AVS 45th International Symposium
    Electronic Materials and Processing Division Tuesday Sessions
       Session EM+PS+SE-TuA

Paper EM+PS+SE-TuA10
Characteristics of Cl@sub 2@ -based Inductively Coupled Plasmas during the GaN Etching

Tuesday, November 3, 1998, 5:00 pm, Room 316

Session: Plasma Processing of Compound Semiconductors
Presenter: H.S. Kim, Sungkyunkwan University, Korea
Authors: H.S. Kim, Sungkyunkwan University, Korea
J.W. Jang, Sungkyunkwan University, Korea
Y.H. Lee, Sungkyunkwan University, Korea
G.Y. Yeom, Sungkyunkwan University, Korea
J.W. Lee, Samsung Advanced Institute of Technology, Korea
T.I. Kim, Samsung Advanced Institute of Technology, Korea
Correspondent: Click to Email
Planar inductively coupled Cl@sub 2@-based plasmas have been used to etch GaN and etch properties having smooth and nearly vertical etch profiles with the etch rates close to 850 nm/min could be obtained with Cl@sub 2@-rich gas combinations. To understand the effects of plasma conditions on the GaN etch properties, The quarupole mass spectrometry(QMS), optical emission spectroscopy(OES), and an electrostatic probe have been used. Especially, the quadrupole mass spectrometer system we used in the analysis of the plasmas was configured with ion optics, energy filter, and integral electron impact ion source for plasma diagnostics. Therefore, not only the radical densities but also positive and negative ion densities and their energy distributions were also measured. As process conditions used to study the effects of plasma characteristics on the GaN etch properties, Cl@sub 2@ was used as the main etch gas and Ar, BCl@sub 3@, and CH@sub 4@ were used as additive gases. Operational pressures were varied from 5mTorr to 30mTorr while other conditions such as inductive power, bias voltage, and substrate temperature were fixed at 600 watts, -120 volts, and 70 centigrade, respectively. The relative amounts of reactive ions (Cl@super +@, Cl@sub 2@@super +@, Cl@super -@, etc.), Ga-containing etch products(GaCl, GaCl@sub 2@, and GaCl@sub 3@ for Cl@sub 2@ plasma), and nitrogen-containing etch products ( N, N@sub 2@, NH@sub 3@, etc. ) were estimated by the plasma mass spectrometric measurements. The results showed that the enhancement of GaN etch rate was related to the increase of Cl radical and reactive ion such as Cl@super +@, Cl@sub 2@@super +@, etc. measured by the QMS and OES during the Cl@sub 2@-based inductively coupled plasma etching. Therefore, chemical reactions between Ga in GaN and Cl and Cl@sub 2@@super +@ from Cl@sub 2@, under the sufficient ion bombardments to break GaN bonds, appear to be important in the GaN etching. More detailed analysis of plasmas and their relation to GaN etching will be given in the presentation.