|
In this thesis, we report the reactive ion etching of InGaP and
InP (including undoped, p and n+ type ) in CH4/H2 mixtures. The
etch rate was measured as a function of etch time, rf power
density, methane fraction,chamber pressure, and total flow
rate. The relative fraction of methane and hydrogen is the most
important parameter that controls the etch rate, polymer
deposition rate, surface stoichiometry, and anisotropy. Both
InP and InGaP have the maximum etch rate at CH4/H2 = 1 : 3 (
CH4 % = 25 % ) when the other parameters were kept constant.
The InP etch rate is found to increase nearly linearly with rf
power density over the range studied. The etch rates of InP and
InGaP, up to 145 and 40 nm/min, are obtained respectively.
Generally, the trend of etch rate is : InP ( n = 5.9 * 1015
cm-3 ) > p-InP ( n = 5 * 1018 cm-3, Zn doped ) ~ n+-InP ( n = 3
* 1018 cm-3, Sn doped ) >> InGaP ( n = 1 * 1018 cm-3, Si doped
). The average etch rate of InP is about 3 * 6 times faster
than that of InGaP. There are many measurements, such as SEM,
SIMS, AES, and XPS have been made to check the thickness of the
epitaxial layer, and analyze the surface morphology and
chemistry after RIE.
|