Etch product identification during - RIE of InP using mass spectrometry

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Abstract
The composition of the plasma phase during InP RIE in - is investigated in detail by quadrupole mass spectrometry for the identification of the In and P etching reaction products. The plasma phase species are analysed in detail by means of neutral and positive ion detection during the InP - RIE process. The complexity of the gas phase reactions in the - discharge is shown by the formation of various molecules and positive ions. In the presence of InP on the RF driven electrode, and are evidenced as the neutral products of P present in the plasma phase. But contributes to about 5% of the total neutral P plasma species, clearly demonstrating phosphine as the major etch product of P. No organoindium compounds of general formulation with x = 0 - 3 can be detected as neutrals. However organoindium compounds are still regarded as the etch product of indium since and positive ions are evidenced by mass spectrometric sampling of ionic species during the - RIE process of InP. A semi-quantitative analysis effectively shows that these In positive ions probably originate from the direct ionization of the indium etch product, probably an organoindium compound. In contrast, it is shown that the phosphine positive ions mostly result from secondary ion - molecule reactions in the plasma phase between , the major P neutral product, and the positive ions of the discharge. As a results these ions cannot be confidently used to determine the P etch products and to monitor the P etching process.