JP2024036204A - Substrate processing equipment and position measurement method - Google Patents

Abstract

To provide a technique for measurement by a measuring instrument, enabling stable detection of a location of a substrate.SOLUTION: A substrate processing system comprises a holder for holding a substrate, a measuring instrument for measuring a relative distance with the substrate, the measuring instrument being provided in a posture facing the substrate held by the holder, a mover for changing a relative position of the measuring instrument and the substrate, and a controller for controlling the mover, the measuring instrument being connected thereto. The measuring instrument detects light reflected on a surface of the substrate with a white confocal method in which a different focal distance is set for each of a plurality of wavelengths. The controller compares a reflected-light receiving quantity with a threshold held in advance, and when the light receiving quantity is less than the threshold, causes the mover to change the relative position and calculates then a position of the substrate using the relative distance measured by the measuring instrument.SELECTED DRAWING: Figure 8

Description

The present disclosure relates to a substrate processing apparatus and a position measurement method.

Patent Document 1 discloses a bonding device that includes an upper chuck that sucks an upper substrate from above and a lower chuck that sucks a lower substrate from below, and that bonds two substrates facing each other. . When bonding substrates, the bonding device pushes down the center of the substrate on the upper chuck so that it comes into contact with the center of the substrate on the lower chuck, bonds the centers of the two substrates together by intermolecular force, and moves this bonding area away from the center. Spread it to the outer edge.

This type of bonding apparatus includes a plurality of measuring devices on the upper chuck to measure the position of the substrate, and recognizes the progress of bonding by measuring the position of the substrate when it is separated from the upper chuck.

Japanese Patent Application Publication No. 2015-095579

The present disclosure provides a technique that can more stably detect the position of a substrate in measurement using a measuring instrument.

According to one aspect of the present disclosure, a holding part that holds a substrate, a measuring device provided at a position facing the substrate held by the holding part and measuring a relative distance with the substrate, and the measuring device A moving part that displaces the relative position with respect to the substrate, and a control part to which the measuring instrument is connected and controlling the moving part, the measuring instrument being set to different focal lengths for each of the plurality of wavelengths. The control section detects the reflected light reflected from the surface of the substrate using a white confocal method, and compares the received amount of the reflected light with a threshold value held in advance, and the control unit compares the received amount of the reflected light with the threshold value. Provided is a substrate processing apparatus that displaces the relative position by the moving unit and then calculates the position of the substrate using the relative distance measured by the measuring device.

According to one aspect, the position of the substrate can be detected more stably in measurement using a measuring device.

FIG. 2 is a side view showing an example of a first substrate and a second substrate. FIG. 2 is a plan view showing an example of a joining module according to an embodiment. FIG. 4 is a side view of the joining module of FIG. 3; FIG. 3 is a cross-sectional view showing an example of an upper chuck and a lower chuck. 3 is a flowchart illustrating an example of a substrate processing method. FIG. 6(A) is a side view showing an example of the operation in step S102 of FIG. FIG. 6(B) is a side view showing the operation following FIG. 6(A). FIG. 6(C) is a side view showing the operation following FIG. 6(B). FIG. 7(A) is a cross-sectional view showing an example of the operation in step S103 of FIG. FIG. 7(B) is a cross-sectional view showing an example of the operation in step S104 of FIG. FIG. 7(C) is a cross-sectional view showing the operation following FIG. 7(B). FIG. 3 is a cross-sectional view showing a plurality of displacement sensors provided on the upper chuck. FIG. 9A is a diagram showing when the displacement sensor detects red color and a graph showing a state where the reflectance of red color is low. FIG. 9(B) is a diagram showing when the displacement sensor detects green color and a graph showing a state where the green reflectance is low. FIG. 9C is a diagram showing when the displacement sensor detects blue color and a graph showing a state where the blue reflectance is low. FIG. 10A is a diagram showing a configuration for displacing the relative positions of the displacement sensor and the upper wafer. FIG. 10(B) is a diagram showing another configuration for displacing the relative positions of the displacement sensor and the upper wafer. 3 is a flowchart showing measurement processing in a substrate processing method. FIG. 12(A) is a graph showing the relationship between the initial relative position of the displacement sensor and the upper wafer and the amount of received reflected light. FIG. 12(B) is a graph showing the relationship between the displacement of the relative position of the displacement sensor and the upper wafer and the amount of received reflected light. FIG. 12C is a graph showing the relationship between the relative position of the displacement sensor and the upper wafer after the displacement and the amount of reflected light received. 7 is a flowchart illustrating measurement processing of a substrate processing method according to a first modification. It is a flowchart which shows the measurement process of the substrate processing method based on the 2nd modification. FIG. 15(A) is a schematic diagram showing a peeling device according to the second embodiment. FIG. 15(B) is a schematic diagram showing a thickness measuring device according to the third embodiment.

Hereinafter, embodiments for implementing the present disclosure will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and redundant explanations may be omitted. Note that the X-axis direction, Y-axis direction, and Z-axis direction used in the following description are axes that intersect perpendicularly to each other, the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction. be.

As the substrate processing apparatus according to the first embodiment, a bonding apparatus for bonding two substrates to produce a bonded substrate will be described as an example. As shown in FIG. 1, at least one of the two substrates (first substrate W1, second substrate W2) is a substrate in which a plurality of electronic circuits are formed on a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer. It is. One of the first substrate W1 and the second substrate W2 may be a bare wafer on which no electronic circuit is formed. The compound semiconductor wafer is, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer, although it is not particularly limited.

The first substrate W1 and the second substrate W2 are formed into disks having substantially the same shape (same diameter). As shown in FIG. 3, the bonding apparatus 1 places the second substrate W2 on the Z-axis negative direction side (vertical direction lower side) of the first substrate W1, and bonds the first substrate W1 and the second substrate W2. . Therefore, hereinafter, the first substrate W1 may be referred to as "upper wafer W1," the second substrate W2 may be referred to as "lower wafer W2," and the bonded substrate T may be referred to as "bonded wafer T." In addition, among the plate surfaces of the upper wafer W1, the plate surface on the side to be bonded to the lower wafer W2 is referred to as a "bonded surface W1j", and the plate surface on the opposite side to the bonded surface W1j is referred to as a "non-bonded surface W1n". That's what it means. Further, among the plate surfaces of the lower wafer W2, the plate surface on the side to be bonded to the upper wafer W1 is referred to as a "bonded surface W2j", and the plate surface on the opposite side to the bonded surface W2j is referred to as a "non-bonded surface W2n".

As shown in FIG. 2, the bonding apparatus 1 includes a processing container 210 whose interior can be sealed. A loading/unloading port 211 is formed on the side surface of the processing container 210, and an opening/closing shutter 212 is provided at the loading/unloading port 211. The upper wafer W1, the lower wafer W2, and the bonded wafer T are carried in and out through the carry-in/out port 211.

As shown in FIG. 3, inside the processing container 210, an upper chuck (first holding section) 230 and a lower chuck (second holding section) 231 are provided. The upper chuck 230 holds the upper wafer W1 from above with the bonding surface W1j of the upper wafer W1 facing downward. Further, the lower chuck 231 is provided below the upper chuck 230, and holds the lower wafer W2 from below with the bonding surface W2j of the lower wafer W2 facing upward.

The upper chuck 230 is supported by a support member 280 provided on the ceiling surface of the processing container 210. On the other hand, the lower chuck 231 is supported by a first lower chuck moving section 291 provided below the lower chuck 231, and can be placed at a position opposite the upper chuck 230.

The first lower chuck moving unit 291 moves the lower chuck 231 in the horizontal direction (Y-axis direction) as described later. Further, the first lower chuck moving unit 291 is configured to be able to move the lower chuck 231 in the vertical direction and rotate around the vertical axis.

The first lower chuck moving section 291 is provided on the lower surface side of the first lower chuck moving section 291 and attached to a pair of rails 295 extending in the horizontal direction (Y-axis direction). The first lower chuck moving section 291 is configured to be movable along the rail 295. The rail 295 is provided on the second lower chuck moving section 296.

The second lower chuck moving section 296 is provided on the lower surface side of the second lower chuck moving section 296 and is attached to a pair of rails 297 extending in the horizontal direction (X-axis direction). The second lower chuck moving section 296 is configured to be movable along the rail 297. A pair of rails 297 are provided on a mounting table 298 provided on the bottom surface of the processing container 210.

A moving mechanism 290 is configured by the first lower chuck moving section 291 and the second lower chuck moving section 296. The moving mechanism 290 moves the lower chuck 231 relative to the upper chuck 230. Furthermore, the moving mechanism 290 moves the lower chuck 231 between the substrate transfer position and the bonding position.

The substrate transfer positions are such that the upper chuck 230 receives the upper wafer W1 from the transfer device 61 (see FIG. 2), the lower chuck 231 receives the lower wafer W2 from the transfer device 61, and the lower chuck 231 transfers the bonded wafer T to the transfer device. This is the position where it is handed over to 61. The substrate delivery position is such that the unloading of the bonded wafer T produced in the n-th bonding (n is a natural number of 1 or more) and the loading of the upper wafer W1 and lower wafer W2 to be bonded in the n+1-th bonding are carried out in succession. This is the position where it is performed. The substrate delivery position is, for example, the position shown in FIGS. 2 and 3.

The transport device 61 enters directly below the upper chuck 230 when transferring the upper wafer W1 to the upper chuck 230. Further, the transfer device 61 enters directly above the lower chuck 231 when receiving the bonded wafer T from the lower chuck 231 and transferring the lower wafer W2 to the lower chuck 231. The upper chuck 230 and the lower chuck 231 are shifted laterally so that the transport device 61 can easily enter, and the vertical distance between the upper chuck 230 and the lower chuck 231 is also large.

On the other hand, the bonding position is a position where the upper wafer W1 and the lower wafer W2 face each other with a predetermined interval. The joining position is, for example, the position shown in FIG. At the bonding position, the distance between the upper wafer W1 and the lower wafer W2 in the vertical direction is narrower than at the substrate transfer position. Further, at the bonding position, unlike the substrate transfer position, the upper wafer W1 and the lower wafer W2 overlap when viewed in the vertical direction.

The moving mechanism 290 moves the relative positions of the upper chuck 230 and the lower chuck 231 in the horizontal direction (both the X-axis direction and the Y-axis direction) and the vertical direction. Although the moving mechanism 290 moves the lower chuck 231 in this embodiment, it may move either the lower chuck 231 or the upper chuck 230, or it may move both. Further, the moving mechanism 290 may rotate the upper chuck 230 or the lower chuck 231 around a vertical axis.

As shown in FIG. 4, the upper chuck 230 is divided into a plurality of (eg, three) regions 230a, 230b, and 230c along the radial direction of the upper chuck 230. These regions 230a, 230b, and 230c are provided in this order from the center of the upper chuck 230 toward the outer edge. The region 230a is formed in a perfect circular shape when viewed from above, and the regions 230b and 230c are formed into an annular shape when viewed from above. The regions 230b and 230c may have a plurality of arcuate zones (small regions) along the circumferential direction.

Suction tubes 240a, 240b, 240c are independently provided in each region 230a, 230b, 230c. Different vacuum pumps 241a, 241b, 241c are connected to each suction pipe 240a, 240b, 240c, respectively. Thereby, the upper chuck 230 can vacuum-hold the upper wafer W1 in each region 230a, 230b, and 230c.

The upper chuck 230 is provided with a plurality of holding pins 245 that are vertically movable. The plurality of holding pins 245 are connected to a vacuum pump 246, and the upper wafer W1 is vacuum-adsorbed by the operation of the vacuum pump 246. The upper wafer W1 is vacuum-adsorbed to the lower ends of the plurality of holding pins 245. A ring-shaped suction pad may be used instead of the plurality of holding pins 245.

The plurality of holding pins 245 protrude from the suction surface of the upper chuck 230 by being lowered by a drive unit (not shown). In this state, the plurality of holding pins 245 vacuum adsorb the upper wafer W1 and receive it from the transfer device 61. Thereafter, the plurality of holding pins 245 rise, and the upper wafer W1 comes into contact with the suction surface of the upper chuck 230. Subsequently, the upper chuck 230 horizontally vacuum-chucks the upper wafer W1 in each region 230a, 230b, 230c by operating the vacuum pumps 241a, 241b, 241c.

Further, the upper chuck 230 includes a through hole 243 in the center thereof that vertically passes through the upper chuck 230. The pushing portion 250 is inserted into the through hole 243 . The pushing unit 250 presses the center of the upper wafer W1, which is spaced apart from the lower wafer W2, thereby bringing the upper wafer W1 into contact with the lower wafer W2.

The pushing part 250 includes a pushing pin 251 and an outer cylinder 252 that is a guide for raising and lowering the pushing pin 251. The push pin 251 is inserted into the through hole 243 by, for example, a drive unit (not shown) having a built-in motor, projects from the suction surface of the upper chuck 230, and presses down the center of the upper wafer W1.

Further, the lower chuck 231 is also divided into a plurality of (for example, three) regions 231a, 231b, and 231c along the radial direction of the lower chuck 231. These regions 231a, 231b, and 231c are provided in this order from the center of the lower chuck 231 toward the outer edge. The region 231a is formed in a perfect circular shape when viewed from above, and the regions 231b and 231c are formed into an annular shape when viewed from above. The regions 230b and 230c may have a plurality of arcuate zones (small regions) along the circumferential direction.

Suction tubes 260a, 260b, 260c are independently provided in each region 231a, 231b, 231c. Different vacuum pumps 261a, 261b, 261c are connected to each suction pipe 260a, 260b, 260c, respectively. Thereby, the lower chuck 231 can vacuum suck the lower wafer W2 in each region 231a, 231b, and 231c.

This lower chuck 231 is provided with a plurality of (for example, three) holding pins 265 that are vertically movable up and down. The lower wafer W2 is placed on the upper ends of the plurality of holding pins 265. Note that the lower wafer W2 may be vacuum-adsorbed to the upper ends of the plurality of holding pins 265.

The plurality of holding pins 265 protrude from the suction surface of the lower chuck 231 by rising. In this state, the plurality of holding pins 265 receive the lower wafer W2 from the transport device 61. Thereafter, the plurality of holding pins 265 descend, so that the lower wafer W2 comes into contact with the suction surface 300 of the lower chuck 231. Subsequently, the lower chuck 231 horizontally vacuum-chucks the lower wafer W2 in multiple regions of the suction surface 300.

Returning to FIG. 2, the bonding apparatus 1 includes a control device (control unit) 90 that controls each component. The control device 90 is a control computer having one or more processors 91, a memory 92, an input/output interface (not shown), and an electronic circuit. One or more processors 91 are a combination of one or more of a CPU, an ASIC, an FPGA, a circuit made of a plurality of discrete semiconductors, etc., and execute programs stored in the memory 92. Memory 92 includes nonvolatile memory and volatile memory, and forms the storage section of control device 90.

Next, with reference to FIGS. 5 to 7, the process of manufacturing the bonded wafer T in the bonding apparatus 1 will be described in detail. As shown in FIG. 5, the control device 90 carries the upper wafer W1 and the lower wafer W2 into the bonding device 1 using the transport device 61 (step S101). The relative positions of the upper chuck 230 and the lower chuck 231 after loading are the substrate transfer positions shown in FIGS. 6 and 7.

After the loading, the control device 90 causes the moving mechanism 290 to move the relative positions of the upper chuck 230 and the lower chuck 231 from the substrate transfer position to the bonding position shown in FIG. 7 (step S102). In this step S112, the control device 90 aligns the upper wafer W1 and the lower wafer W2 using the upper camera S1 and the lower camera S2, as shown in FIG.

The upper camera S1 is fixed to the upper chuck 230 and images the lower wafer W2 held by the lower chuck 231. A plurality of reference points P21 to P23 are formed in advance on the bonding surface W2j of the lower wafer W2. Patterns such as electronic circuits are used as the reference points P21 to P23. The number of reference points can be set arbitrarily.

On the other hand, the lower camera S2 is fixed to the lower chuck 231 and images the upper wafer W1 held by the upper chuck 230. A plurality of reference points P11 to P13 are formed in advance on the bonding surface W1j of the upper wafer W1. Patterns such as electronic circuits are used as the reference points P11 to P13. The number of reference points can be set arbitrarily.

As shown in FIG. 6(A), the bonding device 1 uses the moving mechanism 290 to adjust the relative horizontal position of the upper camera S1 and the lower camera S2. Specifically, the moving mechanism 290 moves the lower chuck 231 in the horizontal direction so that the lower camera S2 is located substantially directly below the upper camera S1. Then, the moving mechanism 290 moves the horizontal position of the lower camera S2 so that the upper camera S1 and the lower camera S2 image a common target X, and the horizontal positions of the upper camera S1 and the lower camera S2 match. Fine-tune.

Next, as shown in FIG. 6(B), the moving mechanism 290 moves the lower chuck 231 vertically upward to adjust the horizontal positions of the upper chuck 230 and the lower chuck 231. Specifically, while the moving mechanism 290 moves the lower chuck 231 in the horizontal direction, the upper camera S1 sequentially images the reference points P21 to P23 of the lower wafer W2, and the lower camera S2 images the reference points P21 to P23 of the upper wafer W1. Images of P11 to P13 are sequentially captured. Note that FIG. 6B shows how the upper camera S1 images the reference point P21 of the lower wafer W2, and the lower camera S2 images the reference point P11 of the upper wafer W1.

The upper camera S1 and the lower camera S2 transmit captured image data to the control device 90. The control device 90 controls the moving mechanism 290 based on the image data captured by the upper camera S1 and the image data captured by the lower camera S2, and moves the reference points P11 to P13 of the upper wafer W1 and the lower one in the vertical direction. The horizontal position of the lower chuck 231 is adjusted so that the reference points P21 to P23 of the wafer W2 coincide with each other.

Next, as shown in FIG. 6(C), the moving mechanism 290 moves the lower chuck 231 vertically upward. As a result, the distance G (see FIG. 7) between the bonding surface W2j of the lower wafer W2 and the bonding surface W1j of the upper wafer W1 becomes a predetermined distance, for example, 80 μm to 200 μm. To adjust the distance G, a first displacement meter S3 and a second displacement meter S4 are used.

Like the upper camera S1, the first displacement meter S3 is fixed to the upper chuck 230, and measures the thickness of the lower wafer W2 held by the lower chuck 231. The first displacement meter S3 measures the thickness of the lower wafer W2 by emitting light onto the lower wafer W2, for example, and receiving reflected light reflected from both the upper and lower surfaces of the lower wafer W2. This thickness measurement is performed, for example, when the moving mechanism 290 moves the lower chuck 231 in the horizontal direction. The measurement method of the first displacement meter S3 is, for example, a confocal method, a spectral interference method, or a triangulation method. The light source of the first displacement meter S3 is an LED or a laser.

On the other hand, the second displacement meter S4 is fixed to the lower chuck 231 like the lower camera S2, and measures the thickness of the upper wafer W1 held by the upper chuck 230. The second displacement meter S4 measures the thickness of the upper wafer W1 by emitting light onto the upper wafer W1, for example, and receiving reflected light reflected from both the upper and lower surfaces of the upper wafer W1. This thickness measurement is performed, for example, when the moving mechanism 290 moves the lower chuck 231 in the horizontal direction. The measurement method of the second displacement meter S4 is, for example, a confocal method, a spectral interference method, or a triangulation method. The light source of the second displacement meter S4 is an LED or a laser.

The first displacement meter S3 and the second displacement meter S4 transmit measured data to the control device 90. The control device 90 controls the moving mechanism 290 based on the data measured by the first displacement meter S3 and the data measured by the second displacement meter S4, and moves the lower chuck 231 in the vertical direction so that the interval G becomes the set value. Adjust the position.

Next, the operation of the vacuum pump 241a is stopped, and as shown in FIG. 7(A), the vacuum suction of the upper wafer W1 in the area 230a is released. Thereafter, the pushing pin 251 of the pushing part 250 descends to push down the center of the upper wafer W1, thereby bringing the upper wafer W1 into contact with the lower wafer W2 (step S103 in FIG. 5). As a result, the centers of the upper wafer W1 and the lower wafer W2 are joined together.

The bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are each modified, and first, van der Waals force (intermolecular force) is generated between the bonding surfaces W1j and W2j, and the bonding surfaces W1j and W2j are are joined together. Furthermore, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are each made hydrophilic, the hydrophilic groups (for example, OH groups) form hydrogen bonds, and the bonding surfaces W1j and W2j are firmly bonded to each other. .

Next, the control device 90 stops the operation of the vacuum pump 241b, and releases the vacuum suction of the upper wafer W1 in the area 230b, as shown in FIG. 7(B). Subsequently, the control device 90 stops the operation of the vacuum pump 241c, and releases the vacuum suction of the upper wafer W1 in the area 230c, as shown in FIG. 7(C).

In this way, the vacuum suction of the upper wafer W1 is released in stages from the center to the periphery of the upper wafer W1, and the upper wafer W1 falls in stages to come into contact with the lower wafer W2. Then, the bonding of the upper wafer W1 and the lower wafer W2 progresses sequentially toward the periphery after bonding at the center (step S104). As a result, the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 come into contact with each other on their entire surface, and the upper wafer W1 and the lower wafer W2 are bonded, and a bonded wafer T is obtained. Thereafter, the control device 90 raises the push pin 251 to its original position.

After forming the bonded wafer T, the control device 90 uses the moving mechanism 290 to move the relative positions of the upper chuck 230 and the lower chuck 231 from the bonding position shown in FIG. 4 to the substrate transfer position shown in FIGS. 2 and 3 ( Step S105). For example, the moving mechanism 290 first lowers the lower chuck 231 to widen the distance between the lower chuck 231 and the upper chuck 230 in the vertical direction. Subsequently, the moving mechanism 290 moves the lower chuck 231 laterally, and shifts the lower chuck 231 and the upper chuck 230 laterally.

After that, the control device 90 transports the bonded wafer T from the bonding device 1 using the transport device 61 (step S106). Specifically, first, the holding of the bonded wafer T by the lower chuck 231 is released. Subsequently, the control device 90 raises the plurality of holding pins 265 and transfers the bonded wafer T to the transfer device 61. Thereafter, the plurality of holding pins 265 are lowered to their original positions.

As shown in FIG. 8, the bonding apparatus 1 described above includes a plurality of displacement sensors 10 (measuring devices) that measure the relative distance to the upper wafer W1 in order to recognize the progress of bonding between the upper wafer W1 and the lower wafer W2. ) inside the upper chuck 230 (holding part). For example, the plurality of displacement sensors 10 include an inner displacement sensor 10a provided in a region 230a of the upper chuck 230, an intermediate displacement sensor 10b provided in a region 230b, and an outer displacement sensor 10c provided in a region 230c. Note that the bonding apparatus 1 may also include a plurality of displacement sensors 10 on the lower chuck 231 to measure the relative distance to the lower wafer W2 (see FIG. 6(A)).

Each displacement sensor 10 (inner displacement sensor 10a, intermediate displacement sensor 10b, and outer displacement sensor 10c) is arranged inside the upper chuck 230 at a position facing the upper wafer W1 held by the upper chuck 230. Each displacement sensor 10 measures the distance from its installation position to the opposing surface (non-bonding surface W1n) of the upper wafer W1. As a result, the displacement sensor 10 can obtain the relative distance between the displacement sensor 10 and the upper wafer W1.

In addition, each displacement sensor 10 according to the present embodiment emits white (multicolor) measurement light to the upper wafer W1, and utilizes information on the color reflected from the surface (non-bonding surface W1n) of the upper wafer W1. A white confocal sensor is used to measure distance. The white confocal displacement sensor 10 includes a white LED (not shown) and a lens module (not shown) that focuses measurement light emitted from the white LED for each color (each of a plurality of wavelengths) at different positions on the optical axis. Has it inside. Further, the white confocal displacement sensor 10 includes a detector (not shown) that separates reflected light and detects a reflection spectrum.

For example, as shown in FIG. 9A, the displacement sensor 10 sets the focal length of the blue light BL to the farthest distance, sets the focal length of the red light RL to the closest distance, and sets the focal length of the green light GL to the furthest distance. Set. Light of a color (wavelength) that is focused on the upper surface of the upper wafer W1 is most strongly reflected. Therefore, the displacement sensor 10 can measure the relative distance between the displacement sensor 10 and the upper wafer W1 from the wavelength of the peak of the reflection spectrum. Note that the order and distances of the focal positions of the red light RL, green light GL, and blue light BL are not particularly limited, and may be arbitrarily set depending on the device to which they are applied. In this way, by applying the white confocal displacement sensor 10, the bonding apparatus 1 does not require contact with the upper wafer W1 during measurement, and it becomes possible to obtain high measurement accuracy.

However, when the white confocal displacement sensor 10 measures the relative distance to the upper wafer W1, there are cases where measurement cannot be performed due to the influence of a film formed on the upper surface of the upper wafer W1 (non-bonding surface W1n). do. This is because, depending on the film type and film thickness of the film on the wafer W, thin film interference occurs in which a specific wavelength out of a plurality of wavelengths is not reflected. In particular, when the silicon nitride film WB is formed as the film on the upper wafer W1, a slight change in film thickness will significantly change the reflectance for each wavelength. Note that the film formed on the upper surface of upper wafer W1 (non-bonding surface W1n) was unintentionally formed when forming a film on the lower surface of upper wafer W1 (bonding surface W1j). It's okay. In this case, the thickness of the film formed on the upper surface of the upper wafer W1 tends to vary. Hereinafter, with reference to FIG. 9, the relationship between the film thickness of the upper wafer W1 and the wavelength that cannot be measured by the displacement sensor 10 will be described.

As shown in FIG. 9A, when the silicon nitride film WB formed on the upper wafer W1 has a thickness of 80 nm, the reflectance in the wavelength region of the red light RL (about 650 nm) is reduced. In this case, if the focus of the red light RL irradiated from the displacement sensor 10 to the upper wafer W1 coincides with the upper surface of the upper wafer W1, the height of the peak of the reflection spectrum (the amount of light received) will decrease significantly, The measurement accuracy of the relative distance between the displacement sensor 10 and the upper wafer W1 decreases.

As shown in FIG. 9B, when the silicon nitride film WB formed on the upper wafer W1 has a thickness of 70 nm, the reflectance in the wavelength region of green light GL (about 550 nm) is reduced. In this case, if the focus of the green light GL irradiated from the displacement sensor 10 to the upper wafer W1 coincides with the upper surface of the upper wafer W1, the height of the peak of the reflection spectrum (the amount of received light) will decrease significantly, The measurement accuracy of the relative distance between the displacement sensor 10 and the upper wafer W1 decreases.

As shown in FIG. 9C, when the silicon nitride film WB formed on the upper wafer W1 has a thickness of 60 nm, the reflectance in the wavelength region of blue light BL (about 500 nm) is reduced. In this case, if the focus of the blue light BL irradiated from the displacement sensor 10 to the upper wafer W1 coincides with the upper surface of the upper wafer W1, the height of the peak of the reflection spectrum (the amount of received light) will decrease significantly, The measurement accuracy of the relative distance between the displacement sensor 10 and the upper wafer W1 decreases.

From the above, the bonding apparatus 1 according to the present embodiment accurately measures the relative distance by displacing the relative position (relative distance) between the displacement sensor 10 and the upper wafer W1 according to the amount of light received by the displacement sensor 10. This makes it possible to monitor the position of the upper wafer W1 with high accuracy. The position of the upper wafer W1 is, for example, the position of the upper wafer W1 with respect to the suction surface of the upper chuck 230.

As shown in FIG. 10(A), the bonding apparatus 1 includes a moving unit 11 that moves the relative position in the Z-axis direction (position along the optical axis) of the upper wafer W1 to be measured and the displacement sensor 10. Be prepared. In this embodiment, the moving unit 11 uses a sensor moving unit 11A that moves the displacement sensor 10 while fixing the upper wafer W1 that is attracted to the upper chuck 230.

For example, the sensor moving unit 11A includes a movable body that holds the displacement sensor 10, a rail that guides the movable body in the Z-axis direction, a drive actuator that generates a driving force, and a drive transmission that transmits the driving force of the drive actuator to the movable body. (both not shown). Further, the sensor moving unit 11A is connected to the control device 90, and the drive actuator is driven under the control of the control device 90 to move the displacement sensor 10 relative to the upper chuck 230. When the displacement sensor 10 moves, the control device 90 acquires the amount of movement (movement distance) of the displacement sensor 10 through feedback control, feedforward control, etc., and stores it in the memory 92. Thereby, the distance traveled by the displacement sensor 10 with respect to the reference position of the displacement sensor 10, that is, the position of the displacement sensor 10 can be continuously recognized.

Note that the moving unit 11 is not limited to a configuration in which the displacement sensor 10 is moved, but may be configured to move a holding unit (upper chuck 230) that holds the measurement target (upper wafer W1) relative to the displacement sensor 10. . For example, as shown in FIG. 10(B), the bonding apparatus 1 includes a chuck moving section 11B that moves the upper chuck 230, and the chuck moving section 11B moves the upper chuck 230 in the Z-axis direction. In this case, the displacement sensor 10 only needs to be immovably fixed by a fixed body (not shown) within the joining device 1. Note that in the case of the displacement sensor 10 that measures the position of the lower wafer W2, the moving mechanism 290 may be applied to the moving unit 11. Further, the moving unit 11 may be configured to move both the displacement sensor 10 and the upper wafer W1 and the lower wafer W2 that are the measurement targets.

In measuring the relative distance between each displacement sensor 10 and the upper wafer W1, when each displacement sensor 10 receives reflected light, the control device 90 provides information on the amount of light received at the peak of the reflection spectrum (for example, the current of a photodiode). value). For example, the control device 90 compares the amount of received light with a preset threshold, and if the amount of received light is less than the threshold, the control device 90 causes the moving unit 11 to perform a process of displacing the relative position between the displacement sensor 10 and the measurement target. conduct. The threshold value may be set to an appropriate value depending on the emission intensity of the measurement light of the displacement sensor 10 and the specifications of the sensor itself.

As an example, the control device 90 monitors the amount of light received at the peak of the reflection spectrum while moving the displacement sensor 10 in the Z-axis direction using the sensor moving unit 11A. The peak amount of light received and the peak wavelength gradually change. Then, when the amount of light received by the displacement sensor 10 exceeds a threshold value, the relative distance between the displacement sensor 10 and the upper wafer W1 is measured at that position. The control device 90 calculates the position of the upper wafer W1 with respect to the suction surface of the upper chuck 230 from the relative distance between the displacement sensor 10 and the upper wafer W1 and the moving distance of the sensor moving unit 11A. Thereby, the bonding apparatus 1 can stably detect the position of the upper wafer W1 using the displacement sensor 10.

The bonding device 1 according to this embodiment is basically configured as described above, and its operation (position measuring method) will be described in detail below with reference to FIG. 11.

The control device 90 of the bonding apparatus 1 performs a position measuring method in which the position of the upper wafer W1 is measured by each displacement sensor 10 in steps S103 and S104 of the substrate processing method shown in FIG. As shown in FIG. 11, in the position measurement method, the control device 90 acquires information on the amount of light received at the peak of the reflection spectrum detected by each displacement sensor 10, and compares the amount of received light with a threshold held in advance (step S11). Hereinafter, the first comparison will also be referred to as initial comparison.

As shown in FIG. 12A, when the amount of received light is less than the threshold (step S11: NO), the film type and thickness of the upper wafer W1 are determined at the current relative position between the displacement sensor 10 and the upper wafer W1. Therefore, the reflectance of a predetermined wavelength is weakened. In this case, the measurement accuracy of the relative distance of the upper wafer W1 by the displacement sensor 10 decreases. Therefore, the control device 90 determines whether the relative positions of the displacement sensor 10 and the upper wafer W1 should be displaced, and the process proceeds to step S12.

Conversely, when the amount of received light is equal to or greater than the threshold value, the displacement sensor 10 can accurately measure the relative distance of the upper wafer W1 at the current relative position of the displacement sensor 10 and the upper wafer W1. Therefore, if the amount of received light is equal to or greater than the threshold (step S11: YES), steps S12 and S13 are skipped and the process proceeds to step S14.

In step S12, the control device 90 causes the sensor moving unit 11A to move the displacement sensor 10 in the Z-axis direction. The displacement sensor 10 detects reflected light whose received amount increases as the relative position between the displacement sensor 10 and the upper wafer W1 changes, as shown in FIG. 12(B). Furthermore, when the sensor moving unit 11A moves, the control device 90 also acquires the moving distance of the displacement sensor 10 with respect to the reference position, as described above.

While displacing the displacement sensor 10 and the upper wafer W1, the control device 90 obtains the amount of reflected light received by the displacement sensor 10, and compares the amount of received light with a threshold value (step S13). Hereinafter, the comparison performed when the relative position changes is also referred to as the comparison during movement. The threshold value for initial comparison and the threshold value for comparison during movement may be the same or different. For example, in order to reliably capture the reflected light from the displacement sensor 10 in the moving comparison, the threshold for the moving comparison may be set higher than the threshold for the initial comparison. In the moving comparison, if the amount of received reflected light is less than the threshold (step S13: NO), the process returns to step S12 and the same process is repeated.

On the other hand, as shown in FIG. 12C, if the amount of reflected light received is equal to or greater than the threshold value in the moving comparison (step S13: YES), the displacement sensor 10 accurately measures the relative distance of the upper wafer W1. Be able to measure. Therefore, the control device 90 stops the movement of the displacement sensor 10 by the sensor moving unit 11A, and proceeds to step S14. At this time, the control device 90 calculates the moving distance after the movement (the difference between the reference position and the movement stop position of the displacement sensor 10).

In step S14, the control device 90 measures the relative distance of the upper wafer W1 using the displacement sensor 10. At this time, the control device 90 can smoothly derive the relative distance corresponding to the wavelength (color) based on the measurement information of the displacement sensor 10 (the peak wavelength at which the amount of received reflected light is equal to or higher than the threshold value). can.

Finally, the control device 90 calculates the position of the upper wafer W1 (for example, the relative position of the upper wafer W1 with respect to the suction surface of the upper chuck 230) (step S15). When the relative positions of the displacement sensor 10 and the upper wafer W1 are displaced via steps S12 and S13, the moving distance is added to the relative distance measured by the displacement sensor 10. As an example, when the displacement sensor 10 is moved in a direction away from the upper wafer W1, the control device 90 adds the relative distance and the negative movement distance. On the other hand, when the displacement sensor 10 is moved in a direction approaching the upper wafer W1, the control device 90 adds the relative distance and the positive movement distance. Note that when calculating the relative distance of the upper wafer W1 directly from step S11 (without going through steps S12 and S13), the control device 90 directly applies the relative distance measured by the displacement sensor 10 to the position of the upper wafer W1. Can be converted.

As described above, the substrate processing apparatus (bonding apparatus 1) according to the present embodiment determines the relative relationship between the measuring instrument and the substrate (upper wafer W1) depending on the amount of light received by the white confocal measuring instrument (displacement sensor 10). The position can be adjusted appropriately. As a result, even if the amount of light received by the white confocal measuring device is affected by the film formed on the substrate, the relative distance between the measuring device and the substrate can be stably measured without reducing measurement accuracy. . As a result, the substrate processing apparatus can accurately recognize the position of the substrate, and can monitor the substrate processing and perform the substrate processing itself with higher precision. Note that, if the amount of light received by the measuring device is sufficiently high and equal to or higher than the threshold value, the substrate processing apparatus can immediately recognize the position of the substrate by using the relative distance measured by the measuring device.

In addition, the substrate processing apparatus (bonding apparatus 1) monitors the amount of reflected light received when the moving unit 11 shifts the relative position between the measuring device (displacement sensor 10) and the substrate (upper wafer W1). It becomes possible to reliably measure the relative distance at a relative position where a suitable amount of received light can be obtained. The bonding apparatus 1 to which such a displacement sensor 10 and control device 90 are applied can monitor the bonding of the upper wafer W1 and the lower wafer W2 with higher accuracy.

Note that the bonding apparatus 1 is not limited to the above-mentioned process for the position measuring method using the displacement sensor 10, and may take various modifications.

For example, in the position measuring method shown in the first modification shown in FIG. 13, when the amount of light received by the displacement sensor 10 is less than the threshold value in the initial comparison, the relative position between the displacement sensor 10 and the upper wafer W1 is determined by the sensor moving unit 11A. This method differs from the above position measurement method in that it moves by the distance of movement.

Specifically, in the position measurement method according to the first modification, the control device 90 acquires information on the amount of reflected light detected by each displacement sensor 10, and compares this amount of received light with a threshold value as an initial comparison. (Step S21). If the amount of received light is less than the threshold (step S21: NO), the process proceeds to step S22, while if the amount of received light is greater than or equal to the threshold (step S21: YES), step S22 is skipped and the process proceeds to step S23.

In step S22, the control device 90 causes the sensor moving unit 11A to move the displacement sensor 10 by a specified moving distance in the Z-axis direction. This specified moving distance is preferably set to a value that reliably changes the color (wavelength) of the reflected light set to the focal length. For example, the specified moving distance may be a distance at which the wavelength of the reflected light set as the focal length changes within a range of 50 nm to 200 nm. Thereby, the control device 90 can smoothly perform measurement by the displacement sensor 10 after the displacement of the specified moving distance. Further, by not monitoring the amount of light received by the displacement sensor 10 during movement of the sensor moving unit 11A, the control device 90 can move the displacement sensor 10 to the specified movement distance in a short time. Then, the displacement sensor 10 that has been moved by the predetermined moving distance and stopped by the sensor moving unit 11A can stably detect the amount of received reflected light that is equal to or greater than the threshold value in subsequent measurements.

In step S23, the control device 90 measures the relative distance to the upper wafer W1 using the displacement sensor 10. At this time, the control device 90 can smoothly derive the relative distance corresponding to the wavelength (color) based on the measurement information of the displacement sensor 10 (the peak wavelength at which the amount of received reflected light is equal to or higher than the threshold value). can.

Then, the control device 90 calculates the position of the upper wafer W1 in the Z-axis direction (for example, the relative position of the upper wafer W1 with respect to the suction surface of the upper chuck 230) (step S24). If the displacement sensor 10 is moved relative to the upper wafer W1 via step S22, the specified moving distance may be added to the relative distance of the displacement sensor 10. Therefore, the control device 90 can quickly calculate the position of the upper wafer W1. Note that when directly calculating the position of the upper wafer W1 from step S21, the control device 90 can directly convert the relative distance of the displacement sensor 10 into the position of the upper wafer W1.

In this manner, the substrate processing apparatus (bonding apparatus 1) can stably detect the position of the upper wafer W1 using the displacement sensor 10 even if the relative position is displaced by a prescribed movement distance in the position measuring method. Furthermore, when the amount of light received by the displacement sensor 10 is small, the relative position of the displacement sensor 10 and the board is simply moved by a specified moving distance, so the load of monitoring the amount of light received by the displacement sensor 10 can be reduced. . As a result, the above-described substrate processing apparatus can suppress delays caused by monitoring the position of the upper wafer W1 and improve the efficiency of the substrate processing as a whole.

Further, in the position measuring method shown in the second modification shown in FIG. 14, the state of the film of the upper wafer W1 (film type, film thickness) is recognized, and the displacement sensor 10 is adjusted according to the state of the film of the upper wafer W1. This method differs from the above position measuring method in that the relative position of the upper wafer W1 is displaced.

In this case, the control device 90 of the bonding apparatus 1 generates a map that associates the information on the film type and film thickness of the film formed on the upper wafer W1 with the target position of the relative distance between the displacement sensor 10 and the upper wafer W1. Information is stored in memory 92. Furthermore, before starting substrate processing, the control device 90 acquires information on the film type and film thickness of the film on the upper wafer W1 from a film thickness measuring device (not shown) or input from a user, and stores the information in the memory 92.

In the position measuring method according to the second modification, the control device 90 reads information on the film type and film thickness from the memory 92 before starting substrate processing, and determines the position of the displacement sensor 10 from the map information based on this information. A target position of relative distance is extracted (step S31). Further, the control device 90 causes the sensor moving unit 11A to displace the relative position of the displacement sensor 10 and the upper wafer W1 from the reference position in advance before the measurement by the displacement sensor 10, based on the target position extracted from the map information (step S32). Thereby, the bonding apparatus 1 can arrange the displacement sensor 10 at an appropriate position before the displacement sensor 10 performs measurement.

Thereafter, the control device 90 acquires the amount of reflected light received by the displacement sensor 10, and compares the amount of received light with a threshold value (step S33: initial comparison). If the amount of received reflected light is less than the threshold (step S33: NO), this means that the amount of received light does not exceed the threshold even if the displacement sensor 10 is moved according to the film type and thickness. In this case, this processing flow cannot fully handle the situation, so the process moves to, for example, the processing flow of the position measuring method shown in FIG. 11 (step S12). Thereby, the control device 90 can monitor the amount of received light while moving the displacement sensor 10. On the other hand, if the amount of received reflected light is equal to or greater than the threshold (step S33: YES), the displacement sensor 10 can accurately measure the relative distance of the upper wafer W1. Therefore, the control device 90 proceeds to step S34.

In step S34, the control device 90 measures the relative distance of the upper wafer W1 using the displacement sensor 10. At this time, the control device 90 can smoothly derive the relative distance corresponding to the wavelength (color) based on the measurement information of the displacement sensor 10 (the peak wavelength at which the amount of received reflected light is equal to or higher than the threshold value). can.

Then, the control device 90 calculates the position of the upper wafer W1 in the Z-axis direction (step S35). The control device 90 only needs to add the extracted movement distance of the target position to the relative distance measured by the displacement sensor 10. Therefore, the control device 90 can quickly calculate the position of the upper wafer W1.

As described above, when the film type and film thickness of the film are known in advance, the substrate processing apparatus (bonding apparatus 1) displaces the relative position according to the film type and film thickness. 10) can be more smoothly adjusted to a measurable target position. Moreover, when the amount of light received by the displacement sensor 10 is small, the position of the upper wafer W1 can be stably measured by the displacement sensor 10 by switching to monitoring the amount of light received as the relative position moves.

Furthermore, the substrate processing apparatus that performs the above position measuring method using the displacement sensor 10 is not limited to the bonding apparatus 1, but can be applied to various apparatuses.

For example, the substrate processing apparatus according to the second embodiment shown in FIG. 15(A) is a peeling device 2 that peels off a support wafer WS, which is temporarily bonded to the wafer W via the adhesive layer WG, from the wafer W. A white confocal displacement sensor 10 and a position measuring method are applied to this peeling device 2. The peeling device 2 calculates the position of the upper surface of the support wafer WS by measuring the relative distance between the displacement sensor 10 and the support wafer WS. The peeling device 2 adjusts the height of the blade 20 based on the position of the upper surface of the support wafer WS and the thickness of the support wafer WS. Thereafter, the peeling device 2 performs substrate processing to peel the support wafer WS from the wafer W by inserting the blade 20 into the interface between the support wafer WS and the adhesive layer WG.

Before substrate processing is performed by the peeling device 2, the lower surface side of the wafer W is fixed to a holding section (not shown) via a tape member 81. On the other hand, a support wafer WS is stacked on the upper surface (front surface) of the wafer W via an adhesive layer WG. Devices may be formed on the upper surface of the wafer W. The device includes electronic circuitry. An adhesive layer WG is provided on top of the device. The support wafer WS is a bare wafer, and no devices are formed on the lower surface of the support wafer WS.

Then, in a position measurement method in which the position of the support wafer WS is measured by the displacement sensor 10, the peeling device 2 displaces the relative position of the displacement sensor 10 and the support wafer WS to increase the amount of received reflected light. Thereby, the peeling device 2 can accurately measure the position using the displacement sensor 10, and can accurately adjust the height of the blade 20 to the adhesive layer WG.

Further, the substrate processing apparatus according to the third embodiment shown in FIG. 15(B) is a thickness measuring apparatus 3 in which displacement sensors 10 are respectively installed at positions facing a pair of planes (surfaces) of a wafer W. The thickness measuring device 3 calculates the thickness of the wafer W based on the position of the wafer W, which is the measurement result measured by the pair of displacement sensors 10. In this thickness measuring device 3 as well, by performing the above-described position measuring method when measuring the position of the wafer W by each displacement sensor 10, the position of the wafer W can be obtained with high precision, and the thickness of the wafer W can be accurately measured. It becomes possible to recognize it.

The substrate processing apparatus and position measuring method according to the embodiment disclosed herein are illustrative in all respects and are not restrictive. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the plurality of embodiments described above may be configured in other ways without being inconsistent, and may be combined without being inconsistent.

1 Bonding equipment (substrate processing equipment)
10 Displacement sensor (measuring device)
11 Moving unit 90 Control device (control unit)
230 Upper chuck upper wafer W1

Claims (11)

a holding part that holds the board;
a measuring device that is provided at a position facing the substrate held by the holding section and measures a relative distance with the substrate;
a moving unit that displaces the relative position of the measuring device and the substrate;
a control unit to which the measuring device is connected and which controls the moving unit;
The measuring device detects the reflected light reflected from the surface of the substrate using a white confocal method set to different focal lengths for each of a plurality of wavelengths,
The control section compares the received amount of the reflected light with a threshold value held in advance, and when the received amount of the reflected light is less than the threshold value, causes the moving section to displace the relative position, and then performs the measurement. calculating the position of the substrate using the relative distance measured by the device;
Substrate processing equipment. The control unit calculates the position of the substrate using the relative distance measured by the measuring device without operating the moving unit if the amount of the reflected light received is equal to or greater than the threshold value in the comparison.
The substrate processing apparatus according to claim 1. The control unit includes:
In the comparison, if the received amount of the reflected light is less than the threshold value, monitor the received amount of the reflected light while displacing the relative position by the moving unit,
When the amount of received reflected light exceeds the threshold value, the movement is stopped, and the position of the substrate is calculated using the distance required for movement and the relative distance measured by the measuring device after movement. ,
The substrate processing apparatus according to claim 1. When the received amount of the reflected light is less than the threshold value in the comparison, the control unit causes the moving unit to move the relative position by a predetermined moving distance, and the measuring device measures the predetermined moving distance and the measuring device after the movement. calculating the position of the substrate using the relative distance obtained;
The substrate processing apparatus according to claim 1. The specified moving distance is a distance at which the wavelength of the reflected light set at the focal length changes within a range of 50 nm to 200 nm.
The substrate processing apparatus according to claim 4. a holding part that holds the board;
a measuring device that is provided at a position facing the substrate held by the holding section and measures a relative distance with the substrate;
a moving unit that displaces the relative position of the measuring device and the substrate;
a control unit to which the measuring device is connected and which controls the moving unit;
The measuring device detects the reflected light reflected from the surface of the substrate using a white confocal method set to different focal lengths for each of a plurality of wavelengths,
The control unit has map information that associates the film type and film thickness of the film formed on the substrate with the target position of the relative distance,
The target position is extracted from the map information using the information on the film type and the film thickness, the relative position is displaced by the moving unit according to the extracted target position, and then the relative position measured by the measuring device is calculating the position of the substrate using the distance;
Substrate processing equipment. The holding part is
a first holding part that holds the first substrate, which is the substrate;
a second holding part that can be disposed at a position opposite to the first holding part and has a suction surface divided into a plurality of areas for suctioning a second substrate;
a pressing portion that presses a center portion of the first substrate toward the second substrate in order to bond the first substrate to the second substrate;
The control unit calculates the position of the first substrate using the relative distance between the measuring device and the first substrate measured by the measuring device when the first substrate is pressed by the pushing unit.
A substrate processing apparatus according to any one of claims 1 to 6. The measuring devices are provided at positions facing each other on both sides of the substrate,
The control unit calculates the thickness of the substrate based on the measurement result of the measuring device.
A substrate processing apparatus according to any one of claims 1 to 6. The film formed on the substrate is a silicon nitride film,
A substrate processing apparatus according to any one of claims 1 to 6. A position measuring method for measuring the position of the substrate by measuring a relative distance between the measuring device and the substrate using a measuring device provided at a position opposite to the substrate held in a holding part,
Detecting the reflected light reflected from the surface of the substrate using the white confocal measuring device set to different focal lengths for each of a plurality of wavelengths;
a step of comparing a previously held threshold value and the amount of received reflected light;
When the amount of received reflected light is less than the threshold value in the comparison, displacing the relative position by a moving unit;
after displacing the relative position, calculating the position of the substrate using the relative distance measured by the measuring device;
Location measurement method. A position measuring method for measuring the position of the substrate by measuring a relative distance between the measuring device and the substrate using a measuring device provided at a position opposite to the substrate held in a holding part,
Detecting the reflected light reflected from the surface of the substrate using the white confocal measuring device set to different focal lengths for each of a plurality of wavelengths;
From map information that associates the film type and film thickness of the film formed on the substrate with the target position of the relative position of the measuring device and the substrate, the film type and film thickness information is used to determine the a step of extracting a target position;
Displacing the relative position by a moving unit according to the extracted target position;
after displacing the relative position, calculating the position of the substrate using the relative distance measured by the measuring device;
Location measurement method.

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