Browse Prior Art Database

The Decoration of Copper Grains

IP.com Disclosure Number: IPCOM000084994D
Publication Date: 2005-Mar-02
Document File: 2 page(s) / 97K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to decorate polycrystalline copper surfaces by using a wet chemical clean process. The disclosed method targets grain boundaries between various copper grains without causing bulk etch. Benefits include a solution that can conduct grain analysis with both in-fabrication and out-of-fabrication techniques.

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The Decoration of Copper Grains

Disclosed is a method to decorate polycrystalline copper surfaces by using a wet chemical clean process. The disclosed method targets grain boundaries between various copper grains without causing bulk etch. Benefits include a solution that can conduct grain analysis with both in-fabrication and out-of-fabrication techniques.

Background

Currently, the analysis of the copper grain structures in the interconnect is done by using destructive, out-of-fabrication analytical equipment; this process produces only localized results and is time consuming. Figure 1 shows no treatment to the copper surface, post CMP.

General Description

The key element of the disclosed method is a wet chemical clean process containing dissolved ammonia.  The chemistry is of a basic pH greater than eight, and contains ammonium ions and dissolved ammonia gas in equilibrium. The amount of ammonia in solution is determined by the solution pH and the solubility of the NH3 in the liquid matrix. Ammonium ions are supplied by using NH4OH, using salt (e.g. NH4Cl), or by bubbling ammonia gas through the solution. Furthermore, the chemistry can contain organic surfactants, buffers, and trace transition metal ions to further modulate the selectivity and bulk etch characteristics. Figure 2 shows the copper surface post treatment with the disclosed method. The following are the process steps for the disclosed method:

§         Formation of copper interconnects by using barrier/seed depositi...