AVS 49th International Symposium
    Plasma Science Wednesday Sessions
       Session PS+TF-WeP

Paper PS+TF-WeP18
A Study of Sapphire Etching Characteristics using Magnetized Inductively Coupled Plasmas

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Plasma Etching & Deposition
Presenter: C.H. Jeong, Sungkyunkwan University, Korea
Authors: C.H. Jeong, Sungkyunkwan University, Korea
D.W. Kim, Sungkyunkwan University, Korea
H.Y. Lee, Sungkyunkwan University, Korea
G.Y. Yeom, Sungkyunkwan University, Korea
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Sapphire substrate is attractive material because of its superior mechanical and corrosion property. It has been widely used as the substrate for GaN epitaxial growth and as insulating layer due to its high chemical stability, thermal stability, and dielectric property. On the other hand, it is known to be difficult for other processing such as etching and cutting due to the chemical and high thermal stability, the high hardness of sapphire itself, and the differences in the crystal orientation for GaN on sapphire. In this study, (0001) sapphire wafers were etched using magnetized inductively coupled plasmas(MICP) and their etch characteristics were compared with those by non-magnetized conventional inductively coupled plasmas(ICP). The use of Helmholtz type axial electromagnets around the chamber wall increased the sapphire etch rates while decreasing etch uniformity. By using both multi-dipole permanent magnets and axial electromagnets around the chamber wall, the etch uniformity could be improved while maintaining high sapphire etch rates. The sapphire etch rates close to 700nm/min which are higher than those etched using the conventional ICP could be obtained with optimized MICP conditions. The effects of etch parameters such as axial electromagnetic field(0 - 40Gauss), inductive power(600 - 1600Watts), and bias voltage(-100 - -300Volts) on the sapphire etch characteristic such as etch rates and etch selectivity over photoresist were investigated. The gas chemistry were maintained at 81%BCl@sub 3@/9%HBr/10%Ar, respectively. The etch mechanism of sapphire in MICP was investigated by plasma diagnostics using optical emission spectroscopy(OES) and quadrupole mass spectrometry(QMS) during the sapphire etching and by surface analysis using X-ray photoelectron spectroscopy(XPS) after the etching. The etch profile was observed as a function of process parameters by scanning electron microscopy(SEM) before and after etching the samples.