New materials show potential in substituting silicon dioxide gate dielectric where continued thinning makes it increasingly difficult to control current leakage. New class materials known as "high-k" will replace silicon technology that will provide support over several generations!
"High-k" stands for high dielectric constant, a measure of how much charge a material can hold (Intel, 2007). Different materials have different abilities to hold charge (sponge concept) and that directly relates to transistor performance. "High-k" materials, have a dielectric constant above 3.9 (the "k" of SiO2) and that means it is able to hold more charges than the silicon element. It is important to know that higher "k" increases transistor capacitance so that the transistor can switch properly between "on" and "off"without leaking any charges.
It is already known that the high-k material to be implemented in future processors will be hafnium based.
Because this high-k gate dielectric is not compatible with today's silicon gate electrode, a new METAL gate is introduced. Incompatibility between the gate dielectric and gate electrode causes undesirable effects and lower transistor performance. (Refer to part 1 if you need to see the connection between the gate di-electric and gate electrode).
The combination of new materials (metal gates and high-k gate dielectric) leads to transistors with very low current leakage and that brings forward energy-efficient and high performance processors.
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