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Method for forming Tungsten Vias for Copper Interconnects

IP.com Disclosure Number: IPCOM000192357D
Original Publication Date: 2010-Jan-21
Included in the Prior Art Database: 2010-Jan-21
Document File: 2 page(s) / 193K

Publishing Venue

IBM

Abstract

A method for forming tungsten vias for Copper (Cu) interconnects using Chemical Vapor Deposition (CVD) is disclosed.

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Method for forming Tungsten Vias for Copper Interconnects

Disclosed is a method for forming tungsten vias for Copper (Cu) interconnects using Chemical Vapor Deposition (CVD).

Tungsten (W) vias may be used with Cu interconnect technology to connect a metal Aluminum (Al) layer to underlying Cu interconnects. The deposition of W using CVD involves deposition of an initial, thin layer of W formed by Silane (SiH4) reduction of Tungsten Hexaflouride (WF6), followed by bulk deposition of W using Hydrogen (H2) reduction of WF6. However, the SiH4 reduction process for W deposition can be detrimental to Cu interconnects. Cu reacts rapidly with SiH4 at the W deposition

temperature of around 400

°C, resulting in Cu silicide formation. The Cu silicide

formation leads to depletion of Cu in the interconnect, resulting in the formation of voids as shown in Fig.1.

Figure 1

The present method eliminates the SiH4 reduction step from the deposition process. A tungsten seed layer is formed using Physical Vapor Deposition (PVD). The tungsten seed layer is required because nucleation of CVD W is inhibited on Titanium nitride (TiN) barriers when using the H2 reduction process.

Fig. 2 illustrates the method of forming tungsten vias for Cu interconnects. The method

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disclosed herein involves creation...