Method of processing wafer

Abstract

A method of processing a wafer is provided. The method includes a cutting groove forming step of forming a cutting groove having a depth corresponding to a thickness of a device chip from a front sideof the wafer along a predetermined dividing line; a sealing step of sealing the front surface of the wafer with a sealing material; a grinding step of grinding the wafer from the back side of the wafer to the finished thickness to expose the sealing material in the cutting groove; an alignment step of detecting an alignment mark by an infrared ray imaging member photographing the front side of the wafer from the front side of the wafer through the sealing material, and detecting a predetermined dividing line for laser processing according to the alignment mark; a modified layer forming step of positioning the condensing point of the laser beam having a wavelength of transparency to the sealing material inside the sealing material in the cutting groove to radiate the laser beam to form a modified layer; and a dividing step of applying an external force to the sealing material in the cutting groove and dividing the wafer into respective device chips with a front surface and four side surfaces surrounded by the sealing material with the modified layer as a dividing starting point.

Description

technical field [0001] The invention relates to a wafer processing method, and the wafer is processed to form a 5S mold package. Background technique [0002] As a structure to achieve miniaturization and high-density mounting of various devices such as LSI and NAND flash memory, for example, a chip size package (CSP) in which device chips are packaged in chip sizes has been put into practical use, And it is widely used in mobile phones, smart phones, etc. In addition, among these CSPs, in recent years, a CSP that seals not only the front surface of a chip but also the entire side surface of a chip with a sealing material, that is, a so-called 5S molded package, has been developed and put into practical use. [0003] Conventional 5S molded packages are produced through the following steps. [0004] (1) External connection terminals called devices (circuits) and bumps are formed on the front surface of a semiconductor wafer (hereinafter, sometimes roughly referred to as a w...

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Problems solved by technology

[0013] However, in the alignment method described in the above publication, instead of the cutting tool for dicing, it is necessary to attach a wide cutting tool for edge trimming to the spindle to remove the sealing material on the outer peripheral portion of the wafer. It takes time and labor to replace the cutting tool and remove the sealing material on the outer peripheral part by edge trimming, and there is a problem of poor productivity

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