A new elegant technique for polishing CVD diamond films

• Published in: Diamond and related materials Vol. 12; no. 8; pp. 1411 - 1416
• Main Authors: Tang, C.J., Neves, A.J., Fernandes, A.J.S., Grácio, J., Ali, N.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-08-2003; Elsevier
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Microwave plasma CVD; Physics; Polishing; Polishing CVD diamond; Polycrystalline film; Surface roughness; Surface treatments; Surface roughness; Polycrystalline film; Microwave plasma CVD; Polishing CVD diamond; Abrasion; Mechanical polishing; Synthetic mineral; Thick films; Diamonds; Roughness; Polycrystals; Surface treatments; Experimental study; Coatings; CVD; Nonmetals; PECVD
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(03)00169-9

It is well known that the columnar growth nature of CVD diamond results in a very rough growth surface and the surface roughness steeply increases with film thickness, especially for thick CVD diamond films. In this paper, we report the successful implementation of a new elegant technique for polishing thick polycrystalline CVD diamond films at high polishing rate of up to 10 μm/h. This technique involves polishing the as-grown polycrystalline diamond films with another thick as-grown polycrystalline diamond film, which acts as a polishing abrasive. Two types of diamond films were prepared using microwave plasma CVD and then polished for 2 h using the new polishing technique. A stylus profilometer, scanning electron microscopy and Fourier transform infrared spectroscopy were used to measure the surface roughness, characterize morphology and optical transmission of the samples before and after polishing, respectively. By polishing, thickness of 20–30 μm was removed from the top surface, and the mean surface roughness
R
a of the films reduced significantly, e.g. for one film
R
a reduced initially from 5.2 to 1.35 μm and the other from 3.2 to 0.55 μm. The principal advantages of this new polishing technique are simplicity, flexibility and time saving. This simple method can serve as ‘rough chipping’ to quickly remove the rough top surface and then combine with conventional polishing methods for precision machining to further reduce the surface roughness to a specific desired degree.