Method of forming element isolating region in a semiconductor device

A method of forming an element isolating region in a semiconductor device, comprising the steps of:

• forming a mask consisting of an insulating film having a first opening on an element isolation forming region, on a main surface of a semiconductor substrate;
• introducing an impurity having same conductivity type as said semiconductor substrate to said semiconductor substrate from above said mask by ion implantation, and forming an ion-implanted impurity layer having a prescribed depth at the main surface of said semiconductor substrate on which the first opening of said mask is positioned;
• heat treating said semiconductor substrate in which said ion-implanted impurity layer is formed, diffusing ions introduced to said ion-implanted impurity layer to form an impurity layer;
• forming a second opening by enlarging said first opening of said mask;
• forming a trench by etching said impurity layer on which said second opening of said mask is positioned, by using said mask, so that said impurity layer left in contact with side and bottom surfaces of the trench serves as a channel stopper;
• and
• filling said trench with an insulating material.

A method of forming an element isolation region in a semiconductor substrate, which method comprises:

• depositing a layer of insulating material on the substrate;
• forming a resist mask on the insulating layer, wherein the resist mask contains an opening therein exposing the insulating layer;
• etching the insulating layer to form an opening having a width W, thereby exposing the substrate;
• removing the resist mask;
• introducing an impurity of the same conductivity as the substrate, after removing the resist mask, from above the insulating layer through the opening having a width W in a direction perpendicular to the substrate by ion implantation to form an ion implanted impurity layer in the substrate;
• heat treating the substrate to diffuse the implanted impurity ions, thereby increasing the size of the ion implanted impurity layer to form a diffused impurity region;
• forming a trench by etching the semiconductor substrate through the opening in the insulating layer having a width of W to remove substantially all of the ion implanted impurity layer to form a trench having a width of about W, substantially leaving the diffused impurity portion on side and bottom surfaces of the trench to serve as a channel stopper layer;
• and
• filling the trench with an insulating material.

A method of forming an element isolation region in a semiconductor substrate, which method comprises:

• depositing a layer of an insulating material on the substrate;
• forming a resist mask on the insulating layer, wherein the resist mask contains an opening therein exposing the insulating layer;
• etching the insulating layer to form an opening defined by the insulating material, thereby exposing the substrate;
• removing the resist mask;
• introducing an impurity of the same conductivity as the substrate, after removing the resist mask, from above the insulating layer through the opening defined by the insulating material in a direction perpendicular to the substrate by ion implantation to form an ion implanted impurity layer in the substrate;
• heat treating the substrate to diffuse the implanted impurity ions, thereby increasing the size of the ion implanted impurity layer to form a diffused impurity region;
• forming a trench by etching the semiconductor substrate through the opening defined by the insulating material to remove substantially all of the ion implanted impurity layer substantially leaving the diffused impurity portion on side and bottom surfaces of the trench to serve as a channel stopper layer;
• and
• filling the trench with an insulating material.