JP2018067668A - Sheet expansion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet expansion device capable of reducing occurrence of undivided area and/or defective area of chip spacing expansion.SOLUTION: The sheet expansion device for expanding an expanding sheet in a workpiece unit in a state that a workpiece is supported by an annular frame F which have an opening in a central area via an expanding sheet T, includes: annular frame fixing means that fixes an annular frame, which has a supporting plane for supporting the annular frame of a workpiece unit; expanding means that expands the expanding sheet by pressing the expanding sheet positioned between the inner periphery of the annular frame and the outer periphery of the workpiece by means of a pressing part; a cassette placing table on which a cassette accommodating plural workpiece units is placed; transportation means 18 that transports a workpiece unit from the cassette so that the annular frame of the workpiece unit is placed on the supporting plane of the annular frame fixing means; and detection means that detects displacement in a horizontal direction with respect to the pressing part of the placed workpiece unit.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a sheet expanding apparatus that expands an expanded sheet to which a workpiece such as a wafer is attached.

  A wafer such as a semiconductor wafer formed in an area partitioned by a plurality of division lines in which a plurality of devices such as ICs and LSIs are formed in a lattice shape is formed into individual device chips by a dicing apparatus or a laser processing apparatus. The divided device chips are widely used in various electronic devices such as mobile phones and personal computers.

  In recent years, laser processing apparatuses that have been widely used irradiate a wafer with a laser beam having a wavelength that is transparent to the wafer, align the focal point inside the wafer, and irradiate it along the planned dividing line. After that, the expanded sheet on which the wafer is attached is expanded by a sheet expansion device to apply an external force to the wafer, and the wafer is broken along the modified layer to divide it into individual device chips. (For example, refer to Japanese Patent No. 3408805).

  After the modified layer is formed inside the wafer, the expanded sheet is expanded by the sheet expanding device to divide the wafer into individual device chips, and after the modified layer is formed inside the wafer, the back side of the wafer A sheet expanding apparatus is also used to extend the chip interval after a dividing method called SDBG (Stealth Ding Before Grinding) method in which grinding is performed to divide the wafer into individual device chips.

  Examples of the workpiece to be divided into individual chips by the sheet expanding device include DAF (Die Attach Film) attached to the back surface of the wafer. Japanese Patent Application Laid-Open No. 2009-272503 discloses a DAF dividing apparatus and dividing method that divides a DAF by expanding an expanded sheet.

Japanese Patent No. 3408805 JP 2009-272503 A JP 2010-206136 A

  In the sheet expanding device disclosed in Patent Document 3, if the position of the upper end of the cylindrical push-up member acting as a pressing portion and the annular frame constituting the wafer unit are shifted, the expanded sheet cannot be expanded evenly and is not divided into wafers An area may be generated or an area having a narrow chip interval may be generated.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a sheet expanding apparatus that can reduce the possibility of generating undivided areas and defective chip interval expansion defects. is there.

  According to the present invention, a division starting point is formed along a plurality of intersecting scheduled lines, or an opening is provided in the center via an expanded sheet attached to the back surface of a workpiece divided into individual chips. A workpiece unit in a form in which a workpiece is supported on an annular frame having a sheet expanding device for expanding the expanded sheet, the workpiece unit having a support surface for supporting the annular frame, An annular frame fixing means for fixing the annular frame placed on the support surface; and the expanded sheet between the inner periphery of the annular frame fixed by the annular frame fixing means and the outer periphery of the workpiece. An expanding means that expands the expanded sheet by being pressed by the pressing portion, a cassette mounting table on which a cassette capable of accommodating a plurality of workpiece units is placed, and a workpiece unit A conveying means for conveying the workpiece unit from the cassette placed on the cassette placing table, so that the annular frame is placed on the supporting surface of the annular frame fixing means; There is provided a sheet expanding device, comprising: a detecting unit that detects a horizontal displacement of the placed workpiece unit with respect to the pressing portion.

  Preferably, the seat expansion device further includes a warning transmission unit that issues a warning when the positional deviation detected by the detection unit exceeds an allowable range.

  Preferably, the sheet expanding apparatus further includes a control unit that controls at least the conveying unit, and the control unit is configured to prevent a positional deviation in a horizontal direction with respect to the pressing portion of the workpiece unit placed on the support surface. When the positional deviation detected by the detection means and the positional deviation detected by the detecting means is outside the allowable range stored in the allowable range storage, the annular frame of the workpiece unit is placed on the support surface. And a re-transport command unit that controls the transport means so as to be transported again.

  Preferably, the detection means includes an irradiation unit that irradiates light to the annular frame placed on the support surface, and a detection unit that detects one of transmission, reflection, and light shielding of the light irradiated from the irradiation unit. including.

  Since the seat expansion device of the present invention includes detection means for detecting a positional deviation of the annular frame placed on the support surface with respect to the pressing portion, the expansion is performed in a state where the annular frame is displaced with respect to the pressing portion. It can be prevented from being carried out. Therefore, it is possible to prevent the generation of undivided areas and the generation of chip interval expansion failure areas.

It is a perspective view of the sheet expansion device concerning an embodiment of the present invention. It is a figure which shows arrangement | positioning of each unit of the seat expansion apparatus shown in FIG. It is a perspective view of the wafer unit with which the wafer was supported by the annular frame via the expand sheet. It is a perspective view of an expanding unit. It is a perspective view of a heat shrink unit. It is a top view of the frame mounting plate provided with the notch part which enables access of a push pull conveyance apparatus. It is a fragmentary sectional view of a sheet expansion device showing a 1st embodiment of a detection means. It is a partial cross section side view which shows 2nd Embodiment of a detection means. 9 (A) to 9 (E) are partial cross-sectional side views showing the operation of the third embodiment of the detection means. It is a top view which shows 4th Embodiment of a detection means. It is sectional drawing which shows the wafer division | segmentation process by a sheet expand. It is sectional drawing which shows the heat shrink process of an expanded sheet. It is sectional drawing which shows the continuation of the heat shrink process of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a seat expansion device according to an embodiment of the present invention is shown. FIG. 2 is a diagram illustrating an arrangement of each unit of the seat expansion device according to the embodiment.

  In the sheet expanding apparatus 2 of the present embodiment, a cassette mounting table 4 that can be moved up and down by an elevator system is disposed on the front side of the apparatus. A cassette 6 containing a plurality of wafer units 17 shown in FIG. 3 is placed on the cassette mounting table 4.

  The wafer unit 17 is a workpiece unit in which a workpiece is attached to the surface of an expanded sheet T having an outer peripheral portion attached to an annular frame F. A semiconductor wafer (hereinafter simply abbreviated as a wafer) is used as the workpiece. The back surface of the sheet may be attached to an expanded sheet. The wafer 11 has a device 15 such as an LSI in each region partitioned by a plurality of division lines 13 formed in a lattice pattern on the surface.

  In the present embodiment, which is a sheet expansion apparatus, when the expanded sheet T is expanded to divide the wafer 11 into individual chips, the wafer 11 of the wafer unit 17 accommodated in the cassette 6 has a dividing line 13. A modified layer, a laser processing groove, a cutting groove, or the like serving as a division starting point is formed along.

  The wafer unit 17 pulled out from the cassette 6 placed on the cassette placing table 4 by the push-pull transfer device 8 is placed on a pair of centering bars 10 having an L-shaped cross section. Then, centering of the wafer unit 17 in the X-axis direction is achieved by moving the centering bars 10 toward each other.

  The wafer unit 17 that has been centered is attracted by the revolving transport unit 12 and placed on a pair of centering bars 16 disposed in the temporary placement area 14, and the centering bars 16 move in a direction toward each other. Thus, centering is achieved again.

  The wafer unit 17 centered in the temporary placement area 14 is pushed into the expanding unit (sheet expanding means) 20 shown in FIG. 4 by the push-pull transfer device 18 and placed on the frame placement plate 34.

  The expand unit 20 is disposed in a cooling chamber 21 defined by a housing 20a. A cooling air injection nozzle 23 is disposed in the cooling chamber 20, and the inside of the chamber 21 is maintained at a predetermined cooling temperature (for example, 5 ° C. to 10 ° C.).

  Reference numeral 32 denotes a frame pressing plate, and the frame pressing plate 32 and the frame mounting plate 34 constitute an annular frame fixing means 36 for fixing the annular frame F of the wafer unit 17. The frame pressing plate 32 is fixedly disposed, and the frame mounting plate 34 is disposed so as to be vertically movable by a plurality of air cylinders 38.

  A cylindrical push-up member 40 serving as a pressing portion is disposed corresponding to the opening of the frame mounting plate 34. The cylindrical push-up member 44 is lifted and lowered by a lifting mechanism 42 having a plurality of air cylinders.

  The wafer unit 17 in which the expanded sheet T is expanded by the expand unit 20 and the wafer 11 is divided into individual device chips 15 is pulled out from the expand unit 20 by the push-pull transfer device 18 and placed on the pair of centering bars 16. Then, centering in the X-axis direction is performed by the centering bar 16.

  The centered wafer unit 17 is sucked by the revolving transport unit 12 and transported to the heat shrink unit 22 shown in FIG. The heat shrink unit 22 includes a horizontally placed frame mounting plate 46, a frame pressing plate 48 moved in the Y-axis direction in FIG. 1 by an air cylinder 50, a cylindrical push-up member 54, and a negative pressure adsorption. And a suction table 56 of the type.

  The frame mounting plate 46 is moved in the vertical direction by the air cylinder 52. The cylindrical push-up member 54 is moved up and down by an elevating mechanism 58 having a plurality of air cylinders. The suction table 56 is moved in the vertical direction by a plurality of air cylinders different from the air cylinder that lifts and lowers the push-up member 54 disposed in the lifting mechanism 58. Reference numeral 24 denotes a heater as a heating means, which is arranged so as to be movable in the vertical direction.

  The wafer unit 17 from which the expanded sheet T that has been loosened by the heat shrink unit 22 is heated to remove the slack is adsorbed by the revolving transport unit 12 and placed on the spinner table 28 of the spin cleaning unit 26 for spin cleaning. Spin dried.

  The wafer unit 17 cleaned by the spin cleaning unit 26 is adsorbed by the revolving transfer unit 12 and placed on the pair of centering bars 10, and after being centered, is covered with the cover 30a by the push-pull transfer device 8. It is pushed into the cleaning unit (cleaning means) 30.

  The cleaning unit 30 is provided with a plurality of low-pressure mercury lamps (not shown) covered with a cover 30a. The low-pressure mercury lamp is turned on to irradiate the surface of the wafer 11 with ultraviolet rays to generate unstable active oxygen. The organic substances on the mounting surface of the wafer 11 are effectively removed by the generated active oxygen.

  Next, with reference to FIG. 6 to FIG. 10, detection means (detection unit) for detecting the positional deviation of the annular frame F of the wafer unit 17 placed on the frame placement plate 34 will be described. The detection of the positional deviation of the annular frame F according to the embodiment of the present invention is based on the premise that the outer periphery of the wafer 11 stuck on the expanded sheet T and the inner periphery of the annular frame F are arranged substantially concentrically. .

  As shown in FIG. 6, the frame mounting plate 34 is formed with a notch 34 </ b> A so that the push-pull conveying device 18 can access the frame mounting plate 34. In FIG. 6, the expanded sheet T and the wafer 11 of the wafer unit 17 are omitted so that the frame mounting plate 34 can be easily seen.

  Referring to FIG. 7, a cross-sectional view of the detection means of the first embodiment is shown. The detection means of the present embodiment is provided on the frame mounting plate 34 and includes an irradiation unit that irradiates light to the annular frame and a detection unit that detects reflection of light emitted from the irradiation unit. The first reflective photoelectric sensor 68 and the second reflective photoelectric sensor 70 are configured. Here, the first reflective photoelectric sensor 68 and the second reflective photoelectric sensor 70 are arranged on the frame mounting plate 34 so as to be just within the width of the annular frame F.

  Here, the frame mounting plate 34 constitutes a support surface of the annular frame fixing means 36 constituted by the frame mounting plate 34 and the pressing plate 32. As shown in FIG. 7, when the annular frame F is detected simultaneously by the first reflective photoelectric sensor 68 and the second reflective photoelectric sensor 70, the pressing portion (cylindrical push-up member) 40 is It is detected that the annular frame F is placed on the frame placement plate (support surface) 34 without deviation.

  On the other hand, when the annular frame F cannot be detected by any one of the first and second reflective photoelectric sensors 68 and 70, the annular frame F is displaced with respect to the pressing portion (cylindrical push-up member) 40. It is detected that

  When this positional deviation exceeds the allowable range, a warning is transmitted to the operator by a warning transmission means (not shown), and the annular frame F is gripped by the push-pull transfer device 18 shown in FIG. The wafer unit 17 is repositioned so that the annular frame F is placed at an appropriate position on the frame placement plate (support surface) 34.

  Here, the sheet expanding apparatus 2 has a controller (control means) for controlling the push-pull conveying apparatuses 8 and 18 and the swivel type conveying unit 12, and the control means is placed on the support surface 34. An allowable range storage unit that stores an allowable range of horizontal positional deviation with respect to the pressing unit (cylindrical push-up member) 40 of the wafer unit 17 and an allowable range in which the positional deviation detected by the detecting means is stored in the allowable range storage unit. A re-transfer command unit that controls the transfer means (push-pull transfer device) 18 to transfer again so that the annular frame F of the wafer unit 17 is properly placed on the support surface 34 when outside. .

  As a modification of the present embodiment, the first reflective photoelectric sensor 68 and the second reflective photoelectric sensor 70 may be disposed on the lower surface of the holding plate 32 with an appropriate interval. It should be noted that the frame pressing plate 32 shown in FIG. 4 is shown in an abbreviated form for easy understanding. Actually, as shown in FIG. 11, the frame pressing plate 32 is configured from a part of a box. And fixedly arranged.

  In the detection means of the first embodiment shown in FIG. 7, the first reflective photoelectric sensor 68 and the second reflective photoelectric sensor 70 are used. However, only one reflective photoelectric sensor may be used, and one photoelectric sensor. Is disposed at one of the positions of the first reflection type photoelectric sensor 68 or the second reflection type photoelectric sensor 70 shown in FIG. 7, so that the displacement of the annular frame F can be roughly detected.

  Referring to FIG. 8, there is shown a partial cross-sectional side view around the detection means of the second embodiment of the present invention. In the detection means of this embodiment, a distance sensor 72 is disposed on the front surface of the push-pull conveying device 18. As the distance sensor 72, a conventionally known optical or ultrasonic distance sensor can be adopted.

  As shown in FIG. 8, after the annular frame F is held by the pair of claws 19 of the push-pull transfer device 18 and the wafer unit 17 is placed on the frame placing plate 34, the distance sensor 72 is connected to the annular frame F. The push-pull conveying device 18 is lowered by a predetermined distance until the height becomes the same, and the distance sensor 72 is placed on the frame mounting plate 34 from a predetermined position whose distance is known from the center of the pressing portion (cylindrical push-up member) 40. The distance to the mounted annular frame F is measured.

  If this measurement distance is not within the allowable range, the annular frame F is again gripped by the pawl 19 of the push-pull conveying device 18, and the annular frame F of the frame unit 17 is repositioned so as to be in the correct position.

  Next, the detection means of 3rd Embodiment of this invention is demonstrated with reference to FIG. In the present embodiment, a light emitting portion 74 (irradiation portion) of an optical sensor is disposed on one of the pair of claws 19 of the push-pull conveying device 18, and a light receiving portion 76 (detection portion) is disposed on the other.

  First, as shown in FIG. 9A, the annular frame F of the wafer unit 17 is gripped by a pair of claws 19 of the push-pull transfer device 18, and the wafer unit 17 is positioned above the frame mounting plate 34 of the expand unit 20. Transport to.

  Next, as shown in FIG. 9B, the push-pull conveying device 18 is lowered and the annular frame F is placed on the frame placing plate 34. After the annular frame F is placed on the frame placement plate 34, the annular frame F is moved to a predetermined position by pushing the annular frame F with the push-pull conveying device 18, as shown in FIG. 9C.

  After the annular frame F is placed on the frame placement plate 34, the push-pull conveying device 18 is once retracted to the retracted position as shown in FIG. 9D. From this retracted position, as shown in FIG. 9 (E), the push-pull conveying device 18 moves relative to the annular frame F placed on the frame placing plate 34, and from the light emitting portion 74 of the optical sensor. The position where the light is blocked by the annular frame F is detected.

  It is determined whether or not the annular frame F is placed at a predetermined position from the amount of movement of the push-pull conveying device 18 from the retracted position to the position where the annular frame F is detected.

  If it is determined that the annular frame F is not placed at the predetermined position, the annular frame F is gripped by the pair of claws 19 of the push-pull conveying device 18 and the annular frame F is placed on the frame placing plate 34 again. The operations from (C) to FIG. 9 (E) are repeated to detect whether or not the annular frame F is placed at a predetermined position.

  Referring to FIG. 10, there is shown a plan view for explaining the detection means of the fourth embodiment of the present invention. In the present embodiment, a camera is disposed above the frame mounting plate 34 so that, for example, the imaging region 74 is the region shown in FIG.

  The push-pull transfer device 18 images the wafer unit 17 mounted on the frame mounting plate 34 of the expand unit 20 with a camera, detects the positions of the annular frame F and the wafer 11 on the captured image, and the annular frame F The position shift of the annular frame F is detected based on whether or not the position is shifted from the reference position.

  When the positional deviation is detected, the annular frame F of the wafer unit 17 is gripped by the pair of claws 19 of the push-pull transfer device 18, and the wafer unit 17 is placed on the frame so that the annular frame F is in the correct position. Place on plate 34 again. In FIG. 10, an arrow A indicates the loading / unloading direction of the frame unit 17.

  Next, with reference to FIG. 11, the dividing process of the wafer 11 by the expanding unit (sheet expanding means) 20 will be described. The wafer unit 17 centered by the centering bar 16 in the temporary placement area 14 is pushed into the expand unit 20 by the push-pull transfer device 18 and placed on the frame placement plate 34 as shown in FIG. The

  In this state, it is detected whether or not the annular frame F described with reference to FIGS. 6 to 9 is placed at a predetermined position on the frame placement plate 34 with respect to the pressing portion (cylindrical push-up member) 40. Perform the process.

  Next, the air cylinder 38 is operated to raise the frame mounting plate 34, and as shown in FIG. 11B, the annular frame F of the wafer unit 17 is formed into an annular shape composed of the frame mounting plate 34 and the frame pressing plate 32. It is clamped by the frame fixing means 36 and fixed.

  Next, the air cylinder 44 is actuated to move the cylindrical push-up member (pressing portion) 34 upward, so that the expanded sheet T is pushed up by the cylindrical push-up member 34 as shown in FIG. Is expanded (expanded) in the radial direction.

  Since the expanded sheet T is expanded in the radial direction, an external force acts on the wafer 11 adhered to the expanded sheet T in the radial direction, so that the wafer 11 has a modified layer formed along the scheduled division line 13 or the like. It is broken from the division starting point and divided into individual device chips 15.

  After the wafer 11 is divided into device chips 15, as shown in FIG. 11D, when the cylindrical push-up member 40 is lowered, the portion of the expanded sheet T pushed up, that is, the inner periphery of the annular frame F and the outer periphery of the wafer 11 The expansion sheet T between the two is slack.

  In the sheet expanding apparatus 2 of the present embodiment, the looseness of the expanded sheet T is removed by heating with the heat shrink unit 22. The wafer unit 17 in which the wafer 11 is divided into individual device chips 15 by the expand unit 20 is pulled out to the temporary placement area 14 by the push-pull transfer device 18, placed on the centering bar 16, and placed on the centering bar 16 by the X axis. Direction centering is performed.

  Next, the wafer unit 17 is adsorbed by the revolving transport unit 12, and the annular frame F of the wafer unit 17 is placed on the frame placement plate 46 of the heat shrink unit 22.

  Next, with reference to FIG.12 and FIG.13, the removal of the slack part of the expanded sheet T in the heat shrink unit 22 is demonstrated. First, the air cylinder 50 is operated to move the frame pressing plate 48 onto the frame mounting plate 46.

  Next, the air cylinder 52 is actuated to raise the frame mounting plate 46, and the annular frame F of the wafer unit 17 is held between the frame mounting plate 46 and the frame pressing plate 48 as shown in FIG. And fix.

  Next, the air cylinders 60 and 62 disposed in the elevating mechanism 58 are simultaneously operated to push up simultaneously with the cylindrical push-up member 54 and the suction table 56 as shown in FIG. Thereby, the slack portion of the expanded sheet T is pushed up, the expanded sheet T is expanded again in the radial direction, and the interval between the adjacent device chips 15 is widened.

  When the suction table 56 communicates with the suction unit 64 in this state, the wafer 11 is sucked to the suction table 56 via the expanded sheet T, and the wafer 11 is sucked to the suction table 56 with the space between the device chips widened. Retained.

  In this state, as shown in FIG. 12C, when the air cylinder 60 is operated to lower the cylindrical push-up member 54, the slack portion is again between the inner periphery of the annular frame F and the outer periphery of the wafer 11. It is formed.

  In this state, as shown in FIG. 13A, the heater 24 is lowered, and the slack portion of the expanded sheet T is heated by the heater 24. The slack portion of the heated expanded sheet T is loosened and contracted as shown in FIG.

  Heating of the slack area of the expanded sheet T is performed in a state where the expanded sheet T is sucked by the suction table 56. Therefore, the wafer 11 is held with a sufficient space between the adjacent device chips 15 secured.

  Since the expanding device (seat expanding device) 20 of the above-described embodiment of the present invention includes the detection means for detecting the positional deviation of the annular frame F with respect to the pressing portion (cylindrical push-up member) 40, the annular frame F is the pressing portion. (Cylindrical push-up member) The expansion of the expanded sheet T can be prevented from being performed while being displaced with respect to the position. Therefore, it is possible to prevent the generation of an undivided area of the wafer 11 and the generation of a chip space expansion failure area.

  In addition, in addition to the wafer in which the modified layer, the laser processing groove, or the cutting groove is formed, the workpiece to be processed in the expand unit 20 of the present embodiment is the back surface of the wafer after DBG (Dicing Before Grinding). And a wafer after DAF (Die Attach Film), SDBG (Stealth Dicing Before Grinding), and the like.

  In addition to expanding the sheet to divide the wafer into individual chips, for example, when expanding an expanded sheet to form a gap between adjacent chips in a wafer divided into individual chips. The seat expansion device is suitable.

2 Sheet expansion device 4 Cassette mounting table 6 Cassettes 8 and 18 Push-pull transfer device 10 and 16 Centering bar 11 Semiconductor wafer 12 Revolving transfer unit 17 Wafer unit 20 Expanding unit 22 Heat shrink unit 26 Spin cleaning unit 30 Cleaning unit 32 Presser Plate 34 Frame mounting plate 36 Annular frame fixing means 40 Pressing portion (cylindrical push-up member)
68, 70 Reflective photoelectric sensor 72 Distance sensor 74 Light emitting unit 76 Light receiving unit 78 Imaging region

Claims (4)

A dividing starting point is formed along a plurality of intersecting division lines, or an annular frame having an opening in the center through an expanded sheet attached to the back surface of a workpiece divided into individual chips. In a workpiece unit in a form in which a workpiece is supported, a sheet expansion device for expanding the expanded sheet,
An annular frame fixing means having a support surface for supporting the annular frame of the workpiece unit, and fixing the annular frame placed on the support surface;
Expansion means for expanding the expanded sheet by pressing the expanded sheet between the inner periphery of the annular frame fixed by the annular frame fixing means and the outer periphery of the workpiece with a pressing portion;
A cassette mounting table on which a cassette capable of accommodating a plurality of workpiece units is mounted;
Conveying means for conveying the workpiece unit from the cassette placed on the cassette mounting table so that the annular frame of the workpiece unit is placed on the support surface of the annular frame fixing means;
Detection means for detecting a horizontal displacement of the workpiece unit placed on the support surface with respect to the pressing portion;
A sheet extending apparatus comprising:   2. The sheet expanding apparatus according to claim 1, further comprising a warning transmission unit that issues a warning when the displacement detected by the detection unit exceeds an allowable range. A control means for controlling at least the transport means;
The control means includes an allowable range storage unit that stores an allowable range of horizontal displacement with respect to the pressing portion of the workpiece unit placed on the support surface;
When the positional deviation detected by the detection means is outside the allowable range stored in the allowable range storage unit, the conveying means is controlled so that the annular frame of the workpiece unit is placed on the support surface. The sheet expanding apparatus according to claim 1, further comprising a re-conveying instruction unit that conveys the sheet again.   The detection means includes an irradiation unit that irradiates light to the annular frame placed on the support surface, and a detection unit that detects any of transmission, reflection, and light shielding of the light irradiated from the irradiation unit. The seat expansion device according to any one of claims 1 to 3.