JP5762213B2 - Grinding method for plate - Google Patents

Description

  The present invention relates to a method for grinding a plate-like object in which the back surface of a plate-like object such as an optical device wafer is ground and thinned to a predetermined thickness.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. A dividing line is cut by a cutting device (dicing device) to be divided into individual devices, and the divided devices are widely used in electric devices such as mobile phones and personal computers.

  On the other hand, an optical device wafer in which a nitride semiconductor layer such as gallium nitride (GaN) is stacked on the surface and an optical device is formed in each region partitioned by the planned division lines formed in a lattice shape Are divided into individual optical devices by being irradiated with a laser beam, and the divided optical devices are widely used in electronic devices such as mobile phones and digital cameras.

  Since optical device wafers are formed by growing a nitride semiconductor layer on a substrate such as sapphire or silicon carbide (SiC) suitable for the growth of epitaxial layers, these substrates are indispensable materials for manufacturing optical devices. However, after the nitride semiconductor layer is stacked on the substrate, the back surface of the substrate is ground and processed thinly by a grinding device in order to reduce the weight, size, and improve the device characteristics of the electronic device.

  A grinding apparatus for grinding the back surface of a wafer such as a semiconductor wafer or an optical device wafer has a chuck table for holding the wafer and a grinding wheel having a grinding wheel for grinding the wafer held by the chuck table mounted rotatably. A grinding means for grinding the wafer to a desired thickness with high accuracy.

  Usually, when grinding a wafer, a protective tape as disclosed in Japanese Patent Laid-Open No. 5-198542 is attached to protect a device formed on the surface of the wafer. However, if the back surface of the wafer is ground and thinned to, for example, 100 μm or less, the wafer may be warped and the wafer may be damaged during grinding. Alternatively, a thinly ground wafer may be difficult to handle after grinding, and the wafer may be damaged during handling.

  In view of this, a method is adopted in which a wafer is bonded onto a rigid support member as disclosed in Japanese Patent Application Laid-Open No. 2004-207606, and then the back surface of the wafer is ground. Usually, the wafer is stuck on a support member with wax, ultraviolet curable resin or the like.

JP-A-5-198542 JP 2004-207606 A

  After the wafer is attached on the support member made of a rigid body, if the wafer is ground, the wafer can be ground to a very thin thickness without damaging the wafer, but when the wafer thinned by grinding is peeled off from the support member, wax or There was a problem that the wafer was damaged due to the strong adhesion of the UV curable resin.

  The present invention has been made in view of these points, and the object of the present invention is to reduce the possibility of damaging the plate-like material when peeling the plate-like material such as a wafer from the support member. It is to provide a method for grinding a plate-like object.

  According to the present invention, there is provided a method for grinding a plate-like object by grinding the back surface of the plate-like object disposed on the support member to reduce the thickness to a predetermined thickness, and at least one of the support member and the plate-like object. Is formed of a substance that transmits ultraviolet light, and a peeling starting point forming step for forming a peeling starting point part that comes into close contact with a support surface of a supporting member made of a rigid body having an area larger than the area of the plate-like object, and After carrying out the peeling starting part forming step, the surface side of the plate-like material is placed on the peeling starting part via an ultraviolet curable resin that is cured by irradiation with ultraviolet rays and develops softening properties by heating or addition, The ultraviolet curable resin is formed so that the area of the ultraviolet curable resin is larger than the area of the separation starting point and the plate-like material, and the surface side of the plate-like material is embedded in the ultraviolet curable resin, The UV cured tree After the plate-like object placing step to be surrounded by the plate-like object and the plate-like object placing step, the ultraviolet curable resin is irradiated with ultraviolet rays through the support member or the plate-like object, thereby supporting the support. A plate-like object fixing step for fixing the plate-like object with the back surface exposed through the peeling starting portion and the ultraviolet curable resin on the member, and after the plate-like object fixing step is performed, the support member is chucked Holding the table, grinding the back side of the plate-like object, thinning the plate-like object to a predetermined thickness, and after performing the thinning step, the plate-like object is made of the ultraviolet curable resin. After carrying out the support member removing step of peeling the support member from the plate unit in a form integrated with the peel start point portion at the interface between the peel start point portion and the support member, the support member removing step, Heat or hydrate the UV curable resin of the plate unit Is of the grinding method of the platelet, characterized by comprising a an ultraviolet curable resin removal step of removing with 該剥 away the starting portion of the ultraviolet curable resin from the plate-like material is provided.

  Preferably, in the grinding method of the plate-like object, after the thinning step, the adhesive tape is attached to the plate-like object side of the plate-like unit and before the ultraviolet curable resin removing step is performed. A transfer step of attaching the outer peripheral portion to the annular frame is further provided.

  According to the grinding method of the present invention, since the plate-like object is fixed to the support member by the ultraviolet curable resin through the peeling start portion, after the plate-like material is ground, the support member can be easily used with the peeling start portion as the peeling start point. Can be removed.

  The plate-like unit after being separated from the support member has a sufficient strength because the plate-like product and the peeling starting portion are integrated by an ultraviolet curable resin, so that the plate-like product is, for example, 100 μm or less by grinding. Even if processed thinly, the plate-like object is prevented from being damaged when the support member is removed.

  Furthermore, since the ultraviolet curable resin is softened by an external stimulus, the ultraviolet curable resin is softened by applying an external stimulus to the ultraviolet curable resin of the plate unit, and is easily removed from the plate together with the peeling start portion. be able to.

  In addition, by performing the transfer step, the risk of damage to the plate-like material after the UV-curing resin removal step is reduced, and handling of the plate-like material is facilitated.

It is a perspective view which shows a peeling starting part formation step. It is a perspective view which shows an ultraviolet resin supply step. It is a perspective view which shows a mode that an optical device wafer is mounted on the ultraviolet curable resin formed on the support member. It is sectional drawing of the wafer unit after a wafer mounting step, (A) is wafer size> peeling starting part size, (B) is wafer size = peeling starting part size, (C) is wafer size <peeling starting part size. Each is shown. It is sectional drawing which shows a wafer fixing step. 1 is a perspective view of a grinding apparatus suitable for performing a thinning step. It is a partial cross section side view which shows a thinning step. It is sectional drawing which shows a supporting member removal step. It is sectional drawing which shows a transfer step. It is sectional drawing which shows an ultraviolet curable resin removal step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the peeling start point forming step will be described with reference to FIG. In this peeling starting point forming step, the resin film 13 having the coating surface 13a coated with a weak adhesive is attached or placed on the support surface 11a of the support member 11 such as a silicon wafer or glass.

  As the weak adhesive, acrylic glue, rubber glue, or silicone can be used. The resin film 13 is made of polyolefin, polyvinyl chloride, polyethylene terephthalate, or the like.

  When acrylic glue or rubber glue is used as the weak adhesive, the resin film 13 is stuck on the support surface 11a of the support member 11 with the weak adhesive. On the other hand, when silicone is used as the weak pressure-sensitive adhesive, since the silicone does not have a strong adhesive force, the coating surface 13 a of the resin film 13 is in close contact with the support surface 11 a of the support member 11.

  Although both surfaces of the resin film 13 may be coated with a weak adhesive, only one surface is coated and has adhesion to the support surface 11a of the support member 11, while the other surface is not coated. Is more preferable. A thin film of silicone or glue may be formed on the support surface 11 a of the support member 11.

  After the peeling start point forming step is completed, a wafer placing step (plate-like object placing step) is performed. In this wafer mounting step, first, as shown in FIG. 2, an ultraviolet curable resin 17 that is cured by ultraviolet irradiation from the resin supply nozzle 15 and that develops softening properties by heating or addition is supplied onto the resin film 13. The ultraviolet curable resin 17 is preferably a type that does not contain an organic solvent, for example, trade name “TEMPLOC” manufactured by Denki Kagaku Kogyo Co., Ltd.

  Next, as shown in FIG. 3, the optical device wafer 19 having a plurality of optical devices 21 formed on the surface 19 a is placed on the ultraviolet curable resin 17 with the surface 19 a facing down, and the wafer 19 is placed on the support member 11. The UV curable resin 17 is pressed against the wafer until it has an area larger than the wafer size.

  As a result, as shown in FIG. 4 (A), the ultraviolet curable resin 17 is spread so that the area of the ultraviolet curable resin 17 is larger than the areas of the resin film 13 and the wafer 19 as the separation starting point, and the ultraviolet curable resin 17. The surface 19 a of the wafer 19 is embedded in the wafer 19, and the outer periphery of the wafer 19 is surrounded by the ultraviolet curable resin 17. As an alternative embodiment, a sheet-like ultraviolet curable resin having a diameter larger than that of the wafer 19 may be used.

  The size of the resin film 13 acting as a peeling starting point portion needs to be smaller than the size of the support member 11 made of a rigid body, but the size of the wafer 19 is not particularly limited.

  4A shows the case where the size of the wafer 19 is larger than the size of the resin film 13 (the size of the wafer 19> the resin film 13), and FIG. 4B shows the case where the size of the wafer 19 is equal to the size of the resin film 13 ( FIG. 4C shows the case where the size of the resin film 13 is larger than the size of the wafer 19 (size of the wafer 19 <resin film 13).

  When the wafer is formed from a transparent body after the wafer mounting step, the ultraviolet curable resin 17 is irradiated with ultraviolet rays from the ultraviolet lamp 25 via the wafer 19 as shown in FIG. A wafer fixing step of fixing the wafer 19 with the back surface 19b of the wafer 19 exposed through the resin film 13 and the ultraviolet curable resin 17 on the substrate 11 is performed.

  When the optical device wafer 19 is configured by laminating a light emitting layer such as GaN on a sapphire substrate, SiC substrate, or GaN substrate, in the wafer fixing step, ultraviolet rays are applied to the ultraviolet curable resin 17 via the wafer 19 from the wafer back surface 19b side. Irradiate.

  On the other hand, when the wafer is composed of a silicon wafer or a compound semiconductor wafer and is not transparent, the support member 11 is formed of a transparent body made of glass, for example, and the ultraviolet curable resin 17 is irradiated with ultraviolet rays through the support member 11. To.

  After performing the wafer fixing step, a thinning step is performed in which the back surface 19b of the wafer 19 is ground to a predetermined thickness. This thinning step is performed using, for example, a grinding apparatus 2 as shown in FIG. In FIG. 6, 4 is a base of the grinding apparatus 2, and a column 6 is erected on the rear side of the base 4. A pair of guide rails 8 extending in the vertical direction is fixed to the column 6.

  A grinding unit (grinding means) 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The grinding unit 10 includes a spindle housing 12 and a support portion 14 that supports the spindle housing 12. The support portion 14 is attached to a moving base 16 that moves in the vertical direction along a pair of guide rails 8. Yes.

  The grinding unit 10 includes a spindle 18 rotatably accommodated in a spindle housing 12, a motor 20 that rotationally drives the spindle 18, a wheel mount 22 fixed to the tip of the spindle 18, and a detachable attachment to the wheel mount 22. And a mounted grinding wheel 24.

  As shown in FIG. 7, the grinding wheel 24 includes a wheel base 26 that is detachably attached to the wheel mount 22 and a plurality of grinding wheels 28 that are annularly disposed on the outer periphery of the lower end of the wheel base 26. Is done.

  Referring again to FIG. 6, the grinding apparatus 2 includes a grinding unit feed mechanism 34 including a ball screw 30 that moves the grinding unit 10 in the vertical direction along the pair of guide rails 8 and a pulse motor 32. . When the pulse motor 32 is driven, the ball screw 30 rotates and the moving base 16 is moved in the vertical direction.

  A recess 4a is formed on the upper surface of the base 4, and a chuck table mechanism 36 is disposed in the recess 4a. The chuck table mechanism 36 has a chuck table 38 and is moved in the Y-axis direction between a wafer attaching / detaching position A and a grinding position B facing the grinding unit 10 by a moving mechanism (not shown). 40 and 42 are bellows. An operation panel 44 is provided on the front side of the base 4 so that an operator of the grinding apparatus 2 can input grinding conditions and the like.

  Hereinafter, the wafer thinning step performed using the grinding apparatus 2 will be described with reference to FIG. The support member 11 is sucked and held by the chuck table 38 of the grinding device 2, and the back surface 19 b of the wafer 19 is exposed.

  Then, while rotating the chuck table 38 in the direction indicated by arrow a at 300 rpm, for example, the grinding wheel 24 is rotated in the direction indicated by arrow b at, for example, 6000 rpm, and the grinding unit feed mechanism 34 is driven to grind the grinding wheel 24. The grindstone 28 is brought into contact with the back surface 19 b of the wafer 19. Then, the grinding wheel 24 is ground by a predetermined amount at a predetermined grinding feed speed, and the wafer 19 is ground to a predetermined thickness, for example, 100 μm.

  After carrying out the thinning step, a supporting member removing step for removing the supporting member 11 from the wafer unit 23 composed of the integrated wafer 19, the ultraviolet curable resin 17 and the resin film 13 is performed.

  In this support member removing step, for example, as shown in FIG. 8, when a tool such as a scraper is inserted into the interface between the support member 11 and the ultraviolet curable resin 17 along the outer peripheral edge of the wafer unit 23, The support member 11 can be easily peeled off.

  When the support member 11 is peeled from the wafer unit 23, the resin film 13 in which the coating surface 13a acting as a peeling start point portion is coated with a weak adhesive serves as a peeling start point, and the support member 11 can be easily removed from the wafer unit 23. Can be peeled off.

  Since the thinned wafer 19 has rigidity by integrating the ultraviolet curable resin 17 and the resin film 13, there is almost no risk of wafer breakage when the support member 11 is peeled off or during handling after peeling.

  After the support member removing step is performed, as shown in FIG. 9, a transfer step is performed in which the adhesive tape T is adhered to the back surface 19 b side of the wafer 19 and the outer peripheral portion of the adhesive tape T is adhered to the annular frame F. This transfer step may be performed before the support member removing step. In this case, a support member removing step is performed after the transfer step.

  After the transfer step, as shown in FIG. 10A, the ultraviolet curable resin 17 is softened by heating the ultraviolet curable resin 17 with a heating lamp 27. As shown in FIG. 10B, when the ultraviolet curable resin 17 is pulled in the direction of arrow P, the ultraviolet curable resin 17 is softened, so that the ultraviolet curable resin 17 together with the resin film 13 acting as a peeling start point is formed. It is easily peeled off from the wafer 19.

  The heating of the ultraviolet curable resin 17 is not limited to the heating lamp 27, but hot air is blown on the ultraviolet curable resin 17 or the ultraviolet curable resin 17 is placed on a hot plate and heated. Also good.

  Further, the ultraviolet curable resin 17 is not limited to softening by heating, and the ultraviolet curable resin 17 may be swelled and separated from the wafer 19 by being immersed in hot water.

  After performing the UV curable resin removal step, dicing using a cutting device, or grooving + expanding process using a laser processing apparatus, or forming a modified layer + expanding process, the optical device wafer 19 is individually separated. The optical device 21 is divided.

  The wafer is preliminarily formed with a modified layer or grooving, and after the UV curable resin removal step shown in FIG. 10, the adhesive tape T is expanded to divide the optical device wafer 19 into individual optical devices 21. You may make it do.

  Alternatively, after the thinning step, the wafer 19 is subjected to a modified layer forming process or a grooving process, and after the ultraviolet curable resin removing step shown in FIG. 10, the adhesive tape T is expanded to make the optical device wafer 19 an individual optical device 21. You may make it divide | segment. In this case, since the rigidity of the wafer 19 is reduced by the modified layer or the grooving groove, the grinding method of the present invention is particularly effective.

(Experiment 1)
Adhere the following peeling starting point on the following support member, then apply UV curable resin on the peeling starting point and place the sapphire wafer, press the sapphire wafer with a precision press and attach it to the supporting member It was. Thereafter, the ultraviolet curable resin was irradiated with ultraviolet rays through a sapphire wafer to fix the sapphire wafer on the support member. When the sapphire wafer was ground to 80 μm, the presence or absence of cracks in the wafer and whether or not the support member could be peeled were confirmed, and the results shown in Table 1 were obtained.

Support member: Quartz glass with φ8 inch, 1 mm thickness Peeling origin: Weak adhesive coated PET film with thickness of 50 μm Workpiece: Sapphire wafer with φ6 inch, thickness 1 mm

  As is apparent from Table 1, in the case where there was no peeling start point, it was impossible to peel the support member 11 from the wafer unit 23, but when the peeling start point was formed, the size of the peeling start point and the wafer size The support member 11 could be peeled from the wafer unit 23 regardless of the size.

DESCRIPTION OF SYMBOLS 11 Support member 13 Resin film 17 coated with soft adhesive agent 19 UV curable resin 19 Optical device wafer 21 Optical device 23 Wafer unit 24 Grinding wheel 25 Ultraviolet lamp 28 Grinding wheel T Adhesive tape F Annular frame

Claims (3)

A method for grinding a plate-like object by grinding a back surface of a plate-like object disposed on a support member to reduce the thickness to a predetermined thickness, wherein at least one of the support member and the plate-like object transmits ultraviolet rays. Composed of substances,
A peeling starting point forming step for forming a peeling starting point portion that adheres to the supporting surface of the supporting member made of a rigid body having an area larger than the area of the plate-like material in a peelable manner;
After carrying out the peeling starting part forming step, the surface side of the plate-like material is placed on the peeling starting part via an ultraviolet curable resin that is cured by irradiation with ultraviolet rays and develops softening properties by heating or addition, The ultraviolet curable resin is formed so that the area of the ultraviolet curable resin is larger than the area of the separation starting point and the plate-like material, and the surface side of the plate-like material is embedded in the ultraviolet curable resin, A plate-like object placing step that is surrounded by the ultraviolet curable resin,
After carrying out the plate-like object placing step, the ultraviolet curable resin is irradiated with ultraviolet rays through the support member or the plate-like substance, and the separation starting point portion and the ultraviolet curable resin are passed through the support member. A plate fixing step for fixing the plate with the back surface exposed;
After carrying out the plate-like object fixing step, the supporting member is held by a chuck table, the back side of the plate-like object is ground, and the thinning step of thinning the plate-like object to a predetermined thickness;
After carrying out the thinning step, the support member is removed from the plate unit in a form in which the plate-like material is integrated with the peeling starting portion with the ultraviolet curable resin at the interface between the peeling starting portion and the supporting member. A supporting member removing step for peeling;
After carrying out the supporting member removing step, the ultraviolet curable resin of the plate unit is heated or hydrolyzed and softened, and the ultraviolet curable resin is removed from the plate together with the peeling starting portion. When,
A plate-like object grinding method comprising:   After carrying out the thinning step and before carrying out the UV curable resin removal step, stick an adhesive tape on the plate-like object side of the plate-like object unit and affix the outer periphery of the adhesive tape to an annular frame. The plate-like object grinding method according to claim 1, further comprising a transfer step of attaching.   The plate-like object is made of sapphire or SiC, the support member is made of a silicon wafer, and in the plate-like object fixing step, the ultraviolet curable resin is irradiated with ultraviolet rays from the plate-like object side. A method for grinding plate-like objects.

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