Electron cyclotron resonance (ECR) plasma etching of p- and n-In0.49Ga0.51P layers in Al-free laser structures is studied based on BCl3/N-2 gas mixture. Laser reflectometry is used for the in situ etching analysis. Strong etching rate discrepancies are found for the same material whether inserted in multilayer laser structures or in single calibration layers. Strong etching dependence with growth conditions and beryllium concentration is found. Great reduction in etching rate is observed near p(++)GaAs/p(++)In(0.49)Ga(0.51)P interfaces depending on growth conditions. These results are explained by a 200 Angstrom beryllium diffusion in the In0.49Ga0.51P material with subsequent formation of Be3P2 clusters in p-In0.49Ga0.51P during growth.