CMOS FABRICATION By: Joaquin Gabriels November 24th, 2008 Outline ▣ ▣ ▣ ▣ ▣ Overview of CMOS CMOS Fabrication Process Overview CMOS Fabrication Process Problems with Current CMOS Fabrication Future Changes in CMOS Fabrication What is CMOS? ▣ ▣ http://en.wikipedia.org/wiki/CMOS Complementary metal–oxide–semiconductor (CMOS) Has many different uses: ◼ ◼ ◼ ◼ ◼ Integrated Circuits Data converters Integrated transceivers Image sensors Logic circuits What is CMOS? NAND Circuit CMOS Fabrication Process Overview http://lsmwww.epfl.ch/Education/former/20022003/VLSIDesign/ch02/ch02.html CMOS Fabrication Process 1. 2. 3. 4. Create a pattern. Oxidize small layer, about 1µm thick. Place photoresist on top of SiO2 Place mask(pattern) above photoresist and expose it to UV light. CMOS Fabrication Process CMOS Fabrication Process CMOS Fabrication Process 1. 2. Etch away SiO2 using HF acid or plasma. Remove remaining photoresist with acids. CMOS Fabrication Process ▣ To create a n well: ◼ Diffusion ◼ Heat wafer in Arsenic gas chamber until diffusion occurs. ◼ Ion Implantation ◼ Arsenic or phosphorous are implanted in window. CMOS Fabrication Process CMOS Fabrication Process ▣ ▣ A thin layer of oxide is deposited. A thin layer of polysilicon is deposited using Chemical Vapor Deposition (CVD) . CMOS Fabrication Process http://en.wikipedia.org/wiki/Chemical_vapor_deposition CMOS Fabrication Process ▣ ▣ Remove oxide layer using acid. Dope open area using Ion implantation or diffusion. CMOS Fabrication Process CMOS Fabrication Process Problems with Current CMOS Fabrication ▣ ▣ ▣ ▣ Optical lithography is limited by the light frequency. Material limitations Yield limitations Space limitations Future Changes in CMOS Fabrication ▣ ▣ Material changes like using high-k materials. Design changes ◼ ◼ ◼ SOI(Silicon On Insulator) Double Gate (Finfet) Twin-Tub Process Future Changes in CMOS Fabrication Future Changes in CMOS Fabrication Future Changes in CMOS Fabrication Future Changes in CMOS Fabrication Future Changes in CMOS Fabrication http://www.fujitsu.com/downloads/MAG/vol39-1/paper02.pdf References ▣ ▣ ▣ ▣ ▣ ▣ ▣ ▣ ▣ ▣ CMOS Digital Integrated Circuit Design - Analysis and Design by S.M. Kang and Y. Leblebici http://www.fujitsu.com/downloads/MAG/vol39-1/paper02.pdf “Introduction to VLSI Circuits and Systems,” John Wiley and Sons, 2002 http://lsmwww.epfl.ch/Education/former/20022003/VLSIDesign/ch02/ch02.html http://en.wikipedia.org/wiki/Chemical_vapor_deposition users.ece.utexas.edu/~adnan/vlsi-05/lec0Fab.ppt http://en.wikipedia.org/wiki/CMOS www.usna.edu/EE/ee452/LectureNotes/02_CMOS_Process_Steps/08_Simple_CMOS_Fab.ppt http://en.wikipedia.org/wiki/Silicon_on_insulator access.ee.ntu.edu.tw/course/VLSI_design_90second/data/Chapter%203%20Part 2%2003-20-2002.doc
