Process for fabricating a semiconductor device having deep trench structures

A process for fabricating a dynamic-random-access-memory device comprising:

• a first stage comprising:
• providing a substrate having a substrate surface;
• and
• forming a first portion of a capacitor trench extending into the substrate in a first direction;
• and
• a second stage performed after the first stage, the second stage comprising:
• selectively depositing, by epitaxial deposition, an upper layer on the substrate surface, such that a second portion of the capacitor trench is formed extending away from the substrate surface in a second direction, wherein the second direction is substantially opposite to the first direction, wherein all surfaces of the trench are continuous within the upper layer, and wherein the upper layer increases the effective depth of the trench.

A process for fabricating a semiconductor device comprising:

• a first stage comprising:
• providing a semiconductor substrate having a principal surface;
• forming a first portion of a wall surface in the semiconductor substrate using a masking pattern;
• covering the first portion of a wall surface with an insulating material that is differently etchable with respect to a material of the masking pattern;
• and
• selectively removing the masking pattern with respect to the insulating layer in an etch step such that no residual portion of the masking pattern remains on the principle surface;
• and
• a second stage performed after the first stage, the second stage comprising:
• depositing, by epitaxial deposition, an upper layer overlying the principal surface while simultaneously forming a second portion of the wall surface in the upper layer, wherein the first portion of the wall surface is continuous with the second portion of the wall surface within the upper layer and wherein the upper layer increases the length of the first and second portions of the wall surface.

A process for fabricating a semiconductor device comprising:

• a first stage comprising:
• providing a semiconductor substrate and etching the semiconductor substrate to form a trench having sidewalls and a bottom surface;
• and
• forming a liner in the trench overlying the sidewalls and the bottom surface;
• and
• a second stage performed after the first stage, the second stage comprising:
• selectively depositing, by epitaxial deposition, an upper layer of a semiconductor material on the semiconductor substrate, wherein the layer of semiconductor material comprises a similar crystalline structure as the semiconductor substrate, wherein the upper layer includes sidewalls continuous with the sidewalls of the trench, and wherein the upper layer increases the effective depth of the trench.