Method of forming borderless contacts using a removable mandrel

A method of forming a strap coupling a trench capacitor with a diffusion region adjacent the capacitor, the method comprising the steps of:

• (a) providing a substrate having (1) a first surface, (2) a trench extending into the substrate and coupled with the first surface, and (3) a diffusion implant region adjacent the trench that confronts the first surface of the substrate, the diffusion implant region having a selected configuration and a selected impurity concentration, the trench being filled with a semiconductor material;
• (b) forming a mandrel overlying the first surface of the substrate, including portions of the diffusion implant region and the trench;
• (c) forming a first opening in the mandrel so as to expose the semiconductor material filling the trench and the diffusion implant region;
• (d) providing doped semiconductor material in said first opening in the mandrel so as to form a strap that contacts (1) the semiconductor material in the trench, (2) portions of the diffusion implant region confronting the first surface of the substrate and (3) portions of the sidewall of the trench;
• (e) heating the substrate for a time and at a temperature sufficient to cause impurities in the diffusion implant region to diffuse into adjacent regions of the substrate, wherein the configuration and impurity concentration of the diffusion implant region is selected so that after said heating step is completed a diffused region is formed that confronts both the top surface of the substrate contacted by the strap and portions of the sidewall of the trench contacted by the strap;
• and
• (f) removing the mandrel and replacing it with a solid dielectric material.

A method of forming contacts to conductive elements forming part of a semiconductor structure, the structure including a substrate having a first surface and a plurality of regions of material deposited on said first surface and extending up from said first surface so as to terminate substantially at a common plane, the regions of material being separated so that openings exist therebetween, the method comprising the steps of:

• (a) providing a first layer of material (i) on the first surface of the substrate in the openings and (ii) overlying the regions of material;
• (b) removing that portion of said first layer of material positioned above the common plane;
• (c) providing a second layer of material on top of said first layer of material;
• (d) forming at least one first opening extending through said second layer and into said first layer;
• (e) depositing a conductive material in said at least one first opening;
• and
• (f) removing said first and second layers and depositing a solid dielectric material in at least a portion of the space created by removal of said first layer of material.