Semiconductor Quantum Dot Fabrication
In a semiconductor quantum dot device, precise control of electron and hole confinement is achieved by applying
voltages to metallic gates, forming potential landscapes that confine and concomitantly define the energy levels used for qubits.
These metallic gates, or "nanogates," must match the nanometer-scale dimensions of the confined particles.
To meet this exacting size requirement, the utilization of an electron-beam (E-beam) lithography system becomes
imperative. E-beam ligthography guarantees the creation of nanometer-sized pitches for these metallic gates,
ensuring their alignment with the stringent demands of quantum dot confinement.
The fabrication of a semiconductor quantum dot device involves several key steps.
It begins with etching a mesa and establishing an Ohmic contact. Next, a series of alignment markers are patterned,
and nanogates are meticulously deposited before being covered with oxide layers. The process ends with the deposition
of bonding pads.
A range of specialized equipment is essential to accomplish this intricate fabrication.
This includes an E-beam lithography system, a photolithography system, an electron-beam evaporator,
a reactive ion etcher (RIE), an atomic layer deposition system (ALD), a rapid thermal annealing system (RTA),
and various characterization tools like atomic force microscopes (AFM) and scanning electron microscopes (SEM).
Additionally, wet-etching and cleaning techniques are employed to ensure precision and cleanliness
throughout the process.