Method of forming isolated device regions by selective successive etching of composite masking layers and semiconductor material prior to ion implantation

A method for forming a semiconductor structure comprising the steps of:

• (a) forming a mask comprising upper and lower layers of different material over a surface of a semiconductor with a first window in such lower layer exposing a portion of the surface of the semiconductor and a smaller, second window in the upper layer having extended peripheral portions masking peripheral portions of the exposed surface portion of the semiconductor, the length of each extended peripheral portion of the upper layer being greater than the thickness of the lower layer;
• (b) bringing an etchant into contact with the exposed surface portion of the semiconductor forming a depression in such semiconductor with side wall portions masked by the extended peripheral portions of the second window;
• and
• (c) ion implanting particles into a region of the semiconductor below the depression exposed by the second window and unmasked by the peripheral portions of the second window.

A method for forming a semiconductor structure comprising the steps of:

• (a) forming a first layer of a first material over a surface of a semiconductor;
• (b) forming a second layer of a second, different material over the first layer;
• (c) forming a first window in a portion of the second layer and exposing portions of the first layer;
• (d) bringing a chemical etchant into contact with the exposed edge portions of the first layer to selectively etch the portions of the first layer providing a second window in the first layer larger than the first window, peripheral portions of the second window extending over the first window an amount greater than the thickness of the first layer and wherein the first window exposes a portion of the surface of the semiconductor and with edge portions of the second window overhanging peripheral portions of the exposed portion of the semiconductor;
• (e) bringing an etchant into contact with the portion of the semiconductor exposed by the second window forming a depression in the semiconductor with side wall portions and a bottom portion, the extended peripheral portions of the first window overhanging such side wall portions to mask such side wall portions;
• (f) ion implanting particles into a region disposed at the bottom portion of the depression with the extended peripheral portions of the first window masking the side wall portions of such depression preventing ion implantation of such particles into the side wall portions of such depression.

A method for forming a semiconductor structure comprising the step of:

• (a) providing a substrate;
• (b) forming an epitaxial layer of semiconductor material on the substrate;
• (c) forming a mask comprising upper and lower layers of different materials over a surface of the epitaxial layer with a first window in the lower layer and a second, smaller window in the upper layer, edge portions of the second window overhanging edge portions of the first window a length greater than the thickness of the lower layer;
• (d) forming a depression in the portion of the epitaxial layer disposed beneath the first window with side wall portions masked by the overhanging edge portions of the second window;
• and
• (e) ion implanting particles into a region of the epitaxial layer disposed beneath the depression exposed by the second window and unmasked by the edge portions of the second window.

A method for forming a semiconductor structure comprising the steps of:

• (a) providing a substrate;
• (b) forming an epitaxial layer of semiconductor material on the substrate;
• (c) forming a mask comprising upper and lower layers of different material over a surface of the epitaxial layer with a first window in such lower layer exposing a portion of the surface of the semiconductor and a smaller, second window in the upper layer having extended peripheral portions masking peripheral portions of the exposed surface portion of the semiconductor, the length of each extended peripheral portion of the upper layer being greater than the thickness of the lower layer;
• (d) bringing an etchant into contact with the exposed surface portion of the epitaxial layer forming a depression in such semiconductor with side wall portions masked by the extended peripheral portions of the second window;
• and
• (e) ion implanting particles into a region of the epitaxial layer below the depression exposed by the second window and unmasked by the peripheral portions of the second window.

A method for forming a semiconductor structure comprising the steps of:

• (a) providing a substrate;
• (b) forming an epitaxial layer of semiconductor material on the substrate;
• (c) forming a first layer of a first material over a surface of a the epitaxial layer;
• (d) forming a second layer of a second, different material over the first layer;
• (e) forming a first window in a portion of the second layer and exposing portions of the first layer;
• (f) bringing a chemical etchant into contact with the exposed portions of the first layer to selectively etch the portions of the first layer providing a first window in the first layer larger than the second window, peripheral portions of the second window extending over the first window an amount greater than the thickness of the first layer and wherein the second window exposes a portion of the surface of the epitaxial layer and with edge portions of the first window overhanging peripheral portions of the exposed portion of the epitaxial layer;
• (g) bringing an etchant into contact with the portion of the epitaxial layer exposed by the second window forming a depression in the epitaxial layer with side wall portions and a bottom portion, the extended peripheral portions of the first window overhanging such side wall portions to mask such side wall portions;
• (h) ion implanting particles into a region disposed at the bottom portion of the depression formed in the epitaxial layer with the extended peripheral portions of the first window masking the side wall portions of such depression preventing ion implantation of such particles into the side wall portions of such depression.