The second chip (Circuit 2) shown is an old memory device. The chip shown here is the type of microchip associated with Intel © and Motorola ©. The old memory device is much larger than the other therefore can't handle as much information. The smaller chip is made using techniques that allows for smaller components, such as capacitors and transistors. The smaller the components, the more that can fit in a given area and the faster the device will run.

       A general overview on the process involved in fabricating such small components on a single chip is as follows:

1. A silicon substrate is cut from a single crystal ingot of silicon. The substrates are on the order of millimeters. The substrate is cut such that it has a particular crystallographic orientation. A substrate from a single crystal is used to alleviate problems that occur due to defects, i.e. grain boundaries.

2. Lithography is then used to create the designs of the components on the substrate.
         - The substrate is coated with a layer of photoresist.
         - The pattern is made by exposing certain areas with radiation, such             as UV. There are two options, positive photoresist and negative
            resist
         - The leftover resist is then etched away, usually with HF acid

3. Metal is deposited over the pattern. Usual techniques include chemical vapor deposition (CVD) or plasma vapor deposition (PVD).

     Steps 2 and 3 are repeated many times to create the complete microchip. Many chips are made at once on the substrate, usually 6 - 8 inches in diameter.

     Careful control of the environment is maintained. One parameter is that all work be done in a clean room. A clean room is defined as a room that most of the particles are removed from the room. Particles must be at a minimum because even the smallest particle can ruin the chip. The workers must wear gear that looks like something HAZMAT would wear because one of the most common particles is human skin that has shed off.

     The temperatures and pressures are carefully monitored during the entire process. The temperatures are monitored so that appropriate growth or attachment of the layers can be achieved with little deviation from the design specifications. Pressure must be maintained also such that the materials don't evaporate or unwanted ones deposit.

Acknowledgements:
          -      Dr. Mayer
        -     The Staff of the Goldwater Basement Facilities

                                                                                           ~A.Trees~