JP2015213111A - Sheet sticking method, sheet sticking device and wafer processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that it is desired to shorten the time required for preprocessing that is performed before processing a wafer into a plate, and it is desired to simplify a device configuration for the preprocessing.SOLUTION: In the state where a first face 20 of a flexible sheet 12 is exposed, a second side 22 is fitted to a support surface 14 and in the flexible sheet 12, at least a substantially entire portion to be fitted to a wafer 10 is flatly supported on the support surface 14. A liquid-state adhesive 26 is given to the first face 20 of the flexible sheet 12, a first principal surface 16 of the wafer 10 is made confront the first face 20 of the flexible sheet 12, and the first principal surface 16 is brought into contact with the liquid-state adhesive 26. The flexible sheet 12 supported on the support surface 14 is rotated together with the wafer 10, the liquid-state adhesive 26 is spread over a gap 28 between the first principal surface 16 and the first face 20, the liquid-state adhesive 28 is solidified thereafter, and the flexible sheet 12 flatly supported on the support surface 14 is fixed to the first principal surface 16 of the wafer 10.

Description

  The present invention relates to a sheet sticking method for sticking a sheet to a wafer. The present invention also relates to a sheet sticking apparatus for sticking a sheet to a wafer. The present invention also relates to a wafer processing method using a sheet sticking method.

  A wafer which is a material of a semiconductor element is manufactured by cutting a cylindrical ingot made of single crystal silicon or the like into a thin plate shape. Wafers obtained by cutting an ingot may have waviness or warpage due to cutting work. Conventionally, waviness and warpage are removed by subjecting a wafer obtained by cutting an ingot to steps such as grinding, polishing, and etching.

  For example, Patent Document 1 discloses a pretreatment technique when processing a wafer including waviness and warpage obtained by cutting an ingot into a flat plate by grinding. Patent Document 1 states that “The present invention is a resin coating method in which one surface of a wafer including waviness and warpage cut out from an ingot is ground and processed to be flat to coat the other surface of the wafer with resin. The other surface of the wafer is coated with an ultraviolet light curable resin, and the wafer coated with the ultraviolet light curable resin is exposed to one surface of the wafer on the holding surface of the stage having a substantially horizontal holding surface. A wafer holding step for holding the wafer, a pressing step for pressing the wafer held on the holding surface of the stage in the direction of the stage from one surface side of the wafer by the pressing means, and an ultraviolet ray after the pressing means is separated from the wafer. It is characterized by comprising at least a resin curing step of irradiating the ultraviolet light curable resin with ultraviolet light by the light irradiation means to cure the ultraviolet light curable resin. "(Paragraph 0009) “According to the present invention, the ultraviolet light curable resin is uniformly supplied to the other surface of the wafer by pressing the wafer with the pressing means. After the pressing step, the ultraviolet light is released after the pressing means is separated from the wafer. The cured resin is cured, so that the other surface of the wafer can be covered with the ultraviolet light curable resin without leaving any internal stress on the wafer, so that even if the resin is removed after grinding, springback does not occur. The wafer can be processed flat with high accuracy ”(paragraph 0010).

Japanese Patent No. 5089370

  In pre-processing performed before processing a wafer into a flat plate, it is desired that the time required for the pre-processing can be shortened and that the apparatus configuration for the pre-processing can be simplified.

  One aspect of the present disclosure is a sheet attaching method for attaching a sheet to a wafer, the step of preparing a wafer having a first main surface and a second main surface, and a shape that can substantially cover the first main surface A flexible sheet having a first surface and a second surface, a step of preparing a sheet support portion having a flat support surface, and exposing the first surface of the flexible sheet. In this state, the second surface is attached to the support surface to support the flexible sheet flatly on the support surface, and a liquid adhesive is applied to the first main surface of the wafer or the first surface of the flexible sheet. A step of allowing the first main surface of the wafer and the first surface of the flexible sheet to face each other so that both the first main surface and the first surface are in contact with the liquid adhesive; Rotating the flexible sheet and the wafer, the first main surface and the first surface And causing gaps to spread the liquid adhesive, solidifying the liquid adhesive is a sheet sticking method comprising the steps of fixing the flexible sheet to the wafer, the.

  Another aspect of the present disclosure is a sheet sticking apparatus that attaches a sheet to a wafer, the sheet support unit having a flat support surface capable of supporting a flexible sheet having a first surface and a second surface, and a flexible And a rotation driving unit that rotates the sheet supporting unit in a state where the wafer faces the first surface of the adhesive sheet.

  Still another aspect of the present disclosure is a wafer processing method including the above-described sheet sticking method, and after the step of solidifying the liquid adhesive, the step of grinding the second main surface of the wafer to process it into a flat surface Including a wafer processing method.

  According to the sheet sticking method according to one aspect, the flexible sheet covers the first main surface of the wafer while maintaining a flat shape even when the curved surface portion exists on the first main surface of the wafer. To do. Until the liquid adhesive solidifies, the wafer maintains its initial shape without substantial deformation. Therefore, when the wafer before applying the flexible sheet includes waviness or warpage, the wafer including the waviness or warpage in which the flexible sheet is attached to the first main surface is included. Then, in a subsequent step of the sheet sticking method, the second main surface of the wafer can be ground flat using the flat second surface of the flexible sheet as a reference surface. The first main surface of the wafer can be ground flat while being removed. The wafer after being ground flat in this way is flat without undulation or warping. When the liquid adhesive is spread over the gap between the first main surface of the wafer and the first surface of the flexible sheet, the wafer is not substantially deformed, so that the liquid adhesive is liquid immediately after the liquid adhesive is spread over the gap. The adhesive can be solidified, so that the time required for the pretreatment performed before processing the wafer into a flat plate can be shortened.

  According to the sheet sticking apparatus according to another aspect, by performing the above-described sheet sticking method, it is possible to reduce the time required for the pre-processing performed before processing the wafer into a flat plate, and to convert the wafer into a flexible sheet. Since a structure for pressing and spreading the liquid adhesive in the gap is not required, the apparatus configuration is simplified.

  Furthermore, according to the wafer processing method according to another aspect, a flat wafer can be produced by performing the above-described sheet sticking method as a pretreatment, and the total time required to process the wafer into a flat plate can be shortened.

It is a perspective view showing one step of a sheet sticking method by one embodiment of this indication. It is a front view which shows typically the other step of the sheet sticking method of FIG. It is a front view which shows typically the other step of the sheet sticking method of FIG. 1 typically. It is a front view which shows typically the other step of the sheet sticking method of FIG. 1 typically. It is a front view which shows typically the other step of the sheet sticking method of FIG. 1 typically. FIG. 2D is a front view schematically showing the final stage of the step of FIG. 2D. It is sectional drawing which shows typically the other step of the sheet sticking method of FIG. 1 typically. It is sectional drawing which shows typically the modification of the step of FIG. 3A. It is a front view which shows typically the modification of the step of FIG. 2D and FIG. 2E. It is a perspective view which shows an example of the positioning member used at the step of FIG. It is a perspective view which shows the other example of the positioning member used at the step of FIG. It is a top view which shows the other example of a positioning member of FIG. 5A. It is a perspective view which shows the other example of use of the positioning member of FIG. 5B. It is a top view which shows typically an example of arrangement | positioning of the positioning member used at the step of FIG. It is a top view which shows typically the other example of arrangement | positioning of the positioning member used at the step of FIG. It is a top view explaining the shape of the positioning member used at the step of FIG. It is a front view showing typically the sheet sticking device by one embodiment of this indication. It is a front view which shows the sheet sticking apparatus of FIG. 9A in another operation state. It is a partial cross section front view which shows typically the other modification of the sheet sticking apparatus of FIG. 9A. It is a partial cross section front view which shows the sheet sticking apparatus of FIG. 10A in another operation state. It is sectional drawing which shows typically the modification of the sheet sticking apparatus of FIG. 9A. It is a front view which shows typically the other modification of the sheet sticking apparatus of FIG. 9A typically. It is a front view showing typically one step of a wafer processing method by one embodiment of this indication. It is a front view which shows typically the other step of the wafer processing method of FIG. 13A. FIG. 13B is a front view schematically showing still another step of the wafer processing method in FIG. 13A.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.
1 to 8 schematically show an embodiment of a sheet sticking method according to one aspect of the present disclosure. The illustrated sheet affixing method is a method of affixing a flexible sheet (referred to as a flexible sheet in the present application) to a wafer that is a material of a semiconductor element, and includes, for example, undulation obtained by cutting an ingot. This can be carried out as a pretreatment performed before processing a wafer including warpage into a flat plate. In addition, the use of the sheet sticking method according to the present disclosure is not limited to this.

  In the illustrated sheet sticking method, as shown in FIG. 1, a wafer 10, a flexible sheet 12, and a flat support surface 14 are prepared. The wafer 10 is a disk-shaped element having a first main surface (lower surface in the drawing) 16 and a second main surface (upper surface in the drawing) 18 on the opposite side. The wafer 10 is, for example, a state in which a cylindrical ingot made of single crystal silicon or the like is cut into a thin plate shape, and undulation or warping may occur due to the cutting operation. The wafer 10 having waviness and warpage includes a curved surface in at least a part of the first main surface 16 and the second main surface 18 in a state where no external force is applied to the wafer 10 itself.

  The flexible sheet 12 has a shape and a dimension that can substantially cover the first main surface 16 of the wafer 10. “Substantially coatable” means that there may be a region that is slightly uncoverable along the outer edge of the first major surface 16 (eg, a region that is about 5% or less of the surface area of the first major surface 16). . In addition, the flexible sheet 12 may have a shape and a dimension that are the same as or larger than the first main surface 16 of the wafer 10. The flexible sheet 12 has a first surface (upper surface in the drawing) 20 and a second surface (lower surface in the drawing) 22 on the opposite side, and has, for example, a disk-like shape that is the same as or similar to the wafer 10, and The thickness may be smaller than that of the wafer 10. In addition, the flexible sheet 12 can have flexibility that can follow the shape of the surface when the sheet is spread flat on the surface of an arbitrary object. The flexible sheet 12 can be made of, for example, a resin film, paper, cloth, wood, metal, or the like.

  The support surface 14 is one surface of the sheet support portion 24 having an arbitrary structure, and supports the flexible sheet 12 in a state where the flexible sheet 12 is spread flat, and also supports the flexible sheet 12 in the axis 14a. Can be rotated around. The support surface 14 has a shape and a dimension that can support at least substantially the entire portion of the flexible sheet 12 that is attached to the wafer 10 in a flat manner. The support surface 14 may have a circular contour that is the same as or similar to the contour of the wafer 10. The support surface 14 can have rigidity capable of maintaining a state in which the flexible sheet 12 is supported flat against an external force. The sheet support 24 having the support surface 14 can be, for example, a circular table.

  In the illustrated sheet sticking method, the second surface 22 is attached to the support surface 14 with the first surface 20 of the flexible sheet 12 exposed, and the flexible sheet 12 is attached to at least the wafer 10. The method includes a step (FIG. 2A) of supporting substantially the entire portion on the support surface 14 in a flat manner. In the embodiment shown in FIG. 2A, the support surface 14 has a slightly smaller dimension than the flexible sheet 12 and is an annular region along the outer edge of the flexible sheet 12 (eg, about 1 mm wide in the radial direction from the outer edge). The part except the area is supported flat. In this portion excluding the annular region, the second surface 22 of the flexible sheet 12 is held in close contact with the support surface 14.

  The illustrated sheet sticking method includes a step (FIG. 2B) of applying a liquid adhesive 26 to the first main surface 16 of the wafer 10 or the first surface 20 of the flexible sheet 12. In the embodiment shown in FIG. 2B, a predetermined amount of liquid adhesive 26 is supplied to the central region of the first surface 20 of the flexible sheet 12 that is flatly supported by the support surface 14.

  In the illustrated sheet sticking method, the first main surface 16 of the wafer 10 and the first surface 20 of the flexible sheet 12 are opposed to each other, and both the first main surface 16 and the first surface 20 are liquid adhesive. 26 (FIG. 2C). In the embodiment shown in FIG. 2C, the first of the flexible sheet 12 is positioned in a state where the wafer 10 is positioned in a predetermined relative positional relationship substantially parallel to the flexible sheet 12 that is flatly supported on the support surface 14. The central region of the first main surface 16 of the wafer 10 is brought into contact with the liquid adhesive 26 supplied to the central region of the surface 20.

  In the illustrated sheet sticking method, the sheet support 24, the flexible sheet 12, and the wafer 10 are rotated to spread the liquid adhesive 26 in the gap 28 between the first main surface 16 and the first surface 20. Step (FIG. 2D, FIG. 2E) is included. In the embodiment shown in FIGS. 2D and 2E, the sheet support 24 having the support surface 14 is rotated at a high speed around the axis 14a to rotate the flexible sheet 12 closely supported by the support surface 14, and liquid adhesion The wafer 10 disposed opposite to the flexible sheet 12 through the agent 26 can be rotated so as to be dragged by the flexible sheet 12. Alternatively, the sheet support 24 supporting the flexible sheet 12 is rotated at a high speed around the axis 14 a, and at the same time, a wafer support (not shown) supporting the wafer 10 is rotated at a high speed in synchronization with the sheet support 24. It can also be set as the structure to make. As the wafer 10 and the flexible sheet 12 rotate at a high speed, the liquid adhesive 26 flows radially from the central region of the first main surface 16 and the first surface 20 toward the outer edge due to centrifugal force, and the gap 28 Spread throughout. As the liquid adhesive 26 reaches the gap 28, the wafer 10 approaches the flexible sheet 12 and the size of the gap 28 decreases.

  The illustrated sheet sticking method includes a step (FIG. 3A) of solidifying the liquid adhesive 26 and fixing the flexible sheet 12 supported flat on the support surface 14 to the first main surface 16 of the wafer 10. In the embodiment shown in FIG. 3A, a photo-curing adhesive (for example, an ultraviolet-curing adhesive) is used as the liquid adhesive 26 (FIG. 2E), and the rotation of the wafer 10 and the flexible sheet 12 is stopped. By irradiating the liquid adhesive 26 with light (for example, ultraviolet rays) 30 through the wafer 10, the liquid adhesive 26 is solidified. The solidified liquid adhesive 26 becomes an adhesive layer 32 interposed between the first main surface 16 of the wafer 10 and the first surface 20 of the flexible sheet 12. The adhesive layer 32 has rigidity capable of holding the flexible sheet 12 in a flat form against an external force after separating the flexible sheet 12 from the support surface 14.

  Alternatively, when the liquid adhesive 26 made of a photo-curing adhesive is solidified, as shown in FIG. 3B, the liquid adhesive 26 (see FIG. It is also possible to irradiate the liquid adhesive 26 with light (for example, ultraviolet rays) 30 through the wafer 10 while being rotated at a speed slower than the speed for spreading 2E). According to this configuration, the adhesive layer 32 can be formed by solidifying the entire liquid adhesive 26 at a uniform speed.

  In the sheet sticking method having the above configuration, the flexible sheet 12 is flexible with the wafer 10 in a state where at least substantially the entire part to be stuck to the wafer 10 is flatly spread and supported on the flat support surface 14. The liquid adhesive 26 arranged between the sheet 12 is solidified. Even if the curved surface portion is present on the first main surface 16 of the wafer 10 due to the liquid adhesive 26 solidifying while the flexible sheet 12 is flat, the flexible sheet 12 is at least the wafer 10. The first main surface 16 of the wafer 10 is covered in a state in which a flat form is maintained at the portion to be attached to the wafer 10. Therefore, even when the wafer 10 is in a state where the ingot is cut into a thin plate shape, and waviness or warpage is caused due to the cutting operation, the first main surface of the wafer 10 is caused by the adhesive layer 32. The second surface 22 of the flexible sheet 12 fixed to 16 is a flat surface.

  On the other hand, until the liquid adhesive 26 is solidified, the wafer 10 is not substantially deformed and maintains the initial shape. Therefore, when the wafer 10 before the flexible sheet 12 is pasted includes waviness and warpage, the wafer 10 having the flexible sheet 12 pasted on the first main surface 16 through the adhesive layer 32 includes waviness and warpage. It will be. Then, in the subsequent step of the sheet sticking method, the second main surface 18 of the wafer 10 can be ground flat using the flat second surface 22 of the flexible sheet 12 as a reference surface, and further using this ground surface as a reference, The first main surface 16 of the wafer 10 can be ground flat while removing the flexible sheet 12 and the adhesive layer 32.

  In particular, in the above sheet sticking method, the flexible material supported on the support surface 14 in a state where both the first main surface 16 of the wafer 10 and the first surface 20 of the flexible sheet 12 are in contact with the liquid adhesive 26. The sheet 12 is rotated together with the wafer 10 to spread the liquid adhesive 26 in the gap 28 between the first main surface 16 and the first surface 20. By rotating the wafer 10 and the flexible sheet 12, the liquid adhesive 26 spreads quickly and smoothly over the entire gap 28, and generation of voids due to the breakage of the liquid adhesive 26 can be avoided. Further, as in the method described in Patent Document 1 described, in the method in which the liquid adhesive 26 is spread over the gap 28 by pressing the wafer 10 against the flexible sheet 12, internal stress does not remain on the wafer 10. Before the liquid adhesive 26 is solidified, it takes time to automatically restore the wafer 10 to a shape including initial waviness and warpage. Further, by automatically restoring the wafer 10 to the initial shape, there is a concern that the volume of the gap 28 increases, the liquid adhesive 26 is insufficient, the liquid adhesive 26 is locally interrupted, and a gap is generated. On the other hand, in the sheet sticking method, since the wafer 10 is not substantially deformed during the sheet sticking step, the liquid adhesive 26 can be solidified immediately after the liquid adhesive 26 reaches the gap 28. In addition to reducing the time required for the pre-processing performed before processing the wafer 10 into a flat plate, it is possible to prevent the occurrence of voids due to the breakage of the liquid adhesive 26.

  In the sheet sticking method, the support surface 14 desirably has in-plane flatness of 1 μm or less. Here, “in-plane flatness” is defined as the distance between the absolute planes when the support surface 14 is sandwiched between two parallel absolute planes (ie, geometrically correct planes). The support surface 14 having such flatness can be produced by machining from a material such as metal, glass, or ceramics.

  The support surface 14 can be mirror-finished. The support surface 14 that has been subjected to the mirror finish is easily adhered to the second surface 22 of the flexible sheet 12. At this time, the contact state between the support surface 14 and the second surface 22 of the flexible sheet 12 can be improved by dropping or spraying an arbitrary liquid on the support surface 14. Alternatively, the support surface 14 may be formed to be porous, and the second surface 22 of the flexible sheet 12 may be in close contact with the support surface 14 by vacuum suction.

  In the sheet sticking method, when the liquid adhesive 26 made of a photocurable adhesive is solidified, the light 30 is liquefied through the flexible sheet 12 when the wafer 10 is made of a material that does not easily transmit light. The adhesive 26 can also be irradiated. In this case, a flexible sheet 12 made of a transparent resin film can be used. Alternatively, the sheet support 24 can be formed from a light transmissive material such as glass, and the liquid adhesive 26 can be irradiated with light 30 through both the sheet support 24 and the flexible sheet 12.

  In the sheet sticking method, a plurality of positioning members 34 that rotate in synchronization with the support surface 14 can be prepared. In this case, as shown in FIG. 4, during rotation of the sheet support 24, the flexible sheet 12, and the wafer 10 (steps of FIGS. 2D and 2E), at least one of the positioning members 34 is attached to the wafer. The wafer 10 and the flexible sheet 12 can be positioned in a predetermined relative positional relationship by contacting the outer edge 10a of the ten and the outer edge 12a of the flexible sheet 12. This relative positional relationship is predetermined according to the shape and dimensions of the wafer 10 and the flexible sheet 12 so that the flexible sheet 12 can accurately cover the required portion of the first main surface 16 of the wafer 10. It is.

  In the embodiment shown in FIG. 4, a substantially L-shaped positioning member 34 projects from a predetermined position on the outer peripheral portion of the sheet support portion 24 radially outward. As shown in FIG. 5A, the positioning member 34 has an arm portion 36 that extends horizontally from the seat support portion 24, and a columnar contact portion 38 that stands vertically upward at the end of the arm portion 36. The positioning member 34 positions the wafer 10 and the flexible sheet 12 in a predetermined relative positional relationship when the contact portion 38 contacts the outer edges 10 a and 12 a of both the wafer 10 and the flexible sheet 12. .

  In a configuration in which the support surface 14 is larger than the wafer 10 and the flexible sheet 12, a positioning member 34 ′ attached to a predetermined position of the support surface 14 can be used as shown in FIG. 5B. The positioning member 34 ′ includes an arm portion 36 ′ disposed horizontally along the support surface 14, and a plate-like contact portion 38 ′ standing vertically upward at one end of the arm portion 36 ′. The positioning member 34 ′ has a predetermined relative positional relationship between the wafer 10 and the flexible sheet 12 by the contact portion 38 ′ contacting the outer edges 10 a and 12 a of both the wafer 10 and the flexible sheet 12. Position.

  The plurality of positioning members 34 (34 ′) are arranged along the outer edges 10a and 12a of the wafer 10 and the flexible sheet 12 on condition that the wafer 10 and the flexible sheet 12 can be positioned in a predetermined relative positional relationship. Can be distributed at the positions. When the notch 40 that clearly indicates the crystal orientation of the wafer 10 is provided on the outer edge 10a of the wafer 10, as shown in FIGS. 6A and 7A, one of the plurality of positioning members 34 (34 ′) is The contact portion 38 (38 ′) can be disposed at a position where it engages with the notch 40. According to this configuration, torque is applied from one positioning member 34 (34 ′) to the outer edge 10a of the wafer 10 while the sheet support 24, the flexible sheet 12, and the wafer 10 are rotated (step in FIG. 2D). The wafer 10 and the flexible sheet 12 can be rotated in precise synchronization. The flexible sheet 12 can have a cutout portion corresponding to the notch 40 in the outer edge 12a.

  Further, when an orientation flat (orientation flat) 42 that clearly indicates the crystal orientation of the wafer 10 is provided on the outer edge 10a of the wafer 10, as shown in FIGS. 6B and 7B, a plurality of positioning members 34 (34 ′) are provided. Two of them can be arranged at a position where the contact portion 38 (38 ′) engages with the orientation flat 42. According to this configuration, torque is applied from one positioning member 34 (34 ′) to the outer edge 10a of the wafer 10 while the sheet support 24, the flexible sheet 12, and the wafer 10 are rotated (step in FIG. 2D). The wafer 10 and the flexible sheet 12 can be rotated in precise synchronization. The flexible sheet 12 can have a cutout portion corresponding to the orientation flat 42 on the outer edge 12a.

  In the sheet sticking method, the first main surface 16 of the wafer 10 and the flexible sheet 12 are rotated while the sheet support 24, the flexible sheet 12, and the wafer 10 are rotated (steps in FIGS. 2D and 2E). Excess liquid adhesive 26a can be discharged from the gap 28 between the first surface 20 by centrifugal force (FIG. 2E). According to this configuration, the amount of the liquid adhesive 26 used to keep the second surface 22 of the flexible sheet 12 fixed to the first main surface 16 of the wafer 10 through the adhesive layer 32 flat. Can be minimized. Excess liquid adhesive 26 a discharged from the gap 28 can be reused as the liquid adhesive 26 applied to the first main surface 16 of the wafer 10 or the first surface 20 of the flexible sheet 12.

  In the above configuration in which excess liquid adhesive 26a is discharged from the gap 28 by centrifugal force, the contact portion 38 (38 ') of the positioning member 34 (34') described above is formed from the liquid adhesive 26a discharged from the gap 28. It can have a shape that can reduce the impact force it receives. As shown in FIG. 8, the contact portion 38 (38 ′) has a width W orthogonal to the radial direction of the wafer 10 and the flexible sheet 12 (that is, the discharge direction of the liquid adhesive 26a), for example, about 0.5 mm. As described above, the portion facing the outer edges 10a and 12a of the wafer 10 and the flexible sheet 12 can have a pair of outer surfaces 38a having an angle θ of about 60 ° or more and about 120 ° or less. be able to. The intersecting line of these outer surfaces 38a can form a sharp edge as much as possible. However, by chamfering with a radius of curvature of about 0.1 mm, the abutting portion 38 (38 ') can be connected to the wafer 10 and possible. It is possible to prevent the outer edges 10a and 12a of the flexible sheet 12 from being damaged.

  In the sheet sticking method, the first main surface 16 of the wafer 10 and the flexible sheet 12 are rotated while the sheet support 24, the flexible sheet 12, and the wafer 10 are rotated (steps in FIGS. 2D and 2E). As the liquid adhesive 26 spreads through the gap 28 between the first surface 20 and the first surface 20, the first main surface 16 and the first surface 20 can be automatically brought close to each other by gravity. According to this configuration, the liquid adhesive 26 can be surely spread over the entire gap 28, and the generation of voids due to the interruption of the liquid adhesive 26 can be prevented.

  In the above-described configuration in which the first main surface 16 and the first surface 20 are brought close to each other by gravity, all of the positioning members 34 (34 ′) described above are always in contact with the outer edges 10a and 12a of the wafer 10 and the flexible sheet 12. Instead, a certain amount of gap g is formed between the contact portions 38 (38 ') of some positioning members 34 (34') and the outer edges 10a, 12a of the wafer 10 and the flexible sheet 12. Is advantageous (FIG. 8). The gap g corresponds to a tolerance of a predetermined relative positional relationship between the wafer 10 and the flexible sheet 12, and is, for example, about 1 mm or less. Further, by setting the gap g, the operation of inserting the wafer 10 and the flexible sheet 12 into the space between the plurality of positioning members 34 (34 '), and the wafer 10 and the flexible sheet after the adhesive layer 32 is formed. The operation of taking 12 out of the same space becomes easy.

  The liquid adhesive 26 used in the sheet sticking method has an adhesive force for holding the first surface 20 of the flexible sheet 12 firmly fixed to the first main surface 16 of the wafer 10 by curing or solidifying. It can be demonstrated. The material of the liquid adhesive 26 includes (a) a rubber-based adhesive in which rubber, elastomer or the like is dissolved in a solvent, (b) a one-component thermosetting adhesive based on epoxy, urethane, etc., (c) epoxy, Two-component mixed reaction adhesive based on urethane, acrylic, etc. (d) Hot melt adhesive, (e) Ultraviolet or electron beam curable adhesive based on acrylic, epoxy, etc., (f) Water dispersion A mold adhesive or the like can be used. Particularly preferably, an ultraviolet curable adhesive can be used. As the material, at least, (i) an oligomer having a polymerizable vinyl group such as urethane acrylate, epoxy acrylate, or polyester acrylate, and (ii) an acrylic or methacrylic monomer. On the other hand, what added the photoinitiator and the additive as needed can be employ | adopted. Additives include catalysts, accelerators, curing agents, chain transfer agents, viscosity modifiers (eg, containing low viscosity monomers or low viscosity oligomers), thixotropy (eg, containing fused silica), fillers (eg, electrically conductive fillers) , Including heat conductive fillers), plasticizers, dispersants, antifoaming agents, surfactants, flame retardants, heat aging inhibitors, UV aging inhibitors, and the like. Moreover, the viscosity of the liquid adhesive 26 suitable for use in the sheet sticking method can be, for example, about 0.5 Pa · s (about 500 cp) or more and about 5 Pa · s (about 5000 cp) or less. As an example of the ultraviolet curable adhesive, there can be mentioned liquid-ultraviolet curable acrylic liquid adhesive LC-3200 (trade name) available from Sumitomo 3M Limited (Shinagawa-ku, Tokyo).

  9A to 12 schematically show an embodiment of a sheet sticking device according to another aspect of the present disclosure. The illustrated sheet sticking device 50 is a device for sticking a flexible sheet to a wafer, which is a material of a semiconductor element, and can implement the above-described sheet sticking method. In FIG. 9A to FIG. 12, common reference numerals are assigned to components corresponding to the components described in the sheet pasting method, and detailed description thereof is omitted.

  The sheet sticking apparatus 50 includes at least a wafer of a wafer support portion 52 that can support the wafer 10 having the first main surface 16 and the second main surface 18 and the flexible sheet 12 having the first surface 20 and the second surface 22. 10, a sheet support portion (for example, a circular table) 54 having a flat support surface 14 that can support substantially the entire portion to be affixed to 10 with the first surface 20 exposed and attached to the second surface 22, and the wafer 10. Rotation drive units 56 and 58 that respectively rotate the wafer support unit 52 and the sheet support unit 54 in a state where the first main surface 16 and the first surface 20 of the flexible sheet 12 face each other. (FIG. 9A, FIG. 9B).

  The wafer support portion 52 has a support surface 60 that can support the second main surface 18 of the wafer 10 by being fixed by vacuum suction or the like. In the embodiment of FIG. 9A, the wafer support 52 is a support surface 60 that supports a substantially central region of the second major surface 18. The sheet support portion 54 is the support surface 14 and supports at least substantially the entire portion of the flexible sheet 12 attached to the wafer 10 in a flat manner. The sheet support portion 54 and the wafer support portion 52 can be disposed at positions where the former flat support surface 14 and the latter support surface 60 face each other substantially in parallel. In the embodiment of FIG. 9A, the support surface 14 has a slightly smaller dimension than the flexible sheet 12, and supports a portion of the flexible sheet 12 except for the annular region along the outer edge in a flat and tight manner. To do. According to this configuration, excess liquid adhesive 26a (FIG. 9B) discharged from the gap 28 between the first main surface 16 and the first surface 20 during the rotation of the wafer 10 and the flexible sheet 12 is Without coming into contact with the support surface 14, the wafer 10 and the flexible sheet 12 are smoothly scattered outward from the outer edges 10a, 12a.

  The rotation drive unit 56 includes, for example, a servo motor, and rotates the wafer support unit 52 around the axis line 14a at a predetermined speed. The rotation drive unit 58 includes, for example, a servo motor, and rotates the sheet support unit 54 around the axis line 14a at a predetermined speed. The rotation driving units 56 and 58 can rotate the wafer support unit 52 and the sheet support unit 54 in synchronization with each other in accordance with a command. The rotation driving units 56 and 58 rotate the wafer support unit 52 and the sheet support unit 54 synchronously to rotate the sheet support unit 24, the flexible sheet 12, and the wafer 10 in the above-described sheet pasting method. Thus, the step (FIGS. 2D and 2E) of spreading the liquid adhesive 26 in the gap 28 between the first main surface 16 and the first surface 20 can be performed. Further, the rotation driving parts 56 and 58 can hold the wafer support part 52 and the sheet support part 54 at a coaxial position sharing the axis 14a by the centering rotation function inherently possessed by themselves.

  As shown in FIGS. 10A and 10B, the sheet sticking device 50 can include a holding mechanism 62 that holds the wafer support 52 and the sheet support 54 so that they can move in a direction approaching each other in a coaxial state. . In the embodiment shown in FIGS. 10A and 10B, the supporting mechanism 62 can move the wafer support portion 52 having the support surface 60 horizontally and downward in the vertical direction relative to the sheet support portion 54 having the support surface 14 horizontally and upward. To carry. The supporting mechanism 62 includes a main body 66 that supports the wafer support 52 so as to be rotatable around the axis line 14a via a bearing 64, and a linear guide 68 that guides the main body 66 in the vertical direction. When the flexible sheet 12 is rotated together with the wafer 10 (steps of FIGS. 2D and 2E), the holding mechanism 62 is located between the first main surface 16 of the wafer 10 and the first surface 20 of the flexible sheet 12. As the liquid adhesive 26 spreads through the gap 28, the first main surface 16 and the first surface 20 can be brought closer to each other.

  In order to allow the first main surface 16 and the first surface 20 to automatically approach each other by gravity as the liquid adhesive 26 spreads through the gap 28, the support mechanism 62 includes a linear guide 68. The counter balancer 70 can be provided to cancel the weight of the entire movable part that moves in the vertical direction. The counter balancer 70 can be constituted by, for example, a spring, an air cylinder, a counterweight, and the like, and prevents the weight of the entire movable part of the holding mechanism 62 from being applied to the wafer 10 while the liquid adhesive 26 is spread over the gap 28. If the weight of the holding mechanism 62 is not applied to the wafer 10, deformation of the wafer 10 during the sheet sticking process can be prevented.

  In the configuration in which the sheet sticking apparatus 50 includes a holding mechanism 62 that supports the wafer support 52, as shown in FIGS. 10A and 10B, a rotation drive unit (ie, a second rotation drive unit) 56 ( 9A) can be omitted. In this configuration, when the rotation driving unit 58 rotates the sheet support unit 54, the wafer 10 is rotated by the flexible sheet 12 rotating together with the sheet support unit 54 via the liquid adhesive 26. While the wafer 10 rotates following the flexible sheet 12, the wafer 10 is held by the holding mechanism 62 as described above, and the first main surface 16 of the wafer 10, the first surface 20 of the flexible sheet 12, and the like. The liquid adhesive 26 spreads through the gaps 28 therebetween. In the configuration including the supporting mechanism 62 for supporting the wafer support portion 52, the rotation driving portion 56 of the wafer support portion 52 can be provided.

  As shown in FIGS. 10A and 10B, the wafer support 52 can have an O-ring 72 that is arranged to surround the support surface 60. When the wafer 10 has undulations or warpage, there is a concern that the adhesion between the support surface 60 and the second main surface 18 of the wafer 10 may be reduced, but the O-ring 72 undulates the second main surface 18. It is possible to compensate for a decrease in adhesion by elastically deforming along a warp. In particular, in a configuration in which the wafer support unit 52 fixes and supports the wafer 10 on the support surface 60 by vacuum suction, the O-ring 72 is reduced in pressure between the support surface 60 and the second main surface 18 inside. It is elastically deformed and tightly adheres to the second main surface 18. If the O-ring 72 is firmly attached to the second main surface 18, the wafer 10 having waviness and warpage can be stably supported on the support surface 60 even while the wafer support portion 52 rotates at high speed.

  When the photo-curing liquid adhesive 26 is used, as shown in FIG. 11, the sheet sticking device 50 is supported by the first main surface 16 of the wafer 10 supported by the wafer support 52 and the sheet support 54. The light irradiation part 74 which can solidify the liquid adhesive agent 26 which spread to the clearance gap 28 between the 1st surfaces 20 of the flexible sheet | seat 12 can be further provided. By providing the light irradiation unit 74, the flexible adhesive 26 is formed by solidifying the liquid adhesive 26 and forming the adhesive layer 32 on the first main surface 16 of the wafer 10 and supporting the flat surface on the support surface 14 in the above-described sheet pasting method. The step (FIG. 3A) of fixing the adhesive sheet 12 can be performed.

  As shown in FIG. 12, the sheet sticking device 50 can further include a plurality of positioning members 34 that rotate in synchronization with the sheet support portion 54. Each of the positioning members 34 comes into contact with the outer edge 10a of the wafer 10 supported by the wafer support portion 52 and the outer edge 12a of the flexible sheet 12 supported by the sheet support portion 54, and the wafer 10, the flexible sheet 12, and the like. Has a contact portion 38 that can be positioned in a predetermined relative positional relationship (FIG. 5A). In the configuration in which the support surface 14 is larger than the wafer 10 and the flexible sheet 12, a positioning member 34 ′ shown in FIG. 5B can be provided instead of the positioning member 34.

  The positioning member 34 (34 ′) can have a contact portion 38 (38 ′) having a relatively simple shape when the wafer 10 and the flexible sheet 12 have the same or similar shape. When the wafer 10 and the flexible sheet 12 do not have the same or similar shape (for example, when the circular flexible sheet 12 is attached to the wafer 10 having the notches 40 and the orientation flats 42), the wafer 10 and the flexible sheet 12 are acceptable. An abutting portion 38 (38 ') is formed in a shape that can abut against both outer edges 10a, 12a of the flexible sheet 12. In such a case, the wafer 10 is positioned with high accuracy and fixedly supported with respect to the support surface 60 of the wafer support 52 without using the positioning member 34 (34 '), and the sheet support 54 By positioning and supporting the flexible sheet 12 with high precision with respect to the support surface 14, the wafer 10 and the flexible sheet 12 can be positioned in a predetermined relative positional relationship.

  In the configuration in which the sheet sticking device 50 includes a plurality of positioning members 34 (34 '), as shown in FIG. 12, the rotation driving unit 56 (that is, the second rotation driving unit) of the wafer support unit 52 can be omitted. . In this configuration, the rotation driving unit 58 rotates the sheet support unit 54, so that the wafer 10 is dragged to the flexible sheet 12 rotating together with the sheet support unit 54 via the liquid adhesive 26. Here, while the sheet support portion 54 rotates, for example, when the relative positional relationship between the flexible sheet 12 and the wafer 10 is maintained by the action of the liquid adhesive 26, as shown in FIG. 52 can be omitted. In the configuration including the plurality of positioning members 34 (34 ′), the wafer support portion 52 and the rotation driving portion 56 thereof can be provided.

  The sheet sticking apparatus 50 having the above configuration can reduce the time required for the pretreatment performed before the wafer 10 is processed into a flat plate by performing the above-described sheet sticking method. In particular, since the sheet sticking device 50 does not require a structure for pressing the wafer 10 against the flexible sheet 12 and spreading the liquid adhesive 26 to the gap 28, the device configuration is simplified.

  13A to 13C schematically show an embodiment of a wafer processing method according to still another aspect of the present disclosure. The wafer processing method shown in the figure can implement the sheet sticking method described above as the pretreatment. In FIG. 13A to FIG. 13C, constituent elements corresponding to the constituent elements described in the sheet pasting method are denoted by common reference numerals, and detailed description thereof is omitted. 13A and 13B exaggerately show the form in which the wafer 10 includes waviness and warpage.

  As shown in FIG. 13A, by the step (FIG. 3A) of solidifying the liquid adhesive 26 to form the adhesive layer 32 and fixing the flexible sheet 12 to the first main surface 16 of the wafer 10 in the sheet sticking method described above. The obtained laminate is placed and fixed on a work table (not shown). At this time, the flat second surface 22 of the flexible sheet 12 faces the work table, and the second main surface 18 of the wafer 10 is disposed upward. In this state, as shown in FIG. 13B, the second main surface 18 of the wafer 10 is ground using the second surface 22 of the flexible sheet 12 as a reference, and processed into a flat surface 18 a parallel to the second surface 22. To do.

  After processing the second main surface 18 of the wafer 10 into the flat surface 18a, the laminated body is reversed on the work table so that the flat surface 18a of the wafer 10 faces the work table, and the second surface of the flexible sheet 12 is obtained. 22 is placed upward. In this state, the flexible sheet 12 and the adhesive layer 32 are removed from the first main surface 16 of the wafer 10, and the first main surface 16 of the wafer 10 is ground with reference to the flat surface 18a as shown in FIG. 13C. Then, it is processed into a flat surface 16a parallel to the flat surface 18a. In this way, a flat wafer 80 from which undulations and warpage are removed is manufactured.

  According to the wafer processing method having the above configuration, by performing the sheet sticking method described above as a pretreatment, the flat wafer 80 having no residual internal stress can be produced. Can be avoided, and the total time required to process the wafer 10 into the flat wafer 80 can be shortened.

  In order to verify the effectiveness of the wafer processing method described above, the flexible sheet 12 is attached to the wafer 10 under the following conditions (Examples 1 to 3) using the sheet attaching apparatus 50 shown in FIGS. 9A to 12. After that, a flat wafer 80 was manufactured through the procedure of FIGS. 13A to 13C.

[Common conditions]
Wafer 10 ... made of sapphire (diameter 150 mm), ingot cut to 1.5 mm thickness Flexible sheet 12 ... circular PET film (diameter 150 mm), thickness 75 μm
Sheet support base 54 ... Circular table (diameter 150mm)
Support surface 14: In-plane flatness of 1 μm or less Liquid adhesive 26 ... Liquid-UV curable acrylic liquid adhesive LC-3200 (trade name) (Sumitomo 3M Limited (Shinagawa-ku, Tokyo)), viscosity 3 Pa · s (3000 cp), supply amount 5 g
Rotation drive part 58 ... Rotation speed 750rpm, drive time 90 seconds

[Conditions of Example 1]
Device configuration: FIG. 9A
Wafer 10... Warp 118 .mu.m (corresponding to "maximum warpage" described in JIS K6911 (1995) 5.6, the same shall apply hereinafter)
Rotation drive unit 56 ... Rotation speed 750rpm, drive time 90 seconds

[Conditions of Example 2]
Device configuration: FIG. 10A
Wafer 10: Warp 114 μm
Rotation drive unit 56

[Conditions of Example 3]
Device configuration: FIG. 12
Wafer 10: Warp 115 μm
Rotation drive unit 56

The verification results are as follows.
[Example 1]
Wafer 80 ... Warp 7μm
[Example 2]
Wafer 80: Warpage 8 μm
Example 3
Wafer 80: Warpage 8 μm

  Thus, in any of Examples 1 to 3, a flat wafer 80 having extremely small warpage could be produced from the wafer 10 having waviness and warpage through the procedure of FIGS. 13A to 13C.

DESCRIPTION OF SYMBOLS 10 Wafer 10a Outer edge 12 Flexible sheet 12a Outer edge 14 Support surface 16 1st main surface 16a Flat surface 18 2nd main surface 18a Flat surface 20 1st surface 22 2nd surface 24 Sheet support part 26 Liquid adhesive 26a Liquid adhesive 28 Gap 30 Light 32 Adhesive layer 34 Positioning member 36 Arm part 38 Contact part 40 Notch 42 Orientation flat 50 Sheet sticking device 52 Wafer support part 54 Sheet support part 56 Rotation drive part 58 Rotation drive part 60 Support surface 62 Support mechanism 64 Bearing 66 Main unit 68 Linear guide 70 Counter balancer 72 O-ring 74 Light irradiation unit 80 Wafer

Claims (8)

A sheet attaching method for attaching a sheet to a wafer,
Providing a wafer having a first main surface and a second main surface;
Providing a flexible sheet having a shape and dimensions capable of substantially covering the first main surface and having a first surface and a second surface;
Providing a sheet support having a flat support surface;
Attaching the second surface to the support surface with the first surface of the flexible sheet exposed, and supporting the flexible sheet flatly on the support surface;
Applying a liquid adhesive to the first main surface of the wafer or the first surface of the flexible sheet;
Bringing the first main surface of the wafer and the first surface of the flexible sheet opposite to each other and bringing both the first main surface and the first surface into contact with the liquid adhesive;
Rotating the sheet support portion, the flexible sheet, and the wafer to spread the liquid adhesive in a gap between the first main surface and the first surface;
Solidifying the liquid adhesive to fix the flexible sheet to the wafer;
A sheet sticking method including Preparing a plurality of positioning members that rotate in synchronization with the seat support;
While rotating the sheet support portion, the flexible sheet, and the wafer, at least one of the plurality of positioning members is brought into contact with the outer edge of the wafer and the outer edge of the flexible sheet, Positioning the flexible sheet in a predetermined relative positional relationship;
The sheet sticking method according to claim 1, further comprising:   The method according to claim 2, further comprising transmitting torque from at least one of the plurality of positioning members to the outer edge of the wafer while rotating the sheet support portion, the flexible sheet, and the wafer. Sheet affixing method. A sheet sticking device for sticking a sheet to a wafer,
A sheet support portion having a flat support surface capable of supporting a flexible sheet having a first surface and a second surface;
A rotation drive unit that rotates the sheet support unit with the wafer facing the first surface of the flexible sheet;
A sheet sticking apparatus comprising:   A wafer support portion having a support surface capable of supporting the wafer having the first main surface and the second main surface; and the support surface of the sheet support portion and the support surface of the wafer support portion are opposed to each other. The sheet sticking device according to claim 4, which can be arranged.   A second rotation driving unit that rotates the wafer support unit; and the rotation driving unit of the sheet support unit and the rotation driving unit of the wafer support unit include the sheet support unit, the wafer support unit, The sheet sticking device according to claim 5, wherein the sheets are rotated in synchronization with each other.   A plurality of positioning members that rotate in synchronization with the sheet support portion are provided, and each of the positioning members abuts on the outer edge of the wafer and the outer edge of the flexible sheet, and the wafer and the flexible sheet are brought into contact with each other. The sheet sticking device according to any one of claims 4 to 6, further comprising a contact portion that can be positioned in a predetermined relative positional relationship. A wafer processing method including the sheet sticking method according to claim 1,
A wafer processing method comprising: after the step of solidifying the liquid adhesive, grinding the second main surface of the wafer to process it into a flat surface.

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