US-12628599-B2 - Manufacturing method of chips

US12628599B2US 12628599 B2US12628599 B2US 12628599B2US-12628599-B2

Abstract

First penetrating paths that penetrate an insulating film are formed by irradiation with a laser beam along the boundaries of multiple devices from a surface side of the insulating film prior to formation of a mask used when a wafer is divided by plasma etching (protective film forming step and second laser beam irradiation step). In this case, the irradiation condition of the laser beam for removing the desired part of the insulating film and the irradiation condition of the laser beam for forming the mask, that is, for removing the desired part of a protective film, can each be set to a preferable condition. As a result, it becomes possible to improve the processing accuracy when the wafer is divided to manufacture chips.

Inventors

Kentaro Odanaka

Assignees

DISCO CORPORATION

Dates

Publication Date: 20260512
Application Date: 20230413
Priority Date: 20220510

Claims (4)

1 . A manufacturing method of chips in which a wafer having a substrate and multiple devices disposed on a front surface side of the substrate with interposition of an insulating film is divided along boundaries of the multiple devices to manufacture the chips, the manufacturing method comprising: a first laser beam irradiation step of forming first penetrating paths that penetrate the insulating film and expose the substrate, by executing irradiation with a laser beam along the boundaries from a front surface side of the insulating film under a first irradiation condition; a protective film forming step of forming a single layer of a protective film to cover the multiple devices, the insulating film, and the substrate exposed at the first penetrating paths, after the first laser beam irradiation step; a second laser beam irradiation step of forming second penetrating paths that penetrate the protective film formed at the first penetrating paths and expose the substrate while the protective film remains on and directly in contact with side surfaces of the multiple devices and the insulating film, and exposed side surfaces of the substrate formed by the first penetrating paths, by executing irradiation with the laser beam along the boundaries from a surface side of the protective film under a second irradiation condition different from the first irradiation condition, after the protective film forming step; a dividing step of executing plasma etching from the surface side of the protective film until the substrate is divided along the boundaries, after the second laser beam irradiation step; and separating the wafer into the chips, after the dividing step, wherein each of the chips includes one of the devices, the insulating film, the substrate and the single layer of the protective film that covers the one of the devices, the insulating film and the substrate.
2 . The manufacturing method of chips according to claim 1 , wherein the insulating film is composed of a material through which the laser beam transmits.
3 . The manufacturing method of chips according to claim 1 , wherein the protective film forming step includes applying a liquid resin to a front surface of the wafer to form the single layer of the protective film.
4 . The manufacturing method of chips according to claim 1 , wherein the protective film is a water-soluble protective film.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a manufacturing method of chips in which a wafer having a substrate and multiple devices disposed on the front surface side of the substrate with the interposition of an insulating film is divided along the boundaries of the multiple devices to manufacture the chips. Description of the Related Art Chips of a device such as an integrated circuit (IC) are constituent elements indispensable in various kinds of electronic equipment such as mobile phones and personal computers. Such chips are manufactured by dividing a wafer in which multiple devices are formed, along the boundaries of the multiple devices, for example. As a method for dividing the wafer as above, there has been proposed a technique in which a mask is provided on the front surface of the wafer in such a manner that the boundaries are exposed and thereafter plasma etching is executed for this wafer (for example, refer to Japanese Patent Laid-open No. 2016-207737). For example, this mask is formed by covering the front surface of the wafer by a protective film containing a light absorbing agent and then executing irradiation with a laser beam along the boundaries from the surface side of the protective film to remove part of the protective film. SUMMARY OF THE INVENTION For the purpose of enhancement in the quality of chips, the chips are manufactured from a wafer having a substrate composed of a semiconductor and multiple devices disposed on the front surface side of the substrate with the interposition of a film composed of an insulator (insulating film), what is generally called a silicon-on-insulator (SOI) wafer, in some cases. Further, this SOI wafer is sometimes divided by plasma etching as described above. In this case, part of the insulating film is frequently removed together with part of the protective film provided on the front surface of the wafer by the laser beam with which irradiation is executed for forming the mask for plasma etching. Typically, this part of the insulating film is not directly removed by the irradiation with the laser beam. Specifically, because the insulator has high band-gap energy, this laser beam is typically transmitted through the insulating film. On the other hand, the laser beam that has transmitted through the insulating film is absorbed by the semiconductor that configures the substrate. In this case, laser ablation occurs in the vicinity of the front surface of the substrate. Moreover, part of the insulating film located at the boundaries of the multiple devices evaporates to be removed in association with this laser ablation. However, when the insulating film is thick and/or when the laser ablation occurs in a broad range in the front surface of the substrate, there is a possibility that it becomes difficult to remove the desired part of the insulating film or a broad part of the insulating film is removed, that is, film separation occurs. In view of this point, an object of the present invention is to provide a manufacturing method of chips that can improve the processing accuracy when a wafer having a substrate and multiple devices disposed on the front surface side of the substrate with the interposition of an insulating film is divided by plasma etching to manufacture the chips. In accordance with an aspect of the present invention, there is provided a manufacturing method of chips in which a wafer having a substrate and multiple devices disposed on a front surface side of the substrate with the interposition of an insulating film is divided along boundaries of the multiple devices to manufacture the chips. The manufacturing method includes a first laser beam irradiation step of forming first penetrating paths that penetrate the insulating film and expose the substrate, by executing irradiation with a laser beam along the boundaries from a surface side of the insulating film under a first irradiation condition, and a protective film forming step of forming a protective film to cover the multiple devices, the insulating film, and the substrate exposed at the first penetrating paths, after the first laser beam irradiation step. The manufacturing method includes also a second laser beam irradiation step of forming second penetrating paths that penetrate the protective film formed at the first penetrating paths and expose the substrate, by executing irradiation with the laser beam along the boundaries from a surface side of the protective film under a second irradiation condition different from the first irradiation condition, after the protective film forming step, and a dividing step of executing plasma etching from the surface side of the protective film until the substrate is divided along the boundaries, after the second laser beam irradiation step. Preferably, the insulating film is composed of a material through which the laser beam transmits. In the present invention, the first penetrating paths that penetrate t