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1、Introduction to CMOS Device and Fabrication TechnologiesQ&A Engineer Wu Caifeng DaTang Microelectronic Technology Co., LTD Tel:010-62302525 - DMT Q&A training Organization? CMOS Device Principle? VLSI Fabrication Technologies- DMT Q&A training Simplified View of MOSFET- DMT Q&A training CMOS Device
2、Principle- DMT Q&A training BiCMOS TechnologyBipolar transistors have superior current driving characteristics compared to MOS transistors. The Bipolar-CMOS (BiCMOS) process has additional layers for the inclusion of bipolar transistors alongside regular CMOS structures.- DMT Q&A training Organizati
3、on? CMOS Device Principle? VLSI Fabrication Technologies- DMT Q&A training Overview of Processing TechnologiesAlthough a number of processing technologies are available, few are actively used. The majority of the production is done with traditional CMOS, other processes are limited to areas where CM
4、OS is not very suitable (like high speed RF applications):? CMOS (90%) ? BiCMOS (5%) ? Bipolar (2%) ? GaAs (2%) ? SOI (1%)Typical breakdown of the worldwide semiconductor fabrication- DMT Q&A training ConductorsConductors are used in IC design for electrical connectivity. The following are good cond
5、ucting elements:? Silver ? Gold ? Copper ? Aluminum ? Platinum ? Bismuth ? Tungsten- DMT Q&A training Single Crystal Silicon The silicon crystal (in some cases also containing doping) is manufactured (pulled) as a cylinder with a diameter of 8-12 inches.This cylinder is carefully sawed into thin dis
6、ks (wafers). The wafers are later polished and marked for crystal orientation.- DMT Q&A training LithographyAn IC consists of several layers of material that are manufactured in successive steps. Lithography is used to selectively process the layers, where the 2-D mask geometry is copied on the surf
7、ace.- DMT Q&A training LithographyThe surface of the wafer is coated with a photosensitive material, the photoresist. The mask pattern is developed on the photoresist, with UV light exposure.Depending on the type of the photoresist (negative or positive), the exposed or unexposed parts of the photor
8、esist change their property and become resistant to certain types of solvents.Subsequent processing steps remove the undeveloped photoresist from the wafer. The developed pattern (usually) protects the underlying layer from an etching process. The photoresist is removed after patterning on the lower
9、 layer is completed.- DMT Q&A training Lithography- DMT Q&A training Lithography- DMT Q&A training EtchingEtching is a common process to pattern material on the surface. Once the desired shape is patterned with photoresist, the unprotected areas are etched away, using wet or dry etch techniques. - D
10、MT Q&A training Oxide Growth / Oxide DepositionOxidation of the silicon surface creates a SiO2 layer that acts as an insulator. Oxide layers are also used to isolate metal interconnections.An annealing step is required to restore the crystal structure after thermal oxidation.- DMT Q&A training Ion I
11、mplantationIon implantation is used to add doping materials to change the electrical characteristics of silicon locally. The dopant ions penetrate the surface, with a penetration depth that is proportional to their kinetic energy. - DMT Q&A training Thin Film DepositionThere are two main methods for
12、 thin film deposition:? PVD Physical Vapor Deposition ? CVD Chemical Vapor DepositionWhile some of the structures can be grown on silicon substrate, most of the other materials (especially metal and oxide) need to be deposited on the surface. In most cases, the material that is deposited on the whol
13、e surface will be patterned and selectively etched.- DMT Q&A training Well CreationThe first step of processing is to create a deeply implanted n-well.This is done either by diffusion or ion implantation.- DMT Q&A training Definition of Active AreasThe next step is to define the active areas where the transistors will later be created. A thermal oxide is grown uniformly on the surface. Then the active areas are covered by nitride. A second thermal oxidation process grows thick silicon dioxide outside the active areas.-
