Semiconductor structures having t-shaped electrodes

Abstract

A semiconductor structure having a T-shaped electrode. The electrode has a top portion and a narrower stem portion extending from the top portion to a surface of a substrate. A solid dielectric layer has side portions juxtaposed and abutting sidewalls of a lower portion of the stem of electrode. A bottom surface of the top portion is spaced from an upper surface portion by a non-solid, dielectric, such as air.

What is claimed is: 
     
         1 . A semiconductor structure comprising:
 a T-shaped electrode; and   a solid dielectric layer having side portions abutting sidewalls of a lower portion of the stern of electrode, the bottom surface of the top of the electrode being spaced from the solid dielectric by a non-solid dielectric.   
     
     
         2 . A semiconductor structure, comprising:
 a T-shaped electrode having a top portion and a narrower stern portion extending from the top portion to a surface of a substrate;   a solid dielectric layer having side portions juxtaposed and abutting sidewalls of a lower portion of the stem of electrode, a bottom surface of the top portion being spaced from is an upper surface portion by a non-solid dielectric.   
     
     
         3 . The semiconductor structure recited in  claim 2  wherein the non-solid dielectric is air. 
     
     
         4 . A method for forming a T-shaped electrode for a semiconductors structure, comprising:
 photolithographically forming a first window through a stack of at least a pair of dielectric layers to expose an underlying surface portion of a substrate, an upper one of the layers having an etch rate higher than an etch rate of a lower one of the layers to a predetermined etchant;   forming a photoresist layer over the dielectric layers and through window onto the exposed surface portion of the substrate;   forming a second window, the second window being in a portion of the photoresist layer in registry with the first window to again expose the surface portion of the substrate with another portion of the photoresist layer being on portions of the upper one of the dielectric layers adjacent to the second window;   depositing a metal through the first window and through the second window onto the exposed portion surface portion of the substrate, portions of the metal being deposited on the said another portion of the photoresist layer, a bottom portion of the metal being juxtaposed sidewalls of the lower one of the dielectric layers forming a portion of the second window;   lifting off the photoresist layer from the upper one of the dielectric layers along with the portions of the metal deposited on the said another portion of the photoresist layer;   exposing the upper one of the dielectric layers to a first etchant to selectively remove the upper one of the dielectric layers, the etchant stopping at the lower one of the dielectric layers.   
     
     
         5 . The method recited in  claim 4  including:
 exposing a middle one of the dielectric layers to an etchant different from the first-mentioned etchant to remove the middle one of the dielectric layers, the different etchant stopping at, or in, the lower one of three dielectric layers. 
 
     
     
         6 . A method for forming a T-shaped electrode for a semiconductors structure, comprising:
 photolithographically forming a first window through a stack of three dielectric layers to expose an underlying surface portion of a substrate, a middle one of the three layers having an etch rate higher than an etch rate of an upper one of the three layers to a predetermined etchant;   forming a photoresist layer on an upper one of the dielectric layers and onto the exposed surface portion of the substrate;   forming a second window, the second window being in a portion of the photoresist layer in registry with the first window to again expose the surface portion of the substrate with another portion of the photoresist layer being on portions of the upper one of the dielectric layer adjacent to the second window;   depositing a metal through the first window and through the second window onto the exposed portion surface portion of the substrate, portions of the metal being deposited on the said another portion of the photoresist layer, a bottom portion of the metal being juxtaposed sidewalls of the lower dielectric layer forming a portion of the second window;   lifting of the photoresist layer from the upper one of the three dielectric layers along with the with the portions of the metal deposited on the said another portion of the photoresist layer;   exposing the upper one of the dielectric layers to a first etchant to selectively remove the upper one of the three dielectric layers, the etchant stopping at, or in the middle one of the three dielectric layers.   
     
     
         7 . The method recited in  claim 6  including:
 exposing the middle one of the three dielectric layers to an etchant different from the first-mentioned etchant to remove the middle one of the dielectric layers, the different etchant stopping at, or in, the lower one of three dielectric layers.