Y. Feurprier et al., SURFACE MODIFICATION AND ETCH PRODUCT DETECTION DURING REACTIVE ION ETCHING IN INP IN CH4-H-2 PLASMA, Plasma sources science & technology, 6(3), 1997, pp. 334-342
A detailed plasma-surface interaction study has been conducted using m
ass spectrometry and optical emission spectroscopy for the plasma char
acterization, and quasi in situ XPS analyses to central the surface ch
emistry modifications. The experimental results clearly evidence the d
ifferent etching behaviour of In and P in the CH4-H-2 plasma environme
nt. A signature of the In and P etching mechanisms is available from t
he diagnostic of the plasma phase through the detection of phosphine a
s the major etching product of P and of excited In atoms related to th
e In etching reaction. The observation of the In emission line at 451.
1 nm indicates a probable decomposition in the discharge of the organo
indium compound which is regarded as the etch product of the group III
element. XPS reveals the presence of P-H, C-In, In-In-C and In-In-P a
s surface species, and allows us to quantify precisely the P surface d
epletion. A time dependent etching mechanism is shown, first suggested
by the etched thickness measurements and further confirmed by both et
ch product signal intensity and surface stoichiometry evolution with t
he plasma exposure time. Mass spectrometric PH3+ signal and In emissi
on line intensities monitored as a function of time indicate that the
in etching mechanism is responsible for this situation, It is conclude
d that the reactive ion etching of InP is under the control of the rem
oval mechanism of In. The combination of surface analysis and plasma d
iagnostics is shown to be capable of providing an understanding of the
plasma-surface interaction.