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Highly Localized Non-Bonding Regions in Copper-to-Copper Bonded Stacked Wafers

IP.com Disclosure Number: IPCOM000032203D
Publication Date: 2004-Oct-26
Document File: 4 page(s) / 40K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that creates localized insulating and conducting paths across bonded wafers or dies. Benefits include a solution that enables a signal and power routing layer in both the x and y directions.

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Highly Localized Non-Bonding Regions in Copper-to-Copper Bonded Stacked Wafers

Disclosed is a method that creates localized insulating and conducting paths across bonded wafers or dies. Benefits include a solution that enables a signal and power routing layer in both the x and y directions.

Background

Currently, there is a need to enable controlled copper non-bonding at various lengths for different three-dimensional interconnect applications. These non-bonding areas are desired so that power and signal routing can be achieved between dies and within a die. Presently, there are no solutions implemented to create localized variations in wafer bonding.

General Description

The following are the steps for three implementations of the disclosed method:

First implementation:

1.      After the oxide recess step, treat the sample selectively (or over the entire wafer) with material copper passivation or insulating layers, such as BTA, GX3, SiLK, or another ILD prior to wafer alignment. The material should be electrically insulating, compliant, and have a low copper diffusion constant.

2.      Selectively pattern areas where non-bonding/non-connection is desired, using lithography or other technique. After patterning, use chemicals such as ALEG (containing TMAH, which will remove the organic materials in BTA), to leave a pristine copper surface suitable for bonding.

3.      Selective chemical treatments can also be used to create masks, etching, or photo-definable materials. Such localized treatment of the copper surface can create highly localized non-bonding and bonding regions.

4.      Patterns of copper lines containing local non-bonded regions enable signal routing. The non-bonded regions are created selectively using a chemical process. Figure 1 shows an example of a power grid and signal line using the de-bonded, insulating regions. The thickness of the organic, polymer, or other insulating layer must be less than the approximate compliance of the copper layers for bonding. This is typically in the 100 to 200nm range. Capacitive...