Resin sheet fixing device

Abstract

The present invention provides a resin sheet fixing device. The resin sheet fixing device is miniaturized. The sheet holding unit of the resin sheet fixing device includes: a Peltier element that is parallel to the sheet holding surface of the sheet holding table and has an upper surface close to the sheet holding surface and a lower surface away from the sheet holding surface; a DC power supply that supplies a DC current to the Peltier element; and a switch that switches the direction of the DC current supplied to the Peltier element. By flowing a current in the first direction through the Peltier element, the resin sheet is softened and heat-fused to the wafer. By switching the switch to flow a current in the second direction through the Peltier element, the resin sheet held on the sheet holding surface is hardened and fixed to one surface of the wafer.

Description

Technical Field

[0001] The present invention relates to a resin sheet fixing device. Background Art

[0002] A wafer in which devices are respectively formed in regions divided by a plurality of intersecting division predetermined lines is known. The wafer is divided along the division predetermined lines to obtain chips. In this dicing process, in order to suppress the scattering of the chips accompanying the dicing, for example, a tape is pasted on one surface of the wafer as disclosed in Patent Document 1.

[0003] In this technique, after the dicing process, the chips are picked up from the tape. At this time, the paste of the tape may adhere to the chips. As a countermeasure, in the technique disclosed in Patent Document 2, a polyolefin-based resin sheet is heated and heat-sealed on one surface of the wafer, and then cooled and solidified. Such a resin sheet becomes a substitute for the tape. In this technique, after the dicing process, the chips are picked up from the resin sheet without paste. Therefore, the paste does not adhere to the chips.

[0004] In this technique, the resin sheet is heat-sealed on one surface of the wafer. Therefore, the resin sheet holding unit for holding the resin sheet has a heater. In addition, in order to cool and solidify the resin sheet heat-sealed to the wafer, the sheet holding unit is separated from the wafer.

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2003-077869

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2019-140387

[0007] In the above technique, the processing apparatus has: a heating table for heat-sealing a resin sheet to a wafer; and a cooling table for cooling the resin sheet heat-sealed to the wafer. In addition, the processing apparatus has a transfer mechanism for transferring the wafer heat-sealed with the resin sheet from the heating table to the cooling table.

[0008] Thus, the processing apparatus of the prior art has two tables and a transfer mechanism, so it is difficult to miniaturize. In addition, time is spent on transferring the wafer. In addition, since the resin sheet solidifies after being transferred from the heating table to the cooling table, the thickness accuracy of the resin sheet deteriorates. Summary of the Invention

[0009] Accordingly, an object of the present invention is to provide a resin sheet fixing device that is miniaturized and can make the thickness of the heat-sealed resin sheet uniform.

[0010] According to the present invention, there is provided a resin sheet fixing device, wherein the resin sheet fixing device includes: a sheet holding unit including a sheet holding table having a sheet holding surface for holding a resin sheet; a wafer holding table for holding a wafer; a vertical movement mechanism for relatively moving the sheet holding unit and the wafer holding table in a vertical direction perpendicular to the sheet holding surface; and a control unit for controlling the vertical movement mechanism. The sheet holding unit includes: a Peltier element disposed inside the sheet holding unit, parallel to the sheet holding surface and having an upper surface close to the sheet holding surface and a lower surface away from the sheet holding surface; a DC power supply for supplying a DC current to the Peltier element; and a switch for switching the direction of the DC current supplied to the Peltier element between a first direction for heating the upper surface of the Peltier element and a second direction opposite to the first direction for cooling the upper surface of the Peltier element. The control unit controls the vertical movement mechanism to press the resin sheet held by the sheet holding surface with the wafer held by the wafer holding unit, and controls the switch to make the DC current flow in the first direction, thereby heating the upper surface of the Peltier element to soften the resin sheet and thermally bond it to the wafer. The control unit controls the switch to make the DC current flow in the second direction, thereby cooling the upper surface of the Peltier element to harden the resin sheet held by the sheet holding surface and fix it to one surface of the wafer.

[0011] In this resin sheet fixing device, in a state where the resin sheet is held by the sheet holding surface, the direction of the current flowing on the upper surface of the Peltier element disposed near the sheet holding surface is switched, so as to fix the resin sheet to one surface of the wafer. That is, in a state where the resin sheet is placed on the sheet holding surface, thermocompression bonding and cooling of the resin sheet are performed to fix the resin sheet to the wafer.

[0012] Therefore, compared with a structure using two tables for fixing the resin sheet, the number of tables can be reduced, and a unit for transporting the resin sheet between the tables is not required. Thus, it is easy to simplify and miniaturize the structure of this resin sheet fixing device.

[0013] In addition, the resin sheet thermally bonded to the wafer on the sheet holding surface is directly cooled without being transported to other components. Therefore, the thickness accuracy of the resin sheet fixed to the wafer can be improved, that is, the thickness of the fixed resin sheet can be made uniform.

[0014] In addition, in this resin sheet fixing device, the upper surface of the Peltier element is heated to heat the sheet holding surface and the resin sheet placed thereon. At this time, the lower surface of the Peltier element is cooled, so that the cooling effect of cooling the sheet holding surface can be improved in the next process. Therefore, the time required to fix the resin sheet to the wafer can be shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a cross-sectional view showing the structure of the resin sheet fixing device.

[0016] Figure 2 is a cross-sectional view showing the resin sheet loading process in the resin sheet fixing device.

[0017] Figure 3 is a cross-sectional view showing the wafer holding process in the resin sheet fixing device.

[0018] Figure 4 is a cross-sectional view showing the wafer pressing process in the resin sheet fixing device.

[0019] Figure 5 is a cross-sectional view showing the heating (hot melting) process in the resin sheet fixing device.

[0020] Figure 6 is a cross-sectional view showing the cooling (hardening) process in the resin sheet fixing device.

[0021] Figure 7 is a cross-sectional view showing the separation process in the resin sheet fixing device.

[0022] Figure 8 is a cross-sectional view showing the wafer unloading process in the resin sheet fixing device.

[0023] REFERENCE NUMERAL DESCRIPTION

[0024] 1: Resin sheet fixing device; 2: Vacuum forming chamber; 3: Cover; 5: Cover opening / closing mechanism; 7: Vacuum pump; 10: Wafer holding unit; 12: Wafer holding table; 13: Wafer holding surface; 14: Air supply source; 15: Ventilation path; 16: Suction source; 20: Sheet holding unit; 22: Sheet support table; 23: Sheet holding surface; 24: Peltier element; 24a: Upper surface; 24b: Lower surface; 25: First power line; 26: Second power line; 27: Switch; 28: DC power supply; 30: Vertical movement mechanism; 60: Load detector; 40: Wafer transfer mechanism; 50: Sheet transfer mechanism; 70: Control unit; S: Resin sheet; W: Wafer; Wb: Second surface. DETAILED DESCRIPTION OF THE INVENTION

[0025] Figure 1The resin sheet fixing device 1 of the present embodiment shown fixes (forms) the resin sheet S held by the sheet holding surface 23 of the sheet holding unit 20 on one surface of the wafer W.

[0026] The resin sheet fixing device 1 includes: a wafer holding unit 10 that holds the wafer W through the wafer holding surface 13 in the vacuum forming chamber 2; a sheet holding unit 20 that holds the resin sheet S through the sheet holding surface 23; and a vertical movement mechanism (vertical movement mechanism) 30.

[0027] The vacuum forming chamber 2 is a housing of the resin sheet fixing device 1 capable of making the inside vacuum, and it has an opening 4, a cover 3 capable of covering the opening 4, a cover opening / closing mechanism 5 for opening and closing the cover 3, and a vacuum pump 7 for making the inside of the vacuum forming chamber 2 vacuum.

[0028] The wafer holding unit 10 includes: support columns 11 that penetrate and extend through the upper surface of the vacuum forming chamber 2; and a wafer holding table 12 that is provided at the lower end of the support columns 11 and is disposed inside the vacuum forming chamber 2. In addition, the lower surface of the wafer holding table 12 becomes a wafer holding surface 13 for sucking and holding the wafer W. In addition, a vacuum seal 2a for maintaining the vacuum inside the vacuum forming chamber 2 is provided at the penetrating portion of the support columns 11 on the upper surface of the vacuum forming chamber 2.

[0029] An air passage 15 connected to the air supply source 14 and the suction source 16 is provided in the support columns 11 and the wafer holding table 12. The wafer holding surface 13 in the wafer holding table 12 is configured to be selectively communicated with the air supply source 14 and the suction source 16 via the air passage 15. The wafer holding unit 10 can suck and hold the wafer W through the wafer holding surface 13 communicated with the suction source 16.

[0030] The sheet holding unit 20 includes: support columns 21 that penetrate and extend through the bottom surface of the vacuum forming chamber 2; and a sheet support table 22 that is provided at the upper end of the support columns 21 and is disposed inside the vacuum forming chamber 2. In addition, the upper surface of the sheet support table 22 becomes a sheet holding surface 23 for placing the resin sheet S.

[0031] The sheet holding surface 23 is arranged to face the wafer holding surface 13 of the wafer holding unit 10. In addition, a vacuum seal 2b for maintaining the vacuum inside the vacuum forming chamber 2 is provided at the penetrating portion of the support columns 21 on the bottom surface of the vacuum forming chamber 2.

[0032] In addition, the resin sheet fixing device 1 has a wafer transfer mechanism 40 and a sheet transfer mechanism 50. The wafer transfer mechanism 40 and the sheet transfer mechanism 50 are transfer components such as robot arms. These wafer transfer mechanism 40 and sheet transfer mechanism 50 can be different components or a common component.

[0033] The wafer transfer mechanism 40 transfers the wafer W from the outside to the vacuum forming chamber 2. The wafer transfer mechanism 40 can dispose the wafer W via the opening 4 at a position in the vacuum forming chamber 2 that faces the wafer holding surface 13 of the wafer holding unit 10. In the wafer holding unit 10, the wafer W thus disposed can be attracted and held by the wafer holding surface 13 communicated with the suction source 16.

[0034] The sheet transfer mechanism 50 can transfer the resin sheet S from the outside to the resin sheet fixing device 1. The sheet transfer mechanism 50 places the resin sheet S via the opening 4 of the vacuum forming chamber 2 on the sheet holding surface 23 of the sheet holding unit 20 in the vacuum forming chamber 2.

[0035] The vertical movement mechanism 30 is disposed on the upper surface of the vacuum forming chamber 2 and is connected to the support column 11 of the wafer holding unit 10. The vertical movement mechanism 30 moves the wafer holding unit 10 and the sheet holding unit 20 relatively in the vertical direction, i.e., the Z-axis direction, perpendicular to the sheet holding surface 23. In the present embodiment, the vertical movement mechanism 30 moves the support column 11 of the wafer holding unit 10 in the Z-axis direction. That is, the vertical movement mechanism 30 is configured to move the wafer holding unit 10 relative to the fixed sheet holding unit 20 in the Z-axis direction.

[0036] Specifically, the vertical movement mechanism 30 includes: an arm 31, which is connected to the support column 11 and extends in the horizontal direction; a drive rod 32, which is connected to the arm 31 and extends along the Z-axis direction; and a sensor 35, which detects the movement distance. The drive rod 32 is moved up and down by a drive source (not shown), so that the arm 31 and the wafer holding unit 10 (support column 11) connected to the arm 31 move up and down in the Z-axis direction. The movement distance of the wafer holding unit 10 is detected by the sensor 35.

[0037] In addition, the resin sheet fixing device 1 has a load detector 60. The load detector 60 is connected to the support column 11 of the wafer holding unit 10 via the vertical movement mechanism 30. The load detector 60 detects the load applied to the wafer holding unit 10 when the wafer holding unit 10 and the sheet holding unit 20 abut against each other with the wafer W and the resin sheet S interposed therebetween (i.e., the force with which the wafer W presses the resin sheet S).

[0038] In addition, the sheet holding unit 20 of the present embodiment has a Peltier element 24 inside. The Peltier element 24 has, for example, a flat plate shape and is disposed in parallel with the sheet holding surface 23 near the sheet holding surface 23 of the sheet support table 22 of the sheet holding unit 20. The Peltier element 24 is parallel to the sheet holding surface 23 and has an upper surface 24a close to the sheet holding surface 23 and a lower surface 24b away from the sheet holding surface 23.

[0039] In addition, one ends of a first power line 25 and a second power line 26 that are wound around inside the support columns 21 and the wafer support table 22 are attached to both ends of the Peltier element 24. The other ends of the first power line 25 and the second power line 26 are connected to a DC power supply 28 via a switch 27.

[0040] The DC power supply 28 is a power supply that supplies a DC current to the Peltier element 24. The switch 27 has a function of connecting the DC power supply 28 to the Peltier element 24 via the first power line 25 and the second power line 26, and a function of switching the direction of the DC current flowing from the DC power supply 28 to the Peltier element 24 via the first power line 25 and the second power line 26.

[0041] That is, the switch 27 is configured to switch the direction of the DC current supplied to the Peltier element 24 between a first direction for heating the upper surface 24a of the Peltier element 24 and a second direction for cooling the upper surface 24a of the Peltier element 24, and the second direction is a direction opposite to the first direction. In addition, regarding the lower surface 24b of the Peltier element 24, it is cooled when the DC current flows in the first direction, and heated when the DC current flows in the second direction.

[0042] In addition, the resin sheet fixing device 1 has a control unit 70 that controls each component of the resin sheet fixing device 1, and the control unit 70 has a computer. The control unit 70 controls each component of the resin sheet fixing device 1 described above to fix (form) the resin sheet S on one surface of the wafer W.

[0043] Next, the fixing operation of the resin sheet S relative to the wafer W in the resin sheet fixing device 1 will be described.

[0044] First, the control unit 70 controls the cover opening / closing mechanism 5 to open the cover 3 of the vacuum forming chamber 2, exposing the opening 4. And the control unit 70 moves the sheet transfer mechanism 50 holding the resin sheet S in the -X direction, thereby transferring the resin sheet S into the vacuum forming chamber 2 from the exposed opening 4. In addition, the control unit 70 controls the sheet transfer mechanism 50 to place the resin sheet S on the sheet holding surface 23 of the sheet holding unit 20 (resin sheet transfer process) as shown in Figure 2 shown.

[0045] Next, the control unit 70 connects the suction source 16 shown in Figure 1 to the wafer holding surface 13 of the wafer holding unit 10. Thereby, the wafer holding surface 13 becomes a negative pressure. In addition, the control unit 70 moves the wafer transfer mechanism 40 holding the wafer W in the -X direction, thereby transferring the wafer W into the vacuum forming chamber 2 from the exposed opening 4 and disposing it at a position facing the wafer holding surface 13. In addition, as shown in Figure 3As shown, the control unit 70 sucks and holds the first surface (the other surface) Wa of the wafer W through the wafer holding surface 13. Thereby, the wafer W is disposed above the resin sheet S held by the sheet holding surface 23 in a state where the second surface (one surface) Wb faces the resin sheet S (wafer holding process).

[0046] Next, the control unit 70 controls Figure 1 the cover opening / closing mechanism 5 shown in FIG. to close the cover 3 of the vacuum forming chamber 2 and seal the opening 4.

[0047] The control unit 70 controls the vertical movement mechanism 30 to move the wafer holding unit 10 downward along the Z-axis direction. Thereby, as Figure 4 shown, the wafer W held by the wafer holding surface 13 of the wafer holding unit 10 abuts against the resin sheet S held by the sheet holding surface 23 of the sheet holding unit 20 (wafer contact process).

[0048] In this way, the control unit 70 controls the vertical movement mechanism 30 to bring the second surface Wb of the wafer W held by the wafer holding unit 10 into contact with the resin sheet S held by the sheet holding surface 23 (pressing with a relatively weak force). In this state, the control unit 70 controls the vacuum pump 7 to perform vacuum suction on the inside of the vacuum forming chamber 2.

[0049] Then, when the air pressure inside the vacuum forming chamber 2 becomes equal to or lower than a specified value, the control unit 70 further moves the wafer holding unit 10 downward, so as to press the resin sheet S with a stronger force through the second surface Wb of the wafer W (wafer pressing process). In this way, the control unit 70 controls the vertical movement mechanism 30 to press the resin sheet S held by the sheet holding surface 23 through the wafer W (the second surface Wb) held by the wafer holding unit 10.

[0050] In addition, in this state, the control unit 70 controls Figure 1 the switch 27 shown in FIG. to connect the DC power supply 28 to the Peltier element 24 via the first power line 25 and the second power line 26. And the control unit 70 controls the switch 27 to set the direction of the DC current from the DC power supply 28 as shown by the arrow D1 in Figure 5 FIG. to be the first direction for heating the upper surface 24a of the Peltier element 24 (indicated by "h" in the figure).

[0051] In this way, while the control unit 70 presses the resin sheet S against the second surface Wb of the wafer W, a direct current flows in the first direction, thereby heating the upper surface 24a of the Peltier element 24, heating the sheet holding surface 23 and the resin sheet S held by the sheet holding surface 23, and softening the resin sheet S to thermally bond it to the second surface Wb of the wafer W (heating (thermal bonding) process). Additionally, at this time, the lower surface 24b of the Peltier element 24 is cooled (indicated by "c" in the figure).

[0052] After thermally bonding the resin sheet S to the wafer W, the control unit 70 controls the switch 27 (refer to Figure 1 ) to cause a direct current from the direct current power supply 28 to flow in the second direction, which is opposite to the first direction and cools the upper surface 24a of the Peltier element 24, as indicated by the arrow D2 in Figure 6 . Thereby, while the control unit 70 presses the resin sheet S against the second surface Wb of the wafer W, it cools the upper surface 24a of the Peltier element 24. By cooling the upper surface 24a in this way, the control unit 70 cools the sheet holding surface 23 and the resin sheet S held by the sheet holding surface 23, and hardens the resin sheet S to fix it on the second surface Wb of the wafer W (cooling (hardening) process). Additionally, at this time, the lower surface 24b of the Peltier element 24 is heated.

[0053] Next, the control unit 70 controls the switch 27 to disconnect the direct current power supply 28 from the Peltier element 24. And the control unit 70 controls the vertical movement mechanism 30 shown in Figure 1 to move the wafer holding unit 10 upward in the Z-axis direction and separate it from the sheet holding unit 20 (sheet holding surface 23), as shown in Figure 7 . That is, the control unit 70 separates the resin sheet S fixed to the second surface Wb of the wafer W from the sheet holding surface 23. Thereby, the control unit 70 can hold the wafer W with the resin sheet S fixed on the second surface Wb through the wafer holding surface 13 of the wafer holding unit 10 (separation process).

[0054] Next, the control unit 70 stops the vacuum pump 7 shown in Figure 1 , and controls the cover opening / closing mechanism 5 to open the cover 3 of the vacuum forming chamber 2, exposing the opening 4. Thereby, the vacuum inside the vacuum forming chamber 2 is broken.

[0055] Additionally, as shown in Figure 8As shown, the control unit 70 arranges the wafer transfer mechanism 40 to face the wafer holding surface 13 of the wafer holding unit 10 and contacts the resin sheet S covering the second surface Wb of the wafer W. In addition, the control unit 70 connects the wafer holding surface 13 of the wafer holding unit 10 to the air supply source 14. Thereby, the adsorption of the wafer holding surface 13 to the wafer W is released, and the wafer W is held by the wafer transfer mechanism 40.

[0056] Moreover, the control unit 70 moves the wafer W in the +X direction as indicated by the arrow E through the wafer transfer mechanism 40 and transfers it out of the vacuum forming chamber 2 through the opening 4 (wafer transfer process). In addition, the wafer transfer mechanism 40 can also hold the first surface Wa of the wafer W.

[0057] As described above, in the present embodiment, in a state where the resin sheet S is held by the sheet holding surface 23 of the sheet support table 22, the heating (hot melting) process and the cooling (hardening) process are performed by switching the direction of the current flowing through the upper surface 24a of the Peltier element 24 disposed near the sheet holding surface 23. And thereby the resin sheet S is fixed to the second surface Wb of the wafer W. That is, in the present embodiment, in a state where the resin sheet S is placed on the sheet holding surface 23 of one sheet support table 22, the hot melting and cooling of the resin sheet S are performed to fix the resin sheet S to the wafer W.

[0058] Therefore, compared with a structure that uses two tables to fix the resin sheet S, the number of tables can be reduced, and a unit for transferring the resin sheet between the tables is not required. Therefore, it is easy to simplify and miniaturize the structure of the resin sheet fixing device 1.

[0059] In addition, in a state where the resin sheet S held by the sheet holding surface 23 is pressed by the second surface Wb of the wafer W held by the wafer holding surface 13, the heating (hot melting) process and the cooling (hardening) process are performed. That is, the resin sheet S hot-melted to the wafer W is directly cooled without being transferred to other components. Therefore, the thickness accuracy of the resin sheet S fixed to the second surface Wb of the wafer W can be improved, that is, the thickness of the fixed resin sheet S can be made uniform.

[0060] In addition, in the present embodiment, in the heating (hot melting) process, the upper surface 24a of the Peltier element 24 is heated to heat the sheet holding surface 23 and the resin sheet S placed thereon. At this time, the lower surface 24b of the Peltier element 24 is cooled, so that in the subsequent cooling (hardening) process, the cooling effect of cooling the sheet holding surface 23 can be improved. Therefore, the time (the time of the cooling (hardening) process) for fixing the resin sheet S to the second surface Wb of the wafer W can be shortened.

[0061] In addition, in the present embodiment, a load detector 60 provided on the upper surface of the vacuum forming chamber 2 detects the load applied to the wafer holding unit 10 when the wafer holding unit 10 and the sheet holding unit 20 are in contact with each other with the wafer W and the resin sheet S interposed therebetween. Such a load detector may also be provided within the wafer holding table 12 of the wafer holding unit 10 or within the sheet supporting table 22 of the sheet holding unit 20.

Claims

1. A resin sheet fixing device, wherein, the resin sheet fixing device has: a sheet holding unit including a sheet holding table having a sheet holding surface for holding a resin sheet; a wafer holding table for holding a wafer; a vertical movement mechanism for relatively moving the sheet holding unit and the wafer holding table in a vertical direction perpendicular to the sheet holding surface; and a control unit for controlling the vertical movement mechanism, after the resin sheet is softened by heating and heat - welded to the wafer, it is fixed to the wafer by cooling and hardening, the sheet holding unit includes: a Peltier element disposed inside the sheet holding unit, parallel to the sheet holding surface and having an upper surface close to the sheet holding surface and a lower surface far from the sheet holding surface; a DC power supply for supplying a DC current to the Peltier element; and a switch for switching the direction of the DC current supplied to the Peltier element between a first direction for heating the upper surface of the Peltier element and a second direction opposite to the first direction for cooling the upper surface of the Peltier element, the control unit controls the vertical movement mechanism, presses the resin sheet held by the sheet holding surface with the wafer held by the wafer holding table, and controls the switch to make the DC current flow in the first direction, thereby heating the upper surface of the Peltier element to soften the resin sheet and heat - weld it to the wafer, the control unit controls the switch to make the DC current flow in the second direction, thereby cooling the upper surface of the Peltier element to harden the resin sheet held by the sheet holding surface and fix it to one surface of the wafer, heating and cooling of the resin sheet are performed in a state where the resin sheet held by the sheet holding surface is pressed against the entire one surface of the wafer held by the wafer holding table.

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