Subsections


C. Process parameters


C.1 Cleaning process

C.1.0.1 Cleaning before photo-lithography

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item immersion (with ...
...ot plate drying, $170^\circ$C, 5 min
\item visual inspection.
\end{itemize}}$

C.1.0.2 Cleaning before metallization: deoxidation of GaAs

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item immersion in HCl...
...se in deionized (DI) water, 2 min
\item nitrogen blow drying.
\end{itemize}}$

C.1.0.3 Plasma cleaning after photo-lithography

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item Oxygen plasma et...
...~W
\item time 20~s
\end{itemize}
\item visual inspection.
\end{itemize}}$

C.1.0.4 Resist removal after etch process

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item immersion (with ...
..., 1 min
\item nitrogen blow drying
\item visual inspection.
\end{itemize}}$

C.1.0.5 ECR-Chamber cleaning before plasma-etch

$\textstyle \parbox{\textwidth}{
\begin{itemize}
\item ECR-Chamber cleaning S...
...
14~ml/min cooling circuit
\item time 20~min
\end{itemize}
\end{itemize}}$

$\textstyle \parbox{\textwidth}{
\begin{itemize}
\item ECR-Chamber cleaning S...
...
14~ml/min cooling circuit
\item time 10~min
\end{itemize}
\end{itemize}}$


C.2 Lithography processes

C.2.0.1 Edge removal - lacquering AZ 5214

$\textstyle \parbox{\textwidth}{
\begin{itemize}
\item exposure UV 365 / 7 mW...
...1), 45 s
\item rinse in DI water
\item nitrogen blow drying
\end{itemize}}$

C.2.0.2 Positive process - lacquering AZ 5214

$\textstyle \parbox{\textwidth}{
\begin{itemize}
\item \textit{optional:} adh...
... 45-50~s
\item rinse in DI water
\item nitrogen blow drying
\end{itemize}}$

C.2.0.3 Positive process - lacquering AZ 4564, resist layer for plating air-bridges

$\textstyle \parbox{\textwidth}{
\begin{itemize}
\item AZ 45644 resist spinni...
...gen blow drying
\item post bake in oven, $100^\circ$C, 30 min
\end{itemize}}$

C.2.0.4 Image-reversal process - lacquering AZ 5214, simple resist layer

$\textstyle \parbox{\textwidth}{
\begin{itemize}
\item AZ 5214 resist spinnin...
...1), 23 s
\item rinse in DI water
\item nitrogen blow drying
\end{itemize}}$

C.2.0.5 Negative process - lacquering PMMA for E-Beam lithography

$\textstyle \parbox{\textwidth}{ \small
\begin{itemize}
\item PMMA 600 resist...
...5, 150 s
\item rinse in propanol
\item nitrogen blow drying
\end{itemize}}$

C.2.0.6 Image-reversal process - lacquering AZ 5214, double resist layer

$\textstyle \parbox{\textwidth}{
\begin{itemize}
\item AZ 5214 resist spinnin...
...1), 26 s
\item rinse in DI water
\item nitrogen blow drying
\end{itemize}}$

C.2.0.7 Negative process - lacquering Polyamide (Durimide 7510)

$\textstyle \parbox{\textwidth}{
\hspace{1cm} \textbf{Lithography}
\begin{item...
...tem development stop in 2-propanol
\item nitrogen blow drying
\end{itemize}}$

$\textstyle \parbox{\textwidth}{
\hspace{1cm} \textbf{Polyamide hardening in va...
...irc$C, slope $-150^\circ$C/h
\item oven with nitrogen venting
\end{itemize}}$


C.3 Wet-chemical etching processes

C.3.0.1 GaAs etching with sulfuric acid for substrate removal

$\textstyle \parbox{\textwidth}{ \small
\begin{itemize}
\item H$_2$SO$_4$\ : ...
...m/min}$
\item rinse in DI water,
\item nitrogen blow drying
\end{itemize}}$

C.3.0.2 GaAs etching with sulfuric acid for mesa isolation

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item H$_2$SO$_4$\ : H...
...m/min}$
\item rinse in DI water,
\item nitrogen blow drying
\end{itemize}}$

C.3.0.3 Selective Etching of GaAs over $ Al_{0.6}Ga_{0.4}As$

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item C$_6$H$_8$O$_7$\...
...m/min}$
\item rinse in DI water,
\item nitrogen blow drying
\end{itemize}}$

C.3.0.4 Selective Etching of $ Al_{0.6}Ga_{0.4}As$ over GaAs

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item HF (48\%) : H$_2...
...I water
\item rinse in DI water,
\item nitrogen blow drying
\end{itemize}}$

C.3.0.5 Etching process for nickel removal

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item 5 g FeCl$_3$\ : ...
...\ 4 min
\item rinse in DI water,
\item nitrogen blow drying
\end{itemize}}$

C.3.0.6 Etching process for titan removal

$\textstyle \parbox{\textwidth}{ \small
\begin{itemize}
\item AF 91-9 [(NH$_4...
...tation)
\item rinse in DI water,
\item nitrogen blow drying
\end{itemize}}$


C.4 Plasma-etching processes

C.4.0.1 ECR-RIE process for GaAs, AlGaAs mesas

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item Cl$_2$\ flux 8~m...
...item cooling $0^\circ$C, with He flow 14~ml/min cooling circuit
\end{itemize}}$

C.4.0.2 ECR-RIE process for GaN mesas

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item Cl$_2$\ flux 20~...
...item cooling $2^\circ$C, with He flow 14~ml/min cooling circuit
\end{itemize}}$

C.4.0.3 ECR-RIE process for GaN nanocolumns

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item Cl$_2$\ flux 16~...
...n cooling circuit
\item (optional) 1 min RF on / 1 min RF off
\end{itemize}}$

C.4.0.4 RIE process for Polyimide (Durimide 7510)

$\textstyle \parbox{\textwidth}{ \small
\begin{itemize}
\item O$_2$-Flus 30~m...
...us 1~ml/min
\item process pressure 1 mbar
\item power 100~W
\end{itemize}}$


C.5 Metallization processes

C.5.0.1 Ohmic contacts (for GaAs)

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item 20 nm Ge / 15 nm Ni / 200 nm Au
\end{itemize}}$

C.5.0.2 Ohmic contacts (for GaN)

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item 35 nm Ti / 200 nm Al / 50 Ni / 200 nm Au
\end{itemize}}$

C.5.0.3 Bond pads

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item 30 nm Ti / 600 nm Au, rotating evaporation
\end{itemize}}$

C.5.0.4 Bond pads for polyamide process

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item 50 nm Ti / 50 nm Au / 50 nm Ti / 650 nm Au,
rotating evaporation
\end{itemize}}$

C.5.0.5 Air-bridge seed layer

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item 1 nm Cr / 90 nm Au \\ or
\item 80 nm Au /10 nm Ti
\end{itemize}}$

C.5.0.6 Lift-Off process

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item immersion (with ...
..., 2 min
\item nitrogen blow drying
\item visual inspection.
\end{itemize}}$

C.5.0.7 Annealing of Ge/Ni/Au metallization in RTP oven

$\textstyle \parbox{\textwidth}{ \hspace
{1cm} \textbf{temperature profile}\sma...
...\item cool down to room temperature, 240 s, N$_2$\ flux 5 l/min
\end{itemize}}$

C.5.0.8 Annealing of Ti/Al/Ni/Au metallization in RTP oven

$\textstyle \parbox{\textwidth}{ \hspace
{1cm} \textbf{temperature profile}\sma...
...\item cool down to room temperature, 240 s, N$_2$\ flux 5 l/min
\end{itemize}}$

C.5.0.9 Gold galvanic plating

$\textstyle \parbox{\textwidth}{\small
\begin{itemize}
\item plating bath prep...
...m/min}$
\item rinse in DI water,
\item nitrogen blow drying
\end{itemize}}$

simone montanari 2005-08-02