Synthesis of hard TiN coatings with suppressed columnar growth and reducedstress

Titanium nitride normally grows with a columnar grain structure. In this st udy, we prepared TiN/CNx multilayered coatings with the intent of using the CNx layers to interrupt the grain growth of TiN to attain an equiaxed grai n structure. The TiN/CNx coatings were synthesized by direct current magnet ron sputtering. Our investigations showed that three important process cond itions are required to obtain superhard and smooth TiN/CNx coatings with lo w internal stress: (i) a TiN buffer layer with strong (111) texture; (ii) p roper bias during the growth of the TiN buffer and TiN/CNx coating; and (ii i) small thickness for the CN, layers. (C) 1999 American Vacuum Society. [S 0734-2101(99)02505-1].