Front end of line
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The front-end-of-line (FEOL) is the first portion of IC fabrication where the individual components (transistors, capacitors, resistors, etc.) are patterned in the semiconductor.[1] FEOL generally covers everything up to (but not including) the deposition of metal interconnect layers.[2]
For the CMOS process, FEOL contains all fabrication steps needed to form isolated CMOS elements:[3][4]
- Selecting the type of wafer to be used; Chemical-mechanical planarization (CMP) and cleaning of the wafer.
- Shallow trench isolation (STI) (or LOCOS in early processes with feature size > 0.25 μm);
- Well formation;
- Gate module formation;
- Source and drain module formation.
Finally, the surface is treated to prepare the contacts for the subsequent metallization. This concludes the FEOL process, that is, all devices have been built.[4]
Following these steps, the devices must be connected electrically as per the nets to build the electrical circuit. This is done in the back-end-of-line (BEOL). BEOL is thus the second portion of IC fabrication where the individual devices are connected.[4]
See also
References
- ^ Karen A. Reinhardt and Werner Kern (2008). Handbook of Silicon Wafer Cleaning Technology (2nd ed.). William Andrew. p. 202. ISBN 978-0-8155-1554-8.
- ^ "FEOL (Front End of Line: substrate process, the first half of wafer processing) 1. Isolation | USJC：United Semiconductor Japan Co., Ltd". USJC：United Semiconductor Japan Co., Ltd. | 三重県桑名市の300mm半導体ウェーハ工場を製造拠点にしたファウンドリ専業メーカーです。超低消費電力、不揮発メモリなど先進テクノロジーを世界中のお客様に提供しています。 (in Japanese). 2019-02-22. Retrieved 2022-09-27.
- ^ Ramsundar, Bharath. "A Deep Dive into Chip Manufacturing: Front End of Line (FEOL) Basics". deepforest.substack.com. Retrieved 2022-09-27.
- ^ a b c J. Lienig, J. Scheible (2020). "Chap. 2.9.3: FEOL: Creating Devices". Fundamentals of Layout Design for Electronic Circuits. Springer. pp. 78–82. doi:10.1007/978-3-030-39284-0. ISBN 978-3-030-39284-0. S2CID 215840278.
Further reading
- "CMOS: Circuit Design, Layout, and Simulation" Wiley-IEEE, 2010. ISBN 978-0-470-88132-3. pages 177-178 (Chapter 7.2 CMOS Process Integration); pages 180-199 (7.2.1 Frontend-of-the-line integration)
- "Fundamentals of Layout Design for Electronic Circuits", by Lienig, Scheible, Springer, doi:10.1007/978-3-030-39284-0ISBN 978-3-030-39284-0, 2020. Chapter 2: Technology Know-How: From Silicon to Devices, pages 78-82 (2.9.3 FEOL: Creating Devices)