JP2015210112A - Diagnostic device of linear motion mechanism, lubricant agent supply device, diagnostic method of linear motion mechanism and lubricant agent supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that enables abnormality to be highly accurately diagnosed in a device diagnosing a moving linear motion mechanism with a movement body being guided by a linear shank.SOLUTION: A device diagnosing a linear motion mechanism is configured to comprise: an AE wave detection unit that detects an AE wave at least at acceleration or deceleration of a movement body; and a diagnosis unit that diagnoses abnormality of an acceleration or deceleration area in a shank on the basis of a detection result by the AE wave detection unit. When a fall in lubricity of a lubricant agent and the like induce occurrence of the abnormality, the AE wave at the acceleration or deceleration occurs to thereby perform a diagnosis based on the AE wave, which in turn accuracy of the diagnosis can be enhanced.

Description

  The present invention relates to a device for diagnosing a linear motion mechanism that moves while a moving body is guided by a linear shaft portion, a lubricant supply device for the linear motion mechanism, a diagnostic method for the linear motion mechanism, and a lubricant supply method.

  In a substrate processing apparatus for processing a substrate such as a semiconductor wafer (hereinafter referred to as “wafer”), for example, in order to transport the substrate, a straight shaft portion (linear motion shaft) and the surface of the linear motion shaft are aligned with the direct motion shaft. A linear motion mechanism including a moving body that linearly moves along the movement axis is provided. In order to move the moving body smoothly, there is a case where a greasing operation for applying grease as a lubricant to the surface of the linear motion shaft may be performed during maintenance of the substrate processing apparatus.

  By the way, the allowable range of the size and amount of foreign matter adhering to the wafer is gradually narrowed. Therefore, it has been studied to suppress the dust generation due to the grease, the scattering of the grease, and the amount of gas (outgas) released from the grease. As a result, excessive wiping is performed after the grease is applied. In some cases, the greasing operation may not be performed during the maintenance. However, in such a case, wear and damage of the linear motion shaft and the moving body proceed quickly, and the life of the linear motion mechanism may be shortened.

  Under such circumstances, there is a demand for a technique capable of accurately diagnosing an abnormality in the linear motion mechanism and supplying grease to the linear motion shaft at an appropriate timing so that the supply amount does not become excessive. . By the way, Patent Document 1 describes a technique for supplying grease to a ball screw based on an amplitude value of vibration detected by a vibration pickup. However, such a vibration pickup detects a disturbance such as a vibration of a motor constituting the linear motion mechanism, and this disturbance becomes a relatively large noise. Accordingly, even if a relatively small vibration is generated in the linear motion mechanism due to a decrease in the lubricity of the grease, a minute crack (micro crack) is generated in the movable body and the linear motion shaft. Will be confused by the above noise. That is, it is difficult to accurately diagnose an abnormality that occurs in the linear motion mechanism.

  Japanese Patent Application Laid-Open No. H10-228707 describes monitoring of wear and damage of a rolling bearing that supports an axle by acoustic emission. However, this Patent Document 2 does not describe monitoring the wear or breakage of the linear motion mechanism.

JP 2004-211761 A JP 2009-20090 A

  The present invention has been made under such circumstances, and an object of the present invention is to provide a technology capable of diagnosing abnormality with high accuracy in an apparatus for diagnosing a linear motion mechanism in which a moving body moves while being guided by a linear shaft portion. Is to provide.

The linear motion mechanism diagnostic apparatus of the present invention is a device for diagnosing a linear motion mechanism that moves while a moving body is guided by a linear shaft portion.
An AE wave detection unit for detecting an AE wave at least during acceleration or deceleration of the moving body;
And a diagnosis unit that diagnoses an abnormality in the acceleration or deceleration region of the moving body in the shaft portion based on a detection result by the AE wave detection unit.

  According to the present invention, an AE wave detection unit that detects an AE wave when the moving body is accelerated or decelerated, and a diagnosis unit that diagnoses an abnormality based on the detection result of the detection unit are provided. It has been confirmed by an experiment described later that an AE wave is output when the moving body is accelerated or decelerated. Since abnormality diagnosis is performed based on the detection result of the AE wave, the accuracy of the diagnosis can be increased.

It is a longitudinal cross-sectional side view of the heat processing apparatus which concerns on this invention. It is a cross-sectional top view of the wafer conveyance area | region of the said heat processing apparatus. It is a perspective view of the wafer transfer mechanism provided in the said wafer conveyance area | region and including a linear motion mechanism. It is a side view of the wafer transfer mechanism. It is a schematic block diagram of the AE wave detection part provided in the said wafer transfer mechanism. It is a vertical side view of a ball screw and a nut provided in the linear motion mechanism. It is a vertical side view of a ball screw and a nut provided in the linear motion mechanism. It is a block diagram of the control part which controls the said linear motion mechanism. It is explanatory drawing of the outline | summary of the signal processing by the said control part. It is a block diagram of the control part which controls the said linear motion mechanism. It is a flowchart of control of the said linear motion mechanism. It is a perspective view of another linear motion mechanism. It is a cross-sectional top view of the moving body which comprises the said other linear motion mechanism. It is a vertical side view of the moving body which comprises the said other linear motion mechanism. It is explanatory drawing which shows an example of the greasing mechanism to the said ball screw. It is explanatory drawing which shows an example of the greasing mechanism to another ball screw. It is a graph explaining operation | movement of the linear motion mechanism in an evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test.

  A heat treatment apparatus 1 to which the lubricant supply apparatus of the present invention is applied will be described with reference to FIG. 1 which is a schematic side view. The heat treatment apparatus 1 heat-processes a plurality of wafers W, which are semiconductor substrates, at once. The heat treatment apparatus 1 includes a housing 11. In the figure, reference numeral 12 denotes a partition wall that divides the interior of the housing 11 in the front-rear direction. The front side and the rear side in the housing 11 are configured as a carrier transfer area 21 and a wafer transfer area 22, respectively. In the carrier transfer region 21, for example, a carrier 2 called FOUP (front open unified pod) storing 25 wafers W is transferred, and a downflow of clean air is formed by a gas supply unit (not shown). In the wafer transfer region 22, the wafer W taken out from the carrier 2 is transferred.

  The heat treatment apparatus 1 includes a carrier carry-in / out section 13 for transferring the carrier 2 between a transfer mechanism outside the heat treatment apparatus 1 and the heat treatment apparatus 1. The carrier carry-in / out section 13 is provided with a carrier carry-in / out stage 14 on which the carrier 2 is placed. The carrier loading / unloading stage 14 can move the carrier 2 in the front-rear direction between a delivery position outside the housing 11 by the transport mechanism and the carrier transport region 21 inside the housing 11. In the figure, reference numeral 15 denotes an opening 15 provided in the housing 11 for moving the stage 14 as described above.

  The carrier loading / unloading stage 14 is connected to a linear motion mechanism 141. The linear motion mechanism 141 includes a ball screw 142, a motor 143 that rotates the ball screw 142 around its axis, a ball screw bearing 144, a moving body 145 that includes a nut that is screwed to the ball screw 142, and the moving body 145 is moved to the ball screw 142. A guide 146 for moving in the axial direction is provided. The carrier loading / unloading stage 14 is connected to the moving body 145 and can move as described above.

  The carrier transfer area 21 is provided with a stocker 16 formed in a shelf shape, a first carrier transfer mechanism 17, a second carrier transfer mechanism 18, and a wafer transfer stage 19. The stocker 16 has a role of waiting for the carrier 2 that has not delivered the wafer W and the carrier 2 that has already delivered the wafer W. The wafer transfer stage 19 is a stage on which the carrier 2 is placed in order to deliver the wafer W between the carrier 2 and the wafer transfer region 22. In the figure, reference numeral 23 denotes an actuator provided on the wafer transfer stage 19, which presses the carrier 2 placed on the wafer transfer stage 19 against the partition wall 12.

  The first carrier transport mechanism 17 delivers the carrier 2 between the stocker 16 and the carrier loading / unloading stage 14 that has entered the housing 11, and the second carrier transport mechanism 18 is a first carrier transport mechanism. The carrier 2 is transferred between the stage 17 and the wafer transfer stage 19. Each of the carrier transport mechanisms 17 and 18 includes the linear motion mechanism 141 described above, and is configured so that the holding portions 17A and 18A for holding the carrier 2 can be moved up and down by the linear motion mechanism 141.

  Hereinafter, description will be made with reference to FIG. 2 which is a cross-sectional plan view of the wafer transfer region 22. In the figure, reference numeral 24 denotes an opening which is provided on the partition wall 12 and serves as a transfer port for the wafer W, and is closed from the wafer transfer region 22 side by an open / close door 25 configured to be movable up and down. The opening / closing door 25 includes a holding mechanism 26 that attaches / detaches the lid of the carrier 2 and holds the removed lid. The inside of the carrier 2 from which the lid is removed while being pressed against the partition wall 12 communicates with the wafer transport region 22 through the opening 24 and is partitioned from the carrier transport region 21. In such a state where the inside of the carrier 2 is partitioned from the carrier transfer area 21, the wafer W is transferred between the carrier 2 and the wafer transfer area 22.

  In FIG. 1, reference numeral 31 denotes a partition plate that divides the wafer transfer region 22 vertically. Below the partition plate 31, a transfer boat mounting table 32 and a standby boat mounting table 33 for mounting two wafer boats 3 serving as wafer W holders are provided. The wafer boat 3 is configured to hold about 100 to 150 wafers W in a vertical direction in a shelf shape and move within the wafer transfer region 22. Further, a wafer transfer mechanism 4 is provided in the wafer transfer area 22, and the wafer W is transferred between the carrier 2 on the wafer transfer stage 19 and the wafer boat 3 on the transfer boat mounting table 32. To do. The configuration of the wafer transfer mechanism 4 will be described in detail later.

A processing unit 34 which is a vertical heat treatment furnace is provided above the partition plate 31. The processing unit 34 includes a processing container 36 that is a cylindrical body having an opening 35 at the lower end and a ceiling. In the figure, reference numeral 37 denotes a heater 37 for heating the inside of the processing container 36. A gas supply unit and an exhaust port (not shown) are provided in the processing container 36. The wafer W carried into the processing container 36 while being held by the wafer boat 3 is supplied with gas while being heated, and is subjected to various heat treatments such as film formation, oxidation or annealing. In this example, an ALD (Atomic Layer Deposition) process in which SiH ₂ Cl ₂ (dichlorosilane) gas and NH ₃ (ammonia) gas are alternately and repeatedly supplied is performed, and a SiN (silicon nitride) film is formed on the wafer W. Is done.

In the figure, reference numeral 38 denotes a boat raising / lowering mechanism that raises and lowers the wafer boat 3 to carry the wafer boat 3 into and out of the processing container 36. The boat elevating mechanism 38 includes the linear motion mechanism 141 and a cap 39 connected to the linear motion mechanism 141. The cap 39 supports the wafer boat 3 and moves up and down, and closes the opening 35 when the wafer boat 3 is loaded into the processing container 36. Reference numeral 61 in the figure denotes a shutter that is movable so as to close the opening 35 after the wafer boat 3 is unloaded from the processing container 36. In the figure, reference numeral 62 denotes a boat transfer mechanism for transferring the wafer boat 3 between the boat mounting tables 32 and 33 and the boat lifting mechanism 38. In the figure, 63 and 64 are fan filter units (FFU), and 65 is a gas suction part. While the heat treatment apparatus 1 is in operation, the FFUs 63 and 64 supply, for example, N ₂ gas, which is an inert gas, in the horizontal direction, and the gas supply unit 65 sucks and exhausts the N ₂ gas, so that the wafer transfer region 22 becomes Keep clean.

  Next, the wafer transfer mechanism 4 to which the lubricant supply device is applied will be described with reference to the perspective view of FIG. 3 and the side view of FIG. This lubricant supply device includes a diagnostic device for a linear motion mechanism. The wafer transfer mechanism 4 includes a lift 42 that can be vertically moved by a linear movement mechanism 41 described later, a swivel 43 that is provided on the lift 42 so as to be rotatable about a vertical axis, and the swivel 43 on the swivel 43. An advancing / retreating portion 44 provided to freely move the swivel base 43 and five plate-shaped forks 45 extending from the advancing / retreating portion 44 in the forward direction of the advancing / retreating portion 44 are provided. Wafers W are supported on the upper surface of each fork 45 and transferred.

  The linear motion mechanism 41 includes a ball screw 46, a motor 47, a bearing 48, a nut 49, and a linear motion guide 40. The ball screw 46, which is a linear shaft portion, that is, a linear motion shaft, extends in the vertical direction, and grease is applied to the surface thereof as a lubricant. The motor 47 is provided at the upper end of the ball screw 46, and the bearing 48 is provided at the lower end. The motor 47 rotates the ball screw 46 around the axis. The bearing 48 supports the ball screw 46.

  A nut 49 that is a moving body is screwed into the ball screw 46 and is moved up and down by the rotation of the ball screw 46 by the motor 47. That is, the nut 49 moves while being guided by the ball screw 46. The lifting platform 42 is connected to the nut 49 and moves up and down together with the nut 49. In FIG. 4, the solid line and the alternate long and short dash line indicate the upper limit position and the lower limit position at which the nut 49 and the lifting platform 42 can move with respect to the ball screw 46, respectively. In order for the fork 45 to deliver the wafer W to each stage of the wafer boat 3, the nut 49 defines a region L including the position indicated by the solid line and the alternate long and short dash line and the region between these positions of the ball screw 46. It moves in the axial direction, and during this movement, acceleration and deceleration are performed at each position in the region L. That is, the region L is an acceleration region and a deceleration region of the nut 49.

  The motor 47 will be further described. The motor 47 rotates the ball screw 46 based on a control signal output from the control unit 7 described later. The motor 47 transmits a signal corresponding to the amount of rotation of the ball screw 46 to the control unit 7. Since the position of the nut 49 in the ball screw 46 changes in accordance with the amount of rotation of the ball screw 46, the control unit 7 controls the ball screw of the nut 49 based on a signal (position signal) output from the motor 47. The position at 46 can be identified.

  An AE (acoustic emission) wave detection sensor 51 is provided on the upper surface of the nut 49. If the grease on the surface of the ball screw 46 deteriorates or scatters, the lubricity thereof decreases, and if the nut 49 is accelerated or decelerated as described above in the region where the lubricity is degraded, the ball screw 46 A large load is applied to 46 and the nut 49. As a result, micro cracks and / or minute deformations occur in the ball screw 46 and / or the nut 49, and the elastic energy stored in these parts is released as sound waves (AE waves). The AE wave detection sensor 51 is a sensor for detecting the AE wave, and outputs a signal corresponding to the detected AE wave to the control unit 7. The frequency of this AE wave is several tens of kHz to several MHz.

  FIG. 5 is a longitudinal side view showing a schematic configuration of the AE wave detection sensor 51 which is an AE wave detection unit. In the figure, 501 is a bottom plate, 502 is a piezoelectric element provided on the bottom plate, 503 is a case covering the piezoelectric element 502, 504 is a signal cable connected to the case 503 from the outside, 505 is a connection between the piezoelectric element 502 and the cable 504. Wiring. The AE wave propagates from the ball screw 46 and the nut 49 to the piezoelectric element 502 through the bottom plate 501, and the piezoelectric element 502 is deformed to output an electric signal. This electric signal is output to the control unit 7 through the signal cable 504. In each figure other than FIG. 5, the signal cable 504 is not shown.

  The elevator 42 is provided with a grease pump 52 as a lubricant supply unit. Grease 50 as a lubricant is stored inside the grease pump 52, and the grease 50 is discharged into a flow path 53 provided in the nut 49 in accordance with a control signal (greasing signal) output from the control unit 7. To do. Referring to FIG. 6, which is a longitudinal side view of the nut 49, the downstream side of the flow path 53 opens to a gap between the outer periphery of the ball screw 46 and the inner periphery of the nut 49. The grease 50 discharged from the grease pump 52 is supplied to this gap by the discharge pressure. FIG. 7 shows a state in which the grease 50 is supplied as such. At the upper and lower ends of the inner periphery of the nut 49, weirs 54 and 54 are provided to prevent the grease 50 from spreading upward and downward of the nut 49, respectively. The weirs 54 and 54 are provided so as to surround the ball screw 46 close to each other. That is, the range in which the grease 50 is supplied on the surface of the ball screw 46 is limited between the weirs 54 and 54. That is, the grease 50 is locally supplied on the surface of the ball screw 46.

  In addition, each of the above-mentioned linear motion mechanisms 141 is different from the linear motion mechanism 41 in the member connected to the nut, as described above, there is something that moves the member connected to the nut in the horizontal direction, and Except that the AE wave detection sensor 51 and the grease pump 52 are not provided, the configuration is the same as the linear motion mechanism 41 described above.

  Next, the control unit 7 will be described. The control unit 7 is composed of, for example, a computer and includes a data processing unit composed of a program, a memory, and a CPU. The control unit 7 sends a control signal to each unit of the heat treatment apparatus 1 to the program, and the wafer W by the apparatus 1 Instructions (each step) are incorporated so as to advance the transfer and the processing of the wafer W. Specifically, gas supply / disconnection in the processing unit 34, power supplied to the heater 37, transfer of the wafer boat 3 by the boat transfer mechanism 62, transfer of the wafer W by the transfer mechanism 4, the stage 14 and the carrier transfer mechanism The operations such as the conveyance of the carrier 2 by 17 and 18 and the supply of the grease are controlled by the program. The program is stored in a storage unit such as a computer storage medium such as a flexible disk, a compact disk, a hard disk, or an MO (magneto-optical disk) and installed in the control unit 7.

  The controller 7 will be described in more detail with reference to the block diagram of FIG. In FIG. 8, for convenience of illustration, the position of the AE wave detection sensor 51 on the nut 49 is changed from the positions shown in other drawings. The control unit 7 includes a signal reception unit 71, a position information acquisition unit 72, an occurrence frequency calculation unit 73, a time detection unit 74, a signal processing unit 75, and a comparison unit 76. The position information acquisition unit 72, the occurrence frequency calculation unit 73, the signal processing unit 75, and the comparison unit 76 are configured by, for example, the above-described program, and the time detection unit 74 and the signal reception unit 71 are configured by, for example, hardware.

  The signal receiving unit 71 receives an output signal (AE wave detection signal) from the AE wave detection sensor 51. The signal receiving unit 71 transmits the AE wave detection signal to the signal processing unit 75, transmits a position acquisition command to the position information acquisition unit 72, and transmits an occurrence frequency calculation command to the occurrence frequency calculation unit 73. When receiving the position acquisition command, the position information acquisition unit 72 acquires a position signal (position information) of the nut 49 output from the motor 47 and stores the acquired position signal in a memory (not shown). The time detection unit 74 outputs data about the current time to the occurrence frequency calculation unit 73. When the occurrence frequency calculation unit 73 receives the calculation command, the occurrence frequency calculation unit 73 stores the time when the calculation command is received in a memory (not shown), and receives the calculation command received within a predetermined time (unit time) retroactive to the current time. (= Number of times the AE wave is generated), that is, the frequency of occurrence of the AE wave. The calculated occurrence frequency is output to the comparison unit 76.

  The signal processor 75 receives the AE wave detection signal from the signal receiver 71 and performs predetermined signal processing. An example of this signal processing will be described with reference to the schematic diagram of FIG. The upper graph in FIG. 9 shows an example of the waveform of the AE wave detection signal input to the signal processing unit 75. In the upper graph, the horizontal axis indicates time, and the vertical axis indicates energy intensity. The signal processing unit 75 performs a Fourier transform on the AE wave detection signal. The middle part of FIG. 9 shows an example of a signal waveform graph subjected to Fourier transform. In the middle graph, the horizontal axis represents frequency, and the vertical axis represents energy. Then, as shown in the lower part of FIG. 9, the signal processing unit 75 acquires the energy and frequency of the peak of the waveform peak in the graph obtained by performing the Fourier transform. When a plurality of peaks of the waveform appear, the energy and frequency at the peak of each peak are acquired. The signal processing unit 75 outputs the data regarding the energy and frequency acquired in this way to the comparison unit 76.

  Referring back to FIG. 8, the comparison unit 76 sets each reference value set in advance for the energy, frequency, and generation frequency of the AE wave, and the AE wave output from the signal processing unit 75 and the generation frequency calculation unit 73. Each value of energy, frequency, and AE wave occurrence frequency is compared. In FIG. 8, the flow of signals in each part from the generation of the AE wave during the raising and lowering of the nut 49 until the comparison is performed is indicated by arrows.

  When the position signal acquired as described above coincides with the position signal output from the motor 47 when the greasing operation mode described later is executed, that is, when the nut 49 is AE wave. A control signal (greasing signal) is output to the grease pump 52 when it is located at the position where the oil is generated. As a result, grease is supplied (greased) to this AE occurrence position. FIG. 10 shows the flow of signals when performing the greasing operation in this way by arrows. The greasing operation will be described in more detail later. In FIG. 10, for convenience of illustration, the position of the grease pump 52 on the lift 42 is shown at a position different from the other figures.

  The program of the control unit 7 controls the operation of the wafer transfer mechanism 4 by switching and executing two control modes set for the wafer transfer mechanism 4 based on the comparison result of the comparison unit 76. One of the control modes is a normal operation mode, and the wafer W is transferred between the carrier 2 on the wafer transfer stage 19 and the wafer boat 3 mounted on the transfer boat mounting table 32. This is a mode in which the above-mentioned lubrication is not performed. Another one of the operation modes is a greasing operation mode in which the above-described greasing is performed while the wafer W is being transferred. That is, the comparison unit 76 has a role of a diagnosis unit that diagnoses whether or not an abnormality has occurred in the ball screw 46. Further, according to the comparison result of the comparison unit 76, the grease is supplied to the generation position of the AE wave of the ball screw 46. Therefore, it can be said that the comparison unit 76 determines the position where the abnormality occurs in the ball screw 46. Note that the comparison with the reference value for the frequency by the comparison unit 76 determines the range of the frequency having a relatively high energy, so that the abnormality of the frequency is abnormal. The diagnosis can be said to be an abnormality diagnosis based on the frequency spectrum.

  The carrier 2 and wafer W transfer paths in the heat treatment apparatus 1 will be described. The carrier 2 is carried into the carrier carry-in / out stage 14 from the outside of the heat treatment apparatus 1 and is carried in the order of the first carrier transfer mechanism 17 → stocker 16 → second carrier transfer mechanism 18 → wafer transfer stage 19. . Then, the lid of the carrier 2 is removed by the opening / closing door 25, the opening / closing door 25 is opened, and the inside of the carrier 2 communicates with the wafer transfer region 22.

  By moving the fork 45 of the wafer transfer mechanism 4 up and down, rotating and advancing and retracting, the wafers W are sequentially carried out from the carrier 2 and moved from the upper side to the lower side of the wafer boat 3 mounted on the transfer boat mounting table 32. Then, the wafers W are sequentially loaded. When all the wafers W in the carrier 2 on the wafer transfer stage 19 are transferred to the wafer boat 3 and the carrier 2 becomes empty, the opening / closing door 25 is temporarily closed, and the carrier 2 is transferred to the stocker 16. . Then, the subsequent carrier 2 is transported from the stocker 16 to the wafer transfer stage 19, and the opening / closing door 25 is opened again. Similarly to the transfer of the wafer W of the preceding carrier 2, the wafer W of the subsequent carrier 2 is opened. Is transferred.

  When the predetermined number of wafers W have been mounted on the wafer boat 3, the open / close door 25 is closed, and the carrier 2 on the wafer transfer stage 19 is moved to the stocker 16. The wafer boat 3 is transferred from the transfer boat mounting table 32 to the boat lifting / lowering mechanism 38 and carried into the processing unit 34. Then, in a state where the wafer W is heated, each gas is supplied to the wafer W to form a SiN film.

  After this heat treatment, the wafer boat 3 is transported in the order of the boat lifting mechanism 38 → the standby boat mounting table 33 → the transfer boat mounting table 32. Then, the wafers W at each stage of the wafer boat 3 are sequentially transferred to the carrier 2 by the raising / lowering, rotation and advance / retreat operation of the fork 45 of the wafer transfer mechanism 4. The carrier 2 on which the wafer W is transferred is unloaded from the apparatus 1 through a path opposite to that when the wafer W is loaded into the heat treatment apparatus 1.

  The operation of the wafer transfer mechanism 4 when the wafer W is transferred as described above will be further described with reference to the flowchart of FIG. It is assumed that the normal operation mode is set and the wafer W is transferred between the carrier 2 and the wafer boat 3 as described above (step S1). During this transfer, the nut 49 moves the ball screw 46 in the axial direction and is accelerated or decelerated during this movement. At this time, if the lubricity of the grease in the region where the nut 49 is located on the surface of the ball screw 46 is reduced, the ball screw 46 and / or the nut 49 may be slightly deformed or micro cracks may be generated.

  The AE wave is emitted due to the occurrence of the deformation or the crack, and this AE wave propagates to the AE wave detection sensor 51 on the nut 49, and the AE wave is detected from the AE wave detection sensor 51 to the control unit 7 as described in FIG. A signal is transmitted. When the AE wave detection signal is received, the control unit 7 acquires the position signal transmitted from the motor 47 and calculates the occurrence frequency of the AE wave per unit time. Further, as described in FIG. 9, the energy and frequency of the peak apex are acquired for the waveform of the AE wave.

  The control unit 7 compares the acquired occurrence frequency, energy, and frequency with respective reference values (step S2). If any one of the generation frequency, energy, and frequency is lower than the reference value, the normal operation mode is continued. If, for example, all of the generation frequency, energy, and frequency are equal to or higher than the reference value, the normal operation mode is stopped and the operation proceeds to the greasing operation mode (step S3). Thus, even if the mode is changed, the transfer of the wafer W is continuously performed.

  During this transfer, when the nut 49 moves to the position where the ball screw 46 generates the AE wave, a control signal is output to the motor 47 so that the nut 49 stops. As described with reference to FIG. 10, the nut 49 is stopped based on the acquired position signal. In this manner, with the nut 49 stationary and the transfer operation of the wafer W temporarily stopped, a grease supply signal is transmitted to the grease pump 52, and a predetermined amount of grease is discharged from the grease pump 52. As a result, as described with reference to FIG. 7, grease is locally distributed to the position where the AE wave is generated in the ball screw 46 and is lubricated (step S <b> 4).

  After a predetermined time has elapsed since the grease was discharged, the transfer of the wafer W is resumed. Then, for example, when the nut 49 next moves to the generation position of the AE wave, a control signal is output so as to stop at the generation position, that is, decelerate at the generation position. When the AE wave detection signal is received at the time of deceleration and stationary, the generation frequency, energy, and frequency are compared with the respective reference values as in step S2. If all of the occurrence frequency, energy, and frequency are equal to or higher than the reference value, the greasing operation mode is continued, and the operation in step S4 is repeated. That is, grease is applied to the nut 49 that is stationary at the position where the AE wave is generated.

  When the nut 49 moves to the AE wave generation position, decelerates and stops, the AE wave detection signal is not received, and even if the AE wave occurs, the generation frequency, energy, and frequency are compared with the respective reference values. As a result, if any of them is lower than the reference value, the greasing operation mode is canceled and the normal operation mode is resumed.

  According to this heat treatment apparatus 1, an AE wave generated when the nut 49 is accelerated and decelerated when the nut 49 moves in the axial direction of the ball screw 46 in the wafer transfer mechanism 4 is detected. An AE wave detection sensor 51 is provided, and based on the detection result of the AE wave, the controller 7 diagnoses whether or not an abnormality has occurred, that is, whether or not the lubricity of the grease is reduced. As shown in an evaluation test described later, it is confirmed that an AE wave is generated when the lubricity of the grease on the surface of the ball screw 46 is lowered when the acceleration and deceleration are performed. Therefore, the presence or absence of the abnormality can be diagnosed with high accuracy. Further, when it is determined that an abnormality has occurred, the nut 49 moves to the AE wave generation position (abnormality generation position) in the ball screw 46 based on the stored position signal, and the grease pump 52 Since grease is locally applied to the AE wave generation position, it is possible to prevent excessive supply of grease to the surface of the ball screw 46. Accordingly, it is possible to suppress the grease supplied to the ball screw 46 from being scattered and adhering to the wafer W by the operation of the wafer transfer mechanism 4 and the gas released from the grease from adhering to the wafer W. As a result, the yield of semiconductor products manufactured from the wafer W can be suppressed.

  Since the AE wave detection sensor 51 may be provided at a position where the AE wave can be detected, the AE wave detection sensor 51 may be provided on the surface of the motor 47 or the bearing 48. However, the AE wave detection sensor 51 may be provided at a position close to the AE wave generation source. It is effective to provide the nut 49 as described above from the viewpoint of increasing the detection sensitivity. Further, even if a member that moves with the nut 49 relative to the ball screw, for example, the lifting platform 42, is relatively close to the generation source, the detection sensitivity can be increased.

  In step S2, the greasing operation mode is performed when all of the generation frequency, energy, and peak frequency of the AE wave are equal to or higher than the reference value. The greasing operation mode may be started when only one is greater than or equal to the reference value. As for step S5 for determining whether or not to continue the greasing operation mode as described above, the greasing operation mode is continued when only one or only two are equal to or higher than the reference value. Also good. Moreover, as a timing which performs step S5, after performing the greasing operation | movement of step S4, it may be when the nut 49 moves to an AE wave generation position next like the above-mentioned example, or step S4 It may be when the nut 49 has moved to the AE wave generation position after a predetermined time has elapsed after execution.

  In the above example, the transfer of the wafer W is interrupted and the greasing operation is performed. However, the greasing operation is not limited to this timing. For example, it is assumed that step S2 is performed during transfer of the wafer W to one wafer boat 3, and all of the AE wave generation frequency, energy, and peak frequency are equal to or higher than the reference value. Even if it becomes such a comparison result, the switching to the greasing operation mode is suspended and the normal operation mode is continued.

  That is, the transfer of the wafer W is continued without stopping the nut 49 at the AE wave generation position until the transfer of the set number of wafers W to the one wafer boat 3 is completed. Then, when the set number of wafers W has been transferred to the one wafer boat 3, the greasing operation mode is started, and the nut 49 is moved to the AE wave generation position to perform the greasing operation. . After this greasing operation, transfer of the wafer W from the one wafer boat 3 to the carrier 2 and transfer of the wafer W to the other wafer boat 3 are started. In this case, since the greasing operation is performed using the time that the wafer transfer mechanism 4 waits without being transferred to the wafer boat 3, the throughput can be improved. However, according to the technique in which the transfer of the wafer W is interrupted and the greasing operation is performed as described above, damage to the wafer transfer mechanism 4 can be more reliably suppressed.

  Similarly, when step S2 is being performed while the wafer W is being transferred from the wafer boat 3 to the carrier 2, even if all of the AE wave generation frequency, energy, and peak frequency are greater than or equal to the reference value. The switching to the greasing operation mode may be suspended. In that case, the greasing operation is performed at the position where the AE wave is generated until the set number of wafers W are transferred to the carrier 2 and the wafer W is transferred to the next carrier 2. Also in this case, since the greasing operation is performed using the time that the wafer transfer mechanism 4 waits, the throughput can be improved.

  In the above example, the AE wave detection sensor 51 and the grease pump 52 are provided in the linear motion mechanism 41 of the wafer transfer mechanism 4. However, the AE wave detection sensor 51 and the grease pump 52 are provided in the linear motion mechanism 141 described above. It may be provided and lubricated.

  The abnormality diagnosis method is not limited to the above example. For example, when making a diagnosis based on a frequency spectrum, a waveform of a graph representing the relationship between energy and frequency as shown in the middle of FIG. 9 is stored in the memory of the control unit 7. The waveform of the graph obtained by the Fourier transform described above when the AE wave is generated is compared with the waveform of the graph in the memory, and if they match or approximately match, the greasing operation is performed assuming that there is an abnormality. You may be allowed to

  Further, abnormality diagnosis may be performed based on the occurrence frequency and / or energy of the specific frequency component for the specific frequency component. For example, when the frequency of the peak peak of the waveform obtained by signal processing as described above is, for example, 90 kHz or more, the control unit 7 is configured to store the generation time of the AE wave in a predetermined memory. To do. The control unit 7 calculates the number of occurrences of the AE wave of 90 kHz or more, that is, the occurrence frequency of the AE wave in a period that is a predetermined time later from the stored time every time the occurrence time is stored. . And if the calculation result is more than a reference value, you may make it perform a greasing operation | movement as what has abnormality. Further, the control unit 7 compares the energy of the frequency with the reference value only when the peak peak frequency is 90 kHz or higher, for example. You may make it perform a greasing operation | movement.

  The present invention can also be applied to a linear motion mechanism 41 that does not include the ball screw 46 and the nut 49. FIG. 12 is a perspective view of the linear motion mechanism 81. The linear motion mechanism 81 includes a linear guide 82 that is a linear motion axis, and a moving body 83 that moves on the surface of the linear guide 82 along the linear guide 82. 13 and 14 are a cross-sectional plan view and a longitudinal side view of the moving body 83, respectively. The moving body 83 is provided with a large number of balls 84 along a circulation path 85 through which the balls 84 circulate. A part of the circulation path 85 is formed to be open to the surface of the linear guide 82. When the moving body 83 moves, the ball 84 rolls on the wall surface of the circulation path 85 and the surface of the linear guide 82 and circulates in the circulation path 85.

  Returning to FIG. 12, 86 is a main driving pulley rotated by a motor 47, and 87 is a driven pulley. Reference numeral 88 denotes a ring-shaped belt, which is wound around these pulleys 86 and 87. The moving body 83 is locked to the belt 88. The belt 88 is rotated by the rotation of the motor 47, whereby the moving body 82 moves along the linear guide 82. Similar to the linear motion mechanism 41, the position of the moving body 83 on the linear guide 82 changes according to the rotation amount of the motor 47. That is, the control unit 7 can specify the position of the moving body 83 in the axial direction of the linear guide 82 based on the signal from the motor 47.

  The AE wave detection sensor 51 and the grease pump 52 are provided on the surface of the moving body 83. The grease pump 52 discharges grease to the flow path 89 formed in the moving body 83 shown in FIGS. The downstream side of the flow path 89 is connected to a location opened on the surface of the linear guide 82 in the circulation path 85. Therefore, it is possible to locally lubricate between the linear guide 82 and the ball 84 positioned on the surface of the linear guide 82 by appropriately setting the grease discharge amount. Such a linear motion mechanism 81 can be used in place of the linear motion mechanism 41 and the linear motion mechanism 141 described above.

  The lubricant supply unit is not limited to being provided on the nut. FIG. 15 shows another configuration example of the wafer transfer mechanism 4. In the example of FIG. 15, unlike the wafer transfer mechanism 4 described above, an AE wave detection sensor 51 is provided on the nut 49 (not shown), but a grease pump 52 is provided on the lifting platform 42. Not. As shown in the figure, a linear motion mechanism 141 is provided in the vicinity of the wafer transfer mechanism 4, and a spray body 91 is provided on the moving body 145 of the linear motion mechanism 141. The spray unit 91 is configured to be movable in parallel with the nut 49 of the wafer transfer mechanism 4. The spray unit 91 stores liquid oil, and is configured to spray the oil locally toward the ball screw 46. As described above, when the AE wave is detected while the nut 49 of the wafer transfer mechanism 4 is moved up and down and the greasing operation mode is started, the nut 49 stops at a position retracted from the AE wave generation position. And the spraying part 91 moves to the position which can spray locally to the said AE wave generation position, and sprays oil.

  Further, as shown in an evaluation test described later, in order to switch the moving direction when the nut 49 repeatedly moves back and forth through the ball screw 46, in the region where acceleration and deceleration in the axial direction of the nut 49 are performed, Lubricity tends to decrease. That is, AE waves are likely to occur at both ends of the linear movement region of the nut 49 and in the vicinity thereof. FIG. 16 shows the linear motion mechanism 141 described above and the carrier loading / unloading stage 14 connected to the linear motion mechanism 141. The moving body 145 including the nut 49 of the linear motion mechanism 141 is reciprocated every time, and the movement in the axial direction is switched at a position indicated by a one-dot chain line and a two-dot chain line in the drawing. That is, the positions indicated by these chain lines are both ends of the linear movement region. In the ball screw 46, regions where acceleration and deceleration of the moving body 145 (nut 49) are performed are indicated by L1 and L2. The regions L1 and L2 include a region where the moving body 145 indicated by each chain line is located.

  In the linear motion mechanism 141 shown in FIG. 16, two spraying portions 91 described in FIG. 15 are provided so that oil can be sprayed onto the regions L1 and L2. Each spray portion 91 is fixed to the ball screw 46, unlike the one described in FIG. For example, when an AE wave is detected by the AE wave detection sensor 51 provided on the moving body 145, oil is sprayed from one of the two spray units 91 based on the position signal acquired from the motor 143.

  However, when the linear motion mechanism 141 is configured as shown in FIG. 16, oil may be sprayed from both of these two spraying portions 91. That is, when the AE wave is detected regardless of the position signal of the motor 143 and it is determined that the greasing operation mode is executed as a result of comparison with the reference value by the comparison unit 76 described above, the two spray units Instead of selecting which one of 91 to spray, you may make it spray from both the two spraying parts 91. FIG. Further, when the embodiment of the wafer transfer mechanism 4 is applied to the carrier loading / unloading stage 14 and the grease pump 52 is provided on the moving body 145, it is determined to perform the greasing operation mode as such. Then, the moving body 145 moves to the areas L1 and L2, respectively, and grease is supplied. Even if it does in this way, compared with supplying grease and oil to the ball screw 46 whole, the supply amount can be suppressed and the fall of the lubricity with respect to the ball screw 46 of the nut 49 can be suppressed.

  In the above example, the position where the AE wave is generated is specified by the motor 47, but the configuration is not limited thereto. For example, a plurality of optical sensors are arranged along the moving direction of the lifting platform 42. The optical sensor irradiates light in the horizontal direction, and when this light is applied to the elevator 42, it is reflected, and the optical sensor detects this reflected light. The position where the AE wave is generated may be specified by disposing each optical sensor so that different optical sensors can detect the reflected light depending on the position of the lift 42.

  Moreover, about greasing, it is not restricted to performing automatically. For example, in the above embodiment, the control unit 7 is provided with a monitor, and when an AE wave is detected, information about a position where the AE wave is generated is displayed based on a position signal from the motor 47. To. According to this position information, the user of the apparatus may manually supply grease. Further, when the moving body moves to a different position of the linear motion axis according to the time, the location at which the AE wave is generated on the linear motion axis is determined based on the time when the AE wave is detected, that is, the time information. You may identify and lubricate.

(Evaluation test)
Subsequently, an evaluation test performed in connection with the present invention will be described. This evaluation test was performed using a linear motion mechanism similar to the linear motion mechanism 41 described above, but the position where the AE wave detection sensor 51 was provided was the lift 42. Further, the lifting platform 42 is not provided with the swivel platform 43, the advance / retreat portion 44, and the fork 45. Instead, a weight is connected to the lifting platform 42. Before starting the test, grease was applied to the ball screw 46. And the raising / lowering stand 42 was raised / lowered repeatedly and the AE wave which generate | occur | produces at this time was acquired. No grease is supplied to the ball screw 46 while the elevator 42 is raised or lowered.

  The speed of the elevator 42 during the elevation was controlled so as to change periodically. The vertical axis of the graph in FIG. 17 is the ascending / descending speed, and the horizontal axis is the elapsed time. In the graph, symbols of times t1 to t9 are sequentially attached to one cycle. Between time t1 and t2, between t2 and t3, between t3 and t4, between t4 and t5, between t5 and t6, between t6 and t7, between t7 and t8, and between t8 and t9, respectively. 42 seconds, 0.10 seconds, 1.00 seconds, 0.10 seconds, 0.42 seconds, 0.10 seconds, and 1.00 seconds. The speed between t2 and t3 is 30 m / min, and the speed between t6 and t7 is −30 m / min. The speed between t4 and t5 and the speed between t8 and t9 are 0 m / min. At this time, the lifting platform 42 is located at the upper limit position and the lower limit position where it can move.

  FIG. 18 shows the position of the lifting platform 42 on the ball screw 46 and the number of occurrences of AE waves per unit time at each position, that is, the cumulative (accumulated) occurrence frequency. The vertical axis of the graph indicates the cumulative occurrence frequency. The horizontal axis of the graph corresponds to the position of the lifting platform 42, and the movement range of the lifting platform 42 is shown below the shaft. The upper and lower positions of the ball screw 46 are indicated by a two-dot chain line and a one-dot chain line, respectively. In this figure, the elevator 42 is shown in a simplified manner. Further, in the graph of FIG. 18, as described with reference to FIG. 9, the above-described occurrence frequency is divided into two according to the peak peak frequency obtained by Fourier transform. Specifically, the frequency of the AE wave having a peak apex frequency of 50 kHz or more and the frequency of generating an AE wave having a peak apex frequency lower than 50 kHz are shown separately. The occurrence frequency of the AE wave having the frequency of 50 kHz or more is indicated by a large number of dots immediately below the graph line.

  Further, FIG. 19 is a graph showing the position of the lifting platform 42 on the ball screw 46 and the integrated value (unit: eu) of the energy of the AE wave at each position. In FIG. 19, the measurement results are shown in the same manner as the graph of FIG. 18 except that the vertical axis of the graph indicates the integrated value of the energy.

  As described in the embodiment, it can be seen from these graphs of FIGS. 18 and 19 that AE waves are generated at the upper limit position and the lower limit position of the lifting platform 42 and in the vicinity thereof. That is, an AE wave is generated in a region where acceleration and deceleration are performed, and almost no AE wave is generated in a region moving at a constant speed. Therefore, as shown in FIG. 16 above, even if the greasing is limited to both ends and the vicinity of the region where the movable body reciprocates on the linear motion shaft, the linear motion shaft and the movable body are worn or damaged. Can be suppressed.

  Furthermore, the results of the evaluation test will be described. The graph of FIG. 20 is a graph showing the correspondence between the elapsed time from the start of the above test and the number of occurrences (occurrence frequency) of AE waves per unit time. In the graph, the horizontal axis represents elapsed time (unit: second), and the vertical axis represents the number of occurrences. The graph of FIG. 21 is a graph showing the correspondence between the elapsed time and the energy of the AE wave. In the graph, the horizontal axis represents elapsed time (unit: seconds), and the vertical axis represents the energy (unit: e.u.). The energy is acquired by performing the signal processing described with reference to FIG.

As described above, since grease is not added to the ball screw 46 during the test, the lubricity of the grease on the surface of the ball screw 46 decreases as the elapsed time increases. 20 and 21, it can be seen that the generation frequency and energy of the AE wave generally increase as the elapsed time becomes longer. The occurrence frequency and energy decrease at several places such as when the elapsed time is around 3 × 10 ⁵ seconds are considered to be caused by the change in the viscosity of the grease due to the influence of the temperature in the laboratory. From these graphs, it can be seen that the generation frequency and energy of AE waves generally correspond to a decrease in grease lubricity. Therefore, the lubricity of the grease can be monitored based on the occurrence frequency and / or energy, and as described in the embodiment, when the occurrence frequency becomes high and / or when the energy is detected high. It is effective to lubricate the ball screw 46.

  Further, the results of the evaluation test will be described. The signal processing described above was performed on the detection signal of the AE wave acquired during the test, and the energy and frequency of the peak apex were acquired. And this acquired frequency was contained in the range of 20 kHz-110 kHz. This band of 20 kHz to 110 kHz was divided into five. 20 kHz to less than 35 kHz is band A, 35 kHz to less than 45 kHz is band B, 45 kHz to less than 58 kHz is band C, 58 kHz to less than 90 kHz is band D, and 90 kHz to 110 kHz is band E.

  The relationship between the elapsed time when the frequencies of the bands A to E appear and the energy is shown in the graphs of FIGS. 22 and 23 for each band. 22 and FIG. 23, the horizontal axis represents elapsed time (unit: second), and the vertical axis represents energy (unit: e.u.) acquired together with the frequency by the signal processing. The solid line, the alternate long and short dash line, and the dotted line in the graph of FIG. 22 indicate the measurement results for the bands A, B, and C, respectively. The dotted line and the solid line in FIG. 23 indicate the measurement results for the bands D and E, respectively.

  Supplementing the graphs of FIGS. 22 and 23, actual measurement results are obtained by attaching different plots to the corresponding portions in the graph for each band, and showing the correspondence between the band, the elapsed time, and the energy. ing. FIG. 24 shows the actual measurement results for band E. Regarding such plot groups, regarding plots generated at substantially the same elapsed time, plots having the highest energy are selected and connected by lines to the graphs of FIG. 22 and FIG.

As shown in the graphs of FIGS. 22 and 23, only the AE waves in the bands A to D having a relatively low frequency are generated when the elapsed time is around 0 second to 10 × 10 ⁴ seconds. No AE wave in band E is generated. When the elapsed time exceeds 10 × 10 ⁴ seconds, an AE wave in the band E is generated, and the generation frequency thereof gradually increases. Therefore, as described in the embodiment, it is understood that the lubricity of grease, that is, the diagnosis of abnormality can be performed based on the frequency at the peak apex. Further, it can be seen that an abnormality can be diagnosed based on this band E, that is, the frequency of occurrence of a specific frequency component. In addition, for the band E, the energy increases as the elapsed time increases. Therefore, as described in the embodiment, it is understood that an abnormality can be diagnosed based on the energy of a specific frequency component.

W Wafer 1 Heat treatment apparatus 4 Wafer transfer mechanism 41 Linear motion mechanism 42 Lifting table 46 Ball screw 47 Motor 49 Nut 51 AE wave detection sensor 52 Grease pump 7 Control unit

Claims (13)

In an apparatus for diagnosing a linear motion mechanism in which a moving body moves while being guided by a linear shaft portion,
An AE wave detection unit for detecting an AE wave at least during acceleration or deceleration of the moving body;
A diagnostic device for a linear motion mechanism, comprising: a diagnostic unit that diagnoses an abnormality in an acceleration or deceleration region of the moving body in the shaft unit based on a detection result by the AE wave detection unit.   The linear motion mechanism diagnosis apparatus according to claim 1, wherein the AE wave detection unit is provided in the moving body.   The diagnosis unit is configured to determine a position of an abnormality in the shaft unit based on information in which position information of the moving body is associated with an AE wave detection result. A diagnostic apparatus for a linear motion mechanism according to 1 or 2.   The diagnosis unit is configured to diagnose the abnormality based on at least one parameter value among a parameter value group including an AE wave occurrence frequency, an AE wave energy, and an AE wave frequency spectrum. The diagnostic device for a linear motion mechanism according to any one of claims 1 to 3.   The linear motion mechanism according to claim 4, wherein the parameter value group further includes at least one of an occurrence frequency of a specific frequency component of the AE wave and an energy of the specific frequency component of the AE wave. Diagnostic device.   The diagnostic apparatus for a linear motion mechanism according to any one of claims 1 to 5, wherein the straight shaft portion is a ball screw, and the moving body includes a nut screwed into the ball screw.   The linear motion mechanism diagnosis apparatus according to claim 6, wherein the AE wave detection unit is provided on a surface of the nut.   A linear motion mechanism diagnostic device according to any one of claims 3 to 7, and a lubricant supply unit that supplies a lubricant to an abnormal position based on a result of diagnosis by the diagnostic device. A lubricant supply device. In a method for diagnosing a linear motion mechanism in which a moving body moves while being guided by a linear shaft portion,
Detecting an AE wave at least during acceleration or deceleration of the moving body;
Diagnosing an abnormality in the acceleration or deceleration region of the moving body in the shaft portion based on the detection result by the AE wave detection unit;
A method for diagnosing a linear motion mechanism, comprising:   The diagnosis step includes a step of determining an abnormal position in the shaft portion based on information in which position information of the moving body is associated with a detection result of an AE wave. Method for diagnosing linear motion mechanism.   The step of diagnosing includes the step of diagnosing the abnormality based on at least one parameter value among a parameter value group consisting of an AE wave occurrence frequency, an AE wave energy, and an AE wave frequency spectrum. The method for diagnosing a linear motion mechanism according to claim 9 or 10.   12. The linear motion mechanism according to claim 11, wherein the parameter value group further includes at least one of an occurrence frequency of a specific frequency component of the AE wave and an energy of the specific frequency component of the AE wave. Diagnosis method. A diagnostic method for a linear motion mechanism according to any one of claims 10 to 12,
And a step of supplying a lubricant to an abnormal position based on a result diagnosed by the diagnosis method.

Images