Patent ID: 12198955

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments.

<Substrate Processing System>

First, a substrate processing system including a substrate transfer system according to an embodiment will be described.FIG.1is a schematic plan view illustrating an example of an overall configuration of the substrate processing system.

A substrate processing system1illustrated inFIG.1processes a substrate W in a vacuum atmosphere, and is configured as a cluster structure (multi-chamber type) system. An example of the substrate W includes, but is not limited to, a wafer such as a semiconductor wafer.

The substrate processing system1includes a load-lock chamber2, a vacuum transfer chamber3, a processing chamber4, a substrate transfer mechanism5, a sensor unit6, and a controller7. A substrate transfer system according to an embodiment includes the substrate transfer mechanism5, the sensor unit6, and the controller7.

The vacuum transfer chamber3has a rectangular planar shape. The interior of the vacuum transfer chamber is depressurized to a vacuum atmosphere by a vacuum exhaust part (not illustrated). The substrate transfer mechanism5is provided inside the vacuum transfer chamber3. Three load-lock chambers2are connected to the wall corresponding to one long side of the vacuum transfer chamber3. In addition, a total of four processing chambers4are connected to opposite walls corresponding to the two short sides, two processing chambers for each wall.

The load-lock chambers2are provided between the vacuum transfer chamber3and an atmospheric transfer chamber (not illustrated) and each provided therein with a stage21on which the substrate W is placed. A gate valve22is provided between each load-lock chamber2and the vacuum transfer chamber3, and a gate valve (not illustrated) is also provided between each load-lock chamber2and the atmospheric transfer chamber. The load-lock chamber2and the vacuum transfer chamber3in a vacuum atmosphere communicate with each other/are shut off by opening/closing the gate valve22. The load-lock chamber2and the atmosphere transfer chamber also communicate with each other/are shut off by opening/closing the gate valve (not illustrated). An internal pressure of each load-lock chamber2may be controlled between atmospheric pressure and vacuum atmosphere, in a state in which both gate valves are closed. When the substrate W is delivered to the atmospheric transfer chamber, the interior of the load-lock chamber2is made into an air atmosphere, and the gate valve on the side of the atmospheric transfer chamber is opened. When the substrate W is delivered to the vacuum transfer chamber3, the interior of the load-lock chamber2is made into a vacuum atmosphere, and the gate valve22is opened.

As described above, the processing chambers4are connected to the walls corresponding to the short sides of the vacuum transfer chamber3and each provided therein with a stage41on which the substrate W is placed. Each processing chamber4is depressurized to a vacuum atmosphere. Inside the processing chamber4, a desired process (e.g., an etching process, a film forming process, a cleaning process, an ashing process, or the like) is performed on the substrate W placed on the stage41. Between each processing chamber4and the vacuum transfer chamber3, a gate valve42is provided. The processing chamber4and the vacuum transfer chamber3communicate with the gate valve42and are shut off by opening/closing the gate valve42.

The substrate transfer mechanism5transfers substrates between the stages21of the load-lock chambers2and the stages41of the processing chambers4. The substrate transfer mechanism5is configured as an articulated arm including, for example, a base50, a first arm51, a second arm52, a third arm53, and a fourth arm54. The base50and one side of the first arm51in the longitudinal direction are rotatably connected to each other by a rotation axis55. The other side of the first arm51in the longitudinal direction and one side of the second arm52in the longitudinal direction are rotatably connected to each other by a rotation axis56. The other side of the second arm52in the longitudinal direction and the one side of the third arm53in the longitudinal direction are rotatably connected to each other by a rotation axis57. The other side of the third arm53in the longitudinal direction includes a holder53athat holds (places) the substrate W thereon. In addition, the other side of the second arm52in the longitudinal direction and one side of the fourth arm54in the longitudinal direction are rotatably connected to each other by a rotation axis57. The other side of the fourth arm54in the longitudinal direction includes a holder54athat holds (places) the substrate W thereon. The details of the substrate transfer mechanism5will be described later.

Inside the vacuum transfer chamber3, sensor units (measurement parts)6that detect the substrate W transferred by the substrate transfer mechanism5are provided to correspond to the four processing chambers4and the three load-lock chambers2, respectively. Each of the sensor units6is provided at a position through which the substrate W passes when the substrate transfer mechanism5transfers the substrate W from a corresponding one of the processing chambers4or the load-lock chambers2to the vacuum transfer chamber3, or when the substrate transfer mechanism5transfers the substrate W from the vacuum transfer chamber3to a corresponding one of the processing chambers4or the load-lock chambers2.

Each of the sensor units6includes two sensors6aand6b. The sensors6aand6bare, for example, photoelectric sensors. When the substrate W transferred by the substrate transfer mechanism5passes through the sensors6aand6b, four points on the outer edge of the substrate W may be detected by the sensors6aand6b.

The controller7controls the operation of each component of the substrate processing system1, such as the substrate transfer mechanism5, an exhaust system of the load-lock chambers2, the vacuum transfer chamber3and the processing chambers4, the gate valves22and42, and the like. The controller7is typically a computer, and includes a main controller, an input device, an output device, a display device, and a storage device. The main controller includes a central processing unit (CPU), RAM, and ROM. The storage device includes a computer-readable storage medium such as a hard disk, and is configured to record and read information necessary for control. In the controller7, the CPU uses the RAM as a work region to execute a program such as a processing recipe stored in the storage medium of the ROM or the storage device, thereby controlling processing of the substrate W or transfer of the substrate W in the substrate processing system1.

As will be described later, the controller7receives information on the thermal expansion of the substrate transfer mechanism5and corrects the positions of the holder53aand the holder54aof the substrate transfer mechanism5.

The controller7detects edge coordinates of the substrate W held by the holder53aof the third arm53based on the detection of the outer edge of the substrate W by a sensor unit6(sensors6aand6b) and the operation of the substrate transfer mechanism5at that time. Then, the controller7calculates the center position of the substrate W from the detected outer edge coordinates of the four points. Therefore, the sensor unit6and the controller7function as a measurement part that measures the center position of the substrate W held by the third arm53. The controller7detects a deviation (eccentric amount) between a reference position (the center position of the holder53a) on which the substrate W is placed in the third arm53, wherein the reference position is set in advance, and the center position of the substrate W held on the holder53aof the third arm53, wherein the center position of the substrate is detected by the sensor unit6. The controller7also controls the holder54aof the fourth arm54in the same manner.

<Substrate Transfer Mechanism>

Next, the substrate transfer mechanism5will be described in more detail with reference toFIGS.2and3.FIG.2is a perspective view illustrating an example of the substrate transfer mechanism5, andFIG.3is a schematic view illustrating the structure of an example of the substrate transfer mechanism5.

In the substrate transfer mechanism5, a first axis motor91, a gear92rotated by the first axis motor91, and a gear93that is engaged with the gear92are provided on the lower side in the first arm51. The gear93is fixed to the base50and is arranged coaxially with the rotation axis55. The gears92and93configures a power transmission mechanism. By rotating the gear92by the first axis motor91, the first arm51is rotated around the rotation axis55with respect to the base50.

Further, on the upper side in the first arm51, a second axis motor94, a gear95rotated by the second axis motor94, and a gear96that is engaged with the gear95are provided. The gear96is fixed to the second arm52and is arranged coaxially with the rotation axis56. The gears95and96constitute a power transmission mechanism. By rotating the gear95by the second axis motor94, the second arm52is rotated around the rotation axis56with respect to the first arm51.

In the second arm52, a third axis motor97, a gear98rotated by the third axis motor97, and a gear99that is engaged with the gear98are provided. A gear99is fixed to the third arm53and is arranged coaxially with the rotation axis57. The gears98and99constitute a power transmission mechanism. By rotating the gear98by the third axis motor97, the third arm53is rotated around the rotation axis57with respect to the second arm52. Similarly, inside the second arm52, a motor (not illustrated) that rotates the fourth arm54and a power transmission mechanism (not illustrated) constituted with a pair of gears are provided. The fourth arm54is rotated about the rotation axis57with respect to the second arm52by the motor via the power transmission mechanism.

The first arm51is provided with temperature sensors (temperature detectors)81and82. As the temperature sensors81and82, for example, thermocouples may be used. The temperature sensor81is provided on one side of the first arm51in the longitudinal direction (the side of the rotation axis55), and the temperature sensor82is provided on the other side of the first arm51in the longitudinal direction (the side of the rotation axis56). Information about the temperature of the first arm51detected by the temperature sensors81and82is input to the controller7.

The second arm52is provided with temperature sensors (temperature detectors)83and84. As the temperature sensors83and84, for example, thermocouples may be used. The temperature sensor83is provided on one side of the second arm52in the longitudinal direction (the side of the rotation axis56), and the temperature sensor84is provided on the other side of the second arm52in the longitudinal direction (the side of the rotation axis57). The temperature of the second arm52detected by the temperature sensors83and84is input to the controller7.

Next, the thermal expansion in the substrate transfer mechanism5will be described.

In the substrate transfer mechanism5, the first axis motor91or the like provided therein serves as a heat source and generates heat. In addition, when the processing chamber4has a high temperature, heat is input from the processing chamber4to the substrate transfer mechanism5. Furthermore, heat is input to the substrate transfer mechanism5from a hot substrate W processed in the processing chamber4. As a result, thermal expansion occurs in the substrate transfer mechanism5.

In the following description, it is assumed that an inter-axis distance between the rotation axis55and the rotation axis56(a link length of the first arm51) is L1 and an inter-axis distance between the rotation axis56and the rotation axis57(a link length of the second arm52) is L2. In addition, it is assumed that an inter-axis distance between the gear92and the gear93is Lg1, an inter-axis distance between the gear95and the gear96is Lg2, and an inter-axis distance between the gear98and the gear99is Lg3 (seeFIG.3). The material of each of the gears92,95and98is, for example, Fe, and the material of each of the first arm51, the second arm52, the third arm53, the fourth arm54, and the gears93,96and99is, for example, Al.

As indicated by the black arrows inFIG.2, when heat is input to the substrate transfer mechanism5, the first arm51, the second arm52, the third arm53, and the fourth arm54thermally expand in the longitudinal direction.

In addition, backlash of the gears92and93increases due to the thermal expansion of the gears92and93. InFIG.2, the position of the central axis of the first arm51in the longitudinal direction is indicated by the alternate long and short dash line, and the position of the central axis of the first arm51in the longitudinal direction, which is subjected to backlash, is indicated by the alternate long and two short dashes line. As indicated by the white arrows inFIG.2, when the first arm51is rotated on the rotation axis55by the gears92and93, an angle transmission error occurs. Similarly, in the gears95and96and the gears98and99as well, backlash increases and an angle transmission error occurs.

FIG.4is a functional block diagram when the substrate transfer mechanism5is controlled by the controller7. The controller7performs the control of the substrate transfer mechanism5, including the correction of thermal expansion.

The substrate transfer mechanism5includes a first axis angle sensor91a, a second axis angle sensor94a, and a third axis angle sensor97athat detect a rotation angle of the first axis motor91, a rotation angle of the second axis motor94, and a rotation angle of the third axis motor97, respectively. Then, values detected by the first axis angle sensor91a, the second axis angle sensor94a, and the third axis angle sensor97aare input to the controller7. The controller7controls the operation of the substrate transfer mechanism5by controlling the first axis motor91, the second axis motor94, and the third axis motor97based on the values detected by the first axis angle sensor91a, the second axis angle sensor94a, and the third axis angle sensor97a.

In addition, the values detected by the temperature sensors81to84and the values detected by the sensor unit6are also input to the controller7.

The controller7includes a thermal expansion amount estimation part71, an angle transmission error estimation part72, an angle error direction estimation part73, and a transfer position correction part74.

The thermal expansion amount estimation part71estimates the thermal expansion amounts of the first arm51and the second arm52.

When estimating the thermal expansion amount of the first arm51, the thermal expansion amount estimation part71estimates the thermal expansion amount based on, for example, the temperature of the first arm51, the thermal expansion coefficient of the first arm51, and the reference link length L1 of the first arm51. The temperature of the first arm51is detected by the temperature sensors81and82. For example, the average value of the temperature sensors81and82may be the temperature of the first arm51. When the first arm51is made of Al, the thermal expansion coefficient of the first arm51may be the thermal expansion coefficient of Al. The reference link length L1 of the first arm51is the link length of the first arm51at a reference temperature.

When estimating the thermal expansion amount of the second arm52, the thermal expansion amount estimation part71estimates the thermal expansion amount based on, for example, the temperature of the second arm52, the thermal expansion coefficient of the second arm52, and the reference link length L2 of the second arm52. The temperature of the second arm52is detected by the temperature sensors83and84. For example, the average value of the temperature sensors83and84may be the temperature of the second arm52. When the second arm52is made of Al, the thermal expansion coefficient of the second arm52may be the thermal expansion coefficient of Al. The reference link length L2 of the second arm52is the link length of the second arm52at the reference temperature.

The angle transmission error estimation part72estimates an amount of angle transmission error due to gear backlash.

When estimating the amount of angle transmission error when the first arm51is rotated by the rotation axis55, the angle transmission error estimation part72estimates the amount of angle transmission error based on, for example, the temperatures of the gears92and93, a difference between the thermal expansion coefficients of the gears92and93, and the distance Lg1 between the reference axes of the gears92and93. The temperatures of the gears92and93are detected by, for example, the temperature sensor81. When the gear92is made of Fe and the gear93is made of Al, the difference in the thermal expansion coefficients between the gears92and93may be a difference between the thermal expansion coefficient of Al and the thermal expansion coefficient of Fe. The distance Lg1 between the reference axes is an inter-axis distance of the gears92and93at the reference temperature.

When estimating the amount of angle transmission error when the second arm52is rotated by the rotation axis56, the angle transmission error estimation part72estimates the amount of angle transmission error based on, for example, the temperatures of the gears95and96, a difference between the thermal expansion coefficients of the gears95and96, and the distance Lg2 between the reference axes of the gears95and96. The temperatures of the gears95and96are detected by, for example, the temperature sensor82. When the gear95is made of Fe and the gear96is made of Al, the difference in the thermal expansion coefficients between the gears95and96may be a difference between the thermal expansion coefficient of Al and the thermal expansion coefficient of Fe. The distance Lg2 between the reference axes is an inter-axis distance of the gears95and96at the reference temperature.

When estimating the amount of angle transmission error when the third arm53is rotated by the rotation axis57, the angle transmission error estimation part72estimates the amount of angle transmission error based on, for example, the temperatures of the gears98and99, a difference between the thermal expansion coefficients of the gears98and99, and the distance Lg3 between the reference axes of the gears98and99. The temperatures of the gears98and99are detected by, for example, the temperature sensor84. When the gear98is made of Fe and the gear99is made of Al, the difference in the thermal expansion coefficients between the gears98and99may be a difference between the thermal expansion coefficient of Al and the thermal expansion coefficient of Fe. The distance Lg3 between the reference axes is the inter-axis distance of the gears98and99at the reference temperature. The angle transmission error estimation part72also estimates the amount of angle transmission error when the fourth arm54is rotated by the rotation axis57in the same manner.

The angle error direction estimation part73estimates a direction of the angle transmission error. The angle error direction estimation part73estimates the direction of the angle transmission error when the first arm51is rotated by the rotation axis55based on the acceleration/deceleration state of the first axis motor91. The angle error direction estimation part73estimates the direction of the angle transmission error when the second arm52is rotated by the rotation axis56based on the acceleration/deceleration state of the second axis motor94in the same manner. The angle error direction estimation part73estimates the direction of the angle transmission error when the third arm53is rotated using the rotation axis57based on the acceleration/deceleration state of the third axis motor97. The direction of the angle transmission error when the fourth arm54is rotated by the rotation axis57is also estimated in the same manner.

The estimation of the direction of the angle transmission error will be described with reference toFIGS.5A and5BandFIGS.6A and6B.

FIGS.5A and5Bare views schematically illustrating postures of the substrate transfer mechanism5.FIG.5Ais a view illustrating an example of the posture of the substrate transfer mechanism5when the substrate W is located at a measurement position measured by a sensor unit6.FIG.5Bis a view illustrating an example of the posture of the substrate transfer mechanism5when the substrate W to be transferred is located at a target position.

As indicated by the broken line arrows, the link lengths of the first arm51and the second arm52are thermally expanded. Since the reference positions on the third arm53and the fourth arm54on which the substrate W is placed are set to a predetermined distance from the rotation axis57, the thermal expansion of the third arm53and the fourth arm54does not have to be taken into consideration.

At the measurement position illustrated inFIG.5A, the substrate transfer mechanism5allows the substrate W to pass over the sensor unit6in a state of accelerating the substrate W. As a result, the substrate W being transferred receives an inertial force in the direction indicated by the white arrow. The substrate transfer mechanism5causes the substrate W to be directed to the target position of the stage41in a state in which the substrate W is decelerated, and then stops the transfer of the substrate W at the target position as illustrated inFIG.5B. Therefore, the substrate W being transferred receives an inertial force in the direction indicated by the white arrow.

Here, a relationship between an acceleration/deceleration state and the error direction of the angle transmission error will be described with reference toFIGS.6A and6B.FIGS.6A and6Bare exemplary views each illustrating the error direction of the angle transmission error.FIG.6Aillustrates the error direction of the angle transmission error during acceleration of the first axis motor91.FIG.6Billustrates the error direction of the angle transmission error during deceleration of the first axis motor91. The solid arrows indicate the rotation directions of each gear.

During acceleration of the first axis motor91illustrated inFIG.6A, a primary side gear92rotates clockwise, and a secondary side gear93rotates counterclockwise. At this time, the teeth of the primary side gear92are in contact with the teeth of the secondary side gear93in a direction of pushing the teeth of the secondary side gear93due to an inertial force. As a result, an angle transmission error due to backlash occurs in the direction indicated by the white arrow.

Meanwhile, during deceleration of the first axis motor91illustrated inFIG.6B, the primary side gear92rotates clockwise, and the secondary side gear93rotates counterclockwise. At this time, the teeth of the secondary side gear93are in contact with the teeth of the primary side gear92in the direction of pushing the teeth of the primary side gear92due to an inertial force. As a result, an angle transmission error due to backlash occurs in the direction indicated by the white arrow.

In this way, the direction of the angle transmission error due to the backlash of the gears92and93which are power transmission mechanisms, varies depending on the acceleration and deceleration of the first axis motor91. The same applies to the direction of the angle transmission error due to the backlash of the gears95and96which are the power transmission mechanisms of the second axis motor94, and the gears98and99which are the power transmission mechanisms of the third axis motor97. An example of the directions of the angle transmission error are indicated by the solid arrows inFIGS.5A and5B, in which the direction of the angle transmission error changes at the measurement position inFIG.5Aand the target position inFIG.5B.

Assuming that the temperature change of the substrate transfer mechanism5during the transfer of the substrate W is sufficiently small, it may be considered that the amounts of thermal expansion of the first arm51and the second arm52and amounts of angle transmission error at the rotation axes55,56, and57at the measurement position and the transfer position are not changed.

When the substrate transfer mechanism5performs substrate transfer of receiving one substrate on one side of the stage21of the load-lock chamber2and the stage41of the processing chamber4and delivering another substrate on the other side, the transfer position correction part74corrects the misalignment of the substrate transfer mechanism5such that the transfer position of the substrate W becomes the target position. The correction amount at this time includes a displacement (thermal displacement) due to the thermal expansion of the substrate transfer mechanism5, and the thermal displacement amount stored in the transfer position correction part74is estimated by using a physical model.

That is, as described above, the substrate transfer mechanism5includes the arms51to54which are rotatably connected to each other, and the motors91,94, and97that rotate the arms51to54via the gears that are power transmission mechanisms. The physical model for estimating the amounts of thermal displacement of the holders53aand54ais expressed by an equation of the amounts of thermal expansion of the arms51to54estimated based on the temperature of the arms51to54, the angles of joints which are the connecting portions of the arms, and an angular delay amount (an amount of angle transmission error) estimated based on the temperature, and the like.

In the present embodiment, a difference between a true deviation amount between the holder53aor54aand the substrate W, in which the thermal displacement amount at a measurement position when the substrate is delivered to the stage of a transfer destination (at the time of putting) is taken into consideration, and a true deviation amount between the holder53aor54aand the substrate W, in which the thermal displacement amount at the measurement position when the substrate is received from the stage of a transfer source (at the time of getting) is taken into consideration, is reflected to a physical model for estimating the thermal displacement amount at the measurement position at the time of putting by the transfer position correction part74.

This point will be described in detail below by taking as an example a case in which the transfer source is the stage21, the transfer destination is the stage41, and the substrate W is placed on and transferred by the holder53a.

The controller7controls the substrate transfer mechanism5such that the substrate W is transferred to a target position on the stage41, and a deviation occurs at the transfer position due to the deviation when the holder53areceives the substrate W or a thermal displacement of the holder53adue to the thermal expansion of the substrate transfer mechanism5. The misalignment on the stage41is obtained from a deviation amount (X3, Y3) between the substrate W and the holder53a, which is a value detected by the sensor unit6adjacent to the processing chamber4, the thermal displacement amount (X1, Y1) of the measurement position by the sensor unit6, and the thermal displacement amount (X2, Y2) of the holder53ain the stage41.

Specifically, (X3, Y3) is the deviation amount between the reference position (center position of the holder53a) and the center position of the substrate W held by the holder53a. In addition, (X1, Y1) is a misalignment amount of the holder53adue to the thermal expansion of the substrate transfer mechanism5at the measurement position at the time of putting. (X2, Y2) appears as the misalignment of the reference position of the third arm53(the holder53a) with respect to the target position of the substrate W. The true deviation amount between the holder53aand the substrate W is obtained by taking the thermal expansion of the substrate transfer mechanism5at the measurement position into consideration. Specifically, as illustrated inFIG.7A, the true deviation amount is (X3-X1, Y3-Y1) derived from the detected value (X3, Y3) expressed as a deviation amount in setting and the thermal displacement amount (X1, Y1) at the measurement position (the misalignment amount of the holder53adue to thermal expansion at the measurement position). InFIG.7A, the center of the substrate W is indicated by O′ and the reference position is indicated by O1. In addition, in the stage41, as illustrated inFIG.7B, the deviation amount due to thermal expansion between the reference position O1 and the target position O is (X2, Y2). The deviation amount of the substrate W from the target position on the stage41of the transfer destination is obtained by adding the thermal displacement amount (X2, Y2) on the stage41to the true deviation amount (X3-X1, Y3-Y1). Therefore, the position correction amount of the holder53aat this time equals minus (−) (the true deviation amount between the holder53aand the substrate W plus the thermal displacement amount at the stage41), wherein the value thereof is (−X3-X2+X1, Y3-Y2+Y1). Therefore, it is possible to control the transfer position of the substrate W on the holder53ato the target position by controlling the first axis motor91, the second axis motor94, the third axis motor97, and the like of the substrate transfer mechanism5to correct the position of the holder53awith the above-mentioned correction amount.

As described above, the thermal displacement amount of the correction amount of the substrate transfer mechanism5is calculated by using a physical model. For example, as the physical model for obtaining X1 which is the X coordinate of the thermal displacement amount at the measurement position at the time of putting, the following Equation (1) may be used. The same applies to Y1, which is the Y coordinate.
X1=L1 cos Ω1′α1ΔT+L2 cos Ω2′α2ΔT+L3 cos Ω3′α3ΔT+L1(cos Ω1′−cos Ω1)+L2(cos Ω2′−cos Ω2)+L3(cos Ω3′−cos Ω3)  (1)

Where, L1, L2, and L3 are the link length of the first arm51, the link length of the second arm, and the link length of the third arm, respectively, as described above. α1, α2, and α3 are the linear expansion coefficient of a first link, the linear expansion coefficient of a second link, and the linear expansion coefficient of a third link, respectively (the initial values are all the same numerical values as the coefficient of thermal expansion of the material of the arms). Ω1, Ω2, and Ω3 are a first joint angle, a second joint angle, and a third joint angle (all of which are design values), respectively, at the time of putting. Ω1′, Ω2′, and Ω3′ are Ω1′=Ω1+ΔΩ1, Ω2′=Ω2+ΔΩ2, and Ω3′=Ω3+ΔΩ3, respectively, wherein ΔΩ1, ΔΩ2, and ΔΩ3 are angular delay amounts (which are proportional to ΔT) due to the increase in the inter-axis distances of gears.

However, when using a physical model for a thermal displacement amount, the consistency of the physical model becomes a problem. That is, by using the physical model, it is possible to correct the position in consideration of the thermal displacement of the substrate transfer mechanism5, but there is always a model error in the physical model. For example, the physical model of the above-described Equation (1) representing the thermal displacement at the time of putting also includes a model error. Therefore, there is also a limit to the accuracy of position correction.

In order to reduce such a model error, the transfer position correction part74of the present embodiment uses a difference between the true deviation amount between the holder53aand the substrate W, in which the thermal displacement amount at the measurement position at the time of putting is also taken into consideration, and the true deviation amount between the holder53aand the substrate W, in which the thermal displacement amount at the measurement position at the time of getting is also taken into consideration. Ideally, the true deviation amounts show the same value, as described below.

It is assumed that at the time of getting the detection value of the sensor unit6adjacent to the load-lock chamber2is (X3′, Y3′), and the thermal displacement amount at the measurement position by the sensor unit6is (X1′, Y1′). Specifically. (X3′, Y3′) is the deviation amount between the reference position (the center position of the holder53a) in the setting of the third arm53and the center position of the substrate W held by the holder53a. In addition, specifically, (X1′, Y1′) is a misalignment amount of the holder53adue to the thermal expansion of the substrate transfer mechanism5at the measurement position at the time of getting. The true deviation amount between the holder53aand the substrate W is (X3′−X1′, Y3′−Y1′) derived from the detected value (X3′, Y3′) expressed as the deviation amount in setting and the thermal displacement amount (X1′, Y1′) at the measurement position (the misalignment amount of the holder53adue to thermal expansion).

The thermal displacement amount (X1′, Y1′) at the measurement position at the time of getting may also be obtained by using a physical model. As the physical model for obtaining X1′ which is the X coordinate of the thermal displacement amount at the measurement position at the time of getting, for example, the following Equation (2) may be used.
X1′=L1 cos Θ1′α1ΔT+L2 cos Θ2′α2ΔT+L3 cos Θ3′α3ΔT+L1(cos Θ1′−cos Θ1)+L2(cos Θ2′−cos Θ2)+L3(cos Θ3′−cos Θ3)  (2)

Where, L1, L2, L3, α1, α2, and α3 are the same as those in Equation (1), and Θ1, Θ2, and Θ3 are the first joint angle, the second joint angle, and the third joint angle (all of which are design values), respectively, at the time of getting. Θ1′, Θ2′, and Θ3′ are Θ1′=Θ1+ΔΘ1, Θ2′=Θ2+ΔΘ2, and Θ3′=Θ3+ΔΘ3, respectively, wherein ΔΘ1, ΔΘ2, and ΔΘ3 are angular delay amounts (which are proportional to ΔT) due to the increase in the inter-axis distances of gears.

The true deviation amount (X3-X1, Y3-Y1) in which the thermal displacement between the holder53aand the substrate W at the time of putting and the true displacement amount (X3′−X1′, Y3′−Y1′) between the holder53aand the substrate W at the time of getting should ideally have the same value, as described above. However, the true deviation amounts do not actually have the same value, and a difference occurs therebetween. For example, regarding the X coordinates, a difference A occurs between (X3-X1) and (X3′−X1′). This is because, except for a detection error in the sensor unit6, an error occurs in the estimated thermal displacement amount due to the model error of the physical model.

Therefore, the transfer position correction part74reflects, to a physical model for calculating a thermal displacement amount at the measurement position at the time of putting, the difference between the true deviation amount between the holder53aand the substrate W at the measurement position at the time of putting (the true deviation amount at the measurement position at the time of putting) and the true deviation amount between the holder53aand the substrate W at the measurement position at the time of getting (the true deviation amount at the measurement position at the time of getting) to correct the physical model such that the model error is reduced. For example, a correction term that reflects the difference between the true deviation amount at the measurement position at the time of putting and the true deviation amount at the measurement position at the time of getting is added to the initial physical model.

As a specific example, a difference A is calculated by (the true displacement amount at the measurement position at the time of putting) minus (the true displacement amount at the measurement position at the time of getting), and A/2, which is a simple average A, is added to X1, which is the initial physical model of the thermal displacement amount at the measurement position at the time of putting to correct the physical model to X1(Ave) represented as the following Equation (3). This makes it possible to reduce the error of the physical model.
X1(Ave)=X1+A/2  (3)

As described above, the position correction amount of the substrate transfer mechanism5equals minus (−) (the true deviation amount between the holder53aand the substrate W plus the thermal displacement amount at the stage41), wherein the initial value of the X coordinate thereof is −X3−X2+X1. Therefore, X1 of the initial position correction amount is replaced with X1(Ave), and the position correction amount is calculated as −X3−X2+X1(Ave). The same applies to the Y coordinate. As a result, it is possible to correct the physical model with a small error by a simple method. This also makes it possible to improve the position correction accuracy and thus to improve the transfer accuracy of the substrate W. In this example, the initial physical model is used for the thermal displacement amount X2 used for the transfer position correction.

Alternatively, the following method may be used as another method.

In the physical models of Equations (1) and (2) above, the following Equations (4) and (5), in which an error factor β(ΔT) expressed as a function of ΔT not included in these models is added as a correction term, are used.
X1=L1 cos Ω1′α1ΔT+L2 cos Ω2′α2ΔT+L3 cos Ω3′α3 ΔT+L1(cos Ω1′−cos Ω1)+L2(cos Ω2′−cos Ω2)+L3(cos Ω3′−cos Ω3)+β(ΔT)  (4)
X1′=L1 cos Θ1′α1 ΔT+L2 cos Θ2′α2ΔT+L3 cos Θ3′α3ΔT+L1(cos Θ1′−cos Θ1)+L2(cos Θ2′−cos Θ2)+L3(cos Θ3′−cos Θ3)+β(ΔT)  (5)

In Equations (4) and (5) above, ΔΘ1 and ΔΩ21, ΔΘ2 and ΔΩ2, and ΔΘ3 and ΔΩ23 are proportional to a first inter-axis distance of gears, a second inter-axis distance of gears, and a third inter-axis distance of gears, respectively, and are calculated from the same physical amount. The same applies to L1, L2, and L3, ΔT, and α. Therefore, these parameters are fitted such that the difference A becomes the smallest. For example, these parameters are solved by using a linear programming method or the like, or parameters with a small error are derived through machine learning or the like. As the function of ΔT, one having a functional type of being proportional to ΔT, proportional to the square of ΔT, proportional to the exponent of ΔT, and so on may be used.

For example, X1(True) may be calculated as the true value of X1 by changing the arguments (the numerical values of physical amounts in the physical model) in the equation by using Equations (4) and (5) above such that the difference A equals 0, that is, (X3−X1)−(X3′−X1′)=0. In this case, fitting is performed by using a linear programming method or the like such that (X3′−X1′)−(X3-X1)=0, and the physical amounts of Equations (4) and (5) above, i.e., L1, L2, L3, Θ1′, Θ2′, Θ3″, α, β, and ΔT are determined. Then, L1, L2, L3, ΔΩ1, ΔΩ2, ΔΩ3, α, β, and ΔT obtained in this way are used as true values, and X1 (True) is calculated from an equation which is of the same type as Equations (4) and (5). X1(True) is an equation derived by fitting such that the difference A=0 is satisfied, and has a very small error.

When X1(True) is used, it is possible to correct the physical model of the above-mentioned thermal displacement amount X2 used for the transfer position correction. At this time, it is possible to estimate X2(True) by using the physical amounts used when estimating X1(True) as true values, and calculating X2(True) with a physical model obtained by adding, to the initial physical model of X2, an error factor β(ΔT) expressed as a function of ΔT not included in this mode.

It is possible to calculate X2(True) by the following Equation (6) by using L1, L2, L3, ΔΘ1, ΔΘ2, ΔΘ3, α, β, and ΔT obtained by the calculation of X1(True) as true values.
X2(True)=L1 cos ξ1′αΔT+L2 cos ξ2′αΔT+L3 cos ξ3′αΔT+L1(cos ξ1′−cos ξ1)+L2(cos ξ2′−cos ξ2)+L3(cos ξ3′−cos ξ3)+β(ΔT)  (6)

Where, ξ1, ξ2, and ξ3 are a first joint angle, a second joint angle, and a third joint angle (all of which are design values), respectively. ξ1′, ξ2′, and ξ3′ are ξ1′=ξ1+Δξ1, ξ2′=ξ2+Δξ2, and ξ3′=ξ3+Δξ3, respectively, wherein Δξ1, Δξ2, and Δξ0 are angular delay amounts (which are proportional to ΔT) due to the increase in the inter-axis distances of gears, and wherein Δξ1=ΔΩ1, Δξ2=ΔΩ2, and Δξ3=ΔΩ3.

X2(True) is obtained by the same equation as X1(True), and has a very small error like X1(True).

As described above, the position correction amount of the substrate transfer mechanism5is expressed as minus (−) (the true deviation amount between the holder53aand the substrate W plus the thermal displacement amount at the stage41), wherein the initial value of the X coordinate thereof is −X3−X2+X1. Therefore, X1 of the initial position correction amount is replaced with X1(True), X2 is replaced with X2(True), and the position correction amount is calculated as −X3−X2(True)+X1 (True). The same applies to the Y coordinate. In the case of this example, by correcting X1 to X1(True), it is possible to reduce the error of the thermal displacement amount at the measurement position as well as the error of the thermal displacement amount on the stage. Thus, it is possible to further improve the accuracy in the position correction of the substrate transfer mechanism.

<Substrate Transfer Method>

Next, an example of a substrate transfer method using the substrate transfer mechanism5will be described in detail.

Here, a case in which the substrate W is transferred from the stage21of the load-lock chamber2to the stage41of the processing chamber4by the holder53aof the third arm53will be described.

FIG.8is a flowchart illustrating an example of the substrate transfer method.

First, the substrate W on the stage21of the load-lock chamber2is received by the holder53aof the substrate transfer mechanism5(step ST1).

Subsequently, while retracting the holder53athat holds the substrate W, the substrate W is caused to pass through the sensor unit6(the first measurement part) adjacent to the load-lock chamber2, and a true deviation amount between the holder53aand the substrate W is measured in which a thermal displacement amount at the measurement position at the time of getting is taken into consideration (step ST2). As described above, the true deviation amount at this time is (X3′−X1′, Y3′−Y1′) derived from the detected value (X3′, Y3′) expressed as the deviation amount in setting and the thermal displacement amount (X1′, Y1′) at the measurement position (the misalignment amount of the holder53adue to thermal expansion).

Subsequently, while the substrate W is transferred toward the processing chamber4and the holder53athat holds the substrate W extends toward the stage41, the substrate W is caused to pass through the sensor unit6(the second measurement part) adjacent to the processing chamber4and the true deviation amount between the holder53aand the substrate W in which a thermal displacement amount at the measurement position at the time of putting is taken into consideration (step ST3). As described above, the true deviation amount at this time is (X3-X1, Y3-Y1) derived from the detected value (X3, Y3) expressed as the deviation amount in setting and the thermal displacement amount (X1, Y1) at the measurement position (the misalignment amount of the holder53adue to thermal expansion).

Subsequently, the difference between the true deviation amount at the measurement position at the time of putting and the true displacement amount at the measurement position at the time of getting is reflected to a physical model for calculating the thermal displacement amount at the measurement position at the time of putting to correct the physical model so that the model error is reduced (step ST4).

Subsequently, the position correction amount of the holder53aon the stage41is calculated from the thermal displacement amount of the holder53aat the measurement position at the time of putting, wherein the thermal displacement amount is estimated with the corrected physical model, the deviation amount between the holder53aand the substrate W, wherein the deviation amount is a value detected by the sensor unit6at the time of putting, and the thermal displacement amount of the holder53aon the stage41(step ST5).

Subsequently, based on the correction amount calculated in step ST5, the controller7controls the substrate transfer mechanism5to correct the position of the holder53aand deliver the substrate W on the holder53ato the stage41(step ST6).

As described above, in the present embodiment, the difference between the true deviation amount at the measurement position at the time of putting and the true deviation amount at the measurement position at the time of getting is reflected to the physical model for calculating the thermal displacement amount at the measurement position at the time of putting to correct the physical model and to reduce the error of the physical model. As a result, it is possible to improve the position correction accuracy with respect to the misalignment of the substrate transfer mechanism5due to thermal expansion, and to transfer the substrate W to the target position with high accuracy.

Subsequently, a specific example of a process of correcting the physical model in step ST4and the step of calculating the position correction amount of the substrate transfer mechanism5in step ST5will be described.

A first example is a case illustrated inFIG.9in which the above-mentioned X1(Ave) is used.

First, the difference A is obtained by (the true deviation amount at the measurement position at the time of putting) minus (the true deviation amount at the measurement position at the time of getting), and according to Equation (3) above, X1(Ave) obtained by adding A/2 to X1 as a correction term is calculated (step ST4-1).

Subsequently, the correction amount is calculated as the correction amount (X coordinate) of the substrate transfer mechanism5that equals −X3-X2+X1(Ave) (step ST5-1).

In this way, since it is only necessary to take and average the difference between the true deviation amount at the measurement position at the time of putting and the true deviation amount at the measurement position at the time of getting, it is possible to easily correct the physical model with a small error. This also makes it possible to improve the position correction accuracy and thus to improve the transfer accuracy of the substrate W.

A second example is a case illustrated inFIG.10in which the numerical values of physical amounts in a physical model are changed by using the error factor β(ΔT) represented in Equations (4) and (5) above.

First, for example, arguments in an equation (the numerical values of physical amounts in the physical model) are changed by using Equations (4) and (5) above so that the difference A equals 0, that is, (X3−X1)−(X3′−X1′)=0, the physical amounts are estimated by using a linear programming method or the like, and X1(True) is calculated as the true value of X1 by using the estimated physical amounts as true values in the same equations (step ST4-11).

Subsequently, X2(True) is calculated by Equation (6) above by using, as true values, L1, L2, L3, ΔΘ1, ΔΘ2, ΔΘ3, α, β, and ΔT obtained through the calculation of X1(True) (step ST4-12).

Subsequently, the correction amount is calculated as the correction amount (X coordinate) of the substrate transfer mechanism5that equals −X3-X2(True)+X1(True) (step ST5-11).

In this example, by changing the numerical values of physical amounts in the physical model and solving (X3−X1)−(X3′−X1′)=0, it is possible to derive X1(True), which is a physical model with a small error, and to improve the accuracy. Since it is possible to correct not only the thermal displacement amount of the measurement position but also the physical model of the thermal displacement amount of the stage41, it is possible to further improve the position correction accuracy for the misalignment of the substrate transfer mechanism5.

Subsequently, another example of the substrate transfer method will be described in detail.

Here, similarly, a case in which the substrate W is transferred from the stage21of the load-lock chamber2to the stage41of the processing chamber4will be described.

FIG.11is a flowchart illustrating another example of the substrate transfer method.

First, as in step ST1, the substrate W on the stage21of the load-lock chamber2is received by the holder53aof the substrate transfer mechanism5(step ST11).

Subsequently, as in step ST2, while retracting the holder53athat holds the substrate W, the substrate W is caused to pass through the sensor unit6(the first measurement part) adjacent to the load-lock chamber2, and a true deviation amount between the holder53aand the substrate W is measured in which a thermal displacement amount at the measurement position at the time of getting is taken into consideration (step ST12).

Subsequently, as in step ST3, while the substrate W is transferred toward the processing chamber4and the holder53athat holds the substrate W extends toward the stage41, the substrate W is caused to pass through the sensor unit6(the second measurement part) adjacent to the processing chamber4and the true deviation amount between the holder53aand the substrate W in which a thermal displacement amount at the measurement position at the time of putting is taken into consideration (step ST13).

Subsequently, the difference between the true deviation amount at the measurement position at the time of putting and the true displacement amount at the measurement position at the time of getting is reflected to a physical model for calculating the thermal displacement amount at the measurement position at the time of putting to correct the physical model so that the error of the model is reduced, and at that time, fitting is performed by changing the numerical values of the physical amounts in the physical model and the physical amounts are estimated (step ST14).

Here, for example, a physical model obtained by adding, to, for example, the initial models represented in Equations (4) and (5) represented in the second example of the above-described specific example, an error factor expressed as a function of temperature, which is not included in the initial physical models, is used. Then, the numerical values of the physical amounts in the physical model (e.g., an arm length, an arm angle, a thermal expansion coefficient, a temperature change, and the like) are changed such that the difference A expressed by (the true deviation amount at the measurement position at the time of putting) minus (the true deviation amount at the measurement position at the time of getting) becomes the smallest, preferably (X3−X1)−(X3′−X1′)=0. The physical amounts are estimated by using a linear programming method or the like, and X1(True) is calculated by the same equation by using the estimated physical amounts as true values. Then, for the thermal displacement amount X2, a physical model obtained by adding, to the initial physical model represented in Equation 6 above, an error factor expressed as a function of temperature, which is not included in this model, is also used. By using the physical amounts used to obtain X1(True) as a true value, X2(True) is calculated as the true value of X2. These procedures may be performed, for example, in the same manner as in the second example of the above-mentioned specific example.

Subsequently, the position correction amount of the holder53aon the stage41is calculated from the thermal displacement amount of the holder53aat the measurement position at the time of putting, wherein the thermal displacement amount is estimated with the corrected physical model, the deviation amount between the holder53aand the substrate W, wherein the deviation amount is a value detected by the sensor unit6at the time of putting, and the thermal displacement amount of the holder53aon the stage41(step ST15).

Subsequently, based on the correction amount calculated in step ST15, the controller7controls the substrate transfer mechanism5to correct the position of the holder53aand deliver the substrate W on the holder53ato the stage41(step ST16).

Subsequently, an estimated physical amount (parameter) and a temperature are stored as one set in the storage device of the controller7(step ST17). Such data storage may be performed each time the substrate W is transferred, or may be performed after transferring a plurality of substrates. Physical amounts (parameters) and temperatures may be stored in a temperature-to-physical amount table, and the table may be updated each time data is entered. Then, the physical amounts may be estimated from this table. However, when an estimation result deviates significantly from the table of physical amounts, an estimated physical amount may be determined by the balance between a residue and an amount of deviation from the table. Instead of using the table, a physical amount may be estimated by using a neural network or the like.

By storing the physical amount (parameter) and the temperature as one set in this way, it is possible to correct a physical model by performing feedback with respect to the physical model held by the controller7. Therefore, even if an initial physical model is not accurate, it is possible to improve the accuracy of the physical model, and it is possible to perform position correction with high accuracy with respect to the misalignment of the substrate transfer mechanism5due to thermal expansion. In addition, it is possible to change a physical model by the system or the substrate transfer mechanism, and it becomes possible to cope with secular variation and machine difference.

Other Applications

Although embodiments have been described above, it should be considered that the embodiments disclosed herein are exemplary in all respect and are not restrictive. The embodiments described above may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims.

For example, in the above-described embodiments, the case in which the substrate W is transferred from the stage21of the load-lock chamber2to the stage41of the processing chamber4by the substrate transfer mechanism5has been described, but the present disclosure is not limited thereto. The substrate W may be transferred from the stage41to the stage21. In addition, in the above-described embodiments, the substrate transfer between the load-lock chamber and the processing chamber in the substrate transfer system for performing vacuum transfer has been described, but the present disclosure is not limited thereto.

According to the present disclosure, a substrate transfer method and a substrate transfer system capable of transferring a substrate to a target position with high accuracy by a substrate transfer mechanism are provided.