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In the semiconductor industry, the term high-κ dielectric refers to a material with a high dielectric constant (κ, kappa), as compared to silicon dioxide.High-κ dielectrics are used in semiconductor manufacturing processes where they are usually used to replace a silicon dioxide gate dielectric or another dielectric layer of a device.
A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field. Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field ...
Dielectric materials can be solids, liquids, or gases. (A high vacuum can also be a useful, [23] nearly lossless dielectric even though its relative dielectric constant is only unity.) Solid dielectrics are perhaps the most commonly used dielectrics in electrical engineering, and many solids are very good insulators.
Barium titanate is a dielectric ceramic used in capacitors, with dielectric constant values as high as 7,000. Over a narrow temperature range, values as high as 15,000 are possible; most common ceramic and polymer materials are less than 10, while others, such as titanium dioxide (TiO 2), have values between 20 and 70. [12]
The advantage for transistors is its high dielectric constant: the dielectric constant of HfO 2 is 4–6 times higher than that of SiO 2. [9] The dielectric constant and other properties depend on the deposition method, composition and microstructure of the material.
A perfect conductor has infinite conductivity, σ = ∞, while a perfect dielectric is a material that has no conductivity at all, σ = 0; this latter case, of real-valued permittivity (or complex-valued permittivity with zero imaginary component) is also associated with the name lossless media. [18]
Using the Clausius-Mossotti relation, the calculated intrinsic dielectric constant should be 49. [3] However, CCTO exhibits a dielectric constant upwards of 10,200 at 1 MHz, with a low loss tangent until approximately 300 °C. [4] [5] In addition, the relative dielectric constant increases with decreasing frequency (in the range of 1 MHz to 1 kHz).
[12] [13] [14] In general the more amorphous the material the greater its observed band gap. These observed values are significantly higher than those predicted by computational chemistry (2.3 - 3.8 eV). [15] [16] [17] Its dielectric constant is typically about 25 [18] although values of over 50 have been reported. [19]