Two-terminal nonlinear element and method for fabricating the same

A two-terminal nonlinear element comprising:

• a lower electrode having a top flat portion;
• an insulating layer formed covering the lower electrode;
• an upper electrode formed to partially overlap the lower electrode with the insulating layer interposed therebetween, wherein the capacitance of the two-terminal nonlinear element is determined by the area of the upper electrode;
• wherein a thickness of the insulating layer is thinner in a portion located on the top flat portion of the lower electrode than in a portion located on a portion of the lower electrode other than the top flat portion, and wherein the top flat portion and the portion other than the top flat portion of the insulating film are made of the same metal oxide produced by anodization.

A method of fabricating a two-terminal nonlinear element, comprising:

• forming a lower electrode on a substrate;
• forming an upper electrode;
• and
• forming an insulating film between the lower electrode and the upper electrode, wherein the insulating film has a first portion having a first thickness and a second portion having a second thickness, wherein the first portion is thicker than the second portion, and wherein the capacitance of the two-terminal nonlinear element is determined by the area of the upper electrode;
• wherein the steps of forming the upper electrode and the insulating film comprise:
• forming a first insulating layer over the lower electrode;
• forming a conductive layer over the first insulating layer;
• patterning the conductive layer to a predetermined shape, wherein the patterned conductive layer forms the upper electrode;
• and
• forming a second insulating layer over a portion of the first insulating layer not covered by the upper electrode, wherein the first and second insulating layers collectively form the first portion of the insulating film having the first thickness and the first insulating layer located beneath the upper electrode forms the second portion of the insulating film having the second thickness.

A method of fabricating a two-terminal nonlinear element, comprising:

• forming a lower electrode on a substrate;
• forming an upper electrode;
• and
• forming an insulating film between the lower electrode and the upper electrode, wherein the insulating film has a first portion having a first thickness and a second portion having a second thickness, wherein the first portion is thicker than the second portion, and wherein the capacitance of the two-terminal nonlinear element is determined by the area of the upper electrode;
• forming a second insulating film over the upper electrode and the insulating film, wherein the second insulating film has at least one portion of the film having uneven surfaces;
• and
• forming a pixel electrode on the second insulating film, wherein the pixel electrode has uneven surfaces which correspond to the second insulating film and wherein the pixel electrode serves as a reflector.

A method for fabricating a two-terminal nonlinear element including a lower electrode, an insulating film formed covering the lower electrode, and an upper electrode formed to face the lower electrode via the insulating film, the method comprising the steps of:

• forming a first conductive film on a substrate and then patterning the first conductive film to form the lower electrode;
• performing a first anodization to form the insulating film on at least a portion of the lower electrode;
• forming a second conductive film on the insulating film;
• forming a photosensitive resin layer having a pattern corresponding to a pattern of the upper electrode on the second conductive film;
• patterning the second conductive film into a predetermined shape using the photosensitive resin layer to form the upper electrode;
• performing a second anodization using the pattern of the photosensitive resin layer remained on the upper electrode, to thicken a portion of the insulating film corresponding to a portion surrounding the upper electrode more than a portion of the insulating film interposed between the upper electrode and the lower electrode;
• and
• removing the photosensitive resin layer.