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W/W-N Hf/Hf-N and Ti/Ti-N Multilayer Films with Very High Hardness

IP.com Disclosure Number: IPCOM000109573D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 4 page(s) / 162K

Publishing Venue

IBM

Related People

Dove, DB: AUTHOR [+2]

Abstract

There is much interest in improving the hardness of transition metal nitride coating materials. Transition metal nitride films, such as Ti-N, Hf-N etc., are useful hard coating materials. The hardness of transition nitride films reported are between 2,000-3,500 kg/mm2. We have developed a method to make nitride films with hardness approaching 5,000 kg/mm2 or even higher.

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W/W-N Hf/Hf-N and Ti/Ti-N Multilayer Films with Very High Hardness

       There is much interest in improving the hardness of
transition metal nitride coating materials.  Transition metal nitride
films, such as Ti-N, Hf-N etc., are useful hard coating materials.
The hardness of transition nitride films reported are between
2,000-3,500 kg/mm2.  We have developed a method to make nitride films
with hardness approaching 5,000 kg/mm2 or even higher.

      The approach is to make metal/metal-nitride multilayer films in
the form of alternating thin metal layers separated by thin
interlayers of metal sputtered in the presence of nitrogen. Such
multilayer can be made in a simple manner, using a single sputtering
target, by controlling the flow of the reactive gas used to form the
interlayer.  The multi-layer films were deposited by an RF diode
sputtering system.  During the deposition, input power was 400 W, and
the total pressure was 10 mTorr for the preparation of Ti/Ti-N and
Hf/Hf-N multilayer films and 20 mTorr for the W/W-N multilayer films.
The metal thin layers were sputtered in an argon gas environment.
The nitrogen content in the sputtering gas was 20, 25 and 50% for the
deposition of the Ti-N, Hf-N and W-N thin layers, respectively.

      The hardness of W/W-N multilayer films with different
interlayer thickness was measured and plotted as a function of the
inverse square root of the thickness of individual layer as shown in
Fig. 1.  The hardness of homogenous W and W-N films deposited at the
same gas pressure is marked on the same figure.  As the thickness of
each individual layer decreased, the hardness of multilayer films
increased line- arly with the inverse square root of the individual
layer thickness d, as shown in Fig. 1.  Then the hardness did not
increase with the further decreasing of layer thickness.  The
hardness of multilayer films reached a value higher than 3,500 kg/mm2
which is much higher than that of the W and W-N single layer films.

      Hf/Hf-N multilayer films were also studied.  Hardness vs. the
inverse of the square root of the individual layer thickness d for
Hf/Hf-N multilayer films is plotted in Fig. 2.  The hardness of Hf
single metal films...