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Etching is a critically important process module in fabrication, and every wafer undergoes many etching steps before it is complete. For many etch steps, part of the wafer is protected from the etchant by a "masking" material which resists etching. In some cases, the masking material is a photoresist which has been patterned using photolithography.
Wafer fabrication is a procedure composed of many repeated sequential processes to produce complete electrical or photonic circuits on semiconductor wafers in a semiconductor device fabrication process. Examples include production of radio frequency amplifiers, LEDs, optical computer components, and microprocessors for computers. Wafer ...
Removal is any process that removes material from the wafer; examples include etch processes (either wet or dry) and chemical-mechanical planarization (CMP). Patterning is the shaping or altering of deposited materials, and is generally referred to as lithography .
Simplified illustration of the process of fabrication of a CMOS inverter on p-type substrate in semiconductor microfabrication. Each etch step is detailed in the following image. The diagrams are not to scale, as in real devices, the gate, source, and drain contacts are not normally located in the same plane. Detail of an etch step.
Xenon difluoride, bromine trifluoride, chlorine trifluoride and fluorine can be used for gaseous silicon etching. [6] [7] Xenon difluoride is most commonly used to etch silicon in academia and industry, because it has a high selectivity towards other semiconductor materials, allows high process control and is easy to use at room temperature. [8 ...
Dry etching is used in conjunction with photolithographic techniques to attack certain areas of a semiconductor surface in order to form recesses in material.. Applications include contact holes (which are contacts to the underlying semiconductor substrate), via holes (which are holes that are formed to provide an interconnect path between conductive layers in the layered semiconductor device ...
The dry etch is then performed so that structured etching is achieved. After the process, the remaining photoresist has to be removed. This is also done in a special plasma etcher, called an asher. [14] Dry etching allows a reproducible, uniform etching of all materials used in silicon and III-V semiconductor technology. By using inductively ...
To etch through a 0.5 mm silicon wafer, for example, 100–1000 etch/deposit steps are needed. The two-phase process causes the sidewalls to undulate with an amplitude of about 100–500 nm . The cycle time can be adjusted: short cycles yield smoother walls, and long cycles yield a higher etch rate.