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Preparing Single Crystal Aluminum Films on Amorphous Substrates Disclosure Number: IPCOM000079026D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 34K

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Howard, JK: AUTHOR


The electromigration resistance of narrow line (

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Preparing Single Crystal Aluminum Films on Amorphous Substrates

The electromigration resistance of narrow line ( </- 1 mum) interconnection metallurgy, is an important requirement for large-scale integration in semiconductor devices. Pure Al is attractive because of prior knowledge with etching and contact behavior, but the low-electromigration resistance of Al has posed problems.

In the present method, single-crystal Al films at low temperature ( </- 320 degrees C) are prepared on amorphous substrates. The superior electromigration resistance of single-crystal Al deposited on single-crystal MgO has already been demonstrated. However, the electromigration advantage of the single-crystal films has not been realized in integrated circuit structures, because deposition onto SiO(2) (glass) yields a polycrystalline metal film. The present technique employs a modified zone melting approach to produce a single-crystal pattern from a polycrystalline Al pattern, by use of a single-crystal seed coupled with a moving liquid zone. An interesting feature of this invention is that the submicron line widths are required for a successful result.

As shown in Fig. 1, the electron-beam generated interconnections are characterized by lines which are </-1 mum and have a grain-size stripe width ratio greater than one. After metal film deposition and lift-off, the liquid zone is prepared by adding impurities such as Sn, In, or Cd which form a low temperature ( </- 320 degrees C) eutectic with Al, as shown in Fig. 2.

By powering the Al-Sn composite at accelerated levels of temperature and current, the liquid zone is driven by electromigration toward the anode...