We developed an optimized inductively coupled plasma (ICP) etching process to produce GaAs pyramidal corrugated quantum well infrared photodetector focal plane arrays. A statistically-designed experiment was performed to optimize the etching parameters. The resulting parameters are discussed in terms of the effect on the etching rate and profile. This process uses a small amount of mask corrosion and the control of the etching mask gap to give a 45-50 degree V-groove etching profile, which is independent on the crystal orientation of GaAs. In the etching development, scanning electron microscope (SEM) was used to observe the surface morphology and the pattern profile. In addition, X-ray photoelectron spectroscopy (XPS) was utilized to obtain the elemental composition and the contamination of the etching surface. It is found that extremely small stoichiometric change and surface damage of the etching surface can be achieved while keeping relatively high etching rate and ~45 degree V-groove etching profile. This etching process is applied to the fabrication of pyramidal C-QWIP FPAs, which is expected to have better performance than the regular prism-shaped C-QWIPs according to electromagnetic (EM) modeling. The expected results will be verified by optical and electrical measurements. In addition to infrared detectors, this process technology can also be applied to GaAs V-groove solar cell, quantum wire light-emitting diodes, quantum wire lasers, and other GaAs –based devices.