AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoM

Paper TF-MoM2
Time-resolved Study of C@sub x@N@sub y@ Growth by Means of Fourier Transform Infrared Reflection Spectroscopy

Monday, October 25, 1999, 8:40 am, Room 615

Session: Fundamentals of PECVD
Presenter: A. de Graaf, Eindhoven University of Technology, The Netherlands
Authors: A. de Graaf, Eindhoven University of Technology, The Netherlands
B. Schreur, Eindhoven University of Technology, The Netherlands
M.C.M. van de Sanden, Eindhoven University of Technology, The Netherlands
D.C. Schram, Eindhoven University of Technology, The Netherlands
Correspondent: Click to Email
Fourier transform infrared (FTIR) reflection spectroscopy is used to study the composition of carbon nitride (C@sub x@N@sub y@) films in situ during the early stages of growth and during etching. The C@sub x@N@sub y@ films are deposited from a thermal Ar/N@sub 2@ plasma expanding through a graphite nozzle. The graphite is chemically etched leading to strong CN emission both at the nozzle exit and at the substrate level 65 cm downstream. The observation of C@sub 2@N@sub 2@ in the mass spectrometer gives further support to the idea that CN radicals are formed during deposition. In order to measure small reflection changes on a (sub)monolayer level and on a short enough time scale, a special substrate has been developed which enhances the IR absorption considerably at a specific wavelength. With this substrate the evolution of the different bonds (sp@super 1@, sp@super 2@ and sp@super 3@ C-N) in the film can be followed. The results show a relative increased absorption of the sp@super 1@ C-N bond during initial growth as compared to the absorption in the bulk material. This strongly suggests that CN radicals are indeed involved in the deposition. After film growth the absorption of sp@super 1@ C-N bonds decreases while the absorption of sp@super 2@ C-N bonds increases. Etching of the C@sub x@N@sub y@ films by an expanding Ar/N@sub 2@ or Ar/O@sub 2@ plasma also shows a different response in the absorption signal of sp@super 1@ C-N as compared to sp@super 2@ C-N. The optical constants of the material and growth rate are derived from an optical model and are correlated to in situ ellipsometry measurements performed simultaneously. Based on these findings a tentative growth model is presented. In a next step this model will be extended to describe deposition at different substrate temperatures and bias voltages.