Process monitoring and control of low temperature reactively sputtered A1N

Scott R. Kirkpatrick, Suzanne L. Rohde, Dorina M. Mihut, Mary L. Kurruppu, John R. Swanson, Dan Thomson, John A. Woollam

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


In this article we investigate the potential of controlling the sputtering of AlN using a combination of techniques such as target voltage analysis and ellipsometry. The growth processes for A1N are studied simultaneously at the target, as well as the substrate. Iterative optimization can be replaced almost entirely with in situ, real time process control/monitoring; reducing development time of a new process by more than an order of magnitude. To demonstrate this, A1N was reactively sputtered using an unbalanced magnetron onto 2024-A1, (100)Si, and stainless steel substrates and monitored by an in situ ellipsometer which indicated the index of refraction 'n' values of approximately 2.09-2.16 in the range 1.6-3 eV. Differing ion intensities were achieved by varying the bias on the substrate, and the effects were studied by X-ray diffraction, and profilometry. X-ray diffraction confirmed formation of hexagonal aluminum nitride with a preferred orientation of (001) by using a constant bias current substrate instead of a constant bias voltage. The profilometry tests indicated deposition rates of 38 nm/min. A detailed analysis of aluminum nitride formation with varying nitrogen flow was compared with the ellipsometric and target voltage versus nitrogen flow data to determine the optimal N2 flow rate. The sputtering rate of A1N was minimally 28% of the metal sputtering rate.

Original languageEnglish (US)
Pages (from-to)16-20
Number of pages5
JournalThin Solid Films
Issue number1-2
StatePublished - Nov 2 1998


  • Ellipsometry
  • Low temperature reactively sputtered A1N
  • Target voltage analysis

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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