Patent ID: 6153898
Filing Date: 2000-11-28
Classification: H01L

Abstract:
A ferroelectric capacitor comprising a ferroelectric layer to which a pair of electrodes are connected wherein:the ferroelectric layer includes an oxide of a layered crystal structure consisting of bismuth (Bi), oxygen, at least one first element selected from the group consisting of strontium (Sr), calcium (Ca) and barium (Ba), and at least one second element selected from the group consisting of tantalum (Ta) and niobium (Nb) with a formula of the oxide being represented by Bi.sub.x (Sr, Ca, Ba).sub.y (Ta, Nb).sub.2 O.sub.9.+-.d, wherein 1.70.ltoreq.x.ltoreq.2.50, 0.60.ltoreq.y.ltoreq.1.20 and 0.ltoreq.d.ltoreq.1.00 and the first element of the ferroelectric layer having a variation of proportions in one direction so that the proportion changes from one side of the ferroelectric layer to the other side.