Next, in FIG. 8, the semiconductor structure shown in FIG. 7A is flipped over, and the external connectors 155 are attached to a tape 159 (e.g., a dicing tape) supported by a frame 157. Next, the carrier 101 is de-bonded from the dielectric layer 110 by a suitable process, such as etching, grinding, or mechanical peel off. In an embodiment where an adhesive layer (e.g., an LTHC film) is formed between the carrier 101 and the dielectric layer 110, the carrier 101 is de-bonded by exposing the carrier 101 to a laser or UV light. The laser or UV light breaks the chemical bonds of the adhesive layer that binds to the carrier 101, and the carrier 101 can then be easily detached. The adhesive layer, if formed, may be removed by the carrier de-bonding process. Residues of the adhesive layer, if any, may be removed by a cleaning process performed after the carrier de-bonding process.

After de-bonding the carrier 101, openings 116 are formed in the dielectric layer 110 to expose the conductive pillars 119. To form the openings 116, a laser drilling process, an etching process, or the like, may be used. In some embodiments, the etching process is a plasma etch process. Although not shown, solder paste may be formed in the openings 116 using, e.g., a solder paste printing process, in preparation for attaching top packages (see FIG. 9).