Circular Test Pads on Scribe Street Area

Abstract

A semiconductor wafer design and process having test pads (36) reducing cracks generated during the wafer saw process from extending into and damaging adjacent die. The present invention provides a plurality of circular test pads (36) in a wafer scribe street (34) such that any cracks generated in the test pad during wafer saw self terminate in the periphery of the circular test pad. By providing a curved test pad periphery, cracks will tend to propagate along the edges of the test pads and self terminate therein. The circular test pads avoid any sharp corners as is conventional in rectangular test pads which tend to facilitate the extension of cracks from corners to extend into the adjacent wafer die (32). The present invention utilizes existing semiconductor fab processing and utilizes new reticle sets to define the curved test pads.

Description

[0001] This application is a divisional of co-pending application Ser. No. 10 / 145,442 filed May 14, 2002, the contents of which are herein incorporated by reference in its entirety.FIELD OF THE INVENTION [0002] The present invention is generally related to semiconductor wafer processing, and more particularly to scribe streets extending between formed active areas and test pads located thereon for testing the active devices. BACKGROUND OF THE INVENTION [0003] Integrated circuits are typically defined on a semiconductor wafer using a variety of wafer fab processes. Each of the formed active circuit areas, later forming integrated circuits after dicing and packaging, are physically separated from one another on the wafer by an elongated region commonly referred to as a scribe street. These wafers are typically cut along the scribe street after circuit testing using a conventional saw process. [0004] In addition to the active circuitry formed on the semiconductor wafer, test pads are a...

AI Technical Summary

Benefits of technology

The present invention is a new design for wafers and a process for making them. The design includes circular test pads that have a curved profile, preferably a round periphery. This design prevents cracks from forming in the test pads and spreading into the active circuitry of the die, which increases the yield of wafers. The process for making these wafers is simple and does not require any major changes in the manufacturing process. The invention also reduces yield loss and reliability risks associated with cracks in the wafer.

Problems solved by technology

Accordingly, even slight propagation of cracks in the scribe street formed during the wafer saw process eventually results in damaged circuitry since the design of conventional test pads does not prevent them from extending into the active circuitry area 12, as depicted in FIG. 2.

These cracks render the particular die 12 non-functional, thus reducing the overall yield of the die which can be fabricated from the wafers.

However, with the continued reduction in scribe street widths with the introduction of new technologies, and in an effort to maximize wafer yield, these cracks are becoming an increasing problem and a reduction in wafer yield.

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