NANO 3D PRINTINGBy Brandan Shelley

photolithogrophy

With photolithography you start with a silicon disk. The silicon disk or wafer is first cleaned of any particles or imperfections.

The wafer is then blasted with a thin layer of silicon dioxide (SiO2)is deposited

the wafer is placed on a chuck and is given a second layer called photo resist, which is than spun until evenly distributed

the photo resist is different in situations where you want to leave a section or take it away.

Photo resist

With positive resist, the resist that is subjected to U.V. light changes the chemical structure of the exposed resist making itself more soluble. Once in cleaning the soluble resist and SiO2 is washed away leaving the none exposed SiO2.

With negative resist the resist that is NOT exposed to the U.V. light is more soluble once in cleaning the resist and SiO2 that was not exposed will be washed away .

Soft bake

once the silicon Wafer has been layered with the SiO2 and photo resist the wafer is then placed on to a heat pad to make the resist more photo sensitive

If over baked the solubility of the resist will be damaged

If under baked the U.V light will be unable to reach through the resist

Mask alignment

This is the step which goes along with the photo resist. Once your silicon wafer is prepped with the SiO2 and resist a mask or pattern of what you want in or remover from the resist is placed on a glass screen.

once the U.V. light hits the image the glass screen will angle the image on to the resist and make the image on the wafer smaller than the image on the mask.

Hard backing

Hard baking is the last step. After the wafer I developed the wafer gets a second bake.

The hard bake will secure the structure in place.

If under baked the SiO2 will be too wide and the etch not deep enough

If over baked the SiO2 will be thin and the etch too deep

Once backed and check for fallacies the wafer goes back through the same process until you get the end result of a transistor.

Nano print

With nano printing the same process of photolithography is occurring.

You start with a silicon wafer, clean it, then add the SiO2 and resist.

poerations Soft back the wafer to set the

resist . Then place in the developer.

Instead of having a mask or U.V. light the wafer will be burnt by a laser. The design is told through a computer to the laser and mirror. The laser is told where to fire and the mirror angles the beam of light on to a targeted area.

the beam still needs to bee smaller so the mirror directs the laser through multiple layers of glass that minimizes the laser to allow nano scale printing.

Once you have finiched printion you will hard back the wafer and to suport the SiO2 structure thaan the prices will stat over with the deposit of SiO2 and photo resist

Ted talk https://

www.youtube.com/watch?feature=player_detailpage&v=2V4DwZmQenY

Work sited

Google. Com / images Photolithography, ece. Gatech., web, ND,

29 nov, 2014 https://

www.youtube.com/watch?feature=player_detailpage&v=2V4DwZmQenY