First, the substrate W is placed on the mounting table 72 by the vacuum transfer mechanism 67 of the film formation processing system 10. The substrate W loaded has the concave-convex pattern region T1 exposed on its surface, and no surface film 33 is formed thereon. When performing film formation on such a substrate W, the system control unit 131 controls the exhaust device 79 to reduce the pressure inside the processing vessel 71. The system control unit 131 controls the gas supply unit 77 to supply various gases used for film formation from the gas supply unit 77 and introduce the processing gas into the processing vessel 71 from the shower head 76. Then, the system control unit 131 controls the high-frequency power supply 78 to supply high-frequency power from the high-frequency power supply 78 to generate plasma in the processing space, and film formation is performed on the substrate W. In this manner, the surface film 33 is formed on the substrate W by the third processing module 7C. Then, the lifter pins 75 are protruded from the stage 72 , and the rear surface of the substrate W is supported by the lifter pins 75 to lift the substrate W from the stage 72 and carry it out by the vacuum transfer mechanism 67 .

[0084] (Second embodiment) An inspection device 1B according to the second embodiment will be described with reference to Figures 10 to 16. In these figures, structures similar to those of the first embodiment are assigned common reference numerals, and duplicate explanations will be omitted, with differences from the first embodiment being mainly described. Figure 10 is a structural diagram showing the inspection device 1B according to the second embodiment, and Figure 11 is an explanatory diagram showing the principle of spectroscopic measurement by a hyperspectral camera (hereinafter referred to as HSC) 11B that constitutes the inspection device 1B.

[0085] As shown in FIGS. 10 and 11 , the HSC 11B includes a lens 12, a spectroscope 17, and a camera 18. In the second embodiment, the HSC 11B is configured to perform spectroscopic measurement by arranging, for example, 900 optical elements side by side. That is, the HSC 11B has a long, narrow rectangular irradiation area RB formed by arranging a large number of the irradiation areas R in the inspection apparatus 1 described with reference to FIG. 1 side by side. The entire surface of the substrate W can be efficiently spectroscopically measured by scanning the substrate W while moving this irradiation area RB. Specifically, the HSC 11B introduces incident light from the long, narrow rectangular irradiation area RB, which has entered through the lens 12, into the spectroscope 17 via a horizontal slit (not shown) and is then dispersed, and the light is then received by an area sensor 19 provided in the camera 18.

[0086] As shown in FIG. 11 , the area sensor 19 has, for example, 900 optical elements arranged in a row in the x′ direction (horizontal direction) in the same manner as the previously described illumination range RB. These optical element rows are arranged in a vertical direction intersecting the previously described horizontal direction within the area illuminated with light dispersed by the spectroscope 17. With this configuration, the area sensor 19 receives dispersed light of each wavelength in a matrix form using optical elements arranged within an area of ​​vertical width (Y) in each of regions (illumination ranges R) obtained by dividing the horizontal width (X) of the illumination range RB into, for example, 900 regions. The HSC 11B configured in this way can generate the previously described characteristic spectrum based on the results of measuring the luminous intensity of light received by each light-receiving element for each wavelength at multiple positions (900 positions in this example) in the horizontal direction of the illumination range RB in a single scan. HSC11B scans the irradiation range RB while moving in a direction (e.g., the Y direction) that intersects the longitudinal direction of the irradiation range RB (corresponding to the aforementioned "horizontal direction"), and performs spectroscopic measurement every short period of time, thereby decomposing the surface of the substrate W into a high-density matrix and performing spectroscopic measurement.

[0087] The large number of reflectance spectra acquired by one scan has a data size of, for example, terabytes. Each reflectance spectrum acquired by this one scan is stored in the storage unit 114 as a data set 122, for example, in association with position information of the irradiation range RB and position information in the irradiation range RB (position information of the optical elements in the area sensor 19). The data set is then used by each part of the control unit 115 for each process of film thickness measurement. The above-mentioned operation of acquiring the large number of reflectance spectra in one scan and each process of film thickness measurement are repeated in subsequent scans.

[0088] Because the HSC 11B performs spectroscopic measurement simultaneously at each lateral position of the irradiation range RB during one scan, there is no change in illuminance due to different measurement times. Furthermore, since the illuminance is roughly the same at multiple adjacent positions in the X direction within the irradiation range RB during one scan, the illuminance of light incident on the optical elements at these corresponding positions can be said to be roughly the same. Furthermore, because the top surface of the substrate W can be scanned in a short time and spectroscopic measurement can be performed in a high-density matrix, it is considered that there is almost no difference in illuminance between multiple adjacent positions in the Y direction as well as the X direction. Therefore, for each region of the surface of the substrate W that is spectroscopically measured in a high-density matrix, where there is almost no difference in illuminance between multiple adjacent positions in the X and Y directions, it is not necessary to consider the effect of the illuminance difference of the light irradiated onto the substrate W on the reflectance spectrum.

[0089] FIG. 12 is a partial plan view showing the irradiation range RB where spectroscopic measurement is performed in the second embodiment. FIG. 13 is a graph illustrating characteristic spectra in the regions T1 and T2 shown in FIG. 12, with the vertical axis representing the absorption intensity spectrum, which is the difference between the intensity of the irradiated light and the intensity of the reflected light, among the various characteristic spectra described above. It is assumed that a surface film 33 of the same thickness is formed in the regions T1 to T3 shown in FIG. 12. In this example, scanning is performed while moving the irradiation range RB on the substrate W. However, the absorption intensity spectrum measured in the irradiation range RB at the position shown in FIG. 12 results in a number of absorption intensity spectra that are slightly shifted from each other at each measurement position in the width direction of the irradiation range RB. Therefore, when the absorption intensity spectra obtained by scanning the regions T1 and T2 with the irradiation range RB are superimposed, a group of characteristic spectra (a group of absorption intensity spectra) including a range of intensity (light amount) values ​​is obtained, rather than the single linear characteristic spectrum with no range in reflectance values ​​as shown in FIG. 4 (FIG. 13). However, even in a group of absorbance intensity spectra with different intensity values, the intensity values ​​converge to a single point at the wavelength where the spectra in regions T1 and T2 intersect, and the aforementioned singular points P7 and P8 appear. Note that even when other characteristic spectra are measured as described in the first embodiment, groups of characteristic spectra and singular points with a certain range are obtained.

[0090] Therefore, according to the spectroscopic measurement of the second embodiment, the positioning of the present disclosure can be performed in a similar manner to that of the first embodiment. For example, based on the flowchart described with reference to Fig. 7, it is assumed that the irradiation range RB is moved while scanning over the regions T1 and T2, and a reflectance spectrum is acquired in the same manner as in the first embodiment, to perform film thickness measurement. If the irradiation range RB shown in Fig. 12 is not moved but is instead positioned across the regions T1 and T2 to be measured in advance, and film thickness measurement is performed in a single scan, a large number of reflectance spectra (e.g., corresponding to 900 light receiving elements, i.e., 900 pixels) can be acquired in the measurement of step S2 of Fig. 7, as described above.

[0091] 7, the reflectance spectra constituting these multiple reflectance spectra are stored in the storage unit 114 as data set 122, as described above. Next, the measurement control unit 133 identifies the reflectance at measurement wavelength M1 for each reflectance spectrum in the acquired data set 122, and selects the reflectance within the effective measurement section from data set 122 based on each identified reflectance (step S4). To explain this process with reference to the graphs in FIGS. 17A and 17B described in the first embodiment, the measurement count number on the horizontal axis corresponds to 1 to 900, and these reflectances are measured simultaneously without any time interval at horizontally divided positions within the irradiation range RB.

[0092] Then, the measurement control unit 133 selects the intermediate spectrum VM within each effective measurement section in the same manner as in the first embodiment, identifies the reflectance at the wavelength at the singular point (expected singular point) (step S5), and calculates the film thickness corresponding to the singular point (step S6). As described above, according to the measurement of the second embodiment, the film thicknesses of the surface film 33 on the regions T1 and T2 where the irradiation range RB is provided can be measured in a single scan. According to the spectroscopic measurement of the second embodiment, the entire surface of the substrate W is scanned while moving the irradiation range RB in the above steps, whereby the film thickness of the surface film 33 can be measured and inspected at high-density matrix positions on the substrate W. In this case, the graphs of FIGS. 17A and 17B described above for a single scan are acquired for each scan position of the irradiation range RB.

[0093] The positions where the film thickness is measured and inspected are identified from each piece of position information associated with the data set 122. Each piece of position information can be identified, for example, from the arrangement position of the irradiation range RB where the reflectance spectrum of the film thickness measurement target is acquired, and the position of the pixel (optical element) within the irradiation range RB.

[0094] Furthermore, as will be described in detail in the examples below, according to the film thickness measurement according to the present disclosure, particularly the second embodiment, the identification of singular points, the reflectance spectrum, etc. are unlikely to be affected even by blurring due to focus deviation or changes in illuminance. Therefore, even when applied to in-line inspection incorporated into a processing module where focus deviation and changes in illuminance are expected frequently due to disturbances such as vibration generation and illuminance fluctuations, film thickness measurement can be performed with almost no effect from these disturbances.

[0095] An example of this disturbance, ie, illuminance fluctuation, will be described. Fig. 14 is a graph illustrating reflectance spectra obtained by arranging an irradiation range RB across two adjacent regions (e.g., regions T1 and T2 in Fig. 12) having the same film thickness but different patterns, and performing spectroscopic measurement under different illuminances L1 to L3. The solid line in Fig. 14 indicates a representative reflectance spectrum for one of regions T1 and T2, while the dashed line indicates a representative reflectance spectrum for the other region. As described above, in the spectroscopic measurement of the second embodiment, in a single scan of spectroscopic analysis, the illuminance can be considered to be approximately the same at multiple positions that are horizontally consecutive within the irradiation range RB. Therefore, the reflectance spectra of adjacent regions measured in a single scan indicate that the spectroscopic measurement was performed at approximately the same illuminance.

[0096] On the other hand, as scanning is repeated for multiple substrates W, the illuminance of the irradiated light may change due to, for example, contamination of the window through which the irradiated light and reflected light pass. In this regard, FIG. 14 shows that even when reflectance spectra are acquired under different illuminances L1 to L3, the wavelength of the singular point where the reflectance spectra acquired in regions T1 and T2, which have different pattern shapes, intersect remains unchanged. Therefore, according to the spectroscopic measurement of the second embodiment, even if illuminance fluctuations expected in inline inspection occur, the film thickness can be stably measured based on the wavelength of the singular point, which is less susceptible to such illuminance fluctuations. In the following modified example, an example of inline inspection using a film deposition module 7E equipped with an inspection device 1B will be described.

[0097] (Application example of the second embodiment) In an application example of the second embodiment, the inspection apparatus 1B is attached to a semi-batch type film formation module 7E (substrate processing apparatus) installed in place of the third processing module 7C where film formation processing is performed, and an in-line inspection is performed in the film formation module 7E immediately after film formation processing. FIGS. 15 and 16 are a longitudinal side view and a transverse plan view, respectively, of the semi-batch type film formation module 7E. As shown in these figures, the processing vessel 71B is, for example, a flat, cylindrical vacuum vessel, and a horizontal rotating table (table) 72B serving as a mounting table is provided therein. The rotating table 72B rotates around a central axis (rotation axis) M by a rotation mechanism 73B provided at the center thereof. A plurality of substrates W are placed on the rotating table 72B, and the substrates W are revolved around the central axis M as the rotating table 72B rotates.

[0098] 16, a source gas nozzle 51 for supplying a source gas and a reaction gas nozzle 52 for supplying a reaction gas are provided in a region through which the substrate W passes during revolution. Two regions between the source gas nozzle 51 and the reaction gas nozzle 52 are provided with purge gas nozzles 53 for supplying purge gas, respectively. The source gas, reaction gas, and purge gas nozzles 51, 52, and 53 are arranged circumferentially spaced apart from one another and extend horizontally from the sidewall of the processing vessel 71B toward the center of the processing vessel 71B. The source gas, reaction gas, and purge gas nozzles 51, 52, and 53 are provided with a number of gas discharge holes 50 (FIG. 15) along the longitudinal direction for discharging the supplied gases into the processing vessel 71B.

[0099] 16, by disposing partition members 56 in the two regions surrounded by the two purge gas nozzles 53, the space within the processing vessel 71B is partitioned into a region 54 to which a source gas is supplied and a region 55 to which a reactive gas is supplied. This prevents the source gas and the reactive gas from mixing within the processing vessel 71B. The region 54 to which the source gas is supplied and the region 55 to which the reactive gas is supplied are connected to an exhaust device 79 (FIG. 15) via exhaust paths 57 and 58 equipped with valves V1 and V2, respectively.

[0100] The gas supply unit 77 (process gas supply unit) is composed of supply paths independent of each other and includes source gas, reactive gas, and purge gas supply systems 77b, 77c, and 77d, each having its own gas supply source. The source gas, reactive gas, and purge gas supply systems 77b, 77c, and 77d are each provided with a flow rate controller such as a valve or a mass flow controller, and are connected to source gas, reactive gas, and purge gas nozzles 51, 52, and 53. As a result, the source gas, reactive gas, and purge gas nozzles 51 to 53 are continuously supplied with the source gas, reactive gas, and purge gas from their respective supply sources.

[0101] In this film formation module 7E, as the turntable 72B rotates, the substrate W passes through the source gas supply region 54, causing the source gas to be adsorbed onto the wafer surface. Next, as the substrate W passes through the reactive gas supply region 55, the source gas and the reactive gas on the wafer surface react to form a film. In this way, as the substrate W passes alternately through the source gas supply region 54 and the reactive gas supply region 55, a surface film 33 is formed on the substrate W by the ALD method, as in the first embodiment.

[0102] The processing vessel 71B has an opening at a portion above the region 55 to which the reaction gas is supplied, and the opening is closed by a window 76B that transmits light for the spectroscopic measurement described above. To maintain the airtightness of the processing vessel 71B, the periphery of the window 76B is sandwiched between the processing vessel 71B and a top lid 76C attached to the top of the processing vessel 71B via an O-ring. The top lid 76C is open above the central region of the window 76B that transmits light so as not to block the central region.

[0103] HSC 11B is disposed above window 76B and configured to receive light reflected from irradiation area RB through a central region of window 76B. HSC 11B is installed with lens 12 facing so that irradiation area RB is positioned within a range that encompasses the diameter of the revolving substrate W (FIG. 25). Similarly to each of nozzles 51-53, the orientation of lens 12 of HSC 11B is adjusted so that irradiation area RB extends radially from the sidewall of processing vessel 71B toward the center of processing vessel 71B, i.e., toward central axis M, in a plan view.

[0104] After the surface film 33 is formed, each substrate W is scanned by the HSC 11B while revolving within the film-forming module 7E. That is, after each revolving substrate W enters the region below the irradiation range RB, its entire surface passes below the irradiation range RB. The HSC 11B performs spectroscopic measurements of the moving irradiation range RB at short intervals, thereby measuring the reflectance spectrum of the entire upper surface of the substrate W. Such in-line inspection in the film-forming module 7E allows film thickness measurements to be performed efficiently and accurately.

[0105] Here, in the past, it was considered difficult to use high-precision spectroscopic measurement such as the HSC11B for in-line inspection of the deposition module 7E due to the influence of various disturbances. Examples of disturbances include changes in illuminance over time due to fogging of the window 76B caused by various gases supplied during the deposition process, which can lead to poor diagnosis due to blurred images. Other disturbances include tilting of the turntable 72B from the center toward the outside and defocusing caused by rotational vibration of the turntable 72B. It was considered difficult to obtain accurate measurement results using conventional spectroscopic measurement using the HRC11B in such disturbance-prone environments. In contrast, film thickness measurement using the reflectance spectrum and its singular points as disclosed herein can be performed accurately and efficiently without being affected by disturbances, as will be described in the examples below.

[0106] (Other variations) The HSC 11B of the second embodiment is not limited to one that scans the linear irradiation range RB at short intervals while moving. For example, the HSC 11B may be another type of HSC, such as one that performs spectroscopic measurement by changing multiple spectral filters corresponding to different bands while keeping the area-shaped irradiation range RB fixed. Alternatively, instead of the HSC 11B, multiple measurement units 11 like those in the first embodiment may be prepared, and the coaxial probes 13 of each may be moved integrally, so that each irradiation range R moves integrally like the irradiation range RB while performing spectroscopic measurement at the same time.

[0107] Furthermore, the inspection device 1B is not limited to being attached to the film formation module 7E, but may be attached to another processing module, or may be disposed in the film formation processing system 10 as a stand-alone inspection device as shown in the first embodiment without being attached to a processing module. In this case, the inspection device 1B is not limited to being attached to a rotary stage, but may be placed on a rail-like stage that moves in one direction and spectroscopic measurement may be performed while moving the substrate, or the irradiation range RB may be moved relatively by moving the HSC 11B while the substrate is stationary. [Example]

[0108] Example 1 To verify the effectiveness of film thickness measurement by moving measurement, moving measurements were performed in which the placement of the irradiation range R in the pattern area T1 was different from each other, and the resulting differences were confirmed. In order to confirm whether the method is effective even when the irradiation range R is moved arbitrarily over the concave-convex pattern areas T1 and T2, the measurements were performed under the following conditions. A. Experimental conditions Film thickness measurement was performed on a substrate W having the pattern arrangement of pattern regions T1 and T2 exemplified in the first embodiment. The movement measurement was performed by placing the substrate W on a stage that can rotate around its center, and moving the irradiation range R so as to revolve over the outer concave-convex pattern region T1 around the centrally located concave-convex pattern region T1. As a result, the irradiation range R was moved so as to revolve approximately 160 degrees over the outer concave-convex pattern region T1 and flat pattern region T2 around the central pattern region T1.

[0109] Then, different conditions for the mobile measurement were set as Example 1-1, in which the measurement positions were relatively dense, and Example 1-2, in which the measurement positions were relatively sparse, and set data for reflectance spectra were acquired for each. In Example 1-1, the irradiation time of the measurement light was set so that the movement speed of the irradiation range R was 11 mm / sec and the movement distance of the irradiation range R per irradiation was 1.1 mm. In Example 1-2, the movement speed of the irradiation range R was set to a relatively slow 1.24 mm / sec, and the movement distance was set to a relatively short 0.12 mm. Changes in the measurement wavelength M1 and the reflectance of the expected singular point relative to the measurement position count for each reflectance spectrum acquired in Examples 1-1 and 1-2 were confirmed.

[0110] Furthermore, spectroscopic measurements were performed in a stationary state to obtain data sets, and the difference in reflectance at the predicted singular points between the mobile measurements and the stationary measurements was confirmed as Example 1-3. In Example 1-3, the reflectance at the predicted singular points of each reflectance spectrum was confirmed for each data set obtained by mobile measurement under the mobile measurement conditions of Examples 1-1 and 1-2, and for data obtained by a single measurement in a stationary state.

[0111] B. Experimental Results 17A and 17B show portions of graphs showing the reflectance at a predetermined wavelength and the measurement position count for each reflectance spectrum of Examples 1-1 and 1-2. In FIG. 17B, plots that were densely overlapping in the original data have been thinned out to clarify the plots. Similar thinning is also performed for FIGS. 18, 21A, and 21B, which will be described later. For Example 1-1 shown in FIG. 17A, as described in this embodiment, all reflectances at the predicted singular points were within the variation range, and no errors due to the orientation of the irradiation range R or errors due to moving measurements were confirmed. Furthermore, three locations within the allowable variation range for the reflectance at each measurement wavelength were also observed, which demonstrated that it was sufficient to identify singular points and measure film thicknesses.

[0112] 17B, ​​the measurement positions were relatively densely spaced, so the reflectance versus measurement count was plotted finely, indicating that the moving measurements were performed in a narrow and dense manner. Furthermore, the number of plots for the reflectance at each measurement wavelength was also increased, confirming that there were more effective measurement sections than in Example 1-1.

[0113] It was found that the reflectances of the predicted singular points were all within the variation range except for one measurement position. It is believed that the singular points differ in the reflectance spectrum of that one position. Furthermore, the measurement wavelengths and the reflectances of the predicted singular points before and after that one position are roughly the same, so it is believed that they are the same reflectance spectrum and the same pattern area. Therefore, it is suspected that the one measurement position has a poor film thickness or foreign matter contamination. By measuring at relatively dense measurement positions as in Example 1-2, it is possible to detect minor abnormalities within the pattern area.

[0114] FIG. 18 shows the experimental results of Examples 1-3, showing the reflectance of the predicted singular points of each reflectance spectrum of each data set together with the measurement position count. This indicates that the fluctuation range of the reflectance values ​​of the predicted singular points of each reflectance spectrum of data sets under different moving measurement conditions was similar and was not different from the reflectance of the predicted singular points of the reflectance spectrum when stationary. In other words, it was considered that each reflectance spectrum was not affected by differences in the moving speed or moving distance of the irradiation range R. In Examples 1-1 to 1-3, the pattern orientation within the irradiation range R was changed by up to 160 degrees, but no tendency for the reflectance to fluctuate was observed. Therefore, it was found that spectroscopic measurement in a pattern area where a surface film of the same thickness is provided is not affected by the pattern orientation within the irradiation range R, and the same reflectance spectrum can be obtained as long as the pattern density within the irradiation range R is approximately the same. As described above, it was found that even with arbitrary moving measurements involving rotation of the irradiation range R, no tendency for the reflectance to fluctuate was observed, and film thickness measurement was possible.

[0115] Our findings from the above are shown in Figures 19A and 19B. Figures 19A and 19B show the irradiation range R resulting from changes in the mobile measurement conditions and the uneven pattern placed within the irradiation range R. The protrusions shown on the irradiation range R in each figure indicate the intensity distribution of the measurement light. Figure 19A shows the case where the movement distance of the irradiation range R is zero in a stationary measurement, and Figure 19B shows the case where the movement distance of the irradiation range R is relatively long in a mobile measurement.

[0116] Compared to the irradiation range R in FIG. 19A, the irradiation range R in FIG. 19B is longer by the distance moved in the direction of movement of the irradiation range R. Therefore, within the irradiation range R, the number of convex portions, for example, of the concave-convex pattern of the pattern area is increased by the amount of extension of the irradiation range R. However, because the concave-convex pattern of the concave-convex pattern area T1 is provided in a repeated and regular pattern, the concave-convex pattern is similarly arranged even in the extended part of the irradiation range R, and the density of the concave-convex pattern throughout the irradiation range R is the same even when compared to the irradiation range R in static measurement. For this reason, it was inferred that film thickness measurement in such a regular pattern area can be performed with high accuracy without being affected by differences in the conditions for static measurement and moving measurement.

[0117] Example 2 The effectiveness of the film thickness measurement method disclosed herein was verified by measuring the reflectance spectra of surface films of different film thicknesses while moving the film across the film to check the extent to which differences due to the reflectance of the predicted singular points appeared.

[0118] A. Experimental conditions FIG. 20 is a plan view showing the spectroscopic measurement of Example 2. Four wafers with the same base layer were prepared: three TEG wafers W1–W3 with uniform and regular test patterns formed on the base layer, and one bare wafer B1 with no pattern. The test patterns of the TEG wafers W1–W3 were formed only in the central region Wa of the surface, with the surrounding area being a flat region without a pattern. SiN films with thicknesses of 0 nm, 6 nm, and 15 nm were formed on the entire surfaces of the three TEG wafers W1, W2, and W3, respectively. These three TEG wafers W1–W3 and the bare wafer B1 were aligned around the center of rotation of a rotating stage, and moving measurements were performed by passing these substrates through the irradiation range R on approximately the same trajectory. This allowed moving measurements across the TEG wafers W1–W3 and the bare wafer B1 to acquire data sets of reflectance spectra. The reason why the bare wafer B1 was subjected to spectroscopic measurement is that the reflectance spectrum of the bare wafer B1 is used to convert the reflectance spectrum of each of the TEG wafers W1 to W3 into an absolute reflectance.

[0119] B. Experimental Results 21A and 21B are graphs showing the experimental results of Example 2. FIG. 21A shows the reflectance and measurement position count of the predicted singular point in each reflectance spectrum of the data set, where the predicted singular point corresponds to a SiN film thickness of 6 nm. As shown in the figure, for the 6-nm-thick TEG wafer W2, the reflectance of the central region Wa and the reflectance of the flat region are approximately equal. Thus, when the predicted singular point corresponds to a film thickness, the reflectance of the predicted singular point is the same even if the pattern shapes are different, confirming that the predicted singular point is a singular point. Furthermore, if there are two pattern regions with different patterns, the singular point can be identified by extracting the same wavelength that results in the same reflectance in the reflectance spectrum of each region, and it was confirmed that this can be measured using the film thickness measurement method disclosed herein.

[0120] For the TEG wafers W1 and W3, the reflectance of the central region Wa differed from the reflectance of the flat region, which confirmed that the predicted singular points were not singular points for the TEG wafers W1 and W3.

[0121] Figure 21B shows the reflectance and measurement position count of the predicted singular points in each reflectance spectrum, similar to Figure 21A, corresponding to a SiN film thickness of 15 nm. As can be seen from the figure, the reflectance of the central region Wa was approximately equal to the reflectance of the flat region for the 15 nm-thick TEG wafer W3. On the other hand, the reflectance of the central region Wa differed from the reflectance of the flat region for the 0 nm and 6 nm-thick TEG wafers W1 and W2. As described above, by acquiring predicted singular points and comparing the reflectances as disclosed herein, it was possible to clearly identify pattern regions where surface films of the same thickness are formed, and it was also possible to grasp the pattern region. Furthermore, it was confirmed that the predicted singular points could be found by identifying the reflectance spectra of each effective measurement section, and that the thickness of the surface film could be accurately measured.

[0122] Example 3 Under conditions where the focus deviation and illuminance difference expected in the in-line inspection described above occur, the trends of the singular points and reflectance spectrum identified by the spectroscopic measurement of the second embodiment were confirmed.

[0123] A. Experimental conditions A bare wafer with multiple sets of test patterns on its surface was prepared as the substrate W to be used in the experiment. Each set of test patterns had two different pattern areas, on which a SiN film of the same thickness was formed, in order to identify singular points for each set. The film thicknesses of the different sets were then set to different values ​​in order to identify singular points corresponding to the film thickness. The entire top surface of the substrate W was then scanned, and the two pattern areas of each set of test patterns were spectroscopically measured. Reflectance spectra of the two different pattern areas for each set of test patterns were obtained, and the singular points corresponding to the film thickness of each set of test patterns were identified from the intersections of these spectra.

[0124] In order to reproduce an environment with focus deviation and illuminance differences, spectroscopic measurements were performed at low resolution, where the height of the lens 12 was adjusted to make the width of the irradiation area RB on the substrate W relatively large, and at high resolution, where the width was made relatively small and the resolution was approximately 110 times finer than the low resolution. The high resolution reproduced a state where the illuminance was relatively high and in focus, while the low resolution reproduced a state where the illuminance was relatively low and out of focus.

[0125] In addition, for the reflectance spectra of each data set acquired by the high- and low-resolution scans, data sets converted to absolute reflectance were also prepared in order to cancel the illumination difference. <1> ~ <5> This is a table summarizing each condition <1> ~ <5> Prepare a data set for each condition and <1> ~ <5> Figure 22 shows the trend of the singular points identified in the test pattern. <1> ~ <4> The wavelengths of the singular points measured under the conditions are also shown. <5> is obtained by spectroscopic measurement in the first embodiment using a single irradiation range R.

[0126] And each condition <1> ~ <5> It was confirmed whether the singular point wavelengths identified by the measurement of each set of test patterns in the previous section corresponded to the film thickness of each set of test patterns. As an additional test, the singular points in test patterns with relatively large voids were also confirmed by low-resolution spectroscopic measurement.

[0127] B. Experimental Results 23 is a graph showing the wavelength of the singular point showing the results of Example 3. In this figure, the singular point wavelength of each set of test patterns is plotted for each of the above conditions, with the horizontal axis representing the condition. <1> The vertical axis shows the singular wavelength [nm] of the reflectance spectrum without absolute value conversion. <2> ~ <5> The singular wavelength [nm] of the reflectance spectrum is taken. <1> For each set of test patterns obtained in the singular wavelength (vertical axis), the same set of test patterns is used under each condition. <2> ~ <5> The singularity wavelength (horizontal axis) measured by the method is plotted.

[0128] As shown in Figure 23, the condition <1> Each singular wavelength and the condition <2> ~ <4> The plots of the singular wavelengths of and overlap on a line with a slope of 1. As can be seen from these plots, <1> ~ <4> It was confirmed that the wavelengths of the singular points measured in the second embodiment are identical and do not differ depending on the film thickness of each test pattern, regardless of whether the wavelengths are low or high resolution or whether they are converted to absolute reflectance. Therefore, it was confirmed that the spectroscopic measurement of the second embodiment allows film thickness measurement and the like to be performed based on the reflectance spectrum utilizing the singular points of the present disclosure, without being affected by fluctuations in the focal length of the lens 12 or illuminance. It was also confirmed that the singular points can be accurately identified from the reflectance spectra of the relative values ​​measured as they are, without converting to absolute reflectance values ​​to cancel out differences in illuminance.

[0129] And, the conditions shown in Figure 23 <1> ~ <4> It was confirmed that the wavelength of each singular point in the condition coincides with the wavelength of the singular point corresponding to each film thickness. <3> ~ <5> The figure shows the relationship between the specific wavelengths and the film thickness. <3> , <4> As described above in the first embodiment, the wavelength of the specific point measured by the spectroscopic measurement is proportional to the film thickness, and it was confirmed that there is a corresponding relationship between the film thickness and the specific point in the spectroscopic measurement according to the second embodiment as well.

[0130] 23 and 24, the spectroscopic measurement conditions of the first embodiment are as follows: a singular point appears in the pattern area where the film thickness is 0 nm, i.e., where no SiN film is provided; however, the wavelength of the singular point is not proportional to the film thickness, as seen in the other singular point wavelengths for film thicknesses of 0 nm or more. <5> The singular wavelengths are determined under the conditions of the spectroscopic measurement of the second embodiment, including the film thickness of 0 nm. <1> ~ <4> The wavelengths were approximately 5 nm shorter than the respective singular wavelengths of the <5> This is thought to be due to a deviation specific to the calibration of the spectrometer used in the first embodiment. Therefore, it was inferred that if this deviation is identified and corrected in advance, the spectroscopic measurement of the first embodiment will have the same level of accuracy as that of the second embodiment.

[0131] Furthermore, Figure 24 shows the results of additional testing, showing singular points identified by the spectroscopic measurement of the second embodiment for another test pattern in which a SiN film containing voids was formed. Singular points appeared at wavelengths outside the singular point wavelength corresponding to the film thickness. Thus, it was confirmed that accurate singular points appeared and SiN films containing voids could be identified even with the low-resolution spectroscopic measurement of the second embodiment. Furthermore, it was inferred that low-resolution spectroscopic measurement, which can measure a wide range in one scan, makes it easier to find the reflectance spectra of different pattern areas within one scan, allowing for rapid identification of singular points. It was also inferred that spectroscopic measurement can be performed quickly in a high-density matrix on the substrate W, enabling efficient spectroscopic measurement.

[0132] Example 4 When film thickness measurement is performed using spectroscopic measurement by the HSC 11B in the film formation module 7E shown in the modified example of the second embodiment, it is confirmed whether positions on the substrate W can be detected for a large number of reflectance spectra included in each data set.

[0133] A. Experimental conditions 25 is a top perspective view of multiple substrates W that are the targets of spectroscopic measurement in Example 4. In Example 4, spectroscopic measurement was reproduced for multiple substrates W that were placed on a turntable 72B and revolved within a film formation module 7E, as shown in the modified example of the second embodiment. The position of the lens 12 was set under low-resolution conditions so that the width (X) of the irradiation range RB was longer than the diameter of the substrates W. Then, spectroscopic measurement was performed every short period of time while the irradiation range RB, which was positioned in a state extending in the direction toward the central axis M, was revolved relative to the multiple substrates W, and a large number of data sets were obtained.

[0134] B. Experimental Results 26 and 27 are graphs showing the experimental results of Example 4. FIG. 26 shows the intensity profile of one wavelength acquired at each position in the irradiation range RB at time t1. The intensity range inside the two dashed lines in FIG. 26 is the intensity range used for positioning and film thickness inspection in the present disclosure. Reflected light with an intensity falling within this intensity range can be determined to have been reflected on the substrate W and then incident on the HSC 11B, while reflected light with an intensity weaker than this intensity range is considered to have been reflected outside the substrate W, for example, on the turntable 72B. It can be seen that the boundary positions of these reflected lights with different intensities correspond to the black dot A and white dot B on the periphery of the substrate W shown in FIG. 25.

[0135] FIG. 27 is a graph showing the time-dependent change in the positions of points A and B in the irradiation range RB, which were identified using the correspondence between position and intensity in the irradiation range RB as shown in FIG. 26. Times t0 to t5 in the graph correspond to times t0 to t5 shown in FIG. 25. As shown in FIG. 27, the intersecting positions of the solid and dashed lines indicating the positions of points A and B represent the initial or final entry positions of the substrate W below the irradiation range RB. Points A and B gradually move away from this entry position, and at time t2, when points A and B are furthest apart, the diameter of the substrate W is considered to be located below the irradiation range RB. After time t2, points A and B gradually approach each other and become the same position. The period during which points A and B are not detected is the period until the next substrate W arrives within the irradiation range RB. The period during which point A moves from the inside to the outside near time t5 is the period during which the irradiation range RB moves along the notch.

[0136] 27, by determining the positions of points A and B in the irradiation range RB, it is possible to identify the position on the substrate W of the irradiation range RB that relatively revolves from the time and the change in the measurement range in the irradiation range RB from minimum width (initial entry position) → maximum width (substrate diameter position) → minimum width (final entry position). The position in the irradiation range RB at which a certain acquired reflectance spectrum was measured can be determined by comparing the data with data indicating the peripheral position of the substrate W as shown in FIG. 26. As described above, in-line inspection as shown in the modified example of the second embodiment allows the measurement position of a certain reflectance spectrum acquired in film thickness measurement to be identified.

[0137] As shown in FIG. 25 , the relative movement speed of the irradiation range RB relative to the substrate W is smaller inside the irradiation range RB and larger outside it, and the displacement directions at these positions are not strictly parallel. Therefore, differences in the amount and direction of movement inside and outside the irradiation range RB may affect the reflectance spectrum at each position, potentially resulting in errors in the positioning using the singular points of the present disclosure. To address this issue, a separate test pattern was moved irregularly on the revolving or rectilinearly moving substrate W, and spectroscopic measurements in the second embodiment were performed under various conditions, such as low resolution, high resolution, and with or without absolute value conversion, as shown in Example 4, to confirm the trends of singular points and other characteristics. In this experiment, as in Example 4, singular points corresponding to film thickness were identified from the reflectance spectrum measured for the test pattern. This also confirms that accurate positioning and other characteristics can be achieved without errors even in in-line inspection such as the modified example of the second embodiment.

[0138] It should be noted that the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects, and various omissions, substitutions, modifications, and combinations may be made to the above-described embodiments without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0139] C, C1, C2 orbit M1 measurement wavelength P1 singularity VM mid-spectrum W substrate 121 Correlation Data 122 datasets 33 Surface film

Claims

1. A method for measuring a film thickness of a substrate, comprising: a step of moving a light source relative to a substrate on which a film has been formed while irradiating the substrate with light, and acquiring a data set of characteristic spectra that indicate reflection or absorption characteristics at a plurality of positions on a trajectory of the light irradiated onto the substrate; selecting, from the data set, the characteristic spectrum acquired in an effective measurement section, which is a section in which the value of the characteristic spectrum at a predetermined wavelength falls within a predetermined allowable variation range between a plurality of positions on the trajectory; and when the characteristic spectrum is acquired at different positions within the surface of the substrate, a wavelength whose value in the characteristic spectrum is within a predetermined range regardless of the position of the light irradiation is called a singular point, determining the film thickness of the film formed on the substrate from the value at the singular point of the selected characteristic spectrum based on a previously determined correspondence between the singular point and the film thickness.

2. The method of claim 1 , wherein the characteristic spectrum is one of a reflected light intensity spectrum, an absorbance intensity spectrum, an absorbance spectrum, and a reflectance spectrum from the substrate.

3. 2. The method according to claim 1, wherein an area of ​​light irradiated from the light source onto the substrate is less than half the area of ​​a circuit pattern forming area on the substrate and less than half the area of ​​a flat area on which the circuit pattern is not formed.

4. The method according to claim 1 , wherein the predetermined wavelength is a wavelength at which a difference in value between a plurality of types of characteristic spectra obtained in areas of the surface of the substrate with different structures is greatest.

5. The method according to claim 1, wherein whether the characteristic spectrum has been acquired in the effective measurement section is determined based on a difference value between values ​​at the predetermined wavelength between two adjacent measurement positions on the trajectory.

6. 6. The method according to claim 5, wherein, when a difference between a maximum value and a minimum value of the characteristic spectrum at the preset wavelength is called a variation range, if the difference value is within ±15% of the variation range, the two adjacent measurement positions are determined to be included in a common effective measurement section.

7. 2. The method according to claim 1, wherein the singular point is the wavelength of the light at a position where multiple types of characteristic spectra obtained in areas of the surface of the substrate with different structures intersect, or, when the multiple types of characteristic spectra do not intersect, the wavelength of the light at a position where a difference between values ​​of the multiple types of characteristic spectra is minimum.

8. The method of claim 1 , wherein the step of acquiring the data set comprises acquiring the characteristic spectrum during a period in which the light source is moving.

9. The method of claim 1 , wherein the step of acquiring the data set comprises alternating between moving and stopping the light source, and acquiring the characteristic spectrum during periods when the light source is stopped.

10. The method of claim 1 , wherein the characteristic spectrum is acquired with a hyperspectral camera.

11. The method according to claim 10, wherein the illumination range of the hyperspectral camera is set to an elongated rectangular shape whose longitudinal dimension is greater than the diameter of the substrate, and the measurement using the hyperspectral camera scans the entire surface of the substrate by moving the illumination range relative to a plurality of the substrates placed on a stage in a fixed direction.

12. An apparatus for measuring the thickness of a film formed on a substrate, The stage and an inspection unit that includes a light source that irradiates light onto the substrate placed on the stage and receives reflected light; A control unit; Equipped with the control unit moves the light source relatively to the substrate on which the film is formed while irradiating the light, and acquires a data set of characteristic spectra that indicate reflection or absorption characteristics at a plurality of positions on a trajectory of the light irradiated onto the substrate; selecting, from the data set, the characteristic spectrum acquired in an effective measurement section, which is a section in which a value at a predetermined wavelength of the characteristic spectrum is within a predetermined allowable variation range between a plurality of positions on the trajectory; and when the characteristic spectrum is acquired at different positions within the surface of the substrate, a wavelength whose value in the characteristic spectrum is within a predetermined variation range regardless of the position of the light irradiation is called a singular point, calculating the film thickness of the film formed on the substrate from the value at the singular point of the selected characteristic spectrum based on a previously determined correspondence between the singular point and the film thickness.

13. The apparatus of claim 12 , wherein the characteristic spectrum is one of an intensity spectrum of reflected light from the substrate, an absorbance intensity spectrum, an absorbance spectrum, and a reflectance spectrum.

14. The apparatus according to claim 12, wherein an area of ​​light irradiated from the light source onto the substrate is less than half an area of ​​a circuit pattern forming area on the substrate and less than half an area of ​​a flat area on which the circuit pattern is not formed.

15. The apparatus according to claim 12 , wherein the predetermined wavelength is a wavelength at which a difference in value between a plurality of types of characteristic spectra obtained in areas of the surface of the substrate with different structures is greatest.

16. The device according to claim 12, wherein whether the characteristic spectrum has been acquired in the effective measurement section is determined based on a difference in values ​​at the preset wavelength between two adjacent measurement positions on the trajectory.

17. 17. The device according to claim 16, wherein when a difference between a maximum value and a minimum value of the characteristic spectrum at the preset wavelength is called a variation range, if the difference value is within ±15% of the variation range, the two adjacent measurement positions are determined to be included in a common effective measurement section.

18. The apparatus of claim 12, wherein the singular point is the wavelength of the light at a position where multiple types of characteristic spectra obtained in areas of the substrate surface with different structures intersect, or when the multiple types of characteristic spectra do not intersect, the wavelength of the light at a position where a difference between values ​​of the multiple types of characteristic spectra is minimum.

19. The apparatus of claim 12 , wherein the step of acquiring the data set comprises acquiring the characteristic spectrum during a period in which the light source is moving.

20. The apparatus according to claim 12 , wherein the step of acquiring the data set comprises alternating between moving and stopping the light source, and acquiring the characteristic spectrum during a period when the light source is stopped.

21. The apparatus of claim 12 , wherein the inspection unit comprises a hyperspectral camera.

22. The illumination range of the hyperspectral camera is set to an elongated rectangular shape whose longitudinal dimension is larger than the diameter of the substrate, The apparatus according to claim 21 , wherein the irradiation range is moved in a fixed direction relative to the plurality of substrates placed on the stage, thereby scanning the entire surfaces of the substrates.

23. 23. An apparatus according to claim 22; a rotation axis for rotating the stage; a processing vessel containing the stage on which the plurality of substrates are placed and which revolves around the rotation axis; a processing gas supply unit for supplying a processing gas to the substrate; Equipped with the substrate processing apparatus measures a film thickness of the substrate after processing the substrate placed on the stage by supplying the processing gas to the substrate.

Images