KR-20260065778-A - PROTECTIVE FILM AGENT FOR LASER DICING, METHOD OF MANUFACTURING PROTECTIVE FILM AGENT FOR LASER DICING AND METHOD OF PROCESSING WORKPIECE USING PROTECTIVE FILM AGENT FOR LASER DICING

Abstract

(Problem) When a protective film containing a UV absorber is stored for a long period, the functions of the UV absorber, such as UV absorption and luminescence characteristics, deteriorate over time. For example, under light exposure conditions, high temperature conditions, or alkaline conditions, there is a problem that the function of the UV absorber deteriorates in a relatively short period. Therefore, the objective is to provide a protective film for laser dicing in which the function of the protective film containing a UV absorber does not deteriorate significantly over time compared to conventional protective films. (Solution) According to one embodiment of the present invention, a protective film for laser dicing is provided, comprising a solution in which a water-soluble resin, an organic solvent, and a UV absorber are mixed, and the Na content of the solution is 100 ppb or less by weight.

Inventors

• 료 센이치
• 오우라 유키노부
• 요시다 히로토
• 엔도 도모아키

Assignees

• 가부시기가이샤 디스코

Dates

Publication Date

20260511

Application Date

20260424

Priority Date

20190118

Claims (1)

1. A solution preparation step for preparing a solution in which at least a water-soluble resin, an organic solvent, and a UV absorber are mixed, and A method for manufacturing a protective film for laser dicing, characterized by comprising an ion exchange treatment step in which Na ions in the solution are ion exchanged using a cation exchange resin.

Description

Protective film agent for laser dicing, method of manufacturing protective film agent for laser dicing, and method of processing workpiece using protective film agent for laser dicing The present invention relates to a protective film for laser dicing applied to a workpiece when the workpiece is processed by irradiating it with a laser beam, a method for manufacturing a protective film for laser dicing, and a method for processing a workpiece using a protective film for laser dicing. Electronic devices such as mobile phones and personal computers are equipped with device chips that include electronic circuits. Device chips are manufactured by dividing a workpiece formed from a semiconductor material, such as silicon, into multiple regions along a line of division. For example, a workpiece is divided by ablating it with a laser beam of a wavelength absorbed by the workpiece. However, during ablation, molten material from the workpiece may become debris, scatter, and adhere to the surface of the workpiece, which can degrade the quality of the device chip after division. Therefore, it is known that before performing ablation on a workpiece, a protective film composed of a water-soluble resin and a UV absorber is formed on the surface of the workpiece to prevent debris from adhering directly to the surface of the workpiece (see, for example, Patent Document 1). Incorporating a UV absorber into the protective film offers several advantages. First, when a laser beam with a wavelength in the UV band is irradiated onto the surface of the workpiece on which the protective film is formed, the UV absorber absorbs the laser beam, causing the protective film to undergo ablation processing before the workpiece. Consequently, compared to cases where the workpiece absorbs the laser beam and undergoes ablation processing before the protective film, peeling of the protective film is less likely to occur. Secondly, by utilizing the property of an ultraviolet absorber to emit light (fluorescence) when absorbing ultraviolet light, it is possible to determine whether a protective film is formed on the surface of the workpiece. Additionally, based on the distribution of the light-emitting area, it is possible to evaluate whether the protective film is uniformly formed on the surface of the workpiece. Figure 1 is a schematic diagram of an ion exchange system. FIG. 2(A) is the absorption spectrum of the protective film agent of Example 1, FIG. 2(B) is the absorption spectrum of the protective film agent of Example 2, and FIG. 2(C) is the absorption spectrum of the protective film agent of Comparative Example 1. Figure 3 is the result of the first experiment measuring the time change of absorbance at a wavelength of 420 nm. Figure 4 is the result of the second experiment measuring the time change of absorbance at a wavelength of 420 nm. FIG. 5(A) is a perspective view of a workpiece, and FIG. 5(B) is an enlarged cross-sectional view of a part of the workpiece. Fig. 6 is a perspective view of a frame unit. FIG. 7(A) is a drawing showing a protective film formation step, and FIG. 7(B) is an enlarged cross-sectional view of a part of a workpiece on which a protective film has been formed. Figure 8 is a diagram showing a laser processing step. With reference to the attached drawings, an embodiment related to one aspect of the present invention will be described. First, a protective film agent for laser dicing (hereinafter simply referred to as a protective film agent) will be described. The protective film agent is composed of a solution mixed with at least a water-soluble resin, an organic solvent, and an ultraviolet absorber. The Na (sodium) content in the solution is suppressed to 100 ppb (parts per billion) by weight (i.e., 100 × 10⁻⁷ wt%) or less. By keeping the Na content in the protective film agent to 100 ppb or less, discoloration of the protective film agent can be suppressed. Water-soluble resins are, for example, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polyethylene oxide, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, polyacrylic acid, poly-N-vinylacetamide, or polyglycerin. In addition, one type of material among the materials described above may be used alone, or a combination of two or more types of materials may be used. Organic solvents are organic compounds used to dissolve substances such as ultraviolet absorbers. Organic solvents are, for example, alkylene glycol monoalkyl ethers, alkylene glycol, or alkylene glycol monoalkyl ether acetates. Propylene glycol monomethyl ether can be cited as an example of an alkylene glycol monoalkyl ether. The ultraviolet absorber is, for example, a cinnamic acid derivative. An example of a cinnamic acid derivative is ferulic acid (i.e., 4-hydroxy-3-methoxycinnamic acid), but the cinnamic acid derivative may be isoferulic acid, caffeic acid, sinapinic acid, or chlorogenic acid. The applicant discovered that when a protective film discolors over time