Semiconductor device manufacturing: process – Semiconductor substrate dicing – Having specified scribe region structure
Reexamination Certificate
2000-10-30
2003-06-24
Chaudhuri, Olik (Department: 2823)
Semiconductor device manufacturing: process
Semiconductor substrate dicing
Having specified scribe region structure
C438S113000, C438S114000
Reexamination Certificate
active
06583032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing semiconductor chips, particularly with extremely thin chips which are as thin as 200 &mgr;m or less.
2. Description of Related Art
In the manufacturing process of semiconductor chips, many semiconductor chips are formed on the obverse of a wafer such as a silicon wafer by processing the wafer by a predetermined manner, and the wafer is then diced with a dicing machine along streets, which are formed between the chips, to separate the chips. Because of the increased number of smart cards, cellular phones and laptop personal computers, the semiconductor chips that are assembled into small devices have been required to be light-weighted and small-sized. In view of such requirements, after forming the chips on the obverse of the wafer, the reverse of the wafer is ground by a planarization apparatus so as to make the wafer thin (as thin as 200 &mgr;m or less), and then the wafer is diced to separate chips by the dicing machine. In this dicing, the dicing machine performs a full-cut (a processing method for completely cutting and dividing the wafer) for the wafer along the streets so as to separate the chips.
However, a broken layer (also called a spoiled layer or a damaged layer) is formed on the reverse of the wafer during the reverse face grinding, and the broken layer causes breakage of the extremely thin wafer with the thickness of 200 &mgr;m or less in the process afterwards. Moreover, when completely cutting the extremely thin wafer by the full-cut with the dicing machine, many inferior chips are generated due to chipping (cracks) around the chips, especially chipping (cracks) on the reverse of the wafer.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of the method of manufacturing the semiconductor chips by which extremely thin semiconductor chips can be manufactured without generating cracks or chipping.
In order to achieve the above-described objects, the present invention is directed to a method for manufacturing semiconductor chips, comprising the steps of: grinding a reverse of a wafer so as to shape the wafer in a predetermined thickness, the chips being formed on an obverse of the wafer; removing, by at least one of polishing and etching, a broken layer formed on the reverse of the wafer in the reverse grinding step; forming grooves on the reverse of the wafer in a predetermined depth along streets formed between the chips; and cleaving the wafer along the grooves so as to separate the chips.
According to the present invention, first, the reverse of a wafer, on the obverse of which many chips are formed, is ground so as to shape the wafer with a predetermined thickness. Then, the reverse of the wafer is polished or etched so that the broken layer which is formed during the back grinding is removed. Next, grooves are formed on the reverse of the wafer in a predetermined depth along streets formed between the chips. Finally, the wafer is cleaved along the grooves so as to be divided into separate chips. By polishing or etching the reverse of the wafer after the back grinding so as to remove the broken layer formed during the back grinding, the strength of the chips is improved. Moreover, by dividing the wafer from which the broken layer is removed into separate chips by using the cleavage, cracks and chipping of the reverse of the wafer are effectively reduced.
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Ishikawa Toshihiko
Katagiri Yasushi
Nixon & Peabody LLP
Safran David S.
Tokyo Seimitsu Co. Ltd.
Toledo Fernando
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