Silicon Wafer 125-200cm (5’’- 8’’) 0.5-0.8mm Initial doping ~ 1015 cm-3

Silicon Oxidation Si

Silicon Oxidation O2 SiO2 0.44tox Si

Silicon Epitaxial Growth p-type Si Epi Layer SiCl4 or SiH4 Gas with Impurities n-type Si

Silicon Etching Layer to be etched Mask Layer Apply Etch a,c: Etch selectivities b: Anisotropy

Ion Implantation Fixed Ions Dopant Ion from an accelerator Final Implanted Ion Location

Ion Diffusion High Concentration Low

Photolithography

Start with a Silicon Wafer Photolithography Start with a Silicon Wafer

Deposit a Layer of Silicon Dioxide Photolithography Deposit a Layer of Silicon Dioxide

We want to create this pattern Photolithography A “Mask” Layer We want to create this pattern on the silicon wafer

Spin a Photoresist Layer Photolithography Spin a Photoresist Layer

Uniform UV Light Illumination

Uniform UV Light Illumination

Uniform UV Light Illumination Negative Photoresist

Photolithography

Next we develop the photoresist Photolithography Next we develop the photoresist

Then we remove the photoresist Photolithography Then we remove the photoresist

Next, we want to implant the dopant ions Photolithography Next, we want to implant the dopant ions

Uniform Implantation of dopant ions Photolithography Uniform Implantation of dopant ions

Uniform Implantation of dopant ions Photolithography Uniform Implantation of dopant ions

Diffusion at High Temperatures Photolithography Diffusion at High Temperatures

Remove Silicon Dioxide Photolithography Remove Silicon Dioxide

Positive Photoresist Process Typically for depositing Polysilicon, but also for diffusions is small processes

Positive Photoresist Process Start with a Silicon Wafer

Positive Photoresist Process

Positive Photoresist Process

Positive Photoresist Process

Photolithography

Photolithography

Photolithography Develop the pattern

Photolithography After Etching

Photolithography Remove the Photoresist We have a polysilicon region