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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 .
The standard example is etching of silicon by alternating reaction with chlorine and etching with argon ions. This is a better-controlled process than reactive ion etching , though the issue with commercial use of it has been throughput; sophisticated gas handling is required, and removal rates of one atomic layer per second are around the ...
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.
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 ...
In particular, it was observed that noble metal particles sink down into the material when the sample is immersed in an etching solution containing an oxidizing agent and hydrofluoric acid (see image in the introduction). [3] This method is now commonly called the metal assisted chemical etching of silicon.
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.