Steps in creating a transistor

Si Wafer

• thin, but not too thin

• round and flat shape

• single crystal

Oxidization

• Add oxygen either from O2 or H2O

• Create a layer of SiO2

  • this is ideal because Si/SiO2 have a clean bonding structure (no loose bonds)

• SiO2 is not water soluble

Spin Coating

• Add a layer of Photoresist

• Has three variables

  • Omega → the rotational speed of the disk

  • # of drops

  • time

Photolithography

• Exposes the Photoresist to light (Electromagnetic Wave)

• Chemically changes Photoresist

• E = hv (Planck’s constant)(frequency)

• Waves speed = (wavelength)(frequency)

• E = [(plancks constant)(wave speed)]/wavelength

Develop

Removes the section of Photoresist exposed to light67

Etch

• Wet etch → HF (danger)

• Dry etch → Plasma (pros: vert. sidewall, cons: complicated to do)

Strip the Photoresist

take off all of the photoresist

Dopants

• Two types:

  • diffusion

  • ion implantation

• converts the Si to either:

  • n-type (As, P)

  • p-type (B, Ga)

Spincoat

add another layer of Photoresist

Photolithography (Mask 2)

chemically change the photoresist

Develop

Remove the parts of the photoresist that were exposed

Metallization

Add a thin metallic layer onto your substrate

Strip the Photoresist

remove all your photoresist

Failure Analysis

investigate why your device functions/malfunctions