The Role of Electronic Chemicals in Semiconductors
Semiconductors play a crucial role in the functioning of modern electronic devices such as computers, smartphones, televisions and more. These components require certain chemicals during the manufacturing process to achieve the desired electronic properties. Some of the most common electronic chemicals used in semiconductor manufacturing include:
Silicon - Elemental silicon is the base material for most semiconductors due to its uniquely tunable Electronic Chemicals properties. Highly purified silicon crystals are grown and doped with trace amounts of other elements to control conductivity. Precise quantities of trichlorosilane, a silicon source chemical, are used during the crystal growth and doping stages.
Dopants - To alter the conductivity of silicon for either n-type or p-type semiconducting behavior, controlled amounts of Group III/V (boron, aluminum, gallium) or Group V (phosphorus, arsenic) dopant chemicals are introduced. For n-type, phosphine or arsine gases provide the dopants, while diborane or boron trifluoride serve as p-type dopants. Proper doping levels are critical for semiconductor performance.
Etchants - Various plasma etching chemicals like chlorine, fluorine and their compounds are employed to precisely sculpt microscopic circuits and components on silicon wafers. Isotropic and anisotropic etches allow for bulk and selective removal of silicon. Precise etching is key for modern semiconductor miniaturization.
Native Oxide Removers - Prior to deposition of additional layers, the thin native silicon oxide layer must be removed to enable strong interfacial bonding. Chemicals like hydrofluoric acid are commonly employed as native oxide removers to prepare the surface for subsequent processes.
Purification of Electronic Chemicals
For semiconductor applications, electronic chemicals must meet extremely stringent purity specifications. Even trace impurities can compromise semiconductor performance and yield. Thus, sophisticated purification techniques are required:
Distillation - Multiple precisely controlled distillations, often under vacuum or inert gas atmospheres, are used to separate chemicals based on their boiling points. This removes higher-boiling unintended byproducts.
Zone Refining - A zone refining process involves slowly drawing an ingot of the material to be purified through a heating zone. Impurities concentrate in the solid/liquid interface and are trapped, elevating purity.
Sub-boiling Distillation - At temperatures below the normal boiling point using vacuum distillation or constant-boiling mixtures, trace volatile impurities can be more effectively separated from the primary material.
Combustion Synthesis - Igniting a precursor compound in a controlled oxygen environment produces an end product with the carbon, hydrogen and nitrogen impurities oxidized and removed. Additional distillations further elevate purity.
Getter Purification - Exposing vapors of the it to reactive "getter" materials like ZrAl selectively removes reactive gases down to sub-parts-per-billion levels. Critical for delicate thin film depositions.
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