Process for fabricating capacitor having dielectric layer with perovskite structure and apparatus for fabricating the same

Abstract

A barium strontium titanate is the ferroelectric substance with the perovskite structure available for a capacitor as a dielectric layer, and is crystallized through a high temperature heat treatment, in which the barium strontium titanate is further subjected to a low temperature heat treatment under the crystallizing temperature of the barium strontium titanate for eliminating impurities such as carbon and hydrogen therefrom so that the leakage current is drastically reduced.

What is claimed is:  
     
         1 . A process for fabricating a capacitor, comprising the steps of: 
 a) preparing a semiconductor structure having a semiconductor substrate;    b) forming a first electrode on said semiconductor structure;    c) depositing a ferroelectric complex oxide expressed as ABO 3  on said lower electrode; and    d) completing a capacitor through a high temperature heat treatment for crystallizing said ferroelectric complex oxide, a low temperature heat treatment for eliminating impurities causative of degradation from said ferroelectric complex oxide and forming a second electrode on said ferroelectric complex oxide.    
     
     
         2 . The process as set forth in    claim 1   , in which said high temperature heat treatment is carried out in a temperature range for crystallizing said ferroelectric complex oxide, and said low temperature heat treatment is carried out under said temperature range.  
     
     
         3 . The process as set forth in    claim 1   , in which said ferroelectric complex oxide has a perovskite structure.  
     
     
         4 . The process as set forth in    claim 1   , in which said step d) includes the sub-, steps of 
 d-1) carrying out said high temperature heat treatment in a temperature range for crystallizing said ferroelectric complex oxide,    d-2) depositing a conductive material on the layer of said ferroelectric complex oxide,    d-3) carrying out said low temperature heat treatment under said temperature range, and    d-4) patterning the layer of said conductive layer into said second electrode.    
     
     
         5 . The process as set forth in    claim 1   , in which said deposition of said ferroelectric complex oxide and said high temperature heat treatment are repeated before said low temperature heat treatment.  
     
     
         6 . The process as set forth in    claim 1   , in which said deposition of said ferroelectric complex oxide, said high temperature heat treatment and said low temperature heat treatment are repeated before the formation of said second electrode.  
     
     
         7 . The process as set forth in    claim 1   , in which said step d) includes the sub-steps of 
 d-1) carrying out said low temperature heat treatment under a temperature range for crystallizing said ferroelectric complex oxide,    d-2) carrying out said high temperature heat treatment in said temperature range, and    d-3) forming said second electrode.    
     
     
         8 . The process as set forth in    claim 1   , in which said step d) includes the sub-steps of 
 d-1) carrying out said high temperature heat treatment in a temperature range for crystallizing said ferroelectric complex oxide,    d-2) carrying out said low temperature heat treatment under said temperature range, and    d-3) forming said second electrode.    
     
     
         9 . The process as set forth in    claim 1   , in which said step d) includes the sub-steps of 
 d-1) forming said second electrode,    d-2) carrying out said high temperature heat treatment in a temperature range for crystallizing said ferroelectric complex oxide, and    d-3) carrying out said low temperature heat treatment under said temperature range.    
     
     
         10 . The process as set forth in    claim 1   , in which said low temperature heat treatment is carried out in inert atmosphere containing oxygen at zero to 5 percent.  
     
     
         11 . The process as set forth in    claim 1   , in which said ferroelectric complex oxide is expressed as (Ba, Sr)TiO 3 , and said high temperature heat treatment and said low temperature heat treatment are carried out in a first temperature range between 520 degrees and 900 degrees in centigrade and in a second temperature range between 250 degrees and 500 degrees in centigrade, respectively.  
     
     
         12 . An apparatus for fabricating a capacitor comprising 
 a first chamber for depositing a ferroelectric complex oxide expressed as ABO 3  on a semiconductor structure having a first electrode,    a second chamber for a high temperature heat treatment through which said ferroelectric complex oxide is crystallized,    a third chamber for a low temperature heat treatment through which impurity causative of degradation is eliminated from said ferroelectric complex oxide, and    a transfer system for conveying said semiconductor structure from one of said first to third chambers to another without exposing said semiconductor structure to the atmosphere.    
     
     
         13 . The apparatus as set forth in    claim 12   , further comprising a fourth chamber for depositing a conductive material.  
     
     
         14 . The apparatus as set forth in    claim 13   , in which said first chamber to said fourth chamber are arranged around said transfer system.  
     
     
         15 . The apparatus as set forth in    claim 14   , further comprising a load-lock chamber arranged around said transfer system together with said first chamber to said fourth chamber.