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Method for ultra-thin composite barrier layers for Cu interconnects

IP.com Disclosure Number: IPCOM000030148D
Publication Date: 2004-Jul-29
Document File: 4 page(s) / 25K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for ultra-thin composite barrier layers for Cu interconnects. Benefits include improved functionality, improved performance, and improved reliability.

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Method for ultra-thin composite barrier layers for Cu interconnects

Disclosed is a method for ultra-thin composite barrier layers for Cu interconnects. Benefits include improved functionality, improved performance, and improved reliability.

Background

      Conventional semiconductor processing for forming copper interconnects can have some results that require improvement, including (see Figure 1):

•             Poor adhesion occurs between atomic layer deposition (ALD) TaN and physical vapor deposition (PVD) Cu as indicated by Cu agglomeration during thermal annealing

•             Poor adhesion between ALD or chemical vapor deposition (CVD) TiN and SiCOH or SiOF low dielectric constant (K) materials.

      The problem of poor adhesion between ALD TaN and PVD Cu is conventionally solved by using a PVD capping layer of a refractory metal. However, conventional or improved PVD deposition technique may not be capable to provide a uniform and thin layer of material needed for extreme narrow trenches and vias. To address the above-mentioned issues with adhesion to the dielectric substrate and the Cu, more than one ultra-thin ALD layer is used. For example, with a composite layer of ALD TaN followed by ALD TiN, Cu agglomeration is eliminated when Cu is in contact with ALD TiN. The ALD TaN layer contacts the underlying low-K interlayer dielectric (ILD) material to maintain the known good adhesion. One or more ALD layers can be inserted between ALD TaN and ALD TiN, if needed, to provide robust barrier properties against Cu atom diffusion into the ILD layers.

General description

      The disclosed method is the deposition of more than one thin barrier films by PVD, CVD, or ALD. This composite stack is an effective barrier to Cu diffusion and improves the adhesion (wetting) to the Cu seed layer and the ILD layer. For example, an ultra thin composite stack can consist of an ALD TaN layer as the underlying barrier layer and another ultra thin film of TiN, W, WN, AlN, Pt, Al, Ni, Au, and Ag can be deposited by ALD, CVD or PVD techniques. The composite film is deposited sequentially in the same reaction chamber of different reaction chambers in a cluster tool.

              The key elements of the disclosed method include:

•             More than one ultra-thin barrier layer, particularly ALD TaN and ALD TiN in the formation of Cu interconnects

•             Line resistance reduction by the use of ultra-thin barrier layers, maximizing the total cross sectional area of Cu inside a feature

•             Improved barrier/seed fi...