Inspection system

Abstract

To provide a technique for measuring a temperature distribution of at least one of a substrate and an edge ring supported on a stage.SOLUTION: An inspection system 1 comprises: a chamber 20; a lid member 21 provided at an upper end portion of the chamber; a wavelength sweeping light source 31 configured to generate measuring light whose wavelength changes with time, the measuring light having a wavelength that passes through the lid member, the substrate, and the edge ring; a lens 40 configured to emit the measuring light from the wavelength sweeping light source toward a stage 22 supporting the substrate and the edge ring through the lid member and to receive return light, and having an outer diameter larger than that of the substrate or the edge ring; an image sensor 43 that has pixels two-dimensionally arrayed and measures a spectrum of the return light made incident on the lens for each pixel; and a controller that calculates a two-dimensional temperature distribution of at least one of the substrate and the edge ring on the basis of the spectrum of the return light measured by the image sensor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY Exemplary embodiments of the present disclosure relate to an inspection system. [Background technology]

[0002] Patent Document 1 discloses a system for measuring the temperature of a substrate placed on a stage of a substrate processing apparatus. This system uses near-infrared light that can pass through silicon as measurement light, and measures the temperature of the substrate by irradiating the substrate with the near-infrared light through an upper electrode. Patent Document 2 discloses a system for measuring the temperature of a substrate without teaching an initial temperature, based on the interference of infrared light in two wavelength ranges. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-127087 A [Patent Document 2] Patent Publication No. 2021-060276 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a system capable of measuring the temperature distribution of at least one of a substrate and an edge ring supported on a stage. [Means for solving the problem]

[0005] One aspect of the present disclosure is an inspection system. The inspection system includes a chamber, a lid member, a swept light source, a lens, an image sensor, and a control unit. The chamber is configured to provide a space therein and to accommodate a stage in the space. The upper surface of the stage includes a first support surface that supports a substrate and a second support surface that surrounds the first support surface and supports an edge ring. The stage is configured to adjust the temperature of at least one of the substrate supported on the first support surface and the edge ring supported on the second support surface. The lid member is provided at an upper end of the chamber and defines a space. The swept light source is configured to generate measurement light whose wavelength changes over time based on a control signal that varies continuously. The measurement light has a wavelength that is transmitted through the lid member, the substrate, and the edge ring. The lens is configured to emit the measurement light from the swept light source through the lid member toward the stage on which the substrate and the edge ring are supported, and to input the return light. The lens has an outer diameter larger than the substrate or the edge ring. The image sensor has pixels that are two-dimensionally arranged, and measures the spectrum of the return light incident on the lens for each pixel. The controller calculates a two-dimensional temperature distribution of at least one of the substrate and the edge ring based on the spectrum of the returned light measured by the image sensor. Effect of the Invention

[0006] According to the present disclosure, it is possible to measure the temperature distribution of at least one of a substrate and an edge ring supported on a stage. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of an example of an inspection system according to an example embodiment. [Diagram 2] FIG. 2 is a schematic diagram of another example of an inspection system according to an exemplary embodiment. [Diagram 3] FIG. 3 is a schematic diagram of another example of an inspection system according to an exemplary embodiment. [Figure 4] FIG. 4 is a schematic diagram of another example of an inspection system according to an example embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Various exemplary embodiments will be described below. An electrostatic chuck (ESC: Electric Static Chuck) provided in a substrate processing apparatus such as a dry etching apparatus may have a plurality of heaters to control the temperature within the surface of the substrate. In order to control these heaters, the temperature in the vicinity of the heaters is measured. For example, a temperature sensor is disposed in a position close to the heater to measure the temperature. Alternatively, the temperature at the location where the heater is disposed is estimated based on the resistance value of a circuit that controls the heater. In order to realize more accurate control of the substrate temperature, it is preferable to reduce the manufacturing tolerance of the electrostatic chuck. By performing temperature calibration of the electrostatic chuck in the manufacturing process of the electrostatic chuck, the influence of the manufacturing tolerance of the electrostatic chuck on the temperature control can be suppressed.

[0009] In temperature calibration, calibration is performed with the temperature of the substrate placed on the electrostatic chuck as a reference, thereby realizing calibration that takes heat transfer to the substrate into consideration. A radiation thermometer, a thermal image sensor, a temperature measurement wafer, etc. are used to measure the temperature distribution of the substrate. However, with these methods, it is difficult to simultaneously satisfy all of the following: temperature measurement of all heaters, a wide measurable temperature range from a low temperature range of -40°C or less to a high temperature range of 200°C or more, and high temperature measurement accuracy (±1°C or less). The present disclosure provides an apparatus that can measure the temperature distribution of at least one of a substrate and an edge ring supported on a stage.

[0010] One aspect of the present disclosure is an inspection system. The inspection system includes a chamber, a lid member, a swept light source, a lens, an image sensor, and a control unit. The chamber is configured to provide a space therein and to accommodate a stage in the space. The upper surface of the stage includes a first support surface that supports a substrate and a second support surface that surrounds the first support surface and supports an edge ring. The stage is configured to adjust the temperature of at least one of the substrate supported on the first support surface and the edge ring supported on the second support surface. The lid member is provided at an upper end of the chamber and defines a space. The swept light source is configured to generate measurement light whose wavelength changes over time based on a control signal that varies continuously. The measurement light has a wavelength that is transmitted through the lid member, the substrate, and the edge ring. The lens is configured to emit the measurement light from the swept light source through the lid member toward the stage on which the substrate and the edge ring are supported, and to input the return light. The lens has an outer diameter larger than the substrate or the edge ring. The image sensor has pixels that are two-dimensionally arranged, and measures the spectrum of the return light incident on the lens for each pixel. The controller calculates a two-dimensional temperature distribution of at least one of the substrate and the edge ring based on the spectrum of the returned light measured by the image sensor.

[0011] In this inspection system, a measurement light is output from a wavelength swept light source. The wavelength of the measurement light changes with time. The measurement light, while changing its wavelength with time, is emitted through a cover member toward the stage by a lens having an outer diameter larger than that of the substrate or edge ring. The return light from the stage includes reflected light from the substrate or edge ring. The wavelength of the return light changes with time, similar to the measurement light. The return light is detected pixel by pixel by an image sensor having pixels arranged two-dimensionally. Each pixel detects return light from a certain location, which has changed in wavelength. Then, a spectrum is measured for each pixel. The temperature of each pixel is calculated based on the spectrum for each pixel. The inspection system can measure the temperature distribution of at least one of the substrate and the edge ring supported on the stage by emitting the measurement light using a large diameter lens. Then, the inspection system can collectively measure the temperature distribution at the same time by using the wavelength swept light source and the image sensor.

[0012] Another aspect of the present disclosure is an inspection system. The inspection system includes a chamber, a cover member, a broadband light source, a galvanometer scanner, a lens, a spectrometer, and a control unit. The chamber is configured to provide a space therein and to accommodate a stage in the space. The upper surface of the stage includes a first support surface that supports a substrate and a second support surface that surrounds the first support surface and supports an edge ring. The stage is configured to be able to adjust the temperature of at least one of the substrate supported on the first support surface and the edge ring supported on the second support surface. The cover member is provided at an upper end of the chamber and defines a space. The broadband light source is configured to generate measurement light having a broadband wavelength. The measurement light has a wavelength that is transmitted through the cover member, the substrate, and the edge ring. The galvanometer scanner is configured to control the emission direction of the measurement light from the broadband light source. The lens is configured to emit the measurement light from the galvanometer scanner through the cover member toward the stage on which the substrate and the edge ring are supported, and to receive return light. The lens has an outer diameter larger than the substrate or the edge ring. The spectrometer measures the spectrum of the return light incident on the lens for each irradiation position of the measurement light, and the control unit calculates a two-dimensional temperature distribution of at least one of the substrate and the edge ring based on the spectrum of the return light measured by the spectrometer.

[0013] In this inspection system, a measurement light is output from a broadband light source. The emission direction of the measurement light is controlled by a galvano scanner, and the measurement light is emitted through a cover member toward the stage by a lens having an outer diameter larger than that of the substrate or edge ring. By changing the emission direction of the measurement light, the measurement light is emitted to different positions of the substrate or edge ring. The return light from the stage includes reflected light at the position where the measurement light is irradiated. The return light is detected by a spectroscope for each emission direction, that is, for each position where the measurement light is irradiated, and the spectrum is measured. The temperature for each position is calculated based on the spectrum for each position where the measurement light is irradiated. In this way, the inspection system can measure the temperature distribution of at least one of the substrate and the edge ring supported on the stage by emitting the measurement light using a large diameter lens. Then, the inspection system can measure the temperature distribution by scanning the light beam using a broadband light source and a galvano scanner.

[0014] Various embodiments will be described in detail below with reference to the drawings. In the following description and in each drawing, the same or corresponding elements are given the same reference numerals, and redundant description will not be repeated. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper", "lower", "left" and "right" are based on the illustrated state and are for convenience.

[0015] [First embodiment] [Inspection system overview] Fig. 1 is a diagram illustrating an example of an inspection system according to an exemplary embodiment. The inspection system 1 illustrated in Fig. 1 inspects an electrostatic chuck. The inspection system 1 includes an inspection device 2 for operating the electrostatic chuck in the same environment as a general plasma processing apparatus, and an optical measurement system 3 for measuring the temperature of the substrate using light.

[0016] The inspection device 2 includes a chamber body 20 (an example of a chamber). The chamber body 20 has a substantially cylindrical shape and provides an internal space 20a. A ceiling portion of the chamber body 20 is composed of a lid member 21 provided at the upper end portion of the chamber body 20. The lid member 21 defines the internal space 20a. The lid member 21 is formed of a material that is transmissive to measurement light, which will be described later. The lid member 21 may be formed of, for example, silicon, sapphire, or quartz.

[0017] A stage 22 is disposed on the bottom of the chamber body 20. The stage 22 can be supported by a substantially cylindrical support made of an insulating material. The stage 22 has a lower electrode 23 and an electrostatic chuck 24. The lower electrode 23 is made of a conductive material such as aluminum, and has a substantially disk shape.

[0018] The electrostatic chuck 24 is provided on the lower electrode 23. A central region of the upper surface of the electrostatic chuck 24 is a first support surface 24a that supports a wafer W (an example of a substrate). The wafer W is made of silicon, for example. The electrostatic chuck 24 has a body formed of a dielectric material. A film-like electrode is provided in the body corresponding to the first support surface 24a of the electrostatic chuck 24. The electrode of the electrostatic chuck 24 is connected to an HV controller 25, and a voltage is applied to the electrode. The HV controller 25 is a device that controls a power supply, and may be a computer equipped with a processor, a storage unit, an input device, a display device, and the like. When a voltage is applied to the electrode of the electrostatic chuck 24, an electrostatic attractive force is generated between the electrostatic chuck 24 and the wafer W. The generated electrostatic attractive force attracts the wafer W to the electrostatic chuck 24, and the wafer W is held by the electrostatic chuck 24.

[0019] The region of the upper surface of the electrostatic chuck 24 surrounding the first support surface 24a is a second support surface 24b that supports an edge ring ER. The edge ring ER is provided to surround the edge of the wafer W in order to improve the in-plane uniformity of etching. The edge ring ER may be made of silicon, silicon carbide, quartz, or the like. A film-like electrode may be provided in the body of the electrostatic chuck 24 corresponding to the second support surface 24b. The electrode of the electrostatic chuck 24 is connected to the HV controller 25, and a voltage is applied thereto. When a voltage is applied to the electrode of the electrostatic chuck 24, an electrostatic attractive force is generated between the electrostatic chuck 24 and the edge ring ER. The generated electrostatic attractive force attracts the edge ring ER to the electrostatic chuck 24, and the edge ring ER is held by the electrostatic chuck 24.

[0020] A heater may be provided in the body of the electrostatic chuck 24. The heater is connected to the ESC controller 26, and a current is applied to the heater. The ESC controller 26 is a device for controlling a power supply, and may be a computer including a processor, a storage unit, an input device, a display device, and the like. A flow path is provided inside the lower electrode 23. A coolant is supplied to the flow path from a chiller unit 27 disposed outside the chamber body 20 through a pipe. The coolant supplied to the flow path is returned to the chiller unit 27 through the pipe. The inspection device 2 is provided with a He gas supply unit 28. The He gas supply unit 28 supplies He gas between the upper surface of the electrostatic chuck 24 and the rear surface of the wafer W and the rear surface of the edge ring ER. In the inspection device 2, the temperatures of the wafer W and the edge ring ER placed on the electrostatic chuck 24 are adjusted by heating by the heater and heat removal by the coolant and He gas.

[0021] An exhaust port is provided at the bottom of the chamber body 20. An exhaust device 29 is connected to the exhaust port. The exhaust device 29 has a pressure control valve and a vacuum pump such as a turbo molecular pump and a dry pump.

[0022] The inspection device 2 may further include a main controller 30. The main controller 30 may be a computer including a processor, a storage unit, an input device, a display device, and the like. The main controller 30 controls each unit of the inspection device 2 and the light measurement system 3. In the main controller 30, an operator can use the input device to input commands and the like to manage the inspection device 2 and the light measurement system 3. The storage unit of the main controller 30 stores control programs and setting values ​​for controlling various processes executed by the inspection device 2 and the light measurement system 3 using the processor.

[0023] [Outline of the optical measurement system] The optical measurement system 3 measures the temperatures of the wafer W and the edge ring ER based on the change in the optical thickness of the wafer W and the edge ring ER. The optical measurement system 3 converts the measured change in optical thickness into temperature based on a calibration curve that is a relationship between the optical thickness and temperature of the wafer W and the edge ring ER that has been acquired in advance. The optical measurement system 3 measures the temperature distribution of the wafer W and the edge ring ER by collectively measuring the interference signal using a two-dimensional image sensor.

[0024] In order to perform the above-mentioned functions, the light measurement system 3 includes a wavelength swept light source 31, a first lens 35, a beam splitter 36, a second lens 37, an object-side telecentric lens 40 (an example of a lens), a converging lens 42, an image sensor 43, and a signal processing device 47 (an example of a control unit).

[0025] The swept light source 31 receives a control signal that varies continuously over time from the signal processing device 47. The swept light source 31 generates measurement light whose wavelength varies over time based on the control signal. The measurement light has a wavelength that can be transmitted through the cover member 21, the wafer W, and the edge ring ER. The measurement light is, for example, infrared light with a wavelength of 1310 nm or 1550 nm.

[0026] The measurement light from the wavelength swept light source 31 is collimated by the first lens 35 and enters the beam splitter 36. The beam splitter 36 is configured to bend the traveling direction of the measurement light passing through the first lens 35 and irradiate the stage 22. Here, the beam splitter 36 changes the traveling direction of the measurement light incident horizontally to a vertical direction. The beam splitter 36 is configured by combining two right-angle prisms, for example. The beam splitter 36 may be configured as a half mirror.

[0027] The measurement light from the beam splitter 36 is expanded by the second lens 37. The measurement light expanded by the second lens 37 is incident on the object-side telecentric lens 40. The object-side telecentric lens 40 is a lens in which the principal ray is parallel to the lens optical axis on the object side. The object-side telecentric lens 40 has an outer diameter larger than the wafer W or the edge ring ER. The object-side telecentric lens 40 outputs the measurement light incident through the second lens 37 to at least one of the wafer W and the edge ring ER through the cover member 21. The object-side telecentric lens 40 outputs the measurement light parallel to the vertical direction to at least one of the wafer W and the edge ring ER. Note that a shield having the same diameter as the wafer W may be placed between the object-side telecentric lens 40 and the wafer W, so that the measurement light is irradiated only on the edge ring ER.

[0028] The measurement light incident on the stage 22 is reflected by the front and back surfaces of the wafer W, and enters the object-side telecentric lens 40 as returned light. That is, the returned light includes light reflected by the front surface of the wafer W and light reflected by the back surface of the wafer W. Similarly, the returned light includes light reflected by the front surface of the edge ring ER and light reflected by the back surface of the edge ring ER. The returned light passes through the second lens 37 and the beam splitter 36, and is converged by the converging lens 42. The converged returned light enters the image sensor 43.

[0029] The image sensor 43 has pixels arranged two-dimensionally. As an example, the image sensor 43 is a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) for the near-infrared region. Each pixel measures the spectrum of the returned light. Since the wavelength is swept, the spectrum has an intensity distribution that depends on the wavelength or frequency. In other words, one pixel functions as one photodetector, and the detection result of one pixel becomes the measurement result of the corresponding location on the wafer W or the edge ring ER. The image sensor 43 outputs the spectrum measured at each pixel to the signal processing device 47.

[0030] The signal processing device 47 may be a computer including a processor, a storage unit, an input device, a display device, etc. The signal processing device 47 calculates a two-dimensional temperature distribution of at least one of the wafer W and the edge ring ER based on the spectrum of the return light measured by the image sensor 43.

[0031] The signal processing device 47 processes the spectrum measured at each pixel. Each spectrum is processed by the same method. The signal processing device 47 performs a fast Fourier transform on the spectrum corresponding to a certain pixel. The signal processing device 47 calculates the position of the center of gravity of a predetermined peak value of the reflected light spectrum after the Fourier transform. The signal processing device 47 calculates the optical path length based on the position of the center of gravity. The signal processing device 47 calculates the temperature of at least one of the wafer W and the edge ring ER based on the optical path length. The signal processing device 47 calculates the temperature by referring to temperature calibration data acquired in advance. The temperature calibration data indicates the relationship between the temperature and the optical path length, and is stored in advance in, for example, the memory unit of the signal processing device 47. The signal processing device 47 performs the process of calculating the above-mentioned temperature for the spectrum of all acquired pixels, and associates the measurement position of the wafer W or the edge ring ER with the calculated temperature. As a result, the signal processing device 47 calculates a two-dimensional temperature distribution of at least one of the wafer W and the edge ring ER.

[0032] The temperature distribution of at least one of the wafer W and the edge ring ER is used for calibrating the temperature of the electrostatic chuck 24. Thus, by calibrating the temperature of the electrostatic chuck 24 in the manufacturing process of the electrostatic chuck 24, it is possible to suppress the influence of the manufacturing tolerance of the electrostatic chuck 24 on the temperature control.

[0033] [Summary of Inspection System 1] In the inspection system 1, a measurement light is output from a wavelength swept light source 31. The wavelength of the measurement light changes with time. The measurement light is emitted toward the stage through a cover member by a lens having an outer diameter larger than at least one of the wafer W and the edge ring ER while changing the wavelength with time. The return light from the stage includes reflected light from the wafer W or the edge ring ER. The return light changes in wavelength with time, similar to the measurement light. The return light is detected pixel by pixel by an image sensor 43 having two-dimensionally arranged pixels. One pixel detects return light from a certain location, which has a changed wavelength. Then, a spectrum is measured for each pixel. The temperature for each pixel is calculated based on the spectrum for each pixel. The inspection system 1 can measure the temperature distribution of at least one of the wafer W and the edge ring ER supported on the stage 22 by emitting the measurement light using a large-diameter object-side telecentric lens 40. Then, the inspection system 1 can measure the temperature distribution at the same time collectively by using the wavelength swept light source 31 and the image sensor 43.

[0034] Conventional temperature measurement methods include thermal imaging sensors, or temperature measuring wafer sensors using thermocouples or resistance temperature detectors. Thermal imaging sensors are non-contact measurement methods and have high measurement spatial resolution. However, they require the use of special wafers coated with black body paint, and there is a concern that the black body paint may contaminate the ESC. Furthermore, since they include errors due to the lens field of view, the measurement uncertainty is large and the measurement accuracy is not good. In addition, the measurement range tends to be narrow. In particular, they cannot measure negative temperature ranges (below -40°C) or their measurement accuracy drops significantly. Temperature measuring wafer sensors have small measurement uncertainty and good measurement accuracy. However, they have low measurement spatial resolution and cannot measure the temperatures on all points of heaters arranged in multiple regions. In addition, they tend to have a narrow measurement range. In particular, they cannot measure the range from -100°C to 400°C with a single sensor or measurement method. If the temperature measuring wafer sensor is a wired sensor, the number of wires leading from the sensor to the measuring device increases depending on the number of measurement points, and care must be taken when handling them. Furthermore, with wired sensors, it is difficult to clean the back surface of the sensor wafer due to the electrical wires, and there is a concern that contamination may accumulate on the back surface and be transferred to the ESC after repeated use.

[0035] In contrast, inspection system 1 can measure temperatures in the range of -100°C to 400°C non-contact and with high accuracy (within ±1°C). Inspection system 1 does not require special treatment of the object being measured, such as applying black paint, reducing the risk of contamination. Inspection system 1 has spatial resolution that allows measurement at all points on the heater. Since inspection system 1 uses a non-contact measurement method, the object being measured is easy to handle.

[0036] [Second embodiment] Fig. 2 is a diagram illustrating another example of an inspection system according to an exemplary embodiment. The inspection system 1A illustrated in Fig. 2 is different from the inspection system 1 in that it uses two light sources and two image sensors, but is otherwise the same. The following description will focus on the differences between the inspection system 1A and the inspection system 1, and will omit redundant description.

[0037] The inspection system 1A includes an inspection device 2 and an optical measurement system 3A. The inspection device 2 is the same as that included in the inspection system 1. Like the optical measurement system 3, the optical measurement system 3A measures the temperature of the wafer W based on a change in the optical thickness of the wafer W. Compared to the optical measurement system 3, the optical measurement system 3A includes a first wavelength swept light source 31A and a second wavelength swept light source 31B instead of the wavelength swept light source 31.

[0038] The first wavelength swept light source 31A and the second wavelength swept light source 31B have the same configuration as the wavelength swept light source 31. The first wavelength swept light source 31A and the second wavelength swept light source 31B generate light in different wavelength regions. The first wavelength swept light source 31A generates light in a first wavelength region, and the second wavelength swept light source 31B generates light in a second wavelength region.

[0039] The first wavelength swept light source 31A and the second wavelength swept light source 31B are connected to a WDM (Wavelength Division Multiplexing) coupler 33. The WDM coupler 33 multiplexes light in the first wavelength region and light in the second wavelength region. The multiplexed measurement light is output to a first lens 35 from an output end 34, which is an end of a fiber.

[0040] The first lens 35, the beam splitter 36, the second lens 37, and the object-side telecentric lens 40 are the same as those in the inspection system 1. That is, the measurement light is collimated by the first lens 35 and enters the beam splitter 36. The measurement light is bent in the vertical direction by the beam splitter 36. The measurement light from the beam splitter 36 is expanded by the second lens 37. The measurement light expanded by the second lens 37 enters the object-side telecentric lens 40. The measurement light is collimated in the vertical direction by the object-side telecentric lens 40 and is emitted to at least one of the wafer W and the edge ring ER. The return light passes through the object-side telecentric lens 40, the second lens 37, and the beam splitter 36 in this order.

[0041] Compared to the light measurement system 3, the light measurement system 3A includes a dichroic mirror 41, a first converging lens 42A, a first image sensor 43A, a second converging lens 42B, and a second image sensor 43B instead of the converging lens 42 and the image sensor 43. That is, the number of image sensors is increased to two. The dichroic mirror 41 separates the return light into return light in a first wavelength region and return light in a second wavelength region. The first converging lens 42A and the second converging lens 42B have the same configuration as the converging lens 42. The first image sensor 43A and the second image sensor 43B have the same configuration as the image sensor 43. In addition, the first image sensor 43A and the second image sensor 43B may be configured using image sensors having different sensitivity wavelength regions.

[0042] The dichroic mirror 41 is disposed after the beam splitter 36 and distributes the return light transmitted through the beam splitter 36 to two systems, a first image sensor 43A and a second image sensor 43B. The return light in the first wavelength region transmitted through the dichroic mirror 41 is converged by a first converging lens 42A and enters the first image sensor 43A. The return light in the second wavelength region bent in the horizontal direction by the dichroic mirror 41 is converged by a second converging lens 42B and enters the second image sensor 43B. Each pixel of the first image sensor 43A and the second image sensor 43B measures the spectrum of the return light.

[0043] The signal processing device 47 has the same configuration as that of the inspection system 1. The signal processing device 47 calculates a two-dimensional temperature distribution of at least one of the wafer W and the edge ring ER based on the spectrum of the return light measured at each pixel of the first image sensor 43A and the second image sensor 43B. The method of calculating the temperature distribution of the signal processing device 47 is different from that of the inspection system 1 in the calculation method of the temperature at each pixel, and the rest is the same. The signal processing device 47 calculates the temperature using the same method as the algorithm described in JP 2021-060276 A. For example, the signal processing device 47 calculates an optical path length ratio, which is the ratio between the first optical path length related to the measurement light in the first wavelength region and the second optical path length related to the measurement light in the second wavelength region. The signal processing device 47 calculates the position of the center of gravity of a predetermined peak value of the spectrum, calculates the first optical path length and the second optical path length at the position of the center of gravity, and obtains the optical path length ratio. In the configuration of FIG. 2, the same position of the same measurement target is measured in the first wavelength region and the second wavelength region, so that the optical path length ratio is synonymous with the refractive index ratio of each wavelength region. The signal processing device 47 calculates the temperature of the wafer W or the edge ring ER based on the optical path length ratio and a previously acquired relationship between the refractive index ratio and the temperature of the wafer W or the edge ring ER. The refractive index ratio is a ratio between a first refractive index, which is the refractive index of the wafer W or the edge ring ER with respect to the measurement light in the first wavelength region, and a second refractive index, which is the refractive index of the wafer W or the edge ring ER with respect to the measurement light in the second wavelength region.

[0044] [Summary of Inspection System 1A] The inspection system 1A can achieve the same effects as the inspection system 1, and can simplify the measurement procedure. Specifically, the temperature calibration data used in the inspection system 1 must be prepared by actually measuring the relationship between the current temperature and the normalized optical path length, which is normalized by the optical path length at the reference temperature when the calibration curve is created, for each of the wafer W and the edge ring ER in order to teach the current temperature. In contrast, the inspection system 1A uses an optical path length ratio, and therefore does not need to obtain in advance actual measurement data of the optical path length and temperature of each of the wafer W and the edge ring ER. Therefore, the inspection system 1A can simplify the measurement procedure more than the inspection system 1.

[0045] [Third embodiment] FIG. 3 is a diagram illustrating another example of an inspection system according to an exemplary embodiment. The inspection system 1B illustrated in FIG. 3 is significantly different from the inspection system 1 in that it uses a broadband light source that does not have a wavelength sweeping function. The inspection system 1B includes a spectrometer instead of an image sensor to calculate temperature based on light from the broadband light source. The inspection system 1B also includes a light beam scanning function instead of a batch irradiation function to measure temperature distribution. The inspection system 1B is otherwise the same as the inspection system 1. The following description will focus on the differences between the inspection system 1B and the inspection system 1, and overlapping descriptions will be omitted.

[0046] The inspection system 1B includes an inspection device 2 and an optical measurement system 3B. The inspection device 2 is the same as that included in the inspection system 1. Like the optical measurement system 3, the optical measurement system 3B measures the temperature of the wafer W based on a change in the optical thickness of the wafer W. Compared to the optical measurement system 3, the optical measurement system 3B includes a broadband light source 32 instead of the swept light source 31.

[0047] The broadband light source 32 is a light source having a certain bandwidth (generally 40 nm to 100 nm or more) unlike the single wavelength of a laser. The broadband light source 32 is, for example, an SLD (Super Luminescent Diode), an ASE (Amplified Spontaneous Emission), or an LED (Light-Emitting Diode). The measurement light generated by the broadband light source 32 has a wavelength that transmits the cover member 21, the wafer W, and the edge ring ER.

[0048] The broadband light source 32 emits measurement light from an output end 34, which is an end of a fiber, to a first lens 35. The first lens 35 and the beam splitter 36 are the same as those in the inspection system 1. That is, the measurement light is collimated by the first lens 35 and enters the beam splitter 36. The measurement light is bent in the vertical direction by the beam splitter 36.

[0049] The measurement light bent by the beam splitter 36 has its emission direction controlled by a first galvanometer scanner 38 (an example of a galvanometer scanner) and a second galvanometer scanner 39 (an example of a galvanometer scanner). The galvanometer scanner uses a reflecting mirror to control the measurement light beam in any direction, and irradiates the measurement light at a predetermined position on the wafer W or edge ring ER. The first galvanometer scanner 38 controls the irradiation position in the Y direction. The second galvanometer scanner 39 controls the irradiation position in the X direction. The light from the second galvanometer scanner 39 is incident on an object-side telecentric lens 40.

[0050] The object-side telecentric lens 40 is the same as that in the inspection system 1. That is, the first galvanometer scanner 38 and the second galvanometer scanner 39 determine an in-plane irradiation position, and the measurement light is emitted toward the determined irradiation position. The measurement light is converted into parallel light in the vertical direction by the object-side telecentric lens 40 and is emitted to at least one of the wafer W and the edge ring ER. The return light passes through the object-side telecentric lens 40, the second galvanometer scanner 39, the first galvanometer scanner 38, the beam splitter 36, and the convergent lens 42 in this order.

[0051] The return light converged by the converging lens 42 propagates through the fiber via an input end 44, which is the end of the fiber, and its spectrum is measured by a multichannel spectrometer 46. The multichannel spectrometer disperses the light using a grating or the like and measures the spectrum using a CCD (Charge Coupled Device) array or the like.

[0052] The signal processing device 47 has the same configuration as that of the inspection system 1. The signal processing device 47 stores the spectrum obtained by the multichannel spectrometer 46 in association with the irradiation position. The signal processing device 47 calculates the two-dimensional temperature distribution of at least one of the wafer W and the edge ring ER by calculating the temperature for each irradiation position from the spectrum corresponding to the irradiation position. The method of calculating the temperature of the signal processing device 47 is the same as that of the inspection system 1.

[0053] [Summary of Inspection System 1B] The inspection system 1B has the same effects as the inspection system 1.

[0054] [Fourth embodiment] Fig. 4 is a diagram illustrating another example of an inspection system according to an exemplary embodiment. The inspection system 1C illustrated in Fig. 4 is different from the inspection system 1B in that it uses two light sources and two spectroscopes, but is otherwise the same. The following description will focus on the differences between the inspection system 1C and the inspection system 1B, and will not be repeated.

[0055] The inspection system 1C includes an inspection device 2 and an optical measurement system 3C. The inspection device 2 is the same as that included in the inspection system 1B. Like the optical measurement system 3B, the optical measurement system 3C measures the temperature of the wafer W based on a change in the optical thickness of the wafer W. Compared to the optical measurement system 3B, the optical measurement system 3C includes a first broadband light source 32A and a second broadband light source 32B instead of the broadband light source 32.

[0056] The first broadband light source 32A and the second broadband light source 32B have the same configuration as the broadband light source 32. The first broadband light source 32A and the second broadband light source 32B generate light in different wavelength regions. The first broadband light source 32A generates light in a first wavelength region, and the second broadband light source 32B generates light in a second wavelength region.

[0057] The first broadband light source 32A and the second broadband light source 32B are connected to a WDM coupler 33. The WDM coupler 33 combines the light in the first wavelength region with the light in the second wavelength region. The combined measurement light is output to a first lens 35 from an output end 34, which is an end of the fiber.

[0058] The first lens 35, the beam splitter 36, the first galvanometer scanner 38, the second galvanometer scanner 39, and the object-side telecentric lens 40 are the same as those in the inspection system 1B. That is, the measurement light is collimated by the first lens 35 and enters the beam splitter 36. The measurement light is bent in the vertical direction by the beam splitter 36. The first galvanometer scanner 38 and the second galvanometer scanner 39 control the emission direction of the measurement light bent by the beam splitter 36. The first galvanometer scanner 38 and the second galvanometer scanner 39 determine the irradiation position in the plane, and the measurement light is emitted toward the determined irradiation position. The measurement light is collimated in the vertical direction by the object-side telecentric lens 40 and is emitted to at least one of the wafer W and the edge ring ER. The returning light passes through the object side telecentric lens 40, the second galvanometer scanner 39, the first galvanometer scanner 38, the beam splitter 36, and the converging lens 42 in this order.

[0059] The return light converged by the convergent lens 42 propagates through the fiber via an input end 44, which is the end of the fiber, and is split into two by a WDM splitter 45 according to wavelength.

[0060] Compared to the optical measurement system 3B, the optical measurement system 3C includes a first multichannel spectrometer 46A and a second multichannel spectrometer 46B instead of the multichannel spectrometer 46. The first multichannel spectrometer 46A and the second multichannel spectrometer 46B are configured to be able to measure the wavelength range of the first wavelength region and the wavelength range of the second wavelength region, respectively.

[0061] The signal processing device 47 has the same configuration as that of the inspection system 1B. The signal processing device 47 calculates a two-dimensional temperature distribution of at least one of the wafer W and the edge ring ER based on the spectrum of the return light measured by the first multichannel spectrometer 46A and the second multichannel spectrometer 46B. The method of calculating the temperature distribution of the signal processing device 47 is different from that of the inspection system 1B in the calculation method of the temperature at each irradiation position, and the rest is the same. The signal processing device 47 calculates the temperature using the same method as the algorithm described in JP 2021-060276 A. For example, the signal processing device 47 calculates an optical path length ratio, which is the ratio between the first optical path length related to the measurement light in the first wavelength region and the second optical path length related to the measurement light in the second wavelength region, similar to the inspection system 1A. The signal processing device 47 calculates the center of gravity of a predetermined peak value of the spectrum, calculates the first optical path length and the second optical path length at the center of gravity position, and obtains the optical path length ratio. In the configuration of Fig. 4, the same position of the same measurement target is measured in the first wavelength region and the second wavelength region, so the optical path length ratio is synonymous with the refractive index ratio of each wavelength region. The signal processing device 47 calculates the temperature of the wafer W or the edge ring ER based on the optical path length ratio and the previously acquired relationship between the refractive index ratio and the temperature of the wafer W or the edge ring ER. The refractive index ratio is the ratio between a first refractive index, which is the refractive index of the wafer W or the edge ring ER with respect to the measurement light in the first wavelength region, and a second refractive index, which is the refractive index of the wafer W or the edge ring ER with respect to the measurement light in the second wavelength region.

[0062] [Summary of Inspection System 1C] The inspection system 1C has the same effects as the inspection system 1B, and can simplify the measurement procedure like the inspection system 1A.

[0063] (Modification) It will be understood that various modifications of the exemplary embodiments of the present disclosure may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various exemplary embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

[0064] 1 to 4, by utilizing optical interference between light reflected from the bottom surface of the lid member 21 and light reflected from the surface of the wafer W, the distance between the bottom surface of the lid member 21 and the surface of the wafer W can be measured at any position. This makes it possible to measure not only the temperature distribution of the wafer W but also the distorted shape of the electrostatic chuck 24 during temperature measurement. The wafer W may be replaced with an edge ring ER and the distorted shape of the electrostatic chuck 24 may be measured using the same method. [Explanation of symbols]

[0065] 1, 1A, 1B, 1C... inspection system, 20... chamber body (an example of a chamber), 21... lid member, 22... stage, 31... wavelength swept light source, 32... broadband light source, 38... first galvanometer scanner (an example of a galvanometer scanner), 39... second galvanometer scanner (an example of a galvanometer scanner), 40... object side telecentric lens (an example of a lens), 43... image sensor, 47... signal processing device (an example of a control unit).

Claims

1. a chamber configured to provide a space therein and to house a stage in the space, an upper surface of the stage including a first support surface for supporting a substrate and a second support surface surrounding the first support surface and supporting an edge ring, the stage configured to be able to adjust a temperature of at least one of the substrate supported on the first support surface and the edge ring supported on the second support surface; A cover member provided at an upper end of the chamber and defining the space; a swept light source configured to generate measurement light having a wavelength that changes over time based on a continuously varying control signal, the measurement light having a wavelength that is transmitted through the lid member, the substrate, and the edge ring; and a lens configured to emit the measurement light from the wavelength swept light source toward the stage on which the substrate and the edge ring are supported, via the lid member, and to receive return light, the lens having an outer diameter larger than that of the substrate or the edge ring; an image sensor having pixels arranged two-dimensionally and configured to measure, for each pixel, a spectrum of the return light incident on the lens; a control unit that calculates a two-dimensional temperature distribution of at least one of the substrate and the edge ring based on the spectrum of the return light measured by the image sensor; An inspection system comprising:

2. a chamber configured to provide a space therein and to house a stage in the space, an upper surface of the stage including a first support surface for supporting a substrate and a second support surface surrounding the first support surface and supporting an edge ring, the stage configured to be able to adjust a temperature of at least one of the substrate supported on the first support surface and the edge ring supported on the second support surface; A cover member provided at an upper end of the chamber and defining the space; a broadband light source configured to generate measurement light having a broad band of wavelengths, the measurement light having a wavelength that is transmitted through the lid member, the substrate, and the edge ring; a galvanometer scanner configured to control an emission direction of the measurement light from the broadband light source; a lens configured to emit the measurement light from the galvano scanner toward the stage on which the substrate and the edge ring are supported, via the lid member, and to receive return light, the lens having an outer diameter larger than that of the substrate or the edge ring; a spectroscope that measures a spectrum of the return light incident on the lens for each irradiation position of the measurement light; a control unit that calculates a two-dimensional temperature distribution of at least one of the substrate and the edge ring based on the spectrum of the return light measured by the spectroscope; An inspection system comprising:

Images