JP5517741B2 - Substrate transfer method - Google Patents

Description

  The present invention comprises a film thickness measuring device for measuring the film thickness of a substrate such as a semiconductor wafer, a glass substrate for PDP, a magnetic disk substrate, or a photomask substrate, and a transport robot for transporting the substrate. The present invention relates to a substrate transfer method for transferring a substrate by a transfer robot while transferring the substrate between a measuring instrument and a transfer robot.

  Conventionally, in a polishing apparatus for polishing a substrate surface, a film thickness measuring device that measures the film thickness of the substrate before and after polishing the substrate surface, for example, between a film thickness measuring device and a cassette, and a film thickness measuring device And a transfer robot that transports the substrate by traveling between the substrate and the mounting table for transporting the substrate to the next processing unit, while delivering the substrate between the film thickness measuring instrument and the transport robot 2. Description of the Related Art A substrate having a substrate transport system that transports a substrate is known.

  For example, a film thickness measuring instrument such as ITM is generally expensive. For this reason, a polishing apparatus is usually provided with one film thickness measuring instrument. The film thickness measuring device outputs a film thickness measurement end signal when the film thickness measurement for the substrate carried into the inside is generally completed, and the transfer robot completes the film thickness measurement output from the film thickness measuring device. In response to the signal, it is controlled to start the conveying operation. That is, the transfer robot stands by at a place away from the film thickness measuring device until a film thickness measurement end signal is output from the film thickness measuring device. For this reason, if the waiting time of the transfer robot is deleted or reduced, the throughput of the entire polishing apparatus can be improved.

  Unprocessed substrates are unloaded from the cassette in advance and kept waiting in front of the chamber. After the processing is completed, the unprocessed substrates are set in the chamber, and then the processed substrates are unloaded from the chamber and stored in the cassette. It has been proposed to shorten the processing tact by performing substrate processing and substrate replacement partially in parallel by controlling the transfer device (see Patent Document 1).

Japanese Patent No. 3174691

  For example, in a polishing apparatus equipped with a single film thickness measuring device, the film thickness of an unpolished substrate is taken between the removal of the unpolished substrate from the cassette by the transfer robot and the return of the polished substrate to the cassette by the transfer robot. If the film thickness measurement is performed twice with the film thickness measurement device in total, that is, the measurement of the film thickness of the polished substrate, the substrate conveyance is limited when the film thickness of the substrate after polishing is measured. Here, as described above, when the transfer robot is controlled so as to start the transfer operation in response to the film thickness measurement end signal output from the film thickness measuring device, useless time such as a standby time is generated in the transfer robot. To do. For this reason, the throughput of the polishing apparatus as a whole is lower than that of a polishing apparatus that does not include a film thickness measuring device.

  In the invention described in Patent Document 1, the transfer device is controlled so that an unprocessed substrate is unloaded from the cassette in advance and is placed on standby in front of the chamber. However, regardless of the processing time of the substrate in the chamber. The operation of the transfer device is controlled, and therefore, the operation of the transfer device is not controlled according to the processing status of the substrate.

  The present invention has been made in view of the above circumstances, and the substrate transfer of the transfer robot is performed so as to eliminate or reduce the waiting time of the transfer robot that transfers the substrate to and from the film thickness measuring device. An object of the present invention is to provide a substrate transfer method capable of improving the throughput of the entire apparatus by controlling the operation.

One aspect of the present invention is a substrate transfer method for transferring a substrate by the transfer robot while transferring a substrate between the film thickness measuring device for measuring the thickness of the substrate, the film thickness measuring device, one From the total number of measurement points at which film thickness measurement is performed with respect to the substrate of the substrate, the number of measurement points at which film thickness measurement was actually performed with the film thickness measurement device is subtracted from the substrate carried inside. Once at the measurement points of the measurement points previously designated unmeasured, and outputs the pre-termination warning signal starts the substrate carrying operation by receiving the pre-termination warning signal outputted from the thickness measuring device A substrate transfer method comprising controlling the transfer robot as described above.

  For transporting to start the substrate transport operation in response to a prior termination notice signal output from the film thickness meter for a predetermined time (prior time) before the end of film thickness measurement for the substrate loaded into the film thickness meter By controlling the robot, before the film thickness measurement by the film thickness measuring device for the substrate carried into the inside is completed, for example, the film thickness unmeasured substrate to be measured next is received by the transfer robot. It is transported until just before delivery to the measuring instrument, and when the film thickness measurement of the substrate by the film thickness measuring instrument is completed, the substrate that has not been measured is handed over to the film thickness measuring instrument, and the film thickness measured substrate is transferred from the film thickness measuring instrument. Can receive. Thereby, it is possible to improve the throughput of the entire apparatus by deleting or reducing the useless waiting time of the transfer robot.

  When the number of unmeasured measurement points reaches the number of measurement points specified in advance, the timing to output the advance end warning signal from the film thickness measuring device is arbitrarily specified by outputting the advance end warning signal from the film thickness measuring device. can do. As a result, the film thickness measuring time by the film thickness measuring instrument can be flexibly accommodated to fluctuate depending on the film thickness measuring condition (recipe), and the film thickness measuring instrument will notify the end in advance at the optimal timing under the film thickness measuring condition. A signal can be output.

In a preferred aspect of the present invention, the film thickness measuring device is obtained by monitoring, the film thickness measuring time for the previously processed substrate and the robot transport required for the transport robot to transport the substrate to the film thickness measuring device. and time and based on, you and outputting the pre-termination warning signal.
In a preferred aspect of the present invention, the film thickness measurement is performed on a predetermined number of substrates, and the film thickness measurement time of the predetermined number of substrates is divided by the number of the substrates to obtain an average film thickness measurement time. The robot transport time when the predetermined number of substrates are transported to the film thickness measuring instrument is divided by the number of substrates to obtain an average robot transport time, and the average film thickness measurement time is less than the average robot transport time. If it is long, subtract the average robot transport time from the average film thickness measurement time, and when the time determined by the subtraction from the start of the film thickness measurement, the advance end warning signal is output, When the average film thickness measurement time is equal to or less than the average robot conveyance time, the advance end notice signal is output simultaneously with the start of the film thickness measurement.
In a preferred aspect of the present invention, every time the film thickness measurement for the predetermined number of substrates is completed, an average value of the film thickness measurement time and the robot transport time is obtained, and the film thickness measuring device is based on the average value. The timing for outputting the advance end warning signal is determined.
A preferred aspect of the present invention is to obtain an average value of the film thickness measurement time and the robot measurement time for the predetermined number of substrates every time the film thickness measurement for one substrate is completed, and based on the average value, the film The thickness measuring device determines a timing for outputting the advance notice signal.

  The film thickness measurement time and the robot transfer time required for the transfer robot to transfer the substrate to the film thickness measurement device are constantly monitored, and the film thickness measurement device is based on the film thickness measurement time and the robot transfer time. By outputting the advance end warning signal from, it is possible to know whether the process has changed, and the timing to output the advance end warning signal from the film thickness meter according to the change in the film thickness measurement time of the substrate. It can be adjusted automatically.

  According to the present invention, the substrate carrying operation is started in response to the advance end notice signal output from the film thickness measuring device before the predetermined time before the film thickness measurement for the substrate carried into the film thickness measuring device is completed. By controlling the transfer robot, it is possible to eliminate or reduce the unnecessary waiting time of the transfer robot that transfers the substrate and delivers the substrate to and from the film thickness measuring instrument, thereby improving the throughput of the entire apparatus. it can.

1 is an overall layout diagram showing a polishing apparatus to which a substrate carrying method of the present invention is applied. It is a schematic diagram which expands and shows the grinding | polishing part of the grinding | polishing apparatus of FIG. FIG. 2 is a control block diagram of the polishing apparatus in FIG. 1. It is a figure attached | subjected to description of the conventional general control example of the transfer robot which transfers a board | substrate between a funnel, ITM, a mounting base, and a washing machine, and the control example of this invention. It is a figure attached | subjected to description of the conventional general control example of the transfer robot which transfers a board | substrate between a funnel, ITM, a mounting base, and a washing machine, and the control example of this invention. (A) is a figure which shows the relationship between the film thickness measurement by ITM in the conventional control example, and the board | substrate conveyance operation by the robot for conveyance, (b) is the film thickness measurement by ITM and the object for conveyance in the control example of this invention. It is a figure which shows the relationship with the board | substrate conveyance operation by a robot. It is a figure which shows the relationship between the film thickness measurement by ITM, and the board | substrate conveyance operation | movement by the robot for conveyance when the timing which ITM outputs a prior termination notice signal is too early. It is a figure which shows the film thickness measurement time which ITM requires for film thickness measurement, and the robot conveyance time until a robot for conveyance receives a film thickness measurement completion signal or a prior completion notice signal from ITM, and delivers a board | substrate to ITM.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following example, an example is shown in which the substrate transport method of the present invention is applied to a polishing apparatus that flatly polishes the surface of a substrate such as a semiconductor wafer.

  FIG. 1 is an overall layout view of a polishing apparatus provided with a substrate transfer system to which a substrate transfer method of the present invention is applied. As shown in FIG. 1, the polishing apparatus includes four load ports 203 a to 203 d on which cassettes 204 each containing a plurality of substrates such as semiconductor wafers are placed. A travel rail 200 is provided along the load ports 203a to 203d, and a transport robot 202 having two hands is movably disposed on the travel rail 200. An ITM (film thickness measuring device) 224, which will be described later, is disposed adjacent to the traveling rail 200, and a mounting table 206 is disposed on the opposite side of the load ports 203a to 203d across the traveling rail 200. The hand of the transfer robot 202 can access the cassettes 204, the ITM 224, and the mounting table 206 on the load stages 203a to 203d.

  A transfer robot 208 is disposed between the mounting table 206 and the rotary transporter 210. Then, by holding the substrate on the rotary transporter 210 on the polishing table 100 while being held by the top ring 1 described later, a plurality of substrates can be polished continuously.

  In the polishing apparatus, the first cleaning machines 214a and 214b and the second cleaning machines 212a and 212b for cleaning and drying the polished substrate, the polishing tables 100 and 216 for polishing the substrate surface, and the dressing of the polishing tables 100 and 216 are performed. Dressers 218 and 220 to be performed, and a water tank 222 for cleaning the dresser 218 are provided. In addition, by switching a plurality of polishing liquids and a plurality of polishing conditions (polishing recipes), it is also possible to perform two-step polishing or more than one-step polishing with one polishing table 100.

  The polishing apparatus is provided with an ITM (In-line Thickness Monitor) 224 as a film thickness measuring device for measuring the film thickness of a film to be polished on the substrate surface that has been subjected to cleaning and drying treatment before polishing or after polishing. In this example, as shown in FIG. 1, before the transfer robot 202 stores the polished substrate (polished substrate) in the cassette 204 on the extended line of the traveling rail 200, or the transfer robot 202 before the polishing. After the substrate (unpolished substrate) is taken out from the cassette 204 (In-line), an optical signal incident and reflected on the substrate surface by optical means is used to generate an insulating film such as an oxide film on the substrate surface such as a semiconductor wafer. An ITM (film thickness measuring instrument) 224 for measuring the film thickness and the polished state of the copper film or the barrier film of the conductive film is disposed.

  The polishing device monitors sensor signals and measurement values to confirm that the conductive film on the surface of the substrate is removed except for necessary areas such as the wiring part or the insulating film is removed during and / or after polishing the substrate. Thus, it is possible to detect and determine the polishing conditions of each stage in the multi-stage polishing process and the end point of the polishing process, and repeat an appropriate polishing process. The ITM 224 can measure the film thickness of the substrate, whereby the polishing result at a specific portion of the substrate and the overall polishing result of the substrate can be examined.

  The polishing unit of the polishing apparatus holds the substrate and presses it against the polishing surface on the polishing table, thereby polishing the surface of the substrate flatly. FIG. 2 shows details of the polishing section of the polishing apparatus shown in FIG. As shown in FIG. 2, below the top ring 1, a polishing table 100 having a polishing pad (polishing cloth) 101 attached on the upper surface is installed. A polishing liquid supply nozzle 102 is installed above the polishing table 100, and a polishing liquid (slurry) Q is supplied onto the polishing pad 101 on the polishing table 100 by the polishing liquid supply nozzle 102. The top ring 1 can also be moved to a position immediately above a polishing table 216 (see FIG. 1) having a polishing pad (polishing table) 217 attached to the upper surface. The polishing table 216 is configured to perform a so-called scroll operation, and a polishing liquid supply unit (not shown) for supplying a polishing liquid onto the polishing pad 217 is provided inside the polishing table 216.

  In the polishing apparatus shown in FIG. 1, with the top ring 1 holding the substrate W, the polishing table 100 performs the first stage polishing on the substrate W, and the polishing table 216 performs the second stage polishing on the substrate W. Yes. For this reason, the polishing pad 101 of the polishing table 100 has a low level difference elimination characteristic with respect to the surface of the film to be polished formed on the uppermost layer of the substrate W such as an oxide film, but has a high polishing rate for the film to be polished. A liquid (slurry) Q is supplied. The polishing pad 217 of the polishing table 216 has a low polishing rate with respect to the polishing target film formed on the uppermost layer of the substrate W such as an oxide film, but has a high step resolution capability (slurry) with respect to the surface of the polishing target film. Is supplied.

  There are various types of polishing pads 101 and 217 available on the market. For example, SUBA800, IC-1000, IC-1000 / SUBA400 (double-layer cloth) manufactured by Rodel, and Surfin xxx-5 manufactured by Fujimi Incorporated. , Surfin 000, etc. SUBA800, Surfin xxx-5, and Surfin 000 are nonwoven fabrics in which fibers are hardened with urethane resin, and IC-1000 is a hard foamed polyurethane (single layer). The polyurethane foam is porous (porous) and has a number of fine recesses or holes on the surface thereof. The polishing pads 101 and 217 are basically consumable members and are worn away by polishing the surface of the substrate. In the actual polishing process, when the polishing pads 101 and 217 have a predetermined thickness or when the polishing rate is reduced, the new polishing pads 101 and 217 are replaced.

  As shown in FIG. 2, the top ring 1 is connected to a top ring drive shaft 11 via a universal joint 10, and the top ring drive shaft 11 is fixed to a top ring head 110. 111. The top ring drive shaft 11 is moved up and down by the top ring air cylinder 111 to raise and lower the entire top ring 1 and press the retainer ring 3 fixed to the lower end of the top ring body 2 against the polishing tables 100 and 216. The top ring air cylinder 111 is connected to the compressed air source 120 and can adjust the fluid pressure such as the air pressure of the pressurized air supplied to the top ring air cylinder 111. Thereby, the pressing force for pressing the polishing pads 101 and 217 with the substrate W held by the retainer ring 3 can be adjusted.

  The top ring drive shaft 11 is connected to the rotary cylinder 112 via a key (not shown). The rotating cylinder 112 includes a timing pulley 113 on the outer periphery thereof. A top ring motor 114 as a rotation drive unit is fixed to the top ring head 110, and the timing pulley 113 is connected to a timing pulley 116 provided on the top ring motor 114 via a timing belt 115. Yes. Accordingly, when the top ring motor 114 is rotationally driven, the rotary cylinder 112 and the top ring drive shaft 11 rotate together via the timing pulley 116, the timing belt 115, and the timing pulley 113, and the top ring 1 rotates. The top ring head 110 is supported by a top ring head shaft 117 fixedly supported on a frame (not shown).

  The output signal from the ITM 224 is input to the control unit 400 as shown in FIG. As shown in FIG. 3, the control unit 400 has a desired shape or the like based on an input from an input unit 401 such as a man-machine interface such as an operation panel or an input from a host computer 402 that performs various data processing. The polishing apparatus is controlled so that the substrate is polished at a target polishing rate (polishing amount) so as to have a target profile. The control unit 400 also controls the operation of the transfer robot 202 as shown in FIG.

  In the polishing apparatus shown in FIG. 1, the substrates accommodated in the cassettes 204 placed on the load ports 203 a to 203 d are sequentially transferred to the rotary transport 210 by the transfer robots 202 and 208 and are held by the top ring 1. . Then, the first-stage polishing by the polishing table 100 and the second-stage polishing by the polishing table 216 are performed on the substrate W held by the top ring 1. Then, the polished substrate is cleaned by the first cleaner 214a or 214b and the second cleaner 212a or 212b, dried, and returned to the cassette 204.

  Prior to this polishing process, the substrate (unpolished substrate) in the cassette 204 before being polished is transferred from the cassette 204 to the ITM 224 by the transfer robot 202, and the film to be polished formed on the uppermost layer of the unpolished substrate by this ITM 224. The thickness of the oxide film or the like is measured. Then, the unpolished substrate whose thickness has been measured is transferred from the ITM 224 to the mounting table 206 by the transfer robot 202.

  The unpolished substrate transported to the mounting table 206 is transported to the rotary transporter 210 by the transport robot 208 and held by the top ring 1. First, using the polishing table 100, the first stage polishing is performed on the substrate W under preset polishing conditions. That is, as shown in FIG. 2, while the substrate W held by the top ring 1 is pressed against the polishing pad 101 of the polishing table 100 with a predetermined pressing force, the polishing table 100 and the top ring 1 are rotated and simultaneously polished. The polishing liquid Q is supplied from the liquid supply nozzle 102 to the polishing pad 101 of the polishing table 100. Then, for example, without removing the oxide film or the like completely, the first-stage polishing is finished in a state where the oxide film or the like remains slightly.

  Next, the substrate W that has been polished in the first stage is moved to a position directly above the polishing table 216 while being held by the top ring 1, and the substrate W is used under the polishing conditions set in advance using the polishing table 216. The second stage of polishing is performed. That is, while the substrate W held by the top ring 1 is pressed against the polishing pad 217 of the polishing table 216 with a predetermined pressing force, the polishing table 216 and the top ring 1 are rotated, and at the same time, the polishing liquid formed on the polishing table 216 The polishing liquid is supplied to the polishing pad 217 of the polishing table 216 through the supply unit. In this second polishing, for example, the oxide film on the barrier film is completely polished, and the barrier film is further polished to the polishing target.

  The transfer robot 208 sequentially transfers the substrate after the second stage polishing (polished substrate) from the rotary transporter 210 to the first cleaning machine 214a or 214b and further to the second cleaning machine 212a or 212b. The substrate is cleaned and dried. The transfer robot 202 receives the polished substrate from the second cleaning machine 212a or 212b and transfers it to the ITM 224. The ITM 224 measures the thickness of the barrier film or the like on the polished substrate surface. The transfer robot 202 receives the polished substrate after the film thickness measurement from the ITM 224 and returns it to the cassette 204.

Next, with reference to FIGS. 4 and 5, load port 203c, ITM224, conventional manner common transfer robot 202 for transferring substrates between each other of the mounting table 206 and the second washer 212a, 212b A control example will be described.

  First, when a polished substrate is carried into the ITM 224 from the second cleaning machine 212a or 212b by the transfer robot 202 and the film thickness of the polished substrate is measured in the ITM 224, the transfer robot 202 is not polished. Since the substrate has been received from the ITM 224 and transferred to the mounting table 206, as shown by a solid line in FIG.

  Then, when the ITM 224 finishes measuring the film thickness of the substrate and a film thickness measurement end signal is output from the ITM 224 and input to the control unit 400, the control unit 400 outputs an operation start signal to the transfer robot 202. Upon receiving the operation start signal from the control unit 400, the transfer robot 202 first moves to a position B accessible to the load port 203c as shown by an arrow (1) in FIG. An unpolished substrate is received from 204 (see FIG. 1), and then moved to a position C accessible to the ITM 224 as indicated by an arrow (2) in FIG. The transfer robot 202 delivers the unpolished substrate to the ITM 224 at this position C and receives the polished substrate from which the film thickness measurement has been completed from the ITM 224.

  Next, as shown by an arrow (3) in FIG. 4, the transfer robot 202 moves to the position B accessible to the cassette 204 of the load port 203c and finishes the film thickness measurement received from the ITM 224. Is returned to the cassette 204 of the load port 203c. Then, the transfer robot 202 waits until the next operation start signal is input at this position B.

  When the unpolished substrate is carried into the ITM 224 from the cassette 204 of the load port 203c by the transfer robot 202 and the film thickness of the unpolished substrate is measured in the ITM 224, the transfer robot 202 finishes the film thickness measurement. Since the polished substrate is received from the ITM 224 and transferred to the cassette 204 of the load port 203c, it stands by at a position B accessible to the cassette 204 of the load port 203c as shown by a solid line in FIG.

  Then, when the ITM 224 finishes measuring the film thickness of the substrate and a film thickness measurement end signal is output from the ITM 224 and input to the control unit 400, the control unit 400 outputs an operation start signal to the transfer robot 202. The transfer robot 202 receives the operation start signal from the control unit 400, and first, as shown by an arrow (1) in FIG. 5, the position D accessible to the second cleaning machine 212a (or the second cleaning machine 212b). To receive the dried polished substrate from the second cleaning machine 212a (or the second cleaning machine 212b), and then, as shown by the arrow (2) in FIG. 5, the position C accessible to the ITM 224. Move to. At this position C, the transfer robot 202 delivers the dried polished substrate to the ITM 224 and receives the unpolished substrate whose film thickness measurement has been completed from the ITM 224.

  Next, as shown by an arrow (3) in FIG. 5, the transfer robot 202 moves to a position A accessible to the mounting table 206, and the unpolished substrate that has received the film thickness measurement received from the ITM 224 is mounted on the mounting table. Deliver to 206. Then, the transfer robot 202 stands by until the next operation start signal is input at this position A.

  To summarize the above-described conventional control example, as shown in FIG. 6A, the transfer robot 202 starts the film thickness measurement for the substrate after the ITM 224 finishes the film thickness measurement for the previous substrate. (1) Transfer the unpolished substrate to the position C accessible to the ITM 224, (2) Deliver the unmeasured substrate to the ITM 224 at the position C, and (3) The substrate from the ITM 224 at the position C. The following three operations are performed.

Next, a control example of with reference to FIGS. 4 and 5, load port 203c, ITM224, mounting table 206 and the second cleaning machine 212a, the present invention of the transfer robot 202 for transferring substrates between 212b mutual Will be described.

  First, when a polished substrate is carried into the ITM 224 from the second cleaning machine 212a or 212b by the transfer robot 202 and the film thickness of the polished substrate is measured in the ITM 224, the transfer robot 202 is not polished. Since the substrate has been received from the ITM 224 and transferred to the mounting table 206, as shown by a solid line in FIG.

  Then, when the ITM 224 outputs a prior completion notice signal from the ITM 224 and inputs it to the control unit 400 before the ITM 224 finishes the film thickness measurement of the substrate, the control unit 400 starts to operate the transfer robot 202. Output a signal. Upon receiving the operation start signal from the control unit 400, the transfer robot 202 first moves to a position B accessible to the load port 203c as shown by an arrow (1) in FIG. An unpolished substrate is received from 204 (see FIG. 1), and then moved to a position C accessible to the ITM 224 as indicated by an arrow (2) in FIG.

  When the ITM 224 finishes measuring the film thickness of the substrate and outputs a film thickness measurement end signal from the ITM 224 and is input to the control unit 400, the transfer robot 202 delivers the unpolished substrate to the ITM 224 at this position C, Thereafter, the polished substrate whose film thickness measurement has been completed is received from the ITM 224. Next, as shown by an arrow (3) in FIG. 4, the transfer robot 202 moves to the position B accessible to the cassette 204 of the load port 203c and finishes the film thickness measurement received from the ITM 224. Is returned to the cassette 204 of the load port 203c. Then, the transfer robot 202 waits until the next operation start signal is input at this position B.

  When the unpolished substrate is carried into the ITM 224 from the cassette 204 of the load port 203c by the transfer robot 202 and the film thickness of the unpolished substrate is measured in the ITM 224, the transfer robot 202 finishes the film thickness measurement. Since the polished substrate is received from the ITM 224 and transferred to the cassette 204 of the load port 203c, it stands by at a position B accessible to the cassette 204 of the load port 203c as shown by a solid line in FIG.

  Then, when the ITM 224 outputs a prior completion notice signal from the ITM 224 and inputs it to the control unit 400 before the ITM 224 finishes the film thickness measurement of the substrate, the control unit 400 starts to operate the transfer robot 202. Output a signal. The transfer robot 202 receives the operation start signal from the control unit 400, and first, as shown by an arrow (1) in FIG. 5, the position D accessible to the second cleaning machine 212a (or the second cleaning machine 212b). To receive the dried polished substrate from the second cleaning machine 212a (or the second cleaning machine 212b), and then, as shown by the arrow (2) in FIG. 5, the position C accessible to the ITM 224. Move to.

  Then, when the ITM 224 finishes measuring the film thickness of the substrate and a film thickness measurement end signal is output from the ITM 224 and input to the control unit 400, the transfer robot 202 reads the dried polished substrate at this position C. The unpolished substrate that has been delivered to the ITM 224 and has finished film thickness measurement is received from the ITM 224. Next, as shown by an arrow (3) in FIG. 5, the transfer robot 202 moves to a position A accessible to the mounting table 206, and the unpolished substrate that has received the film thickness measurement received from the ITM 224 is mounted on the mounting table. Deliver to 206. Then, the transfer robot 202 stands by until the next operation start signal is input at this position A.

  Summarizing the above control example of the present invention, as shown in FIG. 6 (b), the transfer robot 202 (1) operates the ITM 224 to transfer the unpolished substrate to the position C accessible to the ITM 224. This is performed before the film thickness measurement for the previous substrate is completed. For this reason, after the ITM 224 finishes measuring the film thickness of the previous substrate and before starting the next film thickness measurement of the substrate, the transfer robot 202 (2) does not measure the film thickness at ITM 224 at the position C. Two operations are performed: handing over the substrate and (3) picking up the substrate from the ITM 224 at position C. That is, compared with the conventional control example shown in FIG. 6A, the throughput can be improved by the operation of (1).

  In this example, the ITM 224 controls the advance end warning signal by designating the number of remaining measurement points with respect to the total number of measurement points (total number of measurement points) for measuring the film thickness of the substrate loaded into the ITM 224. The timing to output to the unit 400 is determined. For example, when 10 measurement points are set for one substrate carried into the ITM 224 and the total number of measurement points is 10, the number of remaining measurement points is designated as 5. In this case, the film thickness of the substrate is measured at the five measurement points of the substrate into which the ITM 224 is loaded, and when the number of unmeasured points that have not yet been measured reaches 5, that is, the film at the fifth measurement point. When the thickness measurement is completed, the ITM 224 outputs a prior termination notice signal and inputs it to the control unit 400.

  Here, when the number of remaining measurement points is designated as 5 for a substrate in which the total number of film thickness measurement points on one substrate is set to 10, advance notice is given 5 seconds before the end of film thickness measurement from ITM 224. It is assumed that a signal is output and input to the control unit 400, and the transfer robot 202 starts a substrate transfer operation. In this case, if the tact time is an average of 170.5 seconds as an actual measurement value for two substrates, the transfer time of 5 seconds is equivalent to four times (measurement of film thickness of two unpolished substrates and two polished substrates) Measurement of the film thickness) is shortened.

Therefore, the throughput of the polishing apparatus in this case is
{3600 / (170.5-5 × 4)} × 2 = 47.8 (sheets / h)
It becomes.

On the other hand, in the conventional control example, that is, when the film thickness measurement end signal is output from the ITM 224 and is input to the control unit 400, and the transfer robot 202 starts the substrate transfer operation. Assuming that the tact time is an average of 170.5 seconds as measured values for two substrates, the throughput of the polishing apparatus in this case is
{3600 / 170.5} × 2 = 42.2 (sheets / h)
It becomes.

  In this way, for example, the advance end warning signal is output from the ITM 224, for example, 5 seconds before the end of the film thickness measurement, and is input to the control unit 400 so that the transfer robot 202 starts the substrate transfer operation. The throughput of the apparatus can be improved by 5.6 (= 47.8-42.2) (sheets / h).

  In this example, when the number of unmeasured measurement points reaches the number of measurement points specified in advance, the advance end notice signal is output from the ITM 224, so that the timing for outputting the advance end notice signal from the ITM 224 is arbitrarily set. Can be specified. Accordingly, it is possible to flexibly cope with the fluctuation of the film thickness measurement time according to the ITM 224 depending on the film thickness measurement condition (recipe), and to output the advance end warning signal from the ITM 224 at the optimum timing under the film thickness measurement condition. it can.

  In addition, the timing at which the ITM 224 outputs the advance end warning signal may be arbitrarily changed, so that optimum throughput can be obtained even when the substrate transfer method is changed. That is, if the polishing time or cleaning time of the substrate is changed on the polishing apparatus side after the timing at which the ITM 224 outputs the pre-end notice signal is changed, the movement of the transfer robot 202 changes, so the ITM 224 sends the pre-end notice signal. The output timing is not optimal.

  That is, if this timing is too early, a waiting time α until the film thickness measurement is completed in the ITM 224 occurs as shown in FIG. 7, and if the timing is too late, it is shown in FIG. This is the same as the “conventional control method”. For this reason, if the timing at which the ITM 224 outputs the advance end notice signal can be arbitrarily changed, it is possible to flexibly cope with a change in the transport method.

  Hereinafter, a method for determining the timing at which the ITM 224 outputs the advance end warning signal by monitoring the operation time of each unit with the polishing apparatus will be described.

As shown in FIG. 8, the film thickness measurement time required for the ITM 224 to actually measure the film thickness of the substrate is T _i1 , T _i2 ..., And the transfer robot 202 actually receives the film thickness measurement end signal or advance end notice signal from the ITM 224. T _R1 , T _R2, and so on are the robot transfer times from receiving the substrate to the ITM 224.

First, when the timing at which the ITM 224 first outputs the advance end warning signal is determined, the average thickness measurement time T is measured after the film thickness measurement is performed on n substrates without outputting the advance end warning signal from the ITM 224. _{i (AVE)} and average robot transfer time TR _(AVE) are obtained by the following formula.
T _{i (AVE)} = (T _i1 + T _i2 +... T _in ) / n
T _{R (AVE)} = (T _R1 + T _R2 +... T _Rn ) / n

Then, _T case _i in _{(AVE)> T R (AVE} ) is the _{[T i (AVE) -TR (AVE} ) ] seconds after after starting thickness measurements of the substrate ITM224, ITM224 pre termination notifying signal Is output. On the other hand, if T _{i (AVE)} ≦ TR _(AVE) , the ITM 224 outputs a prior termination notice signal at the same time as the ITM 224 starts measuring the film thickness of the substrate.

  As described above, the ITM 224 continues to monitor the film thickness measurement time and the robot transport time after determining the timing at which the advance end warning signal is first output, and every time the film thickness measurement for the n substrates is completed. The average value of the film thickness measurement time and the robot transport time is obtained, and the timing at which the optimum ITM 224 at that time outputs the advance end warning signal is determined. The n value is arbitrarily determined by the host computer 402 of the polishing apparatus, and the ITM 224 continues to output a prior termination notice signal every time film thickness measurement on n substrates is completed.

As a result, the timing at which the ITM 224 outputs the advance end notice signal can be arbitrarily changed.
Each time film thickness measurement for n substrates is completed, in addition to continuing to output a prior termination notice signal from ITM 224, every time film thickness measurement for one substrate is completed, for n substrates before An average value of the film thickness measurement time and the robot measurement time may be obtained, and an advance end warning signal may be output from the ITM 224.

  For example, the ITM film thickness measurement time is determined by the type of process such as Cu process or W process. Usually, when a substrate such as a semiconductor wafer is polished, there is almost no case where each substrate to be processed is a different process, and a certain number of substrates such as lot units are polished continuously in the same process.

  Therefore, as described above, it is possible to know whether or not the process has changed by monitoring the film thickness measurement time of the substrate processed earlier, and from ITM in advance according to the change in the film thickness measurement time. The timing for outputting the end notice output can be automatically adjusted.

  In particular, by updating every n substrates, it is possible to optimally narrow down the timing of outputting the preliminary end notice output from the ITM, and, for example, the recipe has been changed, and the polishing time, cleaning time, etc. have changed. Even in this case, the timing for outputting the preliminary end notice output from the ITM can be optimally reset.

  As described above, the waiting time of the ITM 224 and the transfer robot 202 can be reduced, and the overall throughput of the substrate transfer can be improved.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Top ring 100,216 Polishing table 101 Polishing pad 200 Running rail 202,208 Transfer robot 203a-203d Load port 204 Cassette 206 Mounting stand 210 Rotary transporters 212a, 212b 2nd washing machine 214a, 214b 1st washing machine 224 ITM (Thickness measuring device)
400 Control unit 402 Host computer

Claims (5)

In the substrate transfer method of transferring a substrate with a transfer robot while delivering the substrate to and from a film thickness measuring device that measures the thickness of the substrate,
The film thickness measuring device actually measures the film thickness with the film thickness measuring device for the substrate carried in from the total number of measurement points for measuring the film thickness with the film thickness measuring device for one substrate. When the number of unmeasured measurement points after subtracting the number of measured points has reached the number of measurement points specified in advance , a preliminary end warning signal is output,
Substrate transfer method characterized by receiving said pre-termination warning signal output from the film thickness measuring device for controlling the conveying robot to start the substrate transport operation.   The film thickness measuring device is obtained by monitoring, based on the film thickness measuring time for the previously processed substrate and the robot transport time required for the transport robot to transport the substrate to the film thickness measuring device, The substrate transfer method according to claim 1, wherein the advance completion notice signal is output. The film thickness measurement is performed on a predetermined number of substrates, and the average film thickness measurement time is obtained by dividing the film thickness measurement time of the predetermined number of substrates by the number of substrates.
Dividing the robot transfer time when the predetermined number of substrates are transferred to the film thickness measuring instrument by the transfer robot by the number of the substrates to obtain an average robot transfer time;
When the average film thickness measurement time is longer than the average robot transport time, the average robot transport time is subtracted from the average film thickness measurement time, and the time obtained by the subtraction after starting the film thickness measurement When the time has passed, the advance end warning signal is output,
3. The substrate transfer according to claim 1, wherein when the average film thickness measurement time is equal to or less than the average robot transfer time, the advance completion warning signal is output simultaneously with the start of the film thickness measurement. Method. Each time the film thickness measurement for the predetermined number of substrates is completed, an average value of the film thickness measurement time and the robot transfer time is obtained.
4. The substrate transfer method according to claim 3, wherein the timing at which the film thickness measuring device outputs the advance end warning signal is determined based on the average value. Every time the film thickness measurement for one substrate is completed, the average value of the film thickness measurement time and the robot measurement time for the predetermined number of substrates is obtained,
4. The substrate transfer method according to claim 3, wherein the timing at which the film thickness measuring device outputs the advance end warning signal is determined based on the average value.

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