Composite sheet for protective film formation

Abstract

The present invention is a composite sheet for forming a protective film, comprising a support sheet and a protective film for forming a protective film disposed on one side of the support sheet, wherein the protective film for forming a protective film has a transmittance of less than 0.3% for light with a wavelength of 365nm.

Description

[Technical Field] This invention relates to a composite sheet for forming a protective film. This application claims priority based on Japanese Patent Application No. 2019-086700, filed on April 26, 2019, the contents of which are incorporated herein by reference. [Previous Technology] In the manufacturing process of semiconductor devices, protective films are sometimes used to protect the workpieces that need to be processed to obtain the target object. For example, when manufacturing semiconductor devices using a packaging method called flip-chip, a semiconductor wafer with electrodes such as bumps on the circuit surface is used as the workpiece. To prevent cracking of the semiconductor wafer or the semiconductor wafer that serves as a cleavage of the semiconductor wafer, a protective film is sometimes used to protect the inner surface of the semiconductor wafer or semiconductor wafer that is opposite to the circuit surface. In addition, in the manufacturing process of semiconductor devices, a semiconductor device panel (described later) is used as the workpiece. To prevent warping or cracking of the panel, a protective film is sometimes used to protect any part of the panel. To form such a protective film, a protective film forming composite sheet is used, for example, which includes a support sheet and a protective film forming film for forming the protective film on one side of the support sheet. The protective film forming film can function as a protective film by curing or in an uncured state. Furthermore, the support sheet can be used to fix a workpiece having the protective film forming film or a cured version of the protective film forming film. For example, when using a semiconductor wafer as a workpiece, the support sheet can be used as a dicing sheet required for dividing the semiconductor wafer into semiconductor wafers. Examples of support sheets include: a support sheet having a substrate and an adhesive layer disposed on one side of the substrate; and a support sheet consisting only of a substrate. When the support sheet has an adhesive layer, the adhesive layer is disposed between the substrate and the protective film forming film in the protective film forming composite sheet. When using the aforementioned protective film forming composite sheet, firstly, the protective film forming film of the protective film forming composite sheet is attached to the target area of ​​the workpiece. Then, the workpiece having the protective film forming composite sheet is processed as needed to obtain a processed workpiece. For example, when using a semiconductor wafer as the workpiece, after the protective film forming composite sheet is attached to the inner surface of the workpiece via the protective film forming film, the following operations are appropriately performed at suitable times: forming a protective film by hardening the protective film forming film, cutting the protective film forming film or the protective film, dicing (cutting) the semiconductor wafer into semiconductor wafers, and picking up semiconductor wafers with the cut protective film forming film or the protective film on their inner surface from the support sheet (semiconductor wafers with or without a protective film forming film). In the case of picking up a semiconductor wafer with a protective film forming film, the semiconductor wafer with the protective film forming film is formed by curing the protective film forming film, and finally, the semiconductor wafer with the protective film forming film is used to manufacture a semiconductor device. Furthermore, at any stage up to obtaining the target semiconductor device, sometimes laser printing is performed by irradiating the side of the protective film forming film or the cured protective film forming film opposite to the attachment surface of the workpiece or workpiece (i.e., the support sheet side of the protective film forming composite) with laser light. This printing is used, for example, to identify a workpiece or workpiece having a protective film. Regarding the printing applied to the protective film forming film, the same state is maintained after the protective film is formed by curing the film; therefore, laser printing can be performed at any stage of the protective film forming film and the cured protective film forming film. Patent Document 1 discloses an inner protective film for protecting the inner surface of a semiconductor device with a parallel light transmittance of 15% or more at a wavelength of 800 nm. Patent Document 2 discloses a composite sheet for forming a protective film with a total light transmittance of 3% or more at a wavelength of 555 nm. [Prior Art Documents][Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 2016-213244. [Patent Document 2] Japanese Patent Application Publication No. 2016-213243. [Summary of the Invention] [The problem that the invention aims to solve] As a composite sheet for forming such a protective film, in addition to a composite sheet for forming a protective film that utilizes a support sheet having an adhesive layer that hardens by heating, a support sheet that utilizes an adhesive layer that hardens by irradiation with energy lines such as ultraviolet light is also used. On the other hand, if an energy line is irradiated onto a semiconductor wafer or a semiconductor wafer with a protective film, there is a risk of damage to the semiconductor wafer or malfunction. This risk is even higher, especially when using an adhesive that hardens with energy lines on a semiconductor wafer with a protective film, where irradiation with energy lines is necessary. Furthermore, in recent years, semiconductor wafers have become increasingly thinner, and in order to prevent semiconductor wafer breakage, they must be easily picked up from the support sheet. In addition, if visible light passes through the protective film forming film, grinding marks on the semiconductor wafer can sometimes be seen, impairing the design. Additionally, if the laser markings applied to the inner surface of the semiconductor wafer for process management, which are not required at the time of shipment, can be seen through the protective film or protective film, then the information of the laser markings applied to the inner surface of the semiconductor wafer may overlap with the laser markings on the surface of the protective film, causing poor readability. Patent Document 1 does not disclose the following protective film forming composite sheet: to improve the transmittance of parallel light at a wavelength of 800nm ​​by using an infrared camera to detect cracks in the semiconductor wafer through the inner protective film, thus protecting the semiconductor wafer from energy line interference; and to enable easy pick-up of the semiconductor wafer from the support sheet without damage. Furthermore, Patent Document 2 does not disclose the following protective film forming composite sheet: to detect gaps in the semiconductor wafer when attaching the protective film forming composite sheet to the semiconductor wafer, thus improving the transmittance of total light at a wavelength of 555nm and protecting the semiconductor wafer from energy lines; and to enable easy pick-up of the semiconductor wafer from the support sheet without damage. The present invention aims to provide a composite sheet for forming a protective film, comprising a support sheet and a protective film for forming a protective film disposed on one side of the support sheet, wherein even when an energy line is irradiated onto a semiconductor wafer or a semiconductor wafer with a protective film, there is no damage to the semiconductor wafer or malfunction. Furthermore, the present invention aims to provide a composite sheet for forming a protective film that allows for easy picking up of a semiconductor wafer from the support sheet without damaging the semiconductor wafer. Moreover, the present invention aims to provide a composite sheet for forming a protective film that exhibits excellent design by suppressing visible grinding marks on the inner surface of the wafer or laser markings implemented for process management, and has a low probability of causing poor reading of laser markings on the surface of the protective film. [Means for solving the problem] The present invention provides a composite sheet for forming a protective film, comprising a support sheet and a protective film for forming disposed on one side of the support sheet, wherein the protective film for forming has a transmittance of less than 0.3% for light with a wavelength of 365nm. The composite sheet for forming the protective film of the present invention preferably comprises a support sheet having a substrate and an adhesive layer disposed on one side of the substrate, wherein the adhesive layer is disposed between the substrate and the protective film forming film, and the adhesive layer is an energy line curing adhesive layer. In the composite sheet for forming the protective film of the present invention, preferably, the transmittance of the protective film forming film for light with a wavelength of 555 nm is 5% or less. In the composite sheet for forming the protective film of the present invention, preferably, the transmittance of the protective film forming film for light with a wavelength of 800 nm is less than 20%. [Effects of the Invention] This invention provides a composite sheet for forming a protective film, comprising a support sheet and a protective film for forming a protective film disposed on one side of the support sheet. Even when an energy line is irradiated onto a semiconductor wafer or a semiconductor wafer with a protective film, there is no risk of damage to the semiconductor wafer or malfunction. Furthermore, this invention provides a composite sheet for forming a protective film, comprising a support sheet and a protective film for forming a protective film disposed on one side of the support sheet. When picking up a semiconductor wafer from the support sheet, the semiconductor wafer can be easily picked up without damage. Moreover, this invention provides a composite sheet for forming a protective film that exhibits excellent design by suppressing visible grinding marks on the inner surface of the wafer or laser markings implemented for process management, and has a low probability of causing poor reading of laser markings on the protective film surface.

Implementation Method

Claims

1. A composite sheet for forming a protective film, comprising a support sheet and a protective film for forming disposed on one side of the support sheet; the protective film for forming is only thermosetting; the support sheet comprises a substrate and an adhesive layer disposed on one side of the substrate; the protective film for forming has a transmittance of 0.3% or less for light with a wavelength of 365 nm; and the protective film for forming has a transmittance of 5% or less for light with a wavelength of 555 nm.

2. The composite sheet for forming a protective film as described in claim 1, wherein the aforementioned adhesive layer is disposed between the aforementioned substrate and the aforementioned protective film forming film; the aforementioned adhesive layer is an energy-line curable adhesive layer.

3. The composite sheet for forming a protective film as described in claim 1, wherein the adhesion between the aforementioned protective film forming film or the hardened portion of the aforementioned protective film forming film and the aforementioned support sheet does not reach 370mN / 25mm.

4. The composite sheet for forming a protective film as described in claim 1, wherein the transmittance of the aforementioned protective film for light with a wavelength of 800 nm is less than 20%.

5. The composite sheet for forming a protective film as described in claim 2, wherein the transmittance of the aforementioned protective film for light with a wavelength of 800 nm is less than 20%.

6. The composite sheet for forming a protective film as described in claim 3, wherein the transmittance of the aforementioned protective film for light with a wavelength of 800 nm is less than 20%.

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