Method for Measuring Thickness of Protective Film

Abstract

To accurately measure a thickness of a protective film formed on a substrate surface having a pattern.SOLUTION: A method for measuring a thickness of a protective film formed on a surface 900 of a substrate 90, having a pattern 909, includes the steps of: irradiating the surface 900 of the substrate 90 in a state where the protective film is not formed with light to measure first reflection intensity of reflected light from the surface 900; forming protective film 92 containing a light absorbing material; irradiating excitation light having a wavelength causing the light absorbing material to emit fluorescence toward the protective film 92 to measure second reflection intensity including the fluorescence of the protective film 92 and reflected light from the surface 900; calculating fluorescence intensity of the protective film 92 by subtracting the measured first reflection intensity from the measured second reflection intensity to remove the reflection intensity caused by the pattern 909 formed on the surface 900; and recognizing a thickness of the protective film 92 from correlation data acquired in advance between the protective film fluorescence intensity and a thickness of the protective film, and calculated fluorescence intensity of the protective film 92.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for measuring the thickness of a protective film formed on the surface of a substrate having a pattern on its surface.

Background Art

[0002] There are cases where it is desired to form a protective film by applying a liquid resin or the like on one surface of a semiconductor substrate and measure the film thickness of the formed protective film. For example, conventionally, as disclosed in Patent Document 1, a method has been proposed in which light is irradiated onto a protective film containing a light-absorbing material, and the intensity of fluorescence emitted from the protective film is measured by the light-absorbing material absorbing light, thereby measuring the thickness of the protective film. And a method has been proposed in which the relationship between the fluorescence intensity and the film thickness is recorded in advance, and the film thickness is measured based on the obtained fluorescence intensity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a device pattern having a different reflectance from others is formed on the surface of a semiconductor substrate depending on the location, and a protective film is formed on the surface where the pattern is formed, the measured fluorescence intensity is the sum of the fluorescence of the protective film and the light reflected from the pattern surface, so there is a problem that the film thickness cannot be accurately measured.

[0005] Therefore, when measuring the thickness of a protective film formed on the surface of a substrate having a pattern on its surface, there is a problem of enabling accurate measurement of the thickness of the protective film.

Means for Solving the Problems

[0006] The present invention for solving the above problems is a method for measuring the thickness of a protective film formed on a surface of a substrate having a pattern on the surface, the method including: a pre-protective film formation measurement step of irradiating light onto the surface of the substrate in a state where the protective film is not formed and measuring a first reflection intensity of reflected light from the surface; a protective film formation step of forming the protective film containing an absorptive material on the surface; a post-protective film formation measurement step of irradiating excitation light having a wavelength at which the absorptive material fluoresces toward the protective film and measuring a second reflection intensity including fluorescence of the protective film and reflected light from the surface by a measurement unit; a protective film fluorescence intensity calculation step of removing the reflection intensity due to the pattern formed on the surface by subtracting the first reflection intensity measured in the pre-protective film formation measurement step from the second reflection intensity measured in the post-protective film formation measurement step and calculating the fluorescence intensity of the protective film; and a protective film thickness recognition step of recognizing the thickness of the protective film from correlation data between the fluorescence intensity of the protective film and the thickness of the protective film acquired in advance and the calculated fluorescence intensity of the protective film. When measuring the first reflection intensity of a plurality of substrates in the pre-protective film formation measurement step, between the first substrate and the second and subsequent substrates when there is a deviation in the position of the substrate, a correction value for the deviation is obtained, and in the post-protective film formation measurement step earlier than in 、 the the second and subsequent substrate the first reflection intensity data table is corrected by the correction value. This is a method for measuring the thickness of the protective film.

[0007] Preferably, the measurement unit can function as an imaging unit. In the pre-protective film formation measurement step, the imaging unit images the surface of the substrate. In the post-protective film formation measurement step, the imaging unit images the surface of the protective film formed on the surface of the substrate. The first reflection intensity and the second reflection intensity are preferably measured by the luminance of each pixel of the respective images acquired by the imaging unit.

[0008] In the pre-protective film formation measurement step and the post-protective film formation measurement step, the light source that irradiates light onto the surface of the substrate is a white light source, and it is preferable to arrange a first filter that transmits only light of a specific wavelength between the light source and the substrate.

[0009] In the pre-protective film formation measurement step and the post-protective film formation measurement step, the light source that irradiates light onto the surface of the substrate is a white light source, and it is preferable to arrange a second filter that transmits only light of a specific wavelength between the substrate and the measurement unit.

Advantages of the Invention

[0010] The method for measuring the thickness of a protective film according to the present invention, which measures the thickness of a protective film formed on the surface of a substrate having a pattern on its surface, includes a pre-protective film formation measurement step of irradiating light onto the surface of the substrate in a state where the protective film is not formed and measuring a first reflection intensity of the reflected light from the surface; a protective film formation step of forming a protective film containing a light-absorbing material on the surface; a post-protective film formation measurement step of irradiating excitation light having a wavelength at which the light-absorbing material fluoresces toward the protective film and measuring a second reflection intensity including the fluorescence of the protective film and the reflected light from the surface by a measurement unit; a protective film fluorescence intensity calculation step of removing the reflection intensity due to the pattern formed on the surface by subtracting the first reflection intensity measured in the pre-protective film formation measurement step from the second reflection intensity measured in the post-protective film formation measurement step and calculating the fluorescence intensity of the protective film; and a protective film thickness recognition step of recognizing the thickness of the protective film from the correlation data between the fluorescence intensity of the protective film and the thickness of the protective film obtained in advance and the calculated fluorescence intensity of the protective film. By including these steps, it becomes possible to accurately measure the thickness of the protective film formed on the surface of a substrate having a pattern on its surface.

[0011] In the method for measuring the thickness of the protective film according to the present invention, the measuring unit can function as an imaging unit. In the pre-protective film formation measurement step, the imaging unit images the surface of the substrate. In the post-protective film formation measurement step, the imaging unit images the surface of the protective film formed on the surface of the substrate. The first reflection intensity and the second reflection intensity are measured by the luminance of the pixels of the respective images acquired by the imaging unit, respectively, making it possible to shorten the measurement time compared to point measurement using a conventional sensor.

[0012] In the method for measuring the thickness of the protective film according to the present invention, in the pre-protective film formation measurement step and the post-protective film formation measurement step, the light source that irradiates the surface of the substrate is a white light source. This enables the light source to emit light of multiple wavelengths. By disposing a first filter that transmits only light of a specific wavelength between the light source and the substrate, it becomes possible to irradiate only the light of the desired wavelength onto the protective film from the light (light of multiple wavelengths) irradiated depending on the type of the protective film, light-absorbing material, etc.

[0013] In the method for measuring the thickness of the protective film according to the present invention, in the pre-protective film formation measurement step and the post-protective film formation measurement step, the light source that irradiates the surface of the substrate is a white light source. By disposing a second filter that transmits only light of a specific wavelength between the substrate and the measuring unit, in the post-protective film formation measurement step, the irradiation light from the light source is prevented from entering the measuring unit.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] The processing apparatus 1 shown in FIG. 1 is an apparatus for laser-processing a substrate 90 sucked and held on a chuck table 30 by a laser irradiation unit 12. The region on the +X direction side on the apparatus base 10 having the X-axis direction of the laser processing apparatus 1 as the longitudinal direction is a loading / unloading region where the substrate 90 is loaded and unloaded with respect to the chuck table 30, and the region on the -X direction side on the apparatus base 10 is a processing region where the substrate 90 sucked and held on the chuck table 30 by the laser irradiation unit 12 is laser-processed. Note that the processing apparatus 1 is not limited to a laser processing apparatus, and may be a cutting apparatus or the like capable of dicing the substrate 90 with a cutting blade.

[0016] The substrate 90 shown in FIGS. 1 and 2 is, for example, a circular silicon semiconductor wafer. On the surface 900 facing the upper side of the substrate 90, device chips 904 are formed in a grid-like region partitioned by a planned division line 902. And a predetermined pattern 909 is formed on the device chip 904. In FIGS. 1 and 2, the pattern 909 is schematically represented by a square shape formed at the corner of the device chip 904, but the shape is not limited thereto. That is, the substrate 90 is a substrate having a device pattern on the surface 900.

[0017] For example, the back surface 906 of the substrate 90 is adhered to the adhering surface (front surface) of the support tape 93. The outer peripheral portion of the support tape 93 is adhered to the annular frame 94. Thereby, the substrate 90 is supported by the annular frame 94 via the support tape 93, and becomes a work set 9 that can be handled using the annular frame 94. The center of the annular frame 94 and the center of the substrate 90 are substantially aligned. Note that the substrate 90 is not limited to the above example, and may be a single substrate without being a work set 9, and may be made of gallium arsenide, sapphire, gallium nitride, resin, ceramics, or silicon carbide other than silicon.

[0018] On the front side (+Y direction side) of the apparatus base 10, an input unit 100 for an operator to input processing conditions and the like for the laser processing apparatus 1 is provided. As shown in FIG. 1, a cassette mounting table 13 is installed at a corner on the +Y direction side of the apparatus base 10. The cassette mounting table 13 is movable up and down in the Z-axis direction by an elevating elevator (not shown) disposed below it. Then, with a cassette 14 containing a plurality of work sets 9 inside its shelves placed on the cassette mounting table 13, the cassette mounting table 13 is moved up and down by the elevating elevator, thereby adjusting the height position when taking in and out the target work set 9 from the cassette 14.

[0019] For example, in front of an opening (not shown) on the -Y direction side of the cassette 14 placed on the cassette mounting table 13 shown in FIG. 1, there is a push-pull 15 that pulls out the workpiece set 9 before processing from the cassette 14 and inserts the laser-processed and cleaned workpiece set 9 into the cassette 14.

[0020] For example, within the movable range of the push-pull 15 movable in the Y-axis direction, there is arranged a centering guide 16 consisting of a pair of guide rails that align the workpiece set 9 pulled out from the cassette 14 by the push-pull 15 to a certain position.

[0021] As shown in FIG. 1, the laser processing apparatus 1 includes a first transfer unit 17 that holds the workpiece set 9 centered by the centering guide 16 and transfers the workpiece set 9 to the coating table 700 of the protective film forming unit 70 or withdraws the workpiece set 9 from the coating table 700.

[0022] The first transfer unit 17 includes a holding pad 171 that holds the workpiece set 9 held by the centering guide 16 from above, and a moving mechanism 173 that moves the holding pad 171 up and down in the Z-axis direction (vertical direction) and rotates within the horizontal plane (within the X-axis Y-axis plane). The holding pad 171 attached to the lower surface of the tip of the turning arm 174 of the moving mechanism 173 has, for example, an H shape in plan view, and has four suction pads 176 on its lower surface that adsorb the annular frame 94 that supports the substrate 90. Each suction pad 176 communicates with a suction source such as a vacuum generating device (not shown) that generates suction force.

[0023] In a region on the -X direction side of the arrangement position of the first transfer unit 17 on the apparatus base 10, there are arranged a protective film forming unit 70 that forms a protective film on the surface 900 of the substrate 90, and a cleaning unit 74 that cleans the workpiece set 9 after laser processing. In the vicinity of the protective film forming unit 70 and the cleaning unit 74, there is provided a second transfer unit 18 that holds the work set 9 on which the protective film is formed by the protective film forming unit 70, and transfers the work set 9 to or from the chuck table 30, or transfers the work set 9 after laser processing from the chuck table 30 to the cleaning unit 74.

[0024] The second transfer unit 18 includes, for example, a holding pad 181 that holds the work set 9 suction-held on the chuck table 30 from above, and a moving mechanism 183 that moves the holding pad 181 up and down in the Z-axis direction (vertical direction) and rotates it within the horizontal plane (within the X-axis Y-axis plane). The holding pad 181 attached to the lower surface of the tip of the turning arm 184 of the moving mechanism 183 has, for example, an H shape in plan view, and has four suction disks 186 on its lower surface that adsorb the annular frame 94 that supports the substrate 90. Each suction disk 186 communicates with a suction source such as a vacuum generating device (not shown) that generates suction force.

[0025] The protective film forming unit 70 shown in FIG. 1 includes at least a coating table 700 that is housed in a casing 708 and sucks and holds the substrate 90, a rotating unit 702 including a motor and a rotating shaft that rotate the coating table 700, a protective film agent application nozzle 704 that can turn and move above the coating table 700 at a predetermined angle, and a plurality of clamping clamps 705 that are arranged at equal intervals in the circumferential direction around the coating table 700 and sandwich the annular frame 94. For example, the coating table 700 may be movable in the vertical direction by a lifting unit (not shown) composed of an air cylinder or the like. The lifting unit (not shown) raises the coating table 700 to position the coating table 700 at the height position for loading and unloading the substrate 90, and lowers the coating table 700 holding the substrate 90 to position the coating table 700 at the height position for forming the protective film within the casing 708.

[0026] The cleaning unit 74 shown in Fig. 1 includes at least a spinner table 740 that sucks and holds the substrate 90, a rotating unit 742 that rotates the spinner table 740, a cleaning nozzle 744 that can pivotally move above the spinner table 740 at a predetermined angle, and a clamping clamp 745 that is arranged in a plurality of circumferentially equidistant positions around the spinner table 740 and clamps the annular frame 94.

[0027] The chuck table 30, which is circular in plan view, has, for example, a flat holding surface 300 composed of a porous member or the like, and the holding surface 300 communicates with a suction source (not shown) such as a vacuum generator or an ejector mechanism. Further, around the chuck table 30, clamps 31 for clamping and fixing the annular frame 94 are arranged at equal intervals in the circumferential direction. As shown in Fig. 1, the chuck table 30 is surrounded by a cover 39 from the periphery and is rotatable about the Z-axis by a table rotation mechanism 33 connected to the lower surface side thereof. In addition, the chuck table 30 can reciprocate in the X-axis direction, which is the processing feed direction, and the Y-axis direction, which is the indexing feed direction, by means of an electric slider or the like arranged below it.

[0028] Above the movement path of the chuck table 30, an alignment unit 11 for detecting the division planned line 902 to be laser processed on the substrate 90 is arranged. The alignment unit 11 includes an imaging unit (not shown) that images the surface 900 of the substrate 90, and based on the image obtained by the imaging unit (not shown), the laser processing division planned line 902 can be detected by image processing such as pattern matching. The image obtained by the imaging unit (not shown) is displayed on the monitor 113 shown in Fig. 1.

[0029] The laser irradiation unit 12 has, for example, a cylindrical casing 120. The casing 120 extends horizontally in the Y-axis direction, and an irradiation head 122 is arranged at the tip of the casing 120. Inside the casing 120, a laser oscillator (not shown), such as a YAG pulse laser, is disposed. The laser beam emitted horizontally in the +Y direction from the laser oscillator (not shown) is reflected in the -Z direction by a mirror (not shown) and enters the condenser lens inside the irradiation head 122, and is condensed and irradiated onto the substrate 90 sucked and held by the chuck table 30. The height position of the condensing point of the laser beam can be adjusted in the Z-axis direction by a condensing point position adjusting means (not shown).

[0030] The laser processing apparatus 1 includes a light-emitting type light source 60 that irradiates the substrate 90 with light. The light source 60 is, for example, a white light source that can irradiate light in a wide wavelength range (ultraviolet, visible, and near-infrared). The light source 60, which is a white light source to save the trouble of switching the light source according to the measurement content shown in FIGS. 1 and 3, is disposed above the coating table 700 of the protective film forming unit 70, and is configured to irradiate obliquely from above the surface 900 of the substrate 90 of the work set 9 sucked and held by the coating table 700. On the optical path of the emitted light including the light having a wavelength absorbed by the light-absorbing material contained in the protective film 92 emitted from the light source 60, a condenser lens 603 for adjusting the focus of the emitted light is disposed. Note that, as the light source 60, a lamp that irradiates single-wavelength light such as halogen, tungsten, or mercury may be used.

[0031] Furthermore, in the present embodiment, a first filter 61 that transmits only light of a specific wavelength (for example, light having a wavelength of 435 nm or light having a wavelength of 365 nm) is disposed between the light source 60 and the substrate 90 sucked and held by the coating table 700. Specifically, the first filter 61 includes a filter changer of a wheel rotation type, and switches by rotating a plurality of filter members arranged in a circumferential manner on the filter ring of the filter changer, and makes the filter member positioned on the optical path a filter member that transmits light having a wavelength of 435 nm, for example, or a filter that transmits light having a wavelength of 365 nm.

[0032] For example, at a position above the coating table 700 on the opposite side across the center of the coating table 700 from the light source 60, light irradiates the surface 900 of the substrate 90, and a measurement unit 69 is provided to receive the reflected light reflected by the patterns 909 (see FIG. 2, not shown in FIG. 3) located at the respective X-axis and Y-axis coordinate positions formed on the surface 900 that is particularly required, and measure the first reflection intensity. Further, on the optical path of the light traveling from the surface 900 of the substrate 90 toward the measurement unit 69, for example, a second filter 68 that transmits only light of a specific wavelength (for example, light with a wavelength of 435 nm in the measurement step after forming the protective film described later), and a condenser lens 67 that condenses the light passing through the second filter 68 onto the light receiving surface of the measurement unit 69 are arranged. Note that the second filter 68 may be configured to include a filter changer like the first filter 61.

[0033] Note that the condenser lens 603 and the condenser lens 67 are each composed of a single lens or a combination lens. Also, the condenser lens 603 is configured to be drivable in the optical axis direction, for example, and may be able to adjust the focal point and the condensing diameter of the measurement light.

[0034] The measurement unit 69 in this embodiment can function as an imaging unit, for example. That is, the measurement unit 69 that functions as an imaging unit may be, for example, an area sensor camera having an imaging area capable of imaging the entire surface 900 of the substrate 90 sucked and held on the coating table 700, or an area sensor camera having an imaging area capable of imaging approximately 1 / 4 of the surface 900 of the substrate 90. However, for example, the measurement unit 69 may be a line sensor camera, and may include an imaging unit that photoelectrically converts the subject image formed by the reflected light traveling from the surface 900 of the substrate 90 through the optical system including the second filter 68, the condenser lens 67, etc. toward the measurement unit 69 and outputs image information.

[0035] The imaging unit of the measurement unit 69 is configured such that a plurality of light-receiving elements such as CCDs are arranged, for example, linearly. The imaging unit has an imaging region with a length greater than or equal to the radius of the substrate 90 because the length in its longitudinal direction is greater than or equal to the radius of the substrate 90. Then, for example, in the pre-protective film formation measurement step described later, the measurement unit 69 sequentially transmits the linear imaging images obtained successively as the coating table 700 that sucks and holds the substrate 90 rotates to the control unit 19 shown in FIG. 1. The imaging images are sequentially recorded in the storage medium of the control unit 19 so as to be able to form an imaging image in which the entire surface 900 of the substrate 90 is shown. Then, for example, when the coating table 700 finishes rotating 360 degrees, the control unit 19 displays the imaging image showing the entire surface of the substrate 90 on the monitor 113 shown in FIG. 1. Note that even if the measurement unit 69 functioning as an imaging unit is an area sensor camera having an imaging region capable of imaging 1 / 4 of the surface 900 of the substrate 90, an imaging image substantially the same as the above line sensor camera can be obtained.

[0036] Note that the measurement unit 69 does not function as an imaging unit and includes the above line sensor as a light-receiving unit. As the coating table 700 that sucks and holds the substrate 90 rotates 360 degrees, for example, in the pre-protective film formation measurement step, the first reflection intensity on the entire surface 900 of the substrate 90 (that is, at each X-axis Y-axis coordinate position) can be measured. In this case, the amount of light received by the line sensor varies depending on the first reflection intensity of each region in the X-axis Y-axis plane of the surface 900 of the substrate 90, and the measurement unit 69 converts the different amounts of received light into, for example, voltage signals and transmits them to the control unit 19 shown in FIG. 1.

[0037] As shown in FIG. 1, the laser processing apparatus 1 includes a control unit 19 that controls the entire apparatus. The control unit 19 is composed of a CPU that performs arithmetic processing according to a control program and a storage medium such as a memory. It is electrically connected to a rotating unit 702 that rotates a coating table 700 of a protective film forming unit 70 and a moving mechanism 173 of a first transfer unit 17 via a wired or wireless communication path (not shown). Under the control of the control unit 19, the movement control by the first transfer unit 17 that sucks and holds the substrate 90 and the rotation control of the substrate 90 sucked and held by the coating table 700 are controlled. Further, a correlation graph G showing the correlation data between the fluorescence intensity of the protective film and the thickness of the protective film, which was acquired in advance and is shown in FIG. 4, is stored in the storage medium of the control unit 19. Specifically, for example, when the motor, which is a rotation drive source constituting the rotation unit 702 of the protective film forming unit 70, is a servo motor, the rotary encoder of the servo motor is connected to the control unit 19 that also functions as a servo amplifier. After an operation signal is supplied from the output interface of the control unit 19 to the servo motor, the rotation speed of the servo motor is output as an encoder signal to the input interface of the control unit 19. Then, the control unit 19 that receives the encoder signal sequentially recognizes the rotation angle of the coating table 700 based on the rotation angle of the servo motor, and thereby can sequentially recognize the direction of the division planned line 902 of the substrate 90 sucked and held by the coating table 700 and the direction of the substrate 90 in the X-axis Y-axis plane, etc.

[0038] Next, the operations of each component of the laser processing apparatus 1 and each step of the method for measuring the thickness of the protective film according to the present invention, which measures the thickness of the protective film formed on the surface 900 of the substrate 90 in the laser processing apparatus 1, when the substrate 90 is laser processed by the laser processing apparatus 1 shown in FIG. 1 will be described.

[0039] (Unloading from the cassette of the work set and loading onto the coating table) First, a cassette 14 containing a plurality of work sets 9 shown in FIG. 1 is placed on a cassette mounting table 13, and then the height of the cassette 14 is adjusted by an elevating elevator. Next, a push-pull 15 moves in the +Y direction and enters the cassette 14, and grips an annular frame 94 of the work set 9 placed on the target shelf. By the push-pull 15, one work set 9 is pulled out from the cassette 14, and the annular frame 94 is placed on a centering guide 16 to perform centering (detection of the center position) of the work set 9.

[0040] By a moving mechanism 173 of a first transfer unit 17, a holding pad 171 is positioned above the annular frame 94 on the centering guide 16, and the center of the holding pad 171 and the center of the work set 9 are substantially aligned. Further, the holding pad 171 descends, and four suction pads 176 come into contact with the upper surface of the annular frame 94 to perform suction.

[0041] The holding pad 171 holding the work set 9 shown in FIG. 1 rotates and moves to be positioned above a coating table 700 of a protective film forming unit 70, and the holding pad 171 descends to place the work set 9 on the holding surface of the coating table 700. The coating table 700 sucks and holds a substrate 90 with its surface 900 facing upward on a flat holding surface, and the annular frame 94 separated from the holding pad 171 is clamped and fixed by a clamping clamp 705.

[0042] (1) Pre-measurement step before protective film formation In the method for measuring the thickness of the protective film according to the present invention, first, a pre-protective film formation measurement step is performed in which light is irradiated onto the surface 900 of the substrate 90 in a state where the protective film is not formed, and the first reflection intensity from the surface 900 (that is, the first reflection intensity from each X-axis Y-axis coordinate position of the surface 900) is measured. In the pre-protective film formation measurement step, first, the measurement light emitted from the light source 60 shown in FIG. 3 is condensed by the condenser lens 603 and then passes through the first filter 61. The wavelength of the measurement light that has passed through the first filter 61 is, for example, 435 nm, and it is incident on the surface 900 of the substrate 90 shown in FIG. 1. The reason for setting the wavelength of the measurement light incident on the surface 900 of the substrate 90 to a single wavelength of 435 nm is to make the fluorescence of the protective film in the post-protective film formation measurement step described later, for example, 435 nm, and to match this.

[0043] The reflected light with a wavelength of 435 nm from the surface 900 of the substrate 90 shown in FIGS. 1 and 2, that is, from the pattern 909 formed at each X-axis Y-axis coordinate position of the surface 900, passes through the second filter 68 set to transmit only light with a wavelength of 435 nm in advance, is captured by the condenser lens 67, and is incident on the imaging unit composed of the light receiving element of the measurement unit 69 that functions as an imaging unit in the present embodiment. While the measurement light with a wavelength of 435 nm is incident on the surface 900 of the substrate 90 in this way, as described above, for example, when the coating table 700 shown in FIG. 1 finishes rotating 360 degrees by the rotating unit 702, the control unit 19 can form an imaging image showing the entire surface of the surface 900 of the substrate 90. Note that the measurement unit that can function as an imaging unit is a monochrome camera in the present embodiment, but it may also be a color camera.

[0044] The intensity measurement unit 193 of the control unit 19 shown in FIG. 1 executes a program for measuring the first reflection intensity from the formed imaging image. The captured image is, for example, a collection of pixels of a predetermined size where the luminance value is represented in 8-bit gradation, that is, 256 levels from 0 to 255. One pixel has less brightness as the luminance value approaches 0, approaching black, and has more brightness as the luminance value approaches 255, approaching white. For each pixel of the formed captured image, that is, the smaller the amount of light of the reflected light incident on each pixel of the CCD of the imaging unit of the measurement unit 69, the closer the luminance value of that pixel approaches 0, approaching black, and the first reflection intensity becomes a small value.

[0045] When the substrates 90 of the plurality of work sets 9 stored in a shelf-like manner in the cassette 14 are substrates of the same lot, the pre-protective film formation measurement step is performed only for the substrate 90 (the first substrate 90) of the work set 9 to be processed first. The intensity measurement unit 193 creates a first reflection intensity data table in which the respective X-axis and Y-axis coordinate positions in the X-axis Y-axis plane coordinate system parallel to the surface 900 of the substrate 90 in the captured image are associated with the measured first reflection intensities at the respective X-axis and Y-axis coordinate positions. Then, when processing the second and subsequent work sets 9, by using this first reflection intensity data table, it may not be necessary to perform this pre-protective film formation measurement step. This first reflection intensity data table is stored in the storage medium of the control unit 19 for use in the post-protective film formation measurement step described later.

[0046] In principle, the X-axis and Y-axis coordinate positions on the coating table 700 of the surface 900 of the substrate 90 of the work set 9 are determined based on the center of the holding surface of the coating table 700 that can be constantly grasped by the control unit 19 because the work set 9 is sucked and held in a state where its center is substantially aligned with the coating table 700 by the first transfer unit 17 whose movement is controlled by the control unit 19 after the work set 9 is centered by the centering guide 16, and can be constantly grasped together with the rotation angle of the coating table 700. When notches or orientation flats are formed on the substrate 90, these may be used to recognize the respective X-axis and Y-axis coordinate positions of the surface 900 of the substrate 90 in the captured image.

[0047] Also, when processing the second and subsequent work sets 9 including the substrate 90 of the same lot (type) as the first one, when the second and subsequent work sets 9 are held on the coating table 700, the orientation of the second substrate 90 may deviate from the orientation of the first substrate 90 on the coating table 700 when forming the first reflection intensity data table. In this case, in the pre-protective film formation measurement step, after the measurement unit 69 forms an imaging image in which the surface 900 of the second substrate 90 is reflected, using the imaging image of the substrate 90 of the first work set 9 and the imaging image of the substrate 90 of the second work set 9, pattern matching using the pattern 909 formed on the substrate 90, and / or when notches or orifices are formed on the substrate 90, matching using these is performed to recognize the deviation amount (the deviation amount in the X-axis Y-axis coordinate system, or the θ deviation amount), and a correction value based on the deviation amount is obtained. Then, the correction value for the deviation is added to the first reflection intensity data table that associates each X-axis Y-axis coordinate position of the substrate 90 on the coating table 700 created in the pre-protective film formation measurement step for the first work set 9 with each first reflection intensity to correct the deviation, and subsequent steps such as the post-protective film formation measurement step described later may be performed. Note that the pre-protective film formation measurement step is performed every time the lot (type) of the substrate 90 to be processed changes. This is because the material and the configuration of the pattern 909 differ depending on the type of the substrate 90, so the first reflection intensity changes.

[0048] (2) Protective film formation step After completion of the measurement step before forming the protective film, a protective film containing a light-absorbing material is then formed on the surface 900 of the substrate 90 sucked and held by the coating table 700 shown in FIG. 1. Specifically, a protective film agent coating nozzle 704 that communicates with a protective film agent supply source (not shown) and drops and injects a liquid protective film agent downward is positioned above the center of the substrate 90, and a predetermined amount of the protective film agent is dropped onto the center of the surface 900. Thereafter, it is performed by spin coating in which the coating table 700 and the work set 9 are rotated. Due to the centrifugal force generated by the rotation of the coating table 700, the protective film agent is applied to the entire surface 900. When a predetermined amount of the protective film agent is applied, the dropping of the protective film agent is terminated. After applying a predetermined amount of the protective film agent to the surface 900 of the substrate 90, the protective film agent is dried and solidified by rotating the coating table 700 to form the protective film 92 shown in FIG. 3 to a desired thickness. Note that, for example, the protective film agent coating nozzle 704 may be swung and moved so as to pass above the center of the substrate 90 and reciprocate at a predetermined angle above the substrate 90, so that the protective film agent spreads and is applied to the entire surface 900 of the substrate 90 of the work set 9 rotated by the coating table 700, and the protective film 92 covering the entire surface 900 may be formed. The formed protective film 92 prevents debris in laser processing from adhering to the surface 900 of the substrate 90.

[0049] Examples of the liquid protective film agent include polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol having 5 or more ethyleneoxy repeating units, polyethylene oxide, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, polyacrylic acid, polyvinyl alcohol polyacrylic acid block copolymer, polyvinyl alcohol polyacrylate ester block copolymer, polyglycerin, etc. These can be used alone or in combination of two or more. The protective film agent in this embodiment is, for example, the product name HogoMax manufactured by DISCO Corporation, which is water-soluble.

[0050] The liquid protective film agent contains a light absorber that absorbs light in a predetermined wavelength range (for example, a wavelength range of 250 nm or more and 450 nm or less). As the light absorber, for example, plastic additives such as benzophenone-based, benzotriazole-based, triazine-based, and benzoate-based are used. Note that the light absorber absorbs light with the wavelength of the laser beam when, for example, laser processing is performed on the substrate 90.

[0051] (3) Post-protective film formation measurement step As shown in FIG. 3, after the protective film 92 is formed on the surface 900 of the substrate 90, excitation light having a wavelength at which the light absorber fluoresces is irradiated toward the protective film 92, and the fluorescence of the protective film 92 and the pattern 909 (see FIG. 2) formed on the surface 900 of the substrate 90 by the measuring unit 69 are measured. A post-protective film formation measurement step of measuring a second reflection intensity including reflected light reflected from the pattern 909 when the fluorescence of the protective film 92 is incident thereon is performed.

[0052] For example, first, the coating table 700 is rotated by a predetermined angle and stopped under the control of the rotation unit 702 by the control unit 19 shown in FIG. 1 so that the orientation of the substrate 90 in the X-axis Y-axis plane at the time of forming the imaging image in the pre-protective film formation measurement step coincides with the orientation of the substrate 90 after the formation of the protective film 92.

[0053] For example, the first filter 61 in which the filter member is switched to a filter member different from the filter member used in the pre-protective film formation measurement step (a filter member that transmits light with a wavelength of 365 nm) by a filter changer is transmitted after the excitation light emitted from the light source 60 is condensed by the condenser lens 603. The excitation light transmitted through the first filter 61 is, for example, continuous light having a single wavelength of 365 nm, and is incident on the protective film 92 formed on the surface 900 of the substrate 90. Note that although it depends on the type of the light absorber contained in the protective film 92, the excitation light is continuous light in order to suppress the modification of the protective film 92, and it is preferable to use light having a wavelength at which the fluorescence intensity of the protective film 92 becomes the maximum.

[0054] When the irradiated excitation light is absorbed by the light absorber of the protective film 92, the light absorber in the ground state is excited and becomes an unstable state with high molecular energy. Then, after the light absorber falls to the relaxed singlet state, it emits energy while emitting light with a longer wavelength than the excitation light emitted from the light source 60 (for example, light with a wavelength of 435 nm) and returns to the ground state. The light emitted when returning to this ground state is fluorescence. The fluorescence with a wavelength of 435 nm passes through the second filter 68 shown in FIG. 3 that is set to transmit only light with a wavelength of 435 nm in advance, is captured by the condenser lens 67, and in this embodiment, enters the imaging unit composed of the light receiving element of the measurement unit 69 that functions as an imaging unit. Note that the excitation light with a wavelength of 365 nm from the light source 60 is blocked by the second filter 68 and does not enter the imaging unit of the measurement unit 69.

[0055] Since the pattern 909 (see FIG. 2) is formed on the surface 900 of the substrate 90, the fluorescence of the protective film 92 that enters the pattern 909 and the reflected light with a wavelength of 435 nm reflected by the pattern 909 also pass through the second filter 68, are captured by the condenser lens 67, and enter the imaging unit composed of the light receiving element of the measurement unit 69.

[0056] In this way, while the excitation light with a wavelength of 365 nm is incident on the protective film 92 formed on the surface 900 of the substrate 90, as described above, for example, when the coating table 700 finishes rotating 360 degrees by the rotating unit 702, the measurement unit 69 can form the imaging image 99 shown in FIG. 5 showing the entire surface of the protective film 92 on the substrate 90.

[0057] The intensity measurement unit 193 of the control unit 19 shown in FIG. 1 executes a program for measuring the second reflection intensity including the fluorescence of the protective film 92 and the reflected light that enters the pattern 909 formed on the surface 900 and is reflected by the pattern 909 from the imaging image 99 formed in this step. First, in the captured image 99, the second reflection intensity increases proportionally with the thickness of the protective film 92 (see FIG. 3) formed on the surface 900 of the substrate 90. This is because when the thickness of the protective film 92 increases, the amount of light-absorbing material contained in the protective film 92 also increases.

[0058] The intensity measurement unit 193 shown in FIG. 1 creates a second reflection intensity data table in which the X-axis and Y-axis coordinate positions of the protective film 92 formed on the surface 900 of the substrate 90 in the captured image 99 are respectively associated with the measured second reflection intensity (pixel luminance) at each X-axis and Y-axis coordinate position. The second reflection intensity data table created from the captured image 99 at this point in time is such that the reflected light with a wavelength of 435 nm, which is incident on the pattern 909 existing at each X-axis and Y-axis coordinate position of the surface 900 due to the fluorescence of the protective film 92 and is reflected by the pattern 909, also enters the imaging unit of the measurement unit 69 shown in FIG. 3 and is created. Therefore, the film thickness of the protective film 92 cannot be accurately measured. In FIG. 5, the thick region 923 of the protective film 92 shown in FIG. 3 on the surface 900 of the substrate 90 is shown with a white filter (haze) applied.

[0059] (4) Protective film fluorescence intensity calculation step Therefore, a protective film fluorescence intensity calculation step is performed to calculate the fluorescence intensity of the protective film 92 by removing the reflection intensity due to the pattern 909 formed on the surface 900 by subtracting the first reflection intensity measured in the measurement step before protective film formation from the second reflection intensity measured in the measurement step after protective film formation.

[0060] The control unit 19 shown in FIG. 1 includes a calculation unit 198 that executes a protective film fluorescence intensity calculation program. The calculation unit 198 uses the captured image 99 shown in FIG. 5 to subtract the first reflection intensity measured in the measurement step before forming the protective film from the second reflection intensity measured in the measurement step after forming the protective film. That is, a post-removal captured image 997 shown in FIG. 6 is formed by subtracting the first reflection intensity at each corresponding X-axis Y-axis coordinate position from the measured second reflection intensity at each X-axis Y-axis coordinate position in the captured image 99. In the post-removal captured image 997, only the fluorescence intensity of the protective film 92 (see FIG. 3) is displayed. Therefore, the calculation unit 198 calculates / stores the fluorescence intensity of the protective film 92 at each coordinate position in the X-axis Y-axis coordinate plane of the entire surface of the protective film 92 one by one.

[0061] (4) Protective film thickness recognition step Next, for example, the calculation unit 198 shown in FIG. 1 uses the correlation graph G shown in FIG. 4 that is pre-input and stored in a storage medium such as a memory, and the fluorescence intensity of the protective film 92 calculated using the post-removal captured image 997 shown in FIG. 6 in the protective film fluorescence intensity calculation step, to recognize the respective thicknesses of the protective film 92 formed on the surface 900 of the substrate 90 at the X-axis Y-axis coordinate positions.

[0062] The correlation graph G shown in FIG. 4 is a plot of the correlation data between the fluorescence intensity of a pre-acquired protective film (for example, the same type of protective film formed with HogoMax used in this embodiment) and the thickness of the protective film. In the correlation graph G, the horizontal axis represents the fluorescence intensity of the protective film (unit: lx), and the vertical axis represents the thickness of the protective film (unit: μm). As shown in the correlation graph G, for example, if the fluorescence intensity of the protective film is 150 lx, the thickness of the protective film is 1 μm.

[0063] The above correlation graph G is obtained, for example, by experiments conducted in advance. That is, on, for example, a plurality of dummy wafers on which no pattern is formed, the protective film 92 (for example, a protective film composed of HogoMax) to be formed on the current substrate 90 and similar protective films were formed with different thicknesses. Then, using a focused ion beam (FIB) measurement device or the like, the exact thickness of each was measured, and light with a predetermined wavelength (for example, a wavelength of 365 nm) was irradiated from a light source onto the protective films with respective thicknesses, and the fluorescence intensity of each protective film was measured. It is preferable that the light source used and the light source 60 (a white light source 60 in this embodiment) provided in the laser processing apparatus 1 actually have the same specifications.

[0064] Note that, as correlation data between the fluorescence intensity of the protective film obtained in advance and the thickness of the protective film, graph-form data was used, but it is not limited to this configuration. The correlation data may be, for example, table-form data showing the correspondence between the thickness of the protective film and the fluorescence intensity of the protective film.

[0065] For example, assume that the desired thickness of the protective film 92 (see FIG. 3) formed on the surface 900 of the substrate 90 shown in FIG. 6 is 1 μm. And the region in the X-axis Y-axis coordinate system without a white filter on the surface 900 of the substrate 90 in the post-removal imaging image 997 of FIG. 6 has a fluorescence intensity calculated in the protective film fluorescence intensity calculation step of, for example, 150 lx, and is recognized as having a desired thickness of 1 μm from the correlation graph G shown in FIG. 4. The region 923 with a white filter applied compared to the region with a thickness of 1 μm has a fluorescence intensity calculated in the protective film fluorescence intensity calculation step of, for example, 300 lx, and the calculation unit 198 recognizes from the correlation graph G shown in FIG. 4 that the thickness is 2 μm, which is 1 μm thicker than the desired thickness of 1 μm.

[0066] For example, with regard to the desired thickness of the protective film 92, a pre-set upper limit threshold value and a lower limit threshold value are set in advance. When the thickness of the protective film 92 is equal to or greater than the lower limit threshold value and equal to or less than the upper limit threshold value, it is determined to be within a predetermined range as a protective film with an appropriate thickness. When the thickness of the protective film 92 is less than the lower limit threshold value or greater than the upper limit threshold value, it is determined to be outside the predetermined range as a protective film that is too thick or too thin. Further, when the area of the protective film 92 recognized as having a thickness outside the predetermined range (too thick or too thin) becomes equal to or greater than the allowable value, it may be determined that an inappropriate protective film 92 is formed on the surface 900 of the substrate 90.

[0067] In addition, in the protective film thickness recognition step, when it is determined that an inappropriate thickness protective film is formed on the surface 900 of the substrate 90, the work set 9 shown in FIG. 1 is, for example, transported from the coating table 700 by the first transport unit 17 to the spinner table 740 of the cleaning unit 74, suction-held by the spinner table 740, and the annular frame 94 is clamped and fixed by the clamping clamp 745. Then, for example, a cleaning nozzle 744 that communicates with a cleaning water supply source (not shown) and injects cleaning water downward rotates and moves back and forth at a predetermined angle above the substrate 90 so as to pass above the center of the substrate 90, thereby cleaning and removing the water-soluble protective film 92 with an inappropriate thickness on the work set 9 rotated by the spinner table 740. Thereafter, again, the steps after the protective film formation step described above are implemented.

[0068] (Laser processing on a substrate with a protective film of appropriate thickness) The work set 9 with the protective film 92 of appropriate thickness formed on the surface 900 of the substrate 90 is transported from the coating table 700 shown in FIG. 1 to the chuck table 30 by the second transport unit 18. Then, the chuck table 30 suction-holds the substrate 90 with the protective film 92 facing upward on a flat holding surface, and the annular frame 94 with the holding pads 181 separated is clamped and fixed by the clamp 31.

[0069] Next, the chuck table 30 is sent in the -X direction (forward direction), and the alignment unit 11 detects the position of the planned division line 902 that serves as a reference for irradiating the laser beam. Then, the chuck table 30 is indexed and fed in the Y-axis direction, and alignment in the Y-axis direction is performed between the planned division line 902 for irradiating the laser beam and the irradiation head 122 of the laser irradiation unit 12.

[0070] Furthermore, the height position of the condensing point of the laser beam condensed by a condensing lens (not shown) is adjusted to, for example, the height position of the surface 900 of the substrate 90. Then, the laser oscillator oscillates a laser beam having a wavelength that is absorbable by the substrate 90, and the laser beam is condensed and irradiated onto the planned division line 902.

[0071] Also, the substrate 90 is sent in the -X direction, which is the forward direction, at a predetermined processing feed rate, and the laser beam is irradiated onto the surface 900 of the substrate 90 along the planned division line 902, so that the substrate 90 is ablated from the surface 900 toward the back surface 906, and a processing groove for cutting the substrate 90, for example, is formed along the planned division line 902. Note that the processing groove may be a half-cut groove. Here, since an absorptive material that absorbs light of the wavelength of the laser beam is added to the protective film 92, the protective film 92 is also removed from above the planned division line 902 during the laser processing along with the processing of the substrate 90. For this reason, due to the pressure of the vapor of the thermal decomposition products of the substrate 90 or the like, the protective film 92 is not peeled off, debris is generated on the planned division line 902 shown in FIG. 1, but no debris adheres to the surface of the device chip 904 due to the protective film 92.

[0072] When the substrate 90 travels in the -X direction to a predetermined position where the irradiation of the laser beam along the division planned line 902 is completed, the irradiation of the laser beam is stopped. Further, the chuck table 30 is indexed and fed in the Y-axis direction by a predetermined distance so that the position directly below the condensing point of the irradiation head 122 is positioned on the next target division planned line 902. Then, the substrate 90 is processed and fed in the +X direction which is the return direction, and the substrate 90 is laser processed along the division planned line 902 in the same manner as the laser beam irradiation in the forward direction. Then, by sequentially performing the same laser processing while indexing and feeding the chuck table 30 in the Y-axis direction by the interval between adjacent division planned lines 902, the substrate 90 is cut along all the division planned lines 902 extending in the X-axis direction.

[0073] Furthermore, the chuck table 30 is rotated 90 degrees and the same laser processing is performed, so that all the division planned lines 902 are cut both vertically and horizontally and the substrate 90 is divided into device chips 904.

[0074] Thereafter, the work set 9 in which the substrate 90 is divided into device chips 904 is conveyed from the chuck table 30 to the cleaning unit 74 by the second conveyance unit 18, and the protective film 92 is cleaned and removed. Further, the cleaned work set 9 is accommodated in the cassette 14 by the first conveyance unit 17 and the push-pull 15.

[0075] As described above, the method for measuring the thickness of the protective film 92 formed on the surface 900 of the substrate 90 having the pattern 909 on the surface 900 according to the present invention includes: a pre-protective film formation measurement step of irradiating light onto the surface 900 of the substrate 90 in a state where the protective film is not formed and measuring the first reflection intensity of the reflected light from the surface 900; a protective film formation step of forming the protective film 92 containing an absorbent on the surface 900; a post-protective film formation measurement step of irradiating excitation light having a wavelength at which the absorbent fluoresces toward the protective film 92 and measuring the second reflection intensity including the fluorescence of the protective film 92 and the reflected light from the surface 900 by the measurement unit 69; a protective film fluorescence intensity calculation step of removing the reflection intensity due to the pattern 909 formed on the surface 900 by subtracting the first reflection intensity measured in the pre-protective film formation measurement step from the second reflection intensity measured in the post-protective film formation measurement step and calculating the fluorescence intensity of the protective film 92; and a protective film thickness recognition step of recognizing the thickness of the protective film 92 from the correlation data between the fluorescence intensity and the thickness of the protective film acquired in advance and the calculated fluorescence intensity of the protective film 92. By including these steps, it becomes possible to accurately measure the thickness of the protective film 92 formed on the surface 900 of the substrate 90 having the pattern 909 on the surface 900.

[0076] In the method for measuring the thickness of the protective film according to the present invention, the measurement unit 69 can function as an imaging unit. The pre-protective film formation measurement step involves imaging the surface 900 of the substrate 90 by the imaging unit 69, and the post-protective film formation measurement step involves imaging the surface of the protective film 92 formed on the surface 900 of the substrate 90 by the imaging unit 69. The first reflection intensity and the second reflection intensity are measured respectively based on the luminance of the pixels of the respective images acquired by the imaging unit 69, making it possible to shorten the measurement time compared to the prior art.

[0077] In the method for measuring the thickness of the protective film according to the present invention, in the pre-protective film formation measurement step and the post-protective film formation measurement step, the light source 60 that irradiates the surface 900 of the substrate 90 is a white light source 60. Thus, the light source 60 can emit light of a plurality of wavelengths, and by disposing a first filter 61 that transmits only light of a specific wavelength between the light source 60 and the substrate 90, it becomes possible to irradiate only the light of the desired wavelength onto the protective film 92 from the light (light of a plurality of wavelengths) irradiated according to the type of the protective film, light-absorbing material, etc.

[0078] In the method for measuring the thickness of the protective film according to the present invention, in the pre-protective film formation measurement step and the post-protective film formation measurement step, the light source 60 that irradiates the surface 900 of the substrate 90 is a white light source 60. By disposing a second filter 68 that transmits only light of a specific wavelength between the substrate 90 and the measurement unit 69, in the post-protective film formation measurement step, the irradiated light from the light source 60 is prevented from entering the measurement unit 69.

[0079] It goes without saying that the method for measuring the thickness of the protective film according to the present invention is not limited to the above-described embodiment, and may be implemented in various different forms within the scope of its technical idea. Also, each component of the laser processing apparatus 1 used when implementing the method for measuring the thickness of the protective film can be appropriately changed within the range where the effects of the present invention can be exhibited.

Explanation of Reference Numerals

[0080] 9: Workset 90: Substrate 900: Surface of substrate 902: Predetermined division line 904: Device chip 909: Pattern 906: Back surface of substrate 93: Support tape 94: Annular frame 92: Protective film 1: Laser processing apparatus 10: Apparatus base 100: Input unit 13: Cassette mounting table 14: Cassette 15: Push-pull 16: Centering guide 17: First transfer unit 171: Holding pad 173: Moving mechanism 174: Swivel arm 176: Suction plate 18: Second Transfer Unit 181: Holding Pad 183: Moving Mechanism 184: Swivel Arm 186: Suction Pad 70: Protective Film Forming Unit 700: Coating Table 704: Protective Film Agent Application Nozzle 702: Rotating Part 705: Clamping Clamp 74: Cleaning Unit 740: Spinner Table 742: Rotating Part 744: Cleaning Nozzle 745: Clamping Clamp 30: Chuck Table 300: Holding Surface 31: Clamp 33: Table Rotation Mechanism 39: Cover 11: Alignment Unit 113: Monitor 12: Laser Irradiation Unit 120: Casing 122: Irradiation Head 60: Light Source (White Light Source) 603: Condensing Lens 61: First Filter 67: Condensing Lens 68: Second Filter 69: Measuring Unit 19: Control Unit 193: Intensity Measuring Unit 198: Calculation Unit G: Graph showing the correlation data between the fluorescence intensity and the thickness of the protective film obtained in advance

Claims

1. A method for measuring the thickness of a protective film formed on a surface of a substrate having a pattern on the surface, comprising: a pre-protective film measurement step of irradiating light onto the surface of the substrate in a state where the protective film is not formed and measuring a first reflection intensity of reflected light from the surface; a protective film formation step of forming the protective film containing an absorbent on the surface; a post-protective film measurement step of irradiating excitation light having a wavelength at which the absorbent fluoresces toward the protective film and measuring a second reflection intensity including fluorescence of the protective film and reflected light from the surface by a measurement unit; a protective film fluorescence intensity calculation step of removing the reflection intensity due to the pattern formed on the surface by subtracting the first reflection intensity measured in the pre-protective film measurement step from the second reflection intensity measured in the post-protective film measurement step, and calculating the fluorescence intensity of the protective film; a protective film thickness recognition step of recognizing the thickness of the protective film from correlation data between the fluorescence intensity of the protective film and the thickness of the protective film obtained in advance and the calculated fluorescence intensity of the protective film; When measuring the first reflection intensity of a plurality of substrates in the pre-protective film measurement step, when there is a displacement in the position of the substrate between the first substrate and the second and subsequent substrates, a correction value for the displacement is obtained; Before the post-protective film measurement step, correcting the first reflection intensity data table of the second and subsequent substrates by the correction value; A method for measuring the thickness of a protective film.

2. The measurement unit can function as an imaging unit; the pre-protective film measurement step includes imaging the surface of the substrate by the imaging unit; the post-protective film measurement step includes imaging the surface of the protective film formed on the surface of the substrate by the imaging unit; The method for measuring the thickness of a protective film according to claim 1, wherein the first reflection intensity and the second reflection intensity are respectively measured by the luminance of pixels of the respective images acquired by the imaging unit.

3. The light source for irradiating light onto the surface of the substrate in the pre-protective film measurement step and the post-protective film measurement step is a white light source; The method for measuring the thickness of a protective film according to claim 1 or claim 2, wherein a first filter that transmits only light of a specific wavelength is disposed between the light source and the substrate.

4. In the measurement step before forming the protective film and the measurement step after forming the protective film, the light source that irradiates light onto the surface of the substrate is a white light source. The method for measuring the thickness of a protective film according to claim 1, claim 2, or claim 3, characterized in that a second filter that transmits only light of a specific wavelength is disposed between the substrate and the measurement unit.

Images