JP5193752B2 - Laser dicing sheet and semiconductor chip manufacturing method - Google Patents

Description

  The present invention relates to a laser dicing sheet that is preferably used for fixing a semiconductor wafer when a semiconductor chip is formed by dividing a semiconductor wafer into individual circuits by laser light irradiation. The present invention also relates to a method for manufacturing a semiconductor chip using the dicing sheet. In particular, the laser dicing sheet of the present invention is preferably used when a chip is manufactured by fixing and cutting a semiconductor wafer having a circuit formed on the front surface and an annular convex portion on the outer periphery of the back surface.

  After a circuit is formed on the surface of the semiconductor wafer, grinding is performed on the back side of the wafer, and a back grinding process for adjusting the thickness of the wafer and a dicing process for dividing the wafer into a predetermined chip size are performed. Further, following the back surface grinding step, there may be a processing that involves heat generation such as an etching process on the back surface, or a process that is performed at a high temperature such as vapor deposition of a metal film on the back surface.

  With the spread of IC cards in recent years, the semiconductor chip that is a constituent member thereof is being made thinner. For this reason, it has been required to reduce the thickness of a conventional wafer having a thickness of about 350 μm to 50 to 100 μm or less.

  As the wafer that is a brittle member becomes thinner, the risk of breakage increases during processing and transportation. For this reason, when grinding a wafer to an extremely thin thickness or transporting an extremely thin wafer, the wafer must be fixed and protected on a hard plate such as a glass plate or an acrylic plate with a double-sided adhesive sheet. Yes.

  However, in the method of laminating the wafer and the hard plate with the double-sided pressure-sensitive adhesive sheet, the wafer may be broken when the both are peeled after the series of steps is finished. When peeling a laminate formed by bonding two thin-layer products, it is necessary to bend one or both of the thin-layer products and to peel them off. However, since it is impossible or difficult to curve the hard plate, the wafer side must be curved. For this reason, a fragile wafer may break.

  In addition, it is not appropriate to fix the wafer with a double-sided pressure-sensitive adhesive sheet or the like when performing processing at a high temperature on the back surface of the wafer after the back surface grinding as described above. That is, when the wafer is exposed to a high temperature with the wafer held on the hard plate via the double-sided pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet softens and decomposes, and the wafer holding function is lost. In addition, the double-sided pressure-sensitive adhesive sheet may shrink or expand due to heat, and the ultrathin wafer may be deformed. Further, the wafer may be contaminated by a decomposition product of organic matter derived from the double-sided pressure-sensitive adhesive sheet.

  For this reason, as shown in FIGS. 2 to 4, at the time of back surface grinding, the entire back surface of the wafer is not ground smoothly, but only the back surface inner peripheral portion 16 is ground, and the annular convex portion 17 remains on the back surface outer peripheral portion. (Patent Documents 1, 2, etc.). As shown in FIG. 2, the wafer surface has a surplus portion 15 in which a circuit 13 is not formed within a range of several mm from the outer peripheral edge, and the circuit 13 is formed on the wafer inner peripheral portion 14 excluding the surplus portion. Yes. In the back surface grinding method, only the back surface inner peripheral portion 16 corresponding to the front surface circuit forming portion (wafer inner peripheral portion 14) is ground to a predetermined thickness, and the back surface region corresponding to the surplus portion 15 where no circuit is formed. Remains without grinding. As a result, an annular convex portion 17 is formed on the outer peripheral portion of the back surface of the semiconductor wafer after grinding. Since the annular protrusion 17 has relatively high rigidity, the wafer ground in the above-described form can be stably conveyed and stored without using a hard plate. Therefore, according to the wafer ground in the above form, it is not necessary to use a double-sided pressure-sensitive adhesive sheet or the like for fixing the hard plate, so that the wafer can be stably held even when the back surface processing is performed by exposure to high temperature. In addition, the wafer is not contaminated by decomposition products of organic matter.

On the other hand, dicing of a wafer is usually performed using a rotating round blade (blade), but recently, dicing using a laser beam (laser dicing) has been proposed. Laser dicing is attracting attention because it may be able to cut even a wafer that is difficult to cut by blade dicing. Various laser dicing sheets used for such laser dicing have been proposed (Patent Document 3).
JP 2007-59829 A JP 2008-34708 A JP 2006-245487 A

  When dicing a semiconductor wafer with laser light, the entire back surface of the wafer is fixed with a laser dicing sheet, and the outer periphery of the dicing sheet is fixed with a ring frame. Thereafter, dicing is performed by irradiating a laser beam along the street between the circuits while recognizing the circuit pattern from the wafer surface side. As a result, the generated chip is held on the dicing sheet, and then the chip is picked up by a predetermined means.

  However, when only the inner peripheral portion of the back surface of the wafer is ground as described above and the annular convex portion is left on the outer peripheral portion, the generated chip 12 is diced in the wafer dicing step as shown in FIG. The chip 12 may be dropped or scattered without being held on the sheet 20. That is, when only the back inner peripheral portion 16 of the wafer is ground and the annular convex portion 17 remains on the outer peripheral portion, the step between the inner peripheral plane and the annular convex portion is about 100 to 700 μm. For this reason, in the vicinity of the annular convex part, the dicing sheet 20 may have air bubbles and may not adhere to the inner peripheral part plane. If the wafer is diced in this state, the chips 12 cut in the vicinity of the annular convex portion 17 are not held on the dicing sheet 20, and the chips 12 fall off or scatter. As a result, the yield of the chips is reduced, and the dicing apparatus may be damaged by the scattered chips.

  Therefore, in the present invention, only the back inner peripheral portion of the wafer is ground, the outer peripheral portion has an annular convex portion, and the wafer rear surface in which a step is formed between the inner peripheral plane and the annular convex portion, An object of the present invention is to provide a laser dicing sheet that can be adhered and adhered with good followability and that can securely hold a wafer and a chip during laser dicing.

The gist of the present invention aimed at solving such problems is as follows.
(1) It consists of a single-layer or multi-layer base material and an adhesive layer formed on one side thereof,
The total light transmittance at 300 to 400 nm of at least one layer of the substrate is 40% or more,
A laser dicing sheet in which the product of the square of the thickness of the base material and the Young's modulus of the base material is 0.3 to 6.5 N.
(2) A step of affixing the laser dicing sheet according to (1) on the back surface of a semiconductor wafer having a circuit formed on the front surface and having an annular convex portion on the back surface outer peripheral portion;
A method of manufacturing a semiconductor chip, comprising a step of irradiating a semiconductor wafer with a laser beam and dividing the semiconductor wafer into individual circuits to create a semiconductor chip.
(3) A step of affixing the laser dicing sheet according to (1) on the back surface of a semiconductor wafer having a circuit formed on the front surface and having an annular convex portion on the back surface outer peripheral portion;
A step of irradiating a semiconductor wafer with a laser beam and separating the semiconductor wafer into pieces for each circuit to create a semiconductor chip;
A method of manufacturing a semiconductor chip, comprising expanding a laser dicing sheet to expand a chip interval.

  According to the present invention, only the back inner peripheral portion of the wafer is ground, the outer peripheral portion has an annular convex portion, and the wafer rear surface in which a step is formed between the inner peripheral portion plane and the annular convex portion, Provided is a laser dicing sheet that can be adhered and adhered with good followability and can securely hold a wafer and a chip during laser dicing.

  Hereinafter, preferred embodiments of the present invention will be described more specifically with reference to the drawings, including the best mode.

  As shown in FIG. 1, a laser dicing sheet 10 according to the present invention includes a base material 1 and an adhesive layer 2 formed on one surface thereof. In addition, in FIG. 1, the base material 1 consists of two layers of the base material layers 1a and 1b.

  The total light transmittance at 300 to 400 nm of at least one layer of the substrate 1 is 40% or more, preferably 40 to 100%, more preferably 45 to 98%.

  Furthermore, the product of the square of the thickness of the substrate 1 and the Young's modulus is 0.3 to 6.5 N, preferably 0.35 to 6.3 N, and more preferably 0.4 to 6.0 N.

  By setting the total light transmittance of 300 to 400 nm of at least one layer of the substrate 1 within the above range, the transmittance of laser light, particularly a short wavelength laser (for example, wavelength 355 nm) is improved. As a result, the sheet is less damaged by the laser beam, and the sheet 10 is not cut during laser dicing. On the other hand, when the total light transmittance at 300 to 400 nm of the substrate 1 is less than 40%, the sheet is greatly damaged by the laser beam, and the sheet 10 is cut during laser dicing. In addition, in FIG. 1, although the base material 1 of 2 layers is shown, the base material 1 may be a single layer (1 layer), and may be a multilayer (2 layers or more). In the case of a single layer, the total light transmittance of the substrate 1 may be in the above range, and in the case of a multilayer, the total light transmittance of at least one layer of the substrate 1 may be in the above range. The one layer is less damaged by the laser beam and the sheet 10 is not cut.

  In addition, by making the product of the square of the thickness of the substrate 1 and the Young's modulus within the above range, the shape following property of the laser dicing sheet can be increased, and for example, to an adherend having a step of about 675 μm Also, the laser dicing sheet can be stuck and pasted. On the other hand, when the product of the square of the thickness of the substrate 1 and the Young's modulus is larger than 6.5, the shape following property of the laser dicing sheet is low, and air (bubbles) is trapped between the sheet and the wafer. It becomes difficult to hold the wafer. Moreover, when the product of the square of the thickness of the base material 1 and the Young's modulus is smaller than 0.3, the base material 1 is too thin or too soft, so that it does not have support and does not function as a laser dicing sheet. That is, it is difficult to manufacture a semiconductor chip. In addition, since the adhesive layer 2 is flexible, its thickness or the like does not greatly affect the followability of the sheet.

Here, the thickness of the substrate 1 is expressed in mm, and the Young's modulus of the substrate 1 is expressed in MPa (= N / mm ² ). Therefore, the product of the square of the thickness of the substrate 1 and the Young's modulus is N (Newton) units.

  Although the thickness of the base material 1 is not restrict | limited at all, Preferably it is 0.03-0.2 mm, More preferably, it is 0.04-0.15 mm, Most preferably, it exists in the range of 0.05-0.13 mm. The Young's modulus of the substrate 1 is preferably in the range of 80 to 1200 MPa, more preferably 100 to 1000 MPa. The substrate 1 in the dicing sheet 10 of the present invention is appropriately selected so that the product of the square of the thickness of the substrate 1 and the Young's modulus falls within the above range in consideration of the thickness and Young's modulus. For example, in the case of polyethylene and polypropylene having crystallinity, the Young's modulus is increased by adding a nucleating agent to increase the crystallinity, increasing the density, or adding an alicyclic material. can do. For other materials, the Young's modulus can be controlled by adjusting the crosslinking density.

  Therefore, when using a material with a relatively high Young's modulus, the thickness of the base material is reduced. When using a material with a low Young's modulus, the thickness of the base material is increased. A substrate to be obtained is obtained.

  The thickness of the pressure-sensitive adhesive layer 2 is preferably in the range of 0.001 to 0.3 mm, more preferably 0.003 to 0.15 mm, and particularly preferably 0.005 to 0.05 mm. If the thickness of the pressure-sensitive adhesive layer 2 is too thin, sufficient adhesive strength may not be obtained. On the other hand, when the thickness of the pressure-sensitive adhesive layer 2 is too thick, the wafer may vibrate when the wafer 11 is diced to cause chipping or cause adhesive residue.

  Moreover, when the thickness of the laser dicing sheet 10 is extremely thin, if the sheet is damaged by the laser light, the sheet 10 may be cut and the holding function of the chip 12 may be significantly impaired. Even if the sheet 10 is not cut, a groove is cut on the surface of the sheet 10. If the depth of the groove is too deep with respect to the thickness of the sheet 10, the strength of the sheet 10 is reduced, and the expandability of the sheet 10 is impaired. The laser dicing sheet 10 may be expanded after the laser dicing process in order to extend the chip interval. However, when a deep groove is formed on the surface of the sheet 10 by cutting into the laser dicing sheet, the laser dicing sheet 10 is broken starting from the groove and cannot be expanded.

  For this reason, when applying the laser dicing sheet 10 of this invention to the manufacturing method of the chip | tip including an expanding process, the sum total of the thickness of the base material 1 and the thickness of the adhesive layer 2 becomes like this. The thickness is 0.5 mm, more preferably 0.043 to 0.3 mm, and particularly preferably 0.055 to 0.18 mm.

  The material of the substrate 1 used in the dicing sheet 10 of the present invention is not particularly limited as long as the above physical properties are satisfied. For example, a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a high density polyethylene ( HDPE) film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyurethane film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) An acrylic ester copolymer film and a film made of a water additive or a modified product thereof are used. These crosslinked films are also used. The above-mentioned base material may be one kind alone, or may be a composite film in which two or more kinds are combined.

  As will be described later, when the pressure-sensitive adhesive layer 2 is formed of an ultraviolet curable pressure-sensitive adhesive and ultraviolet rays are used as energy rays to be irradiated to cure the pressure-sensitive adhesive, a substrate that is transparent to the ultraviolet rays is used. preferable. In addition, since it does not need to be transparent when using an electron beam as an energy beam, the transparent film which colored these other than said film, an opaque film, etc. can be used.

  Moreover, in order to improve adhesiveness with an adhesive, the upper surface of the base material 1, ie, the base material surface on the side where the adhesive layer 2 is provided, may be subjected to corona treatment or a primer layer. Various coatings may be applied to the surface opposite to the pressure-sensitive adhesive layer 2. The dicing sheet 10 according to the present invention is manufactured by providing a pressure-sensitive adhesive layer on the substrate as described above.

  In the case where the pressure-sensitive adhesive layer 2 is formed of an ultraviolet curable pressure-sensitive adhesive and ultraviolet rays are used as the energy rays to be irradiated to cure the pressure-sensitive adhesive, the fragrance such as a benzene ring is included in the structure of the film used for the substrate 1. It is preferable not to include a ring. Since the aromatic ring absorbs ultraviolet rays, the substrate 1 is easily cut by laser light.

  The pressure-sensitive adhesive layer 2 can be formed of various conventionally known pressure-sensitive adhesives. Such an adhesive is not limited at all, but an adhesive such as rubber-based, acrylic-based, silicone-based, or polyvinyl ether is used. In addition, an energy ray curable adhesive, a heat-foaming adhesive, or a water swelling adhesive can be used. As the energy ray curable (ultraviolet ray curable, electron beam curable) pressure-sensitive adhesive, it is particularly preferable to use an ultraviolet curable pressure-sensitive adhesive. The pressure-sensitive adhesive layer 2 may be laminated with a release sheet to protect the pressure-sensitive adhesive layer before use.

  The release sheet is not particularly limited. For example, a film made of a resin such as polyethylene terephthalate, polypropylene, or polyethylene or a foamed film thereof, paper such as glassine paper, coated paper, laminated paper, silicone-based, fluorine A system and a release agent such as a long chain alkyl group-containing carbamate can be used.

  The method of providing the pressure-sensitive adhesive layer 2 on the surface of the substrate may be such that the pressure-sensitive adhesive layer applied and formed on the release sheet so as to have a predetermined film thickness may be transferred to the surface of the substrate, or directly applied to the surface of the substrate. Then, the pressure-sensitive adhesive layer may be formed.

  Next, a method for manufacturing a semiconductor chip using the laser dicing sheet 10 of the present invention will be described.

  In the present invention, first, a semiconductor wafer 11 having a circuit 13 formed on the front surface and an annular convex portion 17 on the outer periphery of the back surface is prepared. 2 is a plan view of the circuit side of the semiconductor wafer, FIG. 3 is a perspective view from the back side, and FIG. 4 is a cross-sectional view of FIG.

  The semiconductor wafer 11 may be a silicon wafer or a compound semiconductor wafer such as gallium / arsenic. The formation of the circuit 13 on the wafer surface can be performed by various methods including conventionally used methods such as an etching method and a lift-off method. In the circuit forming process of the semiconductor wafer, a predetermined circuit 13 is formed. The circuit 13 is formed in a lattice shape on the surface of the inner peripheral portion 14 of the wafer 11, and a surplus portion 15 in which no circuit is present remains in a range of several mm from the outer peripheral end. The thickness of the wafer 11 before grinding is not particularly limited, but is usually about 500 to 1000 μm.

  At the time of back grinding, an adhesive sheet called a surface protective sheet is attached to the circuit surface in order to protect the circuit 13 on the surface. In the back surface grinding, the circuit surface side (that is, the surface protection sheet side) of the wafer 11 is fixed by a chuck table or the like, and the back surface side where the circuit 13 is not formed is ground by a grinder. At the time of back surface grinding, first, the entire back surface is ground to a predetermined thickness, and then only the back surface inner peripheral portion 16 corresponding to the circuit forming portion (inner peripheral portion 14) on the front surface is ground, and the surplus portion 15 where the circuit 13 is not formed. The back surface area corresponding to is left without being ground. As a result, in the semiconductor wafer 11 after grinding, only the back inner peripheral portion 16 is further thinly ground, and the annular convex portion 17 remains on the outer peripheral portion. Such a back grinding method can be performed by a known method described in Patent Documents 1 and 2, for example. After the back surface grinding process, a process of removing the crushed layer generated on the ground surface by grinding may be performed. Although the thickness of the wafer 11 after grinding is not particularly limited, the annular convex portion 17 is usually about 300 to 725 μm, and the back inner peripheral portion 16 is about 25 to 200 μm.

  Subsequent to the back grinding step, if necessary, the back surface may be subjected to processing that generates heat such as an etching process, or processing performed at a high temperature such as vapor deposition of a metal film or baking of an organic film on the back surface. In addition, when processing at high temperature, after peeling a surface protection sheet, the process to a back surface is performed.

  According to the wafer 11 in which only the back inner peripheral portion 16 is ground to a predetermined thickness and the outer peripheral portion has the annular convex portion 17, the rigidity of the annular convex portion 17 is high, so that it is stable without using a hard plate. Can be transported and stored. Therefore, according to the wafer 11 ground in the above-described form, it is not necessary to use a double-sided adhesive sheet or the like. Therefore, the wafer 11 can be stably held even when the back surface processing is performed by exposure to high temperature. 11 is not contaminated by the decomposition product of organic matter.

  After the back surface grinding step, as shown in FIG. 5, the laser dicing sheet 10 of the present invention is attached to the grinding surface side of the wafer 11, and the wafer 11 is diced. In addition, the surface protection sheet stuck on the surface may be peeled off before the laser dicing sheet 10 is stuck, or may be peeled off after the laser dicing sheet 10 is stuck.

  The laser dicing sheet 10 is attached to the back surface of the wafer by an apparatus called a mounter, but is not particularly limited. The pressure-sensitive adhesive layer 2 of the laser dicing sheet 10 is flexible and has excellent shape followability. Further, the peripheral portion of the laser dicing sheet 10 is fixed by the ring frame 5.

  Next, the wafer 11 is irradiated with laser light, and the wafer 11 is diced. The laser light source 3 is a device that generates light having a uniform wavelength and phase, and is a solid laser such as YAG (basic wavelength = 1064 nm) or ruby (fundamental wavelength = 694 nm), or an argon ion laser (fundamental wavelength = 1930 nm). In the present invention, a laser beam having a short wavelength with a high energy density is particularly preferably used in order to fully cut the wafer. As such a short wavelength laser, a third harmonic (wavelength = 355 nm) of an Nd-YAG laser is particularly preferably used. The intensity and illuminance of the laser light depend on the thickness of the wafer to be cut, but it is sufficient that the wafer can be fully cut.

  The laser beam is irradiated onto the streets between the circuits of the wafer 11 to chip the wafer for each circuit. The number of times the laser beam scans one street may be one time or multiple times. Preferably, the irradiation position of the laser beam and the position of the street between the circuits are monitored and the wafer 11 is irradiated with the laser beam while aligning the laser beam.

  Since the base material 1 of the laser dicing sheet 10 of the present invention satisfies the specific physical properties as described above, the base material 1 is not cut by a laser beam and has excellent shape followability to the adherend surface. Therefore, only the back surface inner peripheral portion 16 of the wafer is ground, the outer peripheral portion has the annular convex portion 17, and the followability to the wafer rear surface in which a step is formed between the inner peripheral portion plane and the annular convex portion. Can be adhered and adhered, and the wafer and the chip 12 can be securely held during dicing. Further, during laser dicing, the disk-shaped plate 4 having an outer diameter slightly smaller than the inner diameter of the annular convex portion 17 is applied after the dicing sheet 10 is adhered in order to prevent the wafer inner peripheral portion from sagging and to keep the wafer surface flat. May be fitted into a region surrounded by the annular protrusion 17.

  According to the laser dicing sheet 10 of the present invention, since the wafer and the chip can be securely held during dicing, the yield of the chips can be improved, and the dicing apparatus can be prevented from being damaged due to scattering of the chips.

  After the dicing is completed, the chip 12 is picked up from the laser dicing sheet 10. In the case where the pressure-sensitive adhesive layer 2 of the laser dicing sheet 10 is formed of an ultraviolet curable pressure-sensitive adhesive, the chip 12 is picked up after the pressure-sensitive adhesive layer 2 is irradiated with ultraviolet rays to reduce the adhesive strength before the pickup. .

  When the laser dicing sheet 10 is expanded prior to the pickup, the chip interval is expanded, and the chip can be picked up more easily. However, when a deep groove is cut into the surface of the laser dicing sheet 10 by laser light irradiation, the strength of the laser dicing sheet 10 is reduced and the expandability of the laser dicing sheet 10 is impaired. For this reason, when applying the laser dicing sheet 10 of the present invention to a chip manufacturing method including the step of expanding the laser dicing sheet 10, the sum of the thickness of the substrate 1 and the thickness of the pressure-sensitive adhesive layer 2 is: It is desirable to be in the above range.

  When the chip is picked up without expanding, the sum of the thickness of the substrate 1 and the thickness of the pressure-sensitive adhesive layer 2 is not necessarily in the above range.

  Further, after the dicing is completed, the chip group aligned on the laser dicing sheet 10 may be transferred to another pressure-sensitive adhesive sheet for pickup, and then the expansion and chip pickup may be performed.

  Thereafter, the picked-up chip 12 is die-bonded and resin-sealed by a conventional method to manufacture a semiconductor device.

  The example of use of the laser dicing sheet 10 of the present invention has been described above by taking, as an example, laser dicing of a semiconductor wafer formed with an annular convex portion. However, the laser dicing sheet 10 of the present invention is an ordinary flat semiconductor wafer. It can be used for dicing (dividing) various articles such as glass substrates, ceramic substrates, organic material substrates such as FPC, or metal materials such as precision parts.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, the following base materials were used.

  Moreover, in the Example and the comparative example, the following was used for the adhesive layer of the laser dicing sheet.

[Adhesive layer]
A polyvalent isocyanate compound (Coronate L) was added to a 30% by weight toluene solution of a copolymer (weight average molecular weight 650,000) consisting of 80 parts by weight of butyl acrylate, 10 parts by weight of methyl methacrylate and 10 parts by weight of 2-hydroxyethyl acrylate. (Nippon Polyurethane Co., Ltd.)) The pressure-sensitive adhesive composition obtained by mixing 2.5 parts by weight on a PET film (SP-PET3811 manufactured by Lintec Co., Ltd.) subjected to silicone release treatment has a dry film pressure of 10 μm. And dried (100 ° C., 1 minute), and the adhesive was laminated on a predetermined surface of the substrate shown in Table 1 by transfer to obtain a dicing sheet.

  A silicon wafer having the following shape was affixed to the obtained dicing sheet so that the annular convex portion side was opposed to the pressure-sensitive adhesive layer surface.

  The evaluation method of the laser dicing conditions, the total light transmittance of the laser dicing sheet, and the Young's modulus of the substrate is shown below.

  Moreover, the following method evaluated the dicing sheet followable | trackability using the obtained laser dicing sheet, the cutting depth, and the expand appropriateness. The results are shown in Table 2.

[Laser dicing conditions]
-Equipment: Nd-YAG laser-Wavelength: 355 nm (third harmonic)
・ Output: 5.5W
・ Repetition frequency: 10 kHz
・ Number of times of irradiation: 2 times / 1 line ・ Cut speed: 200 mm / sec
・ Laser focus: Wafer grinding surface ・ Wafer material: Silicon ・ Wafer inner peripheral thickness: 50 μm (annular convex thickness: 725 μm)
・ Wafer size: 200 mm (inner diameter of annular projection: 198 mm)
・ Cut chip size: 5mm x 5mm

[Total light transmittance]
From the sheet | seat base material side, the total light transmittance measurement (UV-VIS, measurement wavelength: 300-400 nm) was performed using Shimadzu UV-3101PC. Among the values obtained, the lowest value is listed in the table.

[Young's modulus]
The Young's modulus of the substrate was measured at a tensile speed of 200 mm / min (sample size: 100 mm × 15 mm) using a universal tensile tester (Tensilon RTA-T-2M manufactured by Orientec Co., Ltd.) in accordance with JIS K7161.

[Base material thickness]
The thickness of the base material was measured using a constant pressure thickness meter (PG-02 manufactured by TECLOCK).

[Dicing sheet followability]
The length of the bubbles observed at the step between the annular convex portion and the inner peripheral portion of the wafer was measured using a digital microscope. A case where bubbles having an average value (average width) in the wafer diameter direction of 1.3 mm or more were observed was defined as “defective”.

[Incision depth evaluation]
After laser dicing was completed, the cut line was cross-sectionally observed, and the depth of cut from the surface of the sheet including the adhesive layer was measured (the observation site was a portion where the wafer was not applied and the laser was directly irradiated). What has been cut is indicated as “cut”.

[Expandability]
After the laser dicing was completed, the dicing sheet to which the wafer was attached was expanded (drawn 10 mm) with an expanding device. A case where expansion was impossible was defined as “bad”.

  The dicing sheets of Examples 1 to 6 showed good followability, could be used without any problem even in the laser dicing process, and the expandability was also good.

  When the product of the square of the thickness of the substrate and the Young's modulus exceeds 6.5 (Comparative Examples 2 to 5, 8 to 10), the followability is not sufficient, and the wafer and the chip are laser dicing sheets during laser dicing. It was difficult to hold it securely. The product of the square of the thickness of the substrate and the Young's modulus is in the range of 0.3 to 6.5, but the total light transmittance is less than 40% (Comparative Examples 1-3, 6, 7). In this case, the sheet was cut, and the chip holding function was significantly impaired.

Sectional drawing of the dicing sheet of this invention is shown. The top view of the circuit formation surface of a semiconductor wafer is shown. The perspective view of the semiconductor wafer in which the annular convex part was formed in the back peripheral part is shown. FIG. 4 shows a cross-sectional view of FIG. 3. The outline of one process of the chip manufacturing method concerning the present invention is shown. The outline of one process of the chip manufacturing method using the conventional dicing sheet is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Adhesive layer 3 ... Laser light source 4 ... Disc shaped plate 5 ... Ring frame 10 ... Dicing sheet 11 ... Semiconductor wafer 12 ... Semiconductor chip 13 ... Circuit 14 ... Circuit surface inner peripheral part 15 ... Surplus part 16 ... Back inner peripheral part 17 ... annular convex part 20 ... conventional dicing sheet

Claims (4)

It consists of a single-layer or multi-layer base material, and an adhesive layer formed on one side,
The total light transmittance at 300 to 400 nm of at least one layer of the substrate is 40% or more,
The product of the square and the substrate Young's modulus of the thickness of the substrate is Ri 0.3~6.5N der,
A laser dicing sheet that is affixed to the back surface of a semiconductor wafer having a circuit formed on the front surface and an annular convex portion on the back outer peripheral portion . The laser dicing sheet according to claim 1, wherein the total light transmittance at 300 to 400 nm of at least one layer of the substrate is 90 to 98%. A step of attaching the laser dicing sheet according to claim 1 or 2 to the back surface of a semiconductor wafer having a circuit formed on the front surface and having an annular convex portion on the outer periphery of the back surface;
A method of manufacturing a semiconductor chip, comprising a step of irradiating a semiconductor wafer with a laser beam and dividing the semiconductor wafer into individual circuits to create a semiconductor chip. A step of attaching the laser dicing sheet according to claim 1 or 2 to the back surface of a semiconductor wafer having a circuit formed on the front surface and having an annular convex portion on the outer periphery of the back surface;
A step of irradiating a semiconductor wafer with a laser beam and separating the semiconductor wafer into pieces for each circuit to create a semiconductor chip;
A method of manufacturing a semiconductor chip, comprising expanding a laser dicing sheet to expand a chip interval.

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