Effect of synchronized bias in the deposition of TiB2 thin films using high power impulse magnetron sputtering

• Titanium diboride thin films have been deposited from a compound TiB2 target on Si(001) substrates at a temperature of 500 degrees C using high power impulse magnetron sputtering (HiPIMS) at a frequency of 1000 Hz and pulse lengths of 20 and 40 mu s. A -60V bias pulse of different pulse length was applied at different time delay relative to the HiPIMS pulse. The average energy per deposited species, amp;lt; E-D amp;gt; = E-i(J(i)/J(t)), where E-i is the average ion energy and J(i)/J(t) is the ratio of the ion bombarding flux to the total flux of deposited species, is strongly dependent on bias mode. A change in preferred orientation from (101) to (001) is observed when amp;lt; E-D amp;gt; increase above 50 eV. The limited adatom mobility at amp;lt; E-D amp;gt; below 50 eV promote growth of fast growing planes resulting in a (101) texture, while amp;lt; E-D amp;gt; above 50 eV supply sufficient energy for development of the thermodynamically more favorable (001) texture. A linear increase in compressive residual stress with the increase in amp;lt; E-D amp;gt; is also found, due to more intensive Ar+ ion bombardment. Analysis of charge-state-resolved plasma chemistry and ion energy shows that the total flux of bombarding ions contains a higher fraction of B+ when the bias is applied in synchronous with the HiPIMS pulse instead of after, resulting in a lower residual stress at similar values of amp;lt; E-D amp;gt; (cf. -2.0 +/- 0.2 and -2.6 +/- 0.1 GPa). This study shows that use of a bias synchronized in different modes relative to the HiPIMS pulse, can be used as a tool to control amp;lt; E-D amp;gt; and to some extent the type of bombarding species, and hence the microstructure of TiB2 thin films. Published by the AVS.

Subject headings

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Publication and Content Type

ref (subject category)

art (subject category)