Episode Synopsis "A fourth photographic emulsion is patterned"

Listen "A fourth photographic emulsion is patterned"

More episodes of the podcast Making an Integrated Circuit

• Let's go inside an Intel 4004 microprocessor to see an individual transistor
• To make this transistor, first oxide then nitride layers are grown
• A shadow mask then exposes a photographic emulsion
• Exposed nitride is then etched away
• Oxygen reacts with the Si to grow more oxide
• By heating in silane, polycrystal Si is then grown
• A stripe is exposed in a second photographic emulsion
• Exposed polycrystal Si is etched away leaving the transistor gate
• Phosphorus ions then penetrate thin oxide to create the source and drain
• Heating in oxygen grows an insulating coat on the gate
• A third photographic emulsion defines windows above the source and drain
• Openings are then etched in the exposed oxide
• Metal is sprayed on to the surface
• A fourth photographic emulsion is patterned
• Unwanted metal is etched away completing the transistor
• And finally, here is the circuit symbol for the transistor
• This podcast is drawn from the Virtual Lab presentations of WeCanFigureThisOut.org. The copyrighted material of this site was developed under funding from National Science Foundation CCLI, NIRT, MRSEC and NUE programs. This project is led by John C. Bean
• All of the scenes together