JP5604885B2 - Apparatus for removing deposits on the periphery of a workpiece - Google Patents

Description

The present invention relates to a deposit removing device of the workpiece peripheral edge for removing substances attached to the peripheral portion of the specimen.

  In the process of manufacturing a semiconductor device, for example, an organic substance, an inorganic substance, or an adhering substance (polymer) adhering to a peripheral edge of a side surface or back surface of a semiconductor wafer (hereinafter referred to as a wafer) is heated using laser light. May be removed. For example, the laser light is irradiated onto the wafer from the tip of an optical fiber drawn from the outside of the processing container that stores the wafer. Then, in the processing container, for example, the wafer is rotated about the vertical axis, and the tip of the optical fiber is moved or swung in the horizontal direction, so that the laser beam is scanned from the side surface side to the back surface side of the wafer, for example. Thus, the aforementioned deposits are removed over the entire circumference of the wafer W. Such deposits vary in the deposition state of film thickness, constituent materials, etc., depending on the type of processing performed on the wafer, for example, depending on the deposition state, for example, the output of laser light and the number of rotations of the wafer And the like are individually adjusted for each wafer (each processing type processed).

  By the way, when the optical fiber is disconnected and the laser light leaks to the outside, there is a risk of damaging each member or device, so that the disconnection of the optical fiber is detected. Specifically, as shown in Patent Documents 1 and 2, there is a method in which a wire made of a metal such as silver is wound around the optical fiber along the length direction of the optical fiber and the wire is energized. Are known. In this method, when the optical fiber is disconnected and the laser beam leaks from the disconnected portion to the outside, the laser beam is heated to several hundred degrees C. or more, for example, about 1000.degree. Disconnection can be detected.

  However, depending on the shape of the fracture surface of the optical fiber, even if the optical fiber is disconnected, the laser light hardly leaks to the outside so that the disconnection cannot be detected. There is a risk of returning to the laser oscillator side while melting. Even if the optical fiber is not physically disconnected, the optical fiber may be melted while the laser light is reflected on the back surface of the wafer and returns to the laser oscillator side in the optical fiber, for example. Furthermore, since the output of the laser beam is adjusted according to the adhesion state of the deposit, even if the laser beam leaks from the optical fiber due to the disconnection of the optical fiber, if the output of the laser beam is small, for example, 100 In some cases, the wire rod is not melted without being heated only to about several tens of degrees Celsius.

  Patent Document 2 describes a technique that uses a low-melting-point solder instead of the above-described metal such as silver as a wire for detecting disconnection of an optical fiber, but such a low-melting-point solder is brittle, As described above, when the optical fiber is moved or when the optical fiber is mounted on the apparatus, the optical fiber may be broken. In addition, since the solder is brittle, it is difficult to install (process) the solder so as to be wound along the length direction of the optical fiber.

JP 2004-205664 A JP 56-17303 A

The present invention has been made in view of such circumstances, and its object is to provide a deposit removing device of the workpiece periphery can detect the disconnection of the optical fiber for transmitting a laser beam.

The deposit removing device for the peripheral edge of the object of the present invention is:
A processing container for storing an object to be processed;
A mounting table that is provided in the processing container and supports a central part on the back surface side of the processing object so that a peripheral surface of the back surface side of the processing object faces the floor surface of the processing container in a circumferential direction;
Provided to the laser oscillator provided outside of the processing container through the wall portion of the processing container extending inside of the processing vessel, deposits by irradiating a laser beam on the peripheral portion of the specimen An optical fiber that transmits laser light for removal ;
A protective tube which is provided so as to surround the optical fiber at a tip portion of the optical fiber in the processing container and a portion where the optical fiber penetrates the wall of the processing container, and suppresses bending of the optical fiber; ,
Holding the tip part of the optical fiber, and a holding part which is a part of an optical fiber moving part for changing at least one of an irradiation position and an irradiation angle of the laser beam;
Is wired along the length of the optical fiber, the breakage detection line is energized to detect disconnection of the optical fiber,
A thermal fuse that is provided in the disconnection detection line at a portion where the protective tube is arranged in the length direction of the optical fiber, and is opened by a temperature rise at the time of disconnection of the optical fiber;
A disconnection detection unit that detects an interruption of energization of the disconnection detection line ,
The tip of the optical fiber is located below the height level of the object to be processed placed on the mounting table .

  The holding unit is configured to be movable so as to irradiate the laser beam from the back surface side peripheral portion of the object to be processed placed on the mounting table toward the back surface side central portion,
  The mounting table may be configured to be rotatable around the vertical axis so that the laser light can scan the peripheral edge of the back surface of the object to be processed in the circumferential direction.
  An exhaust port for exhausting the inside of the processing vessel;
  A processing gas supply unit for supplying a processing gas toward the peripheral edge of the object to be processed placed on the mounting table;
  It may be provided separately from the exhaust port, and may include a suction port for locally exhausting the processing gas supplied from the processing gas supply path.

The present invention, along the length of the optical fiber for transmitting the laser beam, as well as wiring disconnection detection line is energized to detect disconnection of the optical fiber, the Atsushi Nobori at the time of disconnection of the optical fiber An open circuit thermal fuse is provided on the disconnection detection line . For this reason, when the temperature of the optical fiber rises, the energization is interrupted in the thermal fuse, so that the disconnection of the optical fiber can be detected.

It is a longitudinal section which shows the polymer removal apparatus which is an example of the laser irradiation apparatus provided with the laser irradiation apparatus of this invention. It is a top view which expands and shows a part of said polymer removal apparatus. It is the schematic which shows an example of the laser irradiation apparatus in the said polymer removal apparatus. It is a perspective view which shows the lens part in the said laser irradiation apparatus. It is sectional drawing which cut | disconnected the optical fiber of the said laser irradiation apparatus along the length direction. It is sectional drawing which cut | disconnected the optical fiber of the said laser irradiation apparatus along the circumferential direction. It is the schematic which shows the other example of the said laser irradiation apparatus. It is the schematic which shows the other example of the said laser irradiation apparatus.

As an example of an embodiment of a laser heating device including an optical fiber breakage detection device according to the present invention, deposits attached to, for example, a side edge surface or a back surface peripheral portion of a semiconductor wafer (hereinafter referred to as “wafer”) W which is an object to be processed. The polymer removal apparatus which removes (polymer) is demonstrated with reference to FIGS. First, the overall configuration of the laser heating apparatus will be briefly described.
The polymer removal apparatus includes a processing container 1 for storing a wafer W therein and performing a removal process of deposits, and is provided in the processing container 1 to support the central portion of the wafer W by suction from the back side. The spin chuck 2 which is a mounting table for rotating the wafer W around the vertical axis, and the wafer W on the spin chuck 2 is attached to the wafer W by irradiating laser light, for example, from the side end surface to the peripheral edge of the back surface. And a laser irradiation device 3 that heats and removes deposits. In FIG. 1, reference numeral 4 denotes a wafer W transfer opening that is airtightly opened and closed by a gate valve G, 5 is provided on the upper side of the processing container 1, and an intake device for taking an external atmosphere into the processing container 1. A filter unit for removing particles in the external atmosphere sucked by the intake device 5, and the exhaust device 9 connected to the exhaust pipe 8 extending from the exhaust port 7 on the bottom surface of the processing container 1 and the intake device 5, A down flow is formed in the processing container 1. Note that an opening 1 a for allowing an external atmosphere taken in by the intake device 5 to flow into the processing container 1 is formed at a position below the filter unit 6 on the ceiling surface of the processing container 1.

  The spin chuck 2 includes an elevating shaft 2b extending airtightly through the floor surface of the processing vessel 1 from a driving unit 2a provided below the processing vessel 1 toward the upper side. It is configured to be rotatable at a predetermined rotation number around the vertical axis. The spin chuck 2 is configured to be movable up and down so that the wafer W can be transferred to and from a transfer arm (not shown) that enters the processing chamber 1 through the transfer port 4. Further, a suction path (not shown) is provided in the elevating shaft 2b in order to suck and hold the wafer W from the back side. In FIG. 1, 2c is a bearing part and 2d is a bellows.

  In the processing container 1, a support portion (a central portion in the height direction is recessed in a rectangular shape so as to face the upper side, the side side, and the lower side of the peripheral portion of the wafer W attracted and held on the spin chuck 2. (Main body) 11 is provided. The supporting portion 11 includes a processing gas supply nozzle 12 for supplying a processing gas for removing deposits, for example, O3 gas, toward the side end surface and the peripheral portion on the back surface side of the wafer W, and the laser irradiation apparatus 3 described above. And a local exhaust pipe disposed so that an opening end (suction port) is close to the back side of the wafer W in order to suck and exhaust the processing gas discharged from the processing gas supply nozzle 12 toward the wafer W. 13 and a measurement unit 14 including, for example, a radiation thermometer for measuring the temperature of the wafer W at the portion irradiated with the laser light. The other end side of the local exhaust pipe 13 is connected to the exhaust pipe 8 described above. As shown in FIG. 1, a rail 11 a for moving a lens unit 23 (described later) in the horizontal direction in the radial direction of the wafer W is disposed on the side surface of the support unit 11.

As shown in FIG. 3, the laser irradiation device 3 includes a laser oscillator 21 that oscillates laser light with an output of, for example, 200 W or less outside the processing container 1, and one end side (base end side) connected to the laser oscillator 21. At the same time, the other end side (front end side) penetrates the wall surface of the processing vessel 1 in this example in an airtight manner and extends flexibly toward a position close to the back surface of the wafer W on the spin chuck 2, for example, quartz. And a lens unit 23 that is connected to the other end of the optical fiber 22 and collects the laser light transmitted from the laser oscillator 21 and irradiates the wafer W. The lens portion 23 is fixed to a base plate 25 which is a holding portion by a clamp member 24, and as shown in FIGS. 2 and 4, the support portion described above is provided by a moving portion 26 connected to the base plate 25. 11 is provided so as to be movable in the radial direction of the wafer W on the spin chuck 2 along a rail 11a provided in a horizontal direction on the spin chuck 2 and at a rotating shaft 26a provided between the base plate 25 and the moving part 26. The laser beam is supported in a swingable manner so that the irradiation angle of the laser beam with respect to W can be changed. In FIG. 2, the upper side of the support portion 11 is partly cut away.
The optical fiber 22 in a part close to the lens unit 23 is fixed to the base plate 25 by a fixing band 27.

  The optical fiber 22 is fixed to the floor surface of the processing container 1 by an L-shaped fiber fixing bracket 28 through a fiber fixing member (not shown). In order to suppress the bending of the optical fiber 22 between the lens unit 23 and the fixed band 27 and around the optical fiber 22 at a portion penetrating the bottom surface of the processing container 1, protective tubes 30 and 40 described later are provided. ing.

  Next, a specific configuration of the optical fiber 22 will be described. As shown in FIGS. 5 and 6, the optical fiber 22 is configured as a double tube of an inner tube (core) 22a and an outer tube (clad) 22b covering the inner tube 22a. In order to prevent the optical fiber 22 from being bent beyond the angle at which the optical fiber 22 is cut between the base end portions 31a and 31b provided on the lens portion 23 side, for example, a bellows-like sheath tube 32 made of stainless steel is provided as the optical fiber. The optical fiber 22 is disposed along the length direction so as to cover the outside of the optical fiber 22. A coating layer 33 made of, for example, a resin is provided on the outside of the sheath tube 32. The coating layer 33 is made of, for example, PVC (polyvinyl chloride) on the laser oscillator 21 side outside the processing container 1. In the processing container 1, the optical fiber 22 and the sheath tube 32 are made of silicone rubber or the like so that they can be bent easily. A protective material 34 made of PVC is provided between the sheath tube 32 and the coating layer 33 outside the processing container 1. Between the lens unit 23 and the fixed band 27 described above, the above-described protective tube 30 made of, for example, stainless steel for suppressing the bending of the optical fiber 22 is provided, and a portion penetrating the floor surface of the processing container 1. A similar protective tube 40 is also provided in the optical fiber 22 (coating layer 33).

  In the sheath tube 32 between the base end portions 31a and 31b, a net-like body 35 made of, for example, nylon is provided so as to cover the optical fiber 22 along the length direction. The covering member 36 covers the distal end portions on both sides in the length direction and the inner region of the protective tube 40. A conductive disconnection detection line 41 made of, for example, copper (Cu) is inserted into the mesh body 35 via the tube wall of the sheath tube 32 outside the processing container 1. The wires are spirally wired so as to be wound toward the tip along the fiber 22. Further, the disconnection detection line 41 is folded back at the distal end side of the optical fiber 22 and wired to the proximal end side along the optical fiber 22, and from the vicinity of the insertion site on one end side of the disconnection detection line 41, It is pulled out through the tube wall and connected to a monitoring unit 43 for detecting disconnection of the optical fiber 22. As shown in FIG. 5, the monitoring unit 43 includes a power source 43a for passing a current for detecting the disconnection of the optical fiber 22 through the disconnection detection line 41, and the disconnection detection line 41. And a detection unit 43b made of, for example, a relay that detects whether or not the current flowing through 41 is interrupted.

  Further, in the inner region of the portion where the protective tubes 30 and 40 are provided in the length direction of the optical fiber 22, for example, a temperature fuse (thermal fuse) 42 manufactured by Matsushita Electric Co., Ltd. is provided in series with the disconnection detection line 41. The temperature fuse 42 is used when the set temperature (melting temperature) for interrupting the current flowing through the temperature fuse 42 is lower than the melting temperature of the disconnection detection line 41 and is used when the optical fiber 22 is disconnected. The temperature is set so that the temperature of the optical fiber 22 rises according to the laser output, for example, 141 ° C. (141 ° C. ± 2 ° C.). FIG. 6 shows a cross section of the optical fiber 22 cut along line AA in FIG. Although not shown, the surface of the disconnection detection line 41 is covered with, for example, enamel.

  As shown in FIG. 1, the polymer removing apparatus includes a control unit 50 including, for example, a computer. The control unit 50 includes a data processing unit including a program, a memory, and a CPU. The program adjusts processing conditions such as the rotation speed of the spin chuck 2, the output of the laser oscillator 21, and the supply amount of O 3 gas, thereby removing deposits adhering to the peripheral portion on the side surface or the back surface of the wafer W. In this way, a control signal is sent to each part of the apparatus. In addition, in the memory, for example, the type of processing performed on the wafer W, the type of deposits (organic matter, inorganic matter, or a laminate thereof) attached to the wafer W according to the type of processing, and the film thickness And a processing condition for removing the deposits are provided. The processing conditions are read from the memory by the CPU, and the deposit removal process is performed by the program. This program (including programs related to processing parameter input operations and display) is stored in the storage unit 51 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 50. The The laser irradiation apparatus is configured by the optical fiber 22, the disconnection detection line 41, the thermal fuse 42, the control unit 50, and the like.

  Subsequently, the operation of the polymer removing apparatus will be described. First, the processing conditions are read from the recipe, and the wafer W is loaded into the processing container 1 from the transfer port 4 by a transfer arm (not shown) and placed on the spin chuck 2. For example, a deposit P made of an organic material is attached to the peripheral edge of the back surface of the wafer W, for example. The wafer W is sucked and held, and is rotated around the vertical axis at a predetermined rotational speed, for example, and a downflow is formed in the processing container 1 by the exhaust device 9 and the intake device 5. Further, O 3 gas is discharged toward the peripheral edge of the wafer W, and this O 3 gas is locally exhausted by the local exhaust pipe 13.

  Next, the disconnection detection line 41 is energized by the monitoring unit 43. Further, the laser oscillator 21 oscillates a semiconductor laser beam having a wavelength of, for example, 808 nm with an output of 200 W, for example, and irradiates the wafer W with the laser beam through the lens unit 23, whereby the wafer W is heated to a predetermined heating temperature, for example, 500 Heat to about ℃. Then, the temperature of the wafer W is measured by the measurement unit 14 to adjust the rotation speed of the wafer W and the output of the laser beam so that the wafer W is maintained at the temperature, and the lens unit 23 via the moving unit 26. Is moved or rocked, and the deposit P attached to the wafer W is removed by heating in the circumferential direction by irradiating a laser beam from the side surface side to the peripheral portion on the back surface side of the wafer W.

  At this time, the optical fiber 22 is bent between the protective tubes 30 and 40 on the lens unit 23 side and the laser oscillator 21 side by moving or swinging the lens unit 23. Then, it is assumed that the optical fiber 22 is disconnected in a region close to the lens unit 23 due to this bending, for example. In this case, laser light leaks from the optical fiber 22 into the processing container 1, for example, and the periphery of the broken portion is heated to, for example, about 1000 ° C. by the laser light. For example, when the optical fiber 22 is melted by this heat, for example, the laser light transmission region (inner tube 22a) in the optical fiber 22 is blocked, so that the laser light transmitted from the laser oscillator 21 can pass through the disconnected portion. Disappear. Therefore, the temperature of the optical fiber 22 further rises, and for example, the melted portion of the optical fiber 22 gradually spreads to the laser oscillator 21 side. Further, for example, the disconnection detection line 41 around the optical fiber 22 is also heated by the heat of the laser light leaking outside from the optical fiber 22, but when the output of the laser light is about 45 W as described above. The disconnection detection line 41 is heated only up to about 200 ° C., and therefore the disconnection detection line 41 is not melted.

  Thereafter, when the melting portion of the optical fiber 22 reaches the floor surface (thermal fuse 42) of the processing container 1, the melting temperature of the thermal fuse 42 is set as described above, so that the optical fiber 22 leaks out. The thermal fuse 42 is melted by the heat of the laser beam, and the current flowing through the disconnection detection line 41 is interrupted (opened). Then, the current interruption is detected by the monitoring unit 43, the detection signal is sent to the control unit 50, a stop signal is output from the control unit 50 to the laser oscillator 21, and the oscillation of the laser beam is instantaneously stopped. Will be. The time from when the optical fiber 22 is disconnected until the temperature fuse 42 is melted is, for example, about several seconds to several tens of seconds.

  According to the above-described embodiment, when the disconnection detection line 41 wired along the length direction of the optical fiber 22 that transmits the laser light is energized and the disconnection of the optical fiber 22 is detected by the interruption of the energization, Since the fuse 42 is provided in the disconnection detection line 41, even if the output of the laser light is low enough that the disconnection detection line 41 is not melted by the heat of the laser light leaking outside from the disconnection portion of the optical fiber 22, Since the current is interrupted in the thermal fuse 42, the disconnection of the optical fiber 22 can be reliably detected. Therefore, for example, damage to the laser oscillator 21 due to the laser light can be suppressed. In addition, when the protective tubes 30 and 40 that suppress the bending of the optical fiber 22 are arranged so as to surround the optical fiber 22, the thermal fuse 42 is attached to the same portion as the protective tubes 30 and 40 in the length direction of the optical fiber 22. By providing, it is possible to suppress breakage of the disconnection detection line 41 due to the handling of the optical fiber 22 (horizontal movement, swing or attachment of the optical fiber 22 to the apparatus).

  In addition, since the thermal fuse 42 is provided in the disconnection detection line 41 along the length direction of the optical fiber 22, the disconnection can be easily performed as compared with the case where a low melting point metal such as solder is provided instead of the disconnection detection line 41. A detection line 41 (temperature fuse 42) can be installed. Further, the melting temperature of the thermal fuse 42 is set strictly as described above, and since the individual difference of the melting temperature is small, that is, the current can be cut off at a preset temperature, the thermal fuse 42 is further changed. After melting and cutting off the current, it is not reconnected by refusion or the like, so that the disconnection of the optical fiber 22 can be accurately detected.

  In the above-described example, the case where the optical fiber 22 is disconnected and the laser light leaks to the outside has been described. For example, depending on the shape of the disconnected portion of the optical fiber 22, the laser light hardly leaks to the outside. While the optical fiber 22 is melted and the disconnection detection line 41 is not melted, the optical fiber 22 may return to the laser oscillator 21 side. Even in such a case, by using the temperature fuse 42, the optical fiber 22 22 disconnection can be reliably detected. Even if the optical fiber 22 is not broken, for example, since the surface of the wafer W is a mirror surface, the laser light is reflected by the wafer W and enters the optical fiber 22, and the optical fiber 22 is, for example, 1000 In some cases, the laser oscillator 21 may be returned to the laser oscillator 21 side while being heated to about ° C and melted. Also at this time, the temperature rise of the optical fiber 22 can be detected similarly. In this case, the current is interrupted by the temperature fuse 42 close to the lens unit 23. Therefore, the “disconnection” of the optical fiber 22 described in the present invention means that the laser light is reflected on the surface of the wafer W and reflected by the laser oscillator 21 in addition to the case where the optical fiber 22 is physically disconnected by repeated bending. The case where the optical fiber 22 melts at a midpoint by returning while melting the optical fiber 22 to the side is also included.

  In this example, the temperature fuses 42 are provided at two locations of the lens portion 23 and the through portion of the floor surface of the processing container 1, but may be provided at three or more locations. In that case, as shown in FIG. 7, for example, a protective tube 30 is provided at a bent portion of the optical fiber 22, and a thermal fuse 42 is provided inside the protective tube 30. Further, when the lens unit 23 is not moved or swayed in the horizontal direction, the thermal fuse 42 may be interposed in the disconnection detection line 41 without providing the protective tube 30.

  Further, as shown in FIG. 8, a thermocouple 61 for measuring the temperature of the optical fiber 22 is arranged in place of the thermal fuse 42, and the temperature of the optical fiber 22 is measured in the monitoring unit 43 which is a temperature detection unit. Anyway. In this example, the temperature measuring unit of the thermocouple 61 is arranged in the inner region of the protective tube 30 described above (the region close to the lens unit 23 and the through portion of the floor of the processing container 1). In this case, for example, when the temperature of the optical fiber 22 becomes equal to or higher than a predetermined temperature (threshold value) set in advance, it is determined that the optical fiber 22 is disconnected. When the thermocouple 61 is provided in this way, the threshold value is adjusted according to the output of the laser beam.

W Wafer 1 Processing vessel 2 Spin chuck 2a Drive unit 3 Laser irradiation device 21 Laser oscillator 22 Optical fiber 23 Lens unit 26 Moving unit 30 Protective tube 41 Disconnection detection line 42 Thermal fuse 43 Monitoring unit P Attachment

Claims (3)

A processing container for storing an object to be processed;
A mounting table that is provided in the processing container and supports a central part on the back surface side of the processing object so that a peripheral surface of the back surface side of the processing object faces the floor surface of the processing container in a circumferential direction;
Provided to the laser oscillator provided outside of the processing container through the wall portion of the processing container extending inside of the processing vessel, deposits by irradiating a laser beam on the peripheral portion of the specimen An optical fiber that transmits laser light for removal ;
A protective tube which is provided so as to surround the optical fiber at a tip portion of the optical fiber in the processing container and a portion where the optical fiber penetrates the wall of the processing container, and suppresses bending of the optical fiber; ,
Holding the tip part of the optical fiber, and a holding part which is a part of an optical fiber moving part for changing at least one of an irradiation position and an irradiation angle of the laser beam;
Is wired along the length of the optical fiber, the breakage detection line is energized to detect disconnection of the optical fiber,
A thermal fuse that is provided in the disconnection detection line at a portion where the protective tube is arranged in the length direction of the optical fiber, and is opened by a temperature rise at the time of disconnection of the optical fiber;
A disconnection detection unit that detects an interruption of energization of the disconnection detection line ,
The tip removal part of the optical fiber is located below the height level of the object to be processed placed on the mounting table .   The holding unit is configured to be movable so as to irradiate the laser beam from the back surface side peripheral portion of the object to be processed placed on the mounting table toward the back surface side central portion,
  2. The object according to claim 1, wherein the mounting table is configured to be rotatable about a vertical axis so that the laser beam can scan the peripheral edge of the back surface of the object to be processed in the circumferential direction. A deposit removing device for the periphery of the processing body.   An exhaust port for exhausting the inside of the processing vessel;
  A processing gas supply unit for supplying a processing gas toward the peripheral edge of the object to be processed placed on the mounting table;
  The to-be-processed object of Claim 1 or 2 provided with the suction port for providing separately from the said exhaust port and exhausting the process gas supplied from the said process gas supply path locally A device for removing extraneous matter from the periphery of the body.

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