Packaging method of molded wafer level chip scale package (WLCSP)

摘要

A WLCSP method comprises: depositing a metal bump on bonding pads of chips; forming a first packaging layer at front surface of wafer to cover metal bumps while forming an un-covered ring at the edge of wafer to expose the ends of each scribe line located between two adjacent chips; thinning first packaging layer to expose metal bumps; forming a groove on front surface of first packaging layer along each scribe line by cutting along a straight line extended by two ends of scribe line exposed on front surface of un-covered ring; grinding back surface of wafer to form a recessed space and a support ring at the edge of the wafer; depositing a metal layer at bottom surface of wafer in recessed space; cutting off the edge portion of wafer; and separating individual chips from wafer by cutting through first packaging layer, the wafer and metal layer along groove.

主权项

1. A WLCSP method for packaging semiconductor chips formed at a front surface of a semiconductor wafer, each semiconductor chip comprising a plurality of metal bonding pads formed at its front surface, comprising the steps of:
depositing a metal bump on each of the metal bonding pads; forming a first packaging layer at the front surface of the wafer to cover the metal bump, wherein the radius of the first packaging layer is smaller than the radius of the wafer forming an un-covered ring at the edge of the wafer, wherein two ends of each scribe line located between two adjacent semiconductor chips extend on a front surface of the un-covered ring; thinning the first packaging layer to expose the metal bump from the first packaging layer; forming a cutting groove on the front surface of the thinned first packaging layer along each scribe line by cutting on the first packaging layer along a straight line extended by the two ends of the scribe line exposed on the front surface of the un-covered ring such that a depth of the cutting groove is shallower than a thickness of the thinned first packaging layer; grinding at the back surface of the wafer to form a recessed space at the back surface of the wafer and a support ring at the edge of the wafer; depositing a metal layer at the bottom surface of the wafer in the recessed space; cutting off the edge portion of the wafer; and separating individual semiconductor chips from the wafer by cutting through the first packaging layer, the wafer and the metal layer along the cutting groove, wherein the first packaging layer is cut into a plurality of top packaging layers each of which covers the front surface of each semiconductor chip with the metal bump exposed from the top packaging layer, and wherein the metal layer is cut into a plurality of bottom metal layers each of which covers the back surface of each semiconductor chip.