Height measuring device, exposure device, and method for manufacturing articles

Abstract

This technology provides advantages for measuring the height of a substrate quickly and with high accuracy using optical measuring instruments and air sensors. [Solution] The height measuring device comprises an optical measuring instrument for measuring the height of a substrate, an air sensor for measuring the height of the substrate based on the pressure in the conduit while discharging air through the conduit, a member having a reference surface, and a controller for correcting the result of measuring the height of a second measurement point on the substrate by the optical measuring instrument based on a first result obtained by measuring the height of a first measurement point on the substrate and the height of the reference surface using the optical measuring instrument, and a second result obtained by measuring the height of the first measurement point on the substrate and the height of the reference surface using the air sensor.

Description

Technical Field

[0001] The present invention relates to a height measuring device, an exposure device, and an article manufacturing method.

Background Art

[0002] Patent Document 1 describes a lithographic projection apparatus having a first sensor that is a process-independent sensor such as an air micrometer and a second sensor that is a process-dependent sensor. The measured value by the second sensor has an offset error (PDOE) that may depend on the process. The lithographic projection apparatus can be executed for a plurality of positions on the substrate by scanning the substrate directly below the first and second sensors. Using the measured values obtained by the first and second sensors, a map in which the PDOE of the second sensor is stored for each position on the measured substrate is created. Since the measurement by the first sensor, which is a process-independent sensor, is slow, when measurements are executed for a plurality of positions on the substrate by scanning the substrate directly below the first and second sensors, a considerably long time is required for the measurement.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a technique advantageous for measuring the height of a substrate with high accuracy in a short time using an optical measuring instrument and an air sensor.

Means for Solving the Problems

[0005] One aspect of the present invention relates to a height measuring device, the height measuring device comprising: an optical measuring instrument for measuring the height of a substrate; an air sensor for measuring the height of the substrate based on the pressure in a conduit while discharging air through the conduit; a member having a reference surface; and a controller for correcting the result of measuring the height of a second measurement point on the substrate by the optical measuring instrument based on a first result obtained by measuring the height of a first measurement point on the substrate and the height of the reference surface using the optical measuring instrument, and a second result obtained by measuring the height of the first measurement point on the substrate and the height of the reference surface using the air sensor. [Effects of the Invention]

[0006] According to the present invention, an advantageous technique is provided for measuring the height of a substrate with high accuracy in a short time using an optical measuring instrument and an air sensor. [Brief explanation of the drawing]

[0007] [Figure 1A] A schematic diagram showing the configuration of an exposure apparatus according to one embodiment, which incorporates a height measuring device according to one embodiment. [Figure 1B] A schematic diagram showing the configuration of an exposure apparatus according to one embodiment, which incorporates a height measuring device according to one embodiment. [Figure 1C] A schematic diagram showing the configuration of an exposure apparatus according to one embodiment, which incorporates a height measuring device according to one embodiment. [Figure 2] A schematic diagram showing the top view of the circuit board stage. [Figure 3A] A schematic diagram showing an example of an air sensor configuration. [Figure 3B] A schematic diagram showing other configuration examples of an air sensor. [Figure 4] A flowchart illustrating the flow of a height measurement method in an exposure apparatus or height measuring apparatus. [Figure 5] A diagram illustrating how optical measuring instruments can be misleading in measurements. [Figure 6] A diagram illustrating Examples 1 and 2. [Modes for carrying out the invention]

[0008] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0009] Figures 1A, 1B, and 1C schematically show the configuration of an exposure apparatus EXP in one embodiment, which incorporates a height measuring device HM of one embodiment. The optical apparatus EPX may include an illumination optical system 62 for illuminating a master plate 61, and a projection optical system 3 for projecting the pattern of the master plate 61 onto the substrate 1. The exposure apparatus EXP may be configured to expose the substrate 1 by projecting the pattern of the master plate 61 onto the substrate 1 using the projection optical system 3. The exposure apparatus EPX may include a positioning system PS including a substrate stage 41 for holding the substrate 1, and a height measuring device HM for measuring the height of the substrate 1. The positioning system PS includes a stage measuring system MS for measuring the position and orientation of the substrate stage 41, and can control the position and orientation of the substrate stage 41 based on the output of the stage measuring system MS. The stage measuring system MS may include a plurality of measuring instruments, for example, measuring instruments 42, 43. The stage measuring system MS can measure the substrate stage 41 in six axes using the plurality of measuring instruments. The positioning system PS can control the substrate stage 41 in six axes based on the output of the measurement system MS. The multiple measuring instruments may include, for example, multiple interferometers, multiple encoders, or one or more interferometers and one or more encoders.

[0010] The exposure apparatus EXP or height measuring apparatus HM may include an optical measuring instrument OM for measuring the height of the substrate 1 and an air sensor 21 for measuring the height of the substrate 1. The optical measuring instrument OM may be an oblique incidence measuring instrument that irradiates light onto the surface to be measured and receives reflected light from the surface to be measured, and may include a light projector 12 that projects patterned light onto the surface to be measured and a light receiver 13 that receives reflected light from the surface to be measured. As will be described later, in the optical measuring instrument OM, light is reflected not only from the outermost surface of the substrate 1 but also from the internal structure of the substrate 1 (structures existing below the outermost surface), so measurement errors dependent on the internal structure of the substrate 1 may occur. The air sensor 21 may also be called an air microsensor. The air sensor 21 may be configured to measure the height of the substrate 1 with a resolution of the nanometer order or higher than 1 nm. The air sensor 21 may be configured to measure the height of the substrate 1 based on the pressure in a conduit while discharging air through the conduit. As will be described later, the measurement results from the air sensor 21 are not affected by the internal structure of the circuit board 1.

[0011] The exposure apparatus EXP or height measuring apparatus HM may include a reference plate 2 as the position of a member having a reference surface RS, and a controller 63. The reference plate 2 may have reference marks whose position is detected by an alignment sensor (not shown), for example, and may be placed on a substrate stage 41. The reference surface RS may be a flat surface. The controller 63 may consist of a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit), or a general-purpose or dedicated computer with a program built in, or a combination of all or part of these. The controller 63 may acquire a first result by measuring the height of a first measurement point on the substrate 1 and the height of the reference surface RS on the reference plate 2 using an optical measuring instrument OM. The controller 63 may also acquire a second result by measuring the height of a first measurement point on the substrate 1 and the height of the reference surface RS on the reference plate 2 using an air sensor 21. The controller 63 can also correct the measurement result of the second measurement point on the substrate 1 using the optical measuring instrument OM based on the first result and the second result. For example, the controller 63 can generate correction information to correct the measurement result of the second measurement point on the substrate 1 using the optical measuring instrument OM based on the first result and the second result. For example, the controller 63 can generate correction information based on the difference between the first result and the second result. By correcting the measurement result of the height of the second measurement point on the substrate 1 using the optical measuring instrument OM based on the correction information, the controller 63 can obtain height information of the second measurement point quickly and with high accuracy.

[0012] The first result may be the difference between the result of measuring the height of a first measurement point on substrate 1 (for example, a specific point within the shot area) using the optical measuring instrument OM and the result of measuring the height of the reference surface RS using the optical measuring instrument OM. Alternatively, the first result may be the difference between the average of the results of measuring the heights of multiple first measurement points on substrate 1 (for example, multiple specific points within the shot area) using the optical measuring instrument OM and the result of measuring the height of the reference surface RS using the optical measuring instrument OM.

[0013] The second result may be the difference between the result of measuring the height of a first measurement point on the substrate 1 (for example, a specific point within the shot area) using the air sensor 21 and the result of measuring the height of the reference surface RS using the air sensor 21. Alternatively, the second result may be the difference between the average of the results of measuring the heights of multiple first measurement points on the substrate 1 (for example, multiple specific points within the shot area) using the air sensor 21 and the result of measuring the height of the reference surface RS using the air sensor 21.

[0014] Figure 1A schematically shows how the height of the first measurement point on the substrate 1 is measured by the optical measuring instrument OM, and how the height of the reference surface RS is measured using the air sensor 21. Figure 1B schematically shows how the height of the first measurement point on the substrate 1 is measured using the air sensor 21. Figure 1C schematically shows how the height of the reference surface RS is measured by the optical measuring instrument OM.

[0015] Figure 2 schematically shows a top view of the substrate stage 41. Additional reference plates 4 and 5 may be placed on top of the substrate stage 41. Reference plates 4 and 5 may have reference marks. The thermal deformation of the top plate of the substrate stage 41 can be evaluated by measuring the positions of the reference marks on reference plates 2, 4, and 5 using an off-axis scope (not shown).

[0016] FIG. 3A schematically shows a configuration example of the air sensor 21. The air sensor 21 may include a reference nozzle 22 that discharges air through the first pipeline 71, a measurement nozzle 23 that discharges air through the second pipeline 72, and a differential pressure sensor 25 that detects the difference between the pressure in the first pipeline 71 and the pressure in the second pipeline 72. The air sensor 21 may further include a mass flow controller 28, and air may be supplied to the reference nozzle 22 and the measurement nozzle 23 via the mass flow controller 28. Air may be supplied to the mass flow controller 28 from an air supply source 31. A filter 29 and a valve 30 may be arranged between the mass flow controller 28 and the air supply source 31. The exposure apparatus EXP or the height measurement apparatus HM may include a drive mechanism (e.g., a lifting mechanism) 24 that moves the air sensor 21. The mass flow controller 28 may supply air to the reference nozzle 22 and the measurement nozzle 23 via a sensor 27 such as a pressure gauge or a flow meter. The air sensor 21 may further include a processor 26, and the processor 26 may convert the output of the differential pressure sensor 25 into height information. The reference nozzle 22 and the measurement nozzle 23 may be provided with orifices 34 at their respective inlets and outlets.

[0017] The mass flow controller 28 supplies air with a constant pressure and flow rate to the reference nozzle 22 and the measurement nozzle 23. The mass flow controller 28 may operate to maintain the pressure on the outlet side of the mass flow controller 28 at a predetermined pressure (e.g., 70 kPa ± 0.01 kPa) based on the output of the sensor 27. The diameter of the orifice 34 may be, for example, within the range of 0.1 to 0.2 mm. Since the orifice 34 acts as a resistance to the air flow, the pressure in the first pipeline 71 of the reference nozzle 22 can be maintained constant. The pressure in the second pipeline 72 of the measurement nozzle 23 becomes a value corresponding to the distance between the measurement nozzle 23 and the measured surface, and the differential pressure sensor 25 is provided with the pressure in the first pipeline 71 of the reference nozzle 22 and the pressure in the second pipeline 72 of the measurement nozzle 23. Therefore, a differential pressure corresponding to the distance between the measurement nozzle 23 and the measured surface is supplied to the differential pressure sensor 25. In the air sensor 21, no measurement error occurs due to the internal structure that may exist below the measurement target surface.

[0018] The output voltage of the differential pressure sensor 25 may depend on the diameter of the orifice 34. Increasing the diameter of the orifice 34 increases the measurement resolution, but also enlarges the working distance and shortens the time required for measurement. Conversely, decreasing the diameter of the orifice 34 decreases the measurement resolution, but also reduces the working distance and lengthens the time required for measurement. For example, the diameter of the orifice 34 can be determined such that when the height of the reference plane RS changes by 1 nm, the output voltage of the differential pressure sensor 25 changes by 2 mV. At this time, the working distance is, for example, 35 micrometers.

[0019] The controller 63 can calibrate the air sensor 21 based on the output of the air sensor 21 when the height of the substrate stage 41 is changed by a predetermined height in the positioning system PS. Calibration of the air sensor 21 may include the processor 26 updating the conversion formula for converting the output voltage of the differential pressure sensor 25 to height. The controller 63 may calibrate the air sensor 21 based on the change in the output of the differential pressure sensor 25 (for example, rising or falling by 1 nm each time) when the height of the substrate stage 41 is changed by a certain amount in the positioning system PS. The conversion formula is usually non-linear. The conversion formula may include a time drift component and / or a temperature-dependent component. The pedestal of the reference plate may be made of a metal or ceramic material with a low coefficient of thermal expansion, and the reference mark may be made of quartz glass.

[0020] The controller 63 can calibrate the air sensor 21 so that the result of measuring the height of the reference surface RS of the reference plate 2 by the air sensor 21 is 0. Alternatively, the controller 63 may hold the result of measuring the height of the reference surface RS of the reference plate 2 by the air sensor 21 as a reference value, and obtain a corrected measurement value by subtracting the reference value from the measurement value of the height measured at the measurement point by the air sensor 21. In this case, the operation of holding the reference value is calibration. Similarly, the controller 63 can calibrate the optical measuring instrument OM so that the result of measuring the height of the reference surface RS of the reference plate 2 by the optical measuring instrument OM is 0. Alternatively, the controller 63 may hold the result of measuring the height of the reference surface RS of the reference plate 2 by the optical measuring instrument OM as a reference value, and obtain a corrected measurement value by subtracting the reference value from the measurement value of the height measured at the measurement point by the optical measuring instrument OM. In this case, the operation of holding the reference value is calibration.

[0021] Since the air sensor 21 has a fairly large drift, calibration of the air sensor 21 may be performed frequently, for example, every 9 seconds.

[0022] In one example, after calibrating the air sensor 21 and the optical measuring instrument OM using the reference surface RS of the reference plate 2, the height of the first measurement point on the substrate 1 is measured by the air sensor 21 and the optical measuring instrument OM, respectively. If the difference between the results of measuring the height of the first measurement point on the substrate 1 by the air sensor 21 and the optical measuring instrument OM is greater than or equal to a predetermined value (e.g., 10 nm), the controller 63 may update or generate correction information. The controller 63 may update or generate correction information so that the measurement result from the optical measuring instrument OM matches the measurement result from the air sensor 21.

[0023] Figure 3B schematically shows another configuration example of the air sensor 21. In the configuration example shown in Figure 3B, the sensor reference surface 33 is provided so as to face the reference nozzle 22.

[0024] Figure 4 is a flowchart showing the flow of the height measurement method in the exposure apparatus EXP or the height measuring apparatus HM. This height measurement method is controlled by the controller 63 and can be performed, for example, at the beginning of a lot or the beginning of a recipe. In one example, the working distance of the air sensor 21 may be limited to several tens of micrometers in order to achieve a resolution of several nanometers. There is a trade-off relationship between resolution and working distance. When moving the substrate stage 41 along the XY plane, it is necessary to drive the substrate stage 41 in the Z direction, TiltX, and TiltY in order to adjust for the running error of the substrate stage 41 and the tilt of the substrate 1 during exposure. Therefore, in order to prevent the substrate stage 41 from colliding with the tips of the reference nozzle 22 and measurement nozzle 23 of the air sensor 21, it is desirable to retract the air sensor 21 by the drive mechanism 24 after the measurement by the air sensor 21 is completed. The drive mechanism 24 may include, for example, a lifting mechanism and / or a horizontal drive mechanism. Furthermore, when performing measurements using the air sensor 21, it is necessary to move the air sensor 21 from the retracted position to the measurement position using the drive mechanism 24 and wait for the air sensor 21 to settle down.

[0025] The process will be explained with reference to Figure 4. In step S401, the controller 63 measures a predetermined area (an area without a reference mark) on the flat surface of the reference plate 2 on the substrate stage 41 using the air sensor 21 and the optical measuring instrument OM, respectively, and stores the measurement results as Ar and Or. At this time, calibration (or teaching) may be performed so that the measurement results from the air sensor 21 and the optical measuring instrument OM become 0. In this measurement, the positioning device PS positions the substrate stage 41 in terms of X, Y, Z, θX, θY, and θZ based on the output of the measurement system MS. Note that θX, θY, and θZ are rotations around the X axis, Y axis, and Z axis, respectively. The area measured by the air sensor 21 and the area measured by the optical measuring instrument OM are usually different. Therefore, the position of the substrate stage 41 when the predetermined area of ​​the reference plate 2 is measured by the air sensor 21 is different from the position of the substrate stage 41 when the predetermined area of ​​the reference plate 2 is measured by the optical measuring instrument OM. The positioning system PS has sufficient positioning accuracy (e.g., resolution of 0.1 nm or less) to enable the air sensor 21 and optical measuring instrument OM to measure the same area (predetermined area) of the reference plate 2.

[0026] In step S402, the controller 63 measures the first measurement locations of the shot area of ​​the resist-coated substrate 1 on the substrate stage 41 using the air sensor 21 and the optical measuring instrument OM, respectively, and stores the measurement results as As and Os. Here, the controller 63 may use the average value of the results obtained by measuring multiple first measurement locations of the resist-coated substrate 1 on the substrate stage 41 using the air sensor 21 as As. Alternatively, the controller 63 may use the average value of the results obtained by measuring multiple first measurement locations of the resist-coated substrate 1 on the substrate stage 41 using the optical measuring instrument OM as As. The X and Y coordinates of the multiple first measurement locations measured by the air sensor 21 are the same as the X and Y coordinates of the multiple first measurement locations measured by the optical measuring instrument OM.

[0027] In process S403, the controller 63 calculates D = (As - Ar) - (Os - Or). ​​Here, (Os - Or) is the first result obtained by measuring the height between the first measurement point on the substrate 1 and the reference surface RS of the reference plate 2 using the optical measuring instrument OM. (As - Ar) is the second result obtained by measuring the height between the first measurement point on the substrate 1 and the reference surface RS of the reference plate 2 using the air sensor 21. D is the difference between the first result and the second result, and can be understood as the measurement error (amount of measurement error) of the optical measuring instrument OM caused by the internal structure of the substrate 1.

[0028] In step S404, the controller 63 determines whether D (measurement error amount) is less than a predetermined value (tolerance value). If D (measurement error amount) is less than the predetermined value (tolerance value), the process proceeds to step S407. If D is greater than or equal to the predetermined value, the process proceeds to step S405. In step S406, the controller 63 determines D (measurement error amount) as correction information C. In step S406, the controller 63 calculates Os' = Os - Or + C as the measurement result from the optical measuring instrument OM. This means that the measurement result of the first measurement location on the substrate 1 by the optical measuring instrument OM is corrected based on the correction information C, after the calibration was performed based on the measurement result of the reference surface RS by the optical measuring instrument OM. When measuring subsequent shot areas (second measurement locations) of the lot, the controller 63 similarly calculates Os' = Os - Or + C as the measurement result from the optical measuring instrument OM. In step S407, the controller 63 obtains Os' = Os - Or as the measurement result of the height of the shot area.

[0029] Here, as a specific example, let's consider a case where five first measurement points are set in the shot area. Assume that the average Os = 20 nm from the heights of the five first measurement points measured by the optical measuring instrument OM, and that the average As = 50 nm from the heights of the five first measurement points measured by the air sensor 21. Also, assume that the predetermined value (tolerance) is 10 nm. Furthermore, for simplification, assume that Or = 0 and Ar = 0. In this example, the amount of deception D is (50 nm - 0 nm) - (20 nm - 0 nm) = 30 nm. Since D = 30 nm > tolerance (10 nm), the correction information C is 30 nm.

[0030] By determining the correction information for correcting the measurement results by the optical measuring instrument OM as described above, the height of subsequent shot regions and subsequent substrates 1 can be measured quickly and with high accuracy using the optical measuring instrument OM.

[0031] The following describes the measurement deception by the optical measuring instrument OM with reference to Figure 5. The substrate 1 may have multiple layers 52, 53, and 54 on a base material (not shown) made of semiconductor, and may also have a resist 51 that constitutes the outermost surface. At the submicrometer level, the outermost surface of the substrate 1 has irregularities before the resist is applied, and the upper surface of the outermost surface of the substrate 1 (i.e., the resist 51) after the resist 51 is applied also has irregularities.

[0032] In the exposure apparatus EXP, the position of the outermost surface of the resist 51, which is the surface of the substrate 1 that should coincide with the image plane of the projection optical system 3, should be measured by the optical measuring instrument OM. However, in the optical measuring instrument OM, some of the light projected onto the substrate 1 by the light projector 12 may pass through the resist 51 and reach at least one of the multiple layers 52, 53, and 54 beneath the resist 51. Then, light reflected by at least one of the multiple layers 52, 53, and 54 may enter the light receiver 13. Thus, measurement deception can occur because not only the light reflected from the outermost surface of the substrate 1, but also the light reflected from the layer below it enters the light receiver 13. If the multiple layers 52, 53, and 54 were flat and the thickness and refractive index of the resist 51 were known, it might be possible to calculate the amount of measurement deception. However, in reality, neither the multiple layers 52, 53, and 54 nor the surface of the resist 51 are flat, so calculating the amount of measurement deception is not practical.

[0033] (Example 1) Figure 6(a) illustrates the layout of multiple shot regions on substrate 1. In the example in Figure 6(a), the shot region whose height is measured by the air sensor 21 is the shot region 8 located in the center. If the height of all shot regions on substrate 1 were to be measured using the air sensor 21, it would take 300 msec for each measurement point, which is a very long time. The measurement time for one measurement point using the optical measuring instrument OM is, for example, about 10 msec, so measuring with the optical measuring instrument OM significantly increases throughput compared to measuring with the air sensor 21. Therefore, it is desirable to perform measurements without using the air sensor 21 as much as possible.

[0034] Multiple shot regions, each measuring, for example, 26 × 33 mm, may be arranged on the substrate 1. The height distribution is common across the multiple shot regions. Therefore, using the air sensor 21, the heights of multiple measurement points can be measured for only one shot region, and the average of the heights of the multiple measurement points can be calculated. The multiple measurement points can be set to represent the internal structure. For example, 5 × 6 = 30 measurement points can be defined at equal intervals within one shot region, and the heights of these measurement points can be measured using both the air sensor 21 and the optical measuring instrument OM. The air sensor 21 needs to measure the heights of the 30 measurement points sequentially, but the optical measuring instrument OM can measure the heights of all 30 measurement points simultaneously. The air sensor 21 requires 30 × 300 msec = 9000 msec = 9 s to measure the heights of all 30 measurement points, but the optical measuring instrument OM requires only 10 msec because it can measure the heights of all 30 measurement points simultaneously. If we assume that the number of shot areas on substrate 1 is 64, measuring the height of all measurement points with the air sensor 21 would take 9000 msec × 64 = 576000 msec = 576 s = approximately 10 minutes. On the other hand, the optical measuring instrument OM would only take 10 msec × 64 = 640 msec = 0.64 s to measure the height of all measurement points. Note that this calculation does not include the step drive time (tens of msec per step) for stepping the measurement points in the measurement area of ​​the air sensor 21, so measuring the height of all measurement points with the air sensor 21 would take even longer. Also, as the measurement time increases, the air sensor 21 will drift, so if calibration is performed using the reference plane RS every 9 seconds, for example, after measuring the height of 30 measurement points, it would take even longer.

[0035] If we consider an exposure system with a capacity of 300 WPH (7200 sheets per day), it exposes 5 substrates per minute. Therefore, if measurements are taken over a 10-minute period, productivity will be reduced by approximately 50 sheets. For example, if 10 different types of devices are manufactured per day, this would result in a loss of productivity equivalent to 500 sheets per day (a 7% loss). Thus, using the air sensor 21 to measure the height of the entire shot area of ​​the substrate would significantly reduce productivity.

[0036] In this embodiment, after obtaining correction information C using an air sensor and an optical measuring instrument, the height information of the second measurement location can be obtained quickly and with high accuracy by correcting the result of measuring the height of the second measurement location using the optical measuring instrument based on the correction information C.

[0037] It is preferable to measure the height of the first measurement point using an air sensor for every lot (e.g., 25 sheets) to maintain high exposure accuracy. However, after measuring the height of the first measurement point using the air sensor, it is necessary to move the air sensor from the measurement position to the retracted position before performing the exposure operation. To measure the height of the first measurement point again using the air sensor, it is necessary to move the air sensor from the retracted position to the measurement position. Since such operations can reduce productivity, if productivity is a priority, it is acceptable to measure the height of the first measurement point using the air sensor every few lots.

[0038] Furthermore, in order to stabilize the position of the air sensor, a locking mechanism may be provided to fix the position of the air sensor after it has been driven to the measurement position.

[0039] Furthermore, since air sensors are prone to measurement drift, it is desirable to calibrate them periodically. Also, when the type of substrate being processed changes, the internal structure and resist film thickness change, so it is desirable to calibrate the optical measuring instrument using the air sensor. It is desirable to calibrate the optical measuring instrument using the air sensor after each lot, but if the same recipe is repeated, it is acceptable to calibrate the optical measuring instrument using the air sensor every few lots.

[0040] Conventionally, in methods that do not use air sensors, when exposing substrates with different internal structures but the same resist surface height, it was necessary to perform pilot production (test production) to confirm the best focus in order to verify the correct height offset value of the exposure equipment.

[0041] However, by calibrating the optical measuring instrument using an air sensor, accurate height information of the substrate can be obtained using the optical measuring instrument even if the internal structure differs, thus eliminating the need for pilot production. This pilot production requires preparing at least one lot (25 boards) of substrates, exposing and developing them, inspecting the developed substrates with an electron microscope, and calculating the best focus, which takes several hours of adjustment time per recipe. Furthermore, the effort of reworking one lot of substrates is also eliminated.

[0042] (Example 2) In Example 1, throughput was shortened by measuring only one shot area within a single substrate using an air sensor. However, if there is non-uniformity in the resist film thickness across the substrate, for example, measuring only the height of an arbitrary single shot area with an air sensor may result in errors that cannot be ignored. The resist film thickness may also be measured outside the exposure apparatus using a general scanning white light interferometer. Here, we describe a method for correcting the effects of non-uniformity in resist film thickness within the exposure apparatus using an air sensor.

[0043] Consider an example where each shot area measures 26 x 33 mm, and 64 shot areas are arranged on a single substrate. For example, by measuring the height of one measurement point within each shot area using an air sensor, the global height distribution of the substrate surface can be measured. Alternatively, instead of measuring a single point within each shot area, if the resist film thickness distribution of the substrate has already been measured beforehand using a film thickness gauge outside the exposure apparatus, a sparse measurement (measuring only representative points of the in-plane film thickness in this example) can be performed within the exposure apparatus. Figure 6(b) shows a schematic example of sparse measurement. In Figure 6(b), the group of shot areas 9, indicated by the shaded area, can be the target of measurement.

[0044] If one measurement point is measured for each shot area using the air sensor 21, it takes 64 × 300 msec = 19200 msec = 19.2 s. However, if only five selected shot areas are measured, the measurement time can be reduced to 5 × 300 msec = 1500 msec, or 1 / 13th. When the measurement time is long, the air sensor drifts, so calibration using a reference plane is necessary, for example, every 30 measurement points (every 9 s). After measurement using the air sensor is complete, the same measurement point is measured using an optical measuring instrument. As a result, the global height distribution of the substrate surface obtained using the air sensor and the local height information within a single shot area can be compared with the measurement value of the optical measuring instrument that measured the same point. The difference can then be used to correct the measurement value of the optical measuring instrument. If the number of measurement points of the optical measuring instrument does not match the number of measurement points of the air sensor due to sparse sampling, the data can be interpolated between measurement points using approximation methods such as polynomial approximation, thereby comparing it with the measurement results of the optical measuring instrument. This enables highly accurate correction.

[0045] In Example 2, we describe an example with sparsely spaced five characteristic points, but naturally, the sampling locations can be freely changed to measurement points that capture those characteristics, taking into account the pre-existing resist film thickness distribution map and the deformation characteristics of the substrate (unevenness, asymmetric deformation). What is discussed here is that instead of measuring all of the multiple shot areas, the goal is to capture the characteristics of the substrate surface and minimize the number of measurement points, thereby minimizing the use of air sensors and improving throughput.

[0046] Next, a method for manufacturing articles (semiconductor IC elements, liquid crystal display elements, MEMS, etc.) using the aforementioned exposure apparatus will be described. The articles are manufactured by using the aforementioned exposure apparatus to expose a substrate (wafer, glass substrate, etc.) coated with a photosensitive material, developing the substrate (photosensitive material), and processing the developed substrate with other well-known processing steps. Other well-known processes include etching, resist stripping, dicing, bonding, packaging, etc. According to this method for manufacturing articles, it is possible to manufacture articles of higher quality than conventional methods.

[0047] This specification and accompanying drawings describe the following inventions. (Item 1) An optical measuring instrument for measuring the height of the circuit board, An air sensor that measures the height of the substrate based on the pressure in the conduit while discharging air through the conduit, A member having a reference surface, A controller that corrects the result of measuring the height of the second measurement point on the substrate using the optical measuring instrument, based on a first result obtained by measuring the height of the first measurement point on the substrate and the height of the reference surface using the optical measuring instrument, and a second result obtained by measuring the height of the first measurement point on the substrate and the height of the reference surface using the air sensor, A height measuring device characterized by being equipped with the following features. (Item 2) The controller generates correction information to correct the result of measuring the height of the second measurement point on the substrate using the optical measuring instrument, based on the first and second results. A height measuring device as described in item 1, characterized by the above. (Item 3) The controller generates the correction information based on the difference between the first result and the second result. A height measuring device as described in item 2, characterized by the features described herein. (Item 4) The first result is the difference between the result of measuring the height of the first measurement point on the substrate using the optical measuring instrument and the result of measuring the height of the reference surface using the optical measuring instrument. A height measuring device as described in item 3, characterized by the above. (Item 5) The first result is the difference between the average of the heights measured at multiple first measurement points on the substrate using the optical measuring instrument and the height of the reference surface measured using the optical measuring instrument. A height measuring device as described in item 3, characterized by the above. (Item 6) The second result is the difference between the result of measuring the height of the first measurement point on the substrate using the air sensor and the result of measuring the height of the reference surface using the air sensor. A height measuring device as described in item 4, characterized by the features described herein. (Item 7) The second result is the difference between the average of the heights measured at multiple first measurement points on the substrate using the air sensor and the height of the reference surface measured using the air sensor. A height measuring device as described in item 5, characterized by the above. (Item 8) The optical measuring instrument is an oblique incidence measuring instrument that irradiates light onto the surface to be measured and receives the reflected light from the surface to be measured. A height measuring device according to any one of items 1 to 7, characterized by the above. (Item 9) The positioning system further includes a substrate stage for holding the substrate, The aforementioned member is provided on the substrate stage, A height measuring device according to any one of items 1 to 8, characterized by the above. (Item 10) The positioning system includes a measurement system for measuring the position and orientation of the substrate stage, and controls the position and orientation of the substrate stage based on the output of the measurement system. A height measuring device according to item 9, characterized by the features described herein. (Item 11) The controller calibrates the air sensor based on the output of the air sensor when the height of the substrate stage is changed by a predetermined height in the positioning system. A height measuring device as described in item 10, characterized by the features described herein. (Item 12) The aforementioned air sensor is A reference nozzle that discharges air through the first pipeline, A measuring nozzle that discharges air through the second pipeline, A differential pressure sensor that detects the difference between the pressure in the first pipeline and the pressure in the second pipeline, A height measuring device according to any one of items 1 to 11, characterized by including the above. (Item 13) The air sensor further includes a mass flow controller, and air is supplied to the reference nozzle and the measuring nozzle via the mass flow controller. A height measuring device as described in item 12, characterized by the features described herein. (Item 14) The controller updates the correction information when the difference between the first result and the second result is greater than or equal to a predetermined value. A height measuring device according to any one of items 1 to 13, characterized by the above. (Item 15) The predetermined value is 10 nm. A height measuring device as described in item 14, characterized by the features described herein. (Item 16) An exposure apparatus for projecting a pattern from an original plate onto a substrate using a projection optical system and exposing the substrate, A positioning system including a substrate stage for holding the substrate, A height measuring device according to any one of items 1 to 15, configured to measure the height of the substrate held by the substrate stage, An exposure apparatus characterized by comprising: (Item 17) The first result is the difference between the average of the heights of multiple first measurement points within the shot area of ​​the substrate measured using the optical measuring instrument and the height of the reference surface measured using the optical measuring instrument. The second result is the difference between the average of the heights of the plurality of first measurement points within the shot area of ​​the substrate measured using the air sensor and the height of the reference surface measured using the air sensor. The exposure apparatus according to item 16, characterized by the features described herein. (Item 18) The optical measuring instrument is an oblique incidence measuring instrument that irradiates light onto the surface to be measured and receives the reflected light from the surface to be measured. An exposure apparatus according to item 16 or 17, characterized by the features described herein. (Item 19) The positioning system includes a measurement system for measuring the position and orientation of the substrate stage, and controls the position and orientation of the substrate stage based on the output of the measurement system. An exposure apparatus according to any one of items 16 to 18, characterized by the features described herein. (Item 20) The controller calibrates the air sensor based on the output of the air sensor when the height of the substrate stage is changed by a predetermined height in the positioning system. The exposure apparatus according to item 19, characterized by the features described herein. (Item 21) An exposure step in which a substrate is exposed using an exposure apparatus described in any one of items 16 to 20, A developing step for developing the substrate after the exposure step, A processing step to obtain an article by processing the substrate that has undergone the development step, A method for manufacturing articles, characterized by including the following: (others) The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0048] 1: Substrate, 2: Reference plate (component), 21: Air sensor, OM: Optical measuring instrument, 63: Controller, RS: Reference plane, HM: Height measuring device

Claims

1. An optical measuring instrument for measuring the height of the circuit board, An air sensor that measures the height of the substrate based on the pressure in the conduit while discharging air through the conduit, A member having a reference surface, A controller that corrects the result of measuring the height of the second measurement point on the substrate using the optical measuring instrument, based on a first result obtained by measuring the height of the first measurement point on the substrate and the height of the reference surface using the optical measuring instrument, and a second result obtained by measuring the height of the first measurement point on the substrate and the height of the reference surface using the air sensor, A height measuring device characterized by being equipped with the following features.

2. The controller generates correction information to correct the result of measuring the height of the second measurement point on the substrate using the optical measuring instrument, based on the first and second results. The height measuring device according to feature 1.

3. The controller generates the correction information based on the difference between the first result and the second result. The height measuring device according to claim 2.

4. The first result is the difference between the result of measuring the height of the first measurement point on the substrate using the optical measuring instrument and the result of measuring the height of the reference surface using the optical measuring instrument. The height measuring device according to feature 3.

5. The first result is the difference between the average of the heights measured at multiple first measurement points on the substrate using the optical measuring instrument and the height of the reference surface measured using the optical measuring instrument. The height measuring device according to feature 3.

6. The second result is the difference between the result of measuring the height of the first measurement point on the substrate using the air sensor and the result of measuring the height of the reference surface using the air sensor. The height measuring device according to feature 4.

7. The second result is the difference between the average of the heights measured at multiple first measurement points on the substrate using the air sensor and the height of the reference surface measured using the air sensor. The height measuring device according to claim 5.

8. The optical measuring instrument is an oblique incidence measuring instrument that irradiates light onto the surface to be measured and receives the reflected light from the surface to be measured. The height measuring device according to feature 1.

9. The positioning system further includes a substrate stage for holding the substrate, The aforementioned member is provided on the substrate stage, The height measuring device according to feature 1.

10. The positioning system includes a measurement system for measuring the position and orientation of the substrate stage, and controls the position and orientation of the substrate stage based on the output of the measurement system. The height measuring device according to feature 9.

11. The controller calibrates the air sensor based on the output of the air sensor when the height of the substrate stage is changed by a predetermined height in the positioning system. The height measuring device according to claim 10.

12. The aforementioned air sensor is A reference nozzle that discharges air through the first pipeline, A measuring nozzle that discharges air through the second pipeline, A differential pressure sensor that detects the difference between the pressure in the first pipeline and the pressure in the second pipeline, The height measuring device according to claim 1, characterized by including the following:

13. The air sensor further includes a mass flow controller, and air is supplied to the reference nozzle and the measuring nozzle via the mass flow controller. The height measuring device according to claim 12.

14. The controller updates the correction information when the difference between the first result and the second result is greater than or equal to a predetermined value. The height measuring device according to claim 2.

15. The predetermined value is 10 nm. The height measuring device according to feature 14.

16. An exposure apparatus for projecting a pattern from an original plate onto a substrate using a projection optical system and exposing the substrate, A positioning system including a substrate stage for holding the substrate, A height measuring device according to any one of claims 1 to 15, configured to measure the height of the substrate held by the substrate stage, An exposure apparatus characterized by comprising:

17. The first result is the difference between the average of the heights of multiple first measurement points within the shot area of ​​the substrate measured using the optical measuring instrument and the height of the reference surface measured using the optical measuring instrument. The second result is the difference between the average of the heights of the plurality of first measurement points within the shot region of the substrate measured using the air sensor and the height of the reference surface measured using the air sensor. The exposure apparatus according to claim 16.

18. The optical measuring instrument is an oblique incidence measuring instrument that irradiates light onto the surface to be measured and receives the reflected light from the surface to be measured. The exposure apparatus according to claim 16.

19. The positioning system includes a measurement system for measuring the position and orientation of the substrate stage, and controls the position and orientation of the substrate stage based on the output of the measurement system. The exposure apparatus according to claim 16.

20. The controller calibrates the air sensor based on the output of the air sensor when the height of the substrate stage is changed by a predetermined height in the positioning system. The exposure apparatus according to feature 19.

21. An exposure step of exposing a substrate with the exposure apparatus described in claim 16, A developing step for developing the substrate after the exposure step, A processing step to obtain an article by processing the substrate that has undergone the development step, A method for manufacturing articles, characterized by including the following:

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