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9.5.1: Introduction to IC Manufacturing Technology

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    89981
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    It would probably be interesting to spend a little time seeing how integrated circuits are made. This chapter will be long on description, and rather short on equations (yay!). This is not to say that there is not a lot of analytical work in the IC fabrication process. It's just that things get very complicated in a hurry, and so we probably are better off just looking at most processes from a qualitative point of view.

    Let's start out by taking a look at the state of the industry, and remark on a few trends. Figure \(\PageIndex{1}\) is a plot of IC sales in the United States over the past 30 years. This might not be a bad field to get into! Maybe there will be a job or two out there when you are ready to graduate.

    Between 1960 and 2000, IC sales in billions of dollars have grown fairly steadily from less than 0.01 to 100.
    Figure \(\PageIndex{1}\): Growth of IC business in the U.S.

    There has been a steady shift away from bipolar technology to MOS as is shown in Figure \(\PageIndex{2}\). Currently, about 90% of the market is composed of MOS devices, and only about 10% of bipolar. This is likely to be the case for some time to come. The change in slope, where MOS starts taking over from bipolar at a more rapid rate about 1987, is when CMOS technology really started to come into heavy use. At that point, bipolar TTL logic essentially faded to zero.

    Between 1980 and 2000, MOS devices go from making up roughly half of IC business compared to bipolar transistors to roughly 90%. This change increases more rapidly after 1987.
    Figure \(\PageIndex{2}\): Percentage of IC sales made up by MOS versus bipolar technologies

    As you probably are aware, devices have been getting smaller and smaller, and chips have been getting bigger and bigger with time. A most impressive plot is one which shows the number of components/chip as a function of time:

    Between 1970 and 1980, the number of components per chip increased from 1000 to nearly 100,000. From 1980 to 2000, the number of components per chip increased to just over 1 billion.
    Figure \(\PageIndex{3}\): Number of transistors per chip over times

    One of the main drivers for this has been feature size, which shows the same nearly exponential behavior as components/chip. This is plotted in Figure for your education. What is interesting to note about this is that certain "doom sayers" have been predicting an abrupt halt to this curve for some time now. It stands to reason that you can not image something which is finer than \(\lambda\), the wavelength of the light you use to project it with. However, by going to the ultraviolet, and using a variety of image enhancing techniques, lithographic engineers continue to be able to make finer and finer structures.

    From 1960 to 1990, the minimum feature size in micrometers decreases from 50 to roughly 1. From 1990 to 2000, this minimum size decreases to slightly over 0.1.
    Figure \(\PageIndex{4}\): Feature size with time

    This page titled 9.5.1: Introduction to IC Manufacturing Technology is shared under a CC BY-NC-SA 1.0 license and was authored, remixed, and/or curated by Bill Wilson via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.