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Pre-Bond Wafer Edge Removal to Enable Damage-Free Bonded Wafer Thinning for Three Dimensional Wafer Stacking Technology

IP.com Disclosure Number: IPCOM000124179D
Publication Date: 2005-Apr-11
Document File: 2 page(s) / 147K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for preventing edge chipping and bottom wafer surface damage during the thinning of one side of a bonded wafer pair. The disclosed method removes the outer edge of the wafer so it can be thinned prior to bonding. Benefits include a solution that cleanly defines the edge of the thinned wafer with greater accuracy and less damage than the current process.

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Pre-Bond Wafer Edge Removal to Enable Damage-Free Bonded Wafer Thinning for Three Dimensional Wafer Stacking Technology

Disclosed is a method for preventing edge chipping and bottom wafer surface damage during the thinning of one side of a bonded wafer pair. The disclosed method removes the outer edge of the wafer so it can be thinned prior to bonding. Benefits include a solution that cleanly defines the edge of the thinned wafer with greater accuracy and less damage than the current process.

Background

Edge chipping and wafer surface damage during bonded wafer thinning occurs because the beveled edges of the bonded wafers are not in physical contact with each other; the unsupported edge of the thinned wafer becomes too thin and breaks.  The current state of the art removes the edge of the wafer after post-bond by edge grinding or by using a dicing saw. Removal of this edge can result in damage to the surface of the underlying wafer. This damage can propagate and cause wafer breakage during shipping and/or thermal cycling (see Figures 1a and 1b).

General Description

The disclosed method removes the wafer edge before the bonding process. The wafer edge is shaped so that the profile is vertical or sloped (see Figure 2), so there is no undercut during the thinning process.  The bottom wafer remains free of damage during this process. Any means can be used to remove the wafer edge, including grinding, sawing, laser dicing, and polishing.

In the disclosed method, wafers which h...