5 ms·

This is a bit off topic, but right out of grad-school, around forty years ago, I worked at Texas Instruments. The process control engineers would do their best,

by todd8 9y ago

This is a bit off topic, but right out of grad-school, around forty years ago, I worked at Texas Instruments. The process control engineers would do their best, but to some degree (at least back then), the yield for integrated circuits coming off the fabrication lines was very tricky to control. So parts would be tested and sorted by their performance as they came out. The components that could operate at hight frequency would end up as the more expensive part numbers. One front end line would end up making a mix of two part numbers determined by the testing. Through some kind of magic, the process would be tweaked by the engineers over time and the yields for the more expensive parts would often increase to the point where they wouldn't even end up with enough of the low cost parts so they would just stamp the low cost numbers on the chips that could actually run under much more demanding conditions.

anfractuosity 9y ago
Neat! Don't companies like Intel etc. still 'bin' chips into different products? Although I'm not sure if the reasons for binning now are different?
- TFortunato 9y ago
  Yep, absolutely still done, and for the same reason (in my experience), especially with Intel, and other companies who develop their own processes. What typically happens is that engineers do the best they can before release to model the process and experiment with building devices at different process "corners". This gives an idea of what the distribution of different electrical parameters will look like over the range of expected process variation (logic levels of FETs, sheet resistances, etc. etc.). Obviously this data is imperfect, because there are a TON of steps in a modern semiconductor process, and a TON of variables in each one. (For example, I worked on Ion Implanters, and we recorded hundreds of variables for our customers during the run, from vacuum levels, to gas dosages to voltages and currents in the various accelerator stages). As parent said, there is another group, who IMO are probably the original "big data" folks, usually called manufacturing or process engineers. They monitor the yields, binning and specific electrical measurements of all the wafers and parts coming off the line, along with process data for all the nanufacturing steps the wafer has gone through. These guys do the black magic of figuring out what needs to be tweaked in the process. At the higher levels it involves a mix of knowledge -- not only statistics and optimization, but also the semiconductor physics of how these parts actually operate, (since experiments can get expensive, you want to justify the knobs you are going to tweak!)
jeffwass 9y ago
Reminds me of the old joke about grouping parts into three bins : Military-spec, commercial grade, and Radio Shack.

by todd8 9y ago

anfractuosity 9y ago

Neat! Don't companies like Intel etc. still 'bin' chips into different products? Although I'm not sure if the reasons for binning now are different?

TFortunato 9y ago
Yep, absolutely still done, and for the same reason (in my experience), especially with Intel, and other companies who develop their own processes. What typically happens is that engineers do the best they can before release to model the process and experiment with building devices at different process "corners". This gives an idea of what the distribution of different electrical parameters will look like over the range of expected process variation (logic levels of FETs, sheet resistances, etc. etc.). Obviously this data is imperfect, because there are a TON of steps in a modern semiconductor process, and a TON of variables in each one. (For example, I worked on Ion Implanters, and we recorded hundreds of variables for our customers during the run, from vacuum levels, to gas dosages to voltages and currents in the various accelerator stages). As parent said, there is another group, who IMO are probably the original "big data" folks, usually called manufacturing or process engineers. They monitor the yields, binning and specific electrical measurements of all the wafers and parts coming off the line, along with process data for all the nanufacturing steps the wafer has gone through. These guys do the black magic of figuring out what needs to be tweaked in the process. At the higher levels it involves a mix of knowledge -- not only statistics and optimization, but also the semiconductor physics of how these parts actually operate, (since experiments can get expensive, you want to justify the knobs you are going to tweak!)

jeffwass 9y ago

Reminds me of the old joke about grouping parts into three bins : Military-spec, commercial grade, and Radio Shack.