Thin wafer handling structure and method

The present application claims priority of U.S. Provisional Patent Application Ser. No. 61/221,890 filed on Jun. 30, 2009 which is incorporated herein by reference in its entirety.

This disclosure relates generally to wafer processing and more particularly to a thin wafer handling structure and method to facilitate bonding and debonding.

In semiconductor wafer processing, temporary bonding and debonding techniques are necessary for thin wafer backside processes. The wafer is bonded on rigid carrier by adhesive layers. After grinding and/or other post-bonding processes the wafer is debonded from the rigid carrier.

One of the conventional debonding methods uses a laser on a light-to-heat conversion layer (LTHC) to release the carrier, and then peel off the adhesive. The adhesive material is UV-cured material, e.g. thermal setting polymer that cannot be stripped by chemicals and should be peeled off instead. This method suffers chemical residue after debonding. Also, the laser release layer has a weak chemical resistance during backside processes.

Another conventional method uses chemical release. This method chemically dissolves the adhesive to release the wafer from the carrier. This method needs perforated glass and easily induces cross contamination. The process speed, e.g. wafers per hour (WPH) is also slow compared to the other methods.

Yet another conventional method is thermal sliding. This method treats the wafer and carrier with heat and then slides them apart. This method needs higher debonding temperatures and may adversely impact the interconnection scheme.

Accordingly, new structure and methods are desired for a robust wafer bonding to ensure surface cleanness after debonding and to have good chemical resistance during post-bonding processes.

For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an example of a thin wafer handling structure to facilitate bonding and debonding according to one aspect of the present disclosure; and

FIG. 2 illustrates an example method to facilitate thin wafer bonding and debonding according to another aspect of the present disclosure.

The making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the disclosure, and do not limit the scope of the invention.

A thin wafer handling structure and method to facilitate bonding and debonding for wafer process are provided. Throughout the various views and illustrative embodiments of the present disclosure, like reference numbers are used to designate like elements.

FIG. 1 illustrates an example of a thin wafer handling structure to facilitate bonding and debonding according to one aspect of the present disclosure. The wafer 102 is bonded on the carrier 108 using two layers in between, i.e. the release layer 106 and the adhesive layer 104 . The release layer 106 is applied on carrier 108 by coating or lamination processes followed by removal of the outer most 0.1 mm-3 mm of the release layer 106 from the edge of the carrier by edge bead removal (EBR).

EBR removes a build-up of material at the wafer edges. Without any intervention, excess material may accumulate at the edge of the wafer at up to several times the nominal thickness of the layer. Such a condition would present a significant contamination risk for process equipment. For chemical EBR, solvent is dispensed on the edge of the wafer as the wafer is rotated immediately after coating.

The adhesive layer 104 is applied on wafer 102 by coating or lamination process, and should be capable of being removed by solvent, e.g. thermal plastic polymer can be used as the adhesive layer 104 in one preferred embodiment. The carrier 108 and the wafer 102 are bonded together by UV light or thermal energy.

FIG. 2 illustrates an example method to facilitate thin wafer bonding and debonding according to another aspect of the present disclosure. At step 202 , the release layer 106 is applied on the carrier 108 by coating or lamination. Spin coating can be used for adhesive layer application according to one embodiment. At step 204 , the adhesive layer 104 is applied on the wafer 102 by coating or lamination. At step 206 , the carrier 108 and the wafer 102 are bonded together with the release layer 106 and the adhesive layer 104 in between and cured by thermal energy or UV light. The adhesive can be pre-baked prior to bonding. At step 208 , the wafer goes through post-bonding processes, e.g. grinding, wafer backside processing, etc. The wafer backside processing may include ion implantation, annealing, etching, sputtering, evaporation, and/or metallization, etc.

After the post-bonding processes, the wafer goes through the debonding processes, which includes carrier release and post cleaning. At step 210 , the carrier 108 is released by energy application on the release layer 106 , e.g. UV light or light from a laser. The thin wafer 102 can be attached on dicing frame for dicing tape lamination prior to releasing the carrier. Then the wafer 102 surface is cleaned by chemical soaking in solvent to remove any residue of the adhesive layer 104 . For example, an adhesive layer 104 using thermal plastic polymer can be chemically cleaned with a solvent. A skilled person in the art will appreciate that there can be many embodiment variations of this disclosure.

The advantageous features of the present disclosure include surface cleanness after debonding and good chemical resistance during post-bonding processes.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure.