JP2016075659A - Curvature measurement device and curvature measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curvature measurement device and curvature measurement method that can attain suppression of curvature unmeasurability and improvement in curvature measurement accuracy.SOLUTION: A curvature measurement device 10 comprises: a laser beam emitting part 21 that emits laser beam; a first polarization beam slitter 22 that splits the emitted laser beam into first laser beam L1 and second laser beam L2 respectively having different polarization directions and traveling directions; a mirror 23 that reflects the first laser beam L1 so that the first laser beam L1 and the second laser beam L2 travel in parallel to an object under measurement, namely a substrate W; a second polarization beam splitter 10d that transmits the laser beam L2 specularly reflected upon the substrate W, and reflects the laser beam L1 specularly reflected upon the substrate W in a direction different from the laser beam L2; a one-dimensional first position detection element 10e that detects an incident position of the reflected first laser beam L1; and a one-dimensional second position detection element 10f that detects an incident position of the reflected second laser beam L2.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a curvature measuring device and a curvature measuring method.

  Conventionally, in a manufacturing process of a semiconductor element that requires a relatively large crystal film like a power device such as an IGBT (Insulated Gate Bipolar Transistor), a single crystal is formed on a substrate such as a semiconductor wafer. An epitaxial growth technique is used in which a thin film is vapor-phase grown to form a film. In a film forming apparatus used for this epitaxial growth technique, a substrate such as a wafer is placed in a film forming chamber maintained at normal pressure or reduced pressure. Then, while the substrate is heated, a gas (raw material gas) serving as a raw material for film formation is supplied into the film formation chamber. As a result, a chemical reaction such as a thermal decomposition reaction or a hydrogen reduction reaction of the source gas occurs on the surface of the substrate, and an epitaxial film is formed on the substrate.

  In this film forming apparatus, a curvature measuring apparatus (warp measuring apparatus) that measures the curvature of a substrate as a measurement object is used. This curvature measuring device is mainly used when optimizing a process procedure, but in recent years, it is also used in a mass production device, and constant warpage monitoring has been required. For example, in the film formation of gallium nitride (GaN) on 8 inch silicon, in addition to the difference in thermal expansion coefficient between silicon and GaN thin film and the large mismatch of the crystal lattice constant, there are film preparation conditions that go back and forth over a large temperature range, It is very important to monitor how much the wafer is warped during film formation. If this warpage monitoring is neglected, the temperature of the product is lowered during film formation or after the film formation is lowered, and this leads to deterioration of product quality due to the tearing of the wafer and the generation of fine cracks (cracks) in the thin film. Accordingly, warpage monitoring is essential for optimizing process procedures prior to mass production, but is also necessary for maintaining quality even in mass production situations where the conditions in the film forming chamber change little by little.

  At present, the mainstream curvature measuring apparatus makes two or more laser beams parallel to be incident on the substrate through the window of the film forming chamber, reflected by the substrate, and returned through the window. The position of the laser beam is detected and the interval between them is read. Even when three or more laser beams are used, there is no difference in principle from the case where two laser beams are used. For the sake of simplicity, the case where two laser beams are used will be described below. As a method for detecting two laser beams, a two-point collective CCD method in which two laser beams are collectively detected by a two-dimensional CCD (charge coupled device) is generally employed. In this method, two laser beams are incident on the same element surface (light receiving surface), and these laser beams are obtained as two points in the pixel. Then, the distance between the two points is calculated by image processing and converted into a curvature.

JP-A-10-78310

  However, in the above-described two-point collective CCD system, if the warp is large, the two points may coincide with each other, and the distance between the two points may not exist. This makes it impossible to measure the curvature even though the curvature itself exists. Even if the two points do not match, the SN ratio (S / N) is deteriorated in a region where warpage is large due to the CCD resolution. Furthermore, in order to reduce the window through which the two laser beams pass, when it is necessary to narrow between the two points, the conditions become worse, and the SN ratio becomes worse.

  The problem to be solved by the present invention is to provide a curvature measuring device and a curvature measuring method capable of preventing the inability to measure the curvature and improving the accuracy of the curvature measurement.

  A first curvature measurement apparatus according to an embodiment of the present invention includes a light emitting unit that emits laser light, and a laser beam emitted from the light emitting unit, and a first laser beam having a different polarization direction and traveling direction. A first polarization beam splitter that separates the second laser beam, and the first laser beam and the second laser beam so that the first laser beam and the second laser beam travel to the object to be measured in parallel. The reflecting part that reflects either one of the first laser light and the second laser light that is specularly reflected by the object to be measured is transmitted, and the other is reflected in a direction different from the one traveling direction. A second polarizing beam splitter; a one-dimensional first position detecting element that detects an incident position of the first laser beam reflected by the second polarizing beam splitter or transmitted through the second polarizing beam splitter; Second polarization And a second position detecting element of the one-dimensional detecting the incident position of the second laser beam reflected by the over beam splitter has passed through the or a second polarizing beam splitter.

  In addition, the second curvature measuring apparatus according to the embodiment of the present invention includes a light emitting unit that emits laser light and a laser beam emitted from the light emitting unit that has a polarization direction and a traveling direction that are different from each other. A first polarization beam splitter that separates the light and the second laser light, and a reflection unit that reflects the second laser light so that the first laser light and the second laser light travel in parallel to the measurement object A second polarization beam splitter that transmits one of the first laser beam and the second laser beam traveling toward the measurement object, and the first laser beam and the second laser beam traveling toward the measurement object A quarter-wave plate through which the first laser beam and the second laser beam that have been specularly reflected by the measurement object pass, and a quarter-wave plate that is specularly reflected by the measurement object. The first laser beam and the second laser beam that have passed And a first position detecting element and a second position detecting element for detecting the individual position of incidence of the light, respectively.

  In the second curvature measuring apparatus, when the first laser light traveling toward the measurement object passes through the second polarization beam splitter, the second polarization beam splitter is specularly reflected by the measurement object. The first laser beam that has passed through the quarter-wave plate is reflected, and the reflection unit reflects the second laser beam that has been specularly reflected by the measurement object and passed through the quarter-wave plate, The position detection element detects the incident position of the first laser beam reflected by the second polarization beam splitter, and the second position detection element determines the incident position of the second laser beam reflected by the reflection unit. It is desirable to detect.

  In the second curvature measuring apparatus, when the second laser beam traveling toward the measurement object passes through the second polarization beam splitter, the first polarization beam splitter is specularly reflected by the measurement object. The first laser beam that has passed through the quarter-wave plate is reflected, and the second polarizing beam splitter reflects the second laser beam that has been specularly reflected by the measurement object and passed through the quarter-wave plate. The first position detecting element detects the incident position of the first laser beam reflected by the first polarizing beam splitter, and the second position detecting element is the first position reflected by the second polarizing beam splitter. It is desirable to detect the incident position of the second laser beam.

  Further, in the first or second curvature measuring device, the displacement amount of the incident position of the first laser beam detected by the first position detecting element and the second amount detected by the second position detecting element. The difference between the amount of displacement of the incident position of the laser beam is calculated, and the amount of curvature change of the measurement object is calculated from the correlation between the calculated difference and the respective optical path lengths of the first laser beam and the second laser beam. It is desirable to further include a calculation unit.

  In the first or second curvature measuring apparatus, the first position detecting element and the second position detecting element are two lines of the first laser beam and the second laser beam reflected by the measurement object. It is desirable to detect the shortest distance displacement in minutes.

  In the first or second curvature measuring apparatus, the first laser beam is condensed in a direction perpendicular to the element array direction of the first position detection element, and the second laser beam is detected in the second position. It is desirable to further include a condensing lens that collects light in a direction perpendicular to the element row direction of the elements.

  In the first or second curvature measuring apparatus, the light emitting unit desirably emits laser light having a wavelength of 700 nm or less as laser light.

  In the first or second curvature measuring apparatus, the first position detection element has a first light receiving surface on which the first laser light is incident, and the first light receiving surface is a method of the first light receiving surface. The linear direction is inclined at least 10 degrees from the optical axis of the first laser beam, and the second position detecting element has a second light receiving surface on which the second laser beam is incident, It is desirable that the normal direction of the surface is inclined at least 10 degrees from the optical axis of the second laser beam.

  In the first or second curvature measuring apparatus, the first laser beam is stretched in a direction perpendicular to the element array direction of the first position detection element, and the second laser beam is extended to the second position detection element. It is desirable to further include a molding portion that extends in a direction perpendicular to the element array direction.

  In the first curvature measuring method according to the embodiment of the present invention, the step of emitting laser light from the light emitting unit and the laser beam emitted from the light emitting unit are different in polarization direction and traveling direction, respectively. A step of separating the first laser beam and the second laser beam by the first polarization beam splitter, and the first laser beam and the second laser beam so that the first laser beam and the second laser beam proceed to the measurement object in parallel. A step of reflecting either one of the second laser beams by the reflecting section, and transmitting one of the first laser beam and the second laser beam specularly reflected by the measurement object, and passing the other one of the second laser beams The step of reflecting by the second polarizing beam splitter in a direction different from the traveling direction, and the incident position of the first laser beam reflected by the second polarizing beam splitter or transmitted through the second polarizing beam splitter. A step of detecting by the original first position detecting element, and an incident position of the second laser light transmitted through the second polarizing beam splitter or reflected by the second polarizing beam splitter; And detecting with a detection element.

  In the second curvature measurement method according to the embodiment of the present invention, the step of emitting laser light from the light emitting unit and the laser beam emitted from the light emitting unit are different in polarization direction and traveling direction, respectively. A step of separating the first laser beam and the second laser beam by the first polarization beam splitter, and the second laser beam so that the first laser beam and the second laser beam proceed to the measurement object in parallel. A step of reflecting by the reflection unit, a step of transmitting one of the first laser beam and the second laser beam traveling toward the measurement object by the second polarization beam splitter, and the progression toward the measurement object Passing the first laser light and the second laser light through the quarter-wave plate, and passing the first laser light and the second laser light, which are specularly reflected by the measurement object, through the quarter-wave plate; Specular reflection by the measurement object And a step of detecting by a first laser beam and the second laser beam of each of the incident positions, respectively a first position detecting element and a second position detecting element passed through the quarter-wave plate Te.

  In the second curvature measurement method, when the first laser beam traveling toward the measurement object passes through the second polarization beam splitter, it is specularly reflected by the measurement object and passes through the quarter wavelength plate. The first laser beam is reflected by the second polarizing beam splitter and detected by the first position detecting element, and the second laser beam reflected by the measurement object and reflected by the quarter-wave plate is reflected. It is desirable that the light is reflected by the portion and detected by the second position detecting element.

  In the second curvature measurement method, when the second laser beam traveling toward the measurement object passes through the second polarization beam splitter, it is specularly reflected by the measurement object and passes through the quarter wavelength plate. The first laser beam reflected is reflected by the first polarization beam splitter and detected by the first position detecting element, and the second laser beam reflected by the measurement object and passed through the quarter-wave plate is reflected by the first laser beam. Preferably, the light is reflected by the second polarization beam splitter and detected by the second position detection element.

  According to one aspect of the present invention, it is possible to achieve inhibition of curvature measurement impossibility and improvement in curvature measurement accuracy.

It is a figure which shows schematic structure of the film-forming apparatus which concerns on 1st Embodiment. It is a front view showing a schematic structure of a curvature measuring device concerning a 1st embodiment. It is a front view which shows the modification 1 of the curvature measuring apparatus which concerns on 1st Embodiment. It is a side view showing a schematic structure of a curvature measuring device concerning a 1st embodiment. It is explanatory drawing for demonstrating the laser beam space | interval on the board | substrate surface which concerns on 1st Embodiment. It is a graph which shows the relationship between the incident angle and reflectance of S polarized light and P polarized light which concern on 1st Embodiment. It is a front view which shows schematic structure of the curvature measuring apparatus which concerns on 2nd Embodiment. It is a front view which shows schematic structure of the curvature measuring apparatus which concerns on 3rd Embodiment. It is a front view which shows the modification of the curvature measuring apparatus which concerns on 3rd Embodiment. It is a front view which shows the modification 2 of the curvature measuring apparatus which concerns on 1st Embodiment. It is a perspective view which shows the curvature measuring apparatus shown in FIG. It is a perspective view which shows the modification of the curvature measuring apparatus shown in FIG.

(First embodiment)
A first embodiment will be described with reference to FIGS.

  As shown in FIG. 1, a film forming apparatus 1 according to the first embodiment includes a chamber 2 serving as a film forming chamber for forming a film on a substrate W, and a gas (raw material gas) for the substrate W in the chamber 2. A gas supply unit 3 for supplying the substrate W, a shower plate 4 positioned at the top of the chamber 2, a susceptor 5 for supporting the substrate W in the chamber 2, a rotating unit 6 for rotating while holding the susceptor 5, and a substrate W , A plurality of gas discharge portions 8 for discharging the gas in the chamber 2, an exhaust mechanism 9 for exhausting gas from these gas discharge portions 8, and the curvature (warping amount) of the substrate W. The curvature measuring device 10, the control part 11 which controls each part, and the alerting | reporting part 12 which alert | reports a warning are provided.

  The chamber 2 functions as a film formation chamber (reaction chamber) in which a thin film is grown on the surface of a substrate W (for example, a wafer which is a semiconductor substrate) to form an epitaxial film. The chamber 2 is formed in a box shape such as a cylindrical shape, and accommodates a substrate W or the like serving as a processing target portion therein.

  The gas supply unit 3 includes a plurality of gas storage units 3a that individually store gases, a plurality of gas pipes 3b that connect the gas storage units 3a and the shower plate 4, and a gas that flows through the gas pipes 3b. And a plurality of gas valves 3c for changing the flow rate. These gas valves 3c are individually provided in each gas pipe 3b, are electrically connected to the control unit 11, and their driving is controlled by the control unit.

  The gas supply unit 3 supplies a raw material gas for growing a crystal film on the surface of the substrate W heated by the heater 7, for example, three kinds of gases into the chamber 2 through the shower plate 4. For example, when a Si substrate is used as the substrate W and a GaN (gallium nitride) epitaxial film is formed by metal organic chemical vapor deposition (MOCVD), gallium (TMG) gas such as trimethyl gallium (TMG) gas is used as an example. A source gas of Ga), a source gas of nitrogen (N) such as ammonia (NH 3), or a hydrogen gas as a carrier gas is used.

  These three kinds of gases are respectively stored in the gas storage portions 3a, and these gases are supplied as a raw material gas in a shower shape from the shower plate 4 toward the substrate W, and a GaN epitaxial film is formed on the substrate W. Will be formed. The type of gas and the number of types thereof are not particularly limited. For example, when a silicon nitride (SiC) epitaxial film is formed on the substrate W, the first, second, and third types are used. It is possible to use a source gas of carbon, a source gas of silicon, a gas used for separating these gases, and a separation gas having poor reactivity with the other two types of gases. is there.

  The shower plate 4 is provided in the upper part of the chamber 2 and is formed in a plate shape having a predetermined thickness. The shower plate 4 has a large number of gas supply passages 4a through which gas flows and gas discharge holes (gas discharge holes) 4b connected to the gas supply passages 4a. These gas supply flow paths 4a and gas discharge holes 4b are formed on the substrate W in a state in which the gases are separated without mixing a plurality of types (for example, first, second, and third types) of gases. It is formed in a structure that enables spraying in a shower shape. For example, the gas supply channels 4a are independent from each other, and the gases are prevented from being mixed and reacting with each other in the shower plate 4. In the shower plate 4, the gases are not necessarily supplied separately, but may be supplied in a mixed manner.

  The shower plate 4 rectifies the gas for forming the epitaxial film and supplies the gas in a shower shape from the gas discharge holes 4 b toward the surface of the substrate W. As a material of the shower plate 4, for example, a metal material such as stainless steel or aluminum alloy can be used. By using such a shower plate 4, the flow of the source gas in the chamber 2 can be made uniform, and the source gas can be uniformly supplied onto the substrate W.

  The susceptor 5 is provided in the upper part of the rotation part 6, and is formed in the cyclic | annular shape which has the opening part 5a. The susceptor 5 is provided with a counterbore (annular recess) on the inner peripheral side of the opening 5a, and has a structure for receiving and supporting the outer peripheral portion of the substrate W in the counterbore. Since the susceptor 5 is exposed to high temperatures, for example, the surface of a carbon (C) material such as isotropic graphite is coated with high-heat-resistant high-purity SiC by a CVD method. The structure of the susceptor 5 uses the structure in which the opening 5a is left as described above, but is not limited to this. For example, a member that closes the opening 5a is provided, and the opening 5a is formed. It is also possible to use a closing structure.

  The rotating portion 6 includes a cylindrical portion 6a that holds the susceptor 5, and a hollow rotating body 6b that serves as a rotating shaft of the cylindrical portion 6a. The cylindrical portion 6a has a structure in which an upper portion is opened, and the susceptor 5 is disposed on the upper portion of the cylindrical portion 6a. By placing the substrate W on the susceptor 5, the opening 5 a of the susceptor 5 is covered and a hollow region is formed. In the rotating part 6, the susceptor 5 rotates through the cylindrical part 6a when the rotating body 6b is rotated by a rotating mechanism (not shown). For this reason, the substrate W on the susceptor 5 rotates with the rotation of the susceptor 5.

  Here, the space region in the chamber 2 is the first region R1, and the hollow region substantially separated from the first region R1 by the substrate W and the susceptor 5 is the second region R2. Since the first region R1 and the second region R2 are separated from each other, it is possible to prevent the surface of the substrate W from being contaminated by the contaminant generated around the heater 7. It is also possible to prevent the gas in the first region R1 from entering the second region R2 and coming into contact with the heater 7 disposed in the second region R2.

  The heater 7 is provided in the cylindrical portion 6a, that is, in the second region R2. As the heater 7, for example, a resistance heater can be used, and the heater is configured by coating a surface of a carbon (C) material such as isotropic graphite with high heat-resistant SiC. The heater 7 is fed by a wiring 7a passing through the inside of a substantially cylindrical quartz shaft 6c provided in the rotating body 6b, and heats the substrate W from its back surface. The wiring 7 a is electrically connected to the control unit 11, and power supply to the heater 7 is controlled by the control unit 11.

  In addition, an elevating pin, an elevating device (none of which are shown), etc., are arranged as a substrate elevating mechanism inside the shaft 6c. The elevating device can raise or lower the elevating pins, and the elevating pins are used when carrying the substrate W into the chamber 2 and carrying it out of the chamber 2. The lifting pins support and lift the substrate W from below and pull it away from the susceptor 5. Then, the substrate W is placed at a predetermined position above the susceptor 5 on the rotating unit 6 so that the substrate W can be transferred to and from a robot (not shown) for transporting the substrate W. To do.

  The gas discharge section 8 is a discharge hole for discharging the raw material gas after the reaction, and a plurality of gas discharge sections 8 are provided in the lower portion of the chamber 2. These gas discharge portions 8 are provided on the bottom surface of the chamber 2 and positioned around the rotation portion 6, and are connected to an exhaust mechanism 9 that exhausts gas.

  The exhaust mechanism 9 includes a plurality of gas exhaust passages 9a through which the raw material gas after reaction flows, an exhaust valve 9b that changes the flow rate of the gas, and a vacuum pump 9c that serves as an exhaust drive source. The exhaust mechanism 9 exhausts the raw material gas after the reaction from the inside of the chamber 2 through each gas discharge unit 8. The exhaust valve 9 b and the vacuum pump 9 c are electrically connected to the control unit 11, and the driving thereof is controlled by the control unit 11. The exhaust mechanism 9 can adjust the inside of the chamber 2 to a predetermined pressure according to the control of the control unit 11.

  The curvature measuring device 10 is provided on the upper portion of the shower plate 4 and measures the curvature of the substrate W on the susceptor 5 by projecting and receiving two laser beams on the substrate W on the susceptor 5 (specifically, , Described later). Each laser beam is projected and received through a light-transmitting portion located between the gas supply channels 4 a of the shower plate 4, that is, through a window (laser beam passage window) of the chamber 2. The curvature measuring apparatus 10 is electrically connected to the control unit 11 and passes the measured curvature (curvature information) to the control unit 11.

  As the shape of the window of the chamber 2, various shapes such as a slit shape, a rectangular shape, and a circular shape can be used, and the size of the window is a size capable of projecting and receiving laser light. It is. As the window material, for example, a light-transmitting material such as quartz glass can be used.

  The control unit 11 includes a microcomputer that centrally controls each unit, and a storage unit that stores film formation processing information related to film formation processing, various programs, and the like (none of which are shown). The control unit 11 controls the rotation mechanism of the gas supply unit 3 and the rotation unit 6, the exhaust mechanism 9, and the like based on the film formation processing information and various programs, and rotates according to the rotation of the rotation unit 6. Control of gas supply for supplying various gases from the gas supply unit 3 via the shower plate 4 and heating of the substrate W by the heater 7 is performed on the surface of the substrate W on 5. In the control of the gas supply unit 3, the operation of each gas valve 3c of the gas supply unit 3 is controlled to adjust three types of gas supply, for example, the timing and period of supplying each of the three types of gas. Is possible.

  Further, the control unit 11 determines whether the curvature measured by the curvature measuring device 10 has reached a predetermined set value, and determines that the curvature measured by the curvature measuring device 10 has reached a predetermined set value. The film processing is stopped, and a notification instruction is output to the notification unit 12. The set value is set in advance by a user or the like via an input unit (for example, an input device such as a keyboard or a mouse), and can be changed as necessary.

  When the notification unit 12 receives a notification instruction from the control unit 11, that is, when the curvature measured by the curvature measuring apparatus 10 reaches a predetermined set value, there is a problem with the warp of the substrate W to the user (warning). ). As this alerting | reporting part 12, it is possible to use various alerting | reporting parts, such as alarm devices, such as a lamp | ramp and a buzzer, the display part which displays a character, and the audio | voice output part which outputs an audio | voice.

  The film forming apparatus 1 having such a configuration rotates the substrate W by the rotation of the rotating unit 6 and heats the substrate W by the heater 7. Further, three kinds of source gases are introduced into the chamber 2 by the shower plate 4, the three kinds of source gases are respectively supplied in a shower shape toward the surface of the substrate W, and an epitaxial film is vapor-phased on the substrate W such as a wafer. Grow to form a film. The shower plate 4 supplies the three kinds of gases to the substrate W in the chamber 2 without being mixed, without mixing them. In the film forming apparatus 1, a plurality of types of gases, for example, the first, second, and third types of gases are used to form the epitaxial film, but the types of gases are limited to three. For example, it may be two types or more than three types.

  It is possible to carry the substrate W into the chamber 2 or carry the substrate W out of the chamber 2 using a transfer robot (not shown). In this case, it is possible to use the above-described substrate lifting mechanism. For example, when the substrate W is unloaded, the substrate W is lifted by the substrate lifting mechanism and pulled away from the susceptor 5. Next, the substrate W is delivered to the transfer robot and is carried out of the chamber 2. When the substrate W is carried in, the substrate W is received from the transfer robot, the substrate W is lowered by the substrate lifting mechanism, and the substrate W is placed on the susceptor 5.

  Next, the curvature measuring apparatus 10 will be described in detail with reference to FIGS. 2 to 4 show schematic structures of the curvature measuring apparatus 10 using schematic diagrams of optical components. Although the distance between the curvature measuring apparatus 10 and the substrate W is shown short, Is a distance of about 20 to 50 cm, and the laser beam passes through the window of the chamber 2. Although the direction of the laser beam reflected by the polarizing beam splitter is shown to be bent at a substantially right angle, this angle does not need to be in the vicinity of a right angle in some cases.

  As shown in FIG. 2, the curvature measuring apparatus 10 includes an irradiation unit 10 a that allows two laser beams L 1 and L 2 to enter the substrate W of the measurement target in parallel, and two laser beams L 1 and L 2. An optical filter 10b that cuts light other than the wavelength, a condensing lens 10c that condenses the two laser lights L1 and L2, and a path change that separates the two laser lights L1 and L2 specularly reflected by the substrate W. 10d, one-dimensional first position detecting element 10e for detecting the incident position of the first laser beam L1 out of the two separated laser beams L1 and L2, and the two separated laser beams L1 And L2, the one-dimensional second position detection element 10f for detecting the incident position of the second laser beam L2, and the first position detection element 10e and the second position detection element 10f detected by the first position detection element 10f. Laser light L1 and And a calculation unit 10g for calculating the curvature of the substrate W (the warp amount) using the second incident position.

  The irradiation unit 10a causes the first laser light L1 and the second laser light L2 having different polarization directions, that is, different polarization components (polarization planes), to enter the substrate W in a parallel state. For example, the irradiation unit 10 a includes a laser light emitting unit (light emitting unit) 21 that emits laser light, a polarizing beam splitter (first polarizing beam splitter) 22, and a mirror (reflecting unit) 23. The irradiating unit 10a separates the laser light emitted from the laser light emitting unit 21 into an S-polarized component (S-polarized light) and a P-polarized component (P-polarized light) by the polarization beam splitter 22, and the laser light of the S-polarized component (first polarization). 1 laser beam L1) is incident on the substrate W as it is, and the P-polarized component laser beam (second laser beam L2) is reflected by the mirror 23 so as to be parallel to the S-polarized component laser beam. To enter. The traveling directions of the laser beams L1 and L2 do not necessarily have to be strictly parallel. Thus, as the polarization component (polarization direction), for example, there are an S-polarization component and a P-polarization component perpendicular to the traveling direction of light, and these S-polarization component and P-polarization component are components orthogonal to each other. At this time, the polarization components (polarization directions) are not necessarily orthogonal, but are preferably 70 degrees or more and 90 degrees or less in order to separate them with higher accuracy.

  Here, the polarization beam splitter is an optical component formed by bonding two prisms on one joint surface. A multilayer film made of a dielectric is formed on the joint surface in advance, so that it can be joined according to the polarization direction. The function of transmitting or reflecting light on the surface is given. By appropriately designing the structure of the multilayer film formed on the bonding surface, it has a function of reflecting P-polarized light and transmitting S-polarized light on the bonding surface, or conversely reflecting S-polarized light and transmitting P-polarized light on the bonding surface. Functional ones can be made. For the sake of simplicity, the former polarization beam splitter will be referred to as a P polarization reflection type or S polarization transmission type, and the latter polarization beam splitter will be referred to as an S polarization reflection type or P polarization transmission type. These polarizing beam splitters having different functions have their own characteristics and can be used appropriately. The polarization beam splitter 22 for separating the laser beam of FIG. 2 into two is an S-polarized transmission type, and a polarization beam for separating the two laser beams reflected from the measurement object (substrate W) by polarization. The splitter (the course changing unit 10d) is an S-polarized reflection type. FIG. 3 shows a case where the present embodiment having the configuration of FIG. 2 is configured using only a P-polarized transmission type polarization beam splitter. Regarding the S-polarized transmission type polarization beam splitter, reference documents include “WO9707418 (WO / 1997/007418)” or “Li Li and JA Dobrowolski,“ High-performance thin-film polarizing beam splitter operating at angles greater ”. than the critical angle ", Applied Optics, Vol. 39, No. 16, pp. 2754-71.

  The incident positions of the laser beams L1 and L2 with respect to the substrate W are, for example, near the center of the substrate W, and the incident angle A1 is preferably at least 20 degrees or less (details will be described later). Further, the laser light avoids the influence from the light emission of the red-hot substrate W, for example, a wavelength of 700 nm or less, more preferably 600 nm or less (for example, 532 nm) having a high sensitivity of the silicon detection system and a small influence of thermal radiation. It is desirable to use the laser beam.

  The optical filter 10b is provided on the optical path between the substrate W and the path changing unit 10d and in which the first laser light L1 and the second laser light L2 travel in parallel. Lights other than the wavelengths of the laser light L1 and the second laser light L2 are cut (removed). As the optical filter 10b, for example, a monochromatic filter can be used. By providing the optical filter 10b, light having a wavelength other than the laser beams L1 and L2 (in the above example, green) is prevented from entering the position detection elements 10e and 10f. The position detection accuracy can be improved by avoiding the influence of the light emission.

  As the one-dimensional position detecting element 10e or 10f, for example, a semiconductor position detecting element (PSD) is used. The PSD obtains the center of gravity (position) of the distribution of incident laser light (the amount of light at the spot), and outputs the center of gravity as two electrical signals (analog signals). PSD is sensitive to light in the visible light range. In the film forming apparatus 1, the substrate W is red hot, that is, emits red light. If the substrate W only heats up red, the intensity of the laser beam is overwhelmingly strong, so that there is no problem if at least a green laser beam separated from red is used. However, when the film is formed in the film forming apparatus 1, there is a timing at which the laser light is hardly reflected due to the interference between the film and the laser light. At this timing, since the intensity of red light exceeds the intensity of the reflected laser beam, the position of the laser beam reflected from the measurement object (substrate W) on the position detection element 10e or 10f is accurately or It may become impossible to measure at all. In order to suppress this, it is desirable to provide an optical filter 10b that does not transmit light other than the wavelength of the laser light used in this embodiment. As the position detection element 10e or 10f, a solid-state imaging element (CCD, CMOS, etc.) can be used in addition to PSD.

  Further, in order to eliminate the effect of interference caused by the film formed on the measurement object, it is also effective to use a laser beam having a wavelength that can be absorbed by the film to be formed as the laser light of this embodiment. . More specifically, laser light having higher energy than the band gap of a film to be formed can be given. When the film to be formed absorbs the laser light used in the present embodiment, the interference effect decreases as the film becomes thicker, and the interference effect does not appear at a certain thickness. For example, when GaN is formed, GaN has an absorption edge in the ultraviolet region (365 nm) at room temperature, but at a temperature of 700 ° C. or higher, the band gap becomes small and absorbs light in the blue-violet region. Therefore, when GaN is grown at a temperature of 700 ° C. or higher, the effect of GaN interference can be reduced by using, for example, 405 nm laser light in this embodiment.

  The condensing lens 10c is provided on the optical path between the substrate W and the path changing unit 10d and in which the first laser light L1 and the second laser light L2 travel in parallel. The condensing lens 10c emits the first laser light L1 in a direction (short direction) perpendicular to the element array direction of the first position detecting element 10e on the element surface (light receiving surface) of the first position detecting element 10e. Condensing and condensing the second laser light L2 on the element surface (light receiving surface) of the second position detecting element 10f in a direction (short direction) perpendicular to the element array direction of the second position detecting element 10f. . A semi-cylindrical lens can be used as the condenser lens 10c.

  Here, as shown in FIG. 4 (side view of FIG. 2), when the substrate W is tilted due to vibration or the like, the second laser light L2 reflected by the substrate W starts from the point (incident point) incident on the substrate W. It swings like a fan. Although not shown in FIG. 4 for simplification of the drawing, the first laser beam L1 is similarly fan-shaped. For this reason, the second laser beam L2 reflected by the substrate W is added to the second position so that the first laser beam L1 reflected by the substrate W does not deviate from the first position detection element 10e. In order to collect light so as not to deviate from the position detection element 10f, an appropriate lens is installed as the condenser lens 10c. As a result, the first laser beam L1 and the second laser beam L2 that have been fan-shaped due to the tilt of the substrate W can be collected again at one point. At this time, if a simple circular lens is used, even displacement information due to the warp of the substrate W may be lost. Therefore, a semi-cylindrical lens is used as the condensing lens 10c so that the optical displacement in the warp information direction, that is, the longitudinal direction of each of the position detection elements 10e and 10f is not condensed.

  As described above, the short-direction shake of each of the position detection elements 10e and 10f is not a problem due to the condenser lens 10c. On the other hand, the shakes in the longitudinal direction are not a problem because they are canceled by taking the displacement difference between the incident positions of the two position detection elements 10e and 10f. From these things, S / N can be maintained. It should be noted that an excessively large vibration that causes the laser light to deviate from the two position detection elements 10e and 10f even by such a method is a problem of the film forming apparatus 1 itself (for example, abnormal vibration or assembly accuracy). ) Or when the substrate W is detached from the counterbore part 5 a of the susceptor 5. Conversely, by properly monitoring the signal from the curvature measuring device, it is possible to quickly find such an abnormality.

  The course changing unit 10d separates the first laser light L1 and the second laser light L2 that are mirror-reflected by the surface of the substrate W, and changes their traveling directions in significantly different directions. For example, a polarization beam splitter (second polarization beam splitter) can be used as the route changing unit 10d. The traveling directions of the first laser light L1 and the second laser light L2 whose paths have been changed are such that the first laser light L1 can be detected by the first position detection element 10e, and the second position detection is performed. The range is such that the second laser beam L2 can be detected by the element 10f. It is also possible to add an optical component such as a mirror between the course changing unit 10d and the position detection element 10e or 10f to change the installation position of the position detection element 10e or 10f.

  The first position detection element 10e receives the first laser light L1 out of the first laser light L1 and the second laser light L2 separated by the course changing unit 10d and detects the incident position (light receiving position). It is a one-dimensional position detecting element. The first position detection element 10e is provided such that the normal direction of the element surface (light receiving surface) is inclined within a range of 10 to 20 degrees from the optical axis of the first laser light L1.

  The second position detection element 10f receives the second laser light L2 out of the first laser light L1 and the second laser light L2 separated by the course changing unit 10d and detects the incident position (light receiving position). It is a one-dimensional position detecting element. Similar to the first position detecting element 10e, the second position detecting element 10f has a normal direction of the element surface (light receiving surface) within a range of 10 to 20 degrees from the optical axis of the second laser light L2. It is provided to tilt.

  In this way, the normal direction of the detection surface of the position detector (the first position detection element 10e and the second position detection element 10f) is intentionally tilted with respect to the direction of the incident laser beam, and reflected from the position detector. It is possible to avoid the laser beam returning to the optical system again (return light). The return light acts as noise on the reflected light from the measurement object that is originally required. By tilting the position detector as described above, the reflected light from the position detecting element 10e or 10f is prevented from entering the path changing unit 10d, and therefore the position detection accuracy is reduced due to the adverse effect of the reflected light (returned light). That can be suppressed.

  The calculating unit 10g uses the incident position of the first laser light L1 detected by the first position detecting element 10e and the incident position of the second laser light L2 detected by the second position detecting element 10f to use the substrate. The curvature (warpage amount) of W is calculated. For example, the calculation unit 10g calculates the amount of displacement of the incident position of the first laser light L1 detected by the first position detection element 10e and the second laser light L2 detected by the second position detection element 10f. The difference between the displacement amount of the incident position is calculated, and the curvature change amount of the substrate W is calculated from the correlation between the calculated difference and the respective optical path lengths of the first laser beam L1 and the second laser beam L2. The curvature before displacement can be converted to an absolute value of the radius of curvature by using a calibration mirror or a substrate without deformation as a reference.

  As an example of the predetermined relational expression indicating the correlation, the displacement amount on the position detector (the first position detecting element 10e and the second position detecting element 10f) corresponding to each of the laser beams L1 and L2 is represented by X1. And X2, where the individual optical path lengths of the laser beams L1 and L2 are Y1 and Y2, and the amount of curvature change is Z1, the relational expression (X1 + X2) / 2 = w × Y × Z1 is given. Here, w is the distance between the irradiation positions of the two laser beams on the measurement object. Y1 and Y2 are assumed to be approximately equal to Y, and the signs of X1 and X2 are set so that the displacements of the two laser beams in the center direction have the same sign.

  Here, it is not realistic to measure w and Y strictly, but on the other hand, since it does not change greatly during the measurement, the total amount of displacement “Xtotal = C × Z1” (Xtotal = X1 + X2) In a simple relationship in which the curvature is proportional to (that is, the change in the geometric distance between the two laser beams), C can be determined and applied by a calibration mirror (two types) having a known radius of curvature. One of the two types should have a radius of curvature as infinite as possible (ie, a plane), and the other should have the smallest possible radius of curvature. If possible, it is preferable to measure those having an intermediate radius of curvature and confirm that linearity (when a calibration curve is created for Z1) is established in the measurement range.

  Moreover, it is preferable that the calculation part 10g takes in the signal from each position detection element 10e and 10f at a predetermined timing. For example, the calculation unit 10g captures a periodic motion phase signal associated with the substrate W and simultaneously captures signals from the position detection elements 10e and 10f, and uses only a position signal in an arbitrary phase range of the periodic motion. To calculate the curvature. For example, when the periodic motion is a rotational motion, each position detection element is synchronized with the rotation of the motor by setting the signal capture timing as the timing of each rotation of the motor of the rotation mechanism (pulse of the Z phase of the motor). The signals from 10e and 10f are captured. The position signal may be information at an arbitrary point, may be an average value in an arbitrary range, and is preferably integrated. If these are difficult, it is recommended that all the information for a plurality of cycles be taken in and averaged.

  Next, the laser beam interval (the distance between the first laser beam L1 and the second laser beam L2) on the surface of the substrate W will be described with reference to FIG. Although it is actually more complicated than FIG. 5, it is a simplified model in order to estimate the order of displacement.

  As shown in FIG. 5, assuming a mirror surface with a radius of curvature R (m), let H be a line segment (radius) extending from a tangent to the mirror surface and passing through the center of the mirror surface. It is assumed that the light beam is incident on the mirror surface parallel to the line segment H and is reflected on the inner side of the mirror surface. Unless the curvature becomes so large, the point where the reflected light beam intersects with the line segment H is approximated as a midpoint (R / 2) of the deformation, and the displacement observation point in the curvature measuring apparatus 10 is high in FIG. It is approximated as L, and the observed displacement when the curvature of the reflected light beam changes is approximated to dZ, and the reflection point of the incident light beam is approximated to be at the same height as the lowest point of the circle.

  Here, if the linear distance between the straight line H and the incident light beam is w (m), dZ is dZ = w−Z = w− (R / 2−L) × tan (2α), and tan (2α) is an approximation. Therefore, tan (2α) = 2α = 2w / R, so that it can be expressed by the equation dZ = w− (R / 2−L) × 2w / R = 2wL / R.

  As an example, if the film formation state of GaN is examined based on a change in the radius of curvature around 100 (m), the resolution of the curvature change can be 100 (m), practically 500 (m). It can be seen that 1000 (m) is preferable. On the other hand, as described above, it is desirable that the distance between the substrate W and each of the position detection elements 10e and 10f is long. However, in reality, disturbance due to convection of air in the optical path (air fluctuation) and installation in the apparatus housing are also possible. Since it must be taken into consideration, it is appropriate that the length is 20 to 50 cm. Here, when the radius of curvature (R) is 500 m or more and the distance (L) is 30 cm, the above equation is dZ = 0.0012w.

  However, the displacement dZ has a lower limit due to the performance of the light receiving element. For example, in a CCD, the element pitch is about 1 μm unless it is very expensive and has high performance. Since PSD is an analog measurement, the limitations of the light receiving element itself are not clear. However, in the performance of a general-purpose logger that captures the signal, 10 nm to 0.1 μm is a reasonable range. Even if it is used, it becomes difficult to distinguish changes in the nm order due to disturbances such as air. As a result, it is practical in most cases if a displacement of about 1 μm can be recognized in practice. Therefore, from the above formula, first, w is preferably 1 mm or more.

  On the other hand, on the side where the curvature is large and the amount of displacement is large, the laser beam interval must be limited to a laser beam width that does not protrude from the light receiving range of the light receiving element and the optical element related to the light collecting system. The radius of curvature may be less than 1 m, and it is better to assume a measurable range up to about R = 0.5 m. In this case, in the above formula, dZ = 1.2w. Relatively general-purpose CCDs and PSDs that are easily available have a light receiving size of about 10 mm square to 20 mm square, and w may be 8 to 16 mm in order for the amount of displacement to be within the light receiving range. However, as for the optical elements up to the light receiving element, for example, if a small one is selected in order to reduce the cost, it is usually limited to 10 mm square. That is, the displacement width is required to be less than 10 mm at most. For this reason, w is 8 mm or less, preferably about 4 mm or less in view of the margin for the change in the positive and negative optical paths.

  Thus, the linear distance (laser interval) w between the straight line H and the incident light beam is preferably 8 mm or less or 4 mm or less, and more preferably 1 mm or more as described above. Therefore, w preferably falls within the range of 1 mm ≦ w ≦ 8 mm, and more preferably falls within the range of 1 mm ≦ w ≦ 4 mm.

  When two optical paths overlap on the surface of the substrate W (that is, when incident on the same point), the inclination of the reflection point becomes the same for both optical paths. That is, both are inclined in the same direction by the same amount. In the two laser systems, since the warpage (curvature) is obtained from the difference in inclination between the two laser systems, detection is not possible in principle if both are the same, and the incident point needs to be shifted even a little. On the other hand, the farther the incident points are from each other, the greater the difference in inclination between the two, and the higher the sensitivity. However, it is difficult to provide a large window in the chamber 2 with the film forming apparatus 1. For this reason, it is desirable to set the laser beam interval within the above-mentioned range, but the laser beam interval should be set out of the above-mentioned range depending on various conditions (for example, window size that can be secured). Is also possible.

  Next, the incident angles of the laser light on the surface of the substrate W (the individual incident angles of the first laser light L1 and the second laser light L2) will be described with reference to FIG.

  FIG. 6 shows the reflectance dependency (relationship between the incident angle and the reflectance) with respect to the incident angle when the substrate W is quartz. Graph B1 is a graph when incident light is S-polarized light, and graph B2 is a graph when incident light is P-polarized light. From these graphs B1 and B2, in S-polarized light and P-polarized light traveling in parallel toward the incident surface, when the incident angle is 0 degree, the reflectance is the same, and the incident angle is 10 degrees or 20 degrees. It is substantially the same to the extent. For this reason, in order to make the reflectances of the S-polarized light and the P-polarized light substantially the same, it is desirable that the light incident angle A1 (see FIG. 2) be at least 20 degrees or less.

  As described above, the curvature measuring apparatus 10 monitors the warpage of the substrate W in the above-described epitaxial film formation step. In this warp monitoring, the first laser beam L1 and the second laser beam L2 having different polarization directions are irradiated by the irradiation unit 10a and incident on the surface of the substrate W in parallel. Next, the first laser light L1 and the second laser light L2 that are specularly reflected by the substrate W pass through the optical filter 10b in parallel, and further pass through the condenser lens 10c, and then by the course changing unit 10d. To be separated. The separated first laser light L1 and second laser light L2 are condensed in the short direction of the first position detection element 10e and the second position detection element 10f by the action of the condenser lens 10c. Of the separated laser beams L1 and L2, the first laser beam L1 is detected by the first position detection element 10e, and the second laser beam L2 is detected by the second position detection element 10f.

  Thereafter, the respective incident positions of the first laser beam L1 and the second laser beam L2 are used by the calculation unit 10g, and the curvature (warping amount) of the substrate W is calculated. For example, the difference between the amount of displacement of the incident position of the first laser beam L1 and the amount of displacement of the incident position of the second laser beam L2 is calculated, and the curvature change of the substrate W is calculated from the correlation between the difference and each optical path length. A quantity (curvature) is calculated. When the calculated curvature is input to the control unit 11, the control unit 11 determines whether or not the input curvature is larger than a predetermined set value, and the curvature measured by the curvature measuring device 10 is predetermined. When it is determined that the value is larger than the set value, it is possible to stop the film forming process and further output a notification instruction to the notification unit 12. When receiving the notification instruction from the control unit 11, the notification unit 12 can perform processing such as notifying the user that there is a problem (warning) in the warpage of the substrate W.

  Here, in the conventional two-point collective CCD method, when the warp is large as described above, the two points may coincide with each other, and there is no distance between the two points. Will exist. On the other hand, according to the present embodiment, the two laser beams L1 and L2 are forcibly separated by the respective polarizability and the path changing unit 10d wherever they overlap. Further, how much the positions of the laser beams L1 and L2 deviate from the original positions is calculated, and the change in the interval is read only by subtraction. Therefore, there is no non-measurable area as in the conventional two-point collective CCD system, and the SN ratio (S / N) in the vicinity thereof does not decrease. In addition, in the conventional two-point collective CCD method, it is necessary to perform optical path adjustment (setting) so as to avoid an unmeasurable region. However, according to the present embodiment, the restriction is eliminated, and the adjustment is robust. Get higher.

  The laser beams L1 and L2 of the curvature measuring apparatus 10 pass through the window of the chamber 2, but the window of the chamber 2 tends to be inclined due to various factors. Examples of the various factors include deformation of the chamber 2 due to heat and displacement due to vibration. Further, the substrate W measured by the curvature measuring apparatus 10 is periodically oscillated by rotation. In addition, in order to prevent the first laser light L1 from being detached from the first position detection element 10e by the condenser lens 10c even if such a window inclination or periodic vibration of the substrate W occurs, The light is collected so that the second laser light L2 does not deviate from the second position detection element 10f. That is, since the first laser beam L1 and the second laser beam L2 that have been fan-shaped due to the tilt of the window and the periodic vibration of the substrate W are collected again at one point, the tilt of the window and the periodic vibration of the substrate W are collected. Therefore, it is possible to prevent the curvature measurement accuracy from being lowered.

  As described above, according to the first embodiment, the first laser light L1 and the second laser light L2 having different polarization directions are incident on the substrate W in parallel, and are specularly reflected by the substrate W. The paths of the first laser light L1 and the second laser light L2 are changed so that they are not mixed by the path changing unit 10d, and the first laser light L1 and the second laser light L2 whose paths are changed are further changed. Detection is performed by the first position detection element 10e and the second position detection element 10f, respectively. For this reason, unlike the case where the conventional two-point collective CCD system is used, the two points on the CCD element surface do not coincide with each other and are separated even if the two laser beams L1 and L2 overlap. Are detected by two position detecting elements 10e and 10f, respectively. Thus, unlike the conventional two-point collective CCD method, measurement is not impossible, and deterioration of the S / N ratio (S / N) is suppressed even when warping is large or between the two points is narrowed. It becomes possible. Accordingly, it is possible to realize inhibition of the inability to measure curvature and improvement in curvature measurement accuracy.

(Second Embodiment)
A second embodiment will be described with reference to FIG. In the second embodiment, differences from the first embodiment (component arrangement of the curvature measuring device 10) will be described, and other descriptions will be omitted. FIG. 7 shows a schematic structure of the curvature measuring apparatus 10 using schematic diagrams of optical parts, as in FIGS. 2 to 4 described above. The distance between the curvature measuring apparatus 10 and the substrate W is as follows. Although shown shortly, the actual separation distance is about 20 to 50 cm, and the laser beam passes through the window of the chamber 2. Although the direction of the laser beam reflected by the polarizing beam splitter is shown to be bent at a substantially right angle, this angle does not need to be in the vicinity of a right angle in some cases.

  As shown in FIG. 7, the irradiation unit 10 a of the curvature measuring apparatus 10 according to the second embodiment includes a laser beam emitting unit (light emitting unit) 21 that emits a laser beam, and the laser beam as a first laser beam. A polarization beam splitter 22 that splits into L1 (S-polarized light) and second laser light L2 (P-polarized light) and a mirror 23 are provided. The polarization beam splitter 22 is provided on the optical path between the laser beam emitting portion 21 and the surface of the substrate W, and the mirror 23 applies the first laser beam L1 separated by the polarization beam splitter 22 to the substrate W. It is provided at a position that reflects toward the surface.

  The irradiation unit 10a separates the laser beam emitted from the laser beam emitting unit 21 into the first laser beam L1 and the second laser beam L2 by the polarization beam splitter 22, and the second laser beam L2 is directly used as the substrate W. The first laser beam L1 is reflected by the mirror 23 so as to be parallel to the second laser beam L2, and is incident on the surface of the substrate W.

  The optical filter 10b, the condensing lens 10c, the course changing unit 10d, and the second position detecting element 10f are provided on a substantially normal line of the substrate W, and the first position detecting element 10e is advanced by the course changing unit 10d. The first laser beam L1 whose direction has been changed is provided at a position where it can be detected. Further, the two beam splitters 22 and 10d used in this embodiment having the configuration shown in FIG. 7 are both P-polarized transmission type polarization beam splitters.

  In the curvature measuring apparatus 10 having such a configuration, the four optical paths including the incident optical path to the substrate W and the reflected optical path from the substrate W in the first laser light L1 and the second laser light L2 are all substantially in the same plane. In addition, the reflected light path is adjusted to a position sandwiched between the incident light paths. Thereby, in all the optical paths of the incident optical path and the reflected optical path that pass through the window of the chamber 2, it is possible to reduce the separation distance between the optical paths located on the outer periphery thereof. For this reason, the window of the chamber 2 through which the laser beams L1 and L2 pass can be reduced, and as a result, it is possible to prevent the detection position accuracy from being lowered due to the inclination of the window due to heat or the like.

  As described above, according to the second embodiment, it is possible to obtain the same effects as those of the first embodiment described above, and it is possible to realize the suppression of the inability to measure the curvature and the improvement in the accuracy of the curvature measurement. it can. Furthermore, since the window of the chamber 2 through which each of the laser beams L1 and L2 passes can be made small, it is possible to prevent the detection position accuracy from being lowered due to the inclination of the window due to heat or the like.

(Supplement to the first or second embodiment described above)
Here, a part of various features in the first or second embodiment will be listed.

  The incident angles of the laser light on the substrate W, that is, the first laser light L1 and the second laser light L2, are at least 20 degrees or less (see FIG. 2). As a result, when the first laser beam L1 and the second laser beam L2 are S-polarized light and P-polarized light, their reflectances can be made substantially the same (see FIG. 6). Accuracy can be improved.

  Further, the optical paths of the first laser beam L1 and the second laser beam L2 are such that when the path changing unit 10d is removed (in a state), the optical paths of the second laser beam L1 are the element surfaces (light receiving surfaces) of the second position detection element 10f. ) So as to cross each other (see FIG. 2). As a result, the distance between the optical paths of the laser beams L1 and L2 can be reduced, and the path changing unit 10d can be downsized. Note that the above-described intersection position is desirably the center in the longitudinal direction of the second position detection element 10f. Thus, even if the irradiation position of the laser light L1 or L2 moves on the light receiving surface of the position detector 10f or 10e due to periodic vibration of the substrate W, the irradiation position becomes the end of the light receiving surface extremely. Or the possibility of detachment from the light receiving surface can be reduced, and a decrease in position detection accuracy can be suppressed.

  The light receiving surface (first light receiving surface) of the first position detection element 10e is inclined at least 10 degrees from the optical axis of the first laser light L1 (the optical axis of the incident light). Similarly, the light receiving surface (second light receiving surface) of the second position detection element 10f is also inclined at least 10 degrees from the optical axis of the second laser light L2 (the optical axis of the incident light). As a result, it is possible to prevent the reflected light from the position detection element 10e or 10f from entering the path changing unit 10d, and thus it is possible to suppress a decrease in position detection accuracy due to an adverse effect of the reflected light.

  In addition, an optical filter 10b that does not pass wavelengths other than those near the wavelengths of the first laser beam L1 and the second laser beam L2 is installed on the optical path from the substrate W to the path changing unit 10d. As a result, light having a wavelength other than the vicinity of the wavelengths (for example, green) of the laser beams L1 and L2 is prevented from entering the position detection elements 10e and 10f. The position detection accuracy can be improved.

  In addition, a periodic motion phase signal associated with the substrate W is captured, and at the same time, signals from the position detection elements 10e and 10f are captured, and the curvature is calculated using only the position signal in an arbitrary phase of the periodic motion. . For example, when the periodic motion is a rotational motion, the signal capturing timing is the timing of each rotation of the motor of the rotating mechanism (motor Z-phase pulse), and each position detection element is synchronized with the motor rotation. The signals from 10e and 10f are captured. As a result, even when there is vibration due to periodic motion, it becomes possible to read and use the signal at a timing synchronized with the motion, so it is possible to prevent the position detection accuracy from being degraded due to periodic vibration. The position detection accuracy can be improved as compared with the case where the signal is read and used at a timing not synchronized with the periodic motion.

  In addition, one or both of the one-dimensional position detection elements 10e and 10f are semiconductor position detection elements (PSDs) that output the center of gravity of the incident laser light distribution as two electrical signals. Alternatively, one or both of the one-dimensional position detection elements 10e and 10f is a solid-state imaging element (for example, a CCD). Here, in the conventional two-point collective CCD system, since the distance between two points is determined by complicated image processing, a high-speed computer is required, and the cost increases. On the other hand, if the processing speed is sacrificed in order to reduce the cost, the device performance is degraded. When PSD is used, image processing is unnecessary, and it is sufficient to read an analog signal for each PSD and execute simple calculations such as four arithmetic operations, thereby suppressing an increase in cost and a decrease in apparatus performance. Further, even when a CCD is used, it is possible to grasp the incident position by simple image processing compared to two-dimensional image processing, and it is possible to suppress an increase in cost and a decrease in apparatus performance.

  In the second embodiment, the four optical paths including the incident optical path to the substrate W and the reflected optical path from the substrate W in the two laser beams L1 and L2 are all adjusted to substantially the same plane. The reflected light path is adjusted to a position sandwiched between the incident light paths. Thereby, in all the optical paths of the incident optical path and the reflected optical path that pass through the window of the chamber 2, it is possible to reduce the separation distance between the optical paths located on the outer periphery thereof. For this reason, the window of the chamber 2 through which the laser beams L1 and L2 pass can be reduced, and as a result, it is possible to prevent the detection position accuracy from being lowered due to the inclination of the window due to heat or the like.

(Third embodiment)
A third embodiment will be described with reference to FIG. In the third embodiment, differences from the first embodiment (component arrangement and configuration of the curvature measuring apparatus 10) will be described, and other descriptions will be omitted. FIG. 8 shows a schematic structure of the curvature measuring device 10 using a schematic diagram of an optical component, and the distance between the curvature measuring device 10 and the substrate W is the same as in FIGS. 2 to 4 described above. Although shown shortly, the actual separation distance is about 20 to 50 cm, and the laser beam passes through the window of the chamber 2. Although the direction of the laser beam reflected by the polarizing beam splitter is shown to be bent at a substantially right angle, this angle does not need to be in the vicinity of a right angle in some cases.

  As shown in FIG. 8, the curvature measuring apparatus 10 according to the third embodiment differs from the first embodiment (further, the second embodiment) in the incident light perpendicular to the surface of the substrate W that is the measurement object. And the curvature is measured using the reflected light (the incident angle of the laser light is 90 degrees, and the incident light and the reflected light have the same optical axis).

  The curvature measuring apparatus 10 includes a quarter wavelength plate 10h through which two laser beams L1 and L2 pass, in addition to the irradiation unit 10a, the first position detection element 10e, the second position detection element 10f, and the calculation unit 10g. And a polarization beam splitter 10i that reflects the first laser light L1 out of the two laser lights L1 and L2 mirror-reflected by the surface of the substrate W. The polarization beam splitter 10i is provided in place of the course changing unit 10d according to the first embodiment.

  The irradiation unit 10a separates a laser beam emitting unit (light emitting unit) 21 that emits a laser beam and a first laser beam L1 (P-polarized light) and a second laser beam L2 (S-polarized light). A polarization beam splitter 22 and a mirror 23 that reflects the second laser light L2 are provided.

  The polarizing beam splitter (first polarizing beam splitter) 22 is provided between the laser light emitting portion 21 and the surface of the substrate W, that is, the first laser light L1 emitted from the laser light emitting portion 21 is on the surface of the substrate W. It is provided on the optical path that is perpendicularly incident. This polarization beam splitter 22 transmits substantially P-polarized light and substantially reflects S-polarized light (bending only S-polarized light by, for example, 90 degrees).

  The mirror 23 reflects the second laser light L2 (S-polarized light) separated by the polarization beam splitter 22 toward the surface of the substrate W in parallel with the first laser light L1 (P-polarized light). It functions as a reflection part that reflects the second laser beam L2 (P-polarized light) that has been specularly reflected by the surface of W and passed through the quarter-wave plate 10h (bending S-polarized light and P-polarized light by 90 degrees, for example).

  The first position detection element 10e detects the incident position of the first laser beam L1 that is specularly reflected by the surface of the substrate W and reflected by the polarization beam splitter 10i. Further, the second position detection element 10 f detects the incident position of the second laser light L 2 that is specularly reflected by the surface of the substrate W and reflected by the mirror 23. The first position detection element 10e and the second position detection element 10f are arranged on the same straight line, for example, but are not limited thereto.

  The quarter-wave plate 10h includes an optical path where the first laser light L1 is perpendicularly incident on the surface of the substrate W and an optical path where the second laser light L2 is incident on the surface of the substrate W parallel to the first laser light L1. Are provided on both optical paths. For this reason, the quarter-wave plate 10h includes the first laser light L1 that is perpendicularly incident on the surface of the substrate W and the second laser light L2 that is incident on the surface of the substrate W in parallel to the first laser light L1. , And the first laser beam L1 and the second laser beam L2 that are specularly reflected by the surface of the substrate W pass through.

  Each of the laser beams L1 and L2 has a property that the polarization direction changes 90 degrees when passing through the quarter-wave plate 10h twice (when it passes once, it becomes circularly polarized light). Therefore, when the P-polarized light passes through the quarter-wave plate 10h twice, the polarization direction changes 90 degrees to become S-polarized light. Conversely, when the S-polarized light passes through the quarter-wave plate 10h twice, the polarization direction changes. It changes by 90 degrees to become P-polarized light. Further, since the circularly polarized light is obtained by shifting the optical axis of the quarter wavelength plate by 45 degrees with respect to the polarization plane of the linearly polarized light, the first laser light L1 and the second laser light having the orthogonal polarization directions are obtained. By adjusting the optical axis in the middle of the polarization direction of the laser beam L2, a symmetrical condition can be given to the two laser beams L1 and L2.

  The polarization beam splitter (second polarization beam splitter) 10i is provided on the optical path where the first laser light L1 is perpendicularly incident on the surface of the substrate W, and is first specularly reflected by the surface of the substrate W. The first laser beam L1 (S-polarized light) is reflected toward the first position detection element 10e. This polarization beam splitter 10i transmits almost P-polarized light and substantially reflects S-polarized light (bending only S-polarized light by 90 degrees, for example).

  Such a curvature measuring apparatus 10 monitors the warpage of the substrate W in the above-described epitaxial film forming step. In this warpage monitoring, when the laser light is emitted from the laser light emitting unit 21, first, the first laser light L1 (P-polarized light) and the second laser light L2 (S-polarized light) whose polarization directions are different from each other by 90 degrees. It is separated by the polarization beam splitter 22. Next, the first laser beam L1 passes through the polarizing beam splitter 10i and the quarter-wave plate 10h and enters the surface of the substrate W perpendicularly. The second laser beam L2 is reflected by the mirror 23 and becomes parallel to the first laser beam L1, passes through the quarter-wave plate 10h, and enters the surface of the substrate W.

  Next, the first laser beam L1 specularly reflected by the surface of the substrate W passes through the quarter-wave plate 10h, changes its polarization direction, and becomes S-polarized light. The first laser light L1 (S-polarized light) is reflected by the polarization beam splitter 10i, enters the first position detection element 10e, and is detected by the first position detection element 10e. The second laser light L2 specularly reflected by the surface of the substrate W passes through the quarter-wave plate 10h, changes its polarization direction, and becomes P-polarized light. The second laser beam L2 (P-polarized light) is reflected by the mirror 23 toward the polarization beam splitter 22, passes through the polarization beam splitter 22, and enters the second position detection element 10f. It is detected by the position detection element 10f. Subsequent processing (such as calculation of curvature of the substrate W and warning notification) is the same as in the first embodiment.

  Note that, on the optical path of the first laser light L1 between the first position detection element 10e and the polarization beam splitter 10i and on the optical path of the second laser light L2 between the second position detection element 10f and the polarization beam splitter 22, It is also possible to provide a direction changing section such as a direction changing mirror so as to reflect the laser light upward in FIG. In this case, the degree of freedom of installation of the first position detection element 10e and the second position detection element 10f can be improved.

  In addition, while maintaining that the first laser light L1 is perpendicularly incident on the surface of the substrate W, and the second laser light L2 is incident on the surface of the substrate W in parallel to the first laser light L1, The polarizing beam splitter 22, the mirror 23, the polarizing beam splitter 10i, and the like are tilted so that the optical path of the first laser light L1 between the first position detecting element 10e and the polarizing beam splitter 10i, the second position detecting element 10f, and the polarizing beam It is also possible to make the optical path of the second laser light L2 between the splitters 22 non-parallel.

  The two beam splitters 10i and 22 used in the third embodiment shown in FIG. 8 are both P-polarized transmission type, but the same function can be realized even if these two beam splitters are both S-polarized transmission type. can do. Further, the first polarizing beam splitter 22 and the second polarizing beam splitter 10i may be different transmission types (S transmission type and P transmission type). In this case, as shown in FIG. 9, the second polarizing beam splitter 10i is placed between the mirror 23 and the quarter wavelength plate 10h in the optical path of the second laser light L2. The first position detecting element 10e detects the position of the first laser beam L1 reflected by the first polarizing beam splitter 22, and the second position detecting element 10f is reflected by the second polarizing beam splitter 10i. The position of the second laser beam L2 is detected.

  In recent years, the size of the window of the chamber 2 has been reduced, and the restrictions on the window have become severe. In order to reduce the size of the window while reducing the space on the chamber 2 and reducing the noise caused by the deformation of the window, measurement with vertical incident reflection is performed. Therefore, it is desired to suppress the loss of light quantity. As described above, since the laser beam is separated into the first laser beam L1 and the second laser beam L2 by the polarization beam splitter 22, the amount of the light is halved, but after the separation, the first laser beam L1 and the second laser beam L2 are separated. Even if the second laser beam L2 is reflected by an optical system such as the polarization beam splitter 10i or the mirror 23, the respective light amounts are hardly decreased, and loss of the light amount can be suppressed. Therefore, in the measurement with vertical incident reflection, there is no significant decrease in light (unnecessary scattering) from incident to reflection, and the loss of light quantity can be suppressed.

  Furthermore, in the vertical incident reflection measurement, the first laser light L1 and the second laser light L2 always maintain their polarization directions orthogonal to each other after being separated. Even if the laser beams L1 and L2 overlap, it is possible to suppress the inability to measure the curvature, and in addition, it is possible to improve the accuracy of the curvature measurement. In the measurement by vertical incident reflection, only the direction of the reflected light can be changed to the direction of a detector such as the first position detecting element 10e or the second position detecting element 10f.

  As described above, according to the third embodiment, the first laser light L1 and the second laser light L2 having different polarization directions are incident on the substrate W in parallel and are specularly reflected by the substrate W. The first laser beam L1 and the second laser beam L2 are not mixed but detected by the first position detection element 10e and the second position detection element 10f, respectively. The traveling directions of the laser beams L1 and L2 do not necessarily have to be strictly parallel, but may be approximately parallel. Therefore, unlike the case where the conventional two-point collective CCD system is used, the two points on the CCD element surface do not coincide with each other, and even if the two laser beams L1 and L2 overlap, the polarization property Are detected by two position detection elements 10e and 10f, respectively. Thus, unlike the conventional two-point collective CCD method, measurement is not impossible, and deterioration of the S / N ratio (S / N) is suppressed even when warping is large or between the two points is narrowed. It becomes possible. Accordingly, it is possible to realize inhibition of the inability to measure curvature and improvement in curvature measurement accuracy.

  Further, after the laser light is separated, the first laser light L1 and the second laser light L2 are reflected by an optical system such as the polarizing beam splitter 10i and the mirror 23, and thus the respective light amounts are hardly reduced. Loss can be suppressed. In addition, by adopting the measurement by vertical incident reflection, it is possible to reduce the window of the chamber 2 through which each of the laser beams L1 and L2 passes, so that the detection position accuracy is lowered by the inclination of the window due to heat or the like. Can be deterred.

(Other embodiments)
In the first to third embodiments described above, the laser beams L1 and L2 are not formed into a sheet shape. However, the present invention is not limited to this, and may be formed into a sheet shape. For example, as shown in FIG. 10, the laser beam L1 and L2 are transmitted to the one-dimensional position detection elements 10e and 10f in the element array direction (longitudinal direction) by a molding part 10j such as a semi-cylindrical lens or a unidirectional diffusion filter. The sheet may be stretched in a direction perpendicular to the width direction (short direction) and formed into a sheet shape extending in the short direction. The molding unit 10j is provided on the optical path between the irradiation unit 10a and the substrate W. As a result, even when the laser beams L1 and L2 are shifted in the short direction of the one-dimensional position detection element 10e or 10f due to periodic vibration (for example, vibration of the substrate W due to rotation, etc.), Since it is in the form of a sheet, it surely enters the condenser lens 10c (even if there is no condenser lens 10c, it surely enters the one-dimensional position detection element 10e or 10f). Thereby, since each laser beam L1 and L2 is condensed by the condensing lens 10c and surely enters the one-dimensional position detection element 10e or 10f, it is possible to suppress a decrease in position detection accuracy due to periodic vibration. it can. When periodic vibration occurs in the substrate W, the laser light L1 or L2 is not only shifted in the short direction of the position detection element 10e or 10f, but the substrate W of the measurement object is rotated. It will shift to draw a circle according to the rotation. Even in such a case, each of the laser beams L1 and L2 is in the form of a sheet in the short direction described above, and thus is surely incident on the condenser lens 10c.

  In the first to third embodiments described above, the first laser beam L1 that is parallel or parallel by the laser beam emitting unit 21, the polarization beam splitter 22, the mirror 23, and the like is used as the irradiation unit 10a. Although the second laser beam L2 is generated, the present invention is not limited to this. For example, the first laser beam L1 and the second laser beam that are parallel or parallel using two laser beam emitting units are used. It is also possible to generate the laser beam L2. Since the amount of light of each laser beam L1 and L2 tends to be scraped by the presence of the window of the chamber 2, etc., the amount of light can be reduced by using two laser beam emitting units compared to the case of using one laser beam emitting unit. Can be raised. In this case, the polarization beam splitter 22 on the incident side can be made unnecessary. However, since there is a polarizing plate for improving the polarization and the size of the laser light emitting part main body, It is desirable to provide a mirror for bringing the laser beams L1 and L2 closer together, a cooling system for the laser beam emitting portion main body, and the like. Further, since the space for installing the curvature measuring apparatus 10 (the upper part of the film forming apparatus 1) is narrow, the housing is preferably small. In order to avoid the increase in the number of parts described above, an external light source is used as a fiber. It is also possible to bring in light.

  Further, in the first to third embodiments described above, the curvature of the substrate W is measured by the curvature measuring device 10, but the present invention is not limited to this. For example, the curvature is applied in addition to the curvature. Thus, the inclination and height position of the substrate W can be measured.

  In the first to third embodiments, the shower plate 4 and the curvature measuring device 10 are not cooled. However, the present invention is not limited to this. For example, the shower plate 4 and the curvature measuring device 10 are not limited thereto. It is possible to provide a cooling device for cooling the shower plate 4 and the curvature measuring device 10 by the cooling device.

  In the embodiments described so far, in the plane including the optical paths of the two laser beams incident on the measurement target, one of the laser beams reflected from the measurement target is reflected by the second polarizing beam splitter. (Direction in the paper surface in FIGS. 2, 3, and 7 to 10). On the other hand, it is possible to make the reflection direction perpendicular to the above-mentioned plane (perpendicular to the paper surface in FIGS. 2, 3, and 7 to 10). This can be realized by simply rotating the second polarizing beam splitter by 90 ° about the optical path of the incident laser beam. By making such a change, the degree of freedom of the shape of the curvature measuring device of the present embodiment increases, and it becomes easy to install in a constrained space.

  When the reflection direction is changed, the polarization is reversed because the second polarization beam splitter is rotated by 90 °. It should be noted that originally S or P polarized laser light becomes P or S polarized light respectively in the polarization beam splitter rotated as described above. When the reflection direction is changed, the position change of the laser beam reflected by the second polarization beam splitter on the position detector due to the change in the curvature of the measurement object is rotated by 90 °. Specifically, in the case of FIG. 3, the effect of rotating the second polarizing beam splitter by 90 ° as described above is shown in FIGS. FIG. 11 shows the relationship between the incident surface of the second polarization beam splitter 10d, the incident laser beam, and the laser beam reflected by the second polarization beam splitter 10d in the case of FIG. It is shown. As shown in FIG. 11, the direction of the laser light reflected by the second polarizing beam splitter 10d changes substantially in the vertical direction in response to the change in the warp of the substrate W that is the measurement object. This change in position is substantially in the vertical direction on the paper surface in FIG. On the other hand, FIG. 12 shows a case where the second polarizing beam splitter 10d is rotated by 90 °. As shown in FIG. 12, the laser beam reflected by the second polarizing beam splitter 10d is reflected in a direction perpendicular to the paper surface in FIG. Corresponding to the change in warpage of the measurement object, the direction of the laser light reflected by the second polarization beam splitter 10d changes in a substantially horizontal direction. It should be noted that this is substantially the left-right direction in FIG.

  Further, taking the case of FIG. 9 as an example, consider a case where the second polarization beam splitter 10i is rotated by 90 ° about the direction of the second laser light L2. In this case, by making the second polarization beam splitter 10i a P-polarized light transmission type, a function equivalent to the configuration of FIG. 9 can be realized. However, the direction in which the second laser beam L2 is reflected is perpendicular to the paper surface in FIG.

  In this embodiment, film formation by MOCVD is given as a main application example. However, if there is a possibility that a warpage change of the substrate accompanying film formation may occur, not only MOCVD but also techniques such as sputtering and vapor deposition can be used. Needless to say, the present invention can be applied to general warpage measurement not limited to film formation. In this embodiment, a single-wafer type apparatus is cited as a main application example, but the present invention is not limited to a single-wafer type apparatus, and is also applicable to, for example, a batch processing apparatus (multiple sheets simultaneous processing). It is possible.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2 Chamber 3 Gas supply part 3a Gas storage part 3b Gas pipe 3c Gas valve 4 Shower plate 4a Gas supply flow path 4b Gas discharge hole 5 Susceptor 5a Opening part 6 Rotating part 6a Cylindrical part 6b Rotating body 6c Shaft 7 Heater 7a Wiring 8 Gas exhaust part 9 Exhaust mechanism 9a Gas exhaust flow path 9b Exhaust valve 9c Vacuum pump 10 Curvature measuring device 10a Irradiation part 10b Optical filter 10c Condensing lens 10d Path change part 10e First position detection element 10f Second position detection Element 10g Calculation unit 10h 1/4 wavelength plate 10i Polarization beam splitter 10j Molding unit 11 Control unit 12 Notification unit 21 Laser beam emitting unit 22 Polarization beam splitter 23 Mirror L1 First laser beam L2 Second laser beam R1 First region R2 2nd region W substrate

Claims (14)

A light emitting portion for emitting laser light;
A first polarization beam splitter that separates the laser light emitted by the light emitting unit into a first laser light and a second laser light, each having a different polarization direction and traveling direction;
A reflection unit that reflects either the first laser beam or the second laser beam so that the first laser beam and the second laser beam travel to the object to be measured in parallel;
A second polarizing beam splitter that transmits one of the first laser light and the second laser light specularly reflected by the measurement object and reflects the other in a direction different from the one traveling direction; ,
A one-dimensional first position detecting element for detecting an incident position of the first laser beam reflected by the second polarizing beam splitter or transmitted through the second polarizing beam splitter;
A one-dimensional second position detecting element that detects an incident position of the second laser beam that has been transmitted through the second polarizing beam splitter or reflected by the second polarizing beam splitter;
A curvature measuring device comprising: A light emitting portion for emitting laser light;
A first polarization beam splitter that separates the laser light emitted by the light emitting unit into a first laser light and a second laser light, each having a different polarization direction and traveling direction;
A reflection unit that reflects the second laser light so that the first laser light and the second laser light travel in parallel to the measurement object;
A second polarization beam splitter that transmits one of the first laser light and the second laser light traveling toward the measurement object;
The first laser light and the second laser light traveling toward the measurement object pass, and the first laser light and the second laser light that are specularly reflected by the measurement object pass. A quarter wave plate,
A first position detecting element and a second position detecting element for detecting respective incident positions of the first laser light and the second laser light that are specularly reflected by the measurement object and pass through the quarter-wave plate. A position detection element;
A curvature measuring device comprising:   When the first laser beam traveling toward the measurement object is transmitted through the second polarization beam splitter, the second polarization beam splitter is specularly reflected by the measurement object and is the quarter wavelength. The first laser light that has passed through the plate is reflected, and the reflection unit reflects the second laser light that has been specularly reflected by the measurement object and passed through the quarter-wave plate, and The position detection element detects an incident position of the first laser beam reflected by the second polarization beam splitter, and the second position detection element detects the second position reflected by the reflection unit. The curvature measuring apparatus according to claim 2, wherein an incident position of the laser beam is detected.   When the second laser light traveling toward the measurement object passes through the second polarization beam splitter, the first polarization beam splitter is specularly reflected by the measurement object and is the quarter wavelength. The first laser beam that has passed through the plate is reflected, and the second polarizing beam splitter reflects the second laser beam that has been specularly reflected by the measurement object and passed through the quarter-wave plate. The first position detecting element detects the incident position of the first laser beam reflected by the first polarizing beam splitter, and the second position detecting element is the second polarizing beam splitter. The curvature measuring apparatus according to claim 2, wherein an incident position of the second laser beam reflected by the laser beam is detected.   A displacement amount of the incident position of the first laser beam detected by the first position detection element and a displacement amount of the incident position of the second laser beam detected by the second position detection element. A calculation unit that calculates a difference, and calculates a curvature change amount of the measurement object from a correlation between the calculated difference and each optical path length of the first laser beam and the second laser beam; The curvature measuring apparatus according to any one of claims 1 to 4, wherein the curvature measuring apparatus is characterized in that:   The first position detection element and the second position detection element detect a displacement of the shortest distance between two lines of the first laser light and the second laser light reflected by the measurement object. The curvature measuring device according to any one of claims 1 to 5, wherein   The first laser beam is condensed in a direction perpendicular to the element array direction of the first position detection element, and the second laser beam is condensed in a direction perpendicular to the element array direction of the second position detection element. The curvature measuring device according to any one of claims 1 to 6, further comprising a condensing lens for condensing light.   The curvature measuring apparatus according to any one of claims 1 to 7, wherein the light emitting unit emits laser light having a wavelength of 700 nm or less as the laser light. The first position detecting element has a first light receiving surface on which the first laser light is incident,
The normal direction of the first light receiving surface is inclined at least 10 degrees from the optical axis of the first laser beam,
The second position detection element has a second light receiving surface on which the second laser light is incident,
The curvature according to any one of claims 1 to 8, wherein the normal direction of the second light receiving surface is inclined at least 10 degrees from the optical axis of the second laser beam. measuring device.   Molding in which the first laser light is stretched in a direction perpendicular to the element array direction of the first position detection elements, and the second laser light is stretched in a direction perpendicular to the element array direction of the second position detection elements. The curvature measuring apparatus according to claim 1, further comprising a unit. A step of emitting laser light by the light emitting portion;
Separating the laser light emitted by the light emitting unit into a first laser light and a second laser light having different polarization directions and traveling directions, respectively, by a first polarization beam splitter;
Reflecting one of the first laser light and the second laser light by a reflecting portion so that the first laser light and the second laser light travel to the measurement object in parallel;
One of the first laser light and the second laser light specularly reflected by the measurement object is transmitted, and the other is reflected by the second polarization beam splitter in a direction different from the one traveling direction. Process,
Detecting an incident position of the first laser beam reflected by the second polarizing beam splitter or transmitted through the second polarizing beam splitter by a one-dimensional first position detecting element;
Detecting an incident position of the second laser light transmitted through the second polarizing beam splitter or reflected by the second polarizing beam splitter by a one-dimensional second position detecting element;
The curvature measuring method characterized by having. A step of emitting laser light by the light emitting portion;
Separating the laser light emitted by the light emitting unit into a first laser light and a second laser light having different polarization directions and traveling directions, respectively, by a first polarization beam splitter;
Reflecting the second laser light by a reflecting portion so that the first laser light and the second laser light travel to the measurement object in parallel;
Transmitting one of the first laser beam and the second laser beam traveling toward the measurement object by a second polarization beam splitter;
The first laser light and the second laser light traveling toward the measurement object are passed through a quarter-wave plate, and the first laser light and the second laser light that have been specularly reflected by the measurement object. Passing a laser beam through the quarter-wave plate;
The respective incident positions of the first laser beam and the second laser beam that have been specularly reflected by the measurement object and passed through the quarter-wave plate are respectively determined as a first position detection element and a second position detection. Detecting with an element;
The curvature measuring method characterized by having.   When the first laser beam traveling toward the measurement object passes through the second polarization beam splitter, the first laser is specularly reflected by the measurement object and passes through the quarter-wave plate. The second laser beam reflected by the second polarization beam splitter and detected by the first position detection element is reflected by the measurement object and passed through the quarter-wave plate. The curvature measurement method according to claim 12, wherein the curvature is reflected by a reflection portion and detected by the second position detection element.   When the second laser beam traveling toward the measurement object passes through the second polarization beam splitter, the first laser is specularly reflected by the measurement object and passes through the quarter-wave plate. Light is reflected by the first polarization beam splitter and detected by the first position detection element, and the second laser light that is specularly reflected by the measurement object and passes through the quarter-wave plate is The curvature measuring method according to claim 12, wherein the curvature is reflected by a second polarizing beam splitter and detected by the second position detecting element.

Images