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SiO2 applied in integrated circuits
Sep 07, 2018

                                                                SiO2 applied in integrated circuits

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Although silicon is a semiconductor material, SiO2 is a good insulating material, and it has extremely stable chemical properties, these excellent characteristics make it has a very wide range of applications in IC manufacturing. It can be said that not only is "silicon" leading us into the Silicon Age, but also the main uses of SiO2. SiO2 in IC manufacturing are reflected in the following aspects:

1. masking impurities

      Silica acts as a masking agent for the diffusion of impurities. In IC manufacturing, diffusion of boron,                       phosphorus and arsenic in silica films is much slower than that in silicon. Therefore, the most commonly 

    used method to fabricate various regions of semiconductor devices (such as the source and drain regions of          transistors) is to first produce a layer of SiO2 oxide film on the surface of silicon wafer, after photolithography          and development, then etch the oxide film on the surface of the doped region, thus forming a doping window, 

     and finally selectively impurity through the window. Chi is injected into the corresponding area.

2. gate oxide

In the manufacturing process of MOS/CMOS integrated circuits, SiO2 is usually used as the insulating gate dielectric of MOS transistors, i.e. gate oxide layer.

3. dielectric isolation

The isolation methods in IC fabrication include PN junction isolation and dielectric isolation, in which the dielectric isolation is usually chosen by SiO2 oxide film. For example, the field oxygen in the CMOS process (used to isolate PMOS and NMOS transistors) is a SiO2 film used to isolate the active regions of PMOS and NMOS transistors.

4. insulating medium

Silicon dioxide is a good insulator, so for multi-layer metal wiring structure, it is used as an insulating medium between the upper and lower layers of metal, can prevent short circuit between metals.