The Effect of the Native Oxide on Mask Undercutting of V‐Grooves Etched into (100) InP Surfaces Using an SiN x Mask

An investigation has been undertaken on the effect of mask undercutting when using chemical etching techniques to produce various V‐groove features on a (100) InP substrate. SiNx masking films were deposited on two types of sample surface. In one case the surface was covered with a naturally occurring oxide; in the other case the oxide was desorbed in a molecular beam epitaxy system and the sample was subsequently transferred in vacuum to an electron cyclotron resonance chemical vapor deposition chamber. Reduced mask undercutting is obtained for cases involving the oxide‐free SiNx/InP interfaces, demonstrating the importance of the InP oxide in the undercutting.