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Passivating Exposed Copper Surfaces Between Bonded Wafers or Dice Using ALD

IP.com Disclosure Number: IPCOM000030142D
Publication Date: 2004-Jul-29
Document File: 2 page(s) / 42K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses ALD (atomic layer deposition) to deposit film between bonded wafers or dice to stop the copper from corroding and diffusing. Benefits include a solution that speeds vapor diffusion and eliminates potential shorting and leakage problems associated with metal passivation layers.

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Passivating Exposed Copper Surfaces Between Bonded Wafers or Dice Using ALD

Disclosed is a method that uses ALD (atomic layer deposition) to deposit film between bonded wafers or dice to stop the copper from corroding and diffusing. Benefits include a solution that speeds vapor diffusion and eliminates potential shorting and leakage problems associated with metal passivation layers.

Background

Currently a problem exists where corroded exposed copper migrates under the biased thermal stressing after stacking wafers or dice with copper-copper bonds. Presently there are no known solutions for this problem, but there are several solutions underway to solve the problem by selectively depositing passivating metal layers over the copper, or using polymer underfill materials.

General Description

The following are the steps needed to create the disclosed method:

1.      Stack the wafers using copper-copper bonds (individual die can not have a guard ring at the bonding layers).

2.      Cleave the wafers into the die (optional).

3.      Place stacked  the wafers or die into a vacuum chamber.

4.      Pump the first gas into the chamber (e.g. triethylaluminum for Al2O3).

5.      Evacuate the vacuum chamber.

6.      Pump the second gas into the chamber (e.g. water for Al2O3).

7.      Evacuate the vacuum chamber.

8.      Repeat steps 4 through 7 until the desired thickness of insulating layer is deposited.  Approximately 50 - 100 angstroms of material should be sufficient to inhibit copper corrosion and diffusion during BTS (biased  thermal stressing).

Any insulating material that can b...