KR20080003994A - Dicing films and dicing tapes for laser sawing - Google Patents

Abstract

A polyolefin-based dicing film for laser sawing is provided to prevent generation of pick-up errors caused by the heat from laser beams leading to melting of a dicing film or damages on a dicing film. A polyolefin-based dicing film(50) has a transmission of 80-99% and a reflectance of 1-20% to the light having a wavelength of 355 nm. The polyolefin includes polyethylene, polypropylene, polytetrafluoroethylene, polymethylpentene, or polyvinyl acetate. Preferably, the polyolefin includes a polypropylene having a weight average molecular weight of 200,000-1,500,000, or a blend containing a low-density polyethylene having a weight average molecular weight of 100,000-2,000,000 and ethylene vinyl acetate having a weight average molecular weight of 50,000-1,500,000 in a weight ratio of 30:70-65:35.

Description

Dicing films and dicing tapes for laser sawing}

1A is a side cross-sectional view showing a state before laser sawing a wafer having a dicing tape attached thereto.

FIG. 1B is a side cross-sectional view illustrating a dicing tape of FIG. 1A according to an embodiment of the present invention in which the dicing tape is ideally cut by laser sawing. FIG.

FIG. 1C is a side cross-sectional view showing a state according to the prior art in which the dicing tape of FIG. 1A is cut by laser sawing. FIG.

FIG. 2A is an optical micrograph of a dicing film surface photographed after laser sawing using a dicing film according to Example 1 of the present invention. FIG.

FIG. 2B is an optical microscope photograph of the dicing film surface after the laser sawing is performed using the dicing film of Comparative Example 1. FIG.

<Explanation of symbols for the main parts of the drawings>

10: wafer 20: adhesive

30: dicing film 40: laser source

50: dicing tape

The present invention relates to a laser sawing dicing film and a dicing tape, and more particularly, to a laser sawing dicing film and a dicing tape which can prevent pickup misses.

BACKGROUND OF THE INVENTION In the manufacture of semiconductor devices, a plurality of circuits are formed on a wafer substrate, and each of them is cut and diced (dicing) into a piece of device. In more detail, the method for manufacturing the device fragments is attached by attaching an adhesive sheet to the wafer substrate, dicing the substrate using a blade, and then separating the adhesive tape by inflating the adhesive tape in the longitudinal direction or picking up the element fragments.

In addition, when the individual semiconductor elements separated into small pieces are attached to the lead frame, bonded and molded, they are sawed and separated by using a blade or the like to separate each individual package.

In recent years, the method of dicing a semiconductor substrate or a semiconductor package by sawing of the laser beam which has little thermal damage and can be processed with high precision has attracted attention as a precise cutting method.

At this time, a dicing tape or a direct film adhesive (DFA) is used on the back surface of the wafer or the back of the lead frame. The die pick-up or package pick-up characteristics are different after laser dicing depending on the type and physical properties of the dicing tape. This difference is largely due to the difference in UV absorbance coefficients when irradiated with UV laser light. When the UV absorbance is high, an object such as a silicon wafer is easily diced, but the dicing tape is easily damaged.

If the pressure-sensitive adhesive or dicing film melts due to the heat of the laser beam and enters the interface with the semiconductor wafer or flows into the groove formed by the damage of the dicing film (locking phenomenon, see FIG. 1C A), the device is picked up later. There is a problem that an error occurs.

Therefore, there is a need for a dicing film that is hardly damaged by a laser beam.

The first technical problem to be achieved by the present invention is to provide a dicing film that can prevent pickup failure.

The second technical problem to be achieved by the present invention is to provide a dicing tape that can prevent pickup failure.

The present invention provides a polyolefin-based dicing film, characterized in that the transmittance for the light having a wavelength of 355 nm, and the reflectance is 1% to 20% to achieve the first technical problem.

In order to achieve the second technical problem, the present invention provides a polyolefin-based dicing film having a transmittance of 80% to 99% for a light having a wavelength of 355 nm and a reflectance of 1% to 20%, and a surface of the dicing film. Provided are a dicing tape containing an applied adhesive.

In the following, the present invention is described in more detail.

An ideal dicing figure is shown conceptually in FIGS. 1A and 1B. Referring to FIG. 1A, the back surface of the wafer 10 is fixed to the dicing film 30 to which the pressure-sensitive adhesive 20 is applied. When an ideal singulation is achieved by the laser source 40, the dicing film 30 is separated without being damaged as shown in Fig. 1B. That is, the wafer 10 and the pressure-sensitive adhesive 20 are cut by the laser beam radiated from the laser source 40, and the laser beam is sufficiently transmitted or reflected with respect to the dicing film 30 to the dicing film 30. Since the amount absorbed is small, the dicing film 30 is not damaged.

However, if the laser beam is not sufficiently transmitted or reflected on the dicing film 30, the laser beam is excessively absorbed by the dicing film 30, which leads to damage of the dicing film 30. Then, the locking phenomenon as described above occurs.

A first aspect of the present invention provides a polyolefin-based dicing film, characterized in that the transmittance for light having a wavelength of 355 nm is 80% to 99%, the reflectance is 1% to 20%. The transmittance is more preferably 85% to 99%, still more preferably 90% to 99%. The reflectance is more preferably 5% to 20%, even more preferably 8% to 20%.

The transmittance of the light is multiplied by 100 after dividing the intensity of the transmitted light by the intensity of the incident light, and the reflectance is given by the ratio of the energy of the reflected light and the energy of the incident light.

If the transmittance of the dicing film is less than 80%, it is not preferable because the amount of light absorbed by the dicing film is too large and easily damaged. Moreover, the film whose transmittance | permeability of the said dicing film exceeds 99% is difficult to manufacture.

In addition, if the reflectance of the dicing film is less than 1%, it is not preferable because the amount of light absorbed by the dicing film is too large and easily damaged. In addition, a dicing film having a reflectance of more than 20% is difficult to manufacture.

The transmittance and reflectance can be measured using, for example, a model such as UV-VIS Spectrophotometer LAMBDA950, manufactured by PERKIN-ELMER, but is not limited thereto.

The dicing film may be any film as long as it is a film providing the transmittance and reflectance as described above, and is not particularly limited. The dicing film may be, for example, a polyolefin resin, more specifically, polyethylene, polypropylene, polytetrafluoroethylene, polymethylpentene, polyvinylacetate, or a mixture thereof. Can be, but is not limited to this.

According to a preferred embodiment, the dicing film is a mixture of LDPE resin having a weight average molecular weight of 100,000 to 2,000,000 and EVA (ethyl vinyl acetate) resin having a weight average molecular weight of 50,000 to 1,500,000 in a weight ratio of 30:70 to 65:35 It may be, but is not limited to this.

Optionally, the dicing film may be, but is not limited to, polypropylene or a blend mixture thereof having a weight average molecular weight of 200,000 to 1,500,000.

According to a second aspect of the present invention, a polyolefin-based dicing film having a transmittance of 80% to 99% for light having a wavelength of 355 nm and a reflectance of 1% to 20%, and an adhesive applied to one surface of the dicing film It provides a dicing tape containing. The transmittance is more preferably 85% to 99%, still more preferably 90% to 99%. The reflectance is more preferably 5% to 20%, even more preferably 8% to 20%.

The polyolefin-based dicing film may be a polyolefin-based dicing film according to the first aspect of the present invention.

The said adhesive can use a well-known adhesive. For example, although adhesives, such as rubber type, an acryl type, silicone type, and polyvinyl ether, can be used, it is not limited to this. Optionally, a photopolymerizable compound may be used as the main component in the acrylic pressure-sensitive adhesive. As the photopolymerizable compound, for example, a low molecular compound having at least two or more photopolymerizable carbon-carbon double bonds in a molecule capable of forming a three-dimensional network by light irradiation may be used. Examples of such low molecular weight compounds include, but are not limited to, trimethylol propane triacrylate, urethane acrylate, polyethylene glycol diacrylate, and the like.

Moreover, the said adhesive may be an epoxy resin. The epoxy resin may be, for example, glycidyl naphthalene, diglycidyl naphthalene, triglycidyl naphthalene, tetraglycidyl naphthalene, dicyclopentadiene oxide resin, and the like. It is not.

The method of forming the layer by applying the pressure-sensitive adhesive on the polyolefin-based dicing film may be, for example, by a method such as bar coating, reverse coating, dip coating, solution casting, but is not limited thereto.

Hereinafter, the structure and effects of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.

<Example 1>

A film was prepared by mixing a LDPE resin having a weight average molecular weight of 140,000 and an EVA resin having a weight average molecular weight of 87,000 at a weight ratio of 35:65.

As a result of measuring the transmittance of the prepared film was 84%, the result of measuring the reflectance was 13%, and an adhesive was applied to prepare an adhesive tape. The adhesive was a blend of an epoxy resin and an acrylic resin. After attaching the wafer to the adhesive tape, sawing was performed using a laser beam of 355 nm wavelength and a pickup experiment was performed 100 times.

As a result, it was confirmed that no pickup miss occurred.

Comparative Example 1

A film was prepared by mixing an LDPE resin having a weight average molecular weight of 85,000 and an EVA resin having a weight average molecular weight of 40,000 at a weight ratio of 40:60.

As a result of measuring the transmittance of the prepared film was 78%, the result of measuring the reflectance was 3%, an adhesive was applied to prepare an adhesive tape. The adhesive was a blend of an epoxy resin and an acrylic resin. After attaching the wafer to the adhesive tape, sawing was performed using a laser beam of 355 nm wavelength and a pickup experiment was performed 100 times.

As a result, it was confirmed that 22 pickup misses occurred.

<Example 2>

A film was prepared by mixing an LDPE resin having a weight average molecular weight of 1,780,000 and an EVA resin having a weight average molecular weight of 1,320,000 at a weight ratio of 40:60.

As a result of measuring the transmittance of the prepared film was 97%, the reflectance was measured 2%, the pressure-sensitive adhesive was applied to prepare an adhesive tape. The same adhesive as that used in Example 1 was used. After attaching the wafer to the adhesive tape, sawing was performed using a laser beam of 355 nm wavelength and a pickup experiment was performed 100 times.

As a result, it was confirmed that no pickup miss occurred.

Comparative Example 2

A film was prepared by mixing an LDPE resin having a weight average molecular weight of 550,000 and an EVA resin having a weight average molecular weight of 1,550,000 at a weight ratio of 70:30.

As a result of measuring the transmittance of the prepared film was 73%, the result of measuring the reflectance was 5%, an adhesive was applied to prepare an adhesive tape. The adhesive was a blend of an epoxy resin and an acrylic resin. After attaching the wafer to the adhesive tape, sawing was performed using a laser beam of 355 nm wavelength and a pickup experiment was performed 100 times.

As a result, it was confirmed that 29 pickup misses occurred.

Comparative Example 3

A film was prepared by mixing an LDPE resin having a weight average molecular weight of 1,080,000 and an EVA resin having a weight average molecular weight of 1,700,000 at a weight ratio of 70:30.

As a result of measuring the transmittance of the prepared film was 75%, and as a result of measuring the reflectance was 4%, an adhesive was applied to prepare an adhesive tape. The same adhesive as that used in Example 1 was used. After attaching the wafer to the adhesive tape, sawing was performed using a laser beam of 355 nm wavelength and a pickup experiment was performed 100 times.

As a result, it was confirmed that 26 pickup misses occurred.

The surface of the dicing film after dicing in Example 1 and Comparative Example 1 was photographed using an optical microscope and the results are shown in FIGS. 2A and 2B, respectively.

As shown in the photograph, Figure 2b showing Comparative Example 1 is a sawing trace is strongly revealed, but Figure 2a showing Example 1 can be seen that the sawing trace is insignificant (in the water droplet form of Figure 2a is an adhesive residue).

Although described in detail with respect to preferred embodiments of the present invention as described above, those of ordinary skill in the art, without departing from the spirit and scope of the invention as defined in the appended claims Various modifications may be made to the invention. Therefore, changes in the future embodiments of the present invention will not depart from the technology of the present invention.

When the dicing tape is manufactured using the dicing film of the present invention and the wafer and / or the package is separated using the dicing tape, pick-up failure can be prevented.

Claims (9)

A polyolefin-based dicing film, characterized in that the transmittance for light having a wavelength of 355 nm is 80% to 99%, the reflectance is 1% to 20%. The polyolefin-based dicing film according to claim 1, wherein the polyolefin is polyethylene, polypropylene, polytetrafluoroethylene, polymethylpentene, or polyvinylacetate. The polyolefin-based dicing film according to claim 1, wherein the transmittance is 85% to 99% and the reflectance is 5% to 20%. The polyolefin-based dicing film according to claim 1, wherein the transmittance is 90% to 99% and the reflectance is 8% to 20%. The method of claim 1, wherein the polyolefin is a polypropylene having a weight average molecular weight of 200,000 to 1,500,000; Or a mixture of low density polyethylene having a weight average molecular weight of 100,000 to 2,000,000 and ethyl vinyl acetate having a weight average molecular weight of 50,000 to 1,500,000 at a weight ratio of 30:70 to 65:35. A dicing tape comprising a polyolefin dicing film having a transmittance of 80% to 99% for light having a wavelength of 355 nm and a reflectance of 1% to 20%, and an adhesive applied to one surface of the dicing film. The polyolefin-based dicing tape according to claim 6, wherein the polyolefin is polyethylene, polypropylene, polytetrafluoroethylene, polymethylpentene, or polyvinylacetate. 7. The polyolefin-based dicing tape according to claim 6, wherein the transmittance is 85% to 99% and the reflectance is 5% to 20%. 7. The polyolefin-based dicing tape according to claim 6, wherein the transmittance is 90% to 99% and the reflectance is 8% to 20%.

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