In situ etching depth monitoring for reactive ion etching of InGaAs(P)/InP heterostructures by ellipsometry

In situ ellipsometry at a wavelength of 1300 nm is used to control the etching depth in InGaAs(P)/InP heterostructures. A rotating analyzer ellipsometer, adapted to a parallel-plate reactor for reactive ion etching (RIE), monitors the decreasing layer thickness during the dry etching process. The momentary etching depth is determined with an accuracy of +or-10 nm. Using a methane/hydrogen gas mixture for RIE a characteristic surface modification of the semiconductor material is observed