Group-III Nitride ETCH Selectivity IN BCl /Cl ICP Plasmas

Abstract

Patterning the group-111 nitrides has been challenging due to their strong bond energies and relatively inert chemical nature as compared to other compound semiconductors. Plasma etch processes have been used almost exclusively to pattern these films. The use of high-density plasma etch systems, including inductively coupled plasmas (ICP), has resulted in relatively high etch rates (often greater than 1 .O pdmin) with anisotropic profiles and smooth etch morphologies. However, the etch mechanism is often dominated by high ion bombardment energies which can minimize etch selectivity. The use of an ICP-generated BCl,/Cl, pl%sma has yielded a highly versatile GaN etch process with rates ranging from 100 to 8000 Mmin making this plasma chemistry a prime candidate for optimization of etch selectivity. In this study, we will report ICP etch rates and selectivities for GaN, AlN, and InN as a function of BCl,/Cl, flow ratios, cathode rf-power, and ICP-source power. GaN:InN and GaN:AlN etch selectivities were typically less than 7: 1 and showed the strongest dependence on flow ratio. This trend may be attributed to faster GaN etch rates observed at higher concentrations of atomic C1 which was monitored using optical emission spectroscopy (OES).

Conductivity Enhancement of PVD-WS2 Films Using Cl2-Plasma Treatment Followed by Sulfur-Vapor Annealing

“…9 these phenomena, we measured the dependence of the Cl 2plasma optical emission spectra intensity on the Cl 2 -plasma pressure by OES. In the previous study [35], [36], Cl radicals were obtained at approximately 837.6 and 842.8 nm, on the other hand in this study, a peak attributable to a Cl radical was confirmed as shown in Fig. 10.…”

Reactive ion etching of vertical GaN mesas by the addition of CH4to BCl3/H2/Ar inductively coupled plasma

“…It has been reported that the sloped GaN mesas with 60 • -70 • sidewall angles during high-density plasma etching under high-bias conditions result mainly from the recession of the mask edge due to overly strong physical sputtering [6][7][8]. It is therefore believed that the anisotropy improvement observed in this study is related to the deposition of the polymerized C-H species, which protect the Ni mask by retarding the sputter removal of the mask material.…”

“…RIE (reactive ion etching) techniques using high-density plasmas are mainly studied, such as the ECR (electron cyclotron resonance) and the ICP (inductively coupled plasma) techniques [1][2][3][4]. Works have also reported on the dry etching of the GaN mesas with vertical sidewalls [5][6][7][8], which are important for the fabrication of the reflection facets of laser diodes. The conventional cleaving may not be applied to GaN and related materials due to the hexagonal nature of their crystallographic structure.…”

Inductively coupled plasma etching of GaN using BCl3/Cl2chemistry and photoluminescence studies of the etched samples

“…Therefore, GaN etching based on chlorine chemistry is widely used in the fabrication of GaN based devices. Recently, Lee et al [14] and Shul et al [15] reported GaN etching using BCl 3 /Cl 2 plasma chemistry.…”