JP5715859B2 - Protective film coating method and protective film coating apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for coating a resin film on the surface of various wafers.

  A wafer on which a plurality of devices such as IC, LSI, etc. are partitioned by a planned dividing line and formed on the surface is divided into individual devices by laser irradiation along the planned dividing line, and is used for various electronic devices, etc. (For example, refer to Patent Document 1).

  When a laser beam is irradiated onto a wafer made of silicon, etc., there is a problem that debris scatters and adheres to the wafer surface, degrading the quality of the device. Therefore, the wafer surface is made of polyvinyl alcohol (PVA) or the like. The present applicant has proposed and put to practical use a technique for forming a protective film by coating a liquid resin, and protecting the surface of the device with the protective film even if debris is scattered to prevent quality degradation. (For example, refer to Patent Document 2).

  However, since the affinity between the liquid resin and the wafer is low, for example, when a protective film having a thickness of 4 μm is formed on the surface of a wafer having a diameter of 300 mm, the liquid resin such as PVA coated as the protective film is 0.3 cc. In spite of that, it is sufficient to use 19 to 30 cc of liquid resin, and nearly 98 to 99% of it is discarded, which is very uneconomical.

  Therefore, in order to solve such a problem, a method and an apparatus that can efficiently coat a liquid resin such as PVA are proposed by forming a water layer covering the surface of the wafer and dropping a liquid resin such as PVA. It has been put to practical use (see, for example, Patent Document 3).

JP-A-6-120334 JP 2004-188475 A JP 2010-125351 A

  However, due to the water repellency of the wafer and the inclination of the apparatus, there is a problem that it takes time of 100 seconds or more to form the water layer covering the surface of the wafer.

  The present invention has been made in view of such problems, and is to enable a liquid resin such as PVA to be efficiently coated on a wafer.

The first invention uses a protective film forming apparatus having a spinner table that holds a wafer in a state of being attached to a protective tape mounted on a ring-shaped frame, and covers the surface of the wafer with a liquid resin to form a protective film. The present invention relates to a protective film forming method to be formed, and includes the following steps.
(1) A frame holding step for holding a ring-shaped frame with a spinner table;
(2) A wafer holding process for holding the wafer surface upward with a spinner table,
(3) A concave portion forming process in which the ring-shaped frame is raised relative to the wafer to form a mortar-shaped concave portion between the ring-shaped frame and the wafer;
(4) A water layer forming step of forming a water layer covering the surface of the wafer held on the spinner table after the recess forming step,
(5) A liquid resin dropping step in which a liquid resin is dropped at the center of the wafer in the water layer,
(6) A resin film coating process in which the spinner table is rotated to disperse the water layer by centrifugal force acting on the water layer as the wafer rotates, and the dropped liquid resin is expanded to cover the surface of the wafer with the resin film. .

  In the above protective film forming method, in the resin coating process, the liquid resin dripped with the expansion of the water layer is expanded by lowering the frame relative to the wafer and returning the mortar shape to a flat shape. It is desirable to form a resin film on the surface of the wafer.

  A second invention relates to a protective film coating apparatus suitable for carrying out the above protective film forming method, a wafer holding means for holding a wafer attached to a protective tape attached to a ring-shaped frame, and a ring A spinner table having a ring-shaped frame holding means for holding a frame, a rotation driving means for rotationally driving the spinner table, a water supply means for supplying water to a wafer held on the spinner table, and a spinner table Liquid resin supply means for supplying liquid resin to the wafer, and vertical movement means for relatively moving the ring-shaped frame holding means and the wafer holding means up and down.

  In the resin film coating process according to the present invention, the ring-shaped frame with the wafer attached to the protective tape mounted on the ring-shaped frame is raised relative to the wafer to form a mortar shape between the ring-shaped frame and the wafer. After forming a concave portion and supplying water to the concave portion to form a water layer on the surface of the wafer, a liquid resin is dropped on the central portion of the wafer, and the spinner table is rotated to form a water layer by centrifugal force. Since the liquid resin dropped and expanded is coated with the resin film on the surface of the wafer, the liquid resin can be efficiently spread over the entire surface of the wafer and coated. Further, since most of the dropped liquid resin is coated on the surface of the wafer, it is extremely economical.

It is a perspective view which shows an example of a protective film coating | coated apparatus. It is sectional drawing which shows schematically the state hold | maintained on the spinner table with the wafer supported by the ring-shaped flame | frame via the protective tape. It is sectional drawing which shows schematically the state which raised the ring-shaped flame | frame and formed the recessed part with the surface of a wafer, and the protective tape. It is sectional drawing which shows roughly the state which supplies water to a recessed part and forms the layer of water on the surface of a wafer. It is sectional drawing which shows schematically the state which dripped liquid resin on the layer of water. It is sectional drawing which shows schematically the state which rotates a spinner table and scatters a layer of water and forms the resin film on the surface of a wafer.

1 Apparatus Configuration A protective film coating apparatus 1 shown in FIG. 1 is an apparatus that forms a protective film by coating a liquid resin on the surface of a wafer, and includes a spinner table 3 that can be rotated by being driven by a rotation driving means 2. Yes.

  The wafer W held on the spinner table 3 is attached to a protective tape T mounted so as to close the opening of the ring frame F. The spinner table 3 includes a wafer holding means 4 for holding the wafer W attached to the protective tape T attached to the ring-shaped frame F, and a ring-shaped frame integrated with the wafer W via the protective tape T. And a ring-shaped frame holding means 5 for holding F.

  Around the spinner table 3, water supply means 6 for supplying water to the wafer W held by the wafer holding means 4 of the spinner table 3 is disposed. The water supply means 6 includes a base portion 60 that can be swung in communication with a water source (not shown), and an ejection portion 61 that extends in the horizontal direction from the base portion 60 and has a tip portion curved downward.

  Around the spinner table 3, liquid resin supply means 7 for supplying liquid resin to the wafer W held by the wafer holding means 4 of the spinner table 3 is disposed. The liquid resin supply means 7 includes a base portion 70 that can be swung in communication with a liquid resin tank (not shown), and a dropping portion 71 that extends from the base portion 70 in the horizontal direction and has a tip portion curved downward.

  The wafer holding means 4 includes a holding table 40 capable of sucking and holding the wafer W via the protective tape T, a shaft portion 41 connected to the lower end of the holding table, and a lift drive unit 42 for moving the shaft portion 41 up and down. The shaft portion 41 and the lift drive portion 42 constitute a vertical movement means 43 that moves the holding table 40 up and down. As shown in FIG. 2, the holding table 40 includes a suction unit 40a that communicates with a suction source (not shown). 1, for example, an air cylinder and a piston rod can be used. The vertical movement means 43 moves the ring-shaped frame holding means 5 and the wafer holding means 4 up and down relatively. It functions as a means for operating. In FIG. 2 and subsequent figures, the vertical movement means 43 is not shown.

  As shown in FIG. 2, the ring-shaped frame holding means 5 includes a support base 50 that supports the ring-shaped frame F from below, a pressing portion 51 that is attached to the support base 50 and presses the ring-shaped frame F from above, and supports A plurality of shaft portions 52 coupled to the lower end of the base 50 and a plurality of lift drive portions 53 that lift and lower the shaft portions 52 are provided, and the support base 50 is moved up and down by the shaft portions 52 and the lift drive portions 53. The vertical movement means 54 is comprised. The pressing portion 51 can rotate around the rotation shaft 510 by air injection or the like. Moreover, as the raising / lowering drive part 53 and the axial part 52, an air cylinder and a piston rod can be used, for example. The vertical movement means 43 functions as a means for relatively moving the ring-shaped frame holding means 5 and the wafer holding means 4 up and down.

  As shown in FIG. 2, the rotational drive means 2 that rotationally drives the spinner table 3 includes a motor 20, a rotational shaft 21 that is rotationally driven by the motor 20, and a base 22 that rotates as the rotational shaft 21 rotates. The lifting / lowering drive unit 53 is fixed to the base 22. When the motor 20 rotates the rotating shaft 21, the base 22 is also rotated, and the wafer holding means 4 and the frame holding means 5 are configured to rotate. The base 22 includes a flat portion 220 and a hanging portion 221 that hangs downward from the peripheral edge thereof.

  Receiving means 8 is disposed below the spinner table 3. The receiving means 8 includes an inner wall 80 positioned on the inner peripheral side of the hanging portion 221 constituting the base 22, an outer wall 81 positioned on the outer peripheral side of the hanging portion 221, a lower end portion and an outer wall of the inner wall 80. The bottom plate 82 is connected to the lower end of 81.

2 Protective Film Coating Method Next, the operation of the protective film coating apparatus 1 when the protective film is coated on the surface W1 of the wafer W will be described. As shown in FIG. 2, a ring-shaped frame F is attached to the outer periphery of the protective tape T, the opening of the ring-shaped frame F is closed with the protective tape T, and the wafer W is applied to the blocked protective tape T. The back surface W2 is attached. In this manner, the wafer W is integrated with and supported by the ring-shaped frame F via the protective tape T, and the surface W1 of the wafer W is exposed upward.

(1) Frame holding step As shown in FIG. 2, the ring-shaped frame F integrated with the wafer W via the protective tape T is placed on the support base 50 of the frame holding means 5 of the spinner table 3. Then, the pressing portion 51 is rotated toward the support base 50 (in the direction of arrow A in FIG. 2), and the ring-shaped frame F is sandwiched and held between the support base 50 and the pressing portion 51.
(2) Wafer Holding Step As shown in FIG. 2, the wafer W integrated with the ring-shaped frame F via the protective tape T is placed on the holding table 40 of the wafer holding means 4 of the spinner table 3. Then, by applying a negative pressure to the suction portion 40a, the back surface W2 side of the wafer W is sucked and held via the protective tape T with the front surface W1 of the wafer W exposed on the upper side. Note that either the frame holding step or the wafer holding step may be performed first, or both steps may be performed simultaneously.
(3) Concave forming step After the frame holding step and the wafer holding step, the ring-shaped frame F is moved up relative to the wafer W. Specifically, the vertical movement means 54 of the frame holding means 5 shown in FIG. 3 raises the support base 50, the vertical movement means 43 of the wafer holding means 4 lowers the holding table 40, or the vertical movement means. 54 raises the support base 50 and the vertical movement means 43 lowers the holding table 40, whereby the frame holding means 5 and the wafer holding means 4 are relatively moved up and down. When the ring-shaped frame F is raised relative to the wafer W in this way, a height difference is generated between the wafer W and the frame F, and a slope 90 is formed by the protective tape T. The front surface W1 of the wafer W is defined as a bottom surface 91, and the bottom surface 91 and the inclined surface 90 form a mortar-shaped recess 9.

(4) Water Layer Formation Step After the recess formation step, as shown in FIG. 4, the water supply means 6 is swung to move the ejection portion 61 above the wafer W held on the spinner table 3. Water 610 is discharged from the water. As a result, water accumulates in the mortar-shaped recess 9 and a water layer 61a covering the surface W1 of the wafer W is formed.

(5) Liquid resin dropping step After the water layer forming step, the ejection portion 61 of the water supply means 6 is retracted from above the wafer W, and the liquid resin supply means 7 is swung as shown in FIG. Is moved above the center of the wafer W. And the liquid resin 710 is dripped from the dripping part 71 in the state. For example, when the diameter of the wafer W is 300 mm and a resin having a thickness of 4 μm is to be coated, a liquid resin 710 of about 2 cc is dropped. As the liquid resin 710, for example, polyvinyl alcohol having a viscosity of 50 to 70 centipoise can be used. The dropped liquid resin 710 stays on the water layer 61a due to its viscosity.

(6) Resin film coating step After the liquid resin dropping step, the mortar-shaped recess 9 is formed by lowering the ring-shaped frame holding means 5 relative to the wafer holding means 4 as shown in FIG. The spinner table 3 is rotated by returning to the flat state in which the level difference between the wafer W and the ring-shaped frame F is eliminated and the protective tape T is horizontal. Then, a centrifugal force acts on the water layer 61a with the rotation of the wafer W, and the water 61b forming the water layer 61a is scattered by the centrifugal force to the outer peripheral side, and the dropped liquid resin 710 is horizontal. The resin film 71a is formed on the front surface W1 of the wafer W by extending to the outer peripheral side in the direction and spreading over one surface W1 of the wafer W.

  As described above, the ring-shaped frame F is raised relative to the wafer to form a recess, and water is supplied to the recess to form a water layer on the surface of the wafer. After the dropping, the wafer is rotated to scatter the water layer and spin coat the liquid resin, whereby the resin film can be efficiently coated on the surface of the wafer.

1: Protective film coating device 2: Rotation drive means 20: Motor 21: Rotating shaft 22: Base 220: Plane portion 221: Hanging part 3: Spinner table W: Wafer W1: Front surface W2: Back surface T: Protective tape F: Ring Frame 4: wafer holding means 40: holding table 40a: suction part 41: shaft part 42: elevating drive part 43: vertical movement means 5: ring-shaped frame holding means 50: support base 51: pressing part 510: rotating shaft 52: Shaft part 53: Elevating drive part 54: Vertical movement means 6: Water supply means 60: Base 61: Jetting part 610: Water 61a: Water layer 7: Liquid resin supply means 70: Base 71: Dropping part 8: Receiving means 80 : Inner wall 81: Outer wall 82: Bottom plate 9: Recessed portion 90: Slope 91: Bottom

Claims (3)

Protective film forming method for forming a protective film by coating a liquid resin on the surface of a wafer using a protective film forming apparatus having a spinner table that holds the wafer in a state of being attached to a protective tape attached to a ring-shaped frame Because
A frame holding step of holding the ring-shaped frame by the spinner table;
A wafer holding step of holding the wafer surface upward with the spinner table;
A concave portion forming step of raising the ring-shaped frame relative to the wafer to form a mortar-shaped concave portion between the ring-shaped frame and the wafer;
A water layer forming step of forming a water layer covering the surface of the wafer held by the spinner table after the recess forming step;
A liquid resin dropping step in which a liquid resin is dropped at the center of the wafer in the water layer;
Resin film coating that rotates the spinner table to disperse the water layer by centrifugal force acting on the water layer as the wafer rotates and expands the dropped liquid resin to coat the surface of the wafer with a resin film Process,
A protective film forming method comprising: In the resin film coating step, the liquid resin dropped by the expansion of the water layer is expanded by returning the mortar shape to a flat shape by lowering the frame relative to the wafer. The protective film forming method according to claim 1, wherein a resin film is formed on the surface of the wafer. A protective film coating apparatus for forming a protective film by coating a liquid resin on the surface of a wafer,
A wafer holding means for holding a wafer attached to a protective tape attached to a ring-shaped frame, and a spinner table comprising a ring-shaped frame holding means for holding the ring-shaped frame;
A rotation drive means for rotating the spinner table;
Water supply means for supplying water to the wafer held on the spinner table;
Liquid resin supply means for supplying liquid resin to the wafer held by the spinner table;
A vertically moving means for relatively moving the ring-shaped frame holding means and the wafer holding means up and down;
A resin film coating apparatus comprising:

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