JP2012119594A - Processing method of plate-like object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method of a plate-like object capable of flattening a plate-like object having irregularities on the surface with high accuracy.
A processing method for a plate-like material in which a back surface of a plate-like material having irregularities on the surface is ground or polished, the first protection comprising a first glue layer and a first substrate on the surface of the plate-like material. After performing a first protective tape adhering step of adhering the tape and absorbing the unevenness with the first adhesive layer, and the first protective tape adhering step, the first protective tape is heated to After performing the first base material removing step of removing the first base material of the protective tape from the first adhesive layer, and the first base material removing step, the first adhesive layer is formed on the first adhesive layer. A second protective tape attaching step of attaching a second protective tape comprising a thinner second adhesive layer and a second base material to alleviate the undulation of the first adhesive layer of the first protective tape; After carrying out the second protective tape attaching step, the second protective tape side of the plate-like object to which the second protective tape is attached is attached to the chuck table. And a processing step of grinding or polishing the back surface of the plate-like material.
[Selection] Figure 8

Description

  The present invention relates to a method for processing a plate-like material in which the back surface of the plate-like material having irregularities on the surface is ground or polished.

  In the manufacturing process of semiconductor devices, division lines called streets are formed in a lattice pattern on the surface of a wafer made of silicon or a compound semiconductor, and devices such as ICs and LSIs are formed in each area partitioned by the division lines. The After the wafer is ground and polished to be thinned to a predetermined thickness, each semiconductor device is manufactured by dividing the wafer along a predetermined division line.

  In order to protect the device formed on the surface of the wafer during grinding or polishing, a protective tape as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-307620 is attached to the surface of the wafer. The wafer is held by a chuck table of a grinding device or a polishing device via a protective tape, and the exposed back surface of the wafer is ground or polished.

  In recent years, as a technology for realizing lighter, thinner, and smaller semiconductor devices, flip chips have been formed by forming a plurality of metal protrusions called bumps on the device surface, and directly bonding these bumps against the electrodes formed on the wiring board. A mounting technique called bonding has been put into practical use.

  However, when a protective tape is attached to a wafer having bumps as high as 200 μm, for example, a gap is formed between the protective tape and the wafer, and the wafer is fixed to the protective tape only by the bumps.

  Therefore, when the back surface of the wafer is ground in this state, there is a problem that stress is applied to the bump portion and the wafer is damaged. In order to solve this problem, for example, Japanese Patent Laid-Open No. 10-50642 discloses a grinding method in which a protective tape having a glue layer thicker than the bump height is attached to the wafer surface for grinding.

JP-A-11-307620 Japanese Patent Laid-Open No. 10-50642

  However, if the gap between the bumps is embedded with glue using a protective tape, irregularities are formed on the surface of the protective tape following the bumps. Even if the back surface of the wafer is ground and polished in this state, there is a problem that it is difficult to flatten the wafer.

  This invention is made | formed in view of such a point, The place made into the objective is providing the processing method of the plate-shaped object which can planarize the plate-shaped object which has an unevenness | corrugation on the surface with high precision. is there.

  According to the present invention, there is provided a processing method for a plate-like object in which the back surface of the plate-like object having irregularities on the surface is ground or polished, the first paste comprising a first glue layer and a first substrate on the surface of the plate-like object. After performing a first protective tape adhering step of adhering a protective tape and absorbing the irregularities with the first adhesive layer, and the first protective tape adhering step, the first protective tape is heated to After performing the first base material removing step of removing the first base material of the first protective tape from the first glue layer, and the first base material removing step, the first glue on the first glue layer. A second protective tape attaching step of attaching a second protective tape composed of a second adhesive layer thinner than the first layer and a second base material to alleviate the undulation of the first adhesive layer of the first protective tape; After performing the second protective tape attaching step, the second protective tape side of the plate-like object to which the second protective tape is attached is chucked. Machining method of the platelet to the processing steps of grinding or polishing the back surface of the platelet held in Le, characterized by comprising a are provided.

  Preferably, the plate-like material processing method of the present invention further includes a coating step of covering the surface of the plate-like material with a water-soluble protective film before the first protective tape attaching step.

  In the processing method of the present invention, a first protective tape is attached to the surface of a plate-like object such as a wafer and the gaps between the bumps are filled with glue, and then the first protective tape is heated to form the first base of the first protective tape. The material is peeled from the first glue layer. Next, the second protective tape is attached on the first adhesive layer of the first protective tape to flatten the surface of the second protective tape.

  By peeling the first base material of the first protective tape from the first adhesive layer and sticking the second protective tape thereon, the undulation caused by the irregularities is absorbed and relaxed by the first and second adhesive layers. Therefore, the surface of the second protective tape can be flattened. Accordingly, when the surface of the second protective tape is sucked and held by the chuck table and the back surface of the plate-like object is ground or polished, the plate-like object can be flattened with high accuracy.

  According to the invention described in claim 2, since the water-soluble protective film is coated on the surface of the plate-like material in advance, the glue of the first protective tape does not directly adhere to the bump, and the first protective tape first No adhesive residue is produced when the glue layer is removed from the plate-like material.

It is a perspective view of a semiconductor wafer suitable for applying the processing method of the present invention. It is an expanded sectional view of the semiconductor wafer shown in FIG. It is sectional drawing of the state which coat | covered the surface of the semiconductor wafer with the water-soluble protective film. It is a partially broken perspective view of a protective film coating apparatus. It is a longitudinal cross-sectional view of the protective film coating apparatus in a state where the spinner table is raised and the wafer is held on the spinner table. It is a longitudinal cross-sectional view of the protective film coating | coated apparatus of the state which apply | coats water-soluble resin to the wafer surface. It is sectional drawing of the state which affixed the 1st protective tape on the surface of the wafer so that a bump might be embedded. It is sectional drawing which shows a mode that the base material of a 1st protective tape is removed from an adhesive layer. It is sectional drawing of the state which stuck the hard 2nd protective tape on the adhesive layer of the 1st protective tape. FIG. 10A is a perspective view showing a grinding step, and FIG. 10B is a side view thereof. It is a longitudinal cross-sectional view of the protective film coating apparatus which shows the washing | cleaning step (protective film removal step).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a perspective view of a semiconductor wafer 11 suitable for processing (grinding) by the processing method of the present invention. The semiconductor wafer 11 has a front surface 11 a and a back surface 11 b, and a plurality of streets 13 are formed orthogonally on the front surface 11 a, and devices 15 are formed in each region partitioned by the streets 13.

  As shown in the enlarged view of FIG. 1, a plurality of protruding bumps 17 are formed on the four sides of each device 15. Since the bumps 17 are formed on the four sides of each device 15, the semiconductor wafer 11 has a bump formation region 19 where the bumps 17 are formed and an outer peripheral bump non-formation region 21 surrounding the bump formation region 19. Yes.

  As shown in the enlarged sectional view of FIG. 2, each bump 17 is connected to the electrode 23 of the device 15. The height of each bump 17 is, for example, 250 μm. In a preferred embodiment of the processing method of the present invention, as shown in FIG. 3, first, a coating step of coating the surface 11a of the wafer 11 with a water-soluble protective film 25 is performed.

  As the liquid resin forming the water-soluble protective film 25, a water-soluble resist such as PVA (polyvinyl alcohol), PEG (polyethylene glycol), PEO (polyethylene oxide) or the like is desirable. In the processing method of the present invention, this water-soluble protective film coating step is not always essential.

  A protective film coating apparatus 10 suitable for performing the protective film coating step will be described with reference to FIGS. First, referring to FIG. 4, a partially broken perspective view of the protective film coating apparatus 10 is shown.

  The protective film coating apparatus 10 includes a spinner table mechanism 12 and a cleaning water receiving mechanism 14 disposed so as to surround the spinner table mechanism 12. The spinner table mechanism 12 includes a spinner table (holding table) 16, an electric motor 20 that rotationally drives the spinner table 16, and a support mechanism 22 that supports the electric motor 20 so as to be movable in the vertical direction.

  The spinner table 16 includes a suction chuck (holding portion) 16a made of a porous material, and the suction chuck 16a communicates with suction means (not shown). Therefore, the spinner table 16 sucks and holds the wafer 11 on the suction chuck 16a by placing the wafer on the suction chuck 16a and applying a negative pressure by suction means (not shown).

  The spinner table 16 is provided with a pair of pendulum type clamps 18. When the spinner table 16 is rotated, the clamps 18 are oscillated by centrifugal force. In the processing method of the present invention, the clamps 18 are used. Since there is no need to do this, the clamp 18 can be omitted.

  The spinner table 16 is connected to the output shaft 20 a of the electric motor 20. The support mechanism 22 includes a plurality of (three in the present embodiment) support legs 24, and a plurality of (three in the present embodiment) air cylinders 26 connected to the support legs 24 and attached to the electric motor 20. It consists of.

  The support mechanism 22 configured in this manner operates the air cylinder 26 to move the electric motor 20 and the spinner table 16 to the wafer loading / unloading position, which is the ascending position shown in FIG. It can be positioned at the working position which is the lowered position shown.

  The cleaning water receiving mechanism 14 is attached to the cleaning water receiving container 28, three support legs 30 (only two are shown in FIG. 4) that support the cleaning water receiving container 28, and the output shaft 20 a of the electric motor 20. Cover member 32.

  As shown in FIG. 5, the washing water receiving container 28 includes a cylindrical outer wall 28a, a bottom wall 28b, and an inner wall 28c. A hole 21 into which the output shaft 20a of the electric motor 20 is inserted is provided at the center of the bottom wall 28b, and the inner wall 28c is formed so as to protrude upward from the periphery of the hole 21.

  As shown in FIG. 4, a waste liquid port 29 is provided on the bottom wall 28 b, and a drain hose 34 is connected to the waste liquid port 29. The cover member 32 is formed in a disc shape, and includes a cover portion 32a protruding downward from the outer peripheral edge.

  When the electric motor 20 and the spinner table 16 are positioned at the work position shown in FIGS. 6 and 10, the cover portion 32 configured in this way is located outside the inner wall 28 c that constitutes the cleaning water receiving container 28. It is positioned so as to be polymerized with a gap.

  The protective film coating apparatus 10 includes an application unit 36 that applies a water-soluble resin to the surface 11 a of the unprocessed wafer 11 held by the spinner table 16. The application unit 36 includes a water-soluble resin supply nozzle 38 that supplies a water-soluble resin toward the surface 11 a of the wafer 11 held by the spinner table 16, and a substantially L-shaped arm 40 that supports the water-soluble resin supply nozzle 38. , And an electric motor 42 capable of normal and reverse rotation that swings the water-soluble resin supply nozzle 38 supported by the arm 40. The water-soluble resin supply nozzle 38 is connected to a water-soluble resin supply source (not shown) via the arm 40.

  The protective film coating apparatus 10 also serves as a cleaning apparatus for the processed wafer 11. Therefore, the protective film coating apparatus 10 includes cleaning water supply means 44 and air supply means 46 for cleaning the processed wafer held on the spinner table 16.

  The cleaning water supply means 44 includes a cleaning water nozzle 48 that ejects cleaning water toward the wafer 11 after processing (after grinding) held by the spinner table 16, an arm 50 that supports the cleaning water nozzle 48, and an arm 50. And an electric motor 52 capable of normal / reverse rotation that swings the washing water nozzle 48 supported by the motor. The cleaning water nozzle 48 is connected to a cleaning water supply source (not shown) via the arm 50.

  The air supply means 46 swings the air nozzle 54 that blows air toward the cleaned wafer 11 held by the spinner table 16, the arm 56 that supports the air nozzle 54, and the air nozzle 54 that is supported by the arm 56. An electric motor (not shown) capable of normal / reverse rotation is provided. The air nozzle 54 is connected to an air supply source (not shown) via an arm 56.

  Next, the operation of the protective film coating apparatus 10 configured as described above will be described. As shown in FIG. 5, the back surface 11b side of the wafer 11 is placed on the spinner table 16 of the protective film coating apparatus 10 positioned at the wafer carry-in / carry-out position, and the wafer 11 is sucked and held by the suction chuck 16a.

  At this time, the water-soluble resin supply nozzle 38, the washing water nozzle 48, and the air nozzle 54 are positioned at a standby position separated from the upper side of the spinner table 16, as shown in FIG. When the wafer 11 is sucked and held by the spinner table 16, the air cylinder 26 is operated to position the spinner table 16 at the work position shown in FIG.

  After the wafer 11 is positioned at the work position in this way, a protective film coating step is performed in which a water-soluble resin is applied to the surface 11a of the wafer 11 to cover the protective film. In order to perform the protective film coating step, the water-soluble resin supply nozzle 38 is formed in the central region of the surface 11a of the wafer 11 while rotating the spinner table 16 at 10 to 100 rpm (preferably 30 to 50 rpm) as shown in FIG. Water-soluble resin 27 is dropped from Reference numeral 60 denotes a lid.

  Since the spinner table 16 is rotated, the dropped water-soluble resin 27 is spin-coated on the surface 11a of the wafer 11, and as shown in FIG. 3, the water-soluble protection is performed so as to wrap the bumps 17 on the surface 11a of the wafer 11. A film 25 is formed. The thickness of the water-soluble protective film 25 is preferably about 5 to 10 μm.

  If the water-soluble protective film 25 is coated on the surface 11a of the wafer 11 by the protective film coating step, as shown in FIG. 7, a first protective tape bonding step of bonding a first protective tape 29 to the surface 11a of the wafer 11. To implement. The first protective tape 29 is configured by disposing an acrylic or rubber paste layer 33 on a base material 31 such as polyolefin.

  The first protective tape 29 has a glue layer 33 having a thickness of, for example, 300 μm, which is thicker than the bumps 17 having a height of 250 μm. In the first protective tape attaching step, the bumps 17 are embedded with the glue layer 33. The first protective tape 29 is attached to the surface 11 a of the wafer 11.

  When the first protective tape 29 having the thick adhesive layer 33 is attached to the surface 11a of the wafer 11 so as to embed the bumps 17 as shown in FIG. 7, the substrate 31 does not become flat. Some swell occurs.

  Therefore, if the first protective tape 29 side is sucked and held by the chuck table of the grinding device and the back surface 11b of the wafer 11 is ground, the wafer 11 may not be flattened with high precision even if the grinding process is performed. is there.

  Therefore, in the processing method of the present invention, as shown in FIG. 8, the base material removing step of heating the first protective tape 29 with the heat lamp 58 and removing the base material 31 of the first protective tape 29 from the adhesive layer 33 is performed. carry out. The heating temperature of the first protective tape 29 by the heat lamp 58 is sufficient, for example, within a range of 50 ° C to 100 ° C.

  By performing the base material removal step, only the glue layer 33 of the first protective tape 29 remains adhered to the water-soluble protective film 25. Next, as shown in FIG. 9, a second protective tape attaching step for attaching the second protective tape 35 on the adhesive layer 33 of the first protective tape 29 is performed. The second protective tape 35 is configured by disposing an acrylic or rubber-based glue layer 39 on a base material 37 that is harder than the base material 31 of the first protective tape such as PET (polyethylene terephthalate).

  When the second protective tape 35 is stuck on the glue layer 33 of the first protective tape 29, the base 31 of the first protective tape 29 is removed from the glue layer 33, so that the undulation caused by the bumps 17 is caused by the glue layer. The base material 37 of the second protective tape 35 can be flattened by being absorbed and relaxed by 33 and 39.

  Therefore, in the embodiment of the present invention, the back surface 11b of the wafer 11 is ground with the first protective tape 29 and the second protective tape 35 from which the base material 31 has been removed adhered to the front surface 11a of the wafer 11. . This grinding method will be described with reference to FIG.

  FIG. 10A is a perspective view of the grinding step, and FIG. 10B is a side view thereof. The grinding unit 62 includes a housing 64, a spindle 65 rotatably accommodated in the housing 64, a motor 66 that rotationally drives the spindle 65, a wheel mount 70 fixed to the tip of the spindle 65, and the wheel mount 70. And a grinding wheel 68 having a plurality of grinding wheels 72 fixed to a lower end surface that is detachably mounted.

  In this grinding step, the wafer 11 is sucked and held by the chuck table 74 of the grinding device through the adhesive layer 33 of the first protective tape 29 and the second protective tape 35. Then, the grinding wheel 72 of the grinding wheel 68 is brought into contact with the back surface 11 b of the wafer 11 by driving the grinding unit feeding mechanism.

  While the grinding wheel 68 is ground and fed at a predetermined grinding feed speed, the chuck table 74 is rotated in the direction of arrow a at 300 rpm, for example, and the grinding wheel 68 is rotated in the direction of arrow b at 6000 rpm, for example, to grind the wafer 11. carry out. While measuring the thickness of the wafer 11 with a contact-type or non-contact-type thickness measurement gauge, the wafer 11 is finished to a predetermined thickness.

  In the present embodiment, the adhesive layer 33 and the second protective tape 35 of the first protective tape 29 are attached to the surface 11a of the wafer 11, and the surface of the second protective tape 35 is flattened before the chuck table 74 of the grinding apparatus. Since the second protective tape 35 is sucked and held, if the back surface 11b of the bumped wafer 11 is ground, the wafer 11 can be flattened with high accuracy.

  After performing the grinding step, the adhesive layer 33 and the second protective tape 35 of the first protective tape 29 are peeled off from the surface 11a of the wafer 11. Since the adhesive layer 33 of the first protective tape 29 is very thick and is adhered to the surface 11a of the wafer 11 so as to embed the bumps 17, when the adhesive layer 33 is peeled off from the wafer 11 after grinding, The glue forming the glue layer 33 embedded between the bumps 17 remains on the water-soluble protective film 25 coated on the surface 11 a of the wafer 11.

  Therefore, in a preferred embodiment of the processing method of the present invention, a protective film removing step of removing the water-soluble protective film 25 by dissolving it in water is performed. This protective film removal step can be performed by the protective film coating apparatus 10 that also serves as a cleaning apparatus.

  That is, as shown in FIG. 11, the back surface 11b side of the wafer 11 is sucked and held by the spinner table 16, and cleaning water composed of pure water and air is ejected from a cleaning water nozzle 48 connected to the pure water source and the air source. While the wafer 11 is rotated at a low speed (for example, 300 rpm), the wafer 11 is cleaned.

  As a result, since the protective film 25 coated on the surface 11a of the wafer 11 is formed of a water-soluble resin, the protective film 25 can be easily washed away, and the remaining adhesive adhered on the protective film 25 The layer 33 can be easily removed.

  In the embodiment described above, an example in which the processing method of the present invention is applied to a grinding method has been described. However, the present invention is not limited to this, and is similarly applied to a polishing method for polishing the back surface of the wafer 11. be able to.

  Further, the workpiece is not limited to the wafer 11 having the bumps 17. For example, the surface of the sapphire substrate other than the outer peripheral portion on the surface of the sapphire substrate, etc. The same applies to plate-like objects.

DESCRIPTION OF SYMBOLS 10 Protective film coating apparatus 11 Semiconductor wafer 15 Device 16 Spinner table 17 Bump 25 Water-soluble protective film 29 1st protective tape 31 Base material 33 Glue layer 35 Second protective tape 37 Base material 39 Glue layer 58 Heat lamp 62 Grinding unit 68 Grinding wheel

Claims (3)

A processing method of a plate-like material for grinding or polishing the back surface of a plate-like material having irregularities on the surface,
A first protective tape attaching step of attaching a first protective tape comprising a first adhesive layer and a first base material to the surface of the plate-like material and absorbing the irregularities with the first adhesive layer;
A first base material removing step of heating the first protective tape and removing the first base material of the first protective tape from the first glue layer after performing the first protective tape attaching step;
After performing the first base material removing step, a second protective tape comprising a second adhesive layer thinner than the first adhesive layer and a second base material is adhered on the first adhesive layer, A second protective tape attaching step for alleviating waviness of the first adhesive layer of the one protective tape;
After performing the second protective tape attaching step, the second protective tape side of the plate-like object to which the second protective tape is attached is held by a chuck table and the back surface of the plate-like object is ground or polished. Processing steps;
The processing method of the plate-shaped object characterized by comprising.   The processing method of the plate-shaped object of Claim 1 further equipped with the coating | coated step which coat | covers the surface of a plate-shaped object with a water-soluble protective film before implementing a said 1st masking tape sticking step.   The plate-like material processing method according to claim 1, wherein the irregularities are constituted by protruding electrodes.

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