Temperature-compensated ferroelectric capacitor device, and its fabrication

Abstract

A temperature-compensated capacitor device has ferroelectric properties and includes a ferroelectric capacitor using a ferroelectric material such as a metal oxide ferroelectric material, a negative-temperature-variable capacitor using a negative-temperature-coefficient-of-capacitance material such as a metal oxide paraelectric material, and an electrical series connection between the negative-temperature-variable capacitor and the ferroelectric capacitor. The temperature-compensated capacitor device may be formed as an integrated layered structure, or as separate capacitors with a discrete electrical connection therebetween.

What is claimed is:  
     
         1 . A temperature-compensated capacitor device having ferroelectric properties and comprising: 
 a ferroelectric capacitor comprising a ferroelectric material;    a negative-temperature-variable capacitor comprising a negative-temperature-coefficient-of-capacitance material; and    an electrical series connection between the negative-temperature-variable capacitor and the ferroelectric capacitor.    
     
     
         2 . The temperature-compensated capacitor device of  claim 1 , wherein the electrical series connection comprises a direct physical contact between the ferroelectric capacitor and the negative-temperature-variable capacitor.  
     
     
         3 . The temperature-compensated capacitor device of  claim 1 , wherein the ferroelectric material comprises a ferroelectric layer, and wherein the negative-temperature-coefficient-of-capacitance material comprises a paraelectric layer in direct, facing contact with the ferroelectric layer.  
     
     
         4 . The temperature-compensated capacitor device of  claim 1 , wherein the electrical series connection comprises a discrete electrical connection extending between the ferroelectric capacitor and the negative-temperature-variable capacitor.  
     
     
         5 . The temperature-compensated capacitor device of  claim 1 , wherein the ferroelectric material is a metal oxide ferroelectric material.  
     
     
         6 . The temperature-compensated capacitor device of  claim 1 , wherein the ferroelectric material is a metal oxide ferroelectric material selected from the group consisting of lead titanate, lead zirconate titanate, lead lanthanum zirconate titanate, barium titanate, strontium bismuth tantalate, strontium bismuth niobate, strontium bismuth tantalate niobate, and bismuth lead titanate.  
     
     
         7 . The temperature-compensated capacitor device of  claim 1 , wherein the ferroelectric material is strontium bismuth tantalate niobate.  
     
     
         8 . The temperature-compensated capacitor device of  claim 1 , wherein the negative-temperature-coefficient-of-capacitance material is a paraelectric material.  
     
     
         9 . The temperature-compensated capacitor device of  claim 1 , wherein the negative-temperature-coefficient-of-capacitance material is a metal oxide negative-temperature-coefficient-of-capacitance material.  
     
     
         10 . The temperature-compensated capacitor device of  claim 1 , wherein the negative-temperature-coefficient-of-capacitance material is a metal oxide negative-temperature-coefficient-of-capacitance material selected from the group consisting of strontium titanate and barium strontium titanate.  
     
     
         11 . The temperature-compensated capacitor device of  claim 1 , wherein the negative-temperature-coefficient-of-capacitance material is barium strontium titanate.  
     
     
         12 . A temperature-compensated capacitor device having ferroelectric properties and comprising: 
 a ferroelectric capacitor comprising 
 a first electrode layer, and  
 a ferroelectric layer of a ferroelectric material in direct physical contact with the first-electrode layer; and  
   a negative-temperature-variable capacitor comprising 
 a negative-temperature-variable layer of a negative-temperature-coefficient-of-capacitance material in direct physical contact with the ferroelectric layer, and  
 a second electrode layer in direct physical contact with the temperature-variable layer.  
   
     
     
         13 . A method for fabricating a temperature compensated capacitor having ferroelectric properties, comprising the steps of: 
 providing a first electrode layer;    depositing a ferroelectric precursor layer of a ferroelectric precursor material on the first electrode layer;    reacting the ferroelectric precursor layer to produce a ferroelectric layer;    depositing a negative-temperature-variable precursor layer of a negative-temperature-coefficient-of-capacitance material on the ferroelectric layer;    reacting the negative-temperature-variable precursor layer to form a paraelectric layer; and    placing a second electrode layer on the paraelectric layer.    
     
     
         14 . The method of  claim 13 , wherein the step of providing the first electrode layer includes the step of 
 depositing the first electrode layer, and    wherein the step of placing a second electrode layer includes the step of    depositing the second electrode layer.    
     
     
         15 . The method of  claim 13 , wherein the step of depositing the ferroelectric precursor layer includes the step of depositing a precursor of a metal oxide ferroelectric material.  
     
     
         16 . The method of  claim 13 , wherein the step of depositing the temperature-variable precursor layer includes the step of 
 depositing a precursor of a metal oxide negative-negative-temperature-coefficient-of-capacitance material.