The effect of addition of Al in ZrO2 thin film on its resistance to cracking

The paper reports on the structure, mechanical and optical properties of sputtered Zr-Al-O films. The Zr-Al-O films with Zr/Al > 1 and Zr/Al < 1 were prepared by a reactive sputtering using ac pulse dUal magnetrons. The magnetrons were equipped with a target composed of AI plate (circle divide = 50 mm) fixed to the magnetron cathode by a Zr fixing ring with inner diameter circle divide(in). The content of Al in the Zr-Al-O film was controlled by circle divide(in). It makes possible to control effectively the structure of the Zr-Al-O film determined by a mixture of the crystalline ZrO2 phase and the amorphous Al2O3 phase. The effect of Al content on the structure, mechanical and optical properties of the Zr-Al-O film is investigated in detail. It was found that (i) the Zr-Al-O films with Zr/Al < 1 are X-ray amorphous and exhibit low hardness (H <= 13 GPa), an effective Young's modulus E* resulting in a low H/E* < 0.1 ratio and low elastic recovery W-e <= 60 and (ii) the Zr-Al-O films with Zr/Al > 1 are crystalline and exhibit high hardness (H = 18 to 19 GPa), an E* satisfying a high H/E* >= 0.1 ratio, high W-e up to 78% and strongly enhanced resistance to cracking during bending even for thick films up to 5 mu m. (c) 2012 Elsevier B.V. All rights reserved.