Stacking method and stacking carrier

A stacking carrier and a stacking method are provided. The stacking method is used between a wafer and a stacking carrier having the same shape. The stacking method includes the following steps. Firstly, an adhesive layer is coated on a surface of the carrier. Then, the adhesive layer corresponding to an edge of the carrier is partially removed, thereby defining at least one adhesive layer indentation. Afterwards, the wafer is stacked on the carrier through the adhesive layer having the adhesive layer indentation.

FIELD OF THE INVENTION

The present invention relates to a stacking method and a stacking carrier, and more particularly to a method for stacking a silicon wafer and a carrier and a stacking carrier applied to a wafer.

BACKGROUND OF THE INVENTION

Recently, the trends of fabricating integrated circuit (IC) chips are toward a three-dimensional stacking technology. In other words, the three-dimensional stacking technology is very potential. By means of the three-dimensional stacking technology, chips with different functions and on different substrates may be individually produced by proper fabricating processes and then combined together in a three-dimensional stacking manner. As such, the metallic wire length is shortened and the wire connection resistance is reduced to comply with the miniaturizing and power-saving requirements.

FIGS. 1A,1B and1C are schematic views illustrating a process of stacking an integrated circuit (IC) wafer on a carrier having the same shape according to the prior art. The integrated circuit wafer is attachable on the carrier according to a three-dimensional stacking technology. The common carrier is for example a glass substrate or a semiconductor substrate. As shown inFIG. 1A, an adhesive layer12is formed on a carrier by spin-coating an adhesive. Due to the cohesion of the adhesive, a thicker hump120is formed at the edge of the carrier11. For enhancing the efficacy of bonding the carrier11and the wafer10, the hump120at the edge of the carrier11is removed by solvent. As such, the adhesive layer12on the carrier11has better uniformity (seeFIG. 1B). After the hump120at the edge of the carrier11is removed, a gap13is formed between the carrier11and the wafer10(seeFIG. 1C). In this situation, the wafer10fails to be properly supported, and thus the edge of the wafer10is readily broken. The broken part of the wafer10results in contamination. The problem becomes more serious as the wafer10becomes thinner and thinner.

Therefore, there is a need of providing improved stacking method and carrier in order to obviate the drawbacks encountered from the prior art.

SUMMARY OF THE INVENTION

An object of the present invention provides a stacking method for use between a wafer and a carrier having the same shape in order to avoid the problem of causing contamination from the broken wafer edge.

Another object of the present invention provides a stacking carrier applied to a wafer having the same shape in order to avoid the problem of causing contamination from the broken wafer edge.

In accordance with an aspect of the present invention, there is provided a stacking method. The stacking method includes the following steps. Firstly, an adhesive layer is coated on a surface of the carrier. Then, the adhesive layer corresponding to an edge of the carrier is partially removed, thereby defining at least one adhesive layer indentation. Afterwards, the wafer is stacked on the carrier through the adhesive layer having the adhesive layer indentation.

In accordance with another aspect of the present invention, there is provided a stacking carrier. The stacking carrier includes a carrier body, an adhesive layer and at least one adhesive layer indentation. The adhesive layer overlies the carrier body for providing adhesion required to stack the wafer on the carrier body. The at least one adhesive layer indentation is formed at an edge of the adhesive layer.

In an embodiment, the adhesive layer is formed by spin-coating a photosensing material on a surface of the carrier. In addition, the at least one adhesive layer indentation is defined by performing a photolithography and etching procedure to partially remove the adhesive layer corresponding to the edge of the carrier.

In an embodiment, the at least one adhesive layer indentation includes a plurality of circular indentations, which are separated from each other. Alternatively, the at least one adhesive layer indentation includes a plurality of saw-toothed, which are in communication with each other to collectively form an indentation band.

In an embodiment, the carrier body is a glass substrate or a semiconductor substrate, and the wafer is a semiconductor wafer.

In an embodiment, a thicker hump is formed at an edge of the carrier body.

In accordance with the present invention, the wafer is stacked on the carrier through the use of an adhesive layer having at least one adhesive layer indentation. As a consequence, the attaching efficacy of stacking the wafer on the carrier is enhanced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 2A,2B and2C are schematic views illustrating a process of stacking an integrated circuit wafer on a carrier having the same shape according to an embodiment of the present invention. The integrated circuit wafer20is attachable on the carrier21according to a three-dimensional stacking technology. An example of the carrier21includes but is not limited to a glass substrate or a semiconductor substrate. An example of the wafer20is a semiconductor wafer such as a silicon wafer. As shown inFIG. 2A, an adhesive layer22is formed on a carrier by spin-coating an adhesive. Due to the cohesion of the adhesive, a thicker hump220is formed at the edge of the carrier21. For avoiding generation of the gap between the carrier21and the wafer20after the wafer20is placed on the carrier21, the adhesive layer22at the edge of the carrier21is partially removed, so that at least one adhesive layer adhesive layer indentation221is defined at the edge of the carrier21(seeFIG. 2B). Next, the wafer20is stacked on the carrier21through the adhesive layer22. In response to an external force exerted on the wafer20, the edge hump220is squeezed and filled into the nearby adhesive layer adhesive layer indentation221. The combination of wafer20and the carrier21is shown inFIG. 2C. In accordance with the stacking method of the present invention, the problem of generating the gap in the prior art will be avoided. As a consequence, the possibility of causing contamination from the broken wafer edge will be minimized.

FIGS. 3A and 3Bare schematic views illustrating the configurations of two exemplary adhesive layer indentations defined at the edge of the carrier according to the present invention. As shown inFIG. 3A, the edge of the adhesive layer22has a plurality of circular indentations30, which are separated from each other. The circular indentations30may run through the adhesive layer22to expose the underlying carrier body39. Alternatively, the circular indentations30do not run through the adhesive layer22, and thus the underlying carrier body39is not exposed. The depth of the circular indentation30is not restricted as long as the circular indentation30could provide a space for filling the edge hump220. As shown inFIG. 3B, the edge of the adhesive layer22has a plurality of saw-toothed indentations31, which are in communication with each other to collectively form an adhesive layer indentation band38. Similarly, these saw-toothed indentations31may run through the adhesive layer22to expose the underlying carrier body39. Alternatively, the saw-toothed indentations31do not run through the adhesive layer22, and thus the underlying carrier body39is not exposed. The depth of the saw-toothed indentations31is not restricted as long as the circular indentation30could provide a space for filling the edge hump220.

Moreover, the adhesive layer22is made of a photosensing material (e.g. liquid photoresist material or dry-film photoresist material such as polyimide). The above adhesive layer indentations may be formed by performing a photolithography and etching procedure on the photosensing material. Alternatively, the adhesive layer22may be made of a non-photosensing material, and other patterning procedure may be performed to define the adhesive layer indentations.

From the above description, the stacking method of the present invention is capable of avoiding generation of the gap between the carrier and the wafer. As a consequence, the possibility of causing contamination from the broken wafer edge will be minimized.