Quantum device and fabrication method thereof

A quantum wire structure, comprising:

• a silicon substrate of a conduction type, comprising a protrusion forming a ridge having a triangular cross section;
• an impurity layer formed on the sides of the protrusion, the impurity layer having an opposite conduction type than the conduction type of the silicon substrate;
• and
• a fine conduction line formed in the top portion of the protrusion and in contact with the impurity layer;
• wherein the fine conduction line is electrically isolated from the silicon substrate.

A quantum wire structure, comprising:

• a silicon substrate of a conduction type, comprising a protrusion forming a ridge having a triangular cross section;
• an insulator layer formed on the protrusion, the insulation layer covering the top of the protrusion;
• and
• a gate electrode layer formed on the insulator layer;
• whereby an electric voltage is applied to the gate electrode to form a fine conduction line in the top portion of the protrusion, the fine conduction line is electrically isolated from the silicon substrate.

A method of fabricating a quantum wire structure, comprising the steps of:

• providing a silicon substrate having (100) surface;
• forming an etching protection film and forming a pattern as a mask in the etching protection film;
• forming saw-tooth-like protrusions having (111) side planes by performing crystalline anisotropy etching with use of the mask of the etching protection film;
• removing the etching protection film;
• forming an oxidization protection film covering the top portion of the protrusion;
• and
• oxidizing the side planes of the saw-tooth-like protrusions so as to form an unoxidized area in the top portion of each protrusion under the oxidization protection film;
• whereby a fine conduction line is formed in the unoxidized region of each protrusion, each fine conduction line is electrically isolated from the silicon substrate.

A method of fabricating a quantum wire structure, comprising the steps of:

• providing a silicon substrate having (100) surface;
• forming an etching protection film and forming a pattern as a mask in the etching protection film;
• forming saw-tooth-like protrusions having (111) side planes by performing crystalline anisotropy etching with use of the mask of the etching protection film;
• removing the etching protection film;
• forming an ion implantation protection film covering the top portion of the protrusions;
• implanting oxygen ions into the portions of the side planes of the silicon substrate not protected by the ion implantation protection film;
• and
• forming an oxidation film in the ion implanted side planes by heat treatment;
• whereby the top portion of each protrusion under the ion implantation film remains unoxidized, and forms a fine conduction line which is electrically isolated from the silicon substrate.

A method of fabricating a quantum wire structure, comprising the steps of:

• providing a silicon substrate having (100) surface;
• forming an etching protection film and forming a pattern as a mask in the etching protection film;
• forming saw-tooth-like protrusions having (111) side planes by performing crystalline anisotropy etching with use of the mask of the etching protection film;
• removing the etching protection film;
• forming an ion implantation protection film covering the top of the protrusions;
• and
• implanting impurity ions into the portions of the silicon substrate not protected by the ion implantation protection film;
• whereby the top portion of each protrusion under the ion implantation film remains pure silicon, and forms a fine conduction line which is electrically isolated from the silicon substrate.

A method of fabrication a quantum wire structure, comprising the steps of:

• providing a silicon substrate having (100) surface;
• forming an etching protection film and forming a pattern as a mask in the etching protection film;
• implanting impurity ions through the etching protection film into the silicon substrate to form a shallow impurity layer having a polarity opposite that of the silicon substrate;
• forming saw-tooth-like protrusions having (111) side planes by performing crystalline anisotropy etching with use of the mask of the etching protection film, wherein the top portions of the saw-tooth-like protrusions are formed by the impurity layer;
• and
• removing the etching protection film;
• whereby the top portion of each saw-tooth-like protrusion formed by the impurity layer forms a fine conduction line which is electrically isolated from the silicon substrate.

A method of fabricating a quantum wire structure, comprising the steps of:

• providing a silicon substrate having (100) surface;
• forming an etching protection film and forming a pattern as a mask in the etching protection film;
• forming saw-tooth-like protrusions having (111) side planes by performing crystalline anisotropy etching with use of the mask of the etching protection film;
• removing the etching protection film;
• forming an insulator film on the surface of the substrate;
• embedding a silica glass on the surface of the insulator film except on the top portion of the saw-tooth-like protrusions;
• and
• forming a gate electrode film on the top portion of the saw-tooth-like protrusions;
• whereby a fine conduction line is formed in the top portion of each protrusions when a voltage is applied to the gate electrode film.

A method of fabricating a quantum wire structure, comprising the steps of:

• providing a silicon substrate having (100) surface;
• forming an etching protection film and forming a pattern as a mask in the etching protection film;
• forming saw-tooth-like protrusions having (111) side planes by performing crystalline anisotropy etching with use of the mask of the etching protection film;
• removing the etching protection film;
• layering an insulator film, a conductive polycrystalline silicon film and a metallic film successively on the surface of the semiconductor substrate;
• embedding a resist on the surface of the metallic layer except on the top portion of the saw-tooth-like protrusions;
• removing the metallic film covering the top portion of the saw-tooth-like protrusions and removing the resist;
• forming a metal silicide film by heat treatment to react the metallic film with the polycrystalline silicon;
• and
• removing the metallic silicide film selectively so that the conductive polycrystalline silicon film forms a gate electrode located on the top portion of the saw-tooth-like protrusions;
• whereby a fine conduction line is formed in the top portion of each protrusion when a voltage is applied to the gate electrode film.