Microelectronic Process Integration


Defining the actual microelectronic fabrication process to create a device is known as process integration. Process integration involves combining all of the individual silicon processing steps with the appropriate masks and equipment settings to create a functioning device. The simplified process flow to create an integrated resistor (shown below) provides an indication of the methods in which these steps may be combined.

Start with Silicon Wafer

Dirty Wafer


Wet Clean the Wafer

Clean Wafer


Oxidize the Wafer in Diffusion Furnace

Blanket Oxide


Coat, Expose, and Develop Photoresist

Implant Lithography


Dry Etch Oxide, Stop on Silicon

Dry Etch Oxide, Stop in Silicon


Ion Implantation into Silicon

Implant Silicon


Etch Photoresist and Oxide

Diffusion in Silicon


Oxidize the Wafer in Diffusion Furnace

Oxidized Diffusion


Coat, Expose, and Develop Photoresist

Lithography Contact Cut


Coat, Expose, and Develop Photoresist

Etch Contact Cuts


Remove Photoresist

Strip Contact Cuts


Deposit Metal by Sputtering or Evaporation

Metal Deposition


Coat, Expose, and Develop Photoresist

Metal Lithography


Dry Etch Metal, Stop on SiO2

Metal Etch


Remove Photoresist

Metal PR Strip


You have now created a diffused resistor in silicon. Electrical current travels through the metal and into the silicon, which has been modified to a desired conductivity by the implantation of dopant ions. The current then runs through the doped silicon and out the opposite metal contact.

Though modern devices are considerably more complex, the same basic patterning and processing steps are used in their fabrication. For an added challenge, consider building an integrated resistor or other device using a Lego model.


LEGO Diffused Resistor

LEGO Diffused Resistor

Basic instructions for a Lego diffused resistor are included here. Color code: green=silicon; orange=doped silicon; blue=oxide; red=metal. View required parts list here.