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I am curious about how analog chips are produced. I know that the most advanced logic are made with many rounds of deposition, etching, lithography, etc, but I haven't seen much material about how analog chips are produced. I checked the website of the largest lithography company, ASML, and they say their customers can be divided entirely into Logic and Memory (both digital). Do analog chips not need lithography or do analog producers have older litho/manufacturing equipment that suffices?

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  • \$\begingroup\$ They all use transistors so, same/similar process in general. \$\endgroup\$
    – Andy aka
    Jul 31, 2023 at 16:59
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    \$\begingroup\$ Do a search on mit opencourseware IC lithography and find a course or two. Go through them. Follow up with new keywords you find, too. If you really care about this, you'll find what you need from that process. \$\endgroup\$ Jul 31, 2023 at 17:09
  • \$\begingroup\$ @Andyaka Hi Andy, that would make sense, but then why doesn't ASML list any analog use cases for their products? Especially given that they pretty much own the market for all litho machines. \$\endgroup\$
    – johnf42
    Jul 31, 2023 at 17:28
  • \$\begingroup\$ Because, as you say, their customers can be divided entirely into Logic and Memory (both digital). Look at the market for custom analogue chips and compare it. \$\endgroup\$
    – Andy aka
    Jul 31, 2023 at 17:43
  • \$\begingroup\$ You're probably looking at equipment made for leading edge logic nodes rather than analog. Look harder and you can probably find similar material about analog too. \$\endgroup\$ Jul 31, 2023 at 18:21

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These are the dies of the digital SN74AHC1G00 and the analog LMV321:

SN74AHC1G00 die LMV321 die
Source: Zeptobars SN74AHC1G00 LMV321

In theory, they are of similar complexity, and are mostly made of a bunch of transistors. So they could be made with the same manufacturing equipment.

In practice, however, there are differences:

  • Modern digital chips can have billions of transistors, so they need to be made on a modern, expensive process that can etch extremely fine structures. Analog chips do not need such complexity and are generally made with older processes. (But analog manufacturers will switch to a newer process if it is more efficient.)
  • Analog chips usually include resistors and capacitors, and might need additional manufacturing steps such as laser calibration. So the largest manufacturers of analog chips have their own fabs (this is somewhat more common than with digital chips).

But these are not fundamental differences. Many chips are called "mixed-signal" and combine analog and digital parts, and there are many fabless design houses that will create custom analog or mixed-signal chips.

Regarding ASML, their marketing emphasizes the bleeding-edge stuff, but they will happily take your money in exchange for more mature equipment usually used for analog chips.

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  • \$\begingroup\$ Thanks! If ASML is selling older DUV machines for mature analog nodes, however, why aren't they classifying it as such in their reporting? It all makes sense technologically, but it's confusing me in their financial statements. For example, the word analog doesn't even appear once in their latest annual report. Is there any way for an analog chip to be interpreted as logic? \$\endgroup\$
    – johnf42
    Aug 1, 2023 at 7:50
  • \$\begingroup\$ These older DUV machines are not exclusively used for analog chips, and I do not know if ASML knows what their customers will actually use them for. \$\endgroup\$
    – CL.
    Aug 1, 2023 at 8:34

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