Comparison of dry etching of AlGaAs and InGaP in a planar inductively coupled $BCl3$ plasma

We studied dry etching of AlGaAs and InGaP in a planar inductively coupled $BCl3$ plasma. The process parameters were planar ICP source power (0–500 W), reactive ion etching (RIE) chuck power (0–150 W), and chamber pressure (5–15 mTorr). The process results were characterized in terms of etch rate, surface morphology, and surface roughness. The planar inductively coupled $BCl3$ plasmas were also monitored with in situ optical emission spectroscopy (OES). $BCl3$ planar inductively coupled process (ICP) etching of AlGaAs showed very vertical sidewall, clean and smooth surface, while that of InGaP showed somewhat rough surface after etching. Etch rates of AlGaAs were generally higher than those of InGaP in the planar $BCl3$ ICP etching. It indicated that $InClX$ byproducts had relatively low volatility during InGaP etching in the planar inductively $BCl3$ plasmas. Increase of ICP source power and RIE chuck power strongly raised etch rates of both AlGaAs and InGaP. That of pressure decreased etch rate of both materials. OES data showed that emission intensity of the planar $BCl3$ ICP was a strong function of ICP source power and chamber pressure, while it was almost independent of RIE chuck power.