Low-temperature processing of a ferroelectric strontium bismuth tantalate layer, and fabrication of ferroelectric components using the layer
AssigneeInfineon Technologies AG
InventorsHarald Bachhofer, Thomas Haneder, Oswald Spindler, Rainer Waser
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Abstract
In a method for producing ferroelectric strontium bismuth tantalate having the composition SrxBiyTa2O9 (SBT) or SrxBiy(Ta, Nb)2O9 (SBTN), the element strontium, which is normally present in an amount y=2, is provided in excess in a range from 2.1≦y≦3.0. This makes it possible to carry out the heat treatment step for converting the deposited material into the ferroelectric phase at a temperature T1, which is lower than 700° C. In addition, the strontium content x can be reduced from a nominal value of 1 to 0.7.
Claims13
A method for producing ferroelectric SrxBiyTa2O9 (SBT) or SrxBiy(Ta, Nb)2O9 (SBTN), which comprises:
- depositing SrxBiyTa2O9 (SBT) or SrxBiy(Ta, Nb)2O9 (SBTN) on a substrate, where 0.7≦x≦1 and 2.1≦y≦3.0;
- and
- performing a heat treatment step at a temperature T1 being less than 700° C., until the SrxBiyTa2O9 (SBT) or the SrxBiy(Ta, Nb)2O9 (SBTN) has adopted a ferroelectric phase.
A method for fabricating a ferroelectric storage capacitor, which comprises:
- depositing a first electrode layer on a substrate;
- producing a ferroelectric layer on the first electrode layer by:
- depositing SrxBiyTa2O9 (SBT) or SrxBiy(Ta, Nb)2O9 (SBTN) on the first electrode layer, where 0.7≦x≦1 and 2.1≦y≦3.0, and performing a heat treatment step at a temperature T1 being less than 700° C., until the SrxBiyTa2O9 (SBT) or the SrxBiy(Ta, Nb)2O9 (SBTN) has adopted a ferroelectric phase;
- and
- depositing a second electrode layer on the ferroelectric layer.
A method for producing a semiconductor memory, which comprises:
- forming a switching transistor on a semiconductor substrate, the switching transistor having a source region and a drain region;
- applying an insulation layer to the switching transistor;
- fabricating a ferroelectric storage capacitor on the insulation layer by:
- depositing a first electrode layer on the insulation layer,
- producing a ferroelectric layer on the first electrode layer by:
- depositing SrxBiyTa2O9 (SBT) or SrxBiy(Ta, Nb)2O9 (SBTN) on the first electrode layer, where 0.7≦x≦1 and 2.1≦y≦3.0, and performing a heat treatment step at a temperature T1 being less than 700° C., until the SrxBiyTa2O9 (SBT) or the SrxBiy(Ta, Nb)2O9 (SBTN) has adopted a ferroelectric phase, and
- depositing a second electrode layer on the ferroelectric layer;
- and
- performing the step of fabricating the ferroelectric storage capacitor on the insulation layer such that the first electrode layer or the second electrode layer is connected to the source region of the switching transistor or the drain region of the switching transistor.
A method for fabricating a semiconductor transistor, which comprises:
- forming a source region in a surface of a semiconductor substrate on one side of a channel region and forming a drain region in the surface of the semiconductor substrate on another side of the channel region;
- producing a ferroelectric layer on the surface of the semiconductor substrate above the channel region by:
- depositing SrxBiyTa2O9 (SBT) or SrxBiy(Ta, Nb)2O9 (SBTN) on the surface of the semiconductor substrate, where 0.7≦x≦1 and 2.1≦y≦3.0, and performing a heat treatment step at a temperature T1 being less than 700° C., until the SrxBiyTa2O9 (SBT) or the SrxBiy(Ta, Nb)2O9 (SBTN) has adopted a ferroelectric phase;
- and
- applying a gate electrode layer to the ferroelectric layer.
Dependencies are inferred from the claim text.