Semiconductor device with a superparaelectric gate insulator
A semiconductor device includes a channel region 18 of semiconductor, a conductive gate electrode 12 adjacent to the channel region 18 and a gate dielectric 10 between the conductive gate electrode 12 and the channel region 18 . The gate dielectric 10 is formed of a material that is a ferroelectric in bulk but in a superparaelectric state. The gate dielectric may be for instance of formula AXO 3 , where A is a group I or II element, and X is titanium, niobium, zirconium and/or hafnium. Such a gate dielectric 10 may be formed for example by low temperature deposition of the gate dielectric 10 or by using dopants of metal oxides to prevent domain growth, or both.
1. A semiconductor device, comprising:
a channel region of a semiconductor;
a conductive gate electrode adjacent to the channel region; and
a gate dielectric between the conductive gate electrode and the channel region, the gate dielectric being a superparaelectric gate dielectric, formed of a material that is a ferroelectric in bulk, and the gate dielectric including a dopant for hindering domain growth, the dopant not forming a solid solution in the gate dielectric material.
2. A semiconductor device according to claim 1 wherein the dopant is an oxide of Nb, La, Zr, Pb, Sr, Mn, W or a rare earth element.
3. A method of making a semiconductor device, comprising:
forming a channel region of a semiconductor;
depositing a gate dielectric;
depositing a gate conductor sandwiching the gate dielectric between the channel region and the gate conductor;
forming a dopant in the gate dielectric to hinder domain growth; and
wherein in the step of depositing the gate dielectric the gate dielectric is formed as a superparaelectric gate dielectric of a material that is a ferroelectric in bulk.
4. A method according to claim 3 wherein the dopant is an oxide not forming a solid solution with the material of the gate dielectric.
5. A method according to claim 4 wherein the dopant is an oxide of Si, Ca, Al, Nb, La, Zr, Pb, Sr, Mn, W or a rare earth element, or combinations of these oxides.
6. A method of making a semiconductor device, the method comprising:
depositing a superparaelectric gate dielectric material using a material that is a ferroelectric in bulk, while limiting the temperature of the gate dielectric material to less than 300° C. to mitigate the formation of ferroelectric domains in the gate dielectric material;
doping the gate dielectric material with an oxide dopant that does not form a solid solution with the material of the gate dielectric, to mitigate the formation of ferroelectric domains in the gate dielectric material; and
depositing a gate conductor sandwiching the gate dielectric between the channel region and the gate conductor.