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Method for hillock-mediated wafer bonding

IP.com Disclosure Number: IPCOM000007313D
Publication Date: 2002-Mar-13
Document File: 2 page(s) / 22K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for hillock-mediated wafer bonding. Benefits include improved ease of manufacturing.

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Method for hillock-mediated wafer bonding

Disclosed is a method for hillock-mediated wafer bonding. Benefits include improved ease of manufacturing.

Background

      The disclosed method addresses the problem of incomplete bonding between wafers caused by height variations of the bonding surfaces. Conventionally, this problem is solved by applying tremendous force to warp the wafers or compress the high spots so that low areas touch and, subsequently, form a bond.

Description

              The disclosed method creates metal-to-metal contact that promotes metal diffusion bonding between two wafers by bridging air gaps between the metal bonding surfaces using vertical hillocks. Height variations across the wafer leave areas with gaps between the metal bonding surfaces. Hillock formation on each bonding face may span the gap. When the hillocks from each side touch, a diffusion bond forms, improving the overall bonding of the wafers.

      Successfully bonded wafers have all the bonding surfaces in mechanical and electrical contact. However, after processing and prior to bonding, wafer surfaces are typically not entirely planar and some bonding surfaces do not touch. Before hillock formation, some bond pads do not make contact (see Figure 1).  For those surfaces that are not in contact initially, the heating phase of the bonding process induces hillock formation. These hillocks extend into the space between the bonding surfaces and bridge the gap. After hillock growth, hanging connections are completed by...