Glossary - D's

Decibel (dB) an expression of the ratio of two values of power or voltage in logarithmic terms.

Density the mass-per-unit volume of a material.

Deposition (sc) process in which layers are formed as the result of a chemical reaction in which the desired layer material is formed and coats the wafer surface.

Desiccant (r) compounding material used to irreversibly absorb moisture present (in a rubber mix) particularly for the purpose of minimizing risk of porosity during vulcanization.

Developer (sc) chemical used to remove areas defined in the masking and exposure step of wafer fabrication.

Die swell (r) difference between the dimensions of the cross section of an extrudate and the corresponding dimensions of the die orifice by which the extrudate is formed.

Dielectric (sc) a material that conducts no current when it has voltage across it.

Diene polymer (r) a polymer formed from one or more monomer species, at least one of which is a diolefin.

Diffusion the spontaneous mixing of one substance with another when in contact with, or separated by, a permeable membrane or microporous barrier.

Diffusion (sc) a process used in semiconductor fabrication which introduces minute amounts of impurities (dopants) into a substrate material and permits the impurity to spread into the substrate. The process is very dependent on temperature and time.

Dipole a molecule with positive and negative charge centers.

Dispersing agent (latex) (r) a surface-active substance used to facilitate the suspension of solid compounding materials in a liquid medium and to stabilize the dispersion thereby produced.

Dispersion (the act of) (r) application of shearing forces to distribute one or more compounding materials uniformly throughout the mass of a continuum material.

Dopant (sc) an element that alters the conductivity of a semiconductor by contributing either a hole or electron to the conduction process. For silicon, the dopants are found in Groups III and V of the periodic table.

Doping (sc) the introduction of impurity atoms (dopants) into the crystal lattice of a semiconductor.

Dry etching (sc) a process resulting in the selective removal of material, achieved by the use of gas or plasma.

Dry-ox (sc) the growth of silicon dioxide using oxygen and hydrogen, which forms water vapor at process temperatures, rather than using water vapor directly.

Dumbbell specimen (r) a flat specimen having a narrow, straight central portion of essentially uniform cross section.

Durometer (r) an instrument for measuring the indentation hardness of rubber.

Dynamic random access memory (DRAM) (sc) memory device for the storage of digital information. The information is stored in a “volatile” state.

Dynamic seal (r) a seal designed to prevent leakage between surfaces which move relative to each other.

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