NanoFab Trainer

Nick Reedernick.reeder@sinclair.edu

June 28, 2012

NanoFab Trainer

• Educational tool that lets user see the results of performing sequences of basic nano-fabrication operations on a silicon (Si) wafer.

• Runs under Windows operating system.• Written in LabVIEW 2009; requires LabVIEW

2009 Run-Time Engine (free download at http://joule.ni.com/nidu/cds/view/p/id/1600/lang/en).

User Operations

• Ion implantation (“doping”)• Thermal oxidation• Photolithography• Depositing layers of material• Removing material

Ion Implantation

• Modifies the electrical characteristics of the silicon wafer. Such modification is the key technique underlying the operation of semiconductor devices (diodes, transistors, thyristors).

• Implanting boron results in “p-type” doping.• Implanting phosphorus results in “n-type”

doping.

Example: Fabricating a MOSFET

• MOSFET = Metal-oxide-semiconductor field effect transistor

Thermal oxidation

• Grows a layer of silicon dioxide (SiO2) on the wafer surface.

• Key properties of SiO2:– Impervious to ion implantation.– Can be etched away by immersion in hydrofluoric

acid (HF), which does not etch silicon.

Photolithography

• Steps in photolithography:– Spin-coat photoresist.– Create and place mask. Mask defines which

areas will be exposed to UV light and which areas will be shaded.

– Expose with UV light.– “Develop” the photoresist: UV-exposed areas are

removed, while shaded areas remain.• Wikipedia http://en.wikipedia.org/wiki/Photolithography

Depositing Layers

• Methods of depositing layers of material– Electron-beam evaporation– Chemical vapor deposition (CVD)– Sputtering

• The materials deposited may be metals, dielectrics, or semiconductors.

Removing material

• Methods of removing material – Wet etching• Low-tech• Immerse wafer in a bath of liquid acid or solvent

– Dry etching• High-tech• Expose wafer to plasma beam

Other Features of Trainer• Maintains history of user operations.• Will track cost, time, and quality of user

operations.• “Tutorial” page will provide photos and

videos of operations being performed in the lab, along with text explaining theory.