Substrate bonding with local bonding region shape control

Abstract

A method of bonding a smaller substrate, such as a die, to a larger substrate, such as a wafer. The method includes forming a bulge at a front side of the larger substrate by releasably securing a backside of the larger substrate to a rigid chuck, bonding the smaller substrate to the bulge at the front side of the larger substrate, and allowing the bulge to flatten by releasing the larger substrate from the rigid chuck. A variable thickness material on the backside of the larger substrate induces the bulge at the front side of the larger substrate. The method may also include forming the variable thickness material on the backside of the larger substrate. Multiple bulges may be induced at the front side of the larger substrate. Multiple smaller substrates may be bonded to a single bulge.

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