Method of forming a groove-like area in a semiconductor device

A method for manufacturing a semiconductor device having one active area and another active area, and a further active area formed on an element substrate that are electrically isolated from each other, comprising:

• forming a groove-like area at said element substrate by performing a treatment under conditions wherein an etching rate on a first surface is essentially equal to an etching rate on a second surface in an area between said one active area, said another active area and said further active area;
• etching at said groove-like area under conditions wherein said etching rate at said first surface is essentially double or more than double said etching rate on said second surface, and implemented within a hydrogen gas atmosphere containing hydrogen chloride gas at a temperature of 800 degrees centigrade or lower;
• and
• etching a bottom surface of said groove-like area through anisotropic etching.

A method of forming a device isolation area in a semiconductor device, comprising:

• etching a substrate to form a groove-like area in the substrate, under conditions whereby an etching rate of sidewalls of the groove-like area is substantially equal to an etching rate of a bottom surface of the groove-like area;
• etching the groove-like area to further define the groove-like area, under conditions whereby an etching rate of the bottom surface of the groove-like area is essentially double or more an etching rate of the sidewalls of the groove-like area, said etching the groove-like area being performed after completion of said etching a substrate;
• and
• etching the further defined groove-like area to complete formation of the device isolation area, under conditions whereby the further defined groove-like area is anisotropically etched.

A method of forming a device isolation area in a semiconductor device, comprising:

• etching a substrate to form a groove-like area in the substrate, under conditions whereby an etching rate of sidewalls of the groove-like area is substantially equal to an etching rate of a bottom surface of the groove-like area;
• etching the groove-like area to further define the groove-like area, under conditions whereby an etching rate of the bottom surface of the groove-like area is essentially double or more an etching rate of the sidewalls of the groove-like area, said etching the groove-like area being performed after completion of said etching a substrate;
• and
• etching the further defined groove-like area to complete formation of the device isolation area, under conditions whereby the further defined groove-like area is anisotropically etched,
• said etching a substrate is performed in a hydrogen gas atmosphere containing hydrogen chloride gas at a temperature of 900 degrees centigrade or higher, and said etching the groove-like area is performed in a hydrogen gas atmosphere containing hydrogen chloride gas at a temperature of 850 degrees centigrade or lower.