Substrate bias effects during diamond like carbon film deposition by microwave ECR plasma CVD R.M. Dey d , S.B. Singh a , A. Biswas b , R.B. Tokas b , N. Chand a , S. Venkateshwaran c , D. Bhattacharya b , N.K. Sahoo b , S.W. Gosavi d , S.K. Kulkarni d , D.S. Patil a, * a Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India b Spectroscopy Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India c High Pressure Physics Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India d DST Unit on Nanoscience, Department of Physics, University of Pune, Ganeshkhind, Pune 411 007, India Received 24 November 2006; accepted 29 March 2007 Available online 18 April 2007 Abstract Diamond like carbon (DLC) coatings were deposited on silicon(1 1 1) substrates by microwave electron cyclotron resonance (ECR) plasma CVD process using a plasma of Ar and CH 4 gases under the influence of DC self bias generated on the substrates by application of RF (13.56 MHz) power. DLC coatings were deposited under the varying influence of DC bias (60 V to 150 V) on the Si substrates. Deposited films were analyzed by different techniques like: X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), atomic force microscopy (AFM), Hardness and elastic modulus determination technique, Raman spectroscopy, scanning electron microscopy (SEM) and contact angle measurement. The results indicate that the film grown at 100 V bias has optimised properties like high sp 3 /sp 2 ratio of carbon bonding, high refractive index (2.26–2.17) over wide spectral range 400–1200 nm, low roughness of 0.8 nm, high contact angle (80°) compared to the films deposited at other bias voltages (60 V and 150 V). The results are consistent with each other and find august explanation under the subplantation model for DLC growth. Ó 2007 Elsevier B.V. All rights reserved. PACS: 81.15.Gh; 81.05.Uw; 87.64.Je; 52.50.Sw Keywords: Diamond like carbon; Electron cyclotron resonance; Atomic force microscopy; X-ray photoelectron spectroscopy; Spectroscopic ellipsometry; Contact angle; Roughness 1. Introduction Diamond like carbon exhibits combination of properties similar to diamond such as high hardness, transparency over wide wavelength region particularly infrared, low coefficient of friction with metal surfaces and high chemical inertness [1]. The most attractive feature of DLC is that they can be grown at relatively low temperature on varie- ties of substrates and the extent of the properties can be tuned in contrast to the diamond deposition techniques requiring high temperature. This makes DLC an important technological material. DLC can be grown by a number of different techniques like ion beam deposition [2,3], magne- tron sputtering [4,5] and microwave assisted CVD [6,7]. The resplendent common feature relevant to these tech- niques is that the property of the deposited DLC film is governed by the energy of the impinging hydrocarbon ion species on the substrates. The negative bias voltage applied to the substrate during growth dictates the ion energy and hence the film properties. The objective of the present work was to characterize the DLC films deposited by microwave ECR plasma CVD process under different bias voltages that will help in optimizing the deposition process parameters for deposition of DLC films on large area substrates and to explain the observed results by suit- 1567-1739/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.cap.2007.03.010 * Corresponding author. E-mail address: dspatil@barc.gov.in (D.S. Patil). www.elsevier.com/locate/cap www.kps.or.kr Current Applied Physics 8 (2008) 6–12